Small Cell Lung Cancer Tissues Research Articles

The Role and Mechanism of IFITM1 in Developing Acquired Cisplatin Resistance in Small Cell Lung Cancer

Platinum-based chemotherapies, historically the cornerstone of first-line treatment for small-cell lung cancer (SCLC), face a major hurdle: the frequent emergence of chemoresistance, notably to cisplatin (CDDP). Current understanding of the mechanisms driving CDDP resistance in SCLC is incomplete. Notably, Interferon inducible transmembrane protein1 (IFITM1) has been identified as a key player in the distant metastasis of SCLC. Analysis of The Cancer Genome Atlas (TCGA) database revealed that IFITM1 expression is markedly elevated in tumor tissues as compared to that from adjacent normal tissues, correlating with a worse prognosis for patients with SCLC. Our research focused on investigating the role of IFITM1 in the acquisition of cisplatin resistance in SCLC. Further clinical sample analysis highlighted a significant increase in IFITM1 levels in SCLC tissues from cisplatin-resistant patients versus those were responsive to CCDP treatment, with similar trends observed in cisplatin-resistant SCLC cells. Crucially, overexpression of IFITM1 reduced the sensitivity of SCLC cells to cisplatin, while silencing IFITM1 enhanced chemosensitivity in cisplatin-resistant strains. Our in vivo studies further confirmed that silencing IFITM1 significantly boosted the efficacy of cisplatin in inhibiting growth of subcutaneous tumors of NCI-H466/CDDP cells (cisplatin-resistant SCLC cells) in a mouse model. Mechanistically, IFITM1 appears to foster cisplatin resistance through activation of the Wnt/β-catenin pathway. In summary, our findings suggest that targeting IFITM1, alongside cisplatin treatment, could offer a promising therapeutic strategy to overcome resistance and improve outcomes for SCLC patients.

FAK-LINC01089 negative regulatory loop controls chemoresistance and progression of small cell lung cancer.

The focal adhesion kinase (FAK) tyrosine kinase is activated and upregulated in multiple cancer types including small cell lung cancer (SCLC). However, FAK inhibitors have shown limited efficacy in clinical trials for cancer treatment. With the aim of identifying potential therapeutic strategies to inhibit FAK for cancer treatment, we investigated long non-coding RNAs (lncRNAs) that potentially regulate FAK in SCLC. In this study, we identified a long non-coding RNA LINC01089 that binds and inhibits FAK phosphorylation (activation). Expression analysis revealed that LINC01089 was downregulated in SCLC tissues and negatively correlated with chemoresistance and survival in SCLC patients. Functionally, LINC01089 inhibited chemoresistance and progression of SCLC in vitro and in vivo. Mechanistically, LINC01089 inhibits FAK activation by blocking binding with Src and talin kinases, while FAK negatively regulates LINC01089 transcription by activating the ERK signaling pathway to recruit the REST transcription factor. Furthermore, LINC01089-FAK axis mediates the expression of drug resist-related genes by modulating YBX1 phosphorylation, leading to drug resistance in SCLC. Intriguingly, the FAK-LINC01089 interaction depends on the co-occurrence of the novel FAK variant and the non-conserved region of LINC01089 in primates. In Conclusion, our results indicated that LINC01089 may serve as a novel high-efficiency FAK inhibitor and the FAK-LINC01089 axis represents a valuable prognostic biomarker and potential therapeutic target in SCLC.

Abstract 1722: Subtype classification of small cell lung cancer (SCLC) tissues using the EpiCheck methylation sensitive restriction-based PCR platform

