Tumor Progression In Lung Adenocarcinoma Research Articles

Circ_100549 promotes tumor progression in lung adenocarcinoma through upregulation of BIRC6.

Lung adenocarcinoma (LUAD) is a subtype of lung cancer with high incidence and mortality globally. Emerging evidence suggests that circular RNAs (circRNAs) exert critical functions in human cancers, including LUAD. CircRNA_100549 (circ_100549) has been reported to be significantly upregulated in non-small cell lung cancer (NSCLC) samples, while its role in modulating LUAD progression remains to be explored. The current study aims at investigating the functional roles of circ_100549 in LUAD and its downstream molecular mechanism. First, we found that the expression of circ_100549 was higher in LUAD cell lines. Loss-of-function assays verified that depletion of circ_100549 repressed LUAD cell proliferation but accelerated cell apoptosis. Furthermore, in vivo experiments demonstrated that silencing of circ_100549 suppressed tumor growth. Subsequently, based on database analysis, we carried out a series of experiments to explore the mechanisms and effects of circ_100549 underlying LUAD progression, including RNA-binding protein immunoprecipitation (RIP), RNA/DNA pull-down, luciferase reporter, and chromatin immunoprecipitation (ChIP) assays. The results indicated that circ_100549 serves as a ceRNA by sponging miR-95-5p to upregulate BPTF expression, thus upregulating BIRC6 expression at a transcriptional level in LUAD. In summary, our study demonstrated that circ_100549 facilitates LUAD progression by upregulating BIRC6 expression.

Identification and validation of LINC01322 as a potential prognostic biomarker and oncogene promoting tumor progression in lung adenocarcinoma

Our study identified a novel long noncoding RNA, LINC01322, that acts as an oncogene in lung adenocarcinoma progression. Cytoplasmic and nuclear RNA purification assays indicated that LINC01322 was localized in the cytoplasm and nucleus. Gene set enrichment analysis revealed the involvement of LINC01322 in the regulation of cell proliferation, migration, and the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway. LINC01322 may promote lung adenocarcinoma proliferation and migration through the Janus kinase/signal transducer and activator of transcription signaling pathway. In vitro experiments demonstrated that the knockdown of LINC01322 significantly suppressed lung adenocarcinoma cell proliferation, migration, and activation of the Janus kinase 2/signal transducer and activator of transcription 3 signaling pathway, whereas overexpression had the opposite effects. Inhibition of the Janus kinase 2/signal transducer and activator of transcription 3 pathway activity partially reversed the enhancement of cell proliferation and migration caused by LINC01322 overexpression. In vivo experiments further verified the oncogene role of LINC01322. Altogether, our findings suggest that LINC01322 promotes lung adenocarcinoma progression by activating the Janus kinase 2/signal transducer and activator of transcription 3 signaling pathway and that it could be a therapeutic target.

DLX1 acts as a novel prognostic biomarker involved in immune cell infiltration and tumor progression in lung adenocarcinoma.

The biological function of distal-less homeobox 1 (DLX1) in lung adenocarcinoma (LUAD) remains unclear, despite a growing body of evidence that DLX1 is involved in the initiation and progression of various tumors. This study explored and confirmed the prognostic and immunologic roles of DLX1 in LUAD via bioinformatic analysis and cellular functional validation. MethSurv was used to analyze the DNA methylation levels of DLX1 and the prognostic value of CpG islands. DLX1 mutation rates and prognoses between patients with and without the mutated DLX1 gene were analyzed by cBioPortal. Finally, cellular functional assays were used to investigate the effect of DLX1 on LUAD cells. Our results showed that DLX1 mRNA expression was significantly upregulated in LUAD. High DLX1 expression or promoter methylation was associated with worse prognosis, which confirmed DLX1 as an independent prognostic factor in LUAD. The level of multiple immune cell infiltration was significantly associated with DLX1 expression. Genes in the high DLX1 expression group were mainly enriched in cell cycle checkpoint, DNA replication, DNA repair, Fceri-mediated MAPK activation, TP53 activity regulation, and MET activation of PTK2-regulated signaling pathways. Cellular functional assays showed that the knockdown of DLX1 inhibited the proliferation, migration, and invasion of LUAD cells. Our study identified DLX1 as a potential diagnostic and prognostic biomarker, and a promising therapeutic target in LUAD.

