Background/Objectives: Small cell lung cancer (SCLC) is one of the malignancies with the worst prognosis, and there have been no major breakthroughs in its treatment for a long time. The majority of patients are diagnosed at the extensive stage, where the only option is chemotherapy, and even the addition of immune checkpoint inhibitors results in only modest benefits. The characterization of the molecular mechanisms behind therapy resistance has relevance in finding novel therapeutic approaches. Previous studies showed the possibility of annexin A1’s (ANXA1) involvement in the immunosuppressive tumor microenvironment in SCLC, and there are studies showing the direct effects of ANXA1 modulation on cancer cell aggressiveness. Methods: We aimed to characterize the roles of ANXA1 expression using publicly available transcriptomic data, the RNA-seq-based predictive algorithms EPIC and ESTIMATE, and immunohistochemistry on patient samples. For the in vitro studies, we silenced ANXA1 expression with short hairpin RNA in three SCLC cell lines, measured the growth rate with the trypan blue exclusion assay, assessed the chemosensitivity to cisplatin and etoposide with the Presto BlueTMviability assay, and performed Western blots to assess changes in the levels of metabolic and mesenchymal markers and transcriptional drivers. Results: ANXA1-high tumors are associated with significantly increased immune infiltrates, stromality, and tumor-associated macrophages (TAMs). The ANXA1 protein is expressed on tumor cells and TAMs at the tissue level. ANXA1 silencing in H841 cells did not affect the growth rate; in SW1271 cells, shANXA1 cells grew significantly slower than shCTRL cells. Meanwhile, in H1048 cells, proliferation was significantly faster. Despite the different growth rates of the tested cell lines, ANXA1 silencing decreased the chemosensitivity to both cisplatin and etoposide in all three cell lines. Gene expression changes in mesenchymal markers, metabolic markers, dominant transcriptional drivers, and immune-relevant molecules were also characterized. Conclusions: This is the first comprehensive characterization of ANXA1 in SCLC to reveal its role in the tumor’s cell biology and the TME, aiming to boost further research in the field.
背景/目的：小细胞肺癌（SCLC）是预后最差的恶性肿瘤之一，其治疗长期未有重大突破。多数患者确诊时已处于广泛期，此时化疗成为唯一选择，即使联合免疫检查点抑制剂也仅能带来有限获益。阐明治疗抵抗背后的分子机制对探索新型治疗策略具有重要意义。既往研究表明膜联蛋白A1（ANXA1）可能参与SCLC免疫抑制性肿瘤微环境的形成，并有研究显示调控ANXA1可直接影响癌细胞侵袭性。方法：我们利用公开转录组数据、基于RNA-seq的预测算法EPIC和ESTIMATE，结合患者样本的免疫组化分析，系统研究ANXA1表达的作用机制。在体外实验中，通过短发夹RNA在三种SCLC细胞系中敲低ANXA1表达，采用台盼蓝拒染法测定细胞生长速率，使用Presto BlueTM活力检测法评估对顺铂和依托泊苷的化疗敏感性，并通过Western blot检测代谢标志物、间质标志物及转录驱动因子的水平变化。结果：ANXA1高表达肿瘤与显著增加的免疫浸润、基质成分及肿瘤相关巨噬细胞（TAMs）密切相关。组织水平检测显示ANXA1蛋白在肿瘤细胞和TAMs中均有表达。在H841细胞中敲低ANXA1不影响生长速率；SW1271细胞中shANXA1细胞生长显著慢于shCTRL细胞；而H1048细胞中增殖显著加快。尽管各细胞系生长速率存在差异，但在所有三种细胞系中敲低ANXA1均降低了对顺铂和依托泊苷的化疗敏感性。研究同时揭示了间质标志物、代谢标志物、关键转录驱动因子及免疫相关分子的基因表达变化特征。结论：本研究首次系统阐明了ANXA1在SCLC中的作用机制，揭示了其在肿瘤细胞生物学及肿瘤微环境中的关键角色，有望推动该领域的深入研究。
肿瘤(癌症)患者之家