| 摘要: | 肺癌是導致全球癌症死亡的主要原因。到目前為止，絕大多數癌症患者會接受化療。然而，肺癌的轉移經常引起抗藥性並導致治療後肺癌復發，也有研究顯示，轉移後的癌細胞對於標靶藥物會產生抗藥性。氯米帕明 (clomipramine) 是一種三環抗憂鬱藥，在1960年代被美國食品藥品監督管理局通過用於治療憂鬱症、強迫症、恐慌症。在過去的研究中，氯米帕明被報導對於神經母細胞瘤、骨髓系白血病細胞、淋巴瘤產生細胞凋亡作用。氯米帕明的生物活性代謝物去甲氯米帕明鹽酸鹽 (desmethylclomipramine, DCMI) 被發現對肺腫瘤幹細胞有生長抑制作用。有研究報導顯示，氯米帕明對E3連接酶Itch泛素化的活性具有選擇性抑制，而Itch的缺乏增強了化學治療藥物對腫瘤殺傷的作用。由於轉移性癌細胞顯示出更高的抗藥性，氯米帕明是否在上皮細胞間質轉化肺癌細胞中發揮有效的抗癌活性仍不清楚。因此，本研究假設去甲氯米帕明鹽酸鹽可以有效的毒殺經過上皮細胞間質轉化的肺癌細胞，亦針對其機制進行探討。在本研究中，TGF-β1誘導的人類肺腺癌細胞上皮細胞間質轉化(epithelial mesenchymal transition)，伴隨著fibronectin的表現增加和E-cadherin的表現降低。TGF-β1刺激的人類肺腺癌細胞A549顯示出相對較高cisplatin抗性，而去甲氯米帕明鹽酸鹽的IC90與IC50比鉑順還要低，且針對mesenchymal A549細胞產生良好的毒殺作用。去甲氯米帕明鹽酸鹽通過促使GSK-3β的激活和Mcl-1的降解，Itch表現抑制，cathepsin B/caspase 8 活化tBid的累積，進而導致粒線體失能以引發mesenchymal A549細胞產生凋亡。此外，進一步將TGF-β1刺激的mesenchymal A549癌細胞皮下注射到八週大的裸鼠腫瘤模型中，證實去甲氯米帕明鹽酸能有效地毒殺mesenchymal A549腫瘤並抑制其生長。因此，我們證實去甲氯米帕明鹽酸鹽可以負向調控Akt/GSK-3b/Mcl-1訊號，並且活化cathepsin B/caspase-8依賴型的粒線體凋¬亡機制，進而有效針對TGF-β1誘發的mesenchymal A549癌細胞產生毒殺作用。去甲氯米帕明鹽酸可能發展為針對轉移型肺腺癌的潛在治療藥物。
Lung cancer is the leading cause of cancer deaths worldwide. So far, the vast majority of cancer patients receive chemotherapy. However, metastasis of lung cancer often causes drug resistance and leads to recurrence of lung cancer after treatment. Metastatic cancer cells are also indicated resistant to target drugs. It’s essential to find the effective way to treat metastatic cancer cells. Clomipramine is an FDA-approved tricyclic antidepressant for the treatment of depression, obsessive-compulsive disorder, and panic disorder. In addition, clomipramine has been reported to generate apoptotic effects on neuroblastoma, myeloid leukemia cells, and lymphoma. Desmethylclomipramine (DCMI), a biologically active metabolite of clomipramine, also shows a cytostatic effect on lung cancer stem cells. Since metastatic cancer cells show hyposensitivity to chemotherapeutic drugs, it is unclear whether DCMI exerts the anticancer activity in mesenchymal type lung cancer cells. In the present study, TGF-β1 induced epithelial mesenchymal transition in human lung adenocarcinoma A549 cells, which was accompanied by the increased expression of fibronectin and the decreased expression of E-cadherin. TGF-β1-treated A549 cells showed the hyposensitivity to cisplatin treatment, where cisplatin displayed the higher IC90 and IC50 than DCMI. DCMI treatment caused the inactivation of Akt/GSK-b/Mcl-1 axis, Itch reduction, cathepsin B/caspase 8-dependent tBid accumulation and MTP reduction in TGF-β1-treated A549 cells. Moreover, post-treatment of DCMI effectively promoted TGF-β1-mediated mesenchymal A549 tumor nodule death, and further suppressed tumor growth in nude mice. Taken together, we demonstrated that DCMI mediates antitumor effects on TGF-β1-mediated mesenchymal A549 cells via Akt/GSK-b/Mcl-1 inactivation and cathepsin B/caspase 8-regulated mitochondrial apoptosis, which suggests the potential role of DCMI in mesenchymal cancer cells therapy. |