Unlocking the role of EIF5A: A potential diagnostic marker regulating the cell cycle and showing negative correlation with immune infiltration in lung adenocarcinoma

BackgroundDespite EIF5A upregulation related to tumor progression in LUAD (lung adenocarcinoma), the underlying mechanisms remain elusive. In addition, there are few comprehensive analyses of EIF5A in LUAD. MethodsWe investigated the EIF5A expression level in LUAD patients using data from the TCGA and GEO databases. We employed qRT-PCR and western blot to verify EIF5A expression in cell lines, while immunohistochemistry was utilized for clinical sample analysis. We analyzed EIF5A expression in tumor-infiltrating immune cells using the TISCH database and assessed its association with immune infiltration in LUAD using the “ESTIMATE” R package. Bioinformatics approaches were developed to discover the EIF5A-related genes and explore EIF5A potential mechanisms in LUAD. Proliferation ability was verified through CCK-8, clone formation, and EdU assays, while flow cytometry assessed apoptosis and cell cycle. Western blot was used to detect the expression of pathway-related proteins. ResultsEIF5A was significantly upregulated in LUAD. Moreover, we constructed a MAZ-hsa-miR-424-3p-EIF5A transcriptional network. We explored the potential mechanism of EIF5A in LUAD and further investigated the cAMP signaling pathway and the cell cycle. Finally, we proved that EIF5A silencing induced G1/S Cell Cycle arrest, promoted apoptosis, and inhibited proliferation via the cAMP/PKA/CREB signaling pathway. ConclusionEIF5A serves as a prognostic biomarker with a negative correlation to immune infiltrates in LUAD. It regulated the cell cycle in LUAD by inhibiting the cAMP/PKA/CREB signaling pathway.

Prostaglandin 15d-PGJ2 inhibits proliferation of lung adenocarcinoma cells by inducing ROS production and activation of apoptosis via sirtuin-1

Lung adenocarcinoma (LUADC) belongs to the most prevalent and lethal cancer types. As 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) displays anti-oxidative, -inflammatory, and -cancer properties, we investigated whether this cyclopentenone PG, a stable degradation end-product of cyclooxygenase-generated PGD2, exerts beneficial effects in three LUADC cell lines (A549, H1299, H23). We here report that 15d-PGJ2 had substantial cytotoxic effects in all three LUADC cell lines by promoting early apoptosis and inhibiting the cell cycle, proliferation, and migration. As indicators of cell malignancy, scratch closure and colony formation were significantly inhibited by 15d-PGJ2. 15d-PGJ2 induced generation of ROS and subsequent activation of MAPKs. Expression of Nrf-2, a well-known tumor driver, was markedly diminished by 15d-PGJ2 treatment. Although PPARγ, DP1, and DP2 are expressed in LUADC cells, blocking these receptors with specific inhibitors (SR16832 and BW245C) did not reverse 15d-PGJ2-mediated cytotoxicity, suggesting receptor-independent effects. 15d-PGJ2 decreased SIRT1 expression in LUADC cells and the knockdown of SIRT1 diminished the cytotoxic effects of 15d-PGJ2. Importantly, 15d-PGJ2 significantly reduced tumor growth using the chorioallantoic membrane (CAM) assay. The structural analog of 15d- PGJ2, 9,10-dihydro-15d-PGJ2 (lacking the α,β-unsaturated ketone structural element), did not show any toxic effects in LUADC cells. Altogether, our findings suggest that 15d-PGJ2 led to significantly reduced tumor growth and cell proliferation in three LUADC cell lines. The CAM assay results suggest that 15d-PGJ2 is a suitable endogenous compound to interfere with LUADC tumor progression. We show that SIRT1 modulates the effects of 15d-PGJ2 and may be used as a therapeutic target for LUADC.

Upregulation of M6A Reader HNRNPA2B1 Associated with Poor Prognosis and Tumor Progression in Lung Adenocarcinoma.

