FSIP2调控肾癌肿瘤干细胞特性促进血管生成拟态的作用机制

Cancer stem cell (CSC) imitating endothelial cells to form vasculogenic mimicry (VM) is a vital pathway for renal carcinoma blood supply yet it’s underlying mechanism remains unclear. Given the applicant’s previous study results, fibrous sheath interacting protein 2(FSIP2) is highly expressed in CD133+CSC. Knocking out FSIP2 significantly down-regulated the ratio of CD133+CSC cell, accompanied by down-regulation of VM key factors EphA2 and VE-cadherin. This study will validate the hypothesis that FSIP2 promotes VM by enhancing the stemness of renal cancer cells. First, we will verify the correlation between FSIP2 expression level and clinical indication of renal cancer in clinical samples. Second, we will study the effects of FSIP2, EphA2 and VE-cadherin on renal cancer CSC and VM by modulating their expression at the cellular level. Subsequently, the regulation mechanism of FSIP2 regulating EphA2 and VE-cadherin will be confirmed at the molecular level. Finally, the effect of FSIP2 on tumorigenesis, VM and metastasis of renal carcinoma CSC will be verified in vivo. This study will contribute to the understanding of the mechanism of renal cancer metastasis and may provide evidences for new therapeutic targets screening of renal cancer.

肿瘤干细胞（CSC）模仿内皮细胞参与血管生成拟态（VM）形成，是肾癌肿瘤血液供应的重要途径，但其调控机制尚不清楚。申请人前期发现纤维鞘相互作用蛋白2(FSIP2)在CD133+CSC中显著高表达，敲除FSIP2显著下调CD133+CSC细胞含量，且伴随VM关键因子EphA2和VE-cadherin下调。本研究拟验证FSIP2通过增强肾癌肿瘤干细胞特性进而促进VM这一假说：首先在临床样本中验证FSIP2表达水平与肾癌临床指征的相关性；其次在细胞水平上改变FSIP2、EphA2和VE-cadherin的表达研究其对肾癌CSC和VM的影响；再次从分子水平明确FSIP2调控EphA2和VE-cadherin的调控机理；最后在动物水平上验证FSIP2对肾癌CSC成瘤、VM及转移能力的影响。本研究将为肾癌转移机制和新靶点筛选提供实验依据。

纤维鞘相互作用蛋白2（fibrous sheath interacting protein 2, FSIP2）属于睾丸抗原家族，是一种新型生精细胞特异性蛋白，可能与精子发育和细胞有丝分裂有关。全外显子组测序显示，FSIP2 突变是精子鞭毛中多种形态异常的复发原因。目前，FSIP2 可在少数几种肿瘤中表达，比如睾丸生殖细胞瘤。全外显子组测序分析显示FSIP2 突变影响睾丸生殖细胞肿瘤的发生和发展。FSIP2 可能对癌症的发展和进展具有潜在影响。肾癌（Renal cell carcinoma，RCC）是常见的恶性肿瘤，且发病率近年有逐渐增加的趋势。RCC转移率、复发率高，对放化疗都不敏感，并具有多药耐药性，究其原因可能与是RCC干性存在有关。因此，鉴定和解析FSIP2在RCC生物学功能中的调控作用对RCC的治疗具有重要意义。.本研究中，我们发现纤维鞘相互作用蛋白2（fibrous sheath interacting protein 2，FSIP2）在CD133+CSC中显著高表达，敲除FSIP2显著下调CD133+CSC细胞含量，且伴随有血管生成拟态（vasculogenic mimicry，VM）关键因子EphA2和VE-cadherin下调。本研究中，我们通过一系列实验证实FSIP2通过增强RCC细胞特性进而促进VM这一假说：首先通过生信和我们单中心的临床样本中验证了FSIP2表达水平与RCC临床指征的相关性；其次我们在在细胞水平上改变FSIP2的表达研究其对RCC细胞和VM的影响；接下来我们又从分子水平进一步明确FSIP2调控RCC细胞功能的调控机理；最后，我们在动物水平上通过动物实验验证FSIP2对RCC细胞成瘤、VM及转移能力的影响。以上研究结果提示，FSIP2将成为RCC转移机制和药物筛选的新靶点。