Awakening guardian angels: drugging the p53 pathway

Key Points

  • p53 functions as the 'guardian of the genome' by inducing cell cycle arrest, senescence and apoptosis in response to oncogene activation, DNA damage and other stress signals. Loss of p53 function occurs in most human tumours by either mutation of TP53 itself or by inactivation of the p53 signal transduction pathway.

  • In many tumours p53 is inactivated by the overexpression of the negative regulators MDM2 and MDM4 or by the loss of activity of the MDM2 inhibitor ARF. The pathway can be reactivated in these tumours by small molecules that inhibit the interaction of MDM2 and/or MDM4 with p53. Such molecules are now in clinical trials.

  • Cell-based screens have been used to find several new non-genotoxic activators of the p53 response, which include inhibitors of protein deacetylating enzymes.

  • Molecules that bind and stabilize mutant p53 — restoring wild-type function — have been discovered by both structure-based design and cell-based screens.

  • Activating a p53-dependent cell cycle arrest in normal cells and tissues can protect them from the toxic effect of anti-mitotic drugs while not reducing their efficacy in killing p53 mutant tumour cells. This drug combination approach represents a new way to exploit the p53 system.

  • The intense study of the p53 pathway is helping to develop new paradigms in drug discovery and development that will have widespread application in other areas of drug discovery.


Currently, around 11 million people are living with a tumour that contains an inactivating mutation of TP53 (the human gene that encodes p53) and another 11 million have tumours in which the p53 pathway is partially abrogated through the inactivation of other signalling or effector components. The p53 pathway is therefore a prime target for new cancer drug development, and several original approaches to drug discovery that could have wide applications to drug development are being used. In one approach, molecules that activate p53 by blocking protein–protein interactions with MDM2 are in early clinical development. Remarkable progress has also been made in the development of p53-binding molecules that can rescue the function of certain p53 mutants. Finally, cell-based assays are being used to discover compounds that exploit the p53 pathway by either seeking targets and compounds that show synthetic lethality with TP53 mutations or by looking for non-genotoxic activators of the p53 response.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: The p53 pathway.
Figure 2: A negative feedback loop controls cellular levels of p53.
Figure 3: Structural applications to p53-based drug therapies.


  1. 1

    Paez, J. G. et al. EGFR mutations in lung cancer: correlation with clinical response to gefitinib therapy. Science 304, 1497–1500 (2004).

    CAS  Google Scholar 

  2. 2

    Pao, W. et al. EGF receptor gene mutations are common in lung cancers from “never smokers” and are associated with sensitivity of tumors to gefitinib and erlotinib. Proc. Natl Acad. Sci. USA 101, 13306–13311 (2004).

    CAS  Google Scholar 

  3. 3

    Lynch, T. J. et al. Activating mutations in the epidermal growth factor receptor underlying responsiveness of non-small-cell lung cancer to gefitinib. N. Engl. J. Med 350, 2129–2139 (2004).

    CAS  PubMed  Google Scholar 

  4. 4

    Capdeville, R., Buchdunger, E., Zimmermann, J. & Matter, A. Glivec (STI571, imatinib), a rationally developed, targeted anticancer drug. Nature Rev. Drug Discov. 1, 493–502 (2002).

    CAS  Google Scholar 

  5. 5

    Baselga, J. & Swain, S. M. Novel anticancer targets: revisiting ERBB2 and discovering ERBB3. Nature Rev. Cancer 9, 463–475 (2009).

    CAS  Google Scholar 

  6. 6

    Clackson, T. & Wells, J. A. A hot spot of binding energy in a hormone-receptor interface. Science 267, 383–386 (1995).

    CAS  PubMed  Google Scholar 

  7. 7

    Oltersdorf, T. et al. An inhibitor of Bcl-2 family proteins induces regression of solid tumours. Nature 435, 677–681 (2005).

    CAS  Article  Google Scholar 

  8. 8

    Vassilev, L. T. et al. In vivo activation of the p53 pathway by small-molecule antagonists of MDM2. Science 303, 844–848 (2004). This paper describes the successful isolation and characterization of the nutlin compounds that activate p53 by binding to MDM2 and blocking its interaction with p53. The authors show that the molecules are highly specific and active in xenograft models.

    CAS  Google Scholar 

  9. 9

    Dantzer, F. et al. Base excision repair is impaired in mammalian cells lacking Poly(ADP-ribose) polymerase-1. Biochemistry 39, 7559–7569 (2000).

    CAS  PubMed  Google Scholar 

  10. 10

    Ame, J. C., Spenlehauer, C. & de Murcia, G. The PARP superfamily. Bioessays 26, 882–893 (2004).

    CAS  PubMed  Google Scholar 

  11. 11

    Edwards, S. L. et al. Resistance to therapy caused by intragenic deletion in BRCA2. Nature 451, 1111–1115 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  12. 12

    Yu, J. & Zhang, L. No PUMA, no death: implications for p53-dependent apoptosis. Cancer Cell 4, 248–249 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  13. 13

    Moll, U. M., Wolff, S., Speidel, D. & Deppert, W. Transcription-independent pro-apoptotic functions of p53. Curr. Opin. Cell Biol. 17, 631–636 (2005).

