Telomere shortening sensitizes cancer cells to selected cytotoxic agents: in vitro and in vivo studies and putative mechanisms.

Background: Telomere/telomerase system has been recently recognized as an attractive target for anticancer therapy. Telomerase inhibition results in tumor regression and increased sensitivity to various cytotoxic drugs. However, it has not been fully established yet whether the mediator of these effects is telomerase inhibition per se or telomere shortening resulting from inhibition of telomerase activity.

The rapamycin-derivative RAD001 (everolimus) inhibits cell viability and interacts with the Akt-mTOR-p70S6K pathway in human medullary thyroid carcinoma cells.

Over-expression of the proto-oncogene Akt/PKB has been demonstrated in some neuroendocrine tumor models. Akt may activate downstream proteins such as mTOR and p70S6K, inducing tumor proliferation. The rapamycin-derivative RAD001, everolimus, interacts with this pathway by antagonizing mTOR, but its effects on neuroendocrine tumors are largely unknown.

Ionizing radiation up-regulates telomerase activity in cancer cell lines by post-translational mechanism via ras/phosphatidylinositol 3-kinase/Akt pathway.

Purpose: Telomerase is considered currently as a hallmark of cancer, and its inhibition is expected to become an important anticancer modality. In contrast to abundant data concerning the effect of cytotoxic drugs on telomerase activity (TA), there is scant information on the effect of radiation on telomerase. The mechanism of telomerase regulation by irradiation has never been evaluated in detail.

Lack of plasma norepinephrine cyclicity, increased estradiol during the follicular phase, and of progesterone and gonadotrophins at ovulation in women with premenstrual syndrome.

In healthy women, plasma norepinephrine (NE) has a cycle with the highest levels occurring at ovulation and early luteal phase. We examined plasma NE cyclicity in premenstrual syndrome (PMS) patients as compared to controls, its relation to estradiol (E(2)), progesterone (P), luteinizing hormone and follicle-stimulating hormone, and the correlation of these parameters with the PMS symptoms. Lack of NE cyclicity was observed in PMS patients.

The effect of estrogen replacement therapy on plasma serotonin and catecholamines of postmenopausal women.

We examined the effect of estrogen replacement therapy (ERT) on plasma serotonin (5HT) and norepinephrine (NE) and their correlation with serum estradiol, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in 12 postmenopausal women. Plasma 5HT and NE, estrogen, progesterone, LH and FSH were examined every 4 days for 2 consecutive months (before and during ERT). Serotonin values were low (32.

Protoporphyrin biosynthesis in melanoma B16 cells stimulated by 5-aminolevulinic acid and chemical inducers: characterization of photodynamic inactivation.

The stimulation of protoporphyrin (PP) biosynthesis in B16 melanoma cells in order to facilitate photodynamic cell killing was studied. Biosynthesis and accumulation of PP in the melanoma cells was increased from 8 to 15 pmol/mg protein by the use of dimethyl-sulfoxide (DMSO), a differentiation-inducer. Treatment of the cells with the porphyrogenic agent allylisopropyl-acetamide (AIA) stimulated an additional PP increase.