Shashikiran Donthamsetty

UNLABELLED: Following liver regeneration after partial hepatectomy, liver grows back precisely to its original mass and does not exceed it. The mechanism regulating this "hepatostat" is not clear and no exceptions have been found to date. Although pathways initiating liver regeneration have been well studied, mechanisms involved in the termination of liver regeneration are unclear. Here, we report that integrin-linked kinase (ILK) (involved in transmission of the extracellular matrix [ECM] signaling by way of integrin receptors) and/or hepatic adaptations that ensue following ILK hepatocyte-targeted removal are critical for proper termination of liver regeneration. Following partial hepatectomy (PHx), mice with a liver-specific ILK ablation (ILK-KO-Liver) demonstrate a termination defect resulting in 58% larger liver than their original pre-PHx mass. This increase in post-PHx liver mass is due to sustained cell proliferation driven in part by increased signaling through hepatocyte growth factor (HGF), and the beta-catenin pathway and Hippo kinase pathways. CONCLUSION: The data indicate that ECM-mediated signaling by way of ILK is essential in proper termination of liver regeneration. This is the first evidence of a defect leading to impaired termination of regeneration and excessive accumulation of liver weight following partial hepatectomy.

// Vaishali Pannu 1 , Padmashree C.G. Rida 1 , Angela Ogden 1 , Ravi Chakra Turaga 1 , Shashikiran Donthamsetty 1 , Nathan J. Bowen 2 , Katie Rudd 3 , Meenakshi V. Gupta 4 , Michelle D. Reid 5 , Guilherme Cantuaria 6 , Claire E. Walczak 7 and Ritu Aneja 1 1 Department of Biology, Georgia State University, Atlanta, GA, USA 2 Center for Cancer Research and Therapeutic Development, Clark Atlanta University, Atlanta, GA, USA 3 Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA 4 Clinical Pathology & Anatomic Pathology, West Georgia Hospitals, LaGrange, GA, USA 5 Department of Pathology, Emory University School of Medicine, Atlanta, GA, USA 6 Department of Gynecologic Oncology, Northside Hospital Cancer Institute, Atlanta, GA, USA 7 Department of Medical Sciences, Indiana University, Bloomington, IN, USA Correspondence to: Ritu Aneja, email: // Keywords : HSET, centrosome clustering, microtubule motor, cell-cycle kinetics, tumor progression Received : December 22, 2014 Accepted : January 20, 2015 Published : February 28, 2015 Abstract Human breast tumors harbor supernumerary centrosomes in almost 80% of tumor cells. Although amplified centrosomes compromise cell viability via multipolar spindles resulting in death-inducing aneuploidy, cancer cells tend to cluster extra centrosomes during mitosis. As a result cancer cells display bipolar spindle phenotypes to maintain a tolerable level of aneuploidy, an edge to their survival. HSET/KifC1, a kinesin-like minus-end directed microtubule motor has recently found fame as a crucial centrosome clustering molecule. Here we show that HSET promotes tumor progression via mechanisms independent of centrosome clustering. We found that HSET is overexpressed in breast carcinomas wherein nuclear HSET accumulation correlated with histological grade and predicted poor progression-free and overall survival. In addition, deregulated HSET protein expression was associated with gene amplification and/or translocation. Our data provide compelling evidence that HSET overexpression is pro-proliferative, promotes clonogenic-survival and enhances cell-cycle kinetics through G2 and M-phases. Importantly, HSET co-immunoprecipitates with survivin, and its overexpression protects survivin from proteasome-mediated degradation, resulting in its increased steady-state levels. We provide the first evidence of centrosome clustering-independent activities of HSET that fuel tumor progression and firmly establish that HSET can serve both as a potential prognostic biomarker and as a valuable cancer-selective therapeutic target.

// Vaishali Pannu 1 , Karuna Mittal 1 , Guilherme Cantuaria 2 , Michelle D. Reid 3 , Xiaoxian Li 3 , Shashikiran Donthamsetty 1 , Michelle McBride 1 , Sergey Klimov 1 , Remus Osan 4, 5 , Meenakshi V. Gupta 6 , Padmashree C.G. Rida 1 , Ritu Aneja 1, 7 1 Department of Biology, Georgia State University, Atlanta, GA 30303, USA 2 Department of Gynecologic Oncology, Northside Hospital Cancer Institute, Atlanta, GA 30342, USA 3 Department of Pathology, Emory University Hospital, Atlanta, GA 30322, USA 4 Department of Mathematics and Statistics, Georgia State University, Atlanta, GA 30303, USA 5 Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA 6 Clinical Pathology & Anatomic Pathology, West Georgia Hospitals, LaGrange, GA 30240, USA 7 Institute of Biomedical Sciences, Georgia State University, Atlanta, GA 30303, USA Correspondence to: Padmashree C.G. Rida, e-mail: cgp_rida@yahoo.com Ritu Aneja, e-mail: raneja@gsu.edu Keywords: centrosome amplification, triple negative breast cancer, metastasis, disease prognosis Received: January 21, 2015      Accepted: February 16, 2015      Published: March 19, 2015 ABSTRACT Centrosome amplification (CA), a cell-biological trait, characterizes pre-neoplastic and pre-invasive lesions and is associated with tumor aggressiveness. Recent studies suggest that CA leads to malignant transformation and promotes invasion in mammary epithelial cells. Triple negative breast cancer (TNBC), a histologically-aggressive subtype shows high recurrence, metastases, and mortality rates. Since TNBC and non-TNBC follow variable kinetics of metastatic progression, they constitute a novel test bed to explore if severity and nature of CA can distinguish them apart. We quantitatively assessed structural and numerical centrosomal aberrations for each patient sample in a large-cohort of grade-matched TNBC ( n = 30) and non-TNBC ( n = 98) cases employing multi-color confocal imaging. Our data establish differences in incidence and severity of CA between TNBC and non-TNBC cell lines and clinical specimens. We found strong correlation between CA and aggressiveness markers associated with metastasis in 20 pairs of grade-matched TNBC and non-TNBC specimens ( p < 0.02). Time-lapse imaging of MDA-MB-231 cells harboring amplified centrosomes demonstrated enhanced migratory ability. Our study bridges a vital knowledge gap by pinpointing that CA underlies breast cancer aggressiveness. This previously unrecognized organellar inequality at the centrosome level may allow early-risk prediction and explain higher tumor aggressiveness and mortality rates in TNBC patients.

