INTRODUCTION: The H1047R mutation is the most frequent cancer-specific mutation in the catalytic subunit p110α of Class 1A PI3K. Our previous reports have shown that the H1047R is a gain-of-function mutation that increases colorectal cancer (CRC) cell migration & cancer metastasis. We have also shown that H1047R mutation may increases CRC HCT116 cell migration via actin cytoskeleton reorganization & cell morphology change. The actin cytoskeleton is a dynamic structure which is controlled or mediated by a number of small molecules & actin-binding proteins. The purpose of this study was to determine the differential gene expression profiles in CRC cells with either wild type (WT) or H1047R mutant (MUT) PIK3CA.
METHODS: HCT116 cells engineered to contain either MUT or WT PI3KCA allele were used in this study. Total RNA was extracted from the two isogenic cell lines by commercial isolation reagents. RNA sequencing was used to identify the specific alterations in gene expression profiling of the cells. The raw RNA-seq reads were preprocessed through a customized analysis pipeline & summarized to gene level feature counts. The differential expression gene (DEG) analysis was performed using R & Bioconductor packages including edgeR.
RESULTS: At significance levels false discovery rate (FDR) = 0.05, we identified 89 DEGs whose fold changes (FC) are greater than 2. Among the 89 DEGs, 49 are up-regulated & 40 are down-regulated by H1047R mutation. By GO (Gene Ontology) category pathway analysis, the H1047R mutation mediated gene expression alteration are involved in 26 pathways including cell migration, regulation of cell communication, cell surface receptor signaling pathway, morphogenesis, regulation of signaling & cell-cell signaling pathways. For example, the upregulated VCA (Versican) & EPHA4 (EPH Receptor A4) play important roles in controlling cell migration. CTEN/TNS4 was also upregulated, which localizes to focal adhesions & induces cell motility. On the other hand, the downregulated ARHGAP18 is a coding gene of Rho GTPase Activating Protein 18 which suppresses F-actin polymerization by inhibiting Rho, thereby regulating cell shape, spreading, & migration.
CONCLUSION: The H1047R mutation induced specific alterations in gene expression profiling of CRC HCT116 cells have been detected. These changes appear to contribute to more aggressive cancer cell behavior. These results will guide further studies on the molecular mechanisms underlying H1047R-p110α mediated CRC metastasis. Understanding these mechanisms may allow for the development of novel therapeutic strategies for patients who bear the H1047R mutation.
Citation Format: Guanghua Wan, Huining Kang, Scott Ness, Alissa Greenbam, Ashwani Rajput. H1047R mutation of p110 alpha alters expression level of genes which are associated with cell migration & cancer metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-077. doi:10.1158/1538-7445.AM2017-LB-077