TCF4 silencing sensitizes the colon cancer cell line to oxaliplatin as a common chemotherapeutic drug

Abstract

Colon cancer is among the most prevalent cancers worldwide. Although the main modality of treatment is surgery, resistance to chemoradiotherapy raises concerns. Hence, we aimed to determine the effect of RNA-mediated silencing of tcf4, the downstream effector of the wnt signaling pathway, on the response of the SW480 cell line to oxaliplatin, a common chemotherapeutic drug. For this, two different silencing sequences against TCF4 mRNA were selected and cloned into pSilencer neo2.1. The SW480 cell line was stably transfected with the silencing constructs (namely p1396, p1874, and p silencer containing a scrambled sequence) and labeled SW1396, SW1874, and SW-Sc, respectively. Subsequently, the effect of oxaliplatin (from 0 to 11.25 μmol/l) on these cells was studied using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide proliferation assay. Suppression of tcf4 expression in stable transfected cells with p1396 and p1874 was confirmed by quantitative reverse transcription-PCR and western blot analysis. Although oxaliplatin was not toxic to SW480 and SW-sc in the range tested, in SW1396 and SW1874 cells, a toxic effect was evident at 3.75 and 4.375 μmol/l. Also, SW1396 and SW1874 cells appeared to have a round shape in comparison with SW480 and SW-Sc cells. Only for SW1396, the number of apoptotic cells was significantly different before and after the addition of oxaliplatin (LC50 of oxaliplatin). The proliferating cells in SW480, SW1874, and SW-Sc increased after treatment with oxaliplatin; however, this was not observed in SW1396. Although silencing the tcf4 gene would confer sensitivity to oxaliplatin in SW1874 and especially SW1396, in SW480 and SW-Sc, the lethal effect of oxaliplatin was compensated by its effect in increasing the proliferation of cells. This sensitization effect may be because of different mechanisms including TCF4 motifs in the ABCB1 promoter or defects in nucleotide excision repair or double-strand break repair systems after tcf4 silencing.

miR-203 downregulates Yes-1 and suppresses oncogenic activity in human oral cancer cells

“…DIO2 encoded the type II iodothyronine deiodinase (31) and is associated with the carcinogenesis in mesothelioma (32) and malignant thyroid tumors (33). In addition, the silencing TCF4, which is known as immunoglobulin transcription factor 2 (34), sensitize the colon cancer (35). Furthermore, IL-15 is well known as a cytokine associated anti-cancer effects (36).…”

Exosome-derived microRNAs contribute to prostate cancer chemoresistance

“…Some studies indicated that TCF4 functions to promote cellular proliferation (44,45). TCF4 silencing sensitizes the CRC line to L-OHP as a common chemotherapeutic drug (46). Hereby, TCF4 was related to hsa-miR-606, -381 and -429.…”

SW480 colorectal cancer cells that naturally express Lgr5 are more sensitive to the most common chemotherapeutic agents than Lgr5-negative SW480 cells

“…There are some data that support this hypothesis by showing that blocking Lgr5 expression using inhibitory RNA increases the chemosensitivity of colon cancer cells and that overexpression of Lgr5 is correlated with chemoresistance, presumably through the control of promoters for multidrug resistance-determining transporters like ABCB1 [4][5][6]. As Wnt/β-catenin signaling is required to support stemness, inhibition of Wnt signaling is expected to increase the sensitivity of CRC cells to cytotoxic therapy; indeed, supporting data were obtained by some researchers [7,8]. Other authors, however, have discovered that Lgr5-expressing cells are more sensitive to anticancer drugs [9,10].…”

“…This is why cell culture work and immunohistochemical analysis of genes that are influenced by Lgr5 expression are of paramount importance. Considering the Wnt signaling-dependent mechanism of some Lgr5 functions, it is noteworthy that inhibition of Tcf4 expression sensitizes SW480 cells to oxaliplatin by inducing apoptosis [8]. The mechanism of sensitization by Lgr5 needs further investigation.…”