Small Cell Lung Cancer Metastasis 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.

PROTAC EZH2 degrader-1 overcomes the resistance of podophyllotoxin derivatives in refractory small cell lung cancer with leptomeningeal metastasis

BackgroundLeptomeningeal metastasis (LM) of small cell lung cancer (SCLC) is a highly detrimental occurrence associated with severe neurological disorders, lacking effective treatment currently. Proteolysis-targeting chimeric molecules (PROTACs) may provide new therapeutic avenues for treatment of podophyllotoxin derivatives-resistant SCLC with LM, warranting further exploration.MethodsThe SCLC cell line H128 expressing luciferase were mutated by MNNG to generate H128-Mut cell line. After subcutaneous inoculation of H128-Mut into nude mice, H128-LM and H128-BPM (brain parenchymal metastasis) cell lines were primarily cultured from LM and BPM tissues individually, and employed to in vitro drug testing. The SCLC-LM mouse model was established by inoculating H128-LM into nude mice via carotid artery and subjected to in vivo drug testing. RNA-seq and immunoblotting were conducted to uncover the molecular targets for LM.ResultsThe SCLC-LM mouse model was successfully established, confirmed by in vivo live imaging and histological examination. The upregulated genes included EZH2, SLC44A4, VEGFA, etc. in both BPM and LM cells, while SLC44A4 was particularly upregulated in LM cells. When combined with PROTAC EZH2 degrader-1, the drug sensitivity of cisplatin, etoposide (VP16), and teniposide (VM26) for H128-LM was significantly increased in vitro. The in vivo drug trials with SCLC-LM mouse model demonstrated that PROTAC EZH2 degrader-1 plus VM26 or cisplatin/ VP16 inhibited H128-LM tumour significantly compared to VM26 or cisplatin/ VP16 alone (P < 0.01).ConclusionThe SCLC-LM model effectively simulates the pathophysiological process of SCLC metastasis to the leptomeninges. PROTAC EZH2 degrader-1 overcomes chemoresistance in SCLC, suggesting its potential therapeutic value for SCLC LM.

Abstract 1438: Investigating the roles of EMT in small cell lung cancer tumorigenesis and chemoradiation response

Abstract In this study, we investigated the contributions of the epithelial-mesenchymal transition (EMT) program to small cell lung cancer (SCLC) tumorigenesis and chemoradiation (CRT) response. SCLC is a highly aggressive and deadly neuroendocrine malignancy. Two major factors that contribute to the high mortality of SCLC are (1) early metastasis and (2) rapid development of therapy resistance. Recent research suggests upregulation of EMT and the EMT transcription factor Twist1 correlated with accelerated tumor progression and CRT resistance in SCLC. Due to the lack of suitable animal models, the causal relationship between the EMT program and SCLC tumorigenesis and therapy response has not been rigorously investigated. To this end, we have generated a novel genetically engineered mouse model (GEMM) termed RPGT (Rb1Flox; Trp53Flox; ROSA26LSL-rtTA-IRES-EGFP; Twist1-TetO7-Luc). The RPGT GEMM enables the generation of autochthonous SCLC tumors after induction with Cre recombinase adenovirus. By withdrawing or providing doxycycline to mice, we can control Twist1 expression to activate or inactivate EMT in tumors. Upon characterizing mouse tumor samples with histological and molecular analyses, we observed that both control (no Twist1 overexpression) and Twist1-overexpressing RPGT mice developed neuroendocrine SCLC tumors. While SCLC-A was the predominant subtype in both cohorts, RPGT tumors exhibited more heterogeneity. Importantly, although no difference in tumorigenesis was observed, Twist1 overexpression dramatically increased the metastatic incidence in RPGT (87-100%) compared to control (25-50%) animals, indicating an important role of EMT in SCLC dissemination. Furthermore, transcriptomic profiling of primary tumors and matching metastases in RPGT mice revealed downregulation of Twist1 and EMT in metastases, suggesting that EMT suppression was necessary for metastatic outgrowth. To evaluate the impact of EMT activation on SCLC sensitivity to CRT, we performed in vitro viability assays on primary tumor cell lines established from RPGT tumors. We found that repressing Twist1 expression enhanced SCLC susceptibility to CRT. To validate these results in vivo, we treated RPGT mice with vs. without Twist1 overexpression with CRT. Consistent with our in vitro results, our in vivo data indicated that Twist1 overexpression promoted CRT resistance in SCLC tumors. Overall, our data suggest that the EMT program plays an important role in SCLC differentiation, metastasis, and resistance against chemo-radiotherapy. Citation Format: Triet Nguyen, Jinhee Chang, Kathleen Gabrielson, Amol Shetty, Yang Song, Audrey Lafargue, Shreya Jagtap, Danielle Council, Aaron Chan, Dipanwita Dutta Chowdhury, Muhammad Ajmal Khan, Nick Connis, Francesca Carrieri, Eddie Imada, Daniel Sforza, Eric Gardner, Christopher McFarland, Luigi Marchionni, Mohammad Rezaee, Christine Hann, Phuoc Tran. Investigating the roles of EMT in small cell lung cancer tumorigenesis and chemoradiation response [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 1438.

