Roland Matthews

Prohibitin silencing reverses stabilization of mitochondrial integrity and chemoresistance in ovarian cancer cells by increasing their sensitivity to apoptosis

Current approaches to the treatment of ovarian cancer are limited because of the development of resistance to chemotherapy. Prohibitin (Phb1) is a possible candidate protein that contributes to development of drug resistance, which could be targeted in neoplastic cells. Phb1 is a highly conserved protein that is associated with a block in the G0/G1 phase of the cell cycle and also with cell survival. Our study was designed to determine the role of Phb1 in regulating cellular growth and apoptosis in ovarian cancer cells. Our results showed that Phb1 content is differentially overexpressed in papillary serous ovarian carcinoma and endometrioid ovarian adenocarcinoma when compared to normal ovarian epithelium and was inversely related to Ki67 expression. Immunofluorescence microscopy and Western analyses revealed that Phb1 is primarily associated with the mitochondria in ovarian cancer cells. Over‐expression of Phb1 by adenoviral Phb1 infection resulted in an increase in the percentage of ovarian cancer cells accumulating at G0/G1 phase of the cell cycle. Treatment of ovarian cancer cells with staurosporine (STS) induced apoptosis in a time‐dependent manner. Phb1 over‐expression induced cellular resistance to STS via the intrinsic apoptotic pathway. In contrast, silencing of Phb1 expression by adenoviral small interfering RNA (siRNA) sensitized ovarian cancer cells to STS‐induce apoptosis. Taken together, these results suggest that Phb1 induces block at G0/G1 phase of the cell cycle and promotes survival of cancer cells. Furthermore, silencing of the Phb1 gene expression may prove to be a valuable therapeutic approach for chemoresistant ovarian cancer by increasing sensitivity of cancer cells to apoptosis.

Mitochondrial Dysfunction and Adipogenic Reduction by Prohibitin Silencing in 3T3-L1 Cells

Increase in mitochondrial biogenesis has been shown to accompany brown and white adipose cell differentiation. Prohibitins (PHBs), comprised of two evolutionarily conserved proteins, prohibitin-1 (PHB1) and prohibitin-2 (PHB2), are present in a high molecular-weight complex in the inner membrane of mitochondria. However, little is known about the effect of mitochondrial PHBs in adipogenesis. In the present study, we demonstrate that the levels of both PHB1 and PHB2 are significantly increased during adipogenesis of 3T3-L1 preadipocytes, especially in mitochondria. Knockdown of PHB1 or PHB2 by oligonucleotide siRNA significantly reduced the expression of adipogenic markers, the accumulation of lipids and the phosphorylation of extracellular signal-regulated kinases. In addition, fragmentation of mitochondrial reticulum, loss of mitochondrial cristae, reduction of mitochondrial content, impairment of mitochondrial complex I activity and excessive production of ROS were observed upon PHB-silencing in 3T3-L1 cells. Our results suggest that PHBs are critical mediators in promoting 3T3-L1 adipocyte differentiation and may be the potential targets for obesity therapies.

Prohibitin (PHB) acts as a potent survival factor against ceramide induced apoptosis in rat granulosa cells

