Pathogenesis of human urinary bladder cancer

Hedgehog signaling restrains bladder cancer progression by eliciting stromal production of urothelial differentiation factors

Hedgehog (Hh) pathway inhibitors are clinically effective in treatment of basal cell carcinoma and medulloblastoma, but fail therapeutically or accelerate progression in treatment of endodermally derived colon and pancreatic cancers. In bladder, another organ of endodermal origin, we find that despite its initial presence in the cancer cell of origin Sonic hedgehog (Shh) expression is invariably lost during progression to invasive urothelial carcinoma. Genetic blockade of stromal response to Shh furthermore dramatically accelerates progression and decreases survival time. This cancer-restraining effect of Hh pathway activity is associated with stromal expression of BMP signals, which stimulate urothelial differentiation. Progression is dramatically reduced by pharmacological activation of BMP pathway activity with low-dose FK506, suggesting an approach to management of human bladder cancer.

Cellular origin of bladder neoplasia and tissue dynamics of its progression to invasive carcinoma

Understanding how malignancies arise within normal tissues requires identification of the cancer cell of origin and knowledge of the cellular and tissue dynamics of tumor progression. Here we examine bladder cancer in a chemical carcinogenesis model that mimics muscle-invasive human bladder cancer. With no prior bias regarding genetic pathways or cell types, we prospectively mark or ablate cells to show that muscle-invasive bladder carcinomas arise exclusively from Sonic hedgehog (Shh)-expressing stem cells in basal urothelium. These carcinomas arise clonally from a single cell whose progeny aggressively colonize a major portion of the urothelium to generate a lesion with histological features identical to human carcinoma-in-situ. Shh-expressing basal cells within this precursor lesion become tumor-initiating cells, although Shh expression is lost in subsequent carcinomas. We thus find that invasive carcinoma is initiated from basal urothelial stem cells but that tumor cell phenotype can diverge significantly from that of the cancer cell-of-origin.

Prospective study of dietary supplements, macronutrients, micronutrients, and risk of bladder cancer in US men

Data derived from laboratory investigations suggest that a number of dietary variables may contribute to bladder carcinogenesis. Although bladder cancer is the fourth leading cause of cancer in men in the United States, dietary studies are few. The authors examined the relations between intakes of macro- and micronutrients and the risk of bladder cancer among men in the prospective Health Professionals Follow-Up Study. Each participant completed a 131-item food frequency questionnaire in 1986 and in 1990, from which nutrient intakes were calculated. During 12 years of follow-up, 320 cases of bladder cancer were diagnosed. No association was observed for total caloric or macronutrient intake and bladder cancer risk. Similarly, we found no relation for dietary intake of potassium, sodium, calcium, magnesium, phosphorus, iron, or water-soluble vitamins and bladder cancer risk. Total vitamin E intake and vitamin E supplements were inversely associated with risk. In addition, a dose-response relation was observed for duration of vitamin E supplement use. A suggestive inverse association was seen with dose of vitamin C supplement use. More studies are needed to determine the role of vitamins E and C supplement intake in bladder carcinogenesis.

Polymorphic oxidation of debrisoquine in bladder cancer

The oxidative polymorphism of debrisoquine has been determined in 125 patients with bladder cancer and in 556 healthy control subjects; 96.6% of patients and 93.9% of controls with a metabolic ratio of debrisoquine less than 12.6 were classified as extensive metabolizers of debrisoquine (P = NS). The distribution of frequencies of metabolic ratio values tended to have lower values in the patients (P less than 0.05), reflecting a higher oxidative rate of debrisoquine in urothelioma patients that cannot be explained solely in terms of enzymatic induction by drugs, tobacco or alcohol. Patients with a high occupational risk for urothelioma had lower metabolic ratio values (P = 0.03). Our results suggest that oxidative polymorphism of debrisoquine might be related to the pathogenesis of bladder cancer.

Growth kinetics and differentiation in vitro of normal human uroepithelial cells on collagen gel substrates in defined medium

Conditions have been described for the selective growth, serial cultivation, and postconfluent morphological differentiation in vitro of normal adult human uroepithelial cells (HUC) on collagen gel substrates in a serum-free medium without the deliberate addition of undefined components and without a requirement for a polypeptide growth factor. The culture medium used (F12) was the standard Ham's F12 medium (0.3 mM calcium) supplemented with 1 microgram/ml hydrocortisone, 5 micrograms/ml transferrin, 10 micrograms/ml insulin, 0.1 mM nonessential amino acids, 2.0 mM L-glutamine, 2.7 mg/ml D-glucose, 10(-4) M ethanolamine or 10(-4) M phosphoethanolamine, and 5 X 10(-8) M selenium. HUC grown in F12 on Type I collagen gel substrates had a generation time of 33 hours and could be serially passed 3-5 times during log phase of growth (20-25 population doublings) before spontaneously senescing. Transmission electron microscopy showed that cultures of HUC grown entirely in serum-free F12 on collagen gel substrates morphologically differentiate postconfluence to resemble in some respects the stratified uroepithelium in vivo, although neither a basal lamina nor an asymmetric unit membrane develop. The addition of epidermal growth factor (EGF) to the F12 did not improve either the growth rate or the lifespan in vitro of HUC. In contrast, the addition of fetal bovine serum (FBS) to F12 was mitogenic to HUC in a dose-dependent manner in the concentration range 0.01-1.00% (4-400 micrograms/ml protein), but higher concentrations of FBS did not improve growth further. The generation time of HUC in 1% FBS-F12 decreased to 21 hours, and the potential population doublings in vitro increased to 31-36. Small amounts (140 micrograms/ml) of bovine pituitary extract (BPE) were similarly mitogenic to HUC in F12. Altering the calcium concentration in the standard Ham's F12 medium (0.3 mM), however, did not improve the growth of HUC in serum-containing or serum-free medium. Higher calcium concentrations (0.30-0.90 mM) were neither mitogenic nor inhibitory to HUC growth, but resulted in decreasing viability of HUC in growing cultures, suggesting an accelerating rate of cellular differentiation. In contrast HUC in low calcium, serum-free F12 (0.1 mM) failed to stratify and morphologically differentiate even in postconfluent cultures. This failure of HUC to differentiate in low calcium F12 medium did not confer a long-term growth advantage.(ABSTRACT TRUNCATED AT 400 WORDS)