Shweta Nayak

Epigenetics in breast cancer: what's new?

Epigenetic changes are critical for development and progression of cancers, including breast cancer. Significant progress has been made in the basic understanding of how various epigenetic changes such as DNA methylation, histone modification, miRNA expression, and higher order chromatin structure affect gene expression. The present review will focus on methylation and demethylation of histones. While the acetylation of histones has been at the forefront of well-characterized post-translational modifications of histones, including the development of inhibitors targeting de-acetylating enzymes, the past few years have witnessed a dramatic increase in knowledge regarding the role of histone methylation/demethylation. This is an exciting and rapidly evolving area of research, with much promise for potential clinical intervention in several cancers including breast cancer. We also summarize efforts to identity DNA methylation signatures that could be prognostic and/or predictive markers in breast cancer, focusing on recent studies using genome-wide approaches. Finally, we briefly review the efforts made by both the National Institutes of Health Epigenome Project and The Cancer Genome Atlas, especially highlighting the study of breast cancer epigenetics, exciting technological advances, potential roadblocks, and future directions.

Random-start gonadotropin-releasing hormone (GnRH) antagonist–treated cycles with GnRH agonist trigger for fertility preservation

OBJECTIVE To describe our experience with random-start IVF with the use of GnRH agonist for final oocyte maturation, to reduce the risk of ovarian hyperstimulation syndrome. DESIGN Case series. SETTING University-based center for reproductive endocrinology and infertility. PATIENT(S) Patients with a new diagnosis of cancer who presented with a narrow time frame for IVF before initiating cancer therapy. INTERVENTION(S) Random-start GnRH antagonist cycles with GnRH agonist trigger for final oocyte maturation. MAIN OUTCOME MEASURE(S) Number of oocytes retrieved, fertilization rate, rates of ovarian hyperstimulation syndrome. RESULTS Cycles were started in the late follicular or luteal phase, and the duration of controlled ovarian hyperstimulation ranged between 8-13 days. A total of 14-40 oocytes were retrieved and 5-20 embryos cryopreserved for each patient. CONCLUSION(S) Random-start IVF is a reasonable option for fertility preservation in those cancer patients for whom the treatment window may be narrow. In addition, the use of a GnRH agonist for final oocyte maturation may decrease the potential risk of ovarian hyperstimulation syndrome.

Epigenetic reprogramming of HOXC10 in endocrine-resistant breast cancer.

Genome-wide screen identifies methylation of the estrogen-repressed HOXC10 gene as a determinant of resistance to aromatase inhibitors in breast cancer. Playing Tug-of-War with HOXC10 Aromatase inhibitors are drugs that prevent androgens from being converted into estrogen, and they are frequently used to treat breast cancers that express the estrogen receptor. Unfortunately, some patients’ tumors never respond to these drugs, and others gradually become resistant over time. Although the development of resistance to aromatase inhibitors has been investigated in some previous studies and some potential mechanisms have been proposed, much about this process remains unknown. Pathiraja and colleagues began by performing a genome-wide methylation screen in breast cancer cells, which identified the developmental gene HOXC10 as a target of epigenetic silencing in the context of long-term estrogen withdrawal. When HOXC10 is active, it interferes with proliferation and can stimulate apoptosis, but estrogen suppresses its activity, thereby promoting tumor growth. By decreasing estrogen production, aromatase inhibitors up-regulate HOXC10, accounting for some of their antitumor activity. However, long-term estrogen deprivation eventually has the opposite effect, leading to methylation of HOXC10 and its long-term suppression even in the absence of estrogen. These findings suggest that a rational approach for overcoming aromatase resistance in breast cancer may involve the addition of demethylating drugs to overcome the methylation of HOXC10 and take advantage of its antitumor effects, although this remains to be demonstrated directly. Resistance to aromatase inhibitors (AIs) is a major clinical problem in the treatment of estrogen receptor (ER)–positive breast cancer. In two breast cancer cell line models of AI resistance, we identified widespread DNA hyper- and hypomethylation, with enrichment for promoter hypermethylation of developmental genes. For the homeobox gene HOXC10, methylation occurred in a CpG shore, which overlapped with a functional ER binding site, causing repression of HOXC10 expression. Although short-term blockade of ER signaling caused relief of HOXC10 repression in both cell lines and breast tumors, it also resulted in concurrent recruitment of EZH2 and increased H3K27me3, ultimately transitioning to increased DNA methylation and silencing of HOXC10. Reduced HOXC10 in vitro and in xenografts resulted in decreased apoptosis and caused antiestrogen resistance. Supporting this, we used paired primary and metastatic breast cancer specimens to show that HOXC10 was reduced in tumors that recurred during AI treatment. We propose a model in which estrogen represses apoptotic and growth-inhibitory genes such as HOXC10, contributing to tumor survival, whereas AIs induce these genes to cause apoptosis and therapeutic benefit, but long-term AI treatment results in permanent repression of these genes via methylation and confers resistance. Therapies aimed at inhibiting AI-induced histone and DNA methylation may be beneficial in blocking or delaying AI resistance.

