The highly refractory nature of non-small cell lung cancer (NSCLC) to chemotherapeutic drugs is an important factor resulting in its poor prognosis. Recent studies have revealed that tumour necrosis factor alpha-induced protein 8 (TNFAIP8) is involved in various biological and pathological processes of cells, but their underlying mechanisms in processes ranging from cancer development to drug resistance have not been fully elucidated. TNFAIP8 expression in clinical NSCLC samples was examined through immunohistochemistry (IHC). After adjusting for patients’ characteristics with propensity score matching, Kaplan-Meier analysis and Cox regression analysis were performed for comparison of patients’ survival according to the TNFAIP8 level. Lentiviral transfection with TNFAIP8-specific shRNAs was used to establish stable TNFAIP8 knockdown (TNFAIP8 KD) NCI-H460, A549 and cis-diamminedichloroplatinum II resistant A549 (A549/cDDP) cell lines. Cell proliferation and viability were assessed by CCK-8 assay. Cell cycle was examined by flow cytometry. Multiple pathways regulated by TNFAIP8 KD were revealed by microarray analysis. We found that high TNFAIP8 expression was associated with advanced pT stage, advanced pTNM stage, lymph node metastasis and unfavourable survival in NSCLC patients. TNFAIP8 shRNAs reduced in vitro cancer cell proliferation and in vivo tumor growth. Additionally, TNFAIP8 KD increased the sensitivity of NSCLC cells to cisplatin in vitro and in vivo. Conversely, up-regulation of TNFAIP8 promoted the proliferation and drug resistance to cisplatin of NSCLC cells. TNFAIP8 influences cancer progression pathways involving the MDM2/p53 pathway. Indeed, we observed that TNFAIP8 KD mediated the MDM2 downregulation and the p53 ubiquitination, thereby decreasing the degradation of p53 protein. shRNA p53 reversed TNFAIP8 shRNA-mediated regulation of cell proliferation, cell cycle, cisplatin sensitivity, and expression levels of RAD51, a DNA repair gene. Our work uncovers a hitherto unappreciated role of TNFAIP8 in NSCLC proliferation and cisplatin chemoresistance that is mediated through the MDM2/p53 pathway. These findings might offer potential therapeutic targets for reversing cisplatin resistance in NSCLC patients with high TNFAIP8 expression.

TRIM44 promotes proliferation and metastasis in non‑small cell lung cancer via mTOR signaling pathway

Alternative splicing (AS) generates protein diversity and is exploited by cancer cells to drive tumor progression and resistance to many cancer therapies, including chemotherapy. SNRPA is first identified as a spliceosome‐related gene that potentially modulates resistance to platinum chemotherapy. Both the knockout or the knockdown of SNRPA via CRISPR/Cas9 and shRNA techniques can reverse the resistance of cisplatin‐resistant lung adenocarcinoma (LUAD) cells to cisplatin. SNRPA overexpression enhanced the resistance of cisplatin‐sensitive LUAD cells. Gene Ontology (GO) analysis reveals that SNRPA is associated with DNA damage repair. Depletion of SNRPA induced ERCC1 exon 8 skipping and reduced ERCC1–XPF complex formation, whereas SNRPA overexpression exerted the opposite effect. siRNAs targeting isoforms containing ERCC1 exon 8 [ERCC1‐E8 (+)] reversed SNRPA‐enhanced cisplatin resistance and DNA damage repair. Furthermore, the IGF2BP protein, an m ⁶ A reader, and the ELAVL1 protein, an RNA stabilizer recruited by IGF2BP1, are found to bind to the SNRPA mRNA. ELAVL1 promoted cisplatin resistance, DNA repair and ERCC1‐E8 (+) expression in an SNRPA‐dependent manner. In a mouse xenograft model, SNRPA‐ KO CRISPR enhanced the sensitivity of LUAD cells to cisplatin. Overall, this study illuminates the role of SNRPA in platinum‐based drug resistance, thereby providing a novel avenue to potentially enhance chemosensitivity and improve the prognosis of patients with LUAD.

Tripartite motif-containing 44 (TRIM44) has recently been implicated in various pathological processes in numerous cancers, including lung adenocarcinoma (LUAD); however, its functional roles in chemoresistance are poorly understood. Herein, TRIM44 knockdown sensitized LUAD cells to cisplatin and enhanced cisplatin-induced apoptosis. Microarray analysis indicated that the “Role of BRCA1 in DNA damage” and the BRCA1 gene expression were positively regulated by TRIM44, which was further verified by immunofluorescence, qRT-PCR, and Western blotting. BRCA1 depletion effectively abolished TRIM44-modulated cisplatin resistance and regulation of homologous recombination (HR) repair. Interestingly, TRIM44 interacted with FLNA, an upstream regulator of BRCA1 as specified by STRING V 11.5, and facilitated its stability and deubiquitination. FLNA was also found to be required for the functions of TRIM44 in drug resistance. Using animal models, overexpression of TRIM44 was shown to confer resistance to cisplatin in a BRCA1- and FLNA-dependent manner. TRIM44 expression levels in tissues from cisplatin-resistant LUAD patients were significantly higher than those in tissues from cisplatin-sensitive LUAD patients. Collectively, our study results demonstrate that the TRIM44/FLNA/BRCA1 axis is involved in cisplatin chemoresistance, providing potential therapeutic targets for LUAD patients with cisplatin resistance.