Enhanced sensitivity to androgen withdrawal due to overexpression of interleukin-6 in androgen-dependent human prostate cancer LNCaP cells.

BACKGROUND: The objective of this study was to investigate the effects of interleukin-6 (IL-6) overexpression in androgen-dependent prostate cancer LNCaP cells on their phenotype under an androgen-deprived condition. METHODS: We established IL-6-overexpressing LNCaP (LNCaP/IL-6) by introducing the expression vector containing IL-6 cDNA. Changes in the phenotype in LNCaP/IL-6 were compared with that in LNCaP transfected with control vector alone (LNCaP/Co). RESULTS: In vitro, the growth of LNCaP/IL-6 was significantly inferior to that of LNCaP/Co under an androgen-deprived condition. Similarly, LNCaP/IL-6 tumour in nude mice rapidly regressed after castration; however, LNCaP/Co tumour growth was transiently inhibited after castration and then continuously accelerated. After androgen withdrawal, expression levels of phosphorylated p44/42 mitogen-activated protein kinase (MAPK) and Akt in LNCaP/IL-6 were markedly upregulated compared with those in LNCaP/Co; however, additional treatment with specific inhibitor of the MAPK or Akt signalling pathway significantly inhibited the growth of LNCaP/IL-6 compared with that of LNCaP/Co. Furthermore, gene microarray analyses showed that androgen deprivation resulted in differential expression of genes involved in growth, apoptotsis and tumorigenesis between LNCaP/Co and LNCaP/IL-6. CONCLUSION: Excessive secretion of IL-6 by LNCaP cells in an autocrine manner may have a suppressive function in their growth and acquisition of androgen-independent phenotype under an androgen-deprived condition.

Protein kinase C delta specifically associates with phosphatidylinositol 3-kinase following cytokine stimulation.

Phosphatidylinositol (PI) 3-kinase is activated as a result of cytokine-induced association of the enzyme with specific tyrosine-phosphorylated proteins. PI 3-kinase lipid products, PI 3, 4-P2 and PI 3,4,5-P3, have been shown, in vitro, to directly activate novel and atypical protein kinase C (PKC) isozymes. However, the mechanism by which PI 3-kinase may be involved in regulation of PKC isoforms in vivo is presently unknown. We investigated a possible relationship by looking for associations between these enzymes. We found that in a human erythroleukemia cell line, as well as in rabbit platelets, PI 3-kinase and PKCdelta associate in a specific manner that is modulated by cell activation. Granulocyte-macrophage colony-stimulating factor treatment of cells caused increased association of PKCdelta and PI 3-kinase as did treatment of platelets with platelet-activating factor. Results using two PI 3-kinase inhibitors, wortmannin and LY-294002, showed that the former inhibited this association, while the latter did not, suggesting that PI 3-kinase lipid products may not be a prerequisite for the PI 3-kinase/PKCdelta association. Our results also suggest that tyrosine phosphorylation of PKCdelta is not involved in its association with PI 3-kinase.

Effect of a 21-aminosteroid, U74006F, on lipid peroxidation and glomerulotubular function following experimental renal ischemia.

In order to investigate the capacity of the 21-amino-steroid, U74006F, to mitigate ischemic/reperfusion injury (IRI), we studied lipid peroxidation and glomerulotubular function in a rat model of IRI. U74006F, superoxide dismutase (SOD), and their respective vehicles were administered preischemia and prereperfusion to Brown Norway rats subjected to 45 or 60 min of bilateral normothermic ischemia. Lipid peroxidation was assessed by assay of thiobarbituric acid reactive products (TBA-RP) in a forced peroxidation reaction with t-butylhydroperoxide while renal function was assessed by timed determinations of serum creatinine, creatinine clearance, urine volume, and fractional excretion of sodium (FeNa+). Twenty-four hours following a 60-min ischemic insult and uninephrectomy, the glomerular filtration rate (GFR) was markedly reduced in the IRI + vehicle group compared to controls as reflected by a significant elevation in mean serum creatinine (0.138 +/- 0.018 vs 0.045 +/- 0.002 mumole/liter, P < 0.05) and a significant reduction in mean creatinine clearance (0.200 +/- 0.076 vs 1.130 +/- 0.153 ml/min, P < 0.05). Neither U74006F nor SOD afforded protection against this marked fall in GFR. In contrast, U74006F significantly attenuated both the diuresis (UVol) and the increase in fractional excretion of filtered sodium (FeNa+) seen post-IRI. At 24 hr post-IRI, mean UVol was 22.50 +/- 4.57 ml/day and FeNa+ 1.35 +/- 0.16% in the IRI+vehicle group compared to 11.48 +/- 2.00 ml/day and 0.82 +/- 0.22%, respectively, in the IRI+U74006F group (P < 0.05). While SOD also proved partially protective of tubular function, the effect was not as pronounced as that observed with U74006F.(ABSTRACT TRUNCATED AT 250 WORDS)

Patch autografts in the treatment of urethral stricture.

Single-stage skin patch urethroplasty has become accepted therapy for urethral stricture. Review of the literature and the authors' experience indicated good short-term clinical results (80%), but the fate of the implanted tissue has not been well documented. Twenty-three skin and vein patch autograft repairs of defects created in the rabbit urethra were examined histologically after 4 weeks in situ. Two of 12 skin grafts remained intact while 9 of 11 vein patches were successful. The vein patch autograft appears to provide better support because of the survival of the elastic and smooth muscle tissues. Unlike skin grafts, which retain their squamous epithelium, the venous endothelium is entirely replaced by urothelium, thus decreasing potential neoplastic degeneration, and the incidence of fistula formation, fibrosis and chronic inflammation. Further investigation is required before introducing the vein patch urethroplasty into clinical practice.

The development of microsurgical techniques in experimental and clinical repair of urethrocutaneous fistulas.

We reviewed 60 urethral fistulas in 50 patients seen between 1974 and 1979. After the results of this study were assessed technical aspects of the repair were incriminated to account for the 40 per cent failure rate for first-time closure of urethral fistulas in our area. To study this problem an animal model was created in the laboratory. A comparison was made between classically repaired fistulas and those repaired with microsurgical equipment and techniques. In the group repaired by a classical macrosurgical technique only 20 per cent of the repairs were successful, while 90 per cent of the repairs under the microscope succeeded. Techniques and material, as well as histology involved, are presented in detail. Some of the causes of fistula repair breakdown clarified in this study include tissue trauma "para fistula" fistulas due to needle trauma and nonrecognition of multiple small additional fistulas. Details of 25 fistulas in 19 patients in whom closures were done with microsurgical techniques are presented. Success rate for primary closure was 88 per cent.