Lung cancer is the most prevalent malignancy worldwide, and lung adenocarcinoma (LUAD) accounts for a substantial proportion of all cases. N6-methyladenosine (m6A) is the most frequent post-transcriptional modification in mRNAs that also plays a role in cancer development. Heterogeneous nuclear ribonucleoprotein A2/B1 (HNRNPA2B1) is a reader of m6A modification, which can affect tumor invasion, migration, and proliferation. The purpose of this study was to explore the prognostic factors of LUAD based on m6A through bioinformatics analysis. The expression levels and prognostic significance of HNRNPA2B1 in LUAD were analyzed on the basis of data extracted from the UALCAN, GEPIA, NCBI-GEO, Human Protein Atlas, STRING, miRDB, TargetScan, PROMO, Starbase, UCSC Xena browser, TIMER, and TISIDB databases. HNRNPA2B1 protein and mRNA levels in several LUAD cell lines were detected by western blotting and qRT-PCR. CCK8, wound-healing and transwell assays were performed to evaluate the proliferation, invasion, and migration abilities of LUAD cells. HNRNPA2B1 mRNA was found to be significantly overexpressed in LUAD tissues, and its high levels correlated with poor OS and DFS. The genes co-expressed with HNRNPA2B1 were related to mRNA production, cell cycle, and histone binding. To determine the mechanistic basis of HNRNPA2B1 in LUAD, we next predicted the microRNAs and transcription factors that were directly associated with HNRNPA2B1, as well as copy number changes. In addition, it was found that HNRNPA2B1 expression was significantly related to CD4+ T cells, neutrophils, lymphocytes, immunomodulators, and chemokines. Besides, knocking down HNRNPA2B1 in the LUAD cells led to a significant reduction in their proliferation, invasion, and migration rates in vitro. Elevated HNRNPA2B1 is a risk factor in LUAD and portends a poor prognosis.

Osimertinib resistance prognostic gene signature: STRIP2 is associated with immune infiltration and tumor progression in lung adenocarcinoma.

Although the use of osimertinib can significantly improve the survival time of lung adenocarcinoma (LUAD) patients with epithelial growth factor receptor mutation, eventually drug resistance will limit the survival benefit of most patients. This study aimed to develop a novel prognostic predictive signature based on genes associated with osimertinib resistance. The differentially expressed genes (DEGs) associated with osimertinib resistance in LUAD were screened from Gene Expression Omnibus datasets and The Cancer Genome Atlas datasets. Multivariate cox regression was used to establish a prognostic signature, and then a nomogram was developed to predict the survival probability of LUAD patients. We used ROC curve and DCA curve to evaluate its clinical prediction accuracy and net benefit.In addition, the differentially expressed genes significantly associated with prognosis were selected for immune infiltration analysis and drug sensitivity analysis, and their roles in the progression of lung adenocarcinoma were verified by in vitro experiments. Our evaluation results indicated that the new nomogram had higher clinical prediction accuracy and net benefit value than the TN nomogram. Further analysis showed that patients with low STRIP2 expression had a higher level of immune response, and may be more likely to benefit from immune checkpoint inhibitors and conventional antitumor drugs. This may help to select more precise and appropriate therapy for LUAD patients with osimertinib resistance. Furthermore, in vitro experiments showed that STRIP2 promoted the LUAD cells proliferation, migration and invasion. This further demonstrates the importance of this gene signature for prognostic prediction. We developed a reliable prognostic model based on DEGs associated with osimertinib resistance and screened for biomarker that can predict the immune response in LUAD patients, which may help in the selection of treatment regimens after osimertinib resistance.

Identification and validation of tumor microenvironment-related signature for predicting prognosis and immunotherapy response in patients with lung adenocarcinoma

Mounting evidence has found that tumor microenvironment (TME) plays an important role in the tumor progression of lung adenocarcinoma (LUAD). However, the roles of tumor microenvironment-related genes in immunotherapy and clinical outcomes remain unclear. In this study, 6 TME-related genes (PLK1, LDHA, FURIN, FSCN1, RAB27B, and MS4A1) were identified to construct the prognostic model. The established risk scores were able to predict outcomes at 1, 3, and 5 years with greater accuracy than previously known models. Moreover, the risk score was closely associated with immune cell infiltration and the immunoregulatory genes including T cell exhaustion markers. In conclusion, the TME risk score can function as an independent prognostic biomarker and a predictor for evaluating immunotherapy response in LUAD patients, which provides recommendations for improving patients’ response to immunotherapy and promoting personalized tumor immunotherapy in the future.

MRPL12 Acts as A Novel Prognostic Biomarker Involved in Immune Cell Infiltration and Tumor Progression of Lung Adenocarcinoma.

