The role of the Peyer's patch in the carcinogenesis of lymphoid cells

Pristane induced gene activation

Studies were performed to examine the effects of 2,6,10,14-tetramethyl pentadecane (pristane) versus 12-O-tetradecanoylphorbol 13-acetate (TPA) on the activation of the CAT gene under the regulatory control of viral promoter/enhancer elements transfected into NIH-3T3, CV-1 and COS-7 cells. The results of these studies demonstrated that (1) pristane or TPA induced trans-activation of SV2cat, HIVcat, RSVcat and MMTVcat in cells transfected with each respective plasmid construct, (2) only pristane induced activation of pA10cat and pOSP/11 and (3) neither TPA nor pristane trans-activated pSV0cat. Furthermore, treatment with either pristane or TPA elicited changes in the morphology of each of the cell lines. Collectively these results indicate that pristane is a potent inducer of gene expression and exhibits similar characteristics as the tumor promoter, TPA.

Thymic tumors induced by 3-methylcholanthrene treatment of rat Peyer's patches

Studies were performed to characterize thymic tumors which were induced after a single injection of 500 microgram or 3-methylcholanthrene (3-MC) into surgically exposed Peyer's patches (PP) of Copenhagen rats. Detailed gross, histological, and morphological analyses revealed thymic tumors differing in size and weight (1 to greater than 8 g) with distorted architecture and infiltration by lymphocytes and epithelial cells in varying proportions. Approximately 25% of the rats with thymic tumors exhibited abnormal spleens, whereas 66% developed low grade leukemias. A majority of the thymic tumors contained cells which exhibited (1) phenotypic markers characteristic of normal thymocytes, (2) abnormal DNA, and (3) increased percentages in S + G2 phases of the cell cycle. Further studies of tumor cell isolates demonstrated an increased frequency of colony formation on soft agar, as well as the ability to elicit thymic tumors upon transplantation. Collectively these studies describe chemically induced thymic lymphomas.