Tumor Suppressor In Lung Adenocarcinoma Research Articles

Potential Anti-tumor Properties of PDIA4 in Lung Adenocarcinoma.

Given the high frequency and mortality rate of lung cancer, diverse molecular studies have been undertaken to understand cancer pathophysiology and develop novel treatment strategies. The PDIA4 gene, which is involved in protein assembly and endoplasmic reticulum homeostasis, is overexpressed in various lung cancer subtypes. However, its exact function in lung adenocarcinoma (LUAD) remains elusive. The study aimed to investigate the role of PDIA4 in LUAD and explore its role as double-agent gene. PDIA4 expression was knocked out in A549 and LA-4 lung adenoma cells using the Crispr/Cas9 technology. Cell growth, migration, and apoptosis were analyzed in control and PDIA4-deficient cells. PDIA4 deficiency resulted in increased cell growth, enhanced migration capacity, and greater resistance to apoptosis in both A549 and LA-4 lung cancer cells. Mechanistically, up-regulation of oxidative stress followed by NF-[Formula: see text]B activation may contribute to tumor-promoting effects observed upon PDIA4 silencing. PDIA4 appears to function as a tumor suppressor in lung adenocarcinoma, suggesting that PDIA4 may act as a double-agent gene, with roles both on tumor suppression and promotion depending on the context.

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

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. 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. 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. 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.

Ferredoxin 1: a gatekeeper in halting lung adenocarcinoma progression through activation of the GPRIN2 signaling pathway.

Lung adenocarcinoma (LUAD) is a highly lethal form of lung cancer. Despite advancements in treatments, managing LUAD is still challenging due to its aggressive behavior. Recent studies indicate that various molecular pathways, including the dysregulation of ferredoxin 1 (FDX1), play roles in LUAD progression. FDX1, a crucial protein in cellular redox reactions and energy metabolism, has been linked to several cancers. However, its exact role in the development of LUAD is not yet fully understood. We investigated the role of ferredoxin 1 (FDX1) in LUAD progression through analysis of its expression in LUAD tissues and its impact on patient survival. Functional assays were performed to assess the effects of FDX1 overexpression on LUAD cell proliferation, migration, and invasion. A xenograft model was employed to evaluate the tumorigenesis potential of LUAD cells with FDX1 overexpression. Mechanistic insights into FDX1 regulation were gained through depletion experiments targeting the G protein-regulated inducer of neurite outgrowth 2 (GPRIN2)/PI3K signaling pathway. FDX1 expression was down-regulated in LUAD tissues, correlating with shorter patient survival. Overexpression of FDX1 suppressed LUAD cell proliferation, migration, and invasion in vitro, and inhibited tumorigenesis in vivo. Mechanistically, the GPRIN2/PI3K signaling pathway was implicated in FDX1 regulation, as depletion of GPRIN2 reversed the effects of FDX1 overexpression on cellular functions. Our findings highlight FDX1 as a potential tumor suppressor in LUAD, acting through modulation of the GPRIN2/PI3K signaling pathway. These results suggest FDX1 as a promising therapeutic target for LUAD treatment, warranting further investigation into its clinical relevance.

Evaluation of hsa_circ_0000018/let-7f-5p/ FAM96A axis in lung adenocarcinoma progression.

