THE SERUM DEPENDENT TRANSCRIPTOMIC AND GENE EXPRESSION ANALYSIS IN KRAS MUTANT CANCER CELLS

Abstract

Human cancers carrying KRAS mutations are considered to be highly malignant and are associated with poor prognosis, resistance to therapy, and highly adaptive to stress conditions. Nowadays, a growing body of literature indicates that a fetal bovine serum (FBS) supplement is a critical factor in cell culture medium providing growth factors and extracellular matrix components. Therefore, deprivation of this supplement is a common way to provoke stress associated with significant changes in cell growth and proliferation. The scientific community put huge effort to investigate cancer cell responses to serum deprivation and an explanation of its regulatory mechanisms. However, it is still unknown what happens with KRAS mutant cancer cells during serum deprivation. In this study, we investigated the changes of patterns ribosome/polysome profiling and transcriptomic gene expression in KRAS mutant cancer cell lines following serum deprivation. First, we studied the response of KRAS mutant cancer cells to serum deprivation by examining cell growth by cell number and cell size. Then, we performed the functional gene expression studies by performing transcriptomic analysis of the RNA obtained from total lysates and polysomal fraction. Using RNA sequencing analysis, we show that the genes involved in cholesterol and fatty acid synthesis are dramatically upregulated under serum starvation conditions in KRAS mutant cancer cells. The identified genes were further validated by the Q-PCR application. It is likely, we observe a main adaptive serum depletion response to compensate an abundance of cholesterol by activation of pathway responsible for its synthesis, because serum (FBS) is a main source of lipids including cholesterol in cell culture. A cellular pathway orchestrating this process is yet to be defined. The results of this study provide a better understanding of the molecular mechanism underlying the adaptation and survival of KRAS mutant cancer cells under serum deprived condition, understanding the biology of cancer cells behavior that in future may lead to development of novel therapeutic strategies for the treatment of KRAS mutant cancers