Wang Jiao, Hua Hui, Ran Yuliang, Zhang Hongyin, Liu Weiping, Yang Zhihua, Jiang Yangfu
Division of Signal Transduction and Molecular Targeting Therapy, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, No. 1 Ke Yuan 4 Lu, Chengdu, 610041, China.
Breast Cancer Res. 2008;10(1):R7. doi: 10.1186/bcr1849. Epub 2008 Jan 20.
Aberrant microenvironment and endoplasmic reticulum (ER) stress are associated with solid-tumor progression. Stress proteins, like heat shock proteins and glucose-regulated proteins, are frequently overexpressed in human tumors. It has been reported that derlin-1 is involved in ER stress response. In vitro studies have demonstrated that derlin-1 participates in the retrotranslocation of misfolded proteins from ER into the cytosol. Because the roles of derlin-1 in human cancer have not yet been characterized, we investigated the expression of derlin-1 in human breast carcinoma and whether it protected cancer cells against ER stress-induced apoptosis.
Surgical specimens of human breast cancer and/or paired normal tissues from the same patients were collected for immunohistochemical and/or Western blot analysis with anti-human derlin-1 antibody. The expression of derlin-1 in human breast cancer cell lines was detected by reverse transcription-polymerase chain reaction or Western blot. A synthetic small interfering RNA against derlin-1 was introduced into breast cancer cells to inhibit derlin-1 expression. The effects of derlin-1 knockdown on ER stress-induced apoptosis were determined by flow cytometry analysis.
These analyses demonstrated that 66.7% of the breast carcinoma tissues expressed derlin-1, whereas derlin-1 was rarely expressed in normal mammary glands. The expression of derlin-1 in human breast carcinoma correlated with tumor grade and axillary lymph node metastasis. On examining the expression of derlin-1 in human breast cancer cell lines, we found that derlin-1 expression was enhanced by ER stress-inducing agents. Derlin-1 knockdown sensitized breast cancer cells to ER stress-induced apoptosis.
The observed derlin-1 overexpression in breast cancer, together with its function in relieving ER stress-induced apoptosis, suggests that regulation of the ER stress response pathway may be critical in the development and progression of breast cancer.
异常的微环境和内质网（ER）应激与实体瘤进展相关。应激蛋白，如热休克蛋白和葡萄糖调节蛋白，在人类肿瘤中常过度表达。据报道，Derlin-1参与内质网应激反应。体外研究表明，Derlin-1参与错误折叠蛋白从内质网逆向转运至胞质溶胶。由于Derlin-1在人类癌症中的作用尚未明确，我们研究了Derlin-1在人乳腺癌中的表达以及它是否保护癌细胞免受内质网应激诱导的凋亡。
收集同一患者的人乳腺癌手术标本和/或配对的正常组织，用抗人Derlin-1抗体进行免疫组织化学和/或蛋白质印迹分析。通过逆转录-聚合酶链反应或蛋白质印迹检测人乳腺癌细胞系中Derlin-1的表达。将针对Derlin-1的合成小干扰RNA导入乳腺癌细胞以抑制Derlin-1表达。通过流式细胞术分析确定Derlin-1敲低对内质网应激诱导凋亡的影响。
这些分析表明，66.7%的乳腺癌组织表达Derlin-1，而正常乳腺中很少表达Derlin-1。人乳腺癌中Derlin-1的表达与肿瘤分级和腋窝淋巴结转移相关。在检测人乳腺癌细胞系中Derlin-1的表达时，我们发现内质网应激诱导剂可增强Derlin-1的表达。Derlin-1敲低使乳腺癌细胞对内质网应激诱导的凋亡敏感。
在乳腺癌中观察到的Derlin-1过表达及其在减轻内质网应激诱导凋亡中的作用表明，内质网应激反应途径的调节可能在乳腺癌的发生和进展中起关键作用。
