Research in our laboratory is focused on studying the
molecular mechanisms that control tumor growth and progression.
Our research is concentrated in two principal areas:
1) Understanding the role of cellular signaling pathways involved in cancer stemness and malignant behavior of Central Nervous System (CNS) tumors.
2) Deciphering mechanisms through which long non-coding RNAs mediate cell growth regulation and homeostasis.
Mechanisms of Growth Suppression induced by NRAGE over-expression
Understanding the role of cellular signaling pathways involved in cancer stemness and malignant behavior of CNS tumors
Malignant gliomas are one of the most aggressive and invasive tumors of CNS, refractive to treatment and displaying poor prognosis. The tumors display high level of phenotypic heterogeneity due to presence of diverse population of cells termed as BTSCs or BTICs (brain tumor stem/initiating cells) demonstrating hierarchical organization and exhibiting tumor forming potential. While, cell of origin for gliomas is not yet clearly defined, various findings like localization of glial tumor close to the sub-ventricular zone (SVZ) region in the brain, capacity of BTICs to self-renew, undergo multi-lineage differentiation and activate similar developmental signaling pathways that regulate stem cell properties strongly supports the concept that gliomas arise by malignant transformation of neural stem or progenitor cells.
Research in my lab is focusing on understanding cellular signaling mechanisms involved in malignant transformation of neural stem cells (NSC) to cancer stem cells (CSC). For this we have developed a model system comprising of a cell population that could be propagated as a long-term in vitro culture displaying all the features of neural stem cells (HNGC-1) and a cancer stem cell-line (HNGC-2) developed by spontaneous immortalization of these neural stem cells. Additionally, we have developed a series of long term cultures and cell-lines from glioma tissues enriched with a population of BTICs and have propagated them as models for understanding process of tumor progression and invasion in gliomas. With these model systems we are asking the following questions: 1). Can we generate long-term cultures from GBM tumors enriched with glioma stem cell population, and if yes can a glioma stem cell signature be established and validated using these cultures 2). Can we establish a differential gene expression profiling of the cancer stem cell and non-tumor stem cell population from glioma tumors 3). Are proteins like those belonging to MAGE family, involved in effecting cell proliferation and differentiation potential of cells derived from the neuronal and glial cell systems and 4). Elucidate complex molecular mechanisms regulating interactions of brain tumor initiating cells with the endogenous niche that promotes angiogenesis in brain tumors 6). Determine miRNA expression analyses of BTICs derived from gliomas 7). Epigenetic profiling in gliomas enriched with BTICs with reference to tumor suppressor genes and role of DNA methyl-transferases (DNMTs) - DNMT1 and DNMT3a.
Over-Activation of DNA damage pathway by Ginir leads to Cellular Transformation
Understanding mechanisms through which long non-coding RNAs can mediate cell growth regulation and homeostasis
It is now well-established that most of the human genome is transcribed into non coding RNA sequences than into protein-coding sequences. Whilst, only about 1% of human genome is protein-encoding, most of the genome is transcribed into stable non-protein-coding RNA transcripts. Many of these identified long non-coding RNAs like Evf-2, XIST, Air and HOTAIR are subjected to splicing, poly-adenylation, and other post-transcriptional modifications and their loci tend to be associated with chromatin. The regulatory control of transcription and splicing patterns, evolutionary conservation, and presence of predicted secondary structures suggest that the transcriptional products from each locus are functional. Furthermore, their spatiotemporal expression patterns suggest that these ncRNA loci might contribute to regulation of cell proliferation and differentiation programs. Using a whole genome screen for identification of oncogenes, we identified in our lab a pair of long non-coding, sense (Ginir) and anti-sense (Giniras) RNA transcripts which lack protein-coding potential and are involved in cellular growth control. Our studies indicate that while the sense transcript – Ginir acts as a genomic instability-inducing RNA (Ginir), promoting oncogenic transformation, its anti-sense counterpart (Giniras) acts as its negative regulator. This pair of naturally expressed, non-coding and overlapping, sense and anti-sense transcripts (SAST) is critical to normal cell cycle progression. We are addressing following questions in relation to these nc-RNAs: 1). Characterize role of Sense and Anti-sense transcripts – Ginir and Giniras in cell proliferation, and 2). Understand molecular mechanisms and signaling pathways elicited by this pair of Ginir and Giniras transcripts in cellular homeostasis. Collectively, our data demonstrates a novel mechanism to regulate cell cycle progression and suggest that some of the cancers might originate from deregulated expression of a pair of SAST. We propose that mechanisms like SAST may be one of the mechanisms effective in orchestrating gene regulation, chromatin remodeling, animal development and stem cell differentiation.
Dlxin-1, a MAGE family protein, induces accelerated neurite outgrowth and cell survival by enhanced and early activation of MEK and Akt signalling pathways in PC12 cells. Reddy EM, Chettiar ST, Kaur N, Shepal V, Shiras A. Exp Cell Res. 2010 Aug 15;316(14):2220-36. Epub 2010 Jun 8.
