Strain differences and inheritance of angiogenic versus angiostatic activity in oestrogen-induced rat pituitary tumours.
In this study we investigated the control of the angiogenic/haemorrhagic phenotype of oestrogen-induced rat pituitary tumours of an F1 hybrid (F1) of Fischer 344 (F344) (tumour susceptible) and Brown Norway (tumour resistant) strains. F1 forms a pituitary tumour upon chronic oestrogen treatment, but microvessel count (MVC) is no greater than untreated. In other words, F1 MVC keeps pace with tissue growth during growth of an oestrogen-induced tumour. On the other hand, F344 showed a significant increase in MVC (P = 0.002) upon chronic oestrogen treatment during growth of a large pituitary tumour. F1 control vasculature showed features intermediate between the parent strains, while oestrogen-treated F1 pituitary has pronounced changes commensurate with vascular remodelling or angiogenic activity, along with regressive changes. In addition, oestrogen-treated F1 does not form the haemorrhagic lakes characteristic of oestrogen-treated F344. We conclude that F1, which has a 50-50 genetic composition of the tumour susceptibility and tumour resistance alleles, shows loss of angiostatic activity in the absence of an effective angiogenic stimulus. As a result it is unable to make the 'switch' to the angiogenic phenotype.
Pandey
Jyotsna
J
Department of Biological Sciences and Center for Biomedical Research, Oakland University, Rochester, Michigan 48309, USA.
Cracchiolo
Danny
D
Hansen
Fay M
FM
Wendell
Douglas L
DL
D000818:Animals; D004967:Estrogens / Q000502:physiology; D005260:Female; D008854:Microscopy, Electron; D009389:Neovascularization, Pathologic / Q000235:genetics* / Q000378:metabolism; D010911:Pituitary Neoplasms / Q000098:blood supply* / Q000235:genetics* / Q000648:ultrastructure; D051381:Rats; D011914:Rats, Inbred BN; D011916:Rats, Inbred F344
D004967:Estrogens