Abstract Small cell lung cancer (SCLC) is an aggressive neuroendocrine malignancy with poor survival rates. Despite molecular and clinical heterogeneity, SCLC is currently treated as a single entity without guidance of predictive biomarkers leading to expectedly poor outcomes. A recent study suggested classifying SCLC into four subtypes (“A”, “N”, “P” and “I”), each with unique molecular features and therapeutic vulnerabilities. While initially this classification was based on gene expression (RNA-seq) data, subsequent data suggest it can be recapitulated using reduced-representation bisulfite sequencing (RRBS) methylation profile. While the classification system accurately predicts responses to therapies, including immunotherapies, in retrospective analysis, both tissue-based RNAseq and RRBS are cumbersome, time-consuming and impractical for prospective treatment assignment in an aggressive malignancy. In this pilot study, we developed a methylation-based PCR assay for classification of SCLC subtypes based on the EpiCheck platform, which combines methylation-sensitive restriction endonuclease (MSRE) digestion with qPCR amplification to detect differential methylation at the DNA level. We developed a 13-marker assay and successfully classified, in a blinded study, 96.55% of FFPE tissue samples originating from SCLC patient of A, N and P subtypes. First, a bioinformatic analysis identified 41 candidate biomarkers that are differentially methylated between pairs of SCLC subtypes (A-N, A-P, and N-P) using RRBS data from 56 RNA-seq classified SCLC tumor samples (34 “A”, 19 “N”, 3 “P”). Development of primers and probes for these markers was followed by a biochemical selection process, identifying 13 markers that displayed optimal performance. A PCR EpiCheck assay, employing these 13 markers, was applied to a blinded set of 29 DNA samples from SCLC FFPE tumor tissues (21 “A”, 6 “N”, 2 “P”). Each sample received two ranks based on methylation levels of 5 A-N and 9 P-AN markers and was classified using determined thresholds for each rank. Finally, when comparing PCR-based and RNA-seq-based classifications, the 13-marker PCR assay classified 28/29 (96.55%) of the samples concordantly, misclassifying one "P" sample as "A". This pilot demonstrates the potential of a simple PCR EpiCheck-based assay to accurately differentiate between SCLC subtypes. For complete subtype classification, “I” markers need to be added to the panel, and the assay should be further validated using a larger cohort, particularly for the “P” subtype. Early detection and classification are critical for timely personalized therapy, and such an assay, performed on cfDNA samples, could potentially be used to shorten the time between a patient diagnosis and tailored treatment initiation or clinical study inclusion from a month in best case scenarios to a few days. Citation Format: Orna Savin, Dvir Netanely, Simon Heeke, Carl Michael Gay, Marcos Roberto Estecio, Shacade Danan, Sarah Zaouch, Aharona Shuali, Mathias Ehrich, Lauren Averett Byers, John Victor Heymach, Adam Wasserstrom, Danny Frumkin. Subtype classification of small cell lung cancer (SCLC) tissues using the EpiCheck methylation sensitive restriction-based PCR platform [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1722.

HMOX1 regulates ferroptosis via mic14 and its impact on chemotherapy resistance in small-cell lung cancer.

This study aimed to investigate the role and molecular mechanism of heme oxygenase-1 (HMOX1) in chemotherapy resistance in small-cell lung cancer (SCLC). Employed bioinformatics, qPCR, and Western Blot to assess HMOX1 levels in SCLC versus normal tissues and its prognostic relevance. CCK-8, flow cytometry, and thiobarbituric acid assays determined HMOX1's impact on SCLC chemosensitivity, ferroptosis markers, lipid peroxidation, and mic14's role in chemoresistance. In the GSE40275 and GSE60052 cohorts, HMOX1 expression was downregulated in SCLC tissues compared to normal tissues. Higher HMOX1 expression was associated with improved prognosis in the Sun Yat-sen University Cancer Hospital cohort and GSE60052 cohort. The RNA and protein levels of HMOX1 were reduced in drug-resistant SCLC cell lines compared to chemosensitive cell lines. Upregulation of HMOX1 increased chemosensitivity and reduced drug resistance in SCLC, while downregulation of HMOX1 decreased chemosensitivity and increased drug resistance. Upregulation of HMOX1 elevated the expression of ferroptosis-related proteins ACSL4, CD71, Transferrin, Ferritin Heavy Chain, and Ferritin Light Chain, while decreasing the expression of GPX4 and xCT. Conversely, downregulation of HMOX1 decreased the expression of ACSL4, CD71, Transferrin, Ferritin Heavy Chain, and Ferritin Light Chain, while increasing the expression of GPX4 and xCT. Upregulation of HMOX1 promoted cellular lipid peroxidation, whereas downregulation of HMOX1 inhibited cellular lipid peroxidation. Upregulation of HMOX1 reduced the RNA level of mic14, while downregulation of HMOX1 increased the RNA level of mic14. mic14 exhibited inhibitory effects on cellular lipid peroxidation in SCLC cells and contributed to reduced chemosensitivity and increased drug resistance in chemoresistant SCLC cell lines. HMOX1 plays a role in ferroptosis by regulating mic14 expression, thereby reversing chemoresistance in SCLC.

Dynamic phenotypic reprogramming and chemoresistance induced by lung fibroblasts in small cell lung cancer.

