Improvement of 5-Fluorouracil Chemosensitivty In Colorectal Cancer Cells by siRNA-Mediated Silencing of STAT6 Oncogene

Abstract

Abstract Background: One of the cancers that occur most frequently around the world is colorectal cancer (CRC). STAT6 transcription factor is involved in cellular multipotency, tumor cell growth, drug resistance, stemness, and migration, showing potential as a cancer therapy target for a variety of cancers, including CRC. In this regard, the current study aimed to investigate the effect of STAT6 silencing via small interference RNA (siRNA) in combination with 5-FU on CRC development. Methods: The MTT assay and the Annexin V/PI staining were used to examine cell proliferation and apoptosis induction, respectively. Flow cytometry was performed to investigate cell cycle progression. Wound healing assays were also used to examine HT-29 cell migration. A colony formation assay was used to examine cell stemness features of HT-29 cells. The qRT-PCR was used to measure the gene expression levels in the samples. Results: Apoptosis induction by STAT6 inhibition significantly improved the HT-29 cell chemosensitivity to 5-FU. Both caspase-9 apoptotic gene and Bax/Bcl-2 ratio were upregulated when STAT6 suppression and 5-FU were combined. Additionally, combination therapy led to cell cycle arrest at the sub-G1 phase in CRC cells. The combined therapy also significantly reduced MMP9 expression, which in turn reduced the migration of HT-29 cells. Furthermore, STAT6 knockdown inhibited HT-29 cell colony formation by reducing the expression of the Sox2 and CD44 genes, either alone or in combination with 5-FU. Conclusions: The findings show that combination therapy of 5-FU and STAT6 silencing may be an effective treatment for patients with CRC.