Predictive importance of systemic inflammation response index in de novo brain metastatic small cell lung cancer patients

Aims: The subtype of lung cancer, known as small cell lung cancer (SCLC), tends to have a highly fatal course, especially in advanced stages. In particular, the overall survival durations further decrease in cases of brain metastases in SCLC. There is increasing evidence for the role of systemic inflammation parameters in predicting cancer prognosis, and they appear likely to become potential target markers for clinical treatments in the future. We aimed to evaluate the systemic inflammation response index (SIRI), a novel inflammatory laboratory marker that could predict long-term survival and serve as a potential target marker for clinical treatment, in patients with de novo brain metastatic small cell lung carcinoma (DNBM SCLC)."&#x0D; Methods: Clinicopathological features of adult patients diagnosed with DNBM SCLC were recorded from the patient registry of the hospital. Patients without medical records were not included in the study. Investigations were carried out to assess the prognostic effect of the SIRI parameter in predicting the 12-month overall survival (OS12) in DNBM SCLC patients, by determining a cut-off value and conducting appropriate statistical analyses, considering p-values (

Plasma hepatocyte growth factor as a noninvasive biomarker in small cell lung cancer

BackgroundHepatocyte growth factor (HGF) is a peptide-containing multifunctional cytokine, which is overexpressed and/or activated in multiple malignancies and is reported to be associated with tumor development and inferior survival. At present, the role of HGF in small cell lung cancer (SCLC) has not been fully explored yet.Materials and methodsThe expression of HGF and its value in predicting survival in SCLC were explored from GEO database and in pan-cancer analysis. Furthermore, we detected the expression of HGF using tumor tissue and paired plasma samples from a validation cohort of 71 SCLC patients at our institute. Correlation between tumor and plasma HGF expression and the prognostic values were analyzed.ResultsGEO database analysis revealed that tumor tissue had lower HGF expression than paired normal tissue in SCLC. At our institute, immunohistochemical staining showed negative expression of HGF in tumor tissue of SCLC at our institute (47/47, 100%). The average baseline plasma HGF was 1.28 (range,0.42–4.35) ng/ml. However, plasma HGF was higher in SCLC patients with patients with N3, M1, liver metastasis (LM) and bone metastasis (BM) disease compared with those N0 − 2 (1.25 vs. 1.75 ng/mL, P = 0.000), M0 (1.26 vs. 1.63 ng/mL, P = 0.003), non-LM (1.32 vs. 2.06 ng/mL, P = 0.009), and non-BM (1.35 vs. 1.77 ng/mL, P = 0.047), respectively. Multivariate analysis revealed plasma HGF was an independent predictor for LM and prognostic factor of OS.ConclusionOur results revealed that plasma HGF rather than tumor HGF exhibited a potential role in predicting metastasis and survival in SCLC. Plasma HGF might be used as a non-invasive detecting and monitoring tool for 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.