    CAS  Google Scholar 

  14. 14

    Suzuki, H. I. et al. Modulation of microRNA processing by p53. Nature 460, 529–533 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  15. 15

    Ahn, J. et al. Dissection of the sequence-specific DNA binding and exonuclease activities reveals a superactive yet apoptotically impaired mutant p53 protein. Cell Cycle 8, 1603–1615 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  16. 16

    Mummenbrauer, T. et al. p53 protein exhibits 3'-to-5' exonuclease activity. Cell 85, 1089–1099 (1996).

    CAS  Google Scholar 

  17. 17

    Sengupta, S. & Harris, C. C. p53: traffic cop at the crossroads of DNA repair and recombination. Nature Rev. Mol. Cell Biol. 6, 44–55 (2005).

    CAS  Google Scholar 

  18. 18

    de Souza-Pinto, N. C., Harris, C. C. & Bohr, V. A. p53 functions in the incorporation step in DNA base excision repair in mouse liver mitochondria. Oncogene 23, 6559–6568 (2004).

    CAS  Google Scholar 

  19. 19

    Sommers, J. A. et al. p53 modulates RPA-dependent and RPA-independent WRN helicase activity. Cancer Res. 65, 1223–1233 (2005).

    CAS  PubMed  Google Scholar 

  20. 20

    Budanov, A. V. & Karin, M. p53 target genes sestrin1 and sestrin2 connect genotoxic stress and mTOR signaling. Cell 134, 451–460 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  21. 21

    Feng, Z. et al. The regulation of AMPK β1, TSC2, and PTEN expression by p53: stress, cell and tissue specificity, and the role of these gene products in modulating the IGF-1-AKT-mTOR pathways. Cancer Res. 67, 3043–3053 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  22. 22

    Martins, C. P., Brown-Swigart, L. & Evan, G. I. Modeling the therapeutic efficacy of p53 restoration in tumors. Cell 127, 1323–1334 (2006). This paper shows that restoration of p53 function in tumours using an inducible system is highly effective in inhibiting the growth of even advanced tumours.

    CAS  Google Scholar 

  23. 23

    Ventura, A. et al. Restoration of p53 function leads to tumour regression in vivo. Nature 445, 661–665 (2007). This paper demonstrates that p53 restoration induced by a genetic switch in a model system leads to tumour regression by apoptosis.

    CAS  Google Scholar 

  24. 24

    Xue, W. et al. Senescence and tumour clearance is triggered by p53 restoration in murine liver carcinomas. Nature 445, 656–660 (2007). This paper shows that in a mouse liver carcinoma model restoration of p53 activity in tumour cells induces senescence rather than cell death. Strikingly, the senescent cells are cleared by an innate immune response.

    CAS  PubMed  PubMed Central  Google Scholar 

  25. 25

    Bond, G. L., Hu, W. & Levine, A. A single nucleotide polymorphism in the MDM2 gene: from a molecular and cellular explanation to clinical effect. Cancer Res. 65, 5481–5484 (2005). In this paper a single nucleotide polymorphism that regulates the expression of MDM2 is shown to affect the probability of developing cancer.

    CAS  PubMed  Google Scholar 

  26. 26

    Vousden, K. H. & Lane, D. P. p53 in health and disease. Nature Rev. Mol. Cell Biol. 8, 275–283 (2007).

    CAS  Google Scholar 

  27. 27

    Picksley, S. M. & Lane, D. P. The p53-mdm2 autoregulatory feedback loop: a paradigm for the regulation of growth control by p53? Bioessays 15, 689–690 (1993).

    CAS  PubMed  Google Scholar 

  28. 28

    Momand, J., Zambetti, G. P., Olson, D. C., George, D. & Levine, A. J. The mdm-2 oncogene product forms a complex with the p53 protein and inhibits p53-mediated transactivation. Cell 69, 1237–1245 (1992). The original discovery of the p53–MDM2 interaction is described in this paper.

    CAS  PubMed  Google Scholar 

  29. 29

    Danovi, D. et al. Amplification of Mdmx (or Mdm4) directly contributes to tumor formation by inhibiting p53 tumor suppressor activity. Mol. Cell Biol. 24, 5835–5843 (2004).

    CAS  PubMed  PubMed Central  Google Scholar 

  30. 30

    Laurie, N. A. et al. Inactivation of the p53 pathway in retinoblastoma. Nature 444, 61–66 (2006).

    CAS  Article  Google Scholar 

  31. 31

    Riemenschneider, M. J. et al. Amplification and overexpression of the MDM4 (MDMX) gene from 1q32 in a subset of malignant gliomas without TP53 mutation or MDM2 amplification. Cancer Res. 59, 6091–6096 (1999).

    CAS  PubMed  PubMed Central  Google Scholar 

  32. 32

    Esteller, M. et al. p14ARF silencing by promoter hypermethylation mediates abnormal intracellular localization of MDM2. Cancer Res. 61, 2816–2821 (2001).

    CAS  PubMed  Google Scholar 

  33. 33

    Sherr, C. J. & Weber, J. D. The ARF/p53 pathway. Curr. Opin. Genet. Dev. 10, 94–99 (2000).

    CAS  PubMed  Google Scholar 

  34. 34

    Hainaut, P. & Hollstein, M. p53 and human cancer: the first ten thousand mutations. Adv. Cancer Res. 77, 81–137 (2000).