AIM Ceramide is a key factor in inducing germ cell apoptosis by translocating from cumulus cells into the adjacent oocyte and lipid rafts through gap junctions. Therefore studies designed to elucidate the mechanistic pathways in ceramide induced granulosa cell (GC) apoptosis and follicular atresia may potentially lead to the development of novel lipid-based therapeutic strategies that will prevent infertility and premature menopause associated with chemo and/or radiation therapy in female cancer patients. Our previous studies have shown that Prohibitin (PHB) is intimately involved in GCs differentiation, atresia, and luteolysis. MAIN METHODS In the present study, we have examined the functional effects of loss-/gain-of-function of PHB using adenoviral technology in delaying apoptosis induced by the physiological ligand ceramide in rat GCs. KEY FINDINGS Under these experimental conditions, exogenous ceramide C-8 (50 μM) augmented the expression of mitochondrial PHB and subsequently cause the physical destruction of GC by the release of mitochondrial cytochrome c and activation of caspase-3. In further studies, silencing of PHB expression by adenoviral small interfering RNA (shRNA) sensitized GCs to ceramide C8-induce apoptosis. In contrast, adenovirus (Ad) directed overexpression of PHB in GCs resulted in increased PHB content in mitochondria and delayed the onset of ceramide induced apoptosis in the infected GCs. SIGNIFICANCE Taken together, these results provide novel evidences that a critical level of PHB expression within the mitochondria plays a key intra-molecular role in GC fate by mediating the inhibition of apoptosis and may therefore, contribute significantly to ceramide induced follicular atresia.

The emerging roles of prohibitins in folliculogenesis.

Prohibitins are members of a highly conserved eukaryotic protein family containing the stomatin/prohibitin/flotillin/HflK/C (SPFH) domain (also known as the prohibitin (PHB) domain) found in divergent species from prokaryotes to eukaryotes. Prohibitins are found in unicellular eukaryotes, fungi, plants, animals and humans. Prohibitins are ubiquitously expressed and present in multiple cellular compartments including the mitochondria, nucleus, and the plasma membrane, and shuttles between the mitochondria, cytosol and nucleus. Multiple functions have been attributed to the mitochondrial and nuclear prohibitins, including cellular differentiation, anti-proliferation, and morphogenesis. In the present review, we focus on the recent developments in prohibitins research related to folliculogenesis. Based on current research findings, the data suggest that these molecules play important roles in modulating specific responses of granulose cells to follicle stimulating hormone (FSH) by acting at multiple levels of the FSH signal transduction pathway. Understanding the molecular mechanisms by which the intracellular signaling pathways utilize prohibitins in governing folliculogenesis is likely to result in development of strategies to overcome fertility disorders and suppress ovarian cancer growth.

Assessing needs and assets for building a regional network infrastructure to reduce cancer related health disparities

Significant cancer health disparities exist in the United States and Puerto Rico. While numerous initiatives have been implemented to reduce cancer disparities, regional coordination of these efforts between institutions is often limited. To address cancer health disparities nation-wide, a series of regional transdisciplinary networks through the Geographic Management Program (GMaP) and the Minority Biospecimen/Biobanking Geographic Management Program (BMaP) were established in six regions across the country. This paper describes the development of the Region 3 GMaP/BMaP network composed of over 100 investigators from nine institutions in five Southeastern states and Puerto Rico to develop a state-of-the-art network for cancer health disparities research and training. We describe a series of partnership activities that led to the formation of the infrastructure for this network, recount the participatory processes utilized to develop and implement a needs and assets assessment and implementation plan, and describe our approach to data collection. Completion, by all nine institutions, of the needs and assets assessment resulted in several beneficial outcomes for Region 3 GMaP/BMaP. This network entails ongoing commitment from the institutions and institutional leaders, continuous participatory and engagement activities, and effective coordination and communication centered on team science goals.

Georgia Primary Care Providers’ Knowledge of Hereditary Breast and Ovarian Cancer Syndrome

Hereditary breast and ovarian cancer syndrome (HBOC) is an inherited condition associated with mutations in the BRCA1 or BRCA2 (BRCA) genes. Identification of individuals with HBOC requires that primary care providers understand the genetic principles required to appropriately collect family history and refer individuals for genetic evaluation. A survey was developed and administered to primary care providers in Georgia to assess their existing knowledge of HBOC and direct targeted educational efforts.We found that Georgia providers demonstrate some knowledge of basic genetic principles but were unable to consistently identify individuals at risk for HBOC. Knowledge deficits included lack of understanding of inheritance patterns and failure to recognize the significance of ovarian cancer history. Strategies for improving identification of patients with HBOC include increasing provider knowledge and integrating HBOC risk assessment tools into practice. Identification of individuals at risk is the critical first step in the process of reducing incidence of breast and ovarian cancer associated with BRCA mutations.

