In the US, colon adenocarcinoma is the third most common cause of cancer-related deaths. Since various genetic and epigenetic alterations contribute to progression of this disease, it is necessary to evaluate these molecular events as markers of progression and as potential druggable targets to develop therapeutics. Analysis of publicly available TCGA transcriptome sequencing data using UALCAN, a bioinformatics web portal (http://ualcan.path.uab.edu/), identified in colon adenocarcinoma, overexpression of collagen prolyl-4-hydroxylase α subunit 1 (P4HA1), an enzyme involved in collagen metabolism. P4HA1 changes the composition of the extra cellular matrix by hydroxylating proline residues in collagen. We validated this in silico finding by measuring P4HA1 RNA expression levels in paired normal (n=105) and tumor (n=105) frozen samples by qRT-PCR. Our investigations showed overexpression of P4HA1 in colon cancers compared to their paired normal colonic epithelial tissues. Expression of P4HA1 was independent of pathologic stage; tumor histologic type; and the race/ethnicity, age, and gender of patients. Furthermore, Western blotting and immunohistochemical analyses showed elevated expression of P4HA1 protein in colon tumor tissues as compared to normal colonic epithelial specimens. To assess the functional role of P4HA1 in colon cancer cells, we performed in vitro and in vivo analyses using RNA interference. The results showed that depletion of P4HA1 led to reduced cell growth and cell invasion, and to less tumor growth in xenograft models. Bioinformatics analysis indicated that microRNA miR-124, a tumor suppressor, could be targeting P4HA1. Forced overexpression of miR-124 in colon cancer cells reduced P4HA1 expression and diminished the malignant phenotypes of colon cancer cells, confirming that, in these cells, miR-124 targeted P4HA1. Further, treatment of the cells with diethyl-pythiDC (100 uM), a small molecule inhibitor of P4HA1, reduced their malignant phenotypes. In sum, the present investigations show that overexpression of P4HA1 is involved in progression of colon adenocarcinomas and that it is a potential therapeutic target that is amenable to small molecule inhibition.
This work was partially supported by a NIH grant (3U54CA118948) and by the ELKUS foundation grant to Dr. Manne.
Citation Format: Sumit Agarwal, Balabhadrapatruni V. Chakravarthi, Michael Behring, Hyung-Gyoon Kim, Kevin Hale, Abduljalil M. Alsubaie, Sameer Al Diffalha, Shajan P. Sugandha, Sooryanarayana Varambally, Upender Manne. MicroRNA-124 modulated collagen-prolyl hydroxylase P4HA1 expression regulates colon cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 851.