A prolactin-dependent, metastasising rat mammary carcinoma as a model for endocrine-related tumour dormancy.

摘要: In order to study the growth kinetics of breast tumours during long-term hormonal withdrawal, we developed a transplantable, invasive mammary carcinoma EMR-86 that originated in female WAG/Olac rat bearing subcutaneously implanted oestrogen pellet (EP). Outgrowth transplanted occurs only presence an EP, and metastases are formed lungs regional lymph nodes. Subsequent EP removal induces rapid regression. However, do not disappear completely, as small nodules persist. These dormant tumour remnants can be restimulated even after long periods. Because EP-stimulated regressed treatment with bromocriptine non-oestrogenized rats grew out perphenazine, prolactin is major growth-stimulating hormone this model. Cell growing, regressing phase were studied by immunocytochemical detection DNA-incorporated bromodeoxyuridine (BrdUrd) tissue sections. BrdUrd labelling indices decreased from 21.6 +/- 3.0% less than 1% within 7 days removal. After prolonged withdrawal (up 90 days) BrdUrd-labelled cells could always demonstrated (range 0.4-0.8%), without concomitant increase volume. Additional either or ovariectomy significantly reduce residual proliferative activity, continuous experiments. The results indicate vivo dormancy may represent steady state cell division loss, rather accumulation non-cycling G0 state.