Rosalind Glasspool

Lack of Telomerase Gene Expression in Alternative Lengthening of Telomere Cells Is Associated with Chromatin Remodeling of the hTR and hTERT Gene Promoters

The presence of active telomere maintenance mechanisms in immortal cells allows the bypass of senescence by maintaining telomere length. In most immortal cell lines and tumors, telomere maintenance is attributable to telomerase reactivation. However, a number of immortal cell lines and tumors can achieve telomere maintenance in the absence of detectable telomerase activity by the alternative lengthening of telomere (ALT) mechanism. Epigenetic mechanisms have been implicated in the regulation of telomerase expression. We show that specific modifications within the chromatin environment of the hTR and hTERT promoters correlate with expression of hTR and hTERT in ALT, normal and telomerase-positive tumor cell lines. Lack of expression of hTR and hTERT in ALT cell lines is associated with histone H3 and H4 hypoacetylation and methylation of Lys9 histone H3. Conversely, hTR and hTERT expression in telomerase-positive cell lines is associated with hyperacetylation of H3 and H4 and methylation of Lys4 H3. Methylation of Lys20 H4 was not linked to gene expression but instead was specific to the hTR and hTERT promoters of ALT cells. This may provide an insight into the differences between ALT and telomerase-positive cells as well as a novel marker for the ALT phenotype. Treatment of normal and ALT cells with 5-azadeoxycytidine in combination with Trichostatin A caused chromatin remodeling of both promoters and reactivation of hTR and hTERT expression in ALT and normal cell lines. This data establishes a definite link between the chromatin environment of the telomerase gene promoters and transcriptional activity.

Telomerase-specific suicide gene therapy vectors expressing bacterial nitroreductase sensitize human cancer cells to the pro-drug CB1954.

Telomerase activation is considered to be a critical step in cancer progression due to its role in cellular immortalization. The prevalence of telomerase expression in human cancers makes it an attractive candidate for new mechanism-based targets for cancer therapy. The selective killing of cancer cells can be achieved by gene-directed enzyme pro-drug therapy (GDEPT). In this study we have tested the feasibility of using the transcriptional regulatory sequences from the hTERT and hTR genes to regulate expression of the bacterial nitroreductase enzyme in combination with the pro-drug CB1954 in a suicide gene therapy strategy. hTERT and hTR promoter activity was compared in a panel of 10 cell lines and showed a wide distribution in activity; low activity was observed in normal cells and telomerase-negative immortal ALT cell lines, with up to 300-fold higher activity observed in telomerase positive cancer lines. Placing the nitroreductase gene under the control of the telomerase gene promoters sensitized cancer cells in tissue culture to the pro-drug CB1954 and promoter activity was predictive of sensitization to the pro-drug (2–20-fold sensitization), with cell death restricted to lines exhibiting high levels of promoter activity. The in vivo relevance of these data was tested using two xenograft models (C33a and GLC4 cells). Significant tumour reduction was seen with both telomerase promoters and the promoter-specific patterns of sensitization observed in tissue culture were retained in xenograft models. Thus, telomerase-specific suicide gene therapy vectors expressing bacterial nitroreductase sensitize human cancer cells to the pro-drug CB1954.

Does body mass index affect progression-free or overall survival in patients with ovarian cancer? Results from SCOTROC I trial

BACKGROUND Previous studies have indicated an association between obesity and poor survival in several tumour types, including ovarian cancer. We sought to test the hypothesis that obesity reduces survival in a large, well-characterised and relatively homogeneous cohort of ovarian cancer patients. PATIENTS AND METHODS The relationship between body mass index (BMI) and overall survival (OS) and progression-free survival (PFS) in 1067 patients participating in the Scottish Randomised Trial in Ovarian Cancer I trial was assessed. All patients received first-line carboplatin/taxane chemotherapy. The dose of carboplatin was determined by a measured glomerular filtration rate (GFR), ensuring accurate dosing in all categories of BMI and the dose of taxane was not capped. Patients were assigned to one of four categories: underweight (BMI < 18.5), ideal weight (BMI 18.5-24.9), overweight (BMI 25-29.9) or obese (BMI >or= 30). RESULTS There were neither statistically significant differences in PFS or OS between these four groups nor were there any differences in taxane or carboplatin dose intensity. Furthermore, there was no association between BMI and tumour stage or grade at presentation, or completeness of debulking surgery. CONCLUSIONS Obese patients with epithelial ovarian cancer do not have a poorer prognosis, provided that they receive optimal doses of chemotherapy based on measured GFR and actual body weight.