    CAS  PubMed  Google Scholar 

  35. 35

    Bullock, A. N., Henckel, J. & Fersht, A. R. Quantitative analysis of residual folding and DNA binding in mutant p53 core domain: definition of mutant states for rescue in cancer therapy. Oncogene 19, 1245–1256 (2000).

    CAS  PubMed  Google Scholar 

  36. 36

    Milner, J. & Medcalf, E. A. Cotranslation of activated mutant p53 with wild type drives the wild-type p53 protein into the mutant conformation. Cell 65, 765–774 (1991).

    CAS  PubMed  Google Scholar 

  37. 37

    Milner, J., Medcalf, E. A. & Cook, A. C. Tumor suppressor p53: analysis of wild-type and mutant p53 complexes. Mol. Cell Biol. 11, 12–19 (1991).

    CAS  PubMed  PubMed Central  Google Scholar 

  38. 38

    Sigal, A. & Rotter, V. Oncogenic mutations of the p53 tumor suppressor: the demons of the guardian of the genome. Cancer Res. 60, 6788–6793 (2000).

    CAS  Google Scholar 

  39. 39

    Levine, A. J. et al. The spectrum of mutations at the p53 locus. Evidence for tissue-specific mutagenesis, selection of mutant alleles, and a “gain of function” phenotype. Ann. NY Acad. Sci. 768, 111–128 (1995).

    CAS  PubMed  Google Scholar 

  40. 40

    Irwin, M. S. Family feud in chemosensitvity: p73 and mutant p53. Cell Cycle 3, 319–323 (2004).

    CAS  Google Scholar 

  41. 41

    Li, Y. & Prives, C. Are interactions with p63 and p73 involved in mutant p53 gain of oncogenic function? Oncogene 26, 2220–2225 (2007).

    CAS  PubMed  Google Scholar 

  42. 42

    Strano, S. et al. Mutant p53: an oncogenic transcription factor. Oncogene 26, 2212–2219 (2007).

    CAS  PubMed  Google Scholar 

  43. 43

    Kim, E. & Deppert, W. Transcriptional activities of mutant p53: when mutations are more than a loss. J. Cell Biochem. 93, 878–886 (2004).

    CAS  Google Scholar 

  44. 44

    Levine, A. J. & Oren, M. The first 30 years of p53: growing ever more complex. Nature Rev. Cancer 9, 749–758 (2009).

    CAS  Google Scholar 

  45. 45

    Selivanova, G. et al. Restoration of the growth suppression function of mutant p53 by a synthetic peptide derived from the p53 C-terminal domain. Nature Med. 3, 632–638 (1997).

    CAS  PubMed  Google Scholar 

  46. 46

    Foster, B. A., Coffey, H. A., Morin, M. J. & Rastinejad, F. Pharmacological rescue of mutant p53 conformation and function. Science 286, 2507–2510 (1999).

    CAS  PubMed  PubMed Central  Google Scholar 

  47. 47

    Joerger, A. C., Ang, H. C. & Fersht, A. R. Structural basis for understanding oncogenic p53 mutations and designing rescue drugs. Proc. Natl Acad. Sci. USA 103, 15056–15061 (2006). This paper describes the first key step in the rational design of specific drugs that can re-activate p53 by binding to it and protecting it from unfolding.

    CAS  PubMed  Google Scholar 

  48. 48

    Shangary, S. et al. Temporal activation of p53 by a specific MDM2 inhibitor is selectively toxic to tumors and leads to complete tumor growth inhibition. Proc. Natl Acad. Sci. USA 105, 3933–3938 (2008).

    CAS  Google Scholar 

  49. 49

    Bykov, V. J. et al. Restoration of the tumor suppressor function to mutant p53 by a low-molecular-weight compound. Nature Med. 8, 282–288 (2002). In this paper the authors use a cell-based screen to search for molecules that only kill cells expressing mutant p53. They identify PRIMA-1 as a compound that has this activity and can restore wild-type p53 function to mutant p53. A modified version of Prima-1 (APR-246) is now in clinical trials.

    CAS  PubMed  PubMed Central  Google Scholar 

  50. 50

    Lain, S. et al. Discovery, in vivo activity, and mechanism of action of a small-molecule p53 activator. Cancer Cell 13, 454–463 (2008). This paper describes a cell-based screen that leads to the identification of new p53-activating molecules. The target of these new molecules is then defined using a genetic screen in yeast that shows that they function by blocking the deacetylation of p53 by the sirtuins.

    CAS  PubMed  PubMed Central  Google Scholar 

  51. 51

    Issaeva, N. et al. Small molecule RITA binds to p53, blocks p53-HDM-2 interaction and activates p53 function in tumors. Nature Med. 10, 1321–1328 (2004).

    CAS  Google Scholar 

  52. 52

    Sur, S. et al. A panel of isogenic human cancer cells suggests a therapeutic approach for cancers with inactivated p53. Proc. Natl Acad. Sci. USA 106, 3964–3969 (2009). An exciting study that shows that prior activation of the p53 pathway with the MDM2 inhibitor nutlin protects against the neutrophil depletion that is induced by mitotic inhibitors that block the activity of PLK1. Using this drug combination can alleviate the side effects of chemotherapy without reducing its ability to kill p53 mutant tumour cells.

    CAS  Google Scholar 

  53. 53

    Cheok, C. F., Dey, A. & Lane, D. P. Cyclin-dependent kinase inhibitors sensitize tumor cells to nutlin-induced apoptosis: a potent drug combination. Mol. Cancer Res. 5, 1133–1145 (2007).