UNLABELLED: This study tested whether hepatic steatosis sensitizes liver to toxicant-induced injury and investigated the potential mechanisms of hepatotoxic sensitivity. Male Sprague-Dawley rats were fed a methionine- and choline-deficient diet for 31 days to induce steatosis. On the 32nd day, administration of a nonlethal dose of CCl4 (2 mL/kg, intraperitoneally) yielded 70% mortality in steatotic rats 12-72 hours after CCl4 administration, whereas all nonsteatotic rats survived. Neither CYP2E1 levels nor covalent binding of [14C] CCl4-derived radio-label differed between the groups, suggesting that increased bioactivation is not the mechanism for this amplified toxicity. Cell division and tissue repair, assessed by [3H]thymidine incorporation and proliferative cell nuclear antigen assay, were inhibited in the steatotic livers after CCl4 administration and led to progressive expansion of liver injury culminating in mortality. The hypothesis that fatty hepatocytes undergo cell cycle arrest due to (1) an inability to replenish ATP due to overexpressed uncoupling protein-2 (UCP-2) or (2) induction of growth inhibitor p21 leading to G1/S phase arrest was tested. Steatotic livers showed 10-fold lower ATP levels due to upregulated UCP-2 throughout the time course after CCl4 administration, leading to sustained inhibition of cell division. Western blot analysis revealed an up-regulation of p21 due to overexpression of TGF beta1 and p53 and down-regulation of transcription factor Foxm 1b in steatotic livers leading to lower phosphorylated retinoblastoma protein. Thus, fatty hepatocytes fail to undergo compensatory cell division, rendering the liver susceptible to progression of liver injury. CONCLUSION: Impaired tissue repair sensitizes the steatotic livers to hepatotoxicity.

BACKGROUND: Amplified centrosomes in cancers are recently garnering a lot of attention as an emerging hub of diagnostic, prognostic and therapeutic targets. Ovarian adenocarcinomas commonly harbor supernumerary centrosomes that drive chromosomal instability. A centrosome clustering molecule, KIFC1, is indispensable for the viability of extra centrosome-bearing cancer cells, and may underlie progression of ovarian cancers. METHODS: Centrosome amplification in low- and high- grade serous ovarian adenocarcinomas was quantitated employing confocal imaging. KIFC1 expression was analyzed in ovarian tumors using publically-available databases. Associated grade, stage and clinical information from these databases were plotted for KIFC1 gene expression values. Furthermore, interactions and functional annotation of KIFC1 and its highly correlated genes were studied using DAVID and STRING 9.1. RESULTS: Clinical specimens of ovarian cancers display robust centrosome amplification and deploy centrosome clustering to execute an error-prone mitosis to enable karyotypic heterogeneity that fosters tumor progression and aggressiveness. Our in silico analyses showed KIFC1 overexpression in human ovarian tumors (n = 1090) and its upregulation associated with tumor aggressiveness utilizing publically-available gene expression databases. KIFC1 expression correlated with advanced tumor grade and stage. Dichotomization of KIFC1 levels revealed a significantly lower overall survival time for patients in high KIFC1 group. Intriguingly, in a matched-cohort of primary (n = 7) and metastatic (n = 7) ovarian samples, no significant differences in KIFC1 expression were detectable, suggesting that high KIFC1 expression may serve as a marker of metastases onset. Nonetheless, KIFC1 levels in both primary and matched metastatic sites were significantly higher compared to normal tissue . Ingenuity based network prediction algorithms combined with pre-established protein interaction networks uncovered several novel cell-cycle related partner genes on the basis of interconnectivity, illuminating the centrosome clustering independent agenda of KIFC1 in ovarian tumor progression. CONCLUSIONS: Ovarian cancers display amplified centrosomes, a feature of aggressive tumors. To cope up with the abnormal centrosomal load, ovarian cancer cells upregulate genes like KIFC1 that are known to induce centrosome clustering. Our data underscore KIFC1 as a putative biomarker that predicts worse prognosis, poor overall survival and may serve as a potential marker of onset of metastatic dissemination in ovarian cancer patients.