SOX2 knockdown with siRNA reverses cisplatin resistance in NSCLC by regulating APE1 signaling

Abstract

SOX2 is related to drug resistance in many types of cancer, including lung cancer. Herein, we investigated the role of SOX2 and its regulatory signaling in cisplatin-treated non-small-cell lung cancer (NSCLC). The effects of SOX2 on cell viability, proliferation, and apoptosis were evaluated in vitro. Western blotting, real-time quantitative PCR, immunohistochemistry, and luciferase reporter assays were used to investigate the underlying mechanism. Kaplan–Meier survival analysis and the log-rank test were used to assess the relationship between SOX2 expression and patient survival. A549/CDDP cells had marked resistance to cisplatin and stronger colony formation ability than A549 cells. The expression of SOX2 protein or mRNA in A549/CDDP was higher than that in A549. Knockdown of SOX2 in A549/CDDP-induced apoptosis by inhibiting colony formation and decreasing viability, but overexpression of SOX2 reversed these effects. Interestingly, Genomatix software predicted that the APE1 promoter has some SOX2 binding sites, while the SOX2 promoter has no APE1 binding sites. Furthermore, luciferase reporter assays proved that SOX2 could bind the promoter of APE1 in 293T cells. We further verified that SOX2 expression was not affected by shAPE1 in A549/CDDP. As expected, colony formation was obviously inhibited and apoptosis was strongly enhanced in A549/CDDP treated with SOX2 siSOX2 alone or combined with CDDP compared with control cells. Meaningfully, patients with low expression of SOX2, and even including its regulating APE1, survived longer than those with high expression of SOX2, and APE1. siSOX2 overcomes cisplatin resistance by regulating APE1 signaling, providing a new target for overcoming cisplatin resistance in NSCLC.

SOX2 Expression Does Not Guarantee Cancer Stem Cell-like Characteristics in Lung Adenocarcinoma

“…In this study, we generated knockout and conditional knockdown of SOX2 in LUAD cell lines through the CRISPR/Cas9 (Cas9) and doxycycline-inducible shRNA techniques, respectively. Through multiple loss-of-function experiments using the complete knockout cells, we were able to provide evidence that SOX2 is dispensable for CSC-like traits in LUAD cells, which contradicts previous findings [19][20][21][22]. Our shSOX2 cell lines with SOX2 reconstitution strongly suggest a potential misinterpretation of previous findings based on transient knockdown using siRNA or shRNA.…”

“…Previous reports have asserted that SOX2 functions as a key regulator of CSC-like characteristics of LUAD. Multiple studies have shown that the reduction of SOX2 expression using shRNA or siRNA leads to decreased proliferation and CSC-like characteristics in various LUAD cell lines [19][20][21][22]. However, these findings were derived from specific cell lines or through siRNA or shRNA methods, potentially introducing off-target activities.…”

Prominin 2 decreases cisplatin sensitivity in non-small cell lung cancer and is modulated by CTCC binding factor

“… 24 It has been reported that many RNAs and proteins participate in modulating cisplatin resistance in NSCLC patients. 25 , 26 Recently, Li et al . have demonstrated that PROM2 promotes gemcitabine chemoresistance via activating the Akt signaling pathway in pancreatic cancer.…”

SOX2 regulates paclitaxel resistance of A549 non‑small cell lung cancer cells via promoting transcription of ClC‑3

“…MLN4924 inhibits stem cell properties and makes cancer cells sensitive to chemotherapy by inactivating the F-box and WD repeat domain containing 2/msh homeobox 2/SOX2 axis in human lung cancer ( 36 ). Silencing of SOX2 increases the sensitivity to cisplatin in NSCLC by regulating apurinic/apyrimidinic endonuclease 1 signaling ( 26 ). The present study revealed that the mRNA and protein expression levels of SOX2 were increased in A549-PTX cells.…”

“…SRY-box transcription factor 2 (SOX2) is not only a pluripotent stem cell-related factor but also a key transcription factor and serves a role in maintaining stem cell properties and determining the fate of cells ( 23 ). Researchers have revealed that SOX2 is aberrantly expressed in different types of cancer and that SOX2 expression is positively associated with cancer cell stemness and multi-drug resistance ( 24 – 26 ). Therefore, SOX2 may be an attractive therapeutic target for overcoming chemotherapy resistance.…”