Vaginal Foreign Body: A Delayed Diagnosis

BACKGROUND To describe a case of prolonged vaginal bleeding in a prepubertal girl. Review of medical record and literature search. CASE A 7-year-old female was referred to our pediatric and adolescent gynecologic clinic for evaluation of vaginal bleeding and ovarian cyst on ultrasonography. Her parents denied any history of trauma or sexual abuse. Initial evaluation revealed pre-pubertal luteinizing hormone and follicle stimulating hormone levels, and follow-up ultrasonography revealed normal pre-pubertal pelvic anatomy. However, a skeletal survey, which was obtained to assess for the presence of skeletal fibrous dysplasia, revealed a metal spring in the vagina. The patient ultimately underwent an exam under anesthesia and vaginoscopy with removal of 3 foreign bodies, with subsequent termination of symptoms. SUMMARY AND CONCLUSIONS In cases of pre-pubertal vaginal bleeding, the possibility of vaginal foreign body should not be excluded despite normal sonographic imaging. If clinical suspicion for a vaginal foreign body persists, additional imaging modalities or exam under anesthesia should be considered.

A Role for Histone H2B Variants in Endocrine-Resistant Breast Cancer

Acquired resistance to aromatase inhibitors (AIs) remains a major clinical problem in the treatment of estrogen receptor-positive (ER+) breast cancer. We and others have previously reported widespread changes in DNA methylation using breast cancer cell line models of endocrine resistance. Here, we show that the histone variant HIST1H2BE is hypomethylated in estrogen deprivation-resistant C4-12 and long-term estrogen-deprived (LTED) cells compared with parental MCF-7 cells. As expected, this hypomethylation associates with increased expression of HIST1H2BE in C4-12 and LTED cells. Both overexpression and downregulation of HIST1H2BE caused decreased proliferation in breast cancer cell lines suggesting the need for tightly controlled expression of this histone variant. Gene expression analysis showed varied expression of HIST1H2BE in a large panel of breast cancer cell lines, without restriction to specific molecular subtypes. Analysis of HIST1H2BE messenger RNA (mRNA) expression in ER+ AI-treated breast tumors showed significantly higher expression in resistant (n = 19) compared with sensitive (n = 37) tumors (p = 0.01). Using nanostring analysis, we measured expression of all 61 histone variants in endocrine-resistant and endocrine-sensitive tumors. We found significant overexpression of 22 variant histone genes in tumors resistant to AI therapy. In silico The Cancer Genome Atlas (TCGA) analysis showed frequent amplification of the HIST1 locus. In summary, our studies show, for the first time, that overexpression of histone variants might be important in endocrine response in ER+ breast cancer, and that overexpression is at least in part mediated via epigenetic mechanisms and amplifications. Future studies addressing endocrine response should include a potential role of these currently understudied histone variants.

Adolescent gynecology: special considerations for special patients.

Developments in the field of adolescent gynecology highlight the specific expertise and care required by this population. Given the ability to shape their future health choices, adolescents are a critical target for preventative health care. The approach to the evaluation and management of this unique population rests not only on the practitioners adept ability to recognize the unique clinical challenges that may occur, but also rests on his/her understanding of these problems. Here, we review recent guidelines and practice patterns in the evaluation and management of issues in adolescent gynecology.

Progesterone level at oocyte retrieval predicts in vitro fertilization success in a short-antagonist protocol: a prospective cohort study

OBJECTIVE To evaluate the distribution of P levels on the day of oocyte retrieval as it relates to pregnancy outcome in an antagonist protocol, which may be at higher risk for elevated P levels. DESIGN Prospective cohort study. SETTING Academic IVF center. PATIENT(S) One hundred eighty-six women undergoing controlled ovarian hyperstimulation with an antagonist protocol. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Implantation, pregnancy, and spontaneous abortion rates were collected. RESULT(S) Implantation rate (positive hCG 14 days after ET) and pregnancy rate were significantly higher when the P level was <12 ng/mL on the day of oocyte retrieval. Miscarriage rates were higher when the P level was ≥12 ng/mL, although this did not reach statistical significance. CONCLUSION(S) Elevated P on the day of oocyte retrieval is associated with significantly lower implantation and ongoing pregnancy rates. This is the first study to date to both uncover the distribution of P on the day of oocyte retrieval in an antagonist cycle and determine the impact an elevation may have on pregnancy outcome.

The Rise and Fall of Oogonial Stem Cells Within the Historical Context of Adult Stem Cells

For decades, it has been believed that adult human female reproductive potential was determined by a finite number of primordial follicles, which are established in the embryonic gonad. The rise of adult stem cells in other organs inevitably led to investigations that searched for stem cells in various organs of the reproductive tract, including ovaries, endometrium, and uterus. Within ovaries, somatic stem cells that drive granulosa cell proliferation and provide an essential support environment for differentiating oocytes have been characterized with little controversy. No adult stem cell claim has stirred as much controversy as the one that oogonial stem cells exist and can give rise to neo-oogenesis. Such a finding would render women, previously believed to have a nonrenewable gamete supply, remarkably more like men, who are able to replenish their germ cells. We review the rise and fall of oogonial stem cells in the historical context of the general concept of adult stem cells.