Aamer Qazi

Ritonavir blocks AKT signaling, activates apoptosis and inhibits migration and invasion in ovarian cancer cells

BackgroundOvarian cancer is the leading cause of mortality from gynecological malignancies, often undetectable in early stages. The difficulty of detecting the disease in its early stages and the propensity of ovarian cancer cells to develop resistance to known chemotherapeutic treatments dramatically decreases the 5-year survival rate. Chemotherapy with paclitaxel after surgery increases median survival only by 2 to 3 years in stage IV disease highlights the need for more effective drugs. The human immunodeficiency virus (HIV) infection is characterized by increased risk of several solid tumors due to its inherent nature of weakening of immune system. Recent observations point to a lower incidence of some cancers in patients treated with protease inhibitor (PI) cocktail treatment known as HAART (Highly Active Anti-Retroviral Therapy).ResultsHere we show that ritonavir, a HIV protease inhibitor effectively induced cell cycle arrest and apoptosis in ovarian cell lines MDH-2774 and SKOV-3 in a dose dependent manner. Over a 3 day period with 20 μM ritonavir resulted in the cell death of over 60% for MDAH-2774 compared with 55% in case of SKOV-3 cell line. Ritonavir caused G1 cell cycle arrest of the ovarian cancer cells, mediated by down modulating levels of RB phosphorylation and depleting the G1 cyclins, cyclin-dependent kinase and increasing their inhibitors as determined by gene profile analysis. Interestingly, the treatment of ritonavir decreased the amount of phosphorylated AKT in a dose-dependent manner. Furthermore, inhibition of AKT by specific siRNA synergistically increased the efficacy of the ritonavir-induced apoptosis. These results indicate that the addition of the AKT inhibitor may increase the therapeutic efficacy of ritonavir.ConclusionOur results demonstrate a potential use of ritonavir for ovarian cancer with additive effects in conjunction with conventional chemotherapeutic regimens. Since ritonavir is clinically approved for human use for HIV, drug repositioning for ovarian cancer could accelerate the process of traditional drug development. This would reduce risks, limit the costs and decrease the time needed to bring the drug from bench to bedside.

Sulforaphane induces cell cycle arrest by protecting RB-E2F-1 complex in epithelial ovarian cancer cells

BackgroundSulforaphane (SFN), an isothiocyanate phytochemical present predominantly in cruciferous vegetables such as brussels sprout and broccoli, is considered a promising chemo-preventive agent against cancer. In-vitro exposure to SFN appears to result in the induction of apoptosis and cell-cycle arrest in a variety of tumor types. However, the molecular mechanisms leading to the inhibition of cell cycle progression by SFN are poorly understood in epithelial ovarian cancer cells (EOC). The aim of this study is to understand the signaling mechanisms through which SFN influences the cell growth and proliferation in EOC.ResultsSFN at concentrations of 5 - 20 μM induced a dose-dependent suppression of growth in cell lines MDAH 2774 and SkOV-3 with an IC50 of ~8 μM after a 3 day exposure. Combination treatment with chemotherapeutic agent, paclitaxel, resulted in additive growth suppression. SFN at ~8 μM decreased growth by 40% and 20% on day 1 in MDAH 2774 and SkOV-3, respectively. Cells treated with cytotoxic concentrations of SFN have reduced cell migration and increased apoptotic cell death via an increase in Bak/Bcl-2 ratio and cleavage of procaspase-9 and poly (ADP-ribose)-polymerase (PARP). Gene expression profile analysis of cell cycle regulated proteins demonstrated increased levels of tumor suppressor retinoblastoma protein (RB) and decreased levels of E2F-1 transcription factor. SFN treatment resulted in G1 cell cycle arrest through down modulation of RB phosphorylation and by protecting the RB-E2F-1 complex.ConclusionsSFN induces growth arrest and apoptosis in EOC cells. Inhibition of retinoblastoma (RB) phosphorylation and reduction in levels of free E2F-1 appear to play an important role in EOC growth arrest.