Telomerase-directed molecular therapeutics

The management of malignant disease remains one of the most challenging areas of modern medicine. The lifetime risk of developing cancer in the western world is estimated to be as high as 1 in 3. Traditionally, surgery, chemotherapy and radiotherapy have been the primary choice of treatment for patients with malignant tumours. Despite advances in the use and development of conventional cytotoxic agents, the cure rate remains disappointing in most patients with advanced disease of the common solid tumours. Consequently, the development of novel anti-cancer therapies is a high priority in cancer medicine. In recent years, a new generation of cancer therapies has emerged, based on a growing understanding of the molecular events that contribute to malignant transformation. A major difference between normal and cancer cells is the ability of cancer cells to multiply in an unrestricted and ungoverned fashion. In this context, there is considerable interest in elucidating the mechanisms that allow this unrestricted proliferation and that ultimately result in immortal cancer cells. It is now clear that the enzyme telomerase confers immortality on cells in most types of cancer. With the cancer cell reliant on telomerase for its survival, telomerase represents an extremely attractive mechanism-based target for the development of new cancer therapeutics.

Telomerase and cancer: time to move from a promising target to a clinical reality

The past 25 years have seen unparalleled advances in our understanding of the molecular basis of cancer. As a result, novel molecular targets have been identified that provide great potential for the development of new cancer diagnostics and therapies. Four key features of cancer cells distinguish them from their normal counterparts: loss of cell‐cycle regulation, loss of control over invasion and metastasis, failure of apoptotic mechanisms, and bypass of senescence. This review examines our understanding of the bypass of senescence and the process of immortalization during carcinogenesis. In addition, the realistic opportunities for telomerase in cancer diagnostics and the challenges faced in clinical trial design for telomerase therapeutics are discussed. Copyright

Gynecologic Cancer InterGroup (GCIG) consensus review for clear cell carcinoma of the ovary

Abstract Clear cell carcinoma of the ovary (CCC) is a histologic subtype of epithelial ovarian cancer with a distinct clinical behavior. There are marked geographic differences in the prevalence of CCC. The CCC is more likely to be detected at an early stage than high-grade serous cancers, and when confined within the ovary, the prognosis is good. However, advanced disease is associated with a very poor prognosis and resistance to standard treatment. Cytoreductive surgery should be performed for patients with stage II, III, or IV disease. An international phase III study to compare irinotecan/cisplatin and paclitaxel/carboplatin as adjuvant chemotherapy for stage IIV CCC has completed enrollment (GCIG/JGOG3017). Considering the frequent PIK3CA mutation in CCC, dual inhibitors targeting PI3K, AKT in the mTOR pathway, are promising. Performing these trials and generating the evidence will require considerable international collaboration.

Gynecologic Cancer InterGroup (GCIG) consensus review for uterine and ovarian carcinosarcoma.

