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Essential, non-redundant roles of B-Raf and Raf-1 in Ras-driven skin tumorigenesis

Abstract

Ras-driven tumorigenesis is assumed to depend on Raf for ERK activation and proliferation; yet, an in vivo requirement for Raf as MEK/ERK activator in this setting has not been demonstrated to date. Here, we show that epidermis-restricted B-Raf ablation restrains the onset and stops the progression of established Ras-driven tumors by limiting MEK/ERK activation and proliferation. Concomitant elimination of B-Raf and Raf-1 enforces the abrupt regression of established tumors owing to the decrease in ERK activation and proliferation caused by B-Raf ablation combined with the ERK-independent increase in Rho-dependent kinase (Rok) signaling and differentiation triggered by Raf-1 inactivation. Thus, B-Raf and Raf-1 have non-redundant functions in Ras-driven tumorigenesis. Of note, Raf kinase inhibitors achieve impressive results in melanomas harboring oncogenic BRAF, but are ineffective against Ras-driven tumors; moreover, therapy-related skin tumors driven by a paradox ERK activation as well as primary and acquired resistance have been reported. Our results suggest that therapies targeting both Raf kinase-dependent and -independent pathways may be effective against a broader range of malignancies and reduce the risks of adverse effects and/or resistance.

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References

  1. Kern F, Niault T, Baccarini M . Ras and Raf pathways in epidermis development and carcinogenesis. Br J Cancer 2011; 104: 229–234.

    CAS  Article  Google Scholar 

  2. Khavari TA, Rinn J . Ras/Erk MAPK signaling in epidermal homeostasis and neoplasia. Cell Cycle 2007; 6: 2928–2931.

    CAS  Article  Google Scholar 

  3. Oki-Idouchi CE, Lorenzo PS . Transgenic overexpression of RasGRP1 in mouse epidermis results in spontaneous tumors of the skin. Cancer Res 2007; 67: 276–280.

    CAS  Article  Google Scholar 

  4. Vitale-Cross L, Amornphimoltham P, Fisher G, Molinolo AA, Gutkind JS . Conditional expression of K-ras in an epithelial compartment that includes the stem cells is sufficient to promote squamous cell carcinogenesis. Cancer Res 2004; 64: 8804–8807.

    CAS  Article  Google Scholar 

  5. Sibilia M, Fleischmann A, Behrens A, Stingl L, Carroll J, Watt FM et al. The EGF receptor provides an essential survival signal for SOS- dependent skin tumor development. Cell 2000; 102: 211–220.

    CAS  Article  Google Scholar 

  6. Wang Z, Pedersen E, Basse A, Lefever T, Peyrollier K, Kapoor S et al. Rac1 is crucial for Ras-dependent skin tumor formation by controlling Pak1-Mek-Erk hyperactivation and hyperproliferation in vivo. Oncogene 2010.

  7. Murayama K, Kimura T, Tarutani M, Tomooka M, Hayashi R, Okabe M et al. Akt activation induces epidermal hyperplasia and proliferation of epidermal progenitors. Oncogene 2007; 26: 4882–4888.

    CAS  Article  Google Scholar 

  8. Malliri A, van der Kammen RA, Clark K, van der Valk M, Michiels F, Collard JG . Mice deficient in the Rac activator Tiam1 are resistant to Ras-induced skin tumours. Nature 2002; 417: 867–871.

    CAS  Article  Google Scholar 

  9. Gupta S, Ramjaun AR, Haiko P, Wang Y, Warne PH, Nicke B et al. Binding of ras to phosphoinositide 3-kinase p110alpha is required for ras-driven tumorigenesis in mice. Cell 2007; 129: 957–968.

    CAS  Article  Google Scholar 

  10. Gonzalez-Garcia A, Pritchard CA, Paterson HF, Mavria G, Stamp G, Marshall CJ . RalGDS is required for tumor formation in a model of skin carcinogenesis. Cancer Cell 2005; 7: 219–226.

    CAS  Article  Google Scholar 

  11. Galabova-Kovacs G, Matzen D, Piazzolla D, Meissl K, Plyushch T, Chen AP et al. Essential role of B-Raf in ERK activation during extraembryonic development. Proc Natl Acad Sci USA. 2006; 103: 1325–1330.

    CAS  Article  Google Scholar 

  12. Ehrenreiter K, Piazzolla D, Velamoor V, Sobczak I, Small JV, Takeda J et al. Raf-1 regulates Rho signaling and cell migration. J Cell Biol 2005; 168: 955–964.

