Takeda Atsushi, Kajiya Akane, Iwasawa Atsuo, Nakamura Yoshiko, Hibino Toshihiko
Laboratory of Biochemistry, Faculty of Arts and Sciences, Sagami Women's University, Sagamihara-shi, Kanagawa, Japan.
Biol Chem. 2002 Jul-Aug;383(7-8):1231-6. doi: 10.1515/BC.2002.136.
Squamous cell carcinoma antigens (SCCA) 1 and 2 are highly homologous proteins of the serpin family, although they inhibit different types of proteinases. We investigated the expression of both SCCA mRNAs in tumor tissues, in various cell lines (A431, SAS, Ca9, HeLa, SKGIIIa, HSC-2, HSC-3, HSC-4 and KB) and in HSC cell lines in the presence of tumor necrosis factor-alpha (TNF-alpha). The expression of SCCA2 mRNA could be differentiated from that of SCCA1 in tumor tissues and cell lines by means of reverse transcription-polymerase chain reaction (RT-PCR). The ratio between SCCA1 and SCCA2 mRNA expression showed selective expression of SCCA2 mRNA in SCC tissues from the uterine cervix compared to SCC tissues from the esophagus or skin. In addition, a significant level of SCCA2 mRNA expression was detected in the HSC-4 cell line, but not in Ca9, HeLa, SKG-IIIa, or HSC-3 cells. In contrast, SCCA1 mRNA was detected in all samples tested. These results suggest that the level of expression of SCCA2 mRNA detected by RT-PCR can be used to evaluate the status of SCC tumors. Next, we studied the effect of TNF-alpha on SCCA1 and SCCA2 mRNA expression in HSC cell lines. SCCA1 mRNA expression was constantly increased in the three HSC cells examined with increasing time of exposure to TNF-alpha. In contrast, SCCA2 mRNA expression was specific for HSC-4 cells. The survival rate of HSC-4 cells pretreated with TNF-alpha (6.3 ng/ml) for 48 h was found to be 72%, compared with 42% and 9% for HSC-3 and HSC-2 cells, respectively, after apoptotic stimulation by TNF-alpha (10 ng/ml) and cycloheximide (10 microg/ml) for 18 h. Furthermore, selective expression of SCCA2 mRNA in HSC-4 pretreated with TNF-alpha protected these cells from TNF-alpha-mediated apoptosis. Thus, SCCA2 overexpression in squamous tumor cells contributed to their survival by protecting them against TNF-alpha-induced apoptosis.
鳞状细胞癌抗原（SCCA）1和2是丝氨酸蛋白酶抑制剂家族中高度同源的蛋白质，尽管它们抑制不同类型的蛋白酶。我们研究了SCCA两种mRNA在肿瘤组织、各种细胞系（A431、SAS、Ca9、HeLa、SKGIIIa、HSC - 2、HSC - 3、HSC - 4和KB）以及在存在肿瘤坏死因子 - α（TNF - α）的情况下HSC细胞系中的表达。通过逆转录 - 聚合酶链反应（RT - PCR），可以区分肿瘤组织和细胞系中SCCA2 mRNA与SCCA1 mRNA的表达。与来自食管或皮肤的鳞状细胞癌（SCC）组织相比，SCCA1和SCCA2 mRNA表达的比率显示子宫颈SCC组织中SCCA2 mRNA的选择性表达。此外，在HSC - 4细胞系中检测到显著水平的SCCA2 mRNA表达，但在Ca9、HeLa、SKG - IIIa或HSC - 3细胞中未检测到。相反，在所有测试样品中均检测到SCCA1 mRNA。这些结果表明，通过RT - PCR检测到的SCCA2 mRNA表达水平可用于评估SCC肿瘤的状态。接下来，我们研究了TNF - α对HSC细胞系中SCCA1和SCCA2 mRNA表达的影响。在所检测的三种HSC细胞中，随着暴露于TNF - α时间的增加，SCCA1 mRNA表达持续增加。相比之下，SCCA2 mRNA表达对HSC - 4细胞具有特异性。发现用TNF - α（6.3 ng/ml）预处理48小时的HSC - 4细胞的存活率为72%，而在用TNF - α（10 ng/ml）和环己酰亚胺（10 μg/ml）凋亡刺激18小时后，HSC - 3和HSC - 2细胞的存活率分别为42%和9%。此外，在经TNF - α预处理的HSC - 4中SCCA2 mRNA的选择性表达保护这些细胞免受TNF - α介导的凋亡。因此，鳞状肿瘤细胞中SCCA2的过表达通过保护它们免受TNF - α诱导的凋亡而有助于其存活。
