Can cancer cells transform normal host cells into malignant cells?

A human prostate tumour cell line, LNCaP C4-2, when injected into athymic male nude mice, produced tumours containing: (1) only human cancer cells similar to those injected; (2) only murine stromal cells containing abnormal chromosome constitutions; or (3) both human prostate cancer cells similar to those injected and the transformed murine stromal cells with altered chromosome constitutions. Karyotypic analysis of murine metaphases from all the host-derived tumours showed mostly pseudodiploid chromosome constitutions, with multiple copies (amplification) of mouse chromosome 15 and the absence of a typical Y chromosome. Fluorescence in situ hybridization analysis of these murine cells, using a biotin-labelled total human DNA painting probe, further demonstrated the absence of human DNA and the presence of only mouse metaphase and interphase cells in these transformed stromal cells. These results suggest that cancer cells are capable of inducing neoplastic transformation in stromal cells of the host organ by some, as yet unknown, epigenetic mechanism(s).     

Premigratory increase in circulating triiodothyronine/thyroxine ratio in the red-headed bunting (Emberiza bruniceps)

The circulating triiodothyronine/thyroxine ($\text{T}{}_3\text{T}{}_4$) ratio in the red-headed bunting significantly increased prior to migration. Marked extrathyroidal conversion of T₄ to T₃ also occurred. The possibility that migratory disposition in this bird may be related to an increase in serum concentration of T₃ is, therefore, raised.