Small cell lung cancer (SCLC) is heterogenous in phenotype and microenvironment. Dynamic phenotypic reprogramming, leading to heterogeneity, is prevalent in SCLC, while the mechanisms remain incompletely understood. Cancer-associated fibroblasts (CAFs) possess comprehensive roles in cancer progression, while their function in phenotypic reprogramming of SCLC remain elusive. Here, we obtained transcriptome data of SCLC tissues from publicly available databases, subsequently estimated abundance of CAFs. We found CAF-abundant SCLC exhibited non-neuroendocrine (Non-NE) characteristics. Supporting this, the positive correlation of expression level of α-SMA, the CAF marker, and expression level of REST, protein typically expressed in Non-NE type SCLC, was identified in SCLC tissue arrays. Moreover, we revealed that fibroblasts inhibited NE markers expression and cell proliferation of SCLC cells in the co-culture system comprising lung fibroblasts and SCLC cells, indicating a phenotypic reprogramming from NE to Non-NE. During this process, fibroblast-derived IL-6 activated the JAK2/STAT3 signaling, upregulated c-MYC expression, and subsequently activated the NOTCH pathway, driving phenotypic reprogramming. Moreover, CAF-enriched SCLC exhibited increased immune cell infiltration, elevated expression of immune activation-related signatures, and checkpoint molecules. Our data also highlighted the chemoresistance induced by fibroblasts in SCLC cells, which was effectively reversed by JAK inhibitor. In conclusion, fibroblasts induced phenotypic reprogramming of SCLC cells from NE to Non-NE, likely contributes to inflamed immune microenvironment and chemoresistance. These findings provide novel insights into the clinical implications of CAFs in SCLC.

ITPR1-AS1 promotes small cell lung cancer metastasis by facilitating P21HRAS splicing and stabilizing DDX3X to activate the cRaf-MEK-ERK cascade

The mechanisms underlying the involvement of long non-coding RNAs (lncRNAs) in the metastasis of small cell lung cancer (SCLC) remain largely unknown. Here, we identified that the lncRNA ITPR1-AS1 was upregulated in SCLC and lymph node metastasis tissues and positively correlated with SCLC malignant features. The overexpression of ITPR1-AS1 in SCLC was an independent risk factor for the overall survival of patients with SCLC. Our data confirmed that ITPR1-AS1 induces SCLC cell metastasis both in vitro and in vivo. Mechanistically, ITPR1-AS1 acts as a scaffold to enhance the interaction between SRC-associated in mitosis 68 kDa and heterogeneous nuclear ribonucleoprotein A1, which facilitates the alternative splicing of the H-Ras proto-oncogene (HRAS) pre-mRNA (P21HRAS). Moreover, we observed that ITPR1-AS1 could associate in a complex with and maintain the stability of DEAD-box polypeptide 3 (DDX3X), which inhibited the latter’s ubiquitination and degradation. Our data provide evidence that ITPR1-AS1 activates the cRaf-MEK-ERK cascade by upregulating P21HRAS production and stabilizing DDX3X, to promote SCLC metastasis.

ACAA2 is a novel molecular indicator for cancers with neuroendocrine phenotype

BackgroundNeuroendocrine phenotype is commonly associated with therapy resistance and poor prognoses in small-cell neuroendocrine cancers (SCNCs), such as neuroendocrine prostate cancer (NEPC) and small-cell lung cancer (SCLC). Expression levels of current neuroendocrine markers exhibit high case-by-case variability, so multiple markers are used in combination to identify SCNCs. Here, we report that ACAA2 is elevated in SCNCs and is a potential molecular indicator for SCNCs.MethodsACAA2 expressions in tumour xenografts, tissue microarrays (TMAs), and patient tissues from prostate and lung cancers were analysed via immunohistochemistry. ACAA2 mRNA levels in lung and prostate cancer (PC) patients were assessed in published datasets.ResultsACAA2 protein and mRNA levels were elevated in SCNCs relative to non-SCNCs. Medium/high ACAA2 intensity was observed in 78% of NEPC PDXs samples (N = 27) relative to 33% of adeno-CRPC (N = 86), 2% of localised PC (N = 50), and 0% of benign prostate specimens (N = 101). ACAA2 was also elevated in lung cancer patient tissues with neuroendocrine phenotype. 83% of lung carcinoid tissues (N = 12) and 90% of SCLC tissues (N = 10) exhibited medium/high intensity relative to 40% of lung adenocarcinoma (N = 15).ConclusionACAA2 expression is elevated in aggressive SCNCs such as NEPC and SCLC, suggesting it is a potential molecular indicator for SCNCs.

