sq-23377 and Mouth-Neoplasms

We have demonstrated using the reduction of cytochrome c, that the keratinocyte cell line H357 generates superoxide at significant rates (8.36 nmol/h/10[6] cells). The rate of superoxide release decreased as the cells reached confluence. Superoxide production was increased more than twofold following preincubation with IL-1beta, or by the addition of the Ca2+ ionophore, Ionomycin. Other stimuli known to activate the NADPH oxidase of phagocytes were ineffective, but the regulatory cytokine IFNgamma lowered the rate of release. Inhibitors of lipoxygenase function decreased the rate of superoxide production, whereas inhibitors of cyclo-oxygenase, xanthine oxidase, or NADPH oxidase failed to inhibit. The addition of NADH or NADPH to whole cells increased the rate threefold.

Topics: Cytochrome c Group; Humans; Indoles; Interferon-gamma; Interleukin-1; Ionomycin; Ionophores; Keratinocytes; Lipoxygenase Inhibitors; Microscopy, Fluorescence; Mouth Neoplasms; NAD; NADP; NADPH Oxidases; Superoxides; Tumor Cells, Cultured

Humoral hypercalcemia of malignancy is a paraneoplastic syndrome associated with a variety of solid neoplasms including squamous cell carcinomas of various sites. Parathyroid hormone-related protein (PTHrP) is a newly recognized hormone that has been implicated as one of the major causative factors in the pathogenesis of this syndrome. A canine oral squamous carcinoma cell line (SCC 2/88) was used to investigate the regulation of production of PTHrP in response to agents that alter keratinocyte differentiation/proliferation in vitro.. SCC 2/88 cells grown in serum-free media were exposed to various factors and PTHrP production was measured by radioimmunoassay. This cell line spontaneously produced substantial amounts of PTHrP (up to 7,000 pg/ml) without the need for a fibroblast-feeder layer. Production of PTHrP decreased at cellular confluence, and with increasing passage number.. Epidermal growth factor, cholera toxin, calcium, 1,25-dihydroxyvitamin D, ionomycin, trans-retinoic acid, transforming growth factor-beta 1 and hydrocortisone stimulated production of PTHrP by SCC 2/88 cells to various degrees. Transforming growth factor-beta 1 was the most potent stimulator of PTHrP production, with a maximal stimulation of 25-fold over control. Monensin decreased PTHrP secretion as early as 6 hours post-treatment and by 48 hours, there was no detectable PTHrP in the conditioned cell culture medium. Calcium, cholera toxin, ionomycin, and transforming growth factor-beta 1 decreased keratinocyte proliferation as measured by cell counts at all doses tested.. The results of this study revealed that SCC 2/88 cells spontaneously produced substantial amounts of PTHrP under baseline conditions and that compounds known to affect keratinocyte differentiation/proliferation up-regulated production of PTHrP. These cells will be valuable to investigate the