Hormonal therapy in endometrial carcinoma

Chromatin composition alterations and the critical role of MeCP2 for epigenetic silencing of progesterone receptor-B gene in endometrial cancers

OBJECTIVE

To understand the epigenetic mechanism underlying the PR-B gene silencing in endometrial cancer (EC) cells, we compared the chromatin composition between transcriptionally active and silenced PR-B genes in EC cell lines and cancer tissues.

METHODS

Chromatin Immunoprecipitation (ChIP) assay was performed to measure MBD occupancy and histone acetylation/methylation in transcriptionally active and silenced PR-B genes. PR-B-positive/-negative, as well as epigenetic inhibitor-treated/-untreated EC cells were used as study models. Real-time polymerase chain reaction (PCR) and Western blot analysis were applied to measure the mRNA and protein levels of PR-B, MBD, and histones.

RESULTS

A close association among PR-B methylation, MBD binding and PR-B gene silencing was observed. Treatment with epigenetic inhibitors led to dynamic changes in the PR-B chromatin composition and gene expression. Increased H3/H4 acetylation and H3-K4 methylation, and decreased H3-K9 methylation were found to be associated with re-activation of silenced PR-B genes. MeCP2 knockdown resulted in a decreased MeCP2 binding to PR-B genes and an increased PR-B expression. ChIP analysis of MeCP2 binding to PR-B genes in the PR-B-positive/-negative EC samples confirmed the significant role of MeCP2 in PR-B silencing.

CONCLUSION

PR-B gene expression is regulated by a concerted action of epigenetic factors including DNA methylation, MBD binding, and histone modifications. MeCP2 occupancy of PR-B genes plays a critical role in PR-B gene silencing. These findings enriched our knowledge of the epigenetic regulation of PR-B expression in EC, and suggested that the epigenetic re-activation of PR-B could be explored as a potential strategy to sensitize the PR-B-negative endometrial cancers to progestational therapy.

Application of DNA methylation biomarkers for endometrial cancer management

It has become clear that aberrant gene expression, via alterations in promoter methylation or histone acetylation, is a contributing factor for carcinogenesis, perhaps as important as genetic mutation. This is particularly evident in endometrial cancer, in which multiple genes are silenced through hypermethylation. In this review, we discuss the field of epigenetics and relevant techniques to characterize methylation and acetylation alterations. The CpG island methylator phenotype, epimutations and the effects of aging on methylation are also discussed. In endometrial cancer there is evidence that hypermethylation of relevant genes can be reversed using epigenetic inhibitors, resulting in re-expression of silenced genes. Preliminary data also suggest that a panel of methylation biomarkers could be useful for diagnosis and even screening in selected populations at high risk. This disease is particularly well suited for such a strategy given that the endometrium is readily accessible for testing and endometrial cancer precursors are well defined.

Histone deacetylase inhibitors induce apoptosis in both Type I and Type II endometrial cancer cells

OBJECTIVE

To characterize the molecular pathways involved in apoptosis following administration of histone deacetylase inhibitors to Type I and II endometrial cancer cells.

METHODS

Ark2, Ishikawa, and AN3 cell lines representing both Type I and II endometrial cancers were treated with various concentrations of oxamflatin and HDAC inhibitor-1. Cell apoptosis was determined by flow cytometry, nuclear staining, Western blotting, and mitochondrial membrane potential assays.

RESULTS

Compared to controls, there was a 95% reduction in the growth of Ark2 cells following administration of histone deacetylase inhibitors and this response was dose-dependent. These agents also caused profound morphologic changes and loss of mitochondrial membrane potentials consistent with the induction of apoptosis. Cleavage of PARP, caspase-9, and caspase-8 was detected, confirming the activation of apoptotic cascades in endometrial carcinoma cells. This effect was present in both serous and endometrioid cell types.

CONCLUSION

Our results suggest that oxamflatin and HDAC inhibitor-1 have potent cytotoxicity in endometrial cancer cells by inducing cell apoptosis. Histone deacetylase inhibitors are promising agents for the treatment of both Type I and II endometrial carcinoma.

Fulvestrant: A Further Treatment Option for Patients with Metastatic Uterine Cancer?

BACKGROUND

Metastatic uterine cancer is notoriously difficult to treat, presenting a poor prognosis and a median survival time of less than 1 year. We present the successful use of the antiestrogen fulvestrant in an endocrine therapy-naive patient with advanced uterine cancer.

CASE REPORT

A 64-year-old female presented with advanced uterine cancer 7.0 x 6.0 x 5.5 cm in size, with infiltration of the bladder. Previous chemotherapy and radiotherapy had been unsuccessful in preventing disease progression, and the patient developed hepatic metastases. As the tumor expressed a high level of estrogen receptor, treatment with fulvestrant 250 mg/month was initiated.

RESULTS

25 months after commencing fulvestrant treatment, the tumor had decreased in size to 4.8 x 3.5 x 3.2 cm, and the hepatic metastases were no longer detectable. Throughout treatment, the patient maintained a Karnofsky performance index of 90%.

CONCLUSION

We suggest that fulvestrant may be an active and well-tolerated treatment option for patients with estrogen receptor- positive advanced uterine cancer.

Radical pelvic resection and intraoperative radiation therapy for recurrent endometrial cancer: Technique and analysis of outcomes

OBJECTIVE

To describe the technique and assess outcomes and morbidity following radical resection combined with intraoperative electron radiation therapy (IOERT) in patients with recurrent endometrial cancer.

METHODS

From 1986 to 2002, 25 patients received treatment including radical resection and IOERT for recurrent endometrioid, endometrial cancer. Relevant clinical information was extracted through retrospective chart review.

RESULTS

Treatment prior to referral included radiation in 56% and either a secondary surgery or chemotherapy in 48%. External radiation (EBRT) was administered in addition to IOERT in 84%. Radical procedures performed at the time of IOERT included resection of the pelvic sidewall en bloc with the obturator nerve, external iliac vein, psoas, iliacus, or obturator internus muscles, ureter, or boney ileum. Seven patients required exenteration in combination with resection of the pelvic sidewall. The median IOERT dose was 1500 cGy (range 1000-2500 cGy). Overall five-year survival was 47% vs. 71% for those with a gross total resection but close margins. Two patients with recurrences limited to the para-aortic area are alive without evidence of disease at 54 and 71 months. Proportional hazards modeling showed concurrent EBRT, tumor size after resection, grade, and age to be associated with improved survival. The most common complications were peripheral neuropathy, functional ureteral obstruction, and fistula formation.

CONCLUSIONS

With an aggressive treatment approach including radical resection combined with IOERT, long-term survival is possible in a significant number of patients with localized recurrent endometrial cancer. Preoperative radiation paired with complete surgical resection utilizing extended procedures is paramount to achieving optimal outcomes.

Steroid hormones and cancer: (III) observations from human subjects

Epidemiological evidence strongly suggests that steroid hormones are implicated in the risk of cancers of the breast, ovary and endometrium. However, it has proved difficult to implicate specific hormones or show that measurement of circulating hormones can identify women who will go on to develop malignant disease. There are, however, more convincing data that a proportion of established cancers are dependent upon steroid hormones for their continued growth and these underpin the use of endocrine manoeuvres in the treatment of these malignancies. Increased knowledge of the synthesis, release and mechanism of action of steroid hormones has led to the development of novel therapies for endocrine sensitive cancer and on-going research can reasonably be expected to identify tumour markers which can accurately predict hormone-dependency and provide better understanding of the mechanism by which response and resistance to therapy occur. The hope is that this knowledge will translate into more effective and rational endocrine treatment benefiting increased numbers of patients.