    CAS  Google Scholar 

  54. 54

    Fang, B. & Roth, J. A. Tumor-suppressing gene therapy. Cancer Biol. Ther. 2, S115–121 (2003).

    CAS  PubMed  Google Scholar 

  55. 55

    Nishizaki, M. et al. Recombinant adenovirus expressing wild-type p53 is antiangiogenic: a proposed mechanism for bystander effect. Clin. Cancer Res. 5, 1015–1023 (1999).

    CAS  PubMed  Google Scholar 

  56. 56

    McCormick, F. Cancer-specific viruses and the development of ONYX-015. Cancer Biol. Ther. 2, S157–160 (2003).

    CAS  PubMed  Google Scholar 

  57. 57

    Joerger, A. C. & Fersht, A. R. Structural biology of the tumor suppressor p53. Annu. Rev. Biochem. 77, 557–582 (2008).

    CAS  PubMed  Google Scholar 

  58. 58

    Terzian, T. et al. The inherent instability of mutant p53 is alleviated by Mdm2 or p16INK4a loss. Genes Dev. 22, 1337–1344 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  59. 59

    Hupp, T. R., Meek, D. W., Midgley, C. A. & Lane, D. P. Regulation of the specific DNA binding function of p53. Cell 71, 875–886 (1992).

    CAS  PubMed  Google Scholar 

  60. 60

    Hupp, T. R., Sparks, A. & Lane, D. P. Small peptides activate the latent sequence-specific DNA binding function of p53. Cell 83, 237–245 (1995).

    CAS  PubMed  Google Scholar 

  61. 61

    Selivanova, G., Ryabchenko, L., Jansson, E., Iotsova, V. & Wiman, K. G. Reactivation of mutant p53 through interaction of a C-terminal peptide with the core domain. Mol. Cell Biol. 19, 3395–3402 (1999).

    CAS  PubMed  PubMed Central  Google Scholar 

  62. 62

    Kim, A. L. et al. Conformational and molecular basis for induction of apoptosis by a p53 C-terminal peptide in human cancer cells. J. Biol. Chem. 274, 34924–34931 (1999).

    CAS  PubMed  Google Scholar 

  63. 63

    Snyder, E. L., Meade, B. R., Saenz, C. C. & Dowdy, S. F. Treatment of terminal peritoneal carcinomatosis by a transducible p53-activating peptide. PLoS Biol. 2, E36 (2004).

    PubMed  PubMed Central  Google Scholar 

  64. 64

    Lane, D. Curing cancer with p53. N. Engl. J. Med. 350, 2711–2712 (2004).

    CAS  PubMed  Google Scholar 

  65. 65

    Rippin, T. M. et al. Characterization of the p53-rescue drug CP-31398 in vitro and in living cells. Oncogene 21, 2119–2129 (2002).

    CAS  PubMed  Google Scholar 

  66. 66

    Stephen, C. W. & Lane, D. P. Mutant conformation of p53. Precise epitope mapping using a filamentous phage epitope library. J. Mol. Biol. 225, 577–583 (1992).

    CAS  PubMed  Google Scholar 

  67. 67

    Milner, J., Cook, A. & Sheldon, M. A new anti-p53 monoclonal antibody, previously reported to be directed against the large T antigen of simian virus 40. Oncogene 1, 453–455 (1987).

    CAS  PubMed  Google Scholar 

  68. 68

    Milner, J. Flexibility: the key to p53 function? Trends Biochem. Sci. 20, 49–51 (1995).

    CAS  PubMed  Google Scholar 

  69. 69

    Boeckler, F. M. et al. Targeted rescue of a destabilized mutant of p53 by an in silico screened drug. Proc. Natl Acad. Sci. USA 105, 10360–10365 (2008).

    CAS  PubMed  Google Scholar 

  70. 70

    Haggarty, S. J. et al. Dissecting cellular processes using small molecules: identification of colchicine-like, taxol-like and other small molecules that perturb mitosis. Chem. Biol. 7, 275–286 (2000).

    CAS  PubMed  Google Scholar 

  71. 71

    Lambert, J. M. et al. PRIMA-1 reactivates mutant p53 by covalent binding to the core domain. Cancer Cell 15, 376–388 (2009).

    CAS  PubMed  Google Scholar 

  72. 72

    Kudo, N. et al. Leptomycin B inactivates CRM1/exportin 1 by covalent modification at a cysteine residue in the central conserved region. Proc. Natl Acad. Sci. USA 96, 9112–9117 (1999).

    CAS  PubMed  Google Scholar 

  73. 73

    Farmer, H. et al. Targeting the DNA repair defect in BRCA mutant cells as a therapeutic strategy. Nature 434, 917–921 (2005).

    CAS  Google Scholar 

  74. 74

    Oliner, J. D., Kinzler, K. W., Meltzer, P. S., George, D. L. & Vogelstein, B. Amplification of a gene encoding a p53-associated protein in human sarcomas. Nature 358, 80–83 (1992).

    CAS  PubMed  Google Scholar 

  75. 75

    Momand, J., Jung, D., Wilczynski, S. & Niland, J. The MDM2 gene amplification database. Nucleic Acids Res. 26, 3453–3459 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  76. 76

    Mendrysa, S. M. et al. Tumor suppression and normal aging in mice with constitutively high p53 activity. Genes Dev. 20, 16–21 (2006). An elegant paper that uses hypomorphic alleles of Mdm2 to show that slightly increased levels of p53 activity can allow normal growth while blocking tumour development.