MDM2-mediated Inhibitory Effect of Arsenic Trioxide on Small Cell Lung Cancer Cell Line by Degrading Mutant p53.

Small cell lung cancer (SCLC) is featured by a high TP53 mutant rate. Our previous research found that arsenic trioxide (As2O3) could significantly inhibit the growth and metastasis of SCLC. Studies have shown that the degradation of mutant p53 mediated by murine double minute 2 (MDM2) can be induced by As2O3, which probably contributes to the inhibition of SCLC, but the detailed mechanism is still unclear. We aimed to testify that As2O3 can inhibit the growth of SCLC cells by degrading mutant p53 protein via binding to MDM2. CCK-8 assay, cell cycle analysis, and western blot of apoptosis markers were used to evaluate the inhibitory effect of As2O3 on NCI-H446 cells (containing mutant p53) and NCI-H1299 cells (p53 null). The effects of As2O3 on p53 and its downstream proteins were identified by western blot using mut-p53-knockdown and overexpressed cell models. MDM2-knockdown cell models were constructed, and western blot, co-IP of mut-p53, and ubiquitin were carried out to explore the mediating effect of MDM2 in As2O3 induced mut-p53 degradation. As2O3 inhibited proliferation and induced cell cycle arrest and apoptosis of SCLC cells in a dose- and timedependent manner. After mut-p53 knockdown or overexpressed, the inhibitory effect of As2O3 was dampened or enhanced. Additionally, As2O3-induced mut-p53 ubiquitination was significantly weakened after MDM2 knockdown. As2O3 could inhibit SCLC cells by inhibiting proliferation and inducing cell cycle arrest and apoptosis. These inhibitory effects were achieved at least in part by upregulating MDM2, which, in turn, promotes ubiquitination and degradation of mut-p53.

Synchronous occurrence of small cell lung cancer and primary rectal dedifferentiated liposarcoma with osteosarcomatous differentiation: A rare case report.

Rectal dedifferentiated liposarcoma (DDL) and DDL with osteosarcomatous differentiation both are extremely unwonted. In addition, there are no reports of simultaneous DDL with osteosarcoma differentiation with small cell lung cancer (SCLC) to date. Therefore, it is imperative to alert clinicians and pathologists to this extremely rare and instructive synchronous tumor. The patient was a 63-year-old male who presented with intermittent hematochezia and a swelling in the anus. Irregular masses were found on computed tomography (CT) examinations of the chest and abdomen respectively. The final diagnosis of synchronous occurrence of SCLC and primary rectal DDL with osteosarcomatous differentiation was established by radiological, histological, immunohistochemical and molecular findings. The patient underwent a puncture biopsy of the right lung mass and a complete resection of the rectal mass. The patient abandoned treatment, and multiple SCLC metastases appeared multiple metastasis 8 months after the operation. In the end, he expired suddenly due to severe cerebral hemorrhage caused by brain SCLC metastasis. DDL with osteosarcoma differentiation is infrequent, and its accurate diagnosis is based on morphology, immunohistochemistry and the necessary molecular tests. In rare cases, DDL occurs concurrently with other malignancies and and will be a challenge for pathologists and clinicians at this time. Accordingly, a comprehensive examination to identify possible synchronous tumors is very important in clinical practice.

