乳癌細胞存活機制之探討

Abstract

乳癌是婦女常見的惡性腫瘤，在台灣過去二十年間乳癌的發生率提高了四倍，自2003年起乳癌罹患率超越子宮頸癌成為女性主要癌症死亡排名的第四位，儘管早期檢測技術和治療方法日益進步，但仍有一部分病患在接受手術和化療後產生乳癌的復發，癌幹細胞的假說被認為是解釋乳癌復發及產生抗藥性的原因，雖然有些研究指出可以藉由細胞表面標記以流式細胞儀進行側群細胞的分離藉此分離出癌幹細胞，然而，乳癌幹細胞的特性以及其在乳癌復發及抗藥性產生中所扮演的角色仍然未明。在我們的研究中利用一個無血清的培養環境藉由乳腺球細胞（Mammosphere）的形成去篩選乳癌幹細胞，根據實驗結果顯示可藉由無血清的培養環境從乳癌細胞株(MCF7)以及乳癌病患的檢體中培養出乳腺球細胞，為了要研究乳腺球細胞，我們以MCF7當作研究乳腺球細胞的模式，從MCF7培養出來的乳腺球細胞藉由型態上來區分且在形成過程中會表現integrin a2b1以及其他癌幹細胞的標記，來自乳腺球中的細胞在某些環境中可表現抗藥性(例如：palitaxel)，此外在乳腺球細胞形成過程中會伴隨者Akt磷酸化，顯示出此這條訊息傳遞路徑可能和細胞存活有關，整體而言，我們對於乳癌幹細胞的研究結果可作為臨床上診斷和治療的標記。

Breast cancer is the most commonly seen malignant tumor in women. In Taiwan, the annual breast cancer incidence upraised more than 4 times in the past 20 years. It is the first female cancer over cervical cancer in Taiwanese women since 2003 and the fourth leading cause of cancer death among women. Despite advances in early detection technique and the well-established treatment protocols for patients, cancer recurrence after therapy and long periods of remission is frequent. At that point, resistance to therapy is not only common but expected. The hypothesis for the existence of cancer stem cells was proposed to explain the cancer recurrence and drug resistance in the patients. Although, some of the studies had reported the identification of breast cancer stem cells by the expression of specific cellular surface markers or by the method of side population analysis of flow cytometry. However, the characteristics of breast cancer stem cells and the mechanisms for the cancer stem cells in the cancer recurrence and drug resistance were not clear. In this study, we proposed a serum-free culture system to select breast cancer stem cells via mammary sphere formation. In our studies, the results showed that the mammary spheres were formed in serum free-condition from both the breast cancer cell line (such as MCF-7) and the surgical tissue of patients. In order to characterize the mammary spheres, MCF-7 was applied as a cell model in our study. The MCF-7 derived mammary spheres were distinguished by the morphology, and expressed integrin α2β1 as well as cancer stem cells markers during mammary sphere formation.