Lactate dehydrogenase B as a metabolism-related marker for immunotherapy in head and neck squamous cell carcinoma.

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is one of the most common malignancies. Lactate dehydrogenase family genes (LDHs) play a critical role in tumor metabolism, but their functions in HNSCC have not been investigated thoroughly. Thus, we aimed to explore the value of LDHs in HNSCC.

METHODS

The association between LDHs expression and mutations, methylation, copy number variations (CNVs), alternative splicing (AS) and competing endogenous RNA (ceRNA) was investigated in The Cancer Genome Atlas (TCGA). The expression level of LDHs in OSCC tissues and adjacent normal tissues was verified by qPCR. Algorithms, such as ssGSEA, ESTIMATE, xCell and TIDE were utilized to analyze the characteristics of immune infiltration. Pathway alternations were enriched by GO, GSEA and KEGG analysis. The Mantel test was employed to elucidate the correlation between metabolism and the tumor microenvironment (TME). Subsequently, MTT and colony formation assays were utilized to assess the impact of LDHB knockdown on cellular proliferation. Additionally, ATP and lactate assays were performed to examine metabolic alterations. Co-culture experiments further investigated the effect of LDHB knockdown on T cell differentiation.

RESULTS

LDHs were completely analyzed in multiple databases, among which LDHB was differentially expressed in HNSCC and significantly associated with prognosis. Low LDHB expression had better clinicopathological characteristics. Downregulated LDHB expression was associated with enhanced immune cell infiltration and could influence tumor metabolism. Despite having worse cytotoxic T lymphocyte dysfunction, the LDHB group was predicted to respond more favorably to immune checkpoint inhibitors (ICIs) therapy. Moreover, the correlation between metabolism and TME was depicted. In vitro, LDHB knockdown resulted in inhibited cell proliferation, increased lactate levels and decreased ATP levels, while promoted the Th1 differentiation of T cells.

CONCLUSIONS

Our study provided a comprehensive analysis of the LDHs and illustrated low LDHB expression could inhibit tumor cell proliferation and ATP production by influencing metabolism, with improved immune cell infiltration and better response to immunotherapy.