    CAS  PubMed  PubMed Central  Google Scholar 

  77. 77

    Tovar, C. et al. Small-molecule MDM2 antagonists reveal aberrant p53 signaling in cancer: implications for therapy. Proc. Natl Acad. Sci. USA 103, 1888–1893 (2006).

    CAS  Google Scholar 

  78. 78

    Grasberger, B. L. et al. Discovery and cocrystal structure of benzodiazepinedione HDM2 antagonists that activate p53 in cells. J. Med. Chem. 48, 909–912 (2005).

    CAS  PubMed  Google Scholar 

  79. 79

    Ding, K. et al. Structure-based design of potent non-peptide MDM2 inhibitors. J. Am. Chem. Soc. 127, 10130–10131 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  80. 80

    Ding, K. et al. Structure-based design of spiro-oxindoles as potent, specific small-molecule inhibitors of the MDM2-p53 interaction. J. Med. Chem. 49, 3432–3435 (2006).

    CAS  Google Scholar 

  81. 81

    Koblish, H. K. et al. Benzodiazepinedione inhibitors of the Hdm2:p53 complex suppress human tumor cell proliferation in vitro and sensitize tumors to doxorubicin in vivo. Mol. Cancer Ther. 5, 160–169 (2006).

    CAS  PubMed  Google Scholar 

  82. 82

    Leonard, K. et al. Novel 1,4-benzodiazepine-2,5-diones as Hdm2 antagonists with improved cellular activity. Bioorg. Med. Chem. Lett. 16, 3463–3468 (2006).

    CAS  PubMed  Google Scholar 

  83. 83

    Parks, D. J. et al. Enhanced pharmacokinetic properties of 1,4-benzodiazepine-2,5-dione antagonists of the HDM2-p53 protein-protein interaction through structure-based drug design. Bioorg. Med. Chem. Lett. 16, 3310–3314 (2006).

    CAS  PubMed  Google Scholar 

  84. 84

    Shangary, S. & Wang, S. Small-molecule inhibitors of the MDM2-p53 protein-protein interaction to reactivate p53 function: a novel approach for cancer therapy. Annu. Rev. Pharmacol. Toxicol. 49, 223–241 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  85. 85

    Parant, J. et al. Rescue of embryonic lethality in Mdm4-null mice by loss of Trp53 suggests a nonoverlapping pathway with MDM2 to regulate p53. Nature Genet. 29, 92–95 (2001).

    CAS  PubMed  Google Scholar 

  86. 86

    Montes de Oca Luna, R., Wagner, D. S. & Lozano, G. Rescue of early embryonic lethality in mdm2-deficient mice by deletion of p53. Nature 378, 203–206 (1995). This paper and reference 75 establish that p53 can induce embryonic lethality if it is not regulated by MDM2.

    CAS  PubMed  PubMed Central  Google Scholar 

  87. 87

    Jones, S. N., Roe, A. E., Donehower, L. A. & Bradley, A. Rescue of embryonic lethality in Mdm2-deficient mice by absence of p53. Nature 378, 206–208 (1995).

    CAS  Google Scholar 

  88. 88

    Stad, R. et al. Mdmx stabilizes p53 and Mdm2 via two distinct mechanisms. EMBO Rep. 2, 1029–1034 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  89. 89

    Linke, K. et al. Structure of the MDM2/MDMX RING domain heterodimer reveals dimerization is required for their ubiquitylation in trans. Cell Death Differ. 15, 841–848 (2008).

    CAS  Google Scholar 

  90. 90

    Tanimura, S. et al. MDM2 interacts with MDMX through their RING finger domains. FEBS Lett. 9447, 5–9 (1999).

    Google Scholar 

  91. 91

    Sharp, D. A., Kratowicz, S. A., Sank, M. J. & George, D. L. Stabilization of the MDM2 oncoprotein by interaction with the structurally related MDMX protein. J. Biol. Chem. 274, 38189–38196 (1999).

    CAS  PubMed  Google Scholar 

  92. 92

    Linares, L. K., Hengstermann, A., Ciechanover, A., Muller, S. & Scheffner, M. HdmX stimulates Hdm2-mediated ubiquitination and degradation of p53. Proc. Natl Acad. Sci. USA 100, 12009–12014 (2003).

    CAS  PubMed  Google Scholar 

  93. 93

    Gu, J. et al. Mutual dependence of MDM2 and MDMX in their functional inactivation of p53. J. Biol. Chem. 277, 19251–19254 (2002).

    CAS  Google Scholar 

  94. 94

    Pan, Y. & Chen, J. MDM2 promotes ubiquitination and degradation of MDMX. Mol. Cell Biol. 23, 5113–5121 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  95. 95

    Kawai, H. et al. DNA damage-induced MDMX degradation is mediated by MDM2. J. Biol. Chem. 278, 45946–45953 (2003).

    CAS  PubMed  Google Scholar 

  96. 96

    de Graaf, P. et al. Hdmx protein stability is regulated by the ubiquitin ligase activity of Mdm2. J. Biol. Chem. 278, 38315–38324 (2003).