An examination of racial differences in 5‐year survival of cervical cancer among African American and white American women in the southeastern US from 1985 to 2010

Disparities in Cervical Cancer (CC) mortality outcomes between African American (AA) and White women have been studied for decades. However, conclusions about the effect of race on CC survival differ across studies. This study assessed differences in CC survival between AA and White women diagnosed between 1985 and 2010 and treated at two major hospitals in the southeastern US. The study sample included 925 AA and 1192 White women diagnosed with cervical adenocarcinoma, adenosquamous cell carcinoma, or squamous cell carcinoma. Propensity score adjustment and matching were employed to compare 5‐year survival between the two racial groups. Crude comparisons suggested relevant racial differences in survival. However, the racial differences became of small magnitude after propensity‐score adjustment and in matched analyses. Nonlinear models identified age at diagnosis, cancer stage, mode of treatment, and histological subtype as the most salient characteristics predicting 5‐year survival of CC, yet these characteristics were also associated with race. Crude racial differences in survival might be partly explained by underlying differences in the characteristics of racial groups, such as age at diagnosis, histological subtype, cancer stage, and the mode of treatment. The study results highlight the need to improve access to early screening and treatment opportunities for AA women to improve posttreatment survival from CC.

Accuracy of urinary human papillomavirus testing for the presence of cervical human papillomaviruses and higher grades of cervical intraepithelial neoplasia

Although urine‐based testing for human papillomavirus (HPV) is being explored as a practical approach for cervical cancer screening, whether the results differ by age, race, or indicators of excess body weight or in populations exposed to HPV vaccines has not been documented by previous studies. The purpose of this study was to determine the accuracy of urinary HPV testing for the presence of cervical HPVs and high‐grade cervical intraepithelial lesions (grade 2 and 3 cervical intraepithelial neoplasia [CIN]) by the aforementioned population characteristics.

Endometrial carcinoma with ectopic human chorionic gonadotropin expression

Highlights • Aggressive course and treatment resistance characterize ectopic human chorionic gonadotropin.• Recurrence of endometrial cancer with ectopic hCG was treated with brachytherapy and EMACO.• The serum hCG level can serve as a marker in tumors with ectopic hCG expression.

A higher degree of expression of DNA methyl transferase 1 in cervical cancer is associated with poor survival outcome

Background Even though novel therapies based on aberrant DNA methylation could be of particular importance for the treatment of cervical cancer (CC) because the oncoproteins E6/E7 of high-risk human papillomaviruses, the causative agents for developing CC, have the capacity to bind and upregulate DNA methyltransferases (DNMTs), to our knowledge, no previous studies have evaluated the expression of this enzyme in CC in relation to survival outcomes. The purpose of the study was to evaluate the expression of DNMT1 in CC and its association with survival outcomes. Methods The study population consisted of 76 women treated for primary CC and followed up by the University of Alabama at Birmingham (UAB) cancer registry. The expression of DNMT1 was examined using immunohistochemistry, and the degree of expression of DNMT1 was expressed as a percentage of cells positive for DNMT1 and its intensity. Cox proportional hazards model was used to assess the relationship between the degree of expression of DNMT1 and overall survival after adjusting for relevant covariates. Results The expression of DNMT1 was significantly higher in CC cells compared to that in the normal cervical epithelium. A higher percentage of cells positive for DNMT1 and a higher intensity score for DNMT1 were significantly associated with poor survival outcome (hazard ratio [HR] =4.3, P=0.03 and HR =4.9, P=0.02, respectively). Conclusion Our findings suggested that the degree of expression of DNMT1 could be considered as a target in the epigenetic treatment of CC. Replication of our results in other study populations with CC could create the opportunity of using DNMT inhibitors to treat CC.