Circular RNAs (circRNAs) are critical regulators of lung adenocarcinoma (LA) progression. Although a molecular marker targeting hsa_circ_0000018 has been developed and used for diagnosing colon cancer, the role of this circRNA in LA progression has not been explored till now. This study aimed to elucidate the role and regulatory mechanisms of hsa_circ_0000018 in LA progression. LA tissues and corresponding adjacent non-tumor tissues were collected from 36 patients to confirm the levels of circRNAs, microRNAs (miRNAs), and messenger RNAs (mRNAs) using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). We also cultured two LA cell lines (A549, PC-9), and the human normal lung epithelial cell line BEAS-2B. Cell function experiments were conducted to assess malignancy in LA cells, including proliferation, migration, and invasion, following forced hsa_circ_0000018 expression. The correlation between hsa_circ_0000018, let-7f-5p, and family with sequence similarity 96 member A (FAM96A) was confirmed by using starBase (miRNA-circRNA interaction database), luciferase assay, and western blotting. Expression of hsa_circ_0000018 and FAM96A was reduced, whereas that of let-7f-5p was upregulated in LA. Cell function assays revealed that upregulation of hsa_circ_0000018 had a suppressive effect on the proliferation, migration, and invasion of LA cells. Additionally, hsa_circ_0000018 sponge binds let-7f-5p, resulting in upregulation of FAM96A expression. Our data reveal hsa_circ_0000018 as a tumor suppressor in LA that targets the let-7f-5p/FAM96A axis. Our findings enrich the known regulatory network of circRNAs in LA.

RNA-binding motif protein 10 inactivates c-Myc by partnering with ribosomal proteins uL18 and uL5.

RNA-binding motif protein 10 (RBM10) is a frequently mutated tumor suppressor in lung adenocarcinoma (LUAD). Yet, it remains unknown whether cancer-derived mutant RBM10 compromises its tumor suppression function and, if so, the molecular insight of the underlying mechanisms. Here, we show that wild-type RBM10 suppresses lung cancer cell growth and proliferation by inactivating c-Myc that is essential for cancer cell survival. RBM10 directly binds to c-Myc and promotes c-Myc's ubiquitin-dependent degradation, while RBM10 knockdown leads to the induction of c-Myc level and activity. This negative action on c-Myc is further boosted by ribosomal proteins (RPs) uL18 (RPL5) and uL5 (RPL11) via their direct binding to RBM10. Cancer-derived mutant RBM10-I316F fails to bind to uL18 and uL5 and to inactivate c-Myc, thus incapable of suppressing tumorigenesis. Our findings uncover RBM10 as a pivotal c-Myc repressor by cooperating with uL18 and uL5 in lung cancer cells, as its failure to do so upon mutation favors tumorigenesis.

The pathological significance and potential mechanism of ARHGEF6 in lung adenocarcinoma

BackgroundEmerging evidences suggest that ARHGEF6 is involved in cancers but the exact significance and underlying mechanism are unclear. This study aimed to elucidate the pathological significance and potential mechanism of ARHGEF6 in lung adenocarcinoma (LUAD). MethodsBioinformatics and experimental methods were used to analyze the expression, the clinical significance, the cellular function and potential mechanisms of ARHGEF6 in LUAD. ResultsARHGEF6 was downregulated in LUAD tumor tissues and correlated negatively with poor prognosis and tumor stemness, positively with the Stromal score, the Immune score and the ESTIMATE score. The expression level of ARHGEF6 was also associated with drug sensitivity, the abundance of immune cells, the expression levels of Immune checkpoint genes and immunotherapy response. Mast cells, T cells and NK cells were the first three cells with the highest expression of ARHGEF6 in LUAD tissues. Overexpression of ARHGEF6 reduced proliferation and migration of LUAD cells and the growth of xenografted tumors, which could be reversed by re-knockdown of ARHGEF6. Results of RNA sequencing revealed that ARHGEF6 overexpression induced significant changes in the expression profile of LUAD cells, and genes encoding uridine 5′-diphosphate-glucuronic acid transferases (UGTs) and extracellular matrix (ECM) components were downregulated. ConclusionsARHGEF6 functions as a tumor suppressor in LUAD and may serve as a new prognostic marker and potential therapeutic target. Regulating tumor microenvironment and immunity, inhibiting the expression of UGTs and ECM components in the cancer cells, and decreasing the stemness of the tumors may among the mechanisms underlying the function of ARHGEF6 in LUAD.

ACADL suppresses PD-L1 expression to prevent cancer immune evasion by targeting Hippo/YAP signaling in lung adenocarcinoma.