    CAS  Article  Google Scholar 

  13. Scholl FA, Dumesic PA, Barragan DI, Harada K, Bissonauth V, Charron J et al. Mek1/2 MAPK kinases are essential for Mammalian development, homeostasis, and Raf-induced hyperplasia. Dev Cell 2007; 12: 615–629.

    CAS  Article  Google Scholar 

  14. Dumesic PA, Scholl FA, Barragan DI, Khavari PA, Erk1/2 MAP . kinases are required for epidermal G2/M progression. J Cell Biol 2009; 185: 409–422.

    CAS  Article  Google Scholar 

  15. Scholl FA, Dumesic PA, Barragan DI, Charron J, Khavari PA . Mek1/2 gene dosage determines tissue response to oncogenic Ras signaling in the skin. Oncogene 2009; 28: 1485–1495.

    CAS  Article  Google Scholar 

  16. Scholl FA, Dumesic PA, Barragan DI, Harada K, Charron J, Khavari PA . Selective role for Mek1 but not Mek2 in the induction of epidermal neoplasia. Cancer Res 2009; 69: 3772–3778.

    CAS  Article  Google Scholar 

  17. Bourcier C, Jacquel A, Hess J, Peyrottes I, Angel P, Hofman P et al. p44 mitogen-activated protein kinase (extracellular signal-regulated kinase 1)-dependent signaling contributes to epithelial skin carcinogenesis. Cancer Res 2006; 66: 2700–2707.

    CAS  Article  Google Scholar 

  18. Ehrenreiter K, Kern F, Velamoor V, Meissl K, Galabova-Kovacs G, Sibilia M et al. Raf-1 addiction in Ras-induced skin carcinogenesis. Cancer Cell 2009; 16: 149–160.

    CAS  Article  Google Scholar 

  19. Riva C, Lavieille JP, Reyt E, Brambilla E, Lunardi J, Brambilla C . Differential c-myc, c-jun, c-raf and p53 expression in squamous cell carcinoma of the head and neck: Implication in drug and radioresistance. Eur J Cancer B Oral Oncol 1995; 31: 384–391.

    Article  Google Scholar 

  20. Wimmer R, Baccarini M . Partner exchange: protein-protein interactions in the Raf pathway. Trends Biochem Sci 2010; 35: 660–668.

    CAS  Article  Google Scholar 

  21. Niault TS, Baccarini M . Targets of Raf in tumorigenesis. Carcinogenesis 2010; 31: 1165–1174.

    CAS  Article  Google Scholar 

  22. Flaherty KT, Puzanov I, Kim KB, Ribas A, McArthur GA, Sosman JA et al. Inhibition of mutated, activated BRAF in metastatic melanoma. N Engl J Med 2010; 363: 809–819.

    CAS  Article  Google Scholar 

  23. Bollag G, Hirth P, Tsai J, Zhang J, Ibrahim PN, Cho H et al. Clinical efficacy of a RAF inhibitor needs broad target blockade in BRAF-mutant melanoma. Nature 2010; 467: 596–599.

    CAS  Article  Google Scholar 

  24. Cichowski K, Janne PA . Drug discovery: Inhibitors that activate. Nature 2010; 464: 358–359.

    CAS  Article  Google Scholar 

  25. Brower V . BRAF inhibitors: research accelerates in wake of positive findings. J Natl Cancer Inst 2010; 102: 214–215.

    CAS  Article  Google Scholar 

  26. Poulikakos PI, Zhang C, Bollag G, Shokat KM, Rosen N . RAF inhibitors transactivate RAF dimers and ERK signalling in cells with wild-type BRAF. Nature 2010; 464: 427–430.

    CAS  Article  Google Scholar 

  27. Hatzivassiliou G, Song K, Yen I, Brandhuber BJ, Anderson DJ, Alvarado R et al. RAF inhibitors prime wild-type RAF to activate the MAPK pathway and enhance growth. Nature 2010; 464: 431–435.

    CAS  Article  Google Scholar 

  28. Su F, Viros A, Milagre C, Trunzer K, Bollag G, Spleiss O et al. RAS mutations in cutaneous squamous-cell carcinomas in patients treated with BRAF inhibitors. N Engl J Med 2012; 366: 207–215.

    CAS  Article  Google Scholar 

  29. Indra AK, Warot X, Brocard J, Bornert JM, Xiao JH, Chambon P et al. Temporally-controlled site-specific mutagenesis in the basal layer of the epidermis: comparison of the recombinase activity of the tamoxifen-inducible Cre-ER(T) and Cre-ER(T2) recombinases. Nucleic Acids Res 1999; 27: 4324–4327.