YAP silencing by RB1 mutation is essential for small-cell lung cancer metastasis

Small cell lung cancer (SCLC) is highly lethal due to its prevalent metastasis. Most SCLCs have inactivating mutations in TP53 and RB1. We find that loss of YAP expression is key for SCLC cells to acquire rapid ameboid migration and high metastatic potential. YAP functions through its target genes CCN1/CCN2 to inhibit SCLC ameboid migration. RB1 mutation contributes to YAP transcriptional silencing via E2F7, which recruits the RCOR co-repressor complex to YAP promoter. We discover that benzamide family HDAC inhibitors stimulate YAP expression by inhibiting the RCOR-HDAC complex, thereby suppressing SCLC metastasis and improving survival in a mouse model. Our study unveils the molecular and cellular basis underlying SCLC’s high metastatic potential, the previously unrecognized role of YAP in suppressing ameboid migration and tumor metastasis, and the mechanism of YAP transcription regulation involving E2F7, RCOR, and Sin3 HDAC. This study reveals a therapeutic potential of benzamides for SCLC treatment.

[Stereotactic radiosurgery for brain metastases in small-cell lung cancer?]

[Stereotactic radiosurgery for brain metastases in small-cell lung cancer?]

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.

Metastasis of small cell lung carcinoma to the appendix: A case report and literature review

Small cell lung cancer (SCLC) is an aggressive tumor with rapid growth and metastasis. Common sites of metastasis include lymph nodes, adrenal glands, liver, bone, and brain, while gastrointestinal metastasis is less and appendicular metastasis is much rarer. Here, we reported a rare case of appendiceal metastasis from small cell lung cancer presented with acute gangrenous perforated appendicitis, periappendiceal abscess and retroperitoneal abscess. The patient, a 63-year-old male, was diagnosed as small-cell lung cancer due to cough, expectoration and blood in sputum. After chemotherapy, local radiotherapy and whole brain prophylactic radiotherapy, the disease progressed continuously and recurred 1 year later, then presented with acute gangrenous perforated appendicitis combined with periappendiceal abscess and retroperitoneal abscess 2 years later. Histopathological and immunohistochemical findings after appendectomy suggested malignant metastasis of small cell lung cancer. Therefore, in the diagnosis and treatment of SCLC cases, SCLC metastasis occurs not only in the common lymph nodes, kidney, adrenal gland, brain, liver, etc., but also in the appendix. This report is expected to provide new guidance for the diagnosis and treatment of such cases.

Unilateral, Sectoral Retinal Metastasis of Small-Cell Lung Cancer Mimicking Viral Retinitis.

To report a case of unilateral, sectoral retinal metastasis of small-cell lung cancer (SCLC) that mimicked cytomegalovirus (CMV) retinitis. Case report. A 48-year-old woman presented with a four-week history of a visual field loss in her right eye. She had a past medical history of extensive-stage SCLC with brain metastasis, stable on maintenance atezolizumab for two years. On initial presentation, she was diagnosed with CMV retinitis. No improvement was observed with 4 weeks of oral valganciclovir. Upon referral for a second opinion, her fundus exam appeared compatible with CMV retinitis, and anterior chamber tap for polymerase chain reaction for viral etiologies was performed followed by intravitreal and intravenous ganciclovir without improvement. She was referred for a third opinion, where diagnostic vitrectomy with vitreous and retinal biopsies were consistent with SCLC metastatic to the retina. The patient underwent enucleation of the right eye for definitive pathologic analysis and subsequently was started on additional systemic chemotherapy. Retinal metastases are exceedingly rare, particularly retinal metastasis of SCLC. Retinal metastasis should be considered in patients initially diagnosed with viral retinitis who fail to improve despite antiviral therapy, particularly if they have a known history of malignancy. Furthermore, retinal metastasis of SCLC potentially could be misdiagnosed histopathologically as retinoblastoma if the patient's history is unknown and appropriate immunohistochemical stains are not performed.

Involvement of Epithelial-Mesenchymal Transition Genes in Small Cell Lung Cancer Phenotypic Plasticity.

