MEOX2 mediates cisplatin resistance in ovarian cancer via E2F target and DNA repair pathways

Abstract

Ovarian cancer (OV) is a leading cause of cancer-related mortality among women worldwide. Despite the success of platinum-based chemotherapy in treating OV, the emergence of cisplatin resistance has significantly compromised its therapeutic efficacy. Therefore, understanding the mechanisms underlying cisplatin resistance and its molecular regulation is crucial for improving patient outcomes. This study, MEOX2 was identified as a key gene significantly associated with prognosis and cisplatin resistance in OV through bioinformatics analysis. Its expression level and biological functions were validated using online databases, tissue microarrays, and cellular experiments. The results demonstrated that high MEOX2 expression was closely associated with poor survival outcomes in OV patients, while its expression was significantly reduced in cisplatin-resistant cells. Further gene silencing experiments revealed that silencing MEOX2 markedly enhanced cisplatin resistance in resistant cells and significantly reduced cisplatin-induced early apoptosis, although it had no notable effect on cell proliferation. Moreover, the study showed that MEOX2 was not associated with immune cell infiltration in OV but was positively correlated with angiogenesis-related genes. In cisplatin-resistant cells, gene set enrichment analysis of MEOX2 co-expressed genes highlighted the activation of the E2F target and DNA repair pathway. Additionally, MEOX2 exhibited a significant negative correlation with the MCM protein family. In summary, MEOX2 is highly expressed in OV and is associated with poor patient prognosis. It may confer cisplatin resistance to OV cells by activating the E2F target and DNA repair pathway to mitigate cisplatin-induced early apoptosis. Despite certain limitations, these findings provide novel insights into the potential role of MEOX2 as a prognostic biomarker and therapeutic target in OV.

Keywords: Cisplatin resistance; MEOX2; Ovarian cancer; Prognosis; Transcriptomic analysis.

Fig. 1

Screening of dual genes for OV occurrence and drug resistance. (A) PCA of the expression profiles of tumor and normal tissues. (B) DEGs between tumor and normal tissues. (C) PCA of cisplatin-sensitive and cisplatin-resistant cells in GSE15372 dataset. (D) DEGs between cisplatin-sensitive and cisplatin-resistant cells. (E) The Venn diagram of DEGs. (F) KEGG pathway analysis of intersecting genes

Fig. 2

Screening for key genes for OV survival. (A) Cox univariate analysis of DEGs. (B) Random forest model prediction of DEGs significantly associated with survival. (C) Venn diagram for the selection of core genes associated with survival in OV

Fig. 3

The expression of key genes is associated with both the survival and staging of OV. (A) Survival prognosis analysis. (B) Gene expression levels across different stages of OV

Fig. 4

The expression of MEOX2 in OV tissue microarrays and its correlation with clinical data. (A) Representative images of positive staining and corresponding scoring (scale bar = 200 μm). (B) Positive staining score and cell proportion. (C) Survival curves of overall survival and disease-free survival for patients with MEOX2. (D) Cox analysis of MEOX2 with clinical data

Fig. 5

In vitro validation of MEOX2 expression levels and function. (A) MEOX2 expression levels in different cell lines based on the HPA database. (B) The sensitivity of IOSE-80, A2780, and A2780-DDP cells to cisplatin was evaluated using the CCK-8 assay, and IC50 values were calculated for comparison. (C) MEOX2 protein expression in IOSE-80, A2780, and A2780-DDP cells was evaluated by Western blot analysis. (D) The relative mRNA expression levels of MEOX2 in A2780 and A2780-DDP cells were determined by qPCR, normalized to the expression levels in IOSE-80 cells. (E-F) The knockdown efficiency of MEOX2 in A2780-DDP cells was validated by qPCR (E) and Western blot (F), showing changes in mRNA and protein expression. (G) The impact of MEOX2 knockdown on cisplatin sensitivity in A2780-DDP cells was evaluated, as reflected by changes in IC50 values. (H) Cell viability was measured in different groups treated with 5 μM cisplatin (DDP) or untreated (NC), normalized to the viability of IOSE-80 cells. The inset graph illustrates the effects of cisplatin treatment on cell viability, excluding interference from initial viability differences among groups. (I) Apoptosis rates in different cell groups were analyzed using flow cytometry after cisplatin treatment, including total apoptosis (All apoptosis), early apoptosis (Early apoptosis), and late apoptosis (Late apoptosis). (J) The effect of MEOX2 knockdown on the migratory ability of A2780-DDP cells was assessed using a wound healing assay, comparing migration distances at 0 h and 24 h (scale bar = 100 μm; labelled as a red line). All experiments were performed in triplicate, and data are presented as mean ± standard deviation (Mean ± SD). For statistical annotations in Figures H and I, Greek letters (α, β, γ, δ) of the same color represent the groups being compared, with different letters indicating statistically significant differences between groups

Fig. 6

MEOX2 and its relationship with the tumor microenvironment. (A) Correlation analysis between MEOX2 and immune cell infiltration in OV. (B) Correlation analysis between MEOX2 and angiogenesis-related genes. (C) Correlation analysis plot of genes significantly correlated with MEOX2

Fig. 7

GSEA analysis involved in co-expressed genes with MEOX2 in cisplatin-resistant cells. (A) GSEA enrichment analysis of MEOX2 co-expressed genes. (B) GSEA analysis showing activation of the E2F targets pathway in resistant cells. (C-D) Differential distribution of enriched genes in the E2F targets pathway between resistant and sensitive OV cells (C) and their PPI network analysis (D). Targets up-regulated in resistant cells are indicated as red nodes and down-regulated targets are indicated as blue nodes