Expression of glutathione S-transferase-π in human squamous cell carcinomas of the pharynx and larynx. Loss after radiation therapy

Autor: Kiyomi Sato, Jiro Tanita, Shigeki Tsuchida, Jiro Hozawa
Rok vydání: 1993
Předmět:
Zdroj: Scopus-Elsevier
ISSN: 1097-0142
0008-543X
DOI: 10.1002/1097-0142(19930715)72:2<569::aid-cncr2820720239>3.0.co;2-7
Popis: BACKGROUND AND METHODS 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. RESULTS 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. CONCLUSIONS 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.
Databáze: OpenAIRE
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