探討細胞核中 CTEN 參與調控 NF-κB 及 ERα 訊號反應路徑之功能

Functional relevance of nuclear CTEN in NF-κB and ERα signaling

邱品慈(Ping-Tzu Chiu)

指導教授 ： 廖憶純

國立臺灣大學/生命科學院/生化科技學系/碩士(2016年)

https://doi.org/10.6342/NTU201602533

摘要

C-terminal tensin like (CTEN) 蛋白質，為 tensin 家族中的一員，位於 focal adhesion 上，參與細胞的貼附、增生、遷移等行為。 CTEN 在各個時期的大腸癌腫瘤組織中，皆有過量表現的現象，且於細胞核中也能偵測到高表現量的 CTEN。在人類大腸癌細胞株 SW480 中，CTEN 與 α-actinin4 於細胞核中有交互作用。過去文獻中指出，α-actinin4 在細胞核中作為 transcription factor co-activator 促進 nuclear factor kappa B (NF-κB) 及 estrogen receptor α (ERα) 的轉錄活性，影響其下游基因表現。因此，本研究探討 CTEN 是否參與調控 NF-κB 與 ERα 的訊息傳遞，藉此瞭解細胞核中 CTEN 的功能。本論文發現，在 SW480 中 knockdown CTEN 會導致 NF-κB 的轉錄活性下降，也抑制了下游目標基因 TRAF-1 及 IL-1β 之表現， 推測可能影響 SW480 大腸癌細胞之細胞凋亡及免疫反應。我們也證實 CTEN 不影響 NF-κB 的磷酸化與其在細胞核中的累積量，但與其 subunit, p65 在細胞核中有交互作用。另一方面，本論文證實，在 MCF-7 中過量表現 CTEN 會導致 ERα 的轉錄活性降低，也抑制了下游目標基因 PR、pS2 之表現，進而影響 MCF-7 乳癌細胞之細胞增生能力。

關鍵字

訊號反應路徑 ； 蛋白質交互作用 ； 細胞凋亡 ； 細胞增生

並列摘要

C-terminal tensin like (CTEN) protein, a member of tensin family, locates at focal adhesion and participates in regulation of cell adhesion, proliferation and migration. Elevated CTEN level has been detected in all stage of colon cancers. Furthermore, a high population of CTEN is located in the nucleus and interacts with α-actinin4 in colon cancer cell line, SW480. Previous studies indicated that α-actinin4 might function as a transcription factor co-activator in nuclear factor kappa B (NF-κB) and estrogen receptor α (ERα) signaling pathway in the nucleus. In this study, we investigated that whether nuclear CTEN participates in NF-κB and ERα signaling pathway to elucidate the functional role of CTEN in the nucleus. Our results have shown that knockdown of CTEN down-regulates NF-κB reporter activity and decreases the expression of TRAF-1 and IL-1β, which are NF-κB signaling pathway downstream genes. It suggests that CTEN might affect cell apoptosis and immunity in SW480 colon cancer cells. However, CTEN has no effect on TNFα-induced phosphorylation of p65, IKKβ and IκBα after TNFα stimulation. We demonstrated that CTEN does not affect p65 nuclear translocation but interacts with p65 in the nucleus. Moreover, we found that CTEN repress ERα transcriptional activity. Overexpression of CTEN decreases the expression of ERα downstream genes, PR and pS2 and inhibits cell proliferation activity in MCF-7 breast cancer cells.

並列關鍵字

C-terminal tensin-like protein (CTEN) ； Nuclear-factor-kappa B (NF-κB) ； Estrogen receptor alpha (ERα)

參考文獻

李昌恆 (2014) 探討 CTEN 與 β-catenin 和 α-actinin4之間的交互作用及 CTEN 於細胞核質間穿梭的機制，碩士論文，國立台灣大學生命科學院生化科技學系

Aksenova, V., Turoverova, L., Khotin, M., Magnusson, K. E., Tulchinsky, E., Melino, G., Tentler, D. (2013). Actin-binding protein alpha-actinin 4 (ACTN4) is a transcriptional co-activator of RelA/p65 sub-unit of NF-kB. Oncotarget, 4(2), 362-372.

Al-Ghamdi, S., Cachat, J., Albasri, A., Ahmed, M., Jackson, D., Zaitoun, A., Ilyas, M. (2013). C-terminal tensin-like gene functions as an oncogene and promotes cell motility in pancreatic cancer. Pancreas, 42(1), 135-140.

Albasri, A., Seth, R., Jackson, D., Benhasouna, A., Crook, S., Nateri, A. S., Ilyas, M. (2009). C-terminal Tensin-like (CTEN) is an oncogene which alters cell motility possibly through repression of E-cadherin in colorectal cancer. J Pathol, 218(1), 57-65.

Archbold, H. C., Yang, Y. X., Chen, L., & Cadigan, K. M. (2012). How do they do Wnt they do?: regulation of transcription by the Wnt/beta-catenin pathway. Acta Physiol (Oxf), 204(1), 74-109.