Epigenetic regulation of DNA methyltransferases: DNMT1 and DNMT3B in gliomas. Rajendran G, Shanmuganandam K, Bendre A, Muzumdar D, Goel A, Shiras A. J Neurooncol. 2011 Feb 10. [Epub ahead of print]
Rictor regulates MMP-9 activity and invasion through Raf-1-MEK-ERK signaling pathway in glioma cells. Das G, Shiras A, Shanmuganandam K, Shastry P. Mol Carcinog. 2010 Dec 28. [Epub ahead of print]
Dlxin-1, a member of MAGE family, inhibits cell proliferation, invasion and tumorigenicity of glioma stem cells. Reddy EM, Chettiar ST, Kaur N, Ganeshkumar R, Shepal V, Shanbhag NC, Shiras A. Cancer Gene Ther. 2010 Nov 26. [Epub ahead of print]
Biocompatible gellan gum-reduced gold nanoparticles: cellular uptake and subacute oral toxicity studies. Dhar S, Mali V, Bodhankar S, Shiras A, Prasad BL, Pokharkar V. J Appl Toxicol. 2010 Nov 19. doi: 10.1002/jat.1595. [Epub ahead of print]
Cytotoxicity of sophorolipid-gellan gum-gold nanoparticle conjugates and their doxorubicin loaded derivatives towards human glioma and human glioma stem cell lines. Dhar S, Reddy EM, Prabhune A, Pokharkar V, Shiras A, Prasad BL. Nanoscale. 2010 Nov 11. [Epub ahead of print]
Laminin-1 induces neurite outgrowth in human mesenchymal stem cells in serum/differentiation factors-free conditions through activation of FAK-MEK/ERK signaling pathways. Mruthyunjaya S, Manchanda R, Godbole R, Pujari R, Shiras A, Shastry P. Biochem Biophys Res Commun. 2010 Jan 1; 391(1):43-8.
Natural gum reduced/stabilized gold nanoparticles for drug delivery formulations. Dhar S, Reddy EM, Shiras A, Pokharkar V, Prasad BL. Chemistry 2008; 14(33):10244-50.
Shiras A, Chettiar S T, Shepal V, Rajendran G, Prasad G R, Shastry P. Spontaneous transformation of human adult nontumorigenic stem cells to cancer stem cells is driven by genomic instability in a human model of glioblastoma. Stem Cells. 2007 Jun;25(6):1478-89. Epub 2007 Mar 1
Sudheerkumar P, Shiras A, Das G, Jagtap JC, Prasad V, Shastry P. Independent activation of Akt and NF-kappaB pathways and their role in resistance to TNF-alpha mediated cytotoxicity in gliomas. Mol Carcinog.2008 Feb;47(2):126-36.
Kumar PS, Shiras A, Das G, Jagtap JC, Prasad V, Shastry P. Differential expression and role of p21cip/waf1 and p27kip1 in TNF-alpha-induced inhibition of proliferation in human glioma cells. Mol Cancer 2007 Jun 12;6:42
Shiras A, Bhosale A, Shepal V, Shukla R, Baburao VS, Prabhakara K, Shastry P. A unique model system for tumor progression in GBM comprising two developed human neuro-epithelial cell lines with differential transforming potential and coexpressing neuronal and glial markers. Neoplasia. 2003 Nov-Dec;5(6):520-32.
Shiras A, Bhosale A, Patekar A, Shepal V, Shastry P. Differential expression of CD44(S) and variant isoforms v3, v10 in three-dimensional cultures of mouse melanoma cell lines. Clin Exp Metastasis. 2002;19(5):445-55.
Shiras A, Sengupta A, Shepal V. Cloning and tissue-specific gene expression studies with Dlxin-1, a newly identified transcriptional activator. Mol Cell Biol Res Commun. 2001 Sep;4(5):313-9.
Shiras A, Shepal V, Bhonde M, Shastry P. S100 expression in primary mouse fibroblast cultures. In Vitro Cell Dev Biol Anim. 2001 Mar;37(3):172-4.
Inter Individual Differences in Carbamezapine handling. Yardi, N., Divekar D., Sant H., Divate P., Apte C., Singh J.P. and Shiras A., Sitasawad S., Wagh. U. (1997) Epilepsia, 38 (3) : 41-48.
Dr. Varsha Shepal, M.Sc., Ph.D.
Mr. Ganeshkumar Rajendran, SRF, Epigenetics in gliomas Ms. Sandhya BoyaRani, SRF, miRNAs in Glioma, Ms. Navjot Kaur, SRF, Non-Coding RNA in cell transformation Mr. Aman Sharma, JRF, Cancer stem cell-niche interactions Mr. Phalguni Rath, JRF, Reprogramming toward human iPS Ms. Suchismita Panda, JRF
Mr. Karthik kumar, M.Sc., Project JRF,(DBT Project) Project : miRNA in gliomas
Nikhil Pandya Amruta Tirmale Ameya Bendre Poffee Francis Swetha Srinivasan
Dr. G. Rajendra Prasad, Post Doctoral Fellow, Sidney Kimmel Comprehensive Cancer Centre at Johns Hopkins Baltimore, USA
Dr. E. Maheswara Reddy, Post Doctoral Fellow, Molecular Immunology group (Stem Cells), University of Turku and Åbo Akademi University, Turku, FINLAND.
Dr. Shivaranjan T. Chettiar, Post Doctoral Fellow, Sidney Kimmel Comprehensive Cancer Centre at Johns Hopkins Baltimore, USA