Transforming growth factor beta-1 and beta-2 and type II receptor functional regulation of ALVA-101 human prostate cancer cells.

Transforming growth factor beta-1 (TGFbeta-1) causes apoptosis of many epithelial cells, including the prostate, but other secondary effects of TGFbeta-1 may be important in carcinogenesis. In a human prostate cancer cell line (ALVA-101), we determined the effects of TGFbeta-1 and TGFbeta type I and II receptor antibody on cell proliferation and TGFbeta-1 receptor binding. TGFbeta-1 and -2 and TGFbeta type II receptor mRNA expression levels were determined by polymerase chain reaction (PCR) and Northern blot analysis. A dose-responsive suppression (0.03 to 10 ng/mL) was observed for cells treated with TGFbeta-1 from 3 to 7 days (P < .01). Untreated cells had 1.1 x 10(3) (n = 3) TGFbeta receptors per cell, with a Kd of 0.20 nmol/L (n = 3) as determined by Scatchard analysis; treatment for 3 days with TGFbeta-1 (1 ng/mL) reduced the receptor number (0.9 x 10(3)) and the Kd (0.12 nmol/L). Antibodies to TGFbeta type I and II receptor stimulated proliferation with or without added TGFbeta-1 (50% +/- 5% above control, P < .01, n = 6). TGFbeta-1 and -2 and TGFbeta type II receptor mRNA expression was observed in untreated cells. In cells treated with TGFbeta-1, TGFbeta-1 mRNA was not affected by treatment, but expression levels of the TGFbeta type II receptor and TGFbeta-2 mRNA were moderately suppressed after 72 hours of treatment. Control cells actively produced TGFbeta-1 as measured by radioimmunoassay. The active and inactive forms of TGFbeta-1 were approximately equal, but TGFbeta-2 was secreted in smaller quantities than TGFbeta-1 and the inactive form of TGFbeta-2 predominated, with very small amounts of the active form. Our results suggest that the human prostate cancer cell line ALVA-101 retains negative control of proliferation in response to TGFbeta-1. Inhibition of endogenous TGFbeta action by antibodies to its receptor enhances the growth of ALVA-101 human prostate cancer cells, suggesting that endogenous TGFbeta exerts an inhibitory control on their growth and cellular function.

Pronuclear positioning and migration during fertilization in Pelvetia.

The position and migration of egg and sperm pronuclei were studied in the brown alga Pelvetia. The egg pronucleus was located near the center of the cell before and after fertilization and, unlike pronuclei in animal eggs, did not migrate. Inhibitor studies indicated that anchoring of the egg pronucleus in the cell center was dependent on microtubules and microfilaments. An extensive array of microtubules, many of which extended into the actin-rich egg cortex, was associated with the egg pronucleus. Migration of the sperm pronucleus was investigated quantitatively in both living and fixed zygotes. Migration occurred linearly at rates from 0.11 to 0.29 microns/min and was oriented directly toward the egg pronucleus in the cell center. Sperm penetration was inhibited by cytochalasin D, which disrupts F-actin function, whereas sperm pronuclear migration was sensitive to the microtubule-depolymerizing drug, nocodazole. Microtubules associated with the migrating sperm pronucleus formed a sperm trail that terminated at the egg cortex. As these were the only microtubules associated with the sperm at early stages of migration, we conclude that they provide the force for migration.