Lung cancer is the leading cause of cancer-related death. Cancer immune evasion is a key barrier in the treatment of lung cancer and the development of effective anticancer therapeutics. Long-chain Acyl-CoA dehydrogenase (ACADL), a key enzyme that regulates β-oxidation of long-chain fatty acyl-CoAs, has been found to act as a tumor suppressor in cancers. However, the role of ACADL in lung adenocarcinoma (LUAD) has not been explored. In the current study, we find that ACADL functions as a tumor suppressor in LUAD to inhibit proliferation and enhanced chemotherapeutic drug-induced apoptosis. Interestingly, ACADL prevents tumor immune evasion by suppressing PD-L1 expression in LUAD. ACADL is critical for Hippo/YAP pathway-mediated PD-L1 regulation. Moreover, YAP activation is essential for ACADL suppression of PD-L1 transcription. In addition, ACADL increases the protein stability and kinase activity of LATS kinase to inhibit YAP activation and PD-L1 transcription. Furthermore, we show that ACADL expression is positively correlated with a better OS and FP in LUAD. Our data reveals that ACADL could be a promising target for regulating Hippo/YAP pathway to prevent tumor immune evasion in LUAD.

NLRC3 is a potential prognostic biomarker that is correlated with immune cell infiltration in lung adenocarcinoma

The NLR family CARD domain containing 3 (NLRC3) gene has been reported to have a crucial effect on immunity, inflammation, and tumorigenesis. However, the clinical relevance of NLRC3 in lung adenocarcinoma (LUAD) remains unclear. This study analyzed both RNA sequencing data and corresponding clinical outcomes obtained from public databases to identify (i) NLRC3 as a tumor suppressor in LUAD and (ii) its predictive value for the likelihood of patient responsiveness to immunotherapy. The results showed that NLRC3 expression was reduced in LUAD and was lower in advanced-stage tumors. Additionally, reduced NLRC3 expression was correlated with worse patient prognosis. The protein level of NLRC3 was also observed to have prognostic significance. Moreover, downregulation of NLRC3 was found to suppress the chemotaxis and infiltration of antitumor lymphocyte subpopulations as well as natural killer cells. Mechanistic analysis indicated that NLRC3 may be involved in immune infiltration by regulating chemokines and their receptors in LUAD. Furthermore, NLRC3 functions as a molecular switch in macrophages, whereby it mediates the polarization of M1 macrophages. Patients with high NLRC3 expression were also found to exhibit a more promising response to immunotherapy. In conclusion, NLRC3 could serve as a potential prognostic biomarker for LUAD, help predict the immunotherapeutic response of patients, and guide personalized strategies for the treatment of LUAD.

BDH2 promotes apoptosis and autophagy of lung adenocarcinoma cells via Akt/mTOR pathway.

Cytoprotective autophagy induces tumor cell apoptosis or autophagic programmed cell death. Autophagy and apoptosis are implicated in the pathogenesis of lung cancer, especially lung adenocarcinoma. 3-Hydroxybutyrate dehydrogenase type 2 (BDH2), a rate-limiting catalyzer in the regulation of intracellular iron metabolism and siderophore biogenesis, has been shown to be a tumor suppressor through promotion of cell apoptosis and autophagy. However, the biological role of BDH2 on lung adenocarcinoma cell apoptosis and autophagy remains unclear. Data from Western blot and qRT-PCR showed that BDH2 was down-regulated in lung adenocarcinoma cells (A549, NCI-H1975, PC9) compared to normal human lung cells (BEAS-2B). Functional assays demonstrated that pcDNA-mediated over-expression of BDH2 reduced cell viability of lung adenocarcinoma cells, and repressed the proliferation. Cell apoptosis of lung adenocarcinoma was promoted by BDH2 over-expression with up-regulation of Bax and cleaved caspase-3. Over-expression of BDH2 reduced protein expression of p62 in lung adenocarcinoma cells, enhanced LC3 and Beclin-1. Phosphorylation of AKT and mTOR in lung adenocarcinoma cells were reduced by BDH2 over-expression. In conclusion, BDH2 functioned as a tumor suppressor in lung adenocarcinoma through promotion of Akt/mTOR-mediated cell apoptosis and autophagy.