Mitochondrial ribosomal protein L7/L12 (MRPL12) is a member of the mitochondrial ribosomal proteins (MRPs). However, the biological function of MRPL12 in lung adenocarcinoma (LUAD) remains unclear. The expression and prognostic value of MRPL12 in LUAD were systematically analyzed using UALCAN, TIMER, HPA, Kaplan-Meier plotter, and GEPIA databases. The relationship between MRPL12 and immune infiltrates was investigated using TIMER and TISIDB databases. The clinical significance of MRPL12 in LUAD patients was validated using a tissue microarray (TMA). Cellular functional experiments were carried out to examine the influences of MRPL12 knockdown on cell proliferation, migration, and invasion. MRPL12 was significantly upregulated in LUAD samples, and high MRPL12 expression was correlated with worse prognosis. MRPL12 expression was markedly associated with immunomodulators, chemokines, and infiltration levels of multiple immune cells. Furthermore, TMA results confirm the upregulation of MRPL12 expression in LUAD, and MRPL12 was identified as an independent prognostic factor in LUAD patients. MRPL12 knockdown inhibited proliferation, migration, and invasion of LUAD cells. These data indicate that MRPL12 is a prognostic biomarker and correlated with immune infiltrates in LUAD. Therefore, MRPL12 shows potential as a therapeutic target for LUAD.

Somatic A-to-I RNA-edited RHOA isoform 2 specific-R176G mutation promotes tumor progression in lung adenocarcinoma.

Adenosine-to-inosine (A-to-I) RNA editing is the most common posttranscriptional editing to create somatic mutations and increase proteomic diversity. However, the functions of the edited mutations are largely underexplored. To identify novel targets in lung adenocarcinoma (LUAD), we conducted a genome-wide somatic A-to-I RNA editing analysis of 23 paired adjacent normal and LUAD transcriptomes and identified 26,280 events, including known nonsynonymous AZIN1-S367G and novel RHOAiso2 (RHOA isoform 2)-R176G, tubulin gamma complex associated protein 2(TUBGCP2)-N211S, and RBMXL1-I40 M mutations. We validated the edited mutations in silico in multiple databases and in newly collected LUAD tissue pairs with the SEQUENOM MassARRAY® and TaqMan PCR Systems. We selected RHOAiso2-R176G due to its significant level, isoform-specificity, and being the most common somatic edited nonsynonymous mutation of RHOAiso2 to investigate its roles in LUAD tumorigenesis. RHOAiso2 is a ubiquitous but low-expression alternative spliced isoform received a unique Alu-rich exon at the 3' RHOA mRNA to become an editing RNA target, leading to somatic hypermutation and protein diversity. Interestingly, LUAD patients harboring the RHOAiso2-R176G mutation were associated with aberrant RHOA functions, cancer cell proliferation and migration, and poor clinical outcomes in transcriptome analysis. Mechanistically, RHOAiso2-R176G mutation-expressing LUAD cells potentiate RHOA-guanosine triphosphate (GTP) activity to phosphorylate ROCK1/2 effectors and enhance cell proliferation and migration in vitro and increase tumor growth in xenograft and systemic metastasis models in vivo. Taken together, the RHOAiso2-R176G mutation is a common somatic A-to-I edited mutation of the hypermutated RHOA isoform 2. It is an oncogenic and isoform-specific theranostic target that activates RHOA-GTP/p-ROCK1/2 signaling to promote tumor progression.

LINC00491 Facilitates Tumor Progression of Lung Adenocarcinoma via Wnt/β-Catenin-Signaling Pathway by Regulating MTSS1 Ubiquitination

