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INTRODUCTION: The occurrence and progression of lung adenocarcinoma (LUAD) impair T-cell immune responses, causing immune escape and subsequently affecting the efficacy of immunotherapy in patients. Aurora kinase A (AURKA) is upregulated in varying cancers, but its role in LUAD immune escape is elusive. This work attempted to explore molecular mechanisms of AURKA regulation in LUAD immune escape. METHODS: Through bioinformatics analysis, AURKA level in LUAD was evaluated, and potential upstream transcription factors of AURKA were predicted using hTFtarget. ETS variant transcription factor 4 (ETV4) expression in LUAD was analyzed through The Cancer Genome Atlas. Pearson's correlation analysis was then utilized to test the correlation between AURKA and ETV4. Interaction and binding between AURKA and ETV4 were validated through dual-luciferase assay and chromatin immunoprecipitation. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) tested relative mRNA expression of AURKA and ETV4 in LUAD cells, cell counting kit-8 assayed cell viability, and Western blot analysis was conducted to determine the protein level of programmed death-ligand 1 (PD-L1). Coculture of LUAD cells with activated CD8+ T cells was carried out, and an LDH assay was used to assess the cytotoxicity of CD8+ T cells against LUAD cells. Interferon-γ (IFN-γ), interleukin-2 (IL-2), and tumor necrosis factor-α (TNF-α) levels in the coculture system were assessed by enzyme-linked immunosorbent assay (ELISA). Western blot assessed protein levels of JAK2, p-JAK2, STAT3, and p-STAT3. RESULTS: Compared to normal tissues, AURKA and ETV4 were upregulated in tumor tissues, and AURKA presented a negative association with CD8+ T-cell immune infiltration but a positive association with PD-L1. qRT-PCR unveiled significantly upregulated mRNA of AURKA and ETV4 in LUAD cells compared to normal lung epithelial cells. Knockdown of AURKA significantly decreased cell viability and PD-L1 protein level in LUAD cells, enhanced cytotoxicity of CD8+ T cells against LUAD cells and IFN-γ, IL-2, and TNF-α expression, while overexpression of AURKA yielded opposite results. Furthermore, the knockdown of ETV4 could reverse the oncogenic characteristics of cells caused by AURKA overexpression. CONCLUSION: Our study illustrated that ETV4/AURKA axis promoted PD-L1 expression, suppressed CD8+ T-cell activity, and mediated immune escape in LUAD by regulating the JAK2/STAT3 signaling pathway.
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BACKGROUND: The small Ca(2+)-binding protein S100A4 is identified as a metastasis-associated or metastasis-inducing protein in various types of cancer. The goal of this meta-analysis was to evaluate the relationship between S100A4 expression and clinicopathological characteristics and prognosis of patients with pancreatic cancer. METHODS: A comprehensive literature search was carried out in the electronic databases PubMed and Chinese CNKI. Only the studies reporting the correlation between S100A4 expression and clinicopathological characteristics or overall survival (OS) of patients with pancreatic cancer are enrolled. Extracted data was analyzed using the RevMan 5.3 software to calculate the pooled relative risks (95% confidence interval, CI) for statistical analyses. RESULTS: Seven studies including a total of 474 patients were enrolled into this meta-analysis. Negative expression of S100A4 was significantly associated with higher 3-year OS rate (RR = 3.92, 95% CI = 2.24-6.87, P < 0.0001), compared to S100A4-positive cases. Moreover, negative expression of S100A4 was also related to N0 stage for lymph node metastasis (RR = 2.15, 95% CI = 1.60-2.88, P < 0.0001). However, S100A4 expression was not significantly correlated with histological types and distant metastasis status. CONCLUSION: S100A4 expression represents a potential marker for lymph node metastasis of pancreatic cancer and a potential unfavorable factor for prognosis of patients with this disease.