循环肿瘤细胞高表达基因TGFBR2在鼻咽癌远处转移中的功能研究

Nasopharyngeal carcinoma (NPC) is endowed with a highly invasive metastatic potential, and hematogenous dissemination is a principal pattern of distant metastasis in NPC. By performing whole exon sequencing we found that the mutations presented more frequently in circulating tumor cells (CTCs) as compared to the primary-site tumor cells. Meanwhile, RNA chip revealed significantly different expression profiles between CTCs and primary tumors in NPC, and TGFBR2 was relatively highly expressed in CTCs, which presumably is associated with the self-renewal and phenotypic change to obtain higher capacity of invasion and metastasis in NPC cells. Our proposed study is designed to characterize the metastasis-relevant functions by determining the effects of overexpression or silencing of TGFBR2 on cell migration and invasion abilities in NPC cell lines in vitro. In addition, high-throughput protein chip screening is employed to identify the relevant functional molecular regulated by TGFBR2. Effects of TGFBR2 expression in CTCs on hematogenous dissemination and distant colonization were examined in vivo. Moreover, the clinical significant of TGFBR2 expression level in CTCs for risk of metastasis and prognosis in NPC is explored by follow-up study. Our study aims to clarify the role of TGFBR2 abnormally expressed in CTCs plays in hematogenous distant metastasis, and attempt to identify novel therapeutic targets for hematogenous distant metastasis in NPC.

鼻咽癌具有高度的侵袭转移倾向，其中血行播散是鼻咽癌远处转移的主要方式。通过全外显子测序我们发现，相较于原发灶外显子突变更为频发于鼻咽癌循环肿瘤细胞(CTCs)，而RNA表达芯片显示CTCs具有与原发灶明显不同的表达谱，其中TGFBR2明显高表达于CTCs，推测可能与鼻咽癌CTCs的自我更新及表型更迭以获得更高侵袭转移能力有关。本研究拟在鼻咽癌细胞株上过表达或沉默TGFBR2蛋白的表达后，检验其对细胞迁徙及侵袭能力的改变，并运用高通量蛋白芯片筛选出受TGFBR2调控的相关功能蛋白分子。利用裸鼠肺血行转移瘤模型检验TGFBR2表达对肿瘤血行转移及定植能力的影响，进一步在体内阐明该蛋白的肿瘤转移相关功能。通过随访观察TGFBR2在CTCs的表达水平对转移风险及预后的临床价值。本研究将为阐明TGFBR2如何参与鼻咽癌血行远处转移提供科学依据，有望从中探索到抗鼻咽癌血行转移的治疗靶点。

鼻咽癌具有高度的侵袭转移倾向，其中血行播散是鼻咽癌远处转移的主要方式。通过全外显子测序我们发现，相较于原发灶外显子突变更为频发于鼻咽癌循环肿瘤细胞(CTCs)，而RNA表达芯片显示CTCs具有与原发灶明显不同的表达谱，其中TGFBR2明显高表达于CTCs，推测可能与鼻咽癌CTCs的自我更新及表型更迭以获得更高侵袭转移能力有关。本研究在鼻咽癌细胞株上过表达或沉默TGFBR2蛋白的表达后，检验其对细胞迁徙及侵袭能力的改变，并运用高通量测序筛选出受TGFBR2调控的相关功能蛋白分子。利用裸鼠肺血行转移瘤模型检验TGFBR2表达对肿瘤血行转移及定植能力的影响，进一步在体内阐明该蛋白的肿瘤转移相关功能。实验结果显示，TGFBR2表达下调可促进鼻咽癌细胞的迁移、侵袭、增殖、血管形成及肿瘤球形成等表型，并通过高通量测序，筛选出3930个与TGFBR2表达相关的差异表达基因，其中上调基因1783个，下调基因2147个。根据上述结果，TGFBR2的表达下调可能促进鼻咽癌的转移及增殖，并促进肿瘤血管生成及干细胞特性的形成。