Abstract 2882: Therapeutic effects of ormeloxifene on cervical cancer

Abstract

Abstract Background: Cervical cancer is one of the most common and deadly cancers among women worldwide and is strongly associated with persistent Human Papillomavirus (HPV) infection. HPV E6/E7 oncoproteins are well known to interfere with p53 and retinoblastoma (Rb) proteins and drive the development of cervical cancer. While screening for cervical cancer can reduce the incidence and mortality, treatment of advanced stage cervical cancer is difficult and often unsuccessful. Therefore, there is an urgent need for the development of additional treatment modalities. Ormeloxifene is a non-hormonal anti-estrogen oral contraceptive for human use and it effectively suppresses the highly proliferative decidual cells in the endometrium to inhibit egg implantation. Considering its strong anti-proliferative effect, we hypothesized that ormeloxifene may inhibit the growth of cervical cancer cells and may suppress the expression of HPV oncoproteins E6/E7. Methods: The effect of ormeloxifene on the proliferation of various cervical cancer cell lines (Caski, SiHa, C33A, and HT3) was determined by MTS and colony formation assay. Annexin V/7AAD and propidium iodide (PI) staining was analyzed by flow cytometry to determine ormeloxifene's effect on apoptosis and cell cycle inhibition, respectively. The expression of apoptotic proteins such as poly (ADP-ribose) polymerase (PARP), Caspase 3 and Caspase 9 was determined by immunoblotting. The potential of ormeloxifene to repress the expression of HPV E6/E7 oncogenes was determined by quantitative RT-PCR and immunoblotting analyses. Further, the efficacy of ormeloxifene to restore tumor suppressor proteins, such as p53 and Rb, was also determined by immunoblotting. Results: In all 4 cell lines, ormeloxifene effectively inhibited cervical cancer cell growth. Ormeloxifene treatment induced apoptosis in cervical cancer cells as determined by staining for Annexin V/7AAD and immunoblotting for cleaved PARP, Caspase 3, and Caspase 9. PI staining also clearly revealed that ormeloxifene treatment arrests Caski cells in the G0-G1 phase. Additionally, ormeloxifene treatment caused a marked decrease in the levels of HPV E6 and E7 oncogenes and restored the levels of p53 and Rb proteins in Caski cells. Conclusion: Our findings show that ormeloxifene significantly inhibits cervical cancer cell growth and down-regulates HPV E6/E7 oncogenes, therefore; ormeloxifene may be novel chemo-preventive and treatment method for the management of cervical cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2882. doi:1538-7445.AM2012-2882