Tanita J, Tsuchida S, Hozawa J, Sato K
Department of Otorhinolaryngology, Hirosaki University School of Medicine, Japan.
Cancer. 1993 Jul 15;72(2):569-76. doi: 10.1002/1097-0142(19930715)72:2<569::aid-cncr2820720239>3.0.co;2-7.
The expression of the placental form of glutathione S-transferase (GST-pi) in human squamous cell carcinomas of the pharynx and larynx was investigated immunohistochemically before and after radiation therapy.
Before the treatment, 47 of 71 carcinoma specimens (66.2%) demonstrated positive reactions, GST-pi being diffusely stained throughout the tumor lesions. Positive rates for moderately and well differentiated carcinomas were 69.7% and 88.0%, respectively, with both of these values being significantly higher than that for poorly differentiated carcinomas (15.4%, P < 0.01). Thus, GST-pi expression seems to be related to the degree of differentiation. Although several tumors exhibiting GST-pi staining did not respond to radiation therapy, most cases responded positively and no relation was apparent in the 41 cases of squamous cell carcinoma studied between response to radiation therapy and previous GST-pi staining. After irradiation of 1000 to 7000 cGy, however, most carcinoma specimens exhibited negative GST-pi staining, regardless of response to radiation therapy.
The results suggest that although GST-pi expression is not directly involved in determining sensitivity to radiation, GST-pi expression can be influenced by exogenous agents. The loss or decrease of GST-pi after irradiation is in clear contrast to the enhanced expression observed in many cancer cell lines resistant to chemotherapy.
采用免疫组织化学方法，研究了谷胱甘肽S-转移酶胎盘型（GST-pi）在人咽喉部鳞状细胞癌放疗前后的表达情况。
治疗前，71例癌组织标本中有47例（66.2%）呈阳性反应，GST-pi在整个肿瘤病灶中呈弥漫性染色。中分化和高分化癌的阳性率分别为69.7%和88.0%，均显著高于低分化癌（15.4%，P<0.01）。因此，GST-pi表达似乎与分化程度有关。虽然部分显示GST-pi染色的肿瘤对放疗无反应，但大多数病例反应良好，在研究的41例鳞状细胞癌中，放疗反应与之前的GST-pi染色之间无明显关系。然而，照射1000至7000 cGy后，无论放疗反应如何，大多数癌组织标本GST-pi染色均呈阴性。
结果表明，虽然GST-pi表达不直接参与决定对放疗的敏感性，但GST-pi表达可受外源性因素影响。放疗后GST-pi的缺失或减少与许多耐化疗癌细胞系中观察到的表达增强形成鲜明对比。
