Madhavi Kadakia (Advisor), Weiwen Long (Committee Member), Hongmei Ren (Committee Member)
Master of Science (MS)
DNp63a, a member of the p53 family of transcription factors, is overexpressed in a number of cancers and known to play a role in proliferation, differentiation, migration and invasion. DNp63a has been shown to regulate several microRNAs that play a role in both development and cancer, but to date there has not been a global analysis of p63- regulated miRNA. Using next-generation sequencing of small RNA from wild type and sip63 transfected HaCaT cells, our laboratory recently identified a number of DNp63a- regulated miRNAs by RNA-Seq studies which may serve as biomarkers of cancer progression. We identified a novel miRNA, miR-320a which is positively regulated by p63. Previous studies have shown that miR-320a is downregulated in colorectal cancer and targets Ras-related C3 botulinum toxin substrate 1 (RAC1), leading to a decrease in non- canonical WNT signaling and EMT and thereby a corresponding decrease in tumor metastasis and invasion. We hypothesize that DNp63a decreases cell invasion through down-regulation the activity of Rac1 via miR-320a. We showed that knockdown of DNp63a in HaCaT and A431 cell lines lead to a decrease in miR-320a levels and a corresponding increase in the phosphorylation of Rac1 at Ser71, while overexpression of DNp63a in SW480 and Caco2 cells led to a decrease in the S71 phosphorylation of Rac1. We also showed that DNp63a effect the GTP activity of Rac1. Knockdown of DNp63a showed significant increase in Rac1 GTP levels and subsequent increase the activity of its effector PAK1. Finally, we showed that the increase observed upon knockdown of DNp63a is reversible by overexpressing miR-320a. Taken together, our data suggest that DNp63a-mediated increase in miR-320a levels has potential implications for cancer migration and metastasis.
Department or Program
Biochemistry and Molecular Biology
Year Degree Awarded
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