蛋白激酶Cδ和组织转谷氨酰胺酶是胰腺癌细胞自噬的新型抑制剂。
PKC delta and tissue transglutaminase are novel inhibitors of autophagy in pancreatic cancer cells.
作者信息
Ozpolat Bulent, Akar Ugur, Mehta Kapil, Lopez-Berestein Gabriel
机构信息
Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
出版信息
Autophagy. 2007 Sep-Oct;3(5):480-3. doi: 10.4161/auto.4349. Epub 2007 Apr 27.
Apoptosis (type I) and autophagy (type II) are both highly regulated forms of programmed cell death and play crucial roles in physiological processes such as the development, homeostasis and selective, moderate to massive elimination of cells, if needed. Accumulating evidence suggests that cancer cells, including pancreatic cancer cells, in general tend to have reduced autophagy relative to their normal counterparts and premalignant lesions, supporting the contention that defective autophagy provides resistance to metabolic stress such as hypoxia, acidity and chemotherapeutics, promotes tumor cell survival and plays a role in the process of tumorigenesis. However, the mechanisms underlying the reduced capability of undergoing autophagy in pancreatic cancer remain elusive. In a recent study, we demonstrated a novel mechanism for regulation of autophagy in pancreatic ductal carcinoma cells. We found that protein kinase C-delta (PKC delta) constitutively suppresses autophagy through induction of tissue transglutaminase (TG2). Inhibition of PKC delta/TG2 signaling resulted in significant autophagic cell death that was mediated by Beclin 1. Elevated expression of TG2 in pancreatic cancer cells has been implicated in the development of drug resistance, metastatic phenotype and poor patient prognosis. In conclusion, our data suggest a novel role of PKC delta/TG2 in regulation of autophagy, and that TG2 may serve as an excellent therapeutic target in pancreatic cancer cells.
凋亡(I型)和自噬(II型)都是程序性细胞死亡的高度调控形式,在诸如发育、体内平衡以及在需要时对细胞进行选择性、适度到大量清除等生理过程中发挥着关键作用。越来越多的证据表明,包括胰腺癌细胞在内的癌细胞相对于其正常对应物和癌前病变,通常自噬能力降低,这支持了自噬缺陷为缺氧、酸性环境和化疗等代谢应激提供抗性、促进肿瘤细胞存活并在肿瘤发生过程中起作用的观点。然而,胰腺癌中自噬能力降低的潜在机制仍然不清楚。在最近的一项研究中,我们证明了胰腺导管癌细胞中自噬调节的一种新机制。我们发现蛋白激酶C-δ(PKCδ)通过诱导组织转谷氨酰胺酶(TG2)持续抑制自噬。抑制PKCδ/TG2信号通路导致由Beclin 1介导的显著自噬性细胞死亡。胰腺癌细胞中TG2表达升高与耐药性的发展、转移表型和患者预后不良有关。总之,我们的数据表明PKCδ/TG2在自噬调节中具有新作用,并且TG2可能是胰腺癌细胞的一个极佳治疗靶点。