Targeting CDH17 with Chimeric Antigen Receptor-Redirected T Cells in Small Cell Lung Cancer.

Chimeric antigen receptor T cell (CAR-T) therapy stands as a precise and targeted approach in the treatment of malignancies. In this study, we investigated the feasibility of targeting Cadherin 17 (CDH17) with CDH17 CAR-T cells as a therapeutic modality for small cell lung cancer (SCLC). CDH17 expression levels were assessed in human SCLC tumor tissues and cell lines using qPCR and Western blot. Subsequently, we established CDH17 CAR-T cells and assessed their cytotoxicity by co-culturing them with various SCLC cell lines at different effector-to-target (E:T) ratios, complemented by ELISA assays. To ascertain the specificity of CDH17 CAR-T cells, we conducted experiments on SCLC cells with and without CDH17 expression (shRNAs). Furthermore, we employed an SCLC xenograft model to evaluate the in vivo efficacy of CDH17 CAR-T cells. Our results revealed a significant upregulation of CDH17 in both SCLC tissues and cell lines. CDH17 CAR-T cells exhibited robust cytotoxic activity against SCLC cells in vitro, while demonstrating no cytotoxicity towards CDH17-deficient SCLC cells and HEK293 cells that lack CDH17 expression. Importantly, the production of IFN-γ and TNF-α by CDH17 CAR-T cells correlated with their cytotoxic potency. Additionally, treatment with CDH17 CAR-T cells significantly decelerated the growth rate of SCLC-derived xenograft tumors in vivo. Remarkably, no significant difference in body weight was observed between the control group and the group treated with CDH17 CAR-T cells. The preclinical data open further venues for the clinical use of CDH17 CAR-T cells as an immunotherapeutic strategy for SCLC treatment.

Bioinformatics-based screening of key genes for transformation of tyrosine kinase inhibitor-resistant lung adenocarcinoma to small cell lung cancer.

Lung adenocarcinoma (LUAD) is a common type of lung cancer. Cancer in a small number of patients with EGFR mutations will transform from LUAD to small cell lung cancer (SCLC) during epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) therapiesr. The purpose of the present study was to identify the core genes related to the transformation of LUAD into SCLC and to explore the associated molecular mechanisms. GSE29016, GSE1037, GSE6044 and GSE40275 mRNA microarray datasets from Gene Expression Omnibus (GEO) were analyzed to obtain differentially expressed genes (DEGs) between LUAD and SCLC tissues, and the results were used for network analysis of protein-protein interactions (PPIs). After identifying the hub gene by STRING and Cytoscape platform, we explored the relationship between hub genes and the occurrence and development of SCLC. Finally, the obtained hub genes were validated in treated LUAD cells. A total of 41 DEGs were obtained, four hub genes (EZH2, NUSAP1, TTK and UBE2C) were identified, and related prognostic information was obtained. The coexpressed genes of the hub gene set were further screened, and the analysis identified many genes related to the cell cycle. Subsequently, LUAD cell models with TP53 and RB1 inactivation and overexpression of ASCL1 were constructed, and then the expression of hub genes was detected, the results showed that the four hub genes were all elevated in the established cell model. EZH2, NUSAP1, TTK and UBE2C may affect the transformation of LUAD to SCLC and represent new candidate molecular markers for the occurrence and development of SCLC.

Machine Learning Model-based Detection of Potential Genetic Markers Associated with the Diagnosis of Small-cell Lung Cancer

Background: Small-cell lung cancer (SCLC), which is in the category of intractable cancers, has a low survival rate. It is essential to understand the pathophysiological pathways underlying its development to create powerful treatment alternatives for the disease. Objectives: This study aimed to classify gene expression data from SCLC and normal lung tissue and identify the key genes responsible for SCLC. Methods: This study used microarray expression data obtained from SCLC tissue and normal lung tissue (adjacent tissue) from 18 patients. An Extreme Gradient Boosting (XGBoost) model was established for the classification by five-fold cross-validation. Accuracy (AC), balanced accuracy (BAC), sensitivity (Sens), specificity (Spec), positive predictive value (PPV), negative predictive value (NPV), and F1 scores were utilized for performance assessment. Results: AC, BAC, Sens, Spec, PPV, NPV, and F1 scores from the XGBoost model were 90%, 90%, 80%, 100%, 100%, 83.3%, and 88.9%, respectively. Based on variable importance values from the XGBoost, the HIST1H1E, C12orf56, DSTNP2, ADAMDEC1, and HMGB2 genes can be considered potential biomarkers for SCLC. Conclusion: A machine learning-based prediction method discovered genes that potentially serve as biomarkers for SCLC. After clinical confirmation of the acquired genes in the following medical study, their therapeutic use can be established in clinical practice.