    CAS  PubMed  Google Scholar 

  97. 97

    Wade, M. & Wahl, G. M. Targeting Mdm2 and Mdmx in cancer therapy: better living through medicinal chemistry? Mol. Cancer Res. 7, 1–11 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  98. 98

    Ramos, Y. F. et al. Aberrant expression of HDMX proteins in tumor cells correlates with wild-type p53. Cancer Res. 61, 1839–1842 (2001).

    CAS  PubMed  Google Scholar 

  99. 99

    Bartel, F. et al. Significance of HDMX-S (or MDM4) mRNA splice variant overexpression and HDMX gene amplification on primary soft tissue sarcoma prognosis. Int. J. Cancer 117, 469–475 (2005).

    CAS  PubMed  Google Scholar 

  100. 100

    Bottger, V. et al. Comparative study of the p53-mdm2 and p53-MDMX interfaces. Oncogene 18, 189–199 (1999).

    CAS  PubMed  Google Scholar 

  101. 101

    Pazgier, M. et al. Structural basis for high-affinity peptide inhibition of p53 interactions with MDM2 and MDMX. Proc. Natl Acad. Sci. USA 106, 4665–4670 (2009).

    CAS  PubMed  Google Scholar 

  102. 102

    Bernal, F., Tyler, A. F., Korsmeyer, S. J., Walensky, L. D. & Verdine, G. L. Reactivation of the p53 tumor suppressor pathway by a stapled p53 peptide. J. Am. Chem. Soc. 129, 2456–2457 (2007).

    CAS  PubMed  PubMed Central  Google Scholar 

  103. 103

    Czarna, A. et al. High affinity interaction of the p53 peptide-analogue with human Mdm2 and Mdmx. Cell Cycle 8, 1176–1184 (2009).

    CAS  PubMed  Google Scholar 

  104. 104

    Karlsson, G. B. et al. Activation of p53 by scaffold-stabilised expression of Mdm2-binding peptides: visualisation of reporter gene induction at the single-cell level. Br. J. Cancer 91, 1488–1494 (2004).

    CAS  PubMed  PubMed Central  Google Scholar 

  105. 105

    Yang, Y. et al. Small molecule inhibitors of HDM2 ubiquitin ligase activity stabilize and activate p53 in cells. Cancer Cell 7, 547–559 (2005).

    CAS  PubMed  Google Scholar 

  106. 106

    Brummelkamp, T. R. et al. An shRNA barcode screen provides insight into cancer cell vulnerability to MDM2 inhibitors. Nature Chem. Biol. 2, 202–206 (2006).

    CAS  Google Scholar 

  107. 107

    Dayal, S. et al. Suppression of the deubiquitinating enzyme USP5 causes the accumulation of unanchored polyubiquitin and the activation of p53. J. Biol. Chem. 284, 5030–5041 (2009).

    CAS  PubMed  Google Scholar 

  108. 108

    Lane, D. P. Cancer. p53, guardian of the genome. Nature 358, 15–16 (1992). The news and views commentary that named p53 as “guardian of the genome”, emphasizing its role in the DNA damage response.

    CAS  PubMed  Google Scholar 

  109. 109

    Sohn, T. A., Bansal, R., Su, G. H., Murphy, K. M. & Kern, S. E. High-throughput measurement of the Tp53 response to anticancer drugs and random compounds using a stably integrated Tp53-responsive luciferase reporter. Carcinogenesis 23, 949–957 (2002).

    CAS  PubMed  Google Scholar 

  110. 110

    Berkson, R. G. et al. Pilot screening programme for small molecule activators of p53. Int. J. Cancer 115, 701–710 (2005).

    CAS  PubMed  Google Scholar 

  111. 111

    Gurova, K. V. et al. Small molecules that reactivate p53 in renal cell carcinoma reveal a NF-kappaB-dependent mechanism of p53 suppression in tumors. Proc. Natl Acad. Sci. USA 102, 17448–17453 (2005).

    CAS  PubMed  Google Scholar 

  112. 112

    Maclean, K. H., Dorsey, F. C., Cleveland, J. L. & Kastan, M. B. Targeting lysosomal degradation induces p53-dependent cell death and prevents cancer in mouse models of lymphomagenesis. J. Clin. Invest. 118, 79–88 (2008).

    CAS  PubMed  Google Scholar 

  113. 113

    Gottifredi, V., Shieh, S., Taya, Y. & Prives, C. p53 accumulates but is functionally impaired when DNA synthesis is blocked. Proc. Natl Acad. Sci. USA 98, 1036–1041 (2001).

    CAS  PubMed  Google Scholar 

  114. 114

    Sun, X. X., Dai, M. S. & Lu, H. Mycophenolic acid activation of p53 requires ribosomal proteins L5 and L11. J. Biol. Chem. 283, 12387–12392 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  115. 115

    Linke, S. P., Clarkin, K. C., Di Leonardo, A., Tsou, A. & Wahl, G. M. A reversible, p53-dependent G0/G1 cell cycle arrest induced by ribonucleotide depletion in the absence of detectable DNA damage. Genes Dev. 10, 934–947 (1996).

    CAS  PubMed  Google Scholar 

  116. 116

    te Poele, R. H., Okorokov, A. L. & Joel, S. P. RNA synthesis block by 5,6-dichloro-1-β-D-ribofuranosylbenzimidazole (DRB) triggers p53-dependent apoptosis in human colon carcinoma cells. Oncogene 18, 5765–5772 (1999).