Background: Long non-coding RNAs have been reported to be involved in tumorigenesis and progression through different regulatory mechanisms. It has been reported that aberrantly expressed long non-coding RNA LINC00491 promotes malignancy in multiple tumors, while the role of LINC00491 in lung adenocarcinoma (LUAD) is little reported and the mechanism for regulating tumor progression has not been elucidated. Methods: RNA sequencing and the TCGA database were combined to screen differentially expressed lncRNAs that facilitate tumor progression. The expression level of LINC00491 was examined in LUAD clinical samples and in cell lines using RT-qPCR. In vitro experiments including colony formation assay, EdU assay, cell migration and invasion assay and wound healing assay, and in vivo experiments including xenografting subcutaneous tumors and lung metastasis models were performed to investigate the function of LINC00491 in LUAD tumor progressions. RNA pull-down, mass spectrometry, RIP assays and truncation experiments were carried out to explore the proteins binding to LINC00491 and the specific interactions between the RNA-protein complex. Results: Our results showed that LINC0491 was significantly upregulated in LUAD and positively correlated with poor survival. High LINC00491 expression promoted proliferation, migration and invasion, and resulted in a high metastatic burden in LUAD. Using pull-down assay and mass spectrometry, MTSS1 was found binding to LINC00491, and the conducted experiments verified the direct interaction between LINC00491 and MTSS1. Meanwhile, LINC00491 was found to regulate MTSS1 degradation by promoting the MTSS1 ubiquitination level and then activating the Wnt/β-catenin-signaling pathway. LINC00491/MTSS1/β-catenin may act as a complex to facilitate tumor progression. Conclusions: In summary, our results found a novel mechanism in which LINC00491 directly interacts with MTSS1 by affecting its ubiquitination modification to promote LUAD proliferation, migration and invasion, then activating the Wnt/β-catenin-signaling pathway, demonstrating its significant role in tumor progression and suggesting that the LINC00491/MTSS1/Wnt/β-catenin-signaling pathway could serve as a potential therapeutic target for lung adenocarcinoma in the future.

A prognostic signature model for unveiling tumor progression in lung adenocarcinoma.

A more accurate prognosis is important for clinical treatment of lung adenocarcinoma. However, due to the limitation of sample and technical bias, most prognostic signatures lacked reproducibility, and few were applied to clinical practice. In addition, understanding the molecular driving mechanism is indispensable for developing more promising therapies for lung adenocarcinoma. Here, we built an unbiased prognostic significance model to perform an integrative analysis, including differentially expressed genes and clinical data with lung adenocarcinoma patients from TCGA. Multivariable Cox proportional hazards model with the Lasso penalty and 10-fold cross-validate were used to identify the best gene signature. We generated a 17-gene signature for prognostic risk prediction based on the overall survival time of lung adenocarcinoma patients. To further test the model's predictive ability, we have applied an independent GEO database to verify the predictive ability of prognostic signature. The model can more objectively describe several biological processes related to tumors and reveal important molecular mechanisms in tumor development by GO and KEGG analysis. Furthermore, differential expression analysis by GSEA revealed that tumor microenvironments such as ER stress, exosome, and immune microenvironment were enriched. Using single-cell RNA sequence technology, we found that risk score was positively correlated with lung adenocarcinoma marker genes and copy number variation but negatively correlated with lung epithelial marker genes. High-risk cell populations with the model had stronger cancer stemness and tumor-related pathway activation. As we expected, the risk score was in accordance with the malignancy of each cluster from tumor progression. In conclusion, the risking model established in this study is more reliable than others in evaluating the prognosis of LUAD patients.

Down-regulated m6A reader FTO destabilizes PHF1 that triggers enhanced stemness capacity and tumor progression in lung adenocarcinoma

Aberrant epigenetic drivers or suppressors contribute to LUAD progression and drug resistance, including KRAS, PTEN, Keap1. Human Plant Homeodomain (PHD) finger protein 1 (PHF1) coordinates with H3K36me3 to increase nucleosomal DNA accessibility. Previous studies revealed that PHF1 is markedly upregulated in various tumors and enhances cell proliferation, migration and tumorigenesis. However, its roles in LUAD are still unknown. We aimed to depict the biological roles of PHF1 and identify useful targets for clinical treatment of LUAD. Based on the bioinformatic analysis, we found that PHF1 was down-regulated in LUAD samples and low PHF1 expressions correlated with unfavorable clinical characteristics. Patients with low PHF1 had poorer survival outcomes relative to those with high PHF1. Targeting PHF1 potentiated cell growth, migration and in vivo proliferation. Mechanistically, FTO mediated the stabilization of PHF1 mRNA by demethylating m6A, which particularly prevented YTHDF2 from degrading PHF1 transcripts. Of note, FTO also expressed lowly in LUAD that predicts poor prognosis of patients. FTO inhibition promoted LUAD progression, and PHF1 overexpression could reverse the effect. Lastly, down-regulated FTO/PHF1 axis could mainly elevate FOXM1 expression to potentiate the self-renewal capacity. Targeting FOXM1 was effective to suppress PHF1low/− LUAD growth. Collectively, our findings revealed that FTO positively regulates PHF1 expression and determined the tumor-suppressive role of FTO/PHF1 axis, thereby highlighting insights into its epigenetic remodeling mechanisms in LUAD progression and treatment.

