Amber Yasmeen

Chemical targeting of the innate antiviral response by histone deacetylase inhibitors renders refractory cancers sensitive to viral oncolysis

Intratumoral innate immunity can play a significant role in blocking the effective therapeutic spread of a number of oncolytic viruses (OVs). Histone deacetylase inhibitors (HDIs) are known to influence epigenetic modifications of chromatin and can blunt the cellular antiviral response. We reasoned that pretreatment of tumors with HDIs could enhance the replication and spread of OVs within malignancies. Here, we show that HDIs markedly enhance the spread of vesicular stomatitis virus (VSV) in a variety of cancer cells in vitro, in primary tumor tissue explants and in multiple animal models. This increased oncolytic activity correlated with a dampening of cellular IFN responses and augmentation of virus-induced apoptosis. These results illustrate the general utility of HDIs as chemical switches to regulate cellular innate antiviral responses and to provide controlled growth of therapeutic viruses within malignancies. HDIs could have a profoundly positive impact on the clinical implementation of OV therapeutics.

Induction of apoptosis by metformin in epithelial ovarian cancer: Involvement of the Bcl-2 family proteins

OBJECTIVE The aims of the study were to evaluate the ability of metformin to induce apoptosis in epithelial ovarian cancer cell lines and to identify the pathways involved in this effect. METHODS After treatment with metformin and/or cisplatin, OVCAR-3 and OVCAR-4 cellular apoptosis was assessed by flow cytometry and caspase 3/7 activity. Cell cycle analysis was also performed by flow cytometry as well. Modulation of protein expression of the Bcl-2 family after treatment with metformin and/or cisplatin was determined by Western blotting. RESULTS Metformin induced apoptosis in OVCAR-3 and OVCAR-4 cell lines in an AMPK-independent manner and provoked a cell cycle arrest in the S and G2/M phase. Moreover, we established that metformin can induce apoptosis in OVCAR-3 and OVCAR-4 cells by activating caspases 3/7, down-regulating Bcl-2 and Bcl-xL expression, and up-regulating Bax and Bad expression. The induction of apoptosis by metformin was also enhanced by cisplatin and combination of these drugs did not modulate the expression of Bcl-2 family proteins in OVCAR-3 cell line, whereas the effect was enhanced in OVCAR-4 cell line. CONCLUSION Bcl-xL and Bcl-2 targeted strategies were suggested to constitute an effective therapeutic tool for the treatment of chemoresistant ovarian carcinoma, in conjunction with conventional chemotherapy. These data are relevant to ongoing translational research efforts and clinical trials exploring a possible protective effect of metformin against ovarian cancer, including Bcl-2 inhibition.

Relevance of the OCT1 transporter to the antineoplastic effect of biguanides

Epidemiologic and laboratory data suggesting that metformin has antineoplastic activity have led to ongoing clinical trials. However, pharmacokinetic issues that may influence metformin activity have not been studied in detail. The organic cation transporter 1 (OCT1) is known to play an important role in cellular uptake of metformin in the liver. We show that siRNA knockdown of OCT1 reduced sensitivity of epithelial ovarian cancer cells to metformin, but interestingly not to another biguanide, phenformin, with respect to both activation of AMP kinase and inhibition of proliferation. We observed that there is heterogeneity between primary human tumors with respect to OCT1 expression. These results suggest that there may be settings where drug uptake limits direct action of metformin on neoplastic cells, raising the possibility that metformin may not be the optimal biguanide for clinical investigation.

E6/E7 of HPV Type 16 Promotes Cell Invasion and Metastasis of Human Breast Cancer Cells