CAVIN2/SDPR Functioned as a Tumor Suppressor in Lung Adenocarcinoma from Systematic Analysis of Caveolae-Related Genes and Experimental Validation.

Background: Caveolae-Related Genes include caveolins and cavins, which are the main component of the fossa and, play important roles in a variety of physiological and pathological processes. Although increasing evidence indicated that caveolins (CAVs) and cavins (CAVINs) are involved in carcinogenesis and progression, their clinical significance and biological function in lung cancer are still limited. Methods: We investigated the expression of CAVs and CAVINs at transcriptional levels using Oncomine and Gene Expression Profiling Interactive Analysis. The protein and mRNA expression levels of CAVs and CAVINs were determined by the human protein atlas website and our surgically resected samples, respectively. The clinical value of prognostic prediction based on the expression of CAVs and CAVINs was also assessed. cBioPortal, GeneMANIA and STRING were used to analyze the molecular characteristics of CAVs and CAVINs in lung adenocarcinoma (LUAD) comprehensively. Finally, we investigated the effect of CAVIN2/SDPR (serum deprivation protein response) on LUAD cells with biological experiments in vitro. Results: The expression of CAV1/2 and CAVIN1/2/3 were significantly downregulated in LUAD and lung squamous cell carcinoma (LUSC). The patients with high expression of CAV1, CAV2, CAV3, CAVIN1 and CAVIN2/SDPR were tightly correlated with a better prognosis in LUAD, while no statistical significances in LUSC. Further, our results found that CAVIN2/SDPR can be identified as a prognostic biomarker independent of other CAVINs in patients with LUAD. Mechanically, the overexpression of CAVIN2/SDPR inhibited cell proliferation and migration owing to the cell apoptosis induction and cell cycle arrest at S phase in LUAD cells. Conclusions: CAVIN2/SDPR functioned as a tumor suppressor, and was able to serve as prognostic biomarkers in precision medicine of LUAD. Mechanically, overexpression of CAVIN2/SDPR inhibited cell proliferation by inducing cell apoptosis and S phase arrest in LUAD cells.

STK11 mutation affects the killing effect of NK cells to promote the progression of lung adenocarcinoma.

STK11 is a frequently mutated tumor suppressor in lung adenocarcinoma (LUAD). STK11 mutations also lead to dramatic changes in the tumor microenvironment. Studies have shown that strengthening the killing effect of NK cells is vital for effective cancer treatment. Nonetheless, the mechanism of STK11 mutation in modulating the killing effect of NK cells on LUAD cells remains unclear. The expression of STK11, Ki67, and IFN-γ in tumor tissues was evaluated by immunohistochemistry. The contents of T cells, NK cells, and macrophages were analyzed by immunofluorescence assay. The expression of IL2, IL6, and IFN-γ was detected by ELISA. STK11 expression in LUAD cell line was evaluated by qRT-PCR. CCK-8 and colony formation assay were used to measure proliferative ability of LUAD cells and the viability of NK cells. Flow cytometry was utilized to analyze cell apoptosis and NK cell content. Transwell assay was utilized to measure the chemotactic capability of NK cells. In vivo experiments validated the effect of abnormal expression of STK11 on tumor growth. LUAD patients with STK11 mutation had a high tumor proliferative ability. Forced expression of STK11 could substantially constrain the proliferation of LUAD cells and induce cell apoptosis. In addition, STK11 deletion significantly reduced the infiltration level of NK cells and inhibited the viability and chemotactic ability of NK cells as well as their killing effect on LUAD cells. In vivo animal experiment results demonstrated that STK11 deletion significantly reduced NK cell infiltration and promoted LUAD tumor growth. This study revealed the mechanism of STK11 mutation regulating NK cytotoxicity and promoting tumor development, providing scientific basis for the exploration of STK11-related LUAD therapeutic targets and theoretical reference for developing new NK cell-based immunotherapy.

