Yadav, Vinod Kumar

Abstract Tumor metastasis refers to spread of a tumor from site of its origin to distant organs and causes majority of cancer deaths. Although >30 metastasis suppressor genes (MSGs) that negatively regulate metastasis have been identified so far, two issues are poorly understood: first, which MSGs oppose metastasis in a tumor type, and second, which molecular function of MSG controls metastasis. Herein, integrative analyses of tumor-transcriptomes (n = 382), survival data (n = 530) and lymph node metastases (n = 100) in lung cancer patients identified non-metastatic 2 (NME2) as a key MSG from a pool of >30 metastasis suppressors. Subsequently, we generated a promoter-wide binding map for NME2 using chromatin immunoprecipitation with promoter microarrays (ChIP-chip), and transcriptome profiling. We discovered novel targets of NME2 which are involved in focal adhesion signaling. Importantly, we detected binding of NME2 in promoter of focal adhesion factor, vinculin. Reduced expression of NME2 led to enhanced transcription of vinculin. In comparison, NME1, a close homolog of NME2, did not bind to vinculin promoter nor regulate its expression. In line, enhanced metastasis of NME2-depleted lung cancer cells was found in zebrafish and nude mice tumor models. The metastatic potential of NME2-depleted cells was remarkably diminished upon selective RNA-i-mediated silencing of vinculin. Together, we demonstrate that reduced NME2 levels lead to transcriptional de-repression of vinculin and regulate lung cancer metastasis.

Abstract Endoglin, a 180-kDa disulfide-linked homodimeric transmembrane receptor protein mostly expressed in tumor-associated endothelial cells, is an endogenous binding partner of GAIP-interacting protein, C terminus (GIPC). Endoglin functions as a coreceptor of TβRII that binds TGFβ and is important for vascular development, and consequently has become a compelling target for antiangiogenic therapies. A few recent studies in gastrointestinal stromal tumor (GIST), breast cancer, and ovarian cancer, however, suggest that endoglin is upregulated in tumor cells and is associated with poor prognosis. These findings indicate a broader role of endoglin in tumor biology, beyond angiogenic effects. The goal of our current study is to evaluate the effects of targeting endoglin in pancreatic cancer both in vitro and in vivo. We analyzed the antiproliferative effect of both RNAi-based and peptide ligand-based inhibition of endoglin in pancreatic cancer cell lines, the latter yielding a GIPC PDZ domain-targeting lipopeptide with notable antiproliferative activity. We further demonstrated that endoglin inhibition induced a differentiation phenotype in the pancreatic cancer cells and sensitized them against conventional chemotherapeutic drug gemcitabine. Most importantly, we have demonstrated the antitumor effect of both RNAi-based and competitive inhibitor–based blocking of endoglin in pancreatic cancer xenograft models in vivo. To our knowledge, this is the first report exploring the effect of targeting endoglin in pancreatic cancer cells. Mol Cancer Ther; 13(10); 2264–75. ©2014 AACR.

Abstract Previous studies have analyzed patterns of transcription, transcription factor (TF) binding or mapped nucleosome occupancy across the genome. These suggest that the three aspects are genetically connected but the cause and effect relationships are still unknown. For example, physiologic TF binding studies involve many TFs, consequently, it is difficult to assign nucleosome reorganization to the binding site occupancy of any particular TF. Therefore, several aspects remain unclear: does TF binding influence nucleosome (re)organizations locally or impact the chromatin landscape at a more global level; are all or only a fraction of TF binding a result of reorganization in nucleosome occupancy and do all TF binding and associated changes in nucleosome occupancy result in altered gene expression? With these in mind, following characterization of two states (before and after induction of a single TF of choice) we determined: (i) genomic binding sites of the TF, (ii) promoter nucleosome occupancy and (iii) transcriptome profiles. Results demonstrated that promoter-proximal TF binding influenced expression of the target gene when it was coupled to nucleosome repositioning at or close to its binding site in most cases. In contrast, only in few cases change in target gene expression was found when TF binding occurred without local nucleosome reorganization.