CEMIP-mediated hyaluronan metabolism facilitates SCLC metastasis by activating TLR2/c-Src/ERK1/2 axis.

Small-cell lung cancer (SCLC) is a highly metastatic and recalcitrant malignancy. Metastasis is the major cause of death in patients with SCLC but its mechanism remains poorly understood. An imbalance of hyaluronan catabolism in the extracellular matrix accelerates malignant progression in solid cancers due to the accumulation of low-molecular-weight HA. We previously found that CEMIP, a novel hyaluronidase, may act as a metastatic trigger in SCLC. In the present study, we found that both CEMIP and HA levels were higher in SCLC tissues than in paracancerous tissues from patient specimens and in vivo orthotopic models. Additionally, high expression of CEMIP was associated with lymphatic metastasis in patients with SCLC, and in vitro results showed that CEMIP expression was elevated in SCLC cells relative to human bronchial epithelial cells. Mechanistically, CEMIP facilitates the breakdown of HA and accumulation of LMW-HA. LMW-HA activates its receptor TLR2, and subsequently recruits c-Src to activate ERK1/2 signalling, thereby promoting F-actin rearrangement as well as migration and invasion of SCLC cells. In addition, the in vivo results verified that depletion of CEMIP attenuated HA levels and the expressions of TLR2, c-Src, and phosphorylation of ERK1/2, as well as liver and brain metastasis in SCLC xenografts. Furthermore, the application of the actin filament inhibitor latrunculin A significantly inhibited the liver and brain metastasis of SCLC in vivo. Collectively, our findings reveal the critical role of CEMIP-mediated HA degradation in SCLC metastasis and suggest its translational potential as an attractive target and a novel strategy for SCLC therapy.

Identification and Validation of Cyclin A2 and Cyclin E2 as Potential Biomarkers in Small Cell Lung Cancer

Introduction: Small cell lung cancer (SCLC) is a special type of lung cancer sensitive to radiotherapy and chemotherapy but is prone to drug resistance and recurrence and has a very poor prognosis. This study aimed to explore the potential biomarkers and therapeutic targets for SCLC. Methods: After batch normalization of GSE40275, GSE1037, and GSE44447 datasets, R was used to screen SCLC’s differentially expressed genes (DEGs) and hub genes. We used immunohistochemistry (IHC) to assess the tissue’s expression level of the hub gene. The clinical value of the hub gene was further evaluated based on the collected clinical-pathological data. Results: In this study, a total of 230 DEGs (133 upregulated and 97 downregulated) were screened by the R package. The IHC showed that the expression of CCNA2 and CCNE2 in SCLC tissues was significantly higher than that in normal tissues (p < 0.01). Overexpression of CCNA2 was closely associated with the extensive period of NCCN (p = 0.004), tumor position (p = 0.046), and clinical stage (p = 0.002). The high expression levels of CCNE2 were related to high survival in chemotherapy patients (p = 0.019). Conclusion: CCNA2 and CCNE2 may serve as potential biomarkers of diagnosis and treatment for SCLC.

Abstract 3196: Subtype-specific targeting of cell surfaceome with CAR T therapies in small cell lung cancer

