Antitumor Pharmacology

Growth suppression and radiosensitivity increase by HMGB1 in breast cancer

Article metrics

Abstract

Aim:

HMGB1 (high-mobility group box-1) is a nuclear protein containing a consensus RB (retinoblastoma)-binding LXCXE motif. In this study, we studied the potential association of HMGB1 and RB and the in vitro and in vivo activities of HMGB1 in human breast cancer cells.

Methods:

The protein-protein interaction was determined by immunoprecipitation-Western blotting and glutathione-S-transferase capture assays; cell growth and radiosensitivity were examined by cell counts, MTT assay, and clonogenic assay; cell cycle progression and apoptosis were evaluated using flow cytometry; and the antitumor activity of HMGB1 was examined with tumor xenografts in nude mice.

Results:

HMGB1 was associated with RB via a LXCXE motif-dependent mechanism. HMGB1 enhanced the ability of RB for E2F and cyclin A transcription repression. The increased expression of HMGB1 conferred an altered phenotypes characterized by the suppression of cell growth; G1 arrest and apoptosis was induced in MCF-7 cells containing the wild-type retinoblastoma (Rb) gene, but showed no activities in BT-549 cells containing the Rb gene deletion. The HMGB1-induced apoptosis accompanied by caspase 3 activation and PARP (poly(ADP-ribose)polymerase) cleavage. HMGB1 elevated the radiosensitivity of breast cancer cells in both the MCF-7 and BT-549 cell lines. The enhanced expression of HMGB1 caused a suppression of growth of MCF-7 tumor xenografts in nude mice, while LXCXE-defective HMGB1 completely lost antitumor growth activity.

Conclusion:

HMGB1 functions as a tumor suppressor and radiosensitizer in breast cancer. A HMGB1-RB interaction is critical for the HMGB1-mediated transcriptional repression, cell growth inhibition, G1 cell cycle arrest, apoptosis induction, and tumor growth suppression, but is not required for radiosensitization. Therefore, it may be possible to design new therapies for the treatment of breast cancer that exert their effects by modulating the HMGB1 and RB regulatory pathway and HMGB1-related gene therapy.

References

  1. 1

    Yang H, Wang H, Czura CJ, Tracey KJ . HMGB1 as a cytokine and therapeutic target. J Endotoxin Res 2002; 8: 469–72.

  2. 2

    Wang H, Tracey KJ . High mobility group box 1 (HMGB1). Crit Care Med 2005; 33: S472–4.

  3. 3

    Brezniceanu ML, Volp K, Bosser S, Solbach C, Lichter P, Joos S, et al. HMGB1 inhibits cell death in yeast and mammalian cells and is abundantly expressed in human breast carcinoma. FASEB J 2003, 17: 1295–7.

  4. 4

    Classon M, Harlow E . The retinoblastoma tumour suppressor in development and cancer. Nat Rev Cancer 2002; 2: 910–7.

  5. 5

    van Deursen JM . Rb loss causes cancer by driving mitosis mad. Cancer Cell 2007; 11: 1–3.

  6. 6

    Delston RB, Harbour JW . Rb at the interface between cell cycle and apoptotic decisions. Curr Mol Med 2006; 6: 713–8.

  7. 7

    Stevaux O, Dyson NJ . A revised picture of the E2F transcriptional network and RB function. Curr Opin Cell Biol 2002; 14: 684–91.

  8. 8

    Helt AM, Galloway DA . Mechanisms by which DNA tumor virus oncoproteins target the Rb family of pocket proteins. Carcino-genesis 2003; 24: 159–69.

  9. 9

    Gabellini C, Del Bufalo D, Zupi G . Involvement of RB gene family in tumor angiogenesis. Oncogene 2006; 25: 5326–32.

  10. 10

    De Falco G, Giordano A . pRb2/p130: a new candidate for retinoblastoma tumor formation. Oncogene 2006; 25: 5333–40.

  11. 11

    Fan S, Yuan R, Ma Y, Xiong J, Meng Q, Erdos MR, et al. Disruption of the BRCA1 LXCXE motif alters BRCA1 function activity and regulation of RB family but not RB protein binding. Oncogene 2001; 20: 4827–41.

  12. 12

    Fan S, Gao M, Meng Q, Laterra JJ, Symons MH, Coniglio S, et al. Role of NF-kappaB signaling in hepatocyte growth factor/scatter factor-mediated cell protection. Oncogene 2005; 24: 1749–66.

  13. 13

    Fan S, Ma Y, Wang C, Yuan R, Xiong J, Meng Q, et al. Role of direct interaction in BRCA1 inhibition of estrogen receptor activity. Oncogene 2001; 20: 77–87.

  14. 14

    Koh DW, Dawson TM, Dawson VL . Mediation of cell death by poly (ADP-ribose) polymerase-1. Pharmacol Res 2005; 52: 5–14.

  15. 15

    Rosen A, Casciola-Rosen L . Macromolecular substrates for the ICE-like proteases during apoptosis. J Cell Biochem 1997; 64: 50–4.

  16. 16

    Pietilainen T, Lipponen P, Aaltomaa S, Eskelinen M, Kosma VM, Syrjänen K . Expression of retinoblastoma gene protein (Rb) in breast cancer as related to established prognostic factors and survival. Eur J Cancer 1995; 31A: 329–33.

  17. 17

    Oesterreich S, Fuqua SA . Tumor suppressor genes in breast cancer. Endocr Relat Cancer 1999; 6: 405–19.

  18. 18

    Chano T, Kontani K, Teramoto K, Okabe H, Ikegawa S . Truncating mutations of RB1CC1 in human breast cancer. Nat Genet 2002; 31: 285–8.

  19. 19

    Borg A, Zhang QX, Alm P, Olsson H, Sellberg G . The retinoblastoma gene in breast cancer: allele loss is not correlated with loss of gene protein expression. Cancer Res 1992; 2: 2991–4.

  20. 20

    Ceccarelli C, Santini D, Chieco P, Taffurelli M, Gamberini M, Pileri SA, et al. Retinoblastoma (RB1) gene product expression in breast carcinoma. Correlation with Ki-67 growth fraction and biopathological profile. J Clin Pathol 1998; 51: 818–24.

  21. 21

    Malumbres M, Barbacid M . To cycle or not to cycle: a critical decision in cancer. Nat Rev Cancer 2001; 1: 222–31.

  22. 22

    Dai H, van't Veer L, Lamb J, He YD, Mao M, Fine BM, et al. A cell proliferation signature is a marker of extremely poor outcome in a subpopulation of breast cancer patients. Cancer Res 2005; 65: 4059–66.

Download references

Author information

Correspondence to Sai-jun Fan.

Additional information

This work was supported by the National Natural Science Foundation of China (No 30128018), the Natural Science Foundation of Jiangsu Province (No 03KJA180121), the Medical Development Foundation of Soochow University (No EE126506), and the USA National Institutes of Health (No ES013199).

Rights and permissions

Reprints and Permissions

About this article

Keywords

  • HMGB1
  • RB
  • breast cancer
  • cell growth

Further reading