GPR37 promotes cancer growth by binding to CDK6 and represents a new theranostic target in lung adenocarcinoma

Lung adenocarcinoma (LUAD) is associated with poor prognosis. Identifying novel cancer targets and helpful therapeutic strategies remains a serious clinical challenge. This study detected differentially expressed genes in The Cancer Genome Atlas (TCGA) LUAD data collection. We also identified a predictive DNA biomarker, G protein-coupled receptor 37 (GPR37), which was verified as a prognostic biomarker with a critical role in tumor progression. In human LUAD specimens and microarray analyses, we determined that GPR37 was significantly upregulated and associated with a poor prognosis. GPR37 downregulation markedly inhibited the proliferation and migration of LUAD both in vitro and in vivo. Mechanistically, GPR37 could bind to CDK6, thereby facilitating tumor progression in LUAD by inducing cell cycle arrest at the G1 phase. GPR37 also facilitates tumorigenesis in xenograft tumors in vivo. High-throughput screening for GPR37-targeted drugs was performed using the Natural Products Library, which revealed the potential of Hypocrellin B to inhibit GPR37 and cell growth in LUAD. We demonstrated that Hypocrellin B suppressed LUAD cell proliferation and migration both in vitro and in vivo via GPR37 inhibition. Collectively, our findings reveal the role of GPR37 in LUAD progression and migration and the potential of GPR37 as a target for the treatment of LUAD. Thus, the specific inhibition of GPR37 by the natural product Hypocrellin B may possess the potential for the treatment of LUAD.

Clinical M2 Macrophage-Related Genes Can Serve as a Reliable Predictor of Lung Adenocarcinoma.

BackgroundNumerous studies have found that infiltrating M2 macrophages play an important role in the tumor progression of lung adenocarcinoma (LUAD). However, the roles of M2 macrophage infiltration and M2 macrophage-related genes in immunotherapy and clinical outcomes remain obscure.MethodsSample information was extracted from TCGA and GEO databases. The TIME landscape was revealed using the CIBERSORT algorithm. Weighted gene co-expression network analysis (WGCNA) was used to find M2 macrophage-related gene modules. Through univariate Cox regression, lasso regression analysis, and multivariate Cox regression, the genes strongly associated with the prognosis of LUAD were screened out. Risk score (RS) was calculated, and all samples were divided into high-risk group (HRG) and low-risk group (LRG) according to the median RS. External validation of RS was performed using GSE68571 data information. Prognostic nomogram based on risk signatures and other clinical information were constructed and validated with calibration curves. Potential associations of tumor mutational burden (TMB) and risk signatures were analyzed. Finally, the potential association of risk signatures with chemotherapy efficacy was investigated using the pRRophetic algorithm.ResultsBased on 504 samples extracted from TCGA database, 183 core genes were identified using WGCNA. Through a series of screening, two M2 macrophage-related genes (GRIA1 and CLEC3B) strongly correlated with LUAD prognosis were finally selected. RS was calculated, and prognostic risk nomogram including gender, age, T, N, M stage, clinical stage, and RS were constructed. The calibration curve shows that our constructed model has good performance. HRG patients were suitable for new ICI immunotherapy, while LRG was more suitable for CTLA4-immunosuppressive therapy alone. The half-maximal inhibitory concentrations (IC50) of the four chemotherapeutic drugs (metformin, cisplatin, paclitaxel, and gemcitabine) showed significant differences in HRG/LRG.ConclusionsIn conclusion, a comprehensive analysis of the role of M2 macrophages in tumor progression will help predict prognosis and facilitate the advancement of therapeutic techniques.

