The high prevalence of BLCA poses a significant threat to human health and imposes a substantial economic burden. As the tumor progresses to MIBC, the specific survival rate declines to 65–78%(5, 16). necessitating further exploration of the biological mechanisms underlying MIBC development, particularly at the genetic level.
Cuproptosis, a novel copper-dependent cell death modality(8), is regulated by copper ions binding to lipid-acylated components of the tricarboxylic acid cycle (TCA) in mitochondrial respiration, subsequently causing proteotoxic stress and cell death(17, 18). Numerous cuproptosis-related genes have been implicated in cancer progression(19, 20). LncRNAs have emerged as crucial regulators in tumorigenesis by modulating nuclear structure, transcription, mRNA stability, translation, and post-translational modifications(21, 22). It has been reported that cuproptosis-related genes can regulate the stability of lncRNA to promote tumor progression. Exploring the expression patterns of cuproptosis-related lncRNAs may provide us with new ideas and targets for diagnosis, treatment, and prognosis assessment in MIBC.
In this study, we investigated the expression and functions of cuproptosis-related lncRNAs in MIBC and BLCA patients using TCGA and IMvigor210 databases. LASSO Cox regression analysis identified six lncRNAs (FAM13A-AS1, GHRLOS, LINC00456, OPA1-AS1, RAP2C-AS1, and UBE2Q1-AS1) with independent prognostic values for MIBC. A risk model based on these lncRNAs classified MIBC patients into high- and low-risk groups, with the latter exhibiting significantly better survival outcomes. The risk score, an independent prognostic factor, demonstrated good predictive ability for MIBC patients' clinical characteristics.
Cuproptosis-related lncRNAs may act as oncogenes or tumor suppressors. Our study identified 6 cuproptosis-related lncRNAs which had prognostic values. FAM13A-AS1 is an important tumor suppressor factor(23, 24). Previous research found that the upregulation of FAM13A-AS1 inhibits the proliferation, migration, and invasion of breast cancer cell lines by targeting the miRNA-205-3p/DDI2 axis (25). GHRLOS expression levels in colorectal cancer tissues were significantly lower than in matched normal tissues, and decreased GHRLOS expression was significantly associated with the occurrence of lymph node metastasis and distant metastasis in colorectal cancer(26). There are relatively few reports on UBE2Q1-AS1, and studies have shown that UBE2Q1-AS1 may contribute to GC development(27). RAP2C-AS1 is widely expressed in tissues and organs. Studies have indicated that RAP2C-AS1 regulates the occurrence and development of esophageal cancer through the lncRNA-miRNA-mRNA axis(28). Our RT-qPCR results confirmed the low expression of RAP2C-AS1 in tumor tissues, which may imply that it is a tumor suppressor gene.
To elucidate the role of cuproptosis-associated lncRNAs in MIBC, we performed Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses based on differentially expressed genes (DEGs) between distinct risk groups. Unexpectedly, we discovered that numerous cytokine activities, lymphocyte-mediated immune responses, and cytokine-cytokine receptor interactions were enriched. It is plausible to hypothesize that cuproptosis-related lncRNAs are intimately linked to tumor immune regulation, which aligns with prior findings(29, 30). Delving further into the impact of cuproptosis-associated lncRNAs on immune cell infiltration, we observed that various tumor-associated immune cells, including Treg cells, mast cells, and follicular helper T cells, were highly infiltrated in the high-risk group, alongside an enrichment of numerous anti-tumor immune-related signaling molecules. Intriguingly, we identified a substantial presence of immunosuppressive molecules, such as PD-1, IDO1, CTLA4, and PD-L1, in high-risk patients. Previous research has substantiated that elevated PD-L1 expression in MIBC patient tumor tissues enhances the efficacy of anti-PD-L1 therapy(31). I Our findings indicate that high-risk patients in our cohort may exhibit improved responses to anti-PD-L1 immunotherapy. We subsequently validated our hypothesis utilizing the IMvigor210 dataset of BLCA patients undergoing anti-PD-L1 treatment. The constructed predictive model also demonstrated strong prognostic accuracy for anti-PD-L1 treatment response; however, we were surprised to find that patient survival in the high-risk group did not improve following anti-PD-L1 therapy. This may be attributable to the elevated expression of immunosuppressive molecules within the high-risk group, rendering nanotherapeutic anti-immune treatments ineffective (32). These observations suggested that future therapeutic approaches may be directed toward combination therapies(33, 34).
Nonetheless, this study is not without limitations, including the restricted sample size and the absence of methylation level analysis for the candidate lncRNAs. To comprehensively elucidate the regulatory mechanisms of candidate lncRNAs in MIBC, future investigations should encompass an expanded sample size and the acquisition of solid tumor specimens. The identified six lncRNAs may offer valuable insights into the functional mechanisms of cuproptosis-related genes in MIBC patients. Moreover, it is imperative to undertake experimental research to further probe the roles of these lncRNAs.