Small cell lung cancer (SCLC) is an aggressive cancer recalcitrant to treatment, arising predominantly from epithelial pulmonary neuroendocrine (NE) cells. Intratumor heterogeneity plays critical roles in SCLC disease progression, metastasis, and treatment resistance. At least five transcriptional SCLC NE and non-NE cell subtypes were recently defined by gene expression signatures. Transition from NE to non-NE cell states and cooperation between subtypes within a tumor likely contribute to SCLC progression by mechanisms of adaptation to perturbations. Therefore, gene regulatory programs distinguishing SCLC subtypes or promoting transitions are of great interest. Here, we systematically analyze the relationship between SCLC NE/non-NE transition and epithelial to mesenchymal transition (EMT)-a well-studied cellular process contributing to cancer invasiveness and resistance-using multiple transcriptome datasets from SCLC mouse tumor models, human cancer cell lines, and tumor samples. The NE SCLC-A2 subtype maps to the epithelial state. In contrast, SCLC-A and SCLC-N (NE) map to a partial mesenchymal state (M1) that is distinct from the non-NE, partial mesenchymal state (M2). The correspondence between SCLC subtypes and the EMT program paves the way for further work to understand gene regulatory mechanisms of SCLC tumor plasticity with applicability to other cancer types.

Study on the Biological Function of Abemecilib in Inhibiting the Proliferation, Invasion and
Migration of Small Cell Lung Cancer with High c-Myc Expression

Small cell lung cancer (SCLC) with high c-Myc expression is prone to relapse and metastasis, leading to extremely low survival rate. Cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitor Abemaciclib plays a key role in the treatment of tumors, but the effects and mechanisms on SCLC remain unclear. This study was to analyze the effect and molecular mechanism of Abemaciclib in inhibiting proliferation, migration and invasion of SCLC with high c-Myc expression, with a view to expanding a new direction for reducing the recurrence and metastasis. Proteins interacting with CDK4/6 were predicted using the STRING database. The expressions of CDK4/6 and c-Myc in 31 cases of SCLC cancer tissues and paired adjacent normal tissues were analyzed by immunohistochemistry. The effects of Abemaciclib on the proliferation, invasion and migration of SCLC were detected by CCK-8, colony formation assay, Transwell and migration assay. Western blot was used to detect the expressions of CDK4/6 and related transcription factors. Flow cytometry was used to analyze the effects of Abemaciclib on the cell cycle and checkpoint of SCLC. The expression of CDK4/6 was associated with c-Myc by STRING protein interaction network. c-Myc can directly modalize achaete-scute complex homolog 1 (ASCL1), neuronal differentiation 1 (NEUROD1) and Yes-associated protein 1 (YAP1). Moreover, CDK4 and c-Myc regulate the expression of programmed cell death ligand 1 (PD-L1). Immunohistochemistry showed that the expressions of CDK4/6 and c-Myc in cancer tissues were higher than those in adjacent tissues(P<0.0001). CCK-8, colony formation assay, Transwell and migration assay verified that Abemaciclib could effectively inhibit the proliferation, invasion and migration of SBC-2 and H446OE(P<0.0001). Western blot analysis further showed that Abemaciclib not only inhibited CDK4 (P<0.05) and CDK6 (P<0.05), but also affected c-Myc (P<0.05), ASCL1 (P<0.05), NEUROD1 (P<0.05) and YAP1 (P<0.05), which are related to SCLC invasion and metastasis. Flow cytometry showed that Abemaciclib not only inhibited the cell cycle progression of SCLC cells (P<0.0001), but also significantly increased PD-L1 expression on SBC-2 (P<0.01) and H446OE (P<0.001). Abemaciclib significantly inhibits the proliferation, invasion, migration and cell cycle progression of SCLC by inhibiting the expressions of CDK4/6, c-Myc, ASCL1, YAP1 and NEUROD1. Abemaciclib can also increase the expression of PD-L1 in SCLC.

Potential Avenues for Exosomal Isolation and Detection Methods to Enhance Small-Cell Lung Cancer Analysis.