Abstract Background: Small cell lung cancer (SCLC) is a highly lethal malignancy with limited treatment options. Most SCLC are “immune-cold” and respond poorly to immunotherapy. Targeting SCLC cell surfaceome with cellular therapies have shown promising efficacy and tolerability in DLL3-targeting CAR T (AMG119) and Bispecific T-cell engager (tarlatamab). Recent work has defined subtypes of SCLC based on master transcription factors ASCL1 (SCLC-A), NEUROD1 (SCLC-N), POU2F3 (SCLC-P) and an immune cell-rich “inflamed” subtype(SCLC-I). Notably, SCLC-A and SCLC-N express neuroendocrine (NE) features while SCLC-P and SCLC-I are non-neuroendocrine (non-NE). We hypothesize that SCLC may have distinct surfaceome expressions based on their subtypes, which can be successfully targeted with cellular therapies such as CAR T. Methods: Transcriptional profiling of patient tumors identified several putative cell surfaceome targets in SCLC. We confirmed their expression level by Western blot and flow cytometry in SCLC cell lines stratified by subtypes. Top targets were selected based on abundant expression in SCLC and restricted normal tissue expression. We then constructed third-generation CAR T-cells against the top targets and tested their efficacy in cancer cell/CAR T co-culture models and in vivo. Results: We validated cell surface expression of top targets DLL3, CD56 and GD2; and generated CAR Ts against these targets to test cytotoxicity across a large panel of SCLC cell lines. Specifically, DLL3 is present predominantly in SCLC-A and SCLC-N (NE) subtypes. CAR T against DLL3 showed robust cytotoxicity in vitro against DLL3-expressing cell lines (5 out of 6 SCLC-A/N cell lines, versus 1 out of 6 SCLC-P/I cell lines; median cytotoxicity 94% vs. 43%, p=0.0082, Mann-Whitney U test), as well as promising in vivo activity. We also confirmed CD56 (NCAM1) was broadly expressed on the cell surface in SCLC A/P/N subtypes, and 8 out of 9 cell lines with high CD56 expression demonstrated over 50% cytotoxicity in co-culture models. GD2 was found to be enriched specifically in SCLC-N subtype of SCLC. As expected, GD2-targeting CAR T had higher cytotoxicity in SCLC-N subtypes of SCLC compared to other subtypes (median cytotoxicity 91% vs 22%, p=0.047). Moreover, given that novel therapeutics are often tested in the relapsed setting, we tested target expressions in SCLC cell lines after treatment with cisplatin and etoposide (standard frontline chemotherapy for SCLC) to see if target levels change. We found that surface target expressions increased instead of decreased in most cell lines, suggesting that they may be suitable targets in the relapsed setting also. Conclusion: This study demonstrated efficacy of CAR Ts targeting several cell surfaceome targets enriched in certain subtypes of SCLC. The data supports further investigation of a subtype-specific personalized treatment of SCLC using CAR T therapies against surfaceome targets. Citation Format: Bingnan Zhang, Yan Yang, C.Allison Stewart, Kavya Ramkumar, Runsheng Wang, Robert Cardnell, Lixia Diao, Qi Wang, Jing Wang, Lauren Byers, Carl Gay, John Heymach. Subtype-specific targeting of cell surfaceome with CAR T therapies in small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3196.

Abstract 289: B7-H3 mediated metabolic reprogramming promotes small cell lung cancer progression

Abstract Lung cancer is the leading cause of cancer-related deaths worldwide. Small cell lung cancer (SCLC) is an aggressive subtype of lung cancer. The overall survival rate of SCLC is dismal owing to early metastasis, chemoresistance, higher rate of recurrence, and lack of available treatment options. Although some immunotherapeutic drugs have been approved for SCLC, they are effective only in a small fraction of the patient population. This necessitates the quest to find promising vulnerabilities against SCLC. Bioinformatic analysis on SCLC data set in the backdrop of various immune checkpoint regulators revealed B7-H3 as a promising target. The bioinformatics data was recapitulated in SCLC cell lines and human SCLC tissues. To delineate the effects of B7-H3 targeting, we performed CRISPR-Cas9 mediated B7-H3 knockout in SCLC cell lines. B7-H3 knockout in SCLC cells showed a decrease in colony formation, migration, and wound healing properties. Our results suggest that deletion of B7-H3 decrease the functional activities and activation of oncogenic signaling pathways, such as Erk, Akt, and Stat3. Further, we assessed if B7-H3 regulates SCLC metabolism. Preliminary data showed that B7-H3 knockout in SCLC cells inhibits glucose uptake, extracellular acidification rate (ECAR), and oxygen consumption rate (OCR), suggesting its role in SCLC metabolic reprogramming. Altogether, our data indicate that B7-H3 plays a crucial role in SCLC pathogenesis and could serve as a potential therapeutic target for SCLC. Citation Format: Mahek Fatima, Parvez Khan, Asad Ur Rehman, Md Arafat Khan, Shailendra Kumar Maurya, Aatiya Ahmad, Mohd Ali Zaidi, Shailendra Gautam, Subodh Lele, Surinder Kumar Batra, Mohd Wasim Nasser. B7-H3 mediated metabolic reprogramming promotes small cell lung cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 289.

An immune checkpoint-based signature predicts prognosis and chemotherapy response for patients with small cell lung cancer.