Overexpression of SFXN1 indicates poor prognosis and promotes tumor progression in lung adenocarcinoma

Sideroflexin 1 (SFXN1) functions as a mitochondrial serine transporter in one-carbon metabolism. The association between SFXN1 and tumorigenesis remains to be elucidated. This study illustrated the functional role of SFXN1 in lung adenocarcinoma (LUAD). SFXN1 expression in LUAD specimens was examined using western blotting and quantitative real-time PCR (qRT-PCR), and the prognostic value between SFXN1 and clinicopathological parameters was investigated. Subsequently, the effects of SFXN1 on cellular proliferation, migration, and apoptosis were assessed by using Transwell assays and flow cytometry in A549 and H1299 cell lines. Western blotting was also employed to explore the mechanism of tumor progression. SFXN1 was significantly elevated in the LUAD samples compared with the para-carcinoma tissues. Furthermore, SFXN1 expression was an independent prognostic predictor for patients with LUAD. The expression of SFXN1 was altered in A549 and H1299 cell lines and this showed that SFXN1 promoted cell proliferation, migration, and invasion and inhibited apoptosis. SFXN1, at least partially, influenced LUAD progression via the mTOR signaling pathway. Collectively, the findings from this study demonstrated that SFXN1 promotes LUAD progression via the mTOR pathway and that SFXN1 expression is associated with clinicopathological features of LUAD. SFXN1 significantly contributes to the development of LUAD and might have potential, not only as an independent prognostic marker of LAUD but also as a promising target for LUAD therapy.

State-of-the-Art Molecular Oncology of Lung Cancer in Taiwan.

Lung cancers are life-threatening malignancies that cause great healthcare burdens in Taiwan and worldwide. The 5-year survival rate for Taiwanese patients with lung cancer is approximately 29%, an unsatisfactorily low number that remains to be improved. We first reviewed the molecular epidemiology derived from a deep proteogenomic resource in Taiwan. The nuclear factor erythroid 2-related factor 2 (NRF2)antioxidant mechanism was discovered to mediate the oncogenesis and tumor progression of lung adenocarcinoma. Additionally, DNA replication, glycolysis and stress response are positively associated with tumor stages, while cell-to-cell communication, signaling, integrin, G protein coupled receptors, ion channels and adaptive immunity are negatively associated with tumor stages. Three patient subgroups were discovered based on the clustering analysis of protein abundance in tumors. The first subgroup is associated with more advanced cancer stages and visceral pleural invasion, as well as higher mutation burdens. The second subgroup is associated with EGFR L858R mutations. The third subgroup is associated with PI3K/AKT pathways and cell cycles. Both EGFR and PI3K/AKT signaling pathways have been shown to induce NRF2 activation and tumor cell proliferation. We also reviewed the clinical evidence of patient outcomes in Taiwan given various approved targeted therapies, such as EGFR-tyrosine kinase inhibitors and anaplastic lymphoma kinase (ALK)inhibitors, in accordance with the patients’ characteristics. Somatic mutations occurred in EGFR, KRAS, HER2 and BRAF genes, and these mutations have been detected in 55.7%, 5.2%, 2.0% and 0.7% patients, respectively. The EGFR mutation is the most prevalent targetable mutation in Taiwan. EML4-ALK translocations have been found in 9.8% of patients with wild-type EGFR. The molecular profiling of advanced NSCLC is critical to optimal therapeutic decision-making. The patient characteristics, such as mutation profiles, protein expression profiles, drug-resistance profiles, molecular oncogenic mechanisms and patient subgroup systems together offer new strategies for personalized treatments and patient care.

Abstract 2720: Unbiased identification of RNA splicing-defined patient populations in lung adenocarcinoma

Abstract Aberrant alternative splicing is known to directly contribute to tumor progression in lung adenocarcinoma (LUAD). While the action of individual splicing variants as cancer drivers have been characterized in LUAD, the global splicing landscape and how that corresponds to patient prognosis is poorly understood. Using whole transcriptome RNA-Seq data provided from The Cancer Genome Atlas (TCGA), we applied a new computational pipeline, OncoSplice, to identify potentially novel prognostic disease splicing subtypes and elucidate the biological mechanisms underlying these subtypes. OncoSplice identified over 30 novel splicing-defined subtypes of LUAD, several of which correlate with worse patient survival. Additionally, we identified patient clusters that were significantly enriched in mutations for RNA binding proteins, such as Cap Methyltransferase 2 (CMTR2) and RNA Binding Motif 10 (RBM10). More specifically, mutations in the splicing factor RBM10 were found to be enriched but not requisite for the dominant poor prognosis splicing subtype in LUAD. In non-mutant patients within this subset, RBM10 gene expression downregulation was induced, mimicking the mutation phenotype. Hence, we find alternative non-genetic pathways for impacting splicing in LUAD that leads to poor prognosis through disruption of canonical splicing. Citation Format: Audrey Crowther. Unbiased identification of RNA splicing-defined patient populations in lung adenocarcinoma [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 2720.

