KIF12在大腸癌幹細胞中所扮演的角色

大腸直腸癌是全球發生率排名第三的癌症，現今治療方式以手術切除、化學治療及放射治療為主，這些傳統治療方法僅對癌症早期病患有效，對癌症晚期病患治療效果有限。癌症預後不良可能是因為癌症中有一群癌幹細胞存在。癌幹細胞有人稱之為腫瘤初始細胞，癌幹細胞具有自我更新、分裂及分化成癌細胞的能力，同時也具有將化療藥排出細胞外的蛋白質通道，因此癌幹細胞成為癌症預後不良的關鍵之一。我們發現驅動蛋白家族成員12（Kinesin Family Member 12；KIF12）mRNA表現量在大腸癌檢體培養出之類癌幹細胞球中皆高於原腫瘤檢體及其貼盤培養之細胞。KIF12是一種微管相關的運動蛋白，在細胞質分裂時扮演重要角色。為了進一步研究大腸癌幹細胞以及KIF12的關係，我們檢測了五種大腸癌細胞株包括HCT116、HT29、SW480、SW620、與DLD1，其癌細胞和類癌幹細胞的RNA及蛋白質，觀察到在HT29與SW480細胞中，KIF12的表現量在類癌幹細胞中皆比癌細胞高。我們接著以SW480建立削弱KIF12的穩定細胞株（shKIF12），並進行細胞增殖及群落大小檢測。結果顯示shKIF12相較於對照組細胞株（shScramble）在細胞增殖能力上有顯著降低。另外分析shKIF12細胞之細胞週期，發現其相較於對照組細胞株（shScramble）在G0/G1累積上有增加。因自噬作用被研究出可調控癌幹細胞的維持，因此我們亦檢測細胞自噬作用。結果發現shKIF12細胞之自噬作用蛋白LC3B-II蛋白質相較於對照組細胞株（shScramble）有顯著降低。根據以上結果，KIF12可能調節著大腸癌類幹細胞增殖、維持及自噬的能力。

關鍵字

大腸結腸癌；癌症幹細胞；驅動蛋白質超級家族；驅動蛋白質家族成員12

並列摘要

Colorectal cancer (CRC) is the third-leading cancer in the world. The treatments today include surgical excision, radiotherapy and chemotherapy. Patients in the early stages have higher survival rate, but have very poor prognosis in the late stages. Previous studies have reported that the poor prognosis may be due to the existence of cancer stem cells (CSC). These CSCs cause tumor formation, recurrence, metastasis and resistance to chemotherapies. Therefore, CSCs become one of the keys to poor prognosis of patients. We found here that the expression of Kinesin Family Member 12 ( KIF12 ) is higher in tumorspheres compared to the original tumor sample and primary cultured cancer cells. To further study the relationship between CRC stem cells (CRCSC) and KIF12, we examined the RNA and proteins of five colorectal cancer cell lines, including HCT116, HT29, SW480, SW620 and DLD1, by RT-PCR and Western blot analysis respectively. We found that KIF12 was expressed higher in tumorspheres of HT29 and SW480 cells. We next established SW480 stable cell line with knocked-down KIF12 (shKIF12) and performed the cell proliferation and sphere size analysis. The results showed that the proliferation and the size of tumorspheres in shKIF12 cells is significantly decreased compared with control cells (shScramble). Moreover, we analyzed the cell cycle of shKIF12 cells and found the G0/G1 accumulation of these cells compared to control. Since the autophage has been reported to regulate the maintenance of the CSC, we further demonstrated that the expression of autophagy protein LC3B-II is decreased in shKIF12 cells compared to shScramble control. These results showed that KIF12 may be one of the key regulators for the proliferation, maintenance and regulation of autophagy of CRCSCs.

並列關鍵字

Colorectal cancer ； Cancer stem cells ； Kinesin superfamily protein ； Kinesin family member 12

參考文獻

Acunzo, M., et al. (2015). "MicroRNA and cancer--a brief overview." Adv Biol Regul 57: 1-9.

Google Scholar

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