Abstract Carcinosarcomas (also known as malignant mixed müllerian tumors) are rare and highly aggressive epithelial malignancies that contain both malignant sarcomatous and carcinomatous elements. Uterine carcinosarcomas (UCs) are uncommon with approximately more than 35% presenting with extra uterine disease at diagnosis. Up to 90% ovarian carcinosarcomas (OCs) will have disease that has spread beyond the ovary. Prognosis for localized stage disease is poor with a high risk of recurrences, both local and distant, occurring within 1 year. The survival of women with advanced UC or OC is worse than survival of endometrioid or high-grade serous histologies. No improvement in survival rates has been observed in the past few decades with an overall median survival of less than 2 years. Currently, there is no clear evidence to establish consensus guidelines for therapeutic management of carcinosarcomas. Until recently, gynecological carcinosarcomas were considered as a subtype of sarcoma and treated as such. However, carcinosarcomas are now known to be metaplastic carcinomas and so should be treated as endometrial or ovarian high-risk carcinomas, despite the lack of specific data. For UCs, a comprehensive approach to management is recommended with complete surgical staging followed by systemic chemotherapy in patients with both early and advanced stage disease. Active agents include paraplatin, cisplatin, ifosfamide, and paclitaxel. The combination of carboplatin-paclitaxel is the most commonly used regimen in the adjuvant and advanced setting. Adjuvant radiotherapy (external beam irradiation and/or vaginal brachytherapy) has not shown any overall survival benefit but has been reported to decrease local recurrences. For OCs and for other ovarian epithelial cancer, the mainstay of treatment remains cytoreductive surgical effort followed, even in early stage, by platinum-based chemotherapy, usually carboplatin-paclitaxel.

Gynecologic cancer intergroup (GCIG) consensus review for ovarian sex cord stromal tumors

Sex cord stromal tumors (SCST) are rare cancers of the ovarian area in adults. They constitute a heterogeneous group of tumors that develop from the sex cords and the ovarian stroma. These tumors are detected typically at an early stage, and they may recur as late as 30 years after the initial treatment. Because 70% of the patients present with stage I tumors, surgery represents the most important therapeutic arm. There are no data to support any kind of postoperative adjuvant treatment for patients with stage IA or IB SCSTs, given the indolent nature of these neoplasms and the overall good prognosis. The long natural history of the disease may lead to repeated surgical procedure should a relapse occurs. Platinum-based chemotherapy is currently used for patients with advanced stage SCSTs or recurrent disease, with an overall response rate of 63% to 80%. The indolent nature of SCSTs with the tendency for late recurrence requires long-term follow-up.

Gynecologic Cancer InterGroup (GCIG) Consensus Review for Ovarian and Primary Peritoneal Low-Grade Serous Carcinomas

Abstract Low-grade serous ovarian cancer is a recently described histological subtype of ovarian cancer that is clinically and molecularly distinct from the 4 other main histological subtypes (high-grade serous, clear cell, endometrioid, and mucinous). In particular, it differs from high-grade serous ovarian cancer in that it presents at a much younger age, is more indolent, and is relatively chemoresistant. Very few clinical trials have been performed exclusively in this tumor type; and as such, specific data guiding optimal management are limited.

Gynecologic cancer intergroup (GCIG) consensus review for uterine serous carcinoma

Objectives Uterine serous carcinoma (USC) represents a rare and aggressive histologic subtype of endometrial cancer, associated with a poor prognosis. This article critically reviews the literature pertinent to the epidemiology, pathology, molecular biology, diagnosis, management, and perspectives of patients with USC. Methods As one of a series of The Gynecologic Cancer InterGroup (GCIG) Rare Tumor Working Group in London, November 2013, we discussed about USC many times with various experts among international GCIG groups. Results Both USC and approximately 25% of high-grade endometrioid tumors represent extensive copy number alterations, few DNA methylation changes, low estrogen and progesterone levels, and frequent P53mutations. Uterine serous carcinoma shares molecular characteristics with ovarian serous and basal-like breast carcinomas. In addition to optimal surgery, platinum- and taxane-based chemotherapy should be considered in the treatment of both early- and advanced-stage disease. The combination of radiation and chemotherapy appears to be associated with the highest survival rates. The role of radiation therapy in the management of this disease, with a high propensity for distant failures, remains elusive. Conclusions Uterine serous carcinoma is a unique and biologically aggressive subtype of endometrial cancer and should be studied as a distinct entity. Futures studies should identify the optimized chemotherapy and radiation regimens, sequence of therapy and schedule, and the role of targeted biologic therapy.