Promotional effects of CO2 laser on DMBA-induced hamster buccal pouch carcinogenesis as shown by immunohistochemistry of the placental form of glutathione S-transferase.
OBJECTIVE
The purpose of the present study was to investigate the kinetics of the expression of the placental form of glutathione S-transferase (GST-P), a useful marker of premalignant lesions, and cell proliferation after CO2 laser surgery on the carcinogen-initiated epithelium.


METHODS
CO2 laser incisions were made on buccal pouch epithelium of 36 hamsters after initiation by 9,10-dimethyl-1,2-benzanthracene (DMBA) (group 1, G1), and scalpel incisions were similarly made on 33 animals (group 2, G2). Twenty animals not treated further after initiation were used as DMBA-treated controls. Incidence of malignant transformation, expression of GST-P, and cell proliferation were examined.


RESULTS
The incidence of malignant transformation in G1 and G2 increased significantly (G1: P < 0.001; G2: P < 0.05) compared with that in DMBA-treated controls. GST-P expression of hyperplasia in G1 and G2 decreased significantly (P < 0.001) compared with that in DMBA-treated controls. In hyperplasia, cell proliferation of the GST-P-negative area was significantly (P < 0.001) higher than that of the GST-P-positive area.


CONCLUSIONS
The incisions, particularly by the CO2 laser, on the initiated areas made expression of GST-P decrease and cell proliferation increase in the GST-P-negative areas. These incisions may serve to promote malignant transformation.
Iida
K
K
Laboratory of Pathology, Aichi Cancer Center Research Institute, Nagoya, Japan.
Kato
M
M
Yoshida
K
K
Kurita
K
K
Tatematsu
M
M
D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D002273:Carcinogens; D002471:Cell Transformation, Neoplastic; D006224:Cricetinae; D005982:Glutathione Transferase / Q000378:metabolism*; D007150:Immunohistochemistry; D053685:Laser Therapy; D008297:Male; D008647:Mesocricetus; D009061:Mouth Mucosa; D009062:Mouth Neoplasms / Q000139:chemically induced*
D002273:Carcinogens; D015127:9,10-Dimethyl-1,2-benzanthracene; D005982:Glutathione Transferase