Linc00996 is a favorable prognostic factor in LUAD: Results from bioinformatics analysis and experimental validation.

Background: Linc00996 has been reported in a variety of malignant tumors, but its potential role and significance in lung adenocarcinoma (LUAD) are not fully understood. The authors investigated the expression and biological behavior of Linc00996 in LUAD and elucidated the function of its potential target genes. Materials and methods: The data of Linc00996 expression in cancers were derived from GEPIA. GEO and TCGA datasets were used to identify the differential expression of Linc00996 in LUAD and analyze the respective correlation between different expression levels and LUAD stage and survival prognosis. We further elucidated the potential biological processes and pathways involved with Linc00996 in LAUD by GSEA. ssGSEA was applied to explore the relationship between Linc00996 and immune activity. Finally, the clinical impact of Linc00996 was assessed in 61 patients with LUAD, and the biological functions of Linc00996 were determined by a series of experiments in vitro, such as CCK8, colony formation, migration, and invasion assays. Results: Compared with adjacent normal lung tissues, Linc00996 was significantly downregulated in LUAD, and its expression was negatively correlated with T stage, N stage, and pathological stage. An in vitro study suggested that enhanced Linc00996 expression could inhibit cell proliferation, clonal formation, migration, and invasion in LUAD cell lines. Via GSEA and ssGSEA, we observed that Linc00996 might be connected with immune infiltration in LUAD, and Linc00996 might inhibit tumorigenesis and metastasis by regulating antigen processing and presentation, JAK-STAT3, and cell adhesion molecular signaling pathways. Conclusion: Linc00996 is a novel tumor suppressor in LUAD and may suppress the tumorigenesis and metastasis of LUAD via the tumor-related signaling pathway, such as antigen processing and presentation, JAK-STAT3, and cell adhesion molecular signaling pathways.

MiR-579 Inhibits Lung Adenocarcinoma Cell Proliferation and Metastasis via Binding to CRABP2.

Background Lung cancer is the cancer with the highest morbidity and mortality. Lung adenocarcinoma (LUAD) is a subtype of lung cancer. The aim of this study is to explore the functions of miR-579 and CRABP2 in lung adenocarcinoma. Methods Cell counting kit-8 (CCK-8) and colony formation assays were applied to calculate cell proliferative abilities. Transwell assay was utilized to measure cell invasive ability. Results MiR-579 is low expressed in LUAD tissues and cell lines. MiR-579 inhibits cell viability and invasion of lung adenocarcinoma. Knockdown of CRABP2 inhibits cell proliferation and invasion of Calu-3 cells. MiR-579 suppresses cell proliferation and invasion by regulating CRABP2 in Calu-3 cells. Conclusion Our study reveals that miR-579 acts as a tumor suppressor in LUAD and miR-579 can target and regulate the expression of CRABP2 to mediate cell proliferation and invasion. This study indicates that miR-579 has a potential to be a candidate biomarker for the treatment of LUAD.

LINC02535/miR-30a-5p/GALNT3 axis contributes to lung adenocarcinoma progression via the NF- κ B signaling pathway

