PDF(Pubmed)
Abstract：
Estrogen receptor positive (ER+) breast cancer (BCa) accounts for the highest proportion of breast cancer-related deaths. While endocrine therapy is highly effective for this subpopulation, endocrine resistance remains a major challenge and the identification of novel targets is urgently needed. Previously, we have shown that Semaphorin 3C (SEMA3C) is an autocrine growth factor that drives the growth and treatment resistance of various cancers, but its role in breast cancer progression and endocrine resistance is poorly understood. Here, we report that SEMA3C plays a role in maintaining the growth of ER+ BCa cells and is a novel, tractable therapeutic target for the treatment of ER+ BCa patients. Analyses of publicly available clinical datasets indicate that ER+ BCa patients express significantly higher levels of SEMA3C mRNA than other subtypes. Furthermore, SEMA3C mRNA expression was positively correlated with ESR1 mRNA expression. ER+ BCa cell lines (MCF7 and T47D) expressed higher levels of SEMA3C mRNA and protein than a normal mammary epithelial MCF10A cell line. ER siRNA knockdown was suppressed, while dose-dependent beta-estradiol treatment induced SEMA3C expression in both MCF7 and T47D cells, suggesting that SEMA3C is an ER-regulated gene. The stimulation of ER+ BCa cells with recombinant SEMA3C activated MAPK and AKT signaling in a dose-dependent manner. Conversely, SEMA3C silencing inhibited Estrogen Receptor (ER) expression, MAPK and AKT signaling pathways while simultaneously inducing apoptosis, as monitored by flow cytometry and Western blot analyses. SEMA3C silencing significantly inhibited the growth of ER+ BCa cells, implicating a growth dependency of ER+ BCa cells on SEMA3C. Moreover, the analysis of tamoxifen resistant (TamR) cell models (TamC3 and TamR3) showed that SEMA3C levels remain high despite treatment with tamoxifen. Tamoxifen-resistant cells remained dependent on SEMA3C for growth and survival. Treatment with B1SP Fc fusion protein, a SEMA3C pathway inhibitor, attenuated SEMA3C-induced signaling and growth across a panel of tamoxifen sensitive and resistant ER+ breast cancer cells. Furthermore, SEMA3C silencing and B1SP treatment were associated with decreased EGFR signaling in TamR cells. Here, our study implicates SEMA3C in a functional role in ER+ breast cancer signaling and growth that suggests ER+ BCa patients may benefit from SEMA3C-targeted therapy.
摘要：
雌激素受体阳性（ER+）乳腺癌（BCa）占乳腺癌相关死亡的比例最高。虽然内分泌治疗对这个亚群非常有效，内分泌抵抗仍然是一项重大挑战,因此迫切需要鉴定新的靶标.以前,我们已经证明，信号素3C（SEMA3C）是一种自分泌生长因子，驱动各种癌症的生长和治疗抗性，但其在乳腺癌进展和内分泌抵抗中的作用却知之甚少。这里,我们报道，SEMA3C在维持ER+BCa细胞的生长中起作用，治疗ER+BCa患者的可处理的治疗目标。公开可用的临床数据集的分析表明,ER+BCa患者比其他亚型表达显著更高水平的SEMA3CmRNA。此外，SEMA3CmRNA表达与ESR1mRNA表达呈正相关。ERBCa细胞系（MCF7和T47D）比正常乳腺上皮MCF10A细胞系表达更高水平的SEMA3CmRNA和蛋白质。ERsiRNA敲低被抑制，而剂量依赖性β-雌二醇处理诱导MCF7和T47D细胞中SEMA3C的表达，这表明SEMA3C是ER调节基因。用重组SEMA3C刺激ER+BCa细胞以剂量依赖性方式激活MAPK和AKT信号传导。相反，SEMA3C沉默抑制雌激素受体（ER）表达，MAPK和AKT信号通路同时诱导细胞凋亡,通过流式细胞术和蛋白质印迹分析监测。SEMA3C沉默显著抑制ER+BCa细胞的生长,暗示ER+BCa细胞对SEMA3C的生长依赖性。此外，对他莫昔芬抗性(TamR)细胞模型(TamC3和TamR3)的分析显示,尽管用他莫昔芬治疗,SEMA3C水平仍然很高.他莫昔芬抗性细胞的生长和存活仍然依赖于SEMA3C。用B1SPFc融合蛋白治疗，一种SEMA3C途径抑制剂，在一组他莫昔芬敏感和耐药的ER+乳腺癌细胞中，SEMA3C诱导的信号传导和生长减弱。此外，SEMA3C沉默和B1SP处理与TamR细胞中降低的EGFR信号相关。这里,我们的研究提示SEMA3C在ER+乳腺癌信号传导和生长中发挥功能作用,提示ER+BCa患者可能受益于SEMA3C靶向治疗.
