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Parvesh Chaudhry and Eric Asselin

Endometrial cancer is the most common gynecological malignancy in developed countries and represents the eighth leading cause of cancer related death in women. The growing incidence of endometrial cancer leads scientists and oncologists to identify effective preventive measures and also molecular markers for diagnosis and prognosis. Chemotherapy and hormone therapy is the mainstay treatment option for advanced and recurrent endometrial cancer and response to therapy is one of the most important factor which favors prognosis and overall survival. In recent years, there have been major advances in the treatment of patients with endometrial cancer. Despite advances made in the treatment of this cancer, the overall survival of patients has not significantly improved because considerable number of patients harbor tumor refractory to these therapies and the majority of the initially responsive tumors become refractory to treatments. Therefore, determination of sensitivity/resistance is becoming increasingly important for individualization of endometrial cancer therapy. The aim of this review is to present the existing knowledge about the molecular markers that could play a crucial role in determining resistance to chemo- and hormone therapy. Extensive literature search for the cell signaling pathways and factors responsible for chemoresistance have been performed and reviewed. Several recent studies suggest that deregulations in the apoptotic pathways (such as p53, Fas/FasL, Bcl-2 family proteins, inhibitor of apoptosis proteins), survival pathways (PI3K/AKT, MAPK), hormone receptor signaling pathways (progesterone receptor), Cyclooxygenase-2 and Her-2 are considered as key factors involved in the onset and maintenance of therapeutic resistance, suggesting that resistance is a multi-factorial phenomenon.

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Céline Van Themsche, Sophie Parent, Valérie Leblanc, Caroline Descôteaux, Anne-Marie Simard, Gervais Bérubé and Eric Asselin

We have previously reported the synthesis of VP-128, a new 17β-oestradiol (E2)-linked platinum(II) hybrid with high affinity for oestrogen receptor α (ERα). In the present study, we have investigated the anti-tumour activity of VP-128 towards breast cancer cells in vitro and in vivo. We used human ERα-positive (MCF-7) and -negative (MDA-MB-468) cells as a model for treatment with increasing doses of VP-128, cisplatin or E2 in vitro and for xenograft experiments in nude mice in vivo. Compared with cisplatin, VP-128 showed markedly improved in vitro and in vivo anti-tumour activity towards ERα-positive MCF-7 breast cancer cells, without increased systemic toxicity. In these caspase-3-deficient cells, treatment with VP-128 overcame weak cellular sensitivity to cisplatin in vitro and in vivo. In these cells, only the hybrid induced apoptosis in an ERα-dependent manner, inactivated both X-linked inhibitor of apoptosis protein and Akt, and induced selective nuclear accumulation of ERα and the expression of ER-regulated genes c- myc and tff1, which was blocked by ERα-specific antagonist ICI 282 780. In the case of ERα-negative MDA-MB-468 cells, VP-128, but not cisplatin, induced nuclear accumulation of apoptosis-inducing factor and inhibited c- myc expression. However, VP-128 did not show enhanced in vivo anti-tumour activity compared with cisplatin. These results reveal two different modes of action for VP-128 in ERα-positive and -negative breast cancer cells, and highlight the promising therapeutic value of this unique E2-platinum hybrid for selective targeting of hormone-dependent cancers.