    CAS  PubMed  Google Scholar 

  117. 117

    Ljungman, M., Zhang, F., Chen, F., Rainbow, A. J. & McKay, B. C. Inhibition of RNA polymerase II as a trigger for the p53 response. Oncogene 18, 583–592 (1999).

    CAS  PubMed  Google Scholar 

  118. 118

    Choong, M. L., Yang, H., Lee, M. A. & Lane, D. P. Specific activation of the p53 pathway by low dose actinomycin D: A new route to p53 based cyclotherapy. Cell Cycle 8, 2810–2818 (2009).

    CAS  Google Scholar 

  119. 119

    Lohrum, M. A., Ludwig, R. L., Kubbutat, M. H., Hanlon, M. & Vousden, K. H. Regulation of HDM2 activity by the ribosomal protein L11. Cancer Cell 3, 577–587 (2003).

    CAS  Google Scholar 

  120. 120

    Lindstrom, M. S., Jin, A., Deisenroth, C., White Wolf, G. & Zhang, Y. Cancer-associated mutations in the MDM2 zinc finger domain disrupt ribosomal protein interaction and attenuate MDM2-induced p53 degradation. Mol. Cell Biol. 27, 1056–1068 (2007).

    CAS  PubMed  Google Scholar 

  121. 121

    Rubbi, C. P. & Milner, J. Disruption of the nucleolus mediates stabilization of p53 in response to DNA damage and other stresses. EMBO J. 22, 6068–6077 (2003).

    CAS  PubMed  PubMed Central  Google Scholar 

  122. 122

    Foster, S. A., Demers, G. W., Etscheid, B. G. & Galloway, D. A. The ability of human papillomavirus E6 proteins to target p53 for degradation in vivo correlates with their ability to abrogate actinomycin D-induced growth arrest. J. Virol. 68, 5698–5705 (1994).

    CAS  PubMed  PubMed Central  Google Scholar 

  123. 123

    Green, D. M. et al. Comparison between single-dose and divided-dose administration of dactinomycin and doxorubicin for patients with Wilms' tumor: a report from the National Wilms' Tumor Study Group. J. Clin. Oncol. 16, 237–245 (1998).

    CAS  PubMed  Google Scholar 

  124. 124

    Staples, O. D. et al. Characterization, chemical optimization and anti-tumour activity of a tubulin poison identified by a p53-based phenotypic screen. Cell Cycle 7, 3417–3427 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  125. 125

    Krajewski, M., Ozdowy, P., D'Silva, L., Rothweiler, U. & Holak, T. A. NMR indicates that the small molecule RITA does not block p53-MDM2 binding in vitro. Nature Med. 11, 1135–1136 (2005).

    CAS  PubMed  Google Scholar 

  126. 126

    Yang, J. et al. Small-molecule activation of p53 blocks hypoxia-inducible factor 1α and vascular endothelial growth factor expression in vivo and leads to tumor cell apoptosis in normoxia and hypoxia. Mol. Cell Biol. 29, 2243–2253 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  127. 127

    Rivera, M. I. et al. Selective toxicity of the tricyclic thiophene NSC 652287 in renal carcinoma cell lines: differential accumulation and metabolism. Biochem. Pharmacol. 57, 1283–1295 (1999).

    CAS  PubMed  Google Scholar 

  128. 128

    Nieves-Neira, W. et al. DNA protein cross-links produced by NSC 652287, a novel thiophene derivative active against human renal cancer cells. Mol. Pharmacol. 56, 478–484 (1999).

    CAS  PubMed  Google Scholar 

  129. 129

    Yang, J., Ahmed, A. & Ashcroft, M. Activation of a unique p53-dependent DNA damage response. Cell Cycle 8, 1630–1632 (2009).

    CAS  PubMed  Google Scholar 

  130. 130

    Enge, M. et al. MDM2-dependent downregulation of p21 and hnRNP K provides a switch between apoptosis and growth arrest induced by pharmacologically activated p53. Cancer Cell 15, 171–183 (2009).

    CAS  PubMed  Google Scholar 

  131. 131

    Grinkevich, V. V. et al. Ablation of key oncogenic pathways by RITA-reactivated p53 is required for efficient apoptosis. Cancer Cell 15, 441–453 (2009).

    CAS  Google Scholar 

  132. 132

    Luo, J. et al. Negative control of p53 by Sir2α promotes cell survival under stress. Cell 107, 137–148 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  133. 133

    Vaziri, H. et al. hSIR2SIRT1 functions as an NAD-dependent p53 deacetylase. Cell 107, 149–159 (2001).

    CAS  PubMed  PubMed Central  Google Scholar 

  134. 134

    Langley, E. et al. Human SIR2 deacetylates p53 and antagonizes PML/p53-induced cellular senescence. EMBO J. 21, 2383–2396 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  135. 135

    Mutka, S. C. et al. Identification of nuclear export inhibitors with potent anticancer activity in vivo. Cancer Res. 69, 510–517 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  136. 136

    Blagosklonny, M. V. Basic cell cycle and cancer research: is harmony impossible? Cell Cycle 1, 3–5 (2002).

    CAS  PubMed  Google Scholar 

  137. 137

    Carvajal, D. et al. Activation of p53 by MDM2 antagonists can protect proliferating cells from mitotic inhibitors. Cancer Res. 65, 1918–1924 (2005).