Abstract 2382: Aberrant glycogen accumulation alters gene expression and promotes lung tumor progression in vivo

Abstract Lung cancer is one of the most prevalent cancers worldwide, accounting for nearly two million new cases each year. Lung adenocarcinoma (LUAD) is the most common subtype of lung cancer and is the leading cause of cancer related mortalities worldwide. LUAD has an extremely poor five-year survival rate, which is likely due to cases being diagnosed at advanced stages and thus being more difficult to treat the metastatic disease. Identifying the molecular processes that contribute to disease progression is a critical goal in lung cancer research that could lead to predictive biomarkers and novel therapies. Glycogen is the primary form of carbohydrate storage in mammalian cells, and its degradation product, Glucose 6-Phosphate (G6P) feeds directly into glycolysis, making glycogen intimately connected to central carbon metabolism. Recently, aberrant glycogen accumulation in lung tumors has been reported to promote lung cancer progression, driven by largely unknown mechanisms. We recently generated a transgenic KRASG12D/p53-/- LUAD mouse model that also lacks the glycogen phosphatase laforin (LKO). This model develops increased glycogen accumulation in the lungs and displays accelerated tumor growth compared to the KRASG12D/p53-/- control (WT), as measured by Ki67 staining. To identify potential biological processes perturbed by LUAD-glycogen, we performed RNA-seq on lung tumors resected from WT and LKO mice. We identified over 300 genes that are differentially expressed between WT and LKO lung tumors. Specifically, gene set enrichment analysis (GSEA) revealed genes that were upregulated in LKO lung tumors were involved in extracellular matrix remodeling, cell-to-cell communication, and cell proliferation. All of these processes are implicated in tumor growth, which supports our initial observation that LKO mice have increased tumor burden and disease progression. Our findings ultimately highlight several potential mechanisms by which LUAD-glycogen promotes LUAD tumor progression, which can be further investigated to identify novel biomarkers and therapeutic targets. Citation Format: Jessica Faith Lamb, Lindsey R. Conroy, Alexis N. James, Michael D. Buoncristiani, Eric R. Relich, Lindsay E. Young, Christine F. Branson, Ramon C. Sun. Aberrant glycogen accumulation alters gene expression and promotes lung tumor progression in vivo [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 2382.

Fatty acid binding protein 5 regulates lipogenesis and tumor growth in lung adenocarcinoma

AimsLung cancer is the leading cause of cancer-related death. Unfortunately, targeted-therapies have been unsuccessful for most patients with lung adenocarcinoma (LUAD). Thus, new early biomarkers and treatment options are a pressing need. Fatty acid binding protein 5 (FABP5) has been associated with various types of cancers. Its contribution to LUAD onset, progression and metabolic reprogramming is, however, not fully understood. In this study we assessed the importance of FABP5 in LUAD and its role in cancer lipid metabolism. Main methodsBy radioactive labeling and metabolite quantification, we studied the function of FABP5 in fatty acid metabolism using genetic/pharmacologic inhibition and overexpression models in LUAD cell lines. Flow cytometry, heterologous transplantation and bioinformatic analysis were used, in combination with other methodologies, to assess the importance of FABP5 for cellular proliferation in vitro and in vivo and in patient survival. Key findingsWe show that high expression of FABP5 is associated with poor prognosis in patients with LUAD. FABP5 regulates lipid metabolism, diverting fatty acids towards complex lipid synthesis, whereas it does not affect their catabolism in vitro. Moreover, FABP5 is required for de novo fatty acid synthesis and regulates the expression of enzymes involved in the pathway (including FASN and SCD1). Consistently with the changes in lipid metabolism, FABP5 is required for cell cycle progression, migration and in vivo tumor growth. SignificanceOur results suggest that FABP5 is a regulatory hub of lipid metabolism and tumor progression in LUAD, placing it as a new putative therapeutic target for this disease.