Pan-cancer analysis reveals DNAJC9 as an immune-related biomarker and a positive regulator of the PI3K/AKT signaling pathway.

Background

Heat shock proteins (HSPs) modulate apoptosis, proliferation, and differentiation, positioning them as potential therapeutic targets in cancer. As a member of the J-domain-containing HSP40 family, DnaJ homolog, subfamily C, member 9 (DNAJC9) has not yet been systematically investigated in a pan-cancer context. Method: Multiple public repositories were employed to perform a comprehensive pan-cancer investigation of DNAJC9. We also utilized single-cell datasets to explore how DNAJC9 expression varies across distinct cellular clusters. These efforts covered several key dimensions, including diagnostic and prognostic value, immune landscape, genomic alterations, methylation differences, and pathway enrichment. To determine its biological effects, DNAJC9 was silenced in lung cancer cell lines, and subsequent experiments assessed cellular phenotypes. The downstream PI3K/AKT signaling cascade was examined via western blotting.

Results

Across multiple tumor types, DNAJC9 was markedly upregulated, especially in advanced-stage cases, and higher expression levels predicted worse prognosis. DNAJC9 expression also correlated significantly with immune infiltration, tumor mutation burden (TMB), and microsatellite instability (MSI). Tumor tissues showed substantially lower DNAJC9 methylation than normal tissues. Single-cell analysis detected DNAJC9 expression in multiple immune cell subsets. Knockdown of DNAJC9 in A549 and H1299 lung cancer cells impaired proliferation, migration, and invasion. Functional enrichment analysis then pointed to the PI3K/AKT signaling pathway. Western blotting further confirmed that silencing DNAJC9 reversed the activated PI3K/AKT cascade in these cells, as shown by decreased p-PI3K/PI3K and p-AKT/AKT ratios.

Conclusions

Pan-cancer analyses suggest that DNAJC9 may serve as a diagnostic and prognostic biomarker across cancers. Importantly, its role as an upstream PI3K/AKT activator and its functional validation in lung cancer support DNAJC9 as a potential target for anti-cancer drug discovery in this malignancy.