title: Genome Wide Expression Profiling of Cancer Cell Lines Cultured in Microgravity Reveals Significant Dysregulation of Cell Cycle and MicroRNA Gene Networks.
abstract: Zero gravity causes several changes in metabolic and functional aspects of the human body and experiments in space flight have demonstrated alterations in cancer growth and progression. This study reports the genome wide expression profiling of a colorectal cancer cell line-DLD-1, and a lymphoblast leukemic cell line-MOLT-4, under simulated microgravity in an effort to understand central processes and cellular functions that are dysregulated among both cell lines. Altered cell morphology, reduced cell viability and an aberrant cell cycle profile in comparison to their static controls were observed in both cell lines under microgravity. The process of cell cycle in DLD-1 cells was markedly affected with reduced viability, reduced colony forming ability, an apoptotic population and dysregulation of cell cycle genes, oncogenes, and cancer progression and prognostic markers. DNA microarray analysis revealed 1801 (upregulated) and 2542 (downregulated) genes (>2 fold) in DLD-1 cultures under microgravity while MOLT-4 cultures differentially expressed 349 (upregulated) and 444 (downregulated) genes (>2 fold) under microgravity. The loss in cell proliferative capacity was corroborated with the downregulation of the cell cycle process as demonstrated by functional clustering of DNA microarray data using gene ontology terms. The genome wide expression profile also showed significant dysregulation of post transcriptional gene silencing machinery and multiple microRNA host genes that are potential tumor suppressors and proto-oncogenes including MIR22HG, MIR17HG and MIR21HG. The MIR22HG, a tumor-suppressor gene was one of the highest upregulated genes in the microarray data showing a 4.4 log fold upregulation under microgravity. Real time PCR validated the dysregulation in the host gene by demonstrating a 4.18 log fold upregulation of the miR-22 microRNA. Microarray data also showed dysregulation of direct targets of miR-22, SP1, CDK6 and CCNA2.
authors: Stem cell and Molecular Biology laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India.
authors: Prasanna
authors: P
authors: Vidyasekar
authors: Stem cell and Molecular Biology laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India.
authors: Pavithra
authors: P
authors: Shyamsunder
authors: Stem cell and Molecular Biology laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India.
authors: Rajpranap
authors: R
authors: Arun
authors: Stem cell and Molecular Biology laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India.
authors: Rajalakshmi
authors: R
authors: Santhakumar
authors: Department of cardiothoracic Surgery, Global Hospital, Perumbakkam, Chennai, India.
authors: Nand Kishore
authors: NK
authors: Kapadia
authors: Department of cardiology, Fortis Malar Hospital, Adyar, Chennai, India.
authors: Ravi
authors: R
authors: Kumar
authors: Stem cell and Molecular Biology laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India.
authors: Rama Shanker
authors: RS
authors: Verma
mesh_terms: D002453:Cell Cycle / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D053263:Gene Regulatory Networks; D015894:Genome, Human; D055106:Genome-Wide Association Study; D006801:Humans; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D018474:Weightlessness Simulation
chemical_list: D018797:Cell Cycle Proteins; D035683:MicroRNAs; D011518:Proto-Oncogene Proteins