ABSTRACT Long non-coding RNAs (LncRNA) play important roles in multiple types of cancers. We addressed the role of LINC02535 by regulating the miR-30a-5p /GalNAc Transferase 3 (GALNT3) axis to promote the proliferation, migration, and invasion in lung adenocarcinoma (LUAD) cells. The Cancer Genome Atlas (TCGA) database screened differentially expressed lncRNAs. Quantitative real-time PCR analysis (qRT-PCR) confirmed that LINC02535 is highly expressed in LUAD tissues and cells. In vitro experiments showed that LINC02535 promotes the proliferation, migration, and invasion of LUAD cells. A xenograft mouse model was used to show that LINC02535 promotes tumor growth in vivo. RNA immunoprecipitation (RIP) and Dual-luciferase reporter assay results confirmed that LINC02535 targets miR-30a-5p. The Vicia villosa lectin (VVA) pull-down assay indicated that MUC1 is the glycosylation target of GALNT3, and western blot verified that NF-κB is the downstream signaling pathway of MUC1. We found that LINC02535 was increased in LUAD tissues and cells, and LINC02535 was correlated with the poor prognosis of LUAD patients. miR-30a-5p acts as a tumor suppressor in LUAD by targeting GALNT3. We also demonstrated that LINC02535 might function as the sponge of miR-30a-5p to up-regulate GALNT3, and consequently promote the proliferation and metastasis of LUAD. LINC02535 acts as a competing endogenous RNA (ceRNA) to interact with miR-30a-5p, thereby upregulating the expression of GALNT3, enhancing the function of MUC1, and activating the NF-κB signaling pathway, promoting the malignant progression of LUAD cells. Abbreviations: LncRNA:long non-coding RNA; LUAD: lung adenocarcinoma; TCGA: The Cancer Genome Atlas; GALNT3: GalNAc Transferase 3; qRT-PCR: quantitative real-time PCR analysis; RIP: RNA immunoprecipitation; SPF: specific pathogen-free; VVA: Vicia villosa lectin; ceRNA: competing endogenous RNA; MiRNAs: microRNAs; FBS: fetal bovine serum; PBS: Phosphate buffered saline; CCK-8: Cell Counting Kit-8; NSCLC: non-small cell lung cancer; OC: ovarian cancer; HCC: hepatocellular carcinoma.

Abstract 2113: Suppression of macrophage migration inhibitory factor (MIF) impairs tumor growth and overcomes immunotherapy resistance in KEAP1-deficient NSCLC tumors

Abstract Background: KEAP1, which regulates the degradation of the antioxidant transcription factor NRF2, is the third most commonly mutated tumor suppressor in lung adenocarcinoma (LUAD). Recent reports have provided clinical evidence that mutations in STK11/LKB1 and KEAP1 are strongly associated with immune checkpoint blockade resistance in LUAD, particularly those harboring KRAS mutations. Nevertheless, the specific mechanisms by which loss of KEAP1 impacts anti-tumor immunity in KRAS mutant tumors remains to be determined. Methods: KRAS-mutant (K) and LKB1 (KL), and/or KEAP1-deficient (KK and KLK) murine tumor models were profiled using single-cell RNA sequencing (scRNA-seq) and multiplex staining, and response to anti-PD1 treatment was assessed. Clinical samples from the MD Anderson ICON study (a cohort of 148 resected tumors from early-stage lung cancer patients) and TCGA lung cohorts were used to validate pre-clinical findings. Results: While K tumors were sensitive to anti-PD1 treatment, KEAP1-deficient isogenic tumors (KK; KLK) were refractory. KEAP1-deficient tumors were found to exhibit low immune cell infiltration and an enrichment of cancer associated fibroblasts (CAFs) and endothelial cells. scRNA-seq analysis indicated that KEAP1-deficient tumors had reduced T cell infiltration, in particular, CD8 and NK T cells, decreased B cell populations, and a marked change in M2 macrophage polarization as compared to KEAP1-proficient tumors. Multiplex analysis of CD3 and F4/80 markers confirmed these findings. In the TCGA lung cancer cohort, CD8B expression was dramatically decreased while MIF (macrophage migration inhibitory factor) was upregulated in KK tumors as compared to K LUAD tumors, and expression of KEAP1 inversely correlated with CD163, ARG2 and IL10, which are mainly secreted by macrophages. KEAP1-deficient pre-clinical tumor models showed a significant upregulation of MIF expression and secretion. CRISPR-Cas9 deletion of MIF dramatically impaired in vivo tumor growth, and enhanced T cell cytotoxic effects, anti-tumor immune response and anti-PD1 treatment in KK and KLK tumor models. Conclusions: These findings indicate that loss of KEAP1, alone or in combination with STK11/LKB1 alterations, contributes to an immunosuppressed tumor immune microenvironment. These changes appear to be mediated at least in part through MIF upregulation, providing a potential therapeutic strategy for overcoming KEAP1-dependent resistance to immunotherapy. Citation Format: Ana Galan-Cobo, Yu Qian, Fuduan Peng, Daniel James McGrail, Sonia Patel, Fahao Zhang, Xiang Zhang, Ferdinandos Skoulidis, Edwin Parra, Minghao Dang, Saxon Rodriguez, Alexandre Reuben, Ignacio Wistuba, Linghua Wang, John Victor Heymach. Suppression of macrophage migration inhibitory factor (MIF) impairs tumor growth and overcomes immunotherapy resistance in KEAP1-deficient NSCLC tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2113.