    CAS  PubMed  PubMed Central  Google Scholar 

  138. 138

    Soucek, L. et al. Modelling Myc inhibition as a cancer therapy. Nature 455, 679–683 (2008).

    CAS  PubMed  PubMed Central  Google Scholar 

  139. 139

    van Montfort, R. L. & Workman, P. Structure-based design of molecular cancer therapeutics. Trends Biotechnol. 27, 315–328 (2009).

    CAS  PubMed  Google Scholar 

  140. 140

    Nienaber, V. et al. Discovering novel ligands for macromolecules using X-ray crystallographic screening. Nature Biotechnol. 18, 1105–1108 (2000).

    CAS  Google Scholar 

  141. 141

    Wang, Y. V., Leblanc, M., Wade, M., Jochemsen, A. G., Wahl, G. M. Increased radioresistance and accelerated B Cell lymphomas in mice with Mdmx mutations that prevent modifications by DNA-damage-activated kinases. Cancer Cell 16, 33–43 (2009).

    PubMed  PubMed Central  Google Scholar 

  142. 142

    Vassilev, L. T. MDM2 inhibitors for cancer therapy. Trends Mol. Med. 13, 23–31 (2007).

    CAS  PubMed  Google Scholar 

  143. 143

    Zhang, Y. & Xiong, Y. Control of p53 ubiquitination and nuclear export by MDM2 and ARF. Cell Growth Differ. 12, 175–186 (2001).

    CAS  PubMed  Google Scholar 

  144. 144

    Robertson, K. D. & Jones, P. A. The human ARF cell cycle regulatory gene promoter is a CpG island which can be silenced by DNA methylation and down-regulated by wild-type p53. Mol. Cell Biol. 18, 6457–6473 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  145. 145

    Honda, R. & Yasuda, H. Activity of MDM2, a ubiquitin ligase, toward p53 or itself is dependent on the RING finger domain of the ligase. Oncogene 19, 1473–1476 (2000).

    CAS  PubMed  Google Scholar 

  146. 146

    Fang, S., Jensen, J. P., Ludwig, R. L., Vousden, K. H. & Weissman, A. M. Mdm2 is a RING finger-dependent ubiquitin protein ligase for itself and p53. J. Biol. Chem. 275, 8945–8951 (2000).

    CAS  PubMed  Google Scholar 

  147. 147

    Newlands, E. S., Rustin, G. J., Brampton, M. H. Phase I trial elactocin. Br. J. Cancer 74, 648–649 (1996).

    CAS  PubMed  PubMed Central  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to David P. Lane.

Related links

Related links


National Cancer Institute Drug Dictionary 

actinomycin D












Pathway Interaction Database 

p53 pathway


Laboratory homepage


Cytotoxic chemotherapy

Cell-killing drugs used to treat various cancers by targeting rapidly dividing cells.

Missense mutation

A single nucleotide is changed, resulting in a codon that encodes a different amino acid (non-synonymous).

Forward chemical genetics

FCG. Libraries of small molecules are screened for their ability to induce a particular phenotype in cells or cellular extracts. FCG requires three components: a collection of compounds, a biological assay with a quantifiable phenotypic output and a method to identify the target(s) of the active compounds.

Differential scanning calorimetry

Measures the heat changes that occur in biomolecules during controlled increases or decreases in temperature. It measures the enthalpy of unfolding and the change in heat capacity owing to heat denaturation: the higher the thermal transition (melting point) the more stable the molecule.

Michael acceptor

The Michael reaction occurs between a Michael donor (such as cysteine residues in proteins) and a Michael acceptor molecule (such as leptomycin B) in the presence of a base. The reaction itself is the nucleophillic addition of a carbanion to an α-, β-unsaturated carbonyl compound.

Synthetic lethality

Two genes are in a synthetic lethal relationship if a mutation in both genes leads to cell death but a mutation in one gene alone does not.


Molecules that interact with a specific target molecule usually generated from a large random artificial library, which can be RNA-, DNA-, peptide- or protein-based.

Cis-imidazoline compounds

A class of compounds synthesized around a core imidazole structure, such as the nutlins.


Chemical compounds with a core chemical structure that is the fusion of a benzene ring and a diazepine ring.


A molecule with a core scaffold that contains a tryptophan-like structure.


The concentration of a drug that causes a 50% inhibition of the activity of a target enzyme.

Topoisomerse inhibitors

Chemotherapy agents that interfere with the actions of topoisomerase 1 and topoisomerase 2, which are involved in DNA replication during the cell cycle.


A compound that stabilizes microtubules by irreversibly binding to the β-subunit of tubulin.

Vinca alkaloids

Anti-mitotic and anti-microtubule agents that prevent tubulin polymerization and so interfere with chromosomal replication and subsequent separation.


An olomoucine-related purine flavopiridol, which is a highly potent inhibitor of the kinase activity of cyclin-dependent kinases CDK1, CDK2, CDK5 and CDK7. It induces the activation, stabilization and accumulation of p53 in the nucleus through the suppression of MDM2 expression and partial inhibition of its transcription.


A haematological disorder characterized by an abnormally low number of neurophils.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Brown, C., Lain, S., Verma, C. et al. Awakening guardian angels: drugging the p53 pathway. Nat Rev Cancer 9, 862–873 (2009).

Download citation

Further reading


Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing