Fibroblast growth factor-2 expression during experimental oral carcinogenesis. Its possible role in the induction of pre-malignant fibrosis.

BACKGROUND: The fibroblastic growth factor (FGF)-2 has been shown to induce angiogenesis in several tumor types. To date, the activity of FGF during the development of oral pre-cancerous lesions has not been analyzed. We herein evaluated the role of FGF-2 in the pre-cancerous and cancerous lesions in the hamster cheek pouch oral cancer model. METHODS: Expression of FGF-2 and its receptors FGFR-2 and FGFR-3 was assessed by immunohistochemistry at different stages of the carcinogenesis protocol. Activity of FGF-2 isoforms was analyzed by Western blots. RESULTS: Increase and abnormal localization of FGF-2 expression was evident in cancerized epithelium before it was possible to detect morphologic alterations. The changes in FGF-2 are concomitant with the evolution of subepithelial fibrosis. Immunolabeling of carcinomas was faint or completely negative. Increases of FGF-2 activity are mainly due to the increase in the 18 kDa isoform. Receptors 2 and 3 of FGF are present in epithelium, fibroblasts, and vascular endothelia of control samples and in all stages of malignant transformation. CONCLUSIONS: Our results would suggest a role for FGF-2 in the epithelium-connective interactions and a deregulation of its expression in the early stages of oral cancerization. In pre-cancerous tissue FGF-2 would play a central role in the development of fibrosis and a more collateral role in the induction of angiogenesis. The data would indicate its involvement in the process via the 18 kDa isoform.

A new technique for staining mast cells using ferroin.

We describe here a new method for specific staining of mast cells using ferroin. Different hamster tissues were fixed in 4% formalin and processed for paraffin embedding. Sections were stained with hematoxylin followed by ferroin acidified with 2.5 N sulfuric acid to pH 4.0. Mast cells stained an intense orange color that contrasted markedly with bluish violet nuclei. High contrast was also observed when ferroin colored sections were counterstained with light green instead of hematoxylin. To evaluate the specificity of the stain, hamster cheek pouch sections were stained with toluidine blue, alcian blue-safranin O, and ferroin. Quantitative evaluation of mast cells stained with the three techniques showed no statistical difference. The simplicity and selectivity of this method is sufficient for image analysis of mast cells.

Modulation by somatostatin of rat parotid salivary secretion stimulated by cholinergic, adrenergic and peptidergic agents.

Although it is well known that somatostatin (SRIF) modulates several digestive functions, there are only a few reports about its effect on the salivary glands. Here, the action of SRIF parotid secretion was studied, in vivo and in vitro, in male Wistar rats. In vivo SRIF infusion (35 microg/kg per hr) inhibited the parotid flow rate stimulated by methacholine, substance P and noradrenaline. The isoprenaline-stimulated flow rate was also decreased by SRIF, but only at highest dose of the secretory agent. Total protein and amylase secretion were studied. SRIF inhibited the total protein secretion stimulated by the above-mentioned agents, except that by isoprenaline. SRIF did not inhibit in vivo amylase secretion. In order to avoid flow-rate interference with total protein and amylase measurements, in vitro experiments were performed. SRIF (25 nM) strongly inhibited the total protein release stimulated by methacholine (5.1 microM), noradrenaline (19 microM), and substance P (10 microM). The inhibitory effect was not raised by the absence of calcium in the incubation medium. However, in vitro amylase release was not affected by SRIF. It was concluded that SRIF modulates rat parotid secretion stimulated by cholinergic, adrenergic and peptidergic agents, acting on any step in the calcium pathway.