Human papillomaviruses (HPVs) could be important risk factors for breast carcinogenesis and metastasis, as roughly 50% of breast cancers are positive for high-risk HPVs. To determine the role of high-risk HPVs in human breast carcinogenesis and metastasis, we examined the effect of E6/E7 of HPV type 16 in two non-invasive breast cancer cell lines, MCF7 and BT20. We report that E6/E7 of HPV type 16 induces cell invasive and metastatic abilities of MCF7 and BT20 in vitro and in vivo, respectively, in comparison with the wild type cells. This is accompanied by an up-regulation of Id-1, a family member of helix-loop-helix (HLH) transcription factors, in MCF7 and BT20 cell lines which express E6/E7. Earlier studies have reported that Id-1 regulates cell invasion and metastasis of human breast cancer cells. To gauge the role of Id-1 in cell invasion and metastasis induced by E6/E7 of HPV type 16, we investigated the effect of E6/E7 in mouse normal embryonic fibroblast (NEF) and knockout Id-1 (Id-1-/-) cells. We establish that E6/E7 induces cell invasive ability in NEF but not Id-1-/- cells; moreover, we were able to inhibit the invasion ability of MCF7-E6/E7 and BT20-E6/E7 using Id-1 antisense retroviruses. Furthermore, we report that E6/E7 oncoproteins up-regulate Id-1 promoter activity in MCF7 and BT20 cells. We also found that HPV type 16 is present in all invasive and metastatic breast cancer and less frequently in in-situ breast cancer as opposed to normal mammary tissue. In parallel, we demonstrate that Id-1 over-expression is correlated with the presence of HPV type 16 in human invasive and metastatic breast cancer. These data suggest that high-risk HPV infections can induce cell invasion and metastasis in breast cancer through Id-1 regulation.

Targeting Insulin and Insulin-Like Growth Factor Pathways in Epithelial Ovarian Cancer

Ovarian cancer is the most lethal of all gynecological malignancies, due in part to the diagnosis at an advanced stage caused by the lack of specific signs and symptoms and the absence of reliable tests for screening and early detection. Most patients will respond initially to treatment but about 70% of them will suffer a recurrence. Therefore, new therapeutic modalities are urgently needed to overcome chemoresistance observed in ovarian cancer patients. Evidence accumulates suggesting that the insulin/insulin growth factor (IGF) pathways could act as a good therapeutic target in several cancers, including ovarian cancer. In this paper, we will focus on the role of insulin/IGF in ovarian cancer tumorigenesis and treatment.

Identification of deregulated genes by single wall carbon-nanotubes in human normal bronchial epithelial cells

To identify genes affected by single-walled carbon nanotubes (SWCNTs) in human normal lung cells, we compared the gene expression profiles of untreated human normal bronchial epithelial (HNBE) cells to profiles of HNBE cells treated with SWCNTs. A complementary DNA microarray analysis consisting of 54,675 human genes revealed marked changes in the expression of 14,294 genes, with 7,029 genes being upregulated and 7,265 being downregulated. This comprehensive list of genes included those associated with cell cycle, apoptosis, cell survival, cell adhesion and motility, signal transduction, and transcription regulation. Additional analysis of 19 genes using reverse transcription-polymerase chain reaction confirmed the microarray analysis. More specifically, our study demonstrates to our knowledge for the first time, evidence that 9 of the 19 genes (most of which encode cell apoptotic, signal transduction, and transcription regulator products) are upregulated in the SWCNTs-treated HNBE cells as compared with untreated cells, whereas the remaining 10 of the 19 (involved in cell adhesion and motility, cell proliferation, and cell survival) are downregulated in SWCNTs-treated HNBE cells in comparison with untreated controls. These findings provide a large body of information regarding gene expression profiles associated with SWCNTs exposure in human lung bronchial epithelial cells, and also represent a source to investigate the mechanism of the effect of SWCNTs in human normal lung cells. From the clinical editor: In this study, the gene expression profile of human normal bronchial epithelial cells was compared with single-wall carbon nanotubes-treated cells. A cDNA microarray analysis consisting of 54,675 human genes revealed significant changes in the expression of 14,294 genes, with 7,029 genes being up-regulated and 7,265 being down-regulated. This serves as a first step in clarification of mechanisms of action and to investigate toxicity in this model.

ErbB receptors and epithelial-cadherin-catenin complex in human carcinomas.

The ErbB family of receptor tyrosine kinases have important roles in maintaining normal epithelial cell function. The ErbBs are involved in the interaction between cells and cell-matrix adhesion molecules and have proven critical in maintaining the integrity of the epithelial cell environment. Deregulation of these tyrosine receptors has been associated with several human diseases. In particular, the expression or activation of epidermal growth factor receptor (EGFR) and ErbB2 is altered in many epithelial tumors. Epithelial (E)-cadherin is another major molecule expressed by epithelial cells. To create efficient cell-cell adhesion, E-cadherin couples its cytoplasmic domain to catenins and the actin cytoskeleton. The loss of intercellular adhesion appears to be a fundamental aspect of the neoplastic phenomena. In addition, EGFR and ErbB2 signaling associated with the E-cadherin-catenin complex has been demonstrated in normal and cancer cells. This signaling is involved in regulating cell adhesion and the invasive growth of cancers. This article provides an overview of the interaction between the ErbB tyrosine receptors and the E-cadherin-catenin complex in human carcinomas.

