[Biology of cancer cell-stroma interaction in carcinogenesis and cancer progression]

Cancer cells are dependent on physical and chemical supports of stroma no less than non-cancerous cells and tissues are. The role of stroma should, therefore, be important in genesis and progression of cancers growing in vivo. But this aspect underlying carcinogenesis and manifestation of human cancers has long been neglected or attracted less attention in the investigations of oncology. Focusing particular attention on parenchyma-stromal interaction in gastrointestinal mucosa, the authors have found that, quite unexpectedly, in normal gastric as well as intestinal mucosa of all the animal species so for studied, vascularity is always poorly developed in the generative cell zones. Cross-sectional area of vascular bed is markedly reduced in this zone. Application of Hagen-Poiseulle law revealed that the reduced total cross-sectional area, resulting in a rapid drop in hydrostatic pressure, creates here a situation particularly favorable for proliferating cell population. Since the transport of water soluble material together with tissue fluid through the capillary wall is driven by the hydrostatic pressure, the generative cell zones are found to be present at the site where the turnover of the material is the most active. Before the zone of the rapid pressure drop, there appears zone of relatively high intravascular hydrostatic pressure, where secretory function seems to be facilitated. This zone, as is well known, corresponds to glandular portion of the mucosa. After the zone of the rapid pressure drop (in surface of the mucosa), zone of a low intravascular hydrostatic pressure appears, where absorptive function is to be facilitated. Within such zones, in gastric mucosa surface epithelium and in intestinal mucosa absorptive villi cells are located. It is likely that architecture of gastrointestinal epithelium and vascular pattern in the stroma is closely correlated and that the former is determined, at least partly, by the latter. When human gastric mucosa shows intestinal metaplasia, the vascular pattern is always of the type of intestine. Investigating causal relationship of the changes in vascular pattern and epithelial metaplasia, we found that, in human gastric mucosa, vascular architecture began to shift to the intestinal pattern, though not complete, when incipient changes of chronic gastritis became manifest. This is peculiar to human gastric mucosa and thought to be species specific characteristics of mucosal stroma in human stomach.(ABSTRACT TRUNCATED AT 400 WORDS)