Therapeutic options for small cell lung cancer (SCLC), a particularly lethal malignancy, remain limited. Members of the B7-CD28 family are compelling targets for immune checkpoint blockade strategies, which involve activating, inhibiting, and fine-tuning the T cell immune response. However, their clinical features and significance have not been explored comprehensively. We enrolled 228 patients with an initial diagnosis of SCLC, including 77 cases from Cbioportal and a validation cohort of 151 cases with qPCR data. Kaplan-Meier analysis and LASSO Cox model were used to identify a signature based on the B7-CD28 family, which was applied for accurate prediction of chemotherapy benefit and prognosis for SCLC patients. In addition, we applied bioinformatics analysis to explore potential signature-related molecular mechanisms and the immune landscape. The mutation profiles of healthy tissues and SCLC tissues were distinct. A signature consisting of seven genes (CD86, ICOSLG, CD276, CD28, CTLA-4, PDCD1, and TMIGD2) was identified and applied to group patients based on risk level (high-risk and low-risk), producing two groups for which survival outcomes differed significantly (HR=3.81, 95% CI: 2.16-6.74, P<0.001). The immune checkpoint-based signature accurately predicted patient outcomes for the selected training and validation sets. Notably, low-risk patients were more likely to benefit from chemotherapy and showed greater immune activation. Additionally, time-dependent ROC curves and C-index analysis confirmed that the immune checkpoint-based signature has excellent predictive power for prognosis and chemotherapy benefit compared to clinically recognized parameters. Finally, multivariate analysis confirmed the identified signature as an independent risk factor for prognosis and chemotherapeutic response. We systematically obtained a comprehensive molecular profile for B7-CD28 family members in SCLC patients, from which we produced a reliable and robust prognostic immune checkpoint-based signature with the potential to improve prognostic stratification and therapy strategies for SCLC patients.

CEMIP promotes small cell lung cancer proliferation by activation of glutamine metabolism via FBXW7/c-Myc-dependent axis

Small cell lung cancer (SCLC) is the most malignant lung cancer with rapid growth and early metastasis, but still lacks effective targeted therapies to improve the prognosis. Here, we demonstrated that a novel oncogenic protein, cell migration inducing hyaluronic binding protein (CEMIP), was robustly overexpressed in SCLC tissues than that in noncancerous tissues and high expression of CEMIP predicted poor outcomes in clinical specimens and in large sample size cohorts from public databases (GEPIA 2 and CPTAC). Liquid chromatography mass spectrometry (LC-MS) and in vitro/in vivo functional assays indicated that CEMIP contributed to the proliferation by increasing glutamine consumption and their metabolites (glutamate and glutathione) levels in SCLC cells. Moreover, the addition of a GLS1 inhibitor CB-839 dramatically reduced CEMIP-induced SCLC cell proliferation. Mechanistically, beyond as a scaffold protein, CEMIP facilitates glutamine-dependent cell proliferation through inhibiting c-Myc ubiquitination and increasing c-Myc stabilization and nuclear accumulation via hindering the interaction between FBXW7 (a E3 ubiquitin ligase) and its target substrate c-Myc. Taken together, our findings reveal a novel oncogenic role of CEMIP in sustaining SCLC growth via FBXW7/c-Myc-dependent axis, and provide new evidence that inhibition of CEMIP might be a potential therapeutic strategy for the treatment of SCLC.

Noncanonical splicing junctions between exons and transposable elements represent a source of immunogenic recurrent neo-antigens in patients with lung cancer.

Although most characterized tumor antigens are encoded by canonical transcripts (such as differentiation or tumor-testis antigens) or mutations (both driver and passenger mutations), recent results have shown that noncanonical transcripts including long noncoding RNAs and transposable elements (TEs) can also encode tumor-specific neo-antigens. Here, we investigate the presentation and immunogenicity of tumor antigens derived from noncanonical mRNA splicing events between coding exons and TEs. Comparing human non-small cell lung cancer (NSCLC) and diverse healthy tissues, we identified a subset of splicing junctions that is both tumor specific and shared across patients. We used HLA-I peptidomics to identify peptides encoded by tumor-specific junctions in primary NSCLC samples and lung tumor cell lines. Recurrent junction-encoded peptides were immunogenic in vitro, and CD8+ T cells specific for junction-encoded epitopes were present in tumors and tumor-draining lymph nodes from patients with NSCLC. We conclude that noncanonical splicing junctions between exons and TEs represent a source of recurrent, immunogenic tumor-specific antigens in patients with NSCLC.

