Circ_BBS9 as an early diagnostic biomarker for lung adenocarcinoma: direct interaction with IFIT3 in the modulation of tumor immune microenvironment.

Background: Introduction: Circular RNAs (circRNAs) have been identified as significant contributors to the development and advancement of cancer. The objective of this study was to examine the expression and clinical implications of circRNA circ_BBS9 in lung adenocarcinoma (LUAD), as well as its potential modes of action. Methods: The expression of Circ_BBS9 was examined in tissues and cell lines of LUAD through the utilization of microarray profiling, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot analysis. In this study, we assessed the impact of circ_BBS9 on the proliferation of LUAD cells, as well as its influence on ferroptosis and tumor formation. To analyze these effects, we employed CCK-8 assays and ferroptosis assays. The identification of proteins that interact with Circ_BBS9 was achieved through the utilization of RNA pull-down and mass spectrometry techniques. A putative regulatory network comprising circ_BBS9, miR-7150, and IFIT3 was established using bioinformatics study. The investigation also encompassed the examination of the correlation between the expression of IFIT3 and the invasion of immune cells. Results: Circ_BBS9 was significantly downregulated in LUAD tissues and cell lines. Low circ_BBS9 expression correlated with poor prognosis. Functional experiments showed that circ_BBS9 overexpression inhibited LUAD cell proliferation and promoted ferroptosis in vitro and suppressed tumor growth in vivo. Mechanistically, circ_BBS9 was found to directly interact with IFIT3 and regulate its expression by acting as a sponge for miR-7150. Additionally, IFIT3 expression correlated positively with immune infiltration in LUAD. Conclusion: Circ_BBS9 has been identified as a tumor suppressor in lung adenocarcinoma (LUAD) and holds promise as a diagnostic biomarker. The potential mechanism of action involves the modulation of ferroptosis and the immunological microenvironment through direct interaction with IFIT3 and competitive binding to miR-7150. The aforementioned findings offer new perspectives on the pathophysiology of LUAD and highlight circ_BBS9 as a potentially valuable target for therapeutic interventions.

Upregulation of HLA-II related to LAG-3+CD4+ T cell infiltration is associated with patient outcome in human glioblastoma.

Glioblastoma (GBM) is the most common malignant diffuse glioma of the brain. Although immunotherapy with immune checkpoint inhibitors (ICIs), such as programmed cell death protein (PD)-1/PD ligand-1 inhibitors, has revolutionized the treatment of several cancers, the clinical benefit in GBM patients has been limited. Lymphocyte-activation gene 3 (LAG-3) binding to human leukocyte antigen-II (HLA-II) plays an essential role in triggering CD4+ T cell exhaustion and could interfere with the efficiency of anti-PD-1 treatment; however, the value of LAG-3-HLA-II interactions in ICI immunotherapy for GBM patients has not yet been analyzed. Therefore, we aimed to investigate the expression and regulation of HLA-II in human GBM samples and the correlation with LAG-3+CD4+ T cell infiltration. Human leukocyte antigen-II was highly expressed in GBM and correlated with increased LAG-3+CD4+ T cell infiltration in the stroma. Additionally, HLA-IIHighLAG-3High was associated with worse patient survival. Increased interleukin-10 (IL-10) expression was observed in GBM, which was correlated with high levels of HLA-II and LAG-3+ T cell infiltration in stroma. HLA-IIHighIL-10High GBM associated with LAG-3+ T cells infiltration synergistically showed shorter overall survival in patients. Combined anti-LAG-3 and anti-IL-10 treatment inhibited tumor growth in a mouse brain GL261 tumor model. In vitro, CD68+ macrophages upregulated HLA-II expression in GBM cells through tumor necrosis factor-α (TNF-α). Blocking TNF-α-dependent inflammation inhibited tumor growth in a mouse GBM model. In summary, T cell-tumor cell interactions, such as LAG-3-HLA-II, could confer an immunosuppressive environment in human GBM, leading to poor prognosis in patients. Therefore, targeting the LAG-3-HLA-II interaction could be beneficial in ICI immunotherapy to improve the clinical outcome of GBM patients.

TNF-α-dependent lung inflammation upregulates superoxide dismutase-2 to promote tumor cell proliferation in lung adenocarcinoma.

Manganese superoxide dismutase (SOD-2), an important primary antioxidant enzyme located in mitochondria, plays a critical role in tumor progression. Reportedly, the proinflammatory cytokine, tumor necrosis factor (TNF)-α, can increase SOD-2 expression in a human lung adenocarcinoma cell line in vitro, indicating that TNF-α-mediated inflammation may regulate SOD-2 expression, which may be related to cancer promotion. Using a urethane-induced inflammation-driven lung adenocarcinoma (IDLA) mice model, we investigated whether and how TNF-α-mediated inflammation upregulated SOD-2 expression in lung adenocarcinoma. Our results showed that SOD-2 was mostly expressed on surfactant protein-C+ AT-II cells (alveolar type II cell) and tumor cells in IDLA mice, which were surrounded by CD68+ macrophages. Blocking TNF-α-dependent inflammation downregulated SOD-2 expression in inflamed lung tissues at the protumor stage and also inhibited SOD-2 expression in tumor cells in the IDLA model. In human lung adenocarcinoma, both the number of infiltrating CD68+ macrophages and TNF-α expression correlated positively with SOD-2 expression, which is related to lymph node metastasis and TNM stage. We collected the conditioned medium from lipopolysaccharide-activated phorbol myristate acetate-induced THP1 (M1) cells to stimulate A549 and H1299 cells and observed that THP1-M1 upregulated SOD-2 by secreting TNF-α. Blocking SOD-2 expression significantly inhibited TNF-α-induced cell proliferation in A549 and H1299 cells in vitro. Thus, TNF-α-mediated lung inflammation can upregulate SOD-2 expression in lung adenocarcinoma, and macrophages contribute to SOD-2 upregulation by secreting TNF-α.