POU4F3 Acts as a Tumor Suppressor in Lung Adenocarcinoma via the Endoplasmic Reticulum Stress Signaling Pathway

Lung cancer is the most common malignancy worldwide, and LUAD is the primary type of lung cancer. Recently, the POU transcription factor family has been associated with the development of multicancer, especially lung cancer. However, the relationship between POU domain class Ⅳ transcription factor Ⅲ (POU4F3) and lung cancer remains unknown. We detected the expression of POU4F3 in human LUAD and adjacent tissues with immunohistochemical staining, and we found that POU4F3 was expressed less in LUAD tissues compared with adjacent tissues. Patients with higher POU4F3 expression have more prolonged overall survival. We then constructed SPCA1 and A549 cells with stable overexpression or inhibition of POU4F3. We found that overexpressed POU4F3 suppressed LUAD cell proliferation in vitro and in vivo, according to CCK-8, colony formation, and xenograft assays. LUAD cell apoptosis was suppressed by POU4F3 overexpression based on Flow cytometry. The downregulation of POU4F3 yielded the opposite patterns. Next, we explored the possible mechanisms through which POU4F3 promoted the apoptosis of LUAD cells. Western blotting suggested that overexpression of POU4F3 significantly increased protein expression levels of the PERK/eIF2α/ATF4/CHOP and IRE1α/XBP1s pathways of ERS, while POU4F3 absence reversed the expressions of the above essential proteins in ERS pathways in SPCA1 and A549 cells. However, we found that PERK inhibitor but not IRE1 inhibitor can reverse the effect of POU4F3 overexpression on apoptosis. This study indicated that POU4F3 may work as a tumor suppressor in LUAD via regulating the PERK/eIF2α/ATF4/CHOP pathway. We made it possible to develop POU4F3 as a diagnostic, therapeutic, and prognostic target of LUAD.

CCDC65, a Gene Knockout that leads to Early Death of Mice, acts as a potentially Novel Tumor Suppressor in Lung Adenocarcinoma.

CCDC65 is a member of the coiled-coil domain-containing protein family and was only reported in gastric cancer by our group. We first observed that it is downregulated in lung adenocarcinoma based on the TCGA database. Reduced CCDC65 protein was shown as an unfavorable factor promoting the clinical progression in lung adenocarcinoma. Subsequently, CCDC65-/- mice were found possibly dead of hydrocephalus. Compared with the CCDC65+/+ mice, the downregulation of CCDC65 in CCDC65+/- mice significantly increased the formation ability of lung cancer induced by urethane. In the subsequent investigation, we observed that CCDC65 functions as a tumor suppressor repressing cell proliferation in vitro and in vivo. Molecular mechanism showed that CCDC65 recruited E3 ubiquitin ligase FBXW7 to induce the ubiquitination degradation of c-Myc, an oncogenic transcription factor in tumors, and reduced c-Myc binding to ENO1 promoter, which suppressed the transcription of ENO1. In addition, CCDC65 also recruited FBXW7 to degrade ENO1 protein by ubiquitinated modulation. The downregulated ENO1 further reduced the phosphorylation activation of AKT1, which thus inactivated the cell cycle signal. Our data demonstrated that CCDC65 is a potential tumor suppressor by recruiting FBWX7 to suppress c-Myc/ENO1-induced cell cycle signal in lung adenocarcinoma.