Identifying CDC7 as a synergistic target of chemotherapy in resistant small-cell lung cancer via CRISPR/Cas9 screening

There is currently a lack of efficacious treatments for patients with chemo-resistant small-cell lung cancer (SCLC), leading to poor prognoses. We examined a chemo-resistant SCLC cell line using genome-wide CRISPR/Cas9 screening and identified serine/threonine kinase cell division cycle 7 (CDC7) as a potential synergistic target. Silencing CDC7 in chemo-resistant SCLC cells decreased the IC50 and improved the efficacy of chemotherapy. Based on the highest single agent model, the CDC7 inhibitor XL413 had a synergistic effect with both cisplatin and etoposide in chemo-resistant SCLC cells, but had no such effect in chemo-sensitive SCLC cells; the combination of XL413 and chemotherapy significantly inhibited cell growth. Western blot and flow cytometry showed that the combined treatments increased apoptosis, whereas XL413 alone had little effect on apoptosis. An analysis of cell cycle and cyclin protein levels indicated that the combination of XL413 and chemotherapy-induced G1/S phase arrest and DNA damage in chemo-resistant SCLC cells. Xenografted tumor and histoculture drug response assays using patient-derived xenografts showed that XL413 improved the efficacy of chemotherapy in vivo and with SCLC tissues. These results suggest that XL413 exerts a synergistic effect with chemotherapy on chemo-resistant SCLC.

UHRF1 plays an oncogenic role in small cell lung cancer.

Small cell lung cancer (SCLC) is a malignant tumor characterized by aggressiveness and dismal prognosis. The specific role of ubiquitin-like PHD and RING finger domain (UHRF1), a frequently overexpressed cancer-promoting gene in various tumors, is poorly understood in SCLC. Herein, we explored the potential carcinogenic role of UHRF1 in SCLC. First, public databases were used to analyze the expression of UHRF1 in SCLC, and tissue specimens in our center were examined to confirm the results while clinical outcomes were collected to analyze its relationship with UHRF1. Then, UHRF1 knockdown and overexpression cell lines were established to evaluate the carcinogenic function of UHRF1 in vitro and in vivo. The mechanism of the biological consequences was determined by co-inmunoprecipitation. Moreover, we also analyzed the influence of UHRF1 on cisplatin (DDP) sensitivity of SCLC. The expression of UHRF1 was significantly higher in SCLC tissues than in normal tissues, and high levels of UHRF1 suggested a poor prognosis for SCLC. Mechanistically, UHRF1 promoted SCLC growth through yes-associated protein 1 (YAP1). Specifically, UHRF1 bound to YAP1 and inhibited YAP1 ubiquitin degradation, thus stabilizing the YAP1 protein in SCLC cells. UHRF1 downregulation enhanced DDP sensitivity in SCLC cells and was correlated with a favorable prognosis in patients with SCLC treated with platinum-based chemotherapy. UHRF1 plays an oncogenic role in SCLC by modulating YAP1. Therefore, UHRF1 could be used as a biomarker to predict the prognosis of SCLC patients and serve as a potential therapeutic target for SCLC patients.

Molecular features and evolutionary trajectory of ASCL1+ and NEUROD1+ SCLC cells.

Small cell lung cancer (SCLC) is the most aggressive subtype of lung cancer without recognised morphologic or genetic heterogeneity. Based on the expression of four transcription factors, ASCL1, NEUROD1, POU2F3, and YAP1, SCLCs are classified into four subtypes. However, biological functions of these different subtypes are largely uncharacterised. We studied intratumoural heterogeneity of resected human primary SCLC tissues using single-cell RNA-Seq. In addition, we undertook a series of in vitro and in vivo functional studies to reveal the distinct features of SCLC subtypes. We identify the coexistence of ASCL1+ and NEUROD1+ SCLC cells within the same human primary SCLC tissue. Compared with ASCL1+ SCLC cells, NEUROD1+ SCLC cells show reduced epithelial features and lack EPCAM expression. Thus, EPCAM can be considered as a cell surface marker to distinguish ASCL1+ SCLC cells from NEUROD1+ SCLC cells. We further demonstrate that NEUROD1+ SCLC cells exhibit higher metastatic capability than ASCL1+ SCLC cells and can be derived from ASCL1+ SCLC cells. Our studies unveil the biology and evolutionary trajectory of ASCL1+ and NEUROD1+ SCLC cells, shedding light on SCLC tumourigenesis and progression.