Dataset Information

Osteopontin isoform c promotes the survival of cisplatin-treated NSCLC cells involving NFATc2-mediated suppression on calcium-induced ROS levels.

ABSTRACT:

Background

Tumor microenvironment (TME) critically contributed to the malignant progression of transformed cells and the chemical responses to chemotherapy reagents. Osteopontin (OPN) is a secretory onco-protein with several splicing isoforms, all of which were known to regulate tumor growth and able to alter cell-cell or cell-TME communication, however, the exact role and regulation of the OPN splicing isoforms was not well understood.

Methods

In this study, the effects of conditioned medium from the culture of OPN splicing isoforms overexpressing cells on cell functions were evaluated. The methods of nuclear calcium reporter assays and subcellular distribution of nuclear factor of activated T cells c2 (NFATc2) assays were used to investigate the molecular mechanism underlining the roles of OPN splicing isoforms.

Results

We found that the survival of NSCLC cells treated with cisplatin was increased by secretory OPNc in the condition medium, where reduction of apoptosis by OPNc was associated with the activation of cellular calcium signals and subsequent nuclear translocation of NFATc2.

Conclusions

The results revealed a mechanism of OPN and downstream signal for tumor cells to survive in chemo-stressed TME, which emphasized the importance of secretory proteins in alternative splicing isoforms. Our study not only demonstrated the importance of OPN neutralization for anti-tumor effects, but also implied that modulation in calcium/NFATc2/ROS axis could be a novel approach for improving the long-term outcome of NSCLC treatment.

SUBMITTER: Huang J

PROVIDER: S-EPMC8243455 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Osteopontin (OPN) is upregulated in several types of tumor and has been associated with chemoresistance. However, the contribution of OPN splicing isoforms (OPN‑SIs) to chemoresistance requires further investigation. The present study aimed to evaluate the expression patterns of each tested OPN‑SI in cisplatin (CDDP)‑resistant ovarian carcinoma cell lines, focusing on the role of the OPN‑c isoform (OPNc) in drug resistance. ACRP ovarian cancer cells resistant to CDDP, as well as their parental cell line A2780, were used. Analyses of the transcriptional expression of OPN‑SIs, epithelial‑mesenchymal transition (EMT) markers and EMT‑related cytokines were performed using reverse transcription‑quantitative PCR. OPNc was silenced in ACRP cells using anti‑OPNc DNA oligomers and stably overexpressed by transfecting A2780 cells with a mammalian expression vector containing the full length OPNc cDNA. Functional assays were performed to determine cell proliferation, viability and colony formation. The results demonstrated that among the three tested OPN‑SIs, OPNc was the most upregulated transcript in the ACRP cells compared with the parental A2780 cells. In addition, the expression levels of P‑glycoprotein multidrug transporter were upregulated in CDDP‑resistant ACRP cells compared with those in A2780 cells. OPNc knockdown sensitized ACRP cells to CDDP treatment and downregulated P‑gp expression levels compared with those in the negative control group. Additionally, silencing of OPNc impaired cell proliferative and colony formation abilities, as well as reversed the expression levels of EMT markers and EMT‑related cytokines compared with those in the negative control cells. Notably, although stable OPNc overexpression resulted in increased A2780 cell proliferation, it notably increased CDDP sensitivity compared with that in the cells transfected with a control vector. These results suggested that OPNc silencing may represent a putative approach to sensitize resistant ovarian cancer cells to chemotherapeutic agents.