Peptide regulatory factors and malignancy

Growth factors and gut function

Growth factors play a key role in maintaining gut integrity and in stimulating repair. By understanding their physiological function we can use this information to apply to the treatment of conditions in which mucosal homeostasis has broken down.

Tales from the human crypt--intestinal stem cell repertoire and the origins of human cancer

A generally accepted model for the origin of human cancer is that tumours arising from the gut-lining epithelium--the adenomas and carcinomas--are of clonal origin, i.e., they are derived from a single 'abnormal' cell. Recent work has shed considerable light on these matters and suggests that this model may be erroneous and that at least some adenomas are of multiclonal origin. These findings have basic implications for more generalized models of tumourigenesis and for researchers examining the potential clinical value of gene therapy.

Effect of suture material on tumour cell adherence at sites of colonic injury

In an experimental animal model, radiolabelled viable intraperitoneal adenocarcinoma cells adhered in similar numbers to normal rat colon and that injured by a 1-cm colotomy, with median cell counts of 7002 and 8602 respectively (P not significant). Repair of the colotomy with interrupted silk resulted in a significant increase in the median number of cells adhering to the injury site (21,888; P = 0.0001 versus normal colon). Repair with Prolene had no effect on tumour cell adherence (a median of 7449 cells adhered; P not significant versus normal colon). Tumour cell adherence at sites of colonic injury is dependent on the suture material used and not on the injury itself in this model. This may be important when choosing suture type for anastomosis in patients undergoing surgery for colorectal cancer.

The relationship of psoriasis to malignancy: a clinical report

A large variety of cutaneous reactions to malignancy have been described but to our knowledge none include psoriasis. Two cases of psoriasiform reactions in association with malignancy were first documented by Braverman, and Bazex's syndrome is now well documented in the literature. Both conditions, although clinically psoriasiform, are said to demonstrate an eczematous histology. A number of patients with psoriasis and malignancy have presented to us in the Dermatology Department. The appearance or behaviour of their psoriasis appeared to be linked to their malignancy. We have collected them together to report on this phenomenon which appears infrequently in the literature.

Mechanisms of somatostatin action in RINm5F cells in culture: Preliminary evidence for possible altered G protein function

Octreotide (SMS), a somatostatin analogue, is an established antigrowth peptide, but it does not effectively inhibit the growth of insulinoma cells. In order to study the mechanisms that underlie this apparent lack of an antiproliferative effect on insulinoma tumor cells we established the rat insulinoma cell line, RINm5F, in culture. Cells in culture were tested by incubation in media with and without SMS. To study tritiated [3H]-thymidine incorporation into extracted DNA (TTID), 2 muCi/well of 3H was added for 24 hr, and cells were harvested and assayed for TTID (cpm/microgram DNA). Insulin (IRI) and intracellular cAMP (cAMPi) were measured by RIA. To study the effects of SMS on insulin secretion, conditioned media were sampled after 24 hr. To study the effects of cAMPi, conditioned medium was used to extract cAMPi following incubation with SMS for 15 min. Increasing concentrations of SMS had no significant effect on TTID in the presence of 1% FBS. Trypan blue exclusion tests showed > 90% viable cells throughout all stages of these experiments. There were no significant differences in cell numbers and protein content in the presence of SMS. There was a significant decrease in the secretion of insulin and intracellular cAMP levels in response to 50 nM SMS. However, SMS significantly inhibited TTID in RINm5F cells following a 4-hr pretreatment with pertussis toxin (PT) (23553 +/- 1747 vs 20635 [cpm/microgram DNA] +/- 1983 [SEM], P < 0.01). We conclude that the inhibition of insulin secretion by SMS is associated with an attenuation of cAMP formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Is hypergastrinaemia dangerous for man?

Several gastric mucosal diseases and the response to powerful gastric secretory inhibitors are accompanied by hypergastrinaemia. When the gastric mucosa is functioning normally, hypergastrinaemia may be dangerous as a consequence of gastric hypersecretion. When the gastric mucosa is functionally abnormal, hypergastrinaemia produces no apparent adverse effects on health. However, the diseases giving rise to hypergastrinaemia are very dangerous because they are often the precursors of gastric cancer. In view of the probable mechanisms of gastric carcinogenesis, it is argued that therapeutic achlorhydria is also potentially dangerous irrespective of the absence or presence of 'hypergastrinaemia'.

Hypocholesterolaemia and increased elimination of low-density lipoproteins in metastatic cancer of the prostate

To study the influence of tumour mass on lipid metabolism, the lipoprotein pattern in untreated patients with newly diagnosed cancer of the prostate was examined. Total cholesterol levels were reduced in patients with evidence of metastasis (n = 30) compared with those without metastasis (n = 73). Since the major fraction of serum cholesterol is contained in low-density lipoproteins (LDL), turnover of LDL was studied in detail in 8 patients compared with 12 age-matched healthy men. LDL were cleared faster in the 3 patients with metastatic disease than in the patients without metastasis and in controls, indicating faster catabolism of LDL. Thus in prostatic cancer an increased tumour burden is associated with increased elimination of LDL, which contributes to reduced serum cholesterol levels.