Around the world, lung cancer has long been the main factor in cancer-related deaths, with small-cell lung cancer (SCLC) being the deadliest form of lung cancer. Cancer cell-derived exosomes and exosomal miRNAs are considered promising biomarkers for diagnosing and prognosis of various diseases, including SCLC. Due to the rapidity of SCLC metastasis, early detection and diagnosis can offer better diagnosis and prognosis and therefore increase the patient's chances of survival. Over the past several years, many methodologies have been developed for analyzing non-SCLC-derived exosomes. However, minimal advances have been made in SCLC-derived exosome analysis methodologies. This Review discusses the epidemiology and prominent biomarkers of SCLC. Followed by a discussion about the effective strategies for isolating and detecting SCLC-derived exosomes and exosomal miRNA, highlighting the critical challenges and limitations of current methodologies. Finally, an overview is provided detailing future perspectives for exosome-based SCLC research.

Slit2/Robo1 signaling inhibits small-cell lung cancer by targeting β-catenin signaling in tumor cells and macrophages.

Small-cell lung cancer (SCLC) is an aggressive neuroendocrine subtype of lung cancer with poor patient prognosis. However, the mechanisms that regulate SCLC progression and metastasis remain undefined. Here, we show that the expression of the slit guidance ligand 2 (SLIT2) tumor suppressor gene is reduced in SCLC tumors relative to adjacent normal tissue. In addition, the expression of the SLIT2 receptor, roundabout guidance receptor 1 (ROBO1), is upregulated. We find a positive association between SLIT2 expression and the Yes1 associated transcriptional regulator (YAP1)-expressing SCLC subtype (SCLC-Y), which shows a better prognosis. Using genetically engineered SCLC cells, adenovirus gene therapy, and preclinical xenograft models, we show that SLIT2 overexpression or the deletion of ROBO1 restricts tumor growth in vitro and in vivo. Mechanistic studies revealed significant inhibition of myeloid-derived suppressor cells (MDSCs) and M2-like tumor-associated macrophages (TAMs) in the SCLC tumors. In addition, SLIT2 enhances M1-like and phagocytic macrophages. Molecular analysis showed that ROBO1 knockout or SLIT2 overexpression suppresses the transforming growth factor beta 1 (TGF-β1)/β-catenin signaling pathway in both tumor cells and macrophages. Overall, we find that SLIT2 and ROBO1 have contrasting effects on SCLC tumors. SLIT2 suppresses, whereas ROBO1 promotes, SCLC growth by regulating the Tgf-β1/glycogen synthase kinase-3 beta (GSK3)/β-catenin signaling pathway in tumor cells and TAMs. These studies indicate that SLIT2 could be used as a novel therapeutic agent against aggressive SCLC.

The postoperative prognosis of skip-N2 metastasis is favorable in small-cell lung carcinoma patients with pathological N2 classification: a propensity-score-adjusted retrospective multicenter study.

The study on skip-N2 metastasis in small-cell lung cancer (SCLC) is lacking. Therefore, this study aimed to explore the prognostic significance of skip-N2 metastasis based on a multicenter cohort. We collected 176 SCLC patients with pathological categories T1-4N1-2M0 from four hospitals in China. Survival curves were drawn through the Kaplan-Meier method and compared by the log-rank test. The Cox regression method was used to calculate the hazard ratio (HR) and 95% confidence interval of the characteristics for cancer-specific survival (CSS). Two propensity-score methods were used to reduce the bias, including the inverse probability of treatment weighting (IPTW) and propensity-score matching (PSM). This multicenter database included 64 pN1 patients, 63 non-skip-N2 cases, and 49 skip-N2 cases. Skip-N2 and the non-skip-N2 patients had gap CSS rates (skip-N2 no versus yes: 41.0% versus 62.0% for 1-year CSS, 32.0% versus 46.0% for 2-year CSS, and 20.0% versus 32.0% for 3-year CSS). After PSM, there were 32 pairs of patients to compare survival differences between N2 and skip-N2 diseases, and 34 pairs of patients to compare prognostic gaps between N1 and skip-N2 diseases, respectively. The results of IPTW and PSM both suggested that skip-N2 cases had better survival outcomes than the non-skip-N2 cases (IPTW-adjusted HR = 0.578; PSM-adjusted HR = 0.510; all log-rank p < 0.05). Besides, the above two analytic methods showed no difference in prognoses between pN1 and skip-N2 diseases (all log-rank p > 0.05). Skip-N2 patients were confirmed to have a better prognosis than non-skip-N2 patients. Besides, there was no survival difference between pN1 and skip-N2 cases. Therefore, we propose that the next tumor-node-metastasis staging system needs to consider the situation of skip metastasis with lymph nodes in SCLC.

