Induction of lymphomas on implantation of human oral squamous cell carcinomas in nude mice.

Cancer cells from five oral cancer patients and pleomorphic adenoma cells from one individual were inoculated as single cell suspension into subcutis of 30 Swiss nude mice and tail vein of additional 30 mice. Further, tumor tissue pieces from three oral cancer patients were xenografted s.c. in 18 nude mice, and 10 mice were kept as controls. In animals implanted with tumor pieces, 7/18 (39%) mice, developed squamous cell carcinoma at the site of inoculation within 8-15 days, while tumors were not observed in mice inoculated with single cell suspension, up to 60/90 days. In 8/68 (12%) mice, white foci were observed in several tissues, with hepatomegaly and splenomegaly noted in 27/68 (39%) mice. Histopathological examination of various tissues revealed presence of large cell lymphoma in several organs in 14/68 (21%) mice. No regional or distant metastasis of the implanted oral tumor cells was detected. Mice injected with cells from pleomorphic adenoma, also demonstrated large cell lymphoma in 2/10 (20%) mice, whereas none of the 10 control animals showed any gross abnormalities or microscopic abnormalities in several organs. 2/16 (12%) lymphomas exhibited positive reaction with mouse B cell antibodies illustrating the murine origin of the lymphomas, and these were immunophenotyed as B cell lymphomas. The lymphomas were also examined with mouse T cell antibodies and none reacted positively with the mouse T cell antibodies. The lymphomas also failed to react with human T cell, B cell and human Leucocyte common antigen (LCA) antibodies, indicating that the induced lymphomas were not of human origin. The tumor specimens from seven of eight oral cancer patients and the pleomorphic adenoma patient induced lymphomas in nude mice. Thus it appears that xenografting oral tumor cells into nude mice may cause induction of the murine lymphomas, and this needs further investigation.

Dual regulatory action of prostatic inhibin (10.7 kDa) on DNA synthesis.

Present studies deal with the role of inhibin in proliferation and growth. The effect of inhibin on incorporation of 3H-thymidine in prostatic DNA in vivo as well as by NRK-49F and Balb/c3T3 cell lines in vitro, was investigated. Also studied the immunocytochemical localization of inhibin in normally proliferating and differentiated tissues of human prostate and endometrium. The in vivo studies revealed a suppression of 3H-thymidine uptake both in ventral (33%) and dorsolateral (26%) lobes of rat prostate. Interestingly, the histology of inhibin treated rat prostate manifested amidst the epithelial lining, an appearance of apoptotic bodies which are considered to be indicative of cell death. Further, the immunocytochemical studies for localization of inhibin showed intense staining in the differentiated human prostate and endometrium as compared to the respective proliferative tissues. Is inhibin kept suppressed in these proliferating tissues, because it is antiproliferative? The present in vitro experiments demonstrated that, at low inhibin concentrations, the incorporation of 3H-thymidine is stimulated while at higher doses it is suppressed. Thus, it is clear that prostatic inhibin seems to have a concentration-dependent dual role in the regulation of DNA synthesis.