MicroRNA-101 Inhibits Growth of Epithelial Ovarian Cancer by Relieving Chromatin-Mediated Transcriptional Repression of p21 waf1/cip1

ABSTRACTPurposeMicroRNA-101 (miR-101) expression is negatively associated with tumor growth and proliferation in several solid epithelial cancers. Enhancer of zeste homolog 2 (EzH2) appears to be a functional target of miR-101. We explore the role of miR-101 and its interaction with EzH2 in epithelial ovarian carcinoma (EOC).MethodsIn situ hybridization (ISH) for miR-101 was performed on EOC patient tissues and normal controls. EOC cell lines were transfected with miR-101 and subjected to growth analysis and clonogenic assays. Cell motility was assessed by Boyden chamber and wound-healing assays. P21waf1/cip1 and EzH2 interaction was assessed by Chromatin Immunoprecipitation (ChIP) assay in MDAH-2774 cells. SCID mice were assessed for tumor burden after injection with miR-101 or control vector-treated MDAH-2774 cells.ResultsISH analysis revealed a decrease in miR-101 expression in EOC compared with normal tissue. MiR-101 re-expression in EOC cell lines resulted in increased apoptosis, decreased cellular proliferation, invasiveness, and reduced growth of tumor xenografts. CHIP assays revealed that re-expression of miR-101 inhibited the interaction of EzH2 with p21waf1/cip1 promoter.ConclusionsMiR-101 re-expression appears to have antitumor effects, providing a better understanding of the role of miR-101 in EOC.

Telomere maintenance in laser capture microdissection-purified Barrett's adenocarcinoma cells and effect of telomerase inhibition in vivo.

Purpose: The aims of this study were to investigate telomere function in normal and Barretts esophageal adenocarcinoma (BEAC) cells purified by laser capture microdissection and to evaluate the effect of telomerase inhibition in cancer cells in vitro and in vivo. Experimental Design: Epithelial cells were purified from surgically resected esophagi. Telomerase activity was measured by modified telomeric repeat amplification protocol and telomere length was determined by real-time PCR assay. To evaluate the effect of telomerase inhibition, adenocarcinoma cell lines were continuously treated with a specific telomerase inhibitor (GRN163L) and live cell number was determined weekly. Apoptosis was evaluated by Annexin labeling and senescence by β-galactosidase staining. For in vivo studies, severe combined immunodeficient mice were s.c. inoculated with adenocarcinoma cells and following appearance of palpable tumors, injected i.p. with saline or GRN163L. Results: Telomerase activity was significantly elevated whereas telomeres were shorter in BEAC cells relative to normal esophageal epithelial cells. The treatment of adenocarcinoma cells with telomerase inhibitor, GRN163L, led to loss of telomerase activity, reduction in telomere length, and growth arrest through induction of both the senescence and apoptosis. GRN163L-induced cell death could also be expedited by addition of the chemotherapeutic agents doxorubicin and ritonavir. Finally, the treatment with GRN163L led to a significant reduction in tumor volume in a subcutaneous tumor model. Conclusions: We show that telomerase activity is significantly elevated whereas telomeres are shorter in BEAC and suppression of telomerase inhibits proliferation of adenocarcinoma cells both in vitro and in vivo.

Genomic evolution in Barrett's adenocarcinoma cells: Critical roles of elevated hsRAD51, homologous recombination and Alu sequences in the genome