Locking Src/Abl Tyrosine Kinase Activities Regulate Cell Differentiation and Invasion of Human Cervical Cancer Cells Expressing E6/E7 Oncoproteins of High-Risk HPV.

In this study, we compared the effects of SKI-606 with Iressa, Src/Abl and EGF-R kinase inhibitors, respectively, on selected parameters in HeLa and SiHa cervical cancer cell lines, which express E6/E7 oncoproteins of high-risk HPV types 18 and 16, respectively. Our results show that SKI-606 and Iressa inhibit cell proliferation and provoke G0-G1 cell cycle arrest and reduction of S and G2-M phase using 2 and 5 μM concentrations of these inhibitors. In contrast, SKI-606 induces differentiation to an epithelial phenotype “mesenchymal-epithelial transition”; thus SKI-606 causes a dramatic decrease in cell motility and invasion abilities of HeLa and SiHa cancer cells, in comparison to untreated cells and Iressa-treated cells in which these parameters are only slightly affected. These changes are accompanied by a regulation of the expression patterns of E-cadherin and catenins. The molecular pathway analysis of Src/Abl inhibitor revealed that SKI-606 blocks the phosphorylation of β-catenin and consequently converts its role from a transcriptional regulator to a cell-cell adhesion molecule. Our findings indicate that SKI-606 inhibits signaling pathways involved in regulating tumor cell migration and invasion genes via β-catenin alteration, suggesting that Src inhibitor, in comparison to EGF-R, is a promising therapeutic agent for human cervical cancer.

BMS-536924 sensitizes human epithelial ovarian cancer cells to the PARP inhibitor, 3-aminobenzamide

OBJECTIVE To evaluate the anti-neoplastic activity of BMS-536924, an IGF-1R inhibitor, in epithelial ovarian cancer and its capacity to potentiate the effect of a PARP inhibitor, 3-aminobenzamide. METHODS OVCAR-3, OVCAR-4, SKOV-3 and TOV-81D cell lines were investigated in low-serum tissue culture conditions (1%FBS). Cytotoxicity assays were performed in quadruplicates using the Alamar colorimetric assay in the presence of BMS-536924 and/or 3-aminobenzamide. The levels of phospho-AKT, phospho-S6, PARP-1 and phospho-H2AX were evaluated by western blotting in the presence of BMS-536924. RESULTS BMS-536924 induced a time and dose inhibitory effect on cell survival. This effect seemed to be mediated by a reduction of pAKT and pS6 in a dose-dependent manner. The drug also provoked cell death by apoptosis as suggested by the increase in PARP-1 cleavage. It also induces DNA damage as demonstrated by the increased phosphorylation of histone H2AX and the augmentation of the comet tail moment. Finally, BMS-536924 sensitized cells to the effect of the PARP inhibitor, 3-aminobenzamide. CONCLUSION Our study reinforces the concept that IGF-1R is a good therapeutic target in ovarian cancer. Moreover, it suggests that combination therapy using BMS-536924 with a PARP inhibitor might be an effective strategy to circumvent resistance to treatment in clinical settings.

High-Risk HPV/ErbB-2 Interaction on E-Cadherin/Catenin Regulation in Human Carcinogenesis

Human papillomaviruses (HPVs) are a group of host-specific DNA viruses, with more than 120 different types identified to date. HPVs are classified as high- or low-risk (HR or LR) depending on their potential to induce cancer. Persistent infections with HR types of HPVs present a major risk factor for the development of a variety of human cancers including cervical, colorectal, head and neck as well as breast cancers. On the other hand, the deregulation of ErbB family tyrosine kinase receptors has also been associated with several types of human cancers. For instance, ErbB2 has been shown to have an important role in human carcinomas, specifically breast cancer. Moreover, the E-cadherin/catenin complex plays a pivotal role in the maintenance of normal adhesion in epithelial cells, and has been demonstrated to suppress tumor invasion and participate in cell signaling in human carcinomas. This review focuses on the interaction between HR-HPV/ErbB2 tyrosine receptors and the E-cadherin/catenin complex in human carcinomas including cervical, colorectal, head and neck and breast cancers.