NLRP6 is required for cancer-derived exosome-modified macrophage M2 polarization and promotes metastasis in small cell lung cancer

Metastasis remains the primary cause of small cell lung cancer (SCLC)-related deaths. Growing evidence links tumor metastasis with a pre-metastatic microenvironment characterized by an anti-inflammatory response, immunosuppression, and the presence of tumor-derived exosomes. To clarify the relationships among these factors in SCLC, we analyzed SCLC patient samples as well as a mouse model. Among the infiltrating immune cells, our study focused on the tumor-associated macrophages (TAMs), that are well-known to promote tumor progression and metastasis. We found that high expression of the alternatively activated (M2) TAM marker, CD206+ was associated clinically with a poorer prognosis and metastasis state in patients with SCLC. Moreover, infiltrating macrophages (MØ) were found in the metastatic foci of an SCLC mouse model. Additionally, we observed dominant switching to M2 phenotype, accompanied by increased NLRP6 expression. Since tumor-derived exosomes are the key links between the tumor and its immune microenvironment, we further investigated whether SCLC-derived exosomes contributed to the MØ phenotype switch. Our findings showed for the first time that SCLC-derived exosomes induce the M2 switch via the NLRP6/NF-κB pathway, and thus, promote SCLC metastasis in vitro and in vivo. Collectively, these results indicate a novel mechanism by which SCLC-derived exosomes induce immunosuppression of distant MØ to promote systemic metastasis by activating NLRP6. Here, we highlight the close relationship between the tumor-derived exosomes, inflammasomes and immune microenvironment in SCLC metastasis.

The prognostic risk stratification model for metastatic small-cell lung cancer: An analysis of the SEER database.

Distant metastases of small-cell lung cancer (DM-SCLC) is an important factor in the selection of treatment strategies. In this study, we established a nomogram to predict DM-SCLC and determine the benefit of radiotherapy (RT) for DM-SCLC. We analyzed DM-SCLC prognosis based on surveillance, epidemiology, and end result database (SEER) data. A comprehensive and practical nomogram that predicts the overall survival (OS) of DM-SCLC was constructed and the results were compared with the 7th edition of the American Joint Committee on Cancer (AJCC) TNM stage system. A concordance index (C-index) and receiver operating characteristic plot were generated to evaluate the nomogram discrimination. The calibration was evaluated with a calibration plot, and its effectiveness was evaluated by a decision curve analysis (DCA). A score was assigned to each variable, and a total score was established for the risk stratification model. A total of 13,403 DM-SCLC patients were included. Eight characteristic variables were identified as independent prognostic variables. The C-index of the validation and training cohorts was 0.716 and 0.734, respectively. The area under the receiver operating characteristic curve (AUC) values of the nomogram used to predict 1-, 2-, and 3-year OS were 0.751, 0.744, and 0.786 in the validation cohorts (0.761, 0.777, 0.787 in the training cohorts), respectively. The calibration curve of 1-, 2-, 3-year survival rates showed that the prediction of the nomogram was in good agreement with the actual observation. The nomogram exhibited higher clinical utility after evaluation with the 1-, 2-, 3-year DCA compared with the AJCC stage system. A predictive nomogram and risk stratification model have been constructed to evaluate the prognosis of DM-SCLC effectively and accurately. This nomogram may provide a reference for prognosis stratification and treatment decisions.