A prominent feature of most cancers including Barretts adenocarcinoma (BAC) is genetic instability, which is associated with development and progression of disease. In this study, we investigated the role of recombinase (hsRAD51), a key component of homologous recombination (HR)/repair, in evolving genomic changes and growth of BAC cells. We show that the expression of RAD51 is elevated in BAC cell lines and tissue specimens, relative to normal cells. HR activity is also elevated and significantly correlates with RAD51 expression in BAC cells. The suppression of RAD51 expression, by short hairpin RNA (shRNA) specifically targeting this gene, significantly prevented BAC cells from acquiring genomic changes to either copy number or heterozygosity (P<0.02) in several independent experiments employing single-nucleotide polymorphism arrays. The reduction in copy-number changes, following shRNA treatment, was confirmed by Comparative Genome Hybridization analyses of the same DNA samples. Moreover, the chromosomal distributions of mutations correlated strongly with frequencies and locations of Alu interspersed repetitive elements on individual chromosomes. We conclude that the hsRAD51 protein level is systematically elevated in BAC, contributes significantly to genomic evolution during serial propagation of these cells and correlates with disease progression. Alu sequences may serve as substrates for elevated HR during cell proliferation in vitro, as they have been reported to do during the evolution of species, and thus may provide additional targets for prevention or treatment of this disease.

Expression of GLUT-1 in epithelial ovarian carcinoma: Correlation with tumor cell proliferation, angiogenesis, survival and ability to predict optimal cytoreduction

OBJECTIVE GLUT-1 is involved at various steps in the processes of tumor progression. The objective of this study was to examine the relationship between GLUT-1 expression and tumor proliferation and angiogenesis in epithelial ovarian carcinoma. MATERIALS AND METHODS Specimens from 213 patients with epithelial ovarian carcinoma were evaluated by immunohistochemistry for GLUT-1, Ki-67, and vascular endothelial growth factor. Tumor microvessel density was assessed with CD34 immunostaining. We investigated the relationships between GLUT-1 expression and clinicopathologic characteristics, tumor angiogenesis (tumor MVD and vascular endothelial growth factor expression), and tumor proliferation (Ki-67). The effect of GLUT-1 expression on patient survival and on the volume of residual disease after cytoreduction was determined. RESULTS There was a significant positive correlation between expression of GLUT-1, Ki-67, and microvessel density. In univariate survival analysis, high GLUT-1 expression, high Ki-67 expression and high tumor microvessel density showed a significant impact on patient survival (p=0.0001). In multivariate analysis including patients with all tumor stages, after controlling for age, race, stage, grade, MVD, and the 3 markers (GLUT-1, Ki-67 and VEGF), only age (HR 1.5; 95% CI 1-2.3), stage (HR 3.6; 95% CI 1.8-7.5) and grade (HR 2.3; 95% CI 1.2-4.5) retained their significance as independent poor prognostic factors. Tumors simultaneously overexpressing GLUT-1 and Ki-67 were less likely to be optimally cytoreduced as compared to tumors overexpressing only one or neither of those two markers (OR: 3.8, p=0.01). CONCLUSION Expression of GLUT-1 correlates with tumor proliferation and microvessel density in epithelial ovarian carcinoma. In addition, patients with rapidly proliferating advanced stage tumors overexpressing GLUT-1 have a lesser chance for optimal cytoreduction.

EZH2 blockade by RNA interference inhibits growth of ovarian cancer by facilitating re-expression of p21waf1/cip1 and by inhibiting mutant p53

The enhancer of zeste homolog 2 (EZH2) methyltransferase is a transcriptional repressor. EZH2 is abnormally elevated in epithelial ovarian cancer (EOC). We demonstrated that EZH2 knockdown inhibited cell growth, activated apoptosis, and enhanced chemosensitivity. Further, silencing of EZH2 resulted in re-expression of p21(waf1/cip1) and down-regulation of mutant p53. Finally, EZH2 knockdown contributed to attenuated EOC growth in SCID mice.

Restoration of E-cadherin expression in pancreatic ductal adenocarcinoma treated with microRNA-101.

