EMT诱导肿瘤干细胞特性参与卵巢癌耐药的机制研究

Metastasis and chemo-resistance are the major reason which is responsible for the treatment failure and lead to the death of ovarian cancer patients. Epithelial-mesenchymal transition (EMT)) plays an important role in cancer metastasis. Advanced studies showed that cancer cells having double characteristic of EMT and stem cell line was the key point in tumor metastasis and chemo-resistance, EMT is closely related to cancer stem cells, the detailed molecular mechanism is not clear yet. In our present study, epithelial ovarian cell line is used as model, EMT is induced by EGF and TGF-β, investigate the change of EMT and identify the change of stem cells. The expression of transcription factors related to EMT, such as HIF-1α, Twist, Zeb1, Snail and Slug is detected. We try to elucidate if the ovarian cancer cells could obtain the character of cancer stem cells during cancer cells EMT, and whether this change participate in chemo-resistance. Based on the above findings, we try to explore the strategy using target EMT and disturb ovarian stem cells signal pathway to affect the cancer metastasis and chemo-resistance. The expression of EMT related transcription factors is knocked down by RNAi, and the EMT knock-down cell lines were implanted into nude mice to get the in vivo evidence.

转移及化疗耐药已成为卵巢癌患者治疗失败和死亡的主要原因。上皮间质转化(epithelial - mesenchymal transition, EMT)是肿瘤转移重要机制之一。最新的研究认为具有EMT和干细胞双重特性的癌细胞是肿瘤转移和耐药的关键，EMT和癌干细胞之间存在直接联系，但分子机制仍不清楚。本研究以上皮性卵巢癌细胞系为模型，通过EGF及TGFβ诱导EMT，观察EMT特征性改变、鉴定卵巢癌干细胞群的变化，并通过免疫荧光观察EMT及癌干细胞分子标志物的定位，观察化疗耐药，并检测包括HIF-1α、Twist、Zeb1、Snail和slug等EMT相关转录因子的表达；明确卵巢癌细胞发生EMT的同时是否可获得卵巢癌干细胞特性并参与耐药，阐明其可能的分子机制。通过RNA干扰靶向EMT相关转录因子的表达，并结合裸鼠体内移植瘤研究，探讨靶向EMT及卵巢癌干细胞信号通路的策略及对肿瘤转移及耐药的影

尽管癌症治疗近年来取得了一定的进展，但卵巢癌仍然是肿瘤治疗的挑战。最近的研究认为癌症干细胞和EMT的作用有关， EMT和干细胞双重特性的癌细胞是肿瘤转移和耐药的关键，但分子机制仍然不清楚。我们在研究中发现TGFβ及缺氧诱导卵巢癌细胞发生EMT 的同时诱导了细胞类干性特征，表现为提高细胞的自我修复能力及成瘤能力，提高了对顺铂和紫杉醇的耐药；尽管不同的卵巢癌细胞，由于来源的肿瘤类型不同， 发生EMT 可能通过不同的分子机制，但研究发现转录因子Slug是共有的EMT靶向分子，敲除EMT相关转录因子Slug抑制了TGFβ及缺氧诱导的卵巢癌细胞的干性特性，表现为细胞干性标志物的表达下调，细胞球形成能力减弱，细胞侵袭能力减弱，细胞增殖能力及成瘤能力减弱，对化疗药物的敏感性增强。在富集的细胞球中靶向敲除Slug也表现出细胞的干性减弱。本研究提供了TGFβ及缺氧诱导EMT 同时诱导细胞干性的新证据，并暗示靶向EMT 信号可能同时杀灭肿瘤干细胞，提高了化疗药物的敏感性.