HSD17B6 downregulation predicts poor prognosis and drives tumor progression via activating Akt signaling pathway in lung adenocarcinoma

Lung adenocarcinoma is one of the most frequent tumor subtypes, involving changes in a variety of oncogenes and tumor suppressor genes. Hydroxysteroid 17-Beta Dehydrogenase 6 (HSD17B6) could synthetize dihydrotestosterone, abnormal levels of which are associated with progression of multiple tumors. Previously, we showed that HSD17B6 inhibits malignant progression of hepatocellular carcinoma. However, the mechanisms underlying inhibiting tumor development by HSD17B6 are not clear. Moreover, its role in lung adenocarcinoma (LUAD) is yet unknown. Here, we investigated its expression profile and biological functions in LUAD. Analysis of data from the LUAD datasets of TCGA, CPTAC, Oncomine, and GEO revealed that HSD17B6 mRNA and protein expression was frequently lower in LUAD than in non-neoplastic lung tissues, and its low expression correlated significantly with advanced tumor stage, large tumor size, poor tumor differentiation, high tumor grade, smoking, and poor prognosis in LUAD. In addition, its expression was negatively regulated by miR-31-5p in LUAD. HSD17B6 suppressed LUAD cell proliferation, migration, invasion, epithelial–mesenchymal transition (EMT), and radioresistance. Furthermore, HSD17B6 overexpression in LUAD cell lines enhanced PTEN expression and inhibited AKT phosphorylation, inactivating downstream oncogenes like GSK3β, β-catenin, and Cyclin-D independent of dihydrotestosterone, revealing an underlying antitumor mechanism of HSD17B6 in LUAD. Our findings indicate that HSD17B6 may function as a tumor suppressor in LUAD and could be a promising prognostic indicator for LUAD patients, especially for those receiving radiotherapy.

1184P Necroptosis establishes an inflammatory tumor immune microenvironment acting as tumor suppressor in lung adenocarcinoma

Receptor-Interacting Serin/Threonin-Protein Kinase 3 (RIPK3) mediates necroptosis, a programmed form of cell death, which elicits the release of intracellular contents (DAMPs) and cytokines. These substances attract and activate anti-tumoral immune cells, rendering necroptosis highly immunogenic. In lung adenocarcinomas (LUAD), RIPK3 is a tumor suppressive aberrational target, which has been shown to induce immune suppression in the tumor microenvironment.

LncRNA GAS6-AS1 inhibits progression and glucose metabolism reprogramming in LUAD via repressing E2F1-mediated transcription of GLUT1

Glucose metabolism reprogramming is one of the hallmarks of cancer cells, although functional and regulatory mechanisms of long noncoding RNA (lncRNA) in the contribution of glucose metabolism in lung adenocarcinoma (LUAD) remain incompletely understood. The aim of this study was to uncover the role of GAS6-AS1 in the regulation of progression and glucose metabolism in LUAD. We discovered that overexpression of GAS6-AS1 suppressed tumor progression of LUAD both in vitro and in vivo. Metabolism-related assays revealed that GAS6-AS1 inhibited glucose metabolism reprogramming. Mechanically, GAS6-AS1 was found to repress the expression of glucose transporter GLUT1, a key regulator of glucose metabolism. Ectopic expression of GLUT1 restored the inhibition effect of GAS6-AS1 on cancer progression and glucose metabolism reprogramming. Further investigation identified that GAS6-AS1 directly interacted with transcription factor E2F1 and suppressed E2F1-mediated transcription of GLUT1, and GAS6-AS1 was downregulated in LUAD tissues and correlated with clinicopathological characteristics and survival of patients. Taken together, our results identified GAS6-AS1 as a novel tumor suppressor in LUAD and unraveled its underlying molecular mechanism in reprogramming glucose metabolism. GAS6-AS1 potentially may serve as a prognostic marker and therapeutic target in LUAD.