The expression and role of insulin-like growth factor II in malignant hemangiopericytomas.

Hemangiopericytoma is a rare soft tissue tumor originating from contractile pericapillary pericytes. To address the issue of molecular genetic events that participate in genesis and progression of hemangiopericytoma we analyzed insulin-like growth factor (IGF) II and IGF I receptor in 29 tumors collected from a human tumor bank network. Seven of these tumors were associated with severe hypoglycemia; six were retroperitoneal and one was located in the leg. Of 22 tumors tested 12 (54.5%) exhibited IGF II mRNA, while almost 90% (17 of 19) of hemangiopericytomas exhibited IGF I receptor mRNA. Sera from some patients whose tumors expressed IGF II mRNA contained elevated levels of IGF II. Removal of the tumor eliminated most of the IGF II immunoreactivity from the sera. The potential role of IGF II as a growth-promoting factor was examined on three malignant primary hemangiopericytoma cell cultures. Extracellular addition of IGF II significantly enhanced cell proliferation in a dose-dependent manner. Antisense oligodeoxynucleotides that specifically inhibit IGF II mRNA, at a concentration of 40 or 80 micrograms/ml, inhibited the growth of hemangiopericytoma cells significantly, by 40%. Simultaneous administration of antisense deoxyoligonucleotides to both IGF II and IGF I receptor inhibited tumor cell proliferation by even 80%. Our data suggest that tumor cells produce IGF II, and that this in turn stimulates their proliferation by autocrine mechanisms.

Direct cellular effects of some mediators, hormones and growth factor-like agents on denervated (isolated) rat gastric mucosal cells.

The brain-gut axis has an important role in the mechanism of gastric cytoprotection in vivo. The aim of this study was to evaluate the in vitro effect of protective agents without any central and peripheral innervation. A mixed population of rat gastric mucosal cells was isolated by the method of Nagy et al (Gastroenterology (1994) 77, 433-443). Cells were incubated for 60 min with cytoprotective drugs such as prostacyclin, histamine, pentagastrin and PL-10 substances (synthesized parts of BPC). At the end of this incubation cells were treated by 15% ethanol for 5 min. Cell viability was tested by trypan blue exclusion test and succinic dehydrogenase activity. The following results were obtained: 1) prostacyclin, histamine and pentagastrin had no direct cytoprotective effect on isolated cells; and 2) PL-10 substances significantly protected the cells against ethanol-induced cellular damage. This led to the following conclusions: 1) in the phenomenon of gastric cytoprotection only the growth factor-like agents have a direct cellular effect; and 2) the intact peripheral innervation is basically necessary for the development of mediators and hormone-induced gastric cytoprotection.

Some aspects of the effects of PL-10.1.AK-15 on the gastrointestinal tract.

PL-10.1.AK-15 is an active fragment of a naturally occurring protein first isolated from human gastric juice. Among its other protective effects, PL-10.1.AK-15 has demonstrated a protective effect on the gastrointestinal tract. The aim of this study was to investigate the influence of PL-10.1.AK-15 on two functional parameters of gastrointestinal function: gastric acid secretion and gastrointestinal motility. Gastric acid secretion was assessed in male Wistar rats using a modified method of Shay, while gastrointestinal motility was assessed in male NMRI mice by charcoal propulsion. PL-10.1.AK-15 was given in three different doses (3, 10 and 100 micrograms/kg body weight) in accordance with the experimental protocol. The results of these experiments indicate that PL-10.1.AK-15 in the investigated doses had no influence on gastric acid secretion or gastrointestinal motility.

Histopathologic features of T-cell mediated colonic injury induced with 2,4-dinitrofluorobenzene in BALB/c mice.

The aim of the study was to reveal the histopathologic features of intestinal inflammation as demonstrated in BALB/c mice, using the challenge of 2,4-dinitrofluorobenzene (DNFB) with or without previous sensitization. Forty mice were randomized into 5 groups. Two groups of animals were treated with rectal enema of 0.2% or 1.0% of 2,4-dinitrofluorobenzene solution. Third group was pretreated with 2 sensitizing doses of DNFB. Two control groups were treated with PBS or acetone and vehicle enema only (acetone and olive oil). In order to assess the extent of colonic inflammation and damage, a histopathologic score scale was developed. In contrast to scanty superficial ulcerations and mild edema observed in the control group of animals, edema, ulcerations, hemorrhage, necrosis and infiltration of inflammatory cells were observed in experiment groups treated with enema of DNFB. Total score of lesion as well almost all inflammatory parameters of injury observed were highest in previously sensitized animals. The results of this study clearly demonstrated the pattern of colonic inflammation induced with DNFB using the histopathologic scoring scale system.

Evidence for direct cellular protective effect of PL-10 substances (synthesized parts of body protection compound, BPC) and their specificity to gastric mucosal cells.

The direct gastric mucosal cellular effect of four PL-10 substances (a synthesized part of human body protection compound, BPC containing 14 or 15 amino acids) was studied on freshly isolated rat gastric mucosal cells and on a mouse myeloma cell line (Sp2/0-Ag14) in an ethanol-induced cell injury model. The examined substances were not toxic for the cells. Two of them proved to be significantly protective against the direct cellular damaging effect of ethanol (PL 10.1.15AK-3 in 5 microg/ml dose and PL 10.1.AK14-2 dose-dependently, ED50=50 ng/ml) on gastric mucosal cells. This cytoprotective effect was failured on mouse myeloma cells. Based on these results a part of the in vivo protection induced by BPC seems to be a direct cellular protective effect to gastric mucosal cells.