Differential expression of DMD transcripts as a novel prognostic biomarker in histologically diverse mesotheliomas

The identification of prognostic biomarkers is crucial for guiding treatment strategies in mesothelioma patients. The Duchenne muscular dystrophy (DMD) gene and its specific transcripts have been associated with patient survival in various tumours. In this study, we aimed to investigate the prognostic potential of DMD gene expression and its transcripts in mesothelioma patients.

We analysed The Cancer Genome Atlas (TCGA) mesothelioma RNAseq, mutation, and clinical data to assess the association between DMD gene expression and its transcripts (Dp427, Dp71 splice variants) and mesothelioma survival. We also evaluated the specific Dp71 transcript as a unique prognostic biomarker across mesothelioma subtypes. Additionally, we performed differential gene expression analysis between high and low DMD gene/transcript expression groups.

The analysis included 57 epithelioid, 23 biphasic, two sarcomatoid, and five not otherwise specified (NOS) histological subtypes of mesothelioma samples. Univariate analysis revealed that high expression of the DMD gene and its Dp71 transcript was significantly associated with shorter survival in mesothelioma patients (P=0.003 and P<0.001, respectively). In a multivariate analysis, the association between Dp71 expression and survival remained significant [hazard ratio (HR) 2.29, 95% confidence interval (CI): 1.24-4.23, P=0.008] across all mesothelioma patients, and also among patients with mesotheliomas without deep CDKN2A deletions (HR 3.58, 95% CI: 1.31-9.80, P=0.01). Pathway analysis revealed enrichment of cell cycle (P=3.01×10^-4) and homologous recombination (P=0.01) pathways in differentially expressed genes (DEGs) between high and low Dp71 groups. Furthermore, there were correlations between Dp71 transcript expression and tumour microenvironment (TME) cells, including a weak positive correlation with macrophages (R=0.32, P=0.002) specifically M2 macrophages (R=0.34, P=0.001).

Our findings indicate that the differential expression of specific DMD transcripts is associated with poor survival in mesothelioma patients. The specific Dp71 transcript can serve as a potential biomarker for predicting patient survival in diverse histological subtypes of mesothelioma. Further studies are needed to understand the role of specific dystrophin transcripts in cancer and TME cells, and their implications in the pathogenesis and progression of mesothelioma. Identifying patients at risk of poor survival based on DMD transcript expression can guide treatment strategies in mesothelioma, informing decisions regarding treatment intensity, follow-up schedules, eligibility for clinical trials, and ultimately, end-of-life care planning.