Girnius Nomeda, Henstridge Aylin Z, Marks Benjamin, Yu Jeffrey K, Gray G Kenneth, Sander Chris, Zervantonakis Ioannis K, Luna Augustin
Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA.
Laboratory of Systems Pharmacology, Harvard Medical School, Boston, USA.
Breast Cancer Res. 2024 Dec 20;26(1):187. doi: 10.1186/s13058-024-01942-2.
Treatment options for triple-negative breast cancer (TNBC) are limited and patients face a poor prognosis. Here, we sought to identify drugs that target TNBC vulnerabilities and understand the biology underlying these responses. We analyzed the Broad Institute DepMap to identify recurrent TNBC vulnerabilities and performed a 45-compound screen on vulnerability-related pathways on a set of up to 8 TNBC cell lines. We identified a subset of cell lines with an ITGAV vulnerability and a differential sensitivity to cilengitide, an integrin inhibitor targeting ITGAV:ITGB3 and ITGAV:ITGB5. Next, we sought to understand cilengitide resistance and response biomarkers. Clinical trials targeting integrins continue enrolling patients, necessitating an understanding of how these drugs affect tumors.
We combined in vitro assays with computational approaches to systematically explore the differential sensitivity to cilengitide and resistance mechanisms. We tested an additional pan-ITGAV inhibitor (GLPG0187) to determine how generalizable our findings on cilengitide sensitivity might be to integrin inhibition. ITGB4, ITGA3, and ITGA6 knockdown experiments assessed the importance of integrin monomers in cell attachment during cilengitide treatment. Additionally, we explored the role of extracellular matrix (ECM) proteins in cilengitide response by performing cell replating experiments and by culturing on collagen, fibronectin, or laminin coated plates.
We discovered that cell-derived ECM modulates cilengitide sensitivity and exogenous fibronectin addition conferred resistance to all sensitive TNBC cell lines, though fibronectin expression did not correlate with sensitivity. Instead, elevated overall integrin protein levels, not specific integrins, in TNBC cells positively correlated with resistance. This suggested that high pan-integrin expression promotes cilengitide resistance. Thus, we tested cilengitide in six luminal breast cancer cell lines (which have low integrin levels); all were sensitive. Also, pan-ITGAV inhibitor, GLPG0187, showed the same sensitivity profile across our TNBC cell lines, suggesting our findings apply to other integrin inhibitors.
Integrin inhibitors are appealing candidates to pursue as anti-cancer drugs because they are generally well-tolerated, but their efficacy is mixed, possibly due to the absence of predictive markers. Cilengitide induces death in breast cancer cells with low integrin abundance, where complementary ECM promotes survival. Thus, integrin inhibition in breast cancer warrants further study.
三阴性乳腺癌（TNBC）的治疗选择有限，患者预后较差。在此，我们试图确定针对TNBC脆弱性的药物，并了解这些反应背后的生物学机制。我们分析了布罗德研究所的DepMap以确定复发性TNBC脆弱性，并对一组多达8种TNBC细胞系中与脆弱性相关的通路进行了45种化合物的筛选。我们鉴定出一组对ITGAV有脆弱性且对西仑吉肽（一种靶向ITGAV:ITGB3和ITGAV:ITGB5的整合素抑制剂）具有不同敏感性的细胞系。接下来，我们试图了解西仑吉肽耐药性和反应生物标志物。针对整合素的临床试验仍在招募患者，因此有必要了解这些药物如何影响肿瘤。
我们将体外试验与计算方法相结合，系统地探索对西仑吉肽的不同敏感性和耐药机制。我们测试了另一种泛ITGAV抑制剂（GLPG0187），以确定我们关于西仑吉肽敏感性的发现对整合素抑制的普遍适用性。ITGB4、ITGA3和ITGA6基因敲低实验评估了整合素单体在西仑吉肽治疗期间细胞附着中的重要性。此外，我们通过进行细胞重铺板实验以及在胶原蛋白、纤连蛋白或层粘连蛋白包被的平板上培养，探索了细胞外基质（ECM）蛋白在西仑吉肽反应中的作用。
我们发现细胞衍生的ECM调节西仑吉肽敏感性，添加外源性纤连蛋白可使所有敏感的TNBC细胞系产生耐药性，尽管纤连蛋白表达与敏感性无关。相反，TNBC细胞中整体整合素蛋白水平升高（而非特定整合素）与耐药性呈正相关。这表明高泛整合素表达促进西仑吉肽耐药。因此，我们在六种管腔型乳腺癌细胞系（整合素水平低）中测试了西仑吉肽；所有细胞系均敏感。此外，泛ITGAV抑制剂GLPG0187在我们的TNBC细胞系中显示出相同的敏感性特征，表明我们的发现适用于其他整合素抑制剂。
整合素抑制剂作为抗癌药物很有吸引力，因为它们通常耐受性良好，但其疗效参差不齐，可能是由于缺乏预测性标志物。西仑吉肽可诱导整合素丰度低的乳腺癌细胞死亡，而互补的ECM可促进其存活。因此，乳腺癌中的整合素抑制值得进一步研究。
