Transforming growth factor-beta 1 rapidly activates phosphorylase in a calcium-dependent manner in rat hepatocytes

Fatty Acids and Calcium Regulation in Prostate Cancer

Prostate cancer is a widespread malignancy characterized by a comparative ease of primary diagnosis and difficulty in choosing the individualized course of treatment. Management of prostate cancer would benefit from a clearer understanding of the molecular mechanisms behind the transition to the lethal, late-stage forms of the disease, which could potentially yield new biomarkers for differential prognosis and treatment prioritization in addition to possible new therapeutic targets. Epidemiological research has uncovered a significant correlation of prostate cancer incidence and progression with the intake (and often co-intake) of fatty acids and calcium. Additionally, there is evidence of the impact of these nutrients on intracellular signaling, including the mechanisms mediated by the calcium ion as a second messenger. The present review surveys the recent literature on the molecular mechanisms associated with the critical steps in the prostate cancer progression, with special attention paid to the regulation of these processes by fatty acids and calcium homeostasis. Testable hypotheses are put forward that integrate some of the recent results in a more unified picture of these phenomena at the interface of cell signaling and metabolism.

Transforming Growth Factor β1 Function in Airway Remodeling and Hyperresponsiveness. The Missing Link?

The pathogenesis of asthma includes a complex interplay among airway inflammation, hyperresponsiveness, and remodeling. Current evidence suggests that airway structural cells, including bronchial smooth muscle cells, myofibroblasts, fibroblasts, and epithelial cells, mediate all three aspects of asthma pathogenesis. Although studies show a connection between airway remodeling and changes in bronchomotor tone, the relationship between the two remains unclear. Transforming growth factor β1 (TGF-β1), a growth factor elevated in the airway of patients with asthma, plays a role in airway remodeling and in the shortening of various airway structural cells. However, the role of TGF-β1 in mediating airway hyperresponsiveness remains unclear. In this review, we summarize the literature addressing the role of TGF-β1 in airway remodeling and shortening. Through our review, we aim to further elucidate the role of TGF-β1 in asthma pathogenesis and the link between airway remodeling and airway hyperresponsiveness in asthma and to define TGF-β1 as a potential therapeutic target for reducing asthma morbidity and mortality.

Pancreatitis-associated ascitic fluid increases intracellular Ca(2+) concentration on hepatocytes

BACKGROUND

We have reported that pancreatitis-associated ascitic fluid (PAAF) contains a cytotoxic factor(s) inducing apoptosis on renal tubular cells and hepatocytes. It has been suggested that elevation of intracellular Ca(2+) concentration ([Ca(2+)](i)) is associated with the development of cell damage and apoptosis.

METHODS

To clarify the mechanism of hepatocellular injury in acute pancreatitis, the effect of PAAF on hepatocyte [Ca(2+)](i) was investigated. Primary cultures of rat hepatocytes were loaded with Fura-2/acetoxymethyl, and the changes of [Ca(2+)](i) were measured using spectrofluorometer.

RESULTS

The baseline of hepatocyte [Ca(2+)](i) was 172 +/- 17 nM. [Ca(2+)](i) increased from 1 min after the addition of PAAF in a dose-dependent manner. Fractionation of PAAF revealed only one fraction (molecular weight >/= 5 x 10(4)) possessed both [Ca(2+)](i) elevation activity and cytotoxic activity. Neither 8-(N,N-diethyl-amino) octyl-3,4,5-trimethoxybenzoate (TMB-8) nor thapsigargin inhibited the PAAF-evoked [Ca(2+)](i) elevation. Chelation of extracellular Ca(2+) by ethylene glycol bis-(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) prevented the elevation of [Ca(2+)](i), but verapamil did not prevent it. Platelet-activating factor antagonist (TCV-309) blocked the PAAF-elicited [Ca(2+)](i) elevation. Pancreatitis-associated serum also increased hepatocyte [Ca(2+)](i). Moreover, PAAF increased [Ca(2+)](i) on Madin-Darby canine kidney cells in a dose-dependent manner.

CONCLUSIONS

These results suggest that the dramatic elevation of hepatocyte [Ca(2+)](i) due to PAAF may be closely related to the hepatocellular injury in severe acute pancreatitis and that platelet-activating factor may play a pivotal role in increasing hepatocyte [Ca(2+)](i). Elevation of [Ca(2+)](i) in various cells may be involved in the mechanism of multiple organ failure in this disease.

Hepatic Ito cells contain calcium channels: increases with transforming growth factor-beta 1

Ito cells (fat-storing cells) have been implicated in mechanisms of liver fibrosis, and transforming growth factor-beta 1 is a key factor that stimulates collagen production by Ito cells. Moreover, Ito cells are reported to possess contractile proteins and to contract with ligands. We recently reported the presence of L-type voltage-operated Ca2+ channels in Kupffer cells. In this study, we examined whether Ito cells contain Ca2+ channels and also evaluated the effect of transforming growth factor-beta 1 on Ca2+ channels. Cytosolic free calcium concentration was measured in individual cultured Ito cells with the fluorescent Ca2+ indicator dye fura-2. Partial replacement of extracellular Na+ with K+ caused an increase in cytosolic free calcium, presumably as a result of transmembrane Ca2+ influx. Basal cytosolic free calcium levels were around 40 to 50 nmol/L in both control and transforming growth factor-beta 1-treated cells. In transforming growth factor-beta 1-treated cells, cytosolic free calcium increased in response to K+ at values as low as 10 mmol/L, whereas untreated cells did not respond. Half-maximal increases in cytosolic free calcium in transforming growth factor-beta 1-treated cells were observed with 63 +/- 6 mmol/L K+. With 100 mmol/L K+, intracellular free calcium increased around fourfold above basal values in transforming growth factor-beta 1-treated cells but was only increased about twofold in untreated controls. We conclude that this increase in cytosolic free calcium occurs by way of voltage-operated calcium channels; it did not occur in the absence of extracellular calcium and cannot be explained by Na+/Ca2+ exchange mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)