Real-time cellular impedance measurements detect Ca(2+) channel-dependent oscillations of morphology in human H295R adrenoma cells.

Endocrine cells, such as H295R have been widely used to study secretion of steroid and other hormones. Exocytosis-dependent hormone release is accompanied by an increase in plasma membrane surface area and a decrease in vesicle content. Recovery of vesicles and decrease in plasma membrane area is achieved by endocytotic processes. These changes in the extent of the surface area lead to morphological changes which can be determined by label-free real-time impedance measurements. Exo- and endocytosis have been described to be triggered by activation of L-type Ca(2+) channels. The present study demonstrates that activation of L-type calcium channels induces prolonged oscillating changes in cellular impedance. The data support the hypothesis that a tight regulation of the intracellular Ca(2+) concentration is a prerequisite for the observed cellular impedance oscillations. Furthermore evidence is presented for a mechanism in which the oscillations depend on a Ca(2+)-triggered calmodulin-dependent cascade involving myosin light chain kinase, nonmuscle myosin II and ultimately actin polymerization, a known determinant for cell shape changes and exocytosis in secretory cells. The described assay provides a method to determine continuously prolonged changes in cellular morphology such as exo/endocytosis cycles. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.

Lycopene reduced gene expression of steroid targets and inflammatory markers in normal rat prostate.

Epidemiological evidence links consumption of lycopene, the red carotenoid of tomato, to reduced prostate cancer risk. We investigated the effect of lycopene in normal prostate tissue to gain insight into the mechanisms, by which lycopene can contribute to primary prostate cancer prevention. We supplemented young rats with 200 ppm lycopene for up to 8 wk, measured the uptake into individual prostate lobes, and analyzed lycopene-induced gene regulations in dorsal and lateral lobes after 8 wk of supplementation. Lycopene accumulated in all four prostate lobes over time, with all-trans lycopene being the predominant isoform. The lateral lobe showed a significantly higher total lycopene content than the other prostate lobes. Transcriptomics analysis revealed that lycopene treatment mildly but significantly reduced gene expression of androgen-metabolizing enzymes and androgen targets. Moreover, local expression of IGF-I was decreased in the lateral lobe. Lycopene also consistently reduced transcript levels of proinflammatory cytokines, immunoglobulins, and immunoglobulin receptors in the lateral lobe. This indicates that lycopene reduced inflammatory signals in the lateral prostate lobe. In summary, we show for the first time that lycopene reduced local prostatic androgen signaling, IGF-I expression, and basal inflammatory signals in normal prostate tissue. All of these mechanisms can contribute to the epidemiologically observed prostate cancer risk reduction by lycopene.