    CAS  Article  Google Scholar 

  30. Ise K, Nakamura K, Nakao K, Shimizu S, Harada H, Ichise T et al. Targeted deletion of the H-ras gene decreases tumor formation in mouse skin carcinogenesis. Oncogene 2000; 19: 2951–2956.

    CAS  Article  Google Scholar 

  31. Dajee M, Lazarov M, Zhang JY, Cai T, Green CL, Russell AJ et al. NF-kappaB blockade and oncogenic Ras trigger invasive human epidermal neoplasia. Nature 2003; 421: 639–643.

    CAS  Article  Google Scholar 

  32. Quintanilla M, Brown K, Ramsden M, Balmain A . Carcinogen-specific mutation and amplification of Ha-ras during mouse skin carcinogenesis. Nature 1986; 322: 78–80.

    CAS  Article  Google Scholar 

  33. Lichtenberger BM, Tan PK, Niederleithner H, Ferrara N, Petzelbauer P, Sibilia M . Autocrine VEGF signaling synergizes with EGFR in tumor cells to promote epithelial cancer development. Cell 2010; 140: 268–279.

    CAS  Article  Google Scholar 

  34. Maurer G, Tarkowski B, Baccarini M . Raf kinases in cancer-roles and therapeutic opportunities. Oncogene 2011; 30: 3477–3488.

    CAS  Article  Google Scholar 

  35. Lock FE, Hotchin NA . Distinct roles for ROCK1 and ROCK2 in the regulation of keratinocyte differentiation. PLoS ONE 2009; 4: e8190.

    Article  Google Scholar 

  36. McMullan R, Lax S, Robertson VH, Radford DJ, Broad S, Watt FM et al. Keratinocyte differentiation is regulated by the Rho and ROCK signaling pathway. Curr Biol 2003; 13: 2185–2189.

    CAS  Article  Google Scholar 

  37. Honma M, Benitah SA, Watt FM . Role of LIM kinases in normal and psoriatic human epidermis. Mol Biol Cell 2006; 17: 1888–1896.

    CAS  Article  Google Scholar 

  38. Karreth FA, Frese KK, Denicola GM, Baccarini M, Tuveson DA . C-Raf is required for the initiation of lung cancer by K-Ras. Cancer Discov 2011; 1: 128–136.

    CAS  Article  Google Scholar 

  39. Blasco RB, Francoz S, Santamaria D, Canamero M, Dubus P, Charron J et al. c-Raf, but not B-Raf, is essential for development of K-Ras oncogene-driven non-small cell lung carcinoma. Cancer Cell 2011; 19: 652–663.

    CAS  Article  Google Scholar 

  40. Ridky TW, Khavari PA . Pathways sufficient to induce epidermal carcinogenesis. Cell Cycle 2004; 3: 621–624.

    CAS  Article  Google Scholar 

  41. Solit DB, Rosen N . Resistance to BRAF inhibition in melanomas. N Engl J Med 2011; 364: 772–774.

    CAS  Article  Google Scholar 

  42. Downward J . Targeting RAF: trials and tribulations. Nat Med 2011; 17: 286–288.

    CAS  Article  Google Scholar 

  43. Montagut C, Sharma SV, Shioda T, McDermott U, Ulman M, Ulkus LE et al. Elevated CRAF as a potential mechanism of acquired resistance to BRAF inhibition in melanoma. Cancer Res 2008; 68: 4853–4861.

    CAS  Article  Google Scholar 

  44. Heidorn SJ, Milagre C, Whittaker S, Nourry A, Niculescu-Duvas I, Dhomen N et al. Kinase-dead BRAF and oncogenic RAS cooperate to drive tumor progression through CRAF. Cell 2010; 140: 209–221.

    CAS  Article  Google Scholar 

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Acknowledgements

We thank Karin Ehrenreiter and the animal house team for excellent technical help, M Sibilia for the K5-SOS-F mice and P Chambon for the K5-Cre-er(T) animals. This work was supported by European Commission grant LSH-CT-2003–506803 and by Austrian Research Fund grant P19530-B11 (to MB).

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Correspondence to M Baccarini.

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Kern, F., Doma, E., Rupp, C. et al. Essential, non-redundant roles of B-Raf and Raf-1 in Ras-driven skin tumorigenesis. Oncogene 32, 2483–2492 (2013). https://doi.org/10.1038/onc.2012.254

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  • DOI: https://doi.org/10.1038/onc.2012.254

Keywords

  • B-Raf
  • conditional ablation
  • epidermis
  • Raf-1
  • Ras-driven skin tumorigenesis

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