- 學位論文
HPW-RX40在人類乳癌細胞MDA-MB-231誘發失巢凋亡的機制探討
Study on HPW-RX40-Induced Anoikis in Human Breast Cancer MDA-MB-231 Cells
摘要
Anoikis (失巢凋亡)意指當細胞剝離或與貼附表面的交互作用不再穩定時，所產生的細胞凋亡。具有anoikis抗性的癌細胞較有潛力由原位轉移至其他組織，且此現象和FAK與Src的活性相關。HPW-RX40是tyrosine kinase抑制劑3,4-methylenedioxy-nitrostyrene (MNS)的化學合成衍生物。本研究探討HPW-RX40對具有anoikis抗性的人類乳癌細胞─MDA-MB-231─的影響。實驗結果顯示HPW-RX40對於貼附細胞沒有影響，但可選擇性地促使懸浮細胞死亡。經由觀察caspase活性與poly (ADP-ribose) polymerase (PARP)斷裂，確認HPW-RX40造成的懸浮細胞死亡屬於細胞凋亡，亦即HPW-RX40可誘使細胞產生anoikis。進一步探討HPW-RX40造成細胞anoikis 的機轉，發現當細胞剝離時，FAK與Src及其下游分子Paxillin會活化，但HPW-RX40可抑制這些蛋白質的活化。此外，懸浮的MDA-MB-231細胞以HPW-RX40處理後，對Bcl-2家族蛋白也會造成影響。當HPW-RX40與epidermal growth factor receptor (EGFR)抑制劑AG1478合併使用時，對FAK活化的抑制作用及anoikis誘發作用均較單一藥物為強。上述實驗結果顯示HPW-RX40可藉由抑制FAK與Src，使具有轉移能力的癌細胞產生anoikis。因此，HPW-RX40值得進一步探討其成為新的抑制腫瘤轉移藥物的潛力。
關鍵字
失巢凋亡並列摘要
Anoikis is defined as apoptosis which is induced by inappropriate cell-matrix interactions. Cancer cells with anoikis resistance tend to undergo metastasis, and this phenomenon has been reported to be associated with FAK and Src activity. HPW-RX40 is a derivative of 3,4-methylenedioxy-nitrostyrene, which is a non-receptor tyrosine kinase inhibitor. In the present study, we investigated the effect of HPW-RX40 on an anoikis-resistant human breast cancer cell line MDA-MB-231. Our results showed that HPW-RX40 did not affect the monolayer growth of MDA-MB-231 cells, but induced cell death in detached cells. Analysis for caspase activation and poly (ADP-ribose) polymerase (PARP) cleavage confirmed apoptosis (anoikis) in HPW-RX40-treateted suspending cancer cells. To confirm the underlying mechanism, we determined the activation state of Src and FAK. While the breast cancer cells were detached, the activities of both FAK and Src were increased, and HPW-RX40 treatment prevented their activation. Besides, HPW-RX40 also affected the Bcl-2 family proteins in detached cancer cells. While combining with the epidermal growth factor receptor (EGFR) inhibitor AG1478, the anoikis induced by HPW-RX40 in suspended MDA-MB-231 cells was more obvious, and the inhibition of FAK was also enhanced. These results suggest that HPW-RX40 can restore the anoikis sensitivity in the metastatic breast cancer cells by inhibiting FAK and Src, and reveal a potential strategy for prevention of tumor metastasis.