PURPOSE To investigate the possibility of inhibiting the progression of pancreatic ductal adenocarcinoma (PDAC) by facilitating the expression of E-cadherin through the enforced expression of microRNA-101 (miR-101). METHODS In situ hybridization was conducted with archival tissue using a double digoxigenin-labeled probe. Chromatin immunoprecipitation (ChIP) assay was conducted with EZ-Magna ChIPTM A. Gene profile analysis, Western blot, and immunoprecipitation assays were performed using standard protocols. RESULTS We found that decreased miR-101 expression observed in archival patient tissues was significantly associated with poor prognosis indicated by low-intensity staining in high-grade tumors. ChIP assays using anti-enhancer of zeste homolog 2 (EZH2) antibodies indicated not only the interaction of EZH2 to the CDH1 (E-cadherin) promoter, but also that this interaction was significantly diminished in cells transfected with pre-miR-101. We observed a global downregulation of trimethylated lysine 27 of H3 histone (H3K27me3) along with upregulation of the enzymes histone deacetylase -1 and -2 with the re-expression of miR-101. Further, we observed lesser levels of transcriptional factors that inhibit the CDH1 promoter with pre-miR-101 treatment. Western blot analysis confirmed the enhanced E-cadherin expression. PANC-1 cells transduced with pre-miR-101 displayed markedly attenuated growth in SCID mice. CONCLUSION These results suggest the potential therapeutic use of miR-101-enforced expression for inhibition of PDAC.

Prognosis and reproducibility of new and existing binary grading systems for endometrial carcinoma compared to FIGO grading in hysterectomy specimens.

Background: The current International Federation of Gynecology and Obstetrics (FIGO) grade in endometrial carcinomas requires the evaluation of histologic features with proven prognostic value but with questionable reproducibility. This study tests the prognostic power and reproducibility of a new binary grading system. Study Design: Specimens from 254 hysterectomies were graded according to the new 3- and 2-tiered FIGO grading systems described by Alkushi et al. The selected morphologic parameters for the new grading system included the presence of predominant solid or papillary architecture pattern, severe nuclear atypia, tumor necrosis, and vascular invasion. The Cox proportional hazards and κ statistics were used for comparisons. Results: On multivariate analysis, and looking at all tumor cell types, the 4 tested grading systems were independent predictors of survival, with the 3-tiered FIGO grading system being the most predictive (P = 0.005). In the subset of endometrioid tumors, the 3- and 2-tiered FIGO grading systems and the new grading system retained their statistical significance as predictors of survival (P = 0.004, P = 0.03, and P = 0.007, respectively), whereas the grading system of Alkushi et al did not (P = 0.1). In nonendometrioid tumors, the new grading system proved to be the best predictor of survival, reaching near statistical significance (P = 0.06). The new grading system had acceptable intraobserver and interobserver reproducibility assessment (κ = 0.87 and κ = 0.45, respectively). Conclusion: The 3-tiered FIGO grading system retained its superior prognostic power. However, available binary grading systems remain an attractive option by being highly reproducible and by eliminating the clinical ambiguity of intermediate grades of disease.

Enhanced phosphorylation of p53 by microRNA-26a leading to growth inhibition of pancreatic cancer.

PURPOSE MicroRNA (miR)-26a has been identified as a tumor suppressor in pancreatic cancer cells. Although wild-type p53 controls cell-cycle progression, its mutant form normally present in pancreatic cancer loses this capability. Phosphorylation is known to restore wild-type activity to mutant p53. We, therefore, examined whether miR-26a treatment can restore wild-type functions of mutant p53 via phosphorylation, resulting in inhibition of cell growth. METHODS The human pancreatic cancer cell line BxPc-3 harboring mutant p53 was used for colony formation, cell-cycle, and Western blotting assays. Gene profile analysis was conducted after transfection with pre-miR-26a. RESULTS miR-26a expression significantly decreased cell proliferation by 80% along with marked inhibition of colony formation and cell migration. Cell-cycle inhibition at the G0/G1 interface was observed along with enhanced drug retention and increased chemosensitivity to gemcitabine. Mutant p53 was phosphorylated rapidly at its Ser9 and Ser392 residues, but not at Ser15 or Ser20. Gene profile analysis of pre-miR-26a-transfected cells showed a significant increase in gene transcripts promoting apoptosis and p53 activation, with decreased levels of genes involved in cell-cycle progression. CONCLUSION Delivery of miR-26a may represent a novel strategy for inhibiting pancreatic cancer growth, at least in part by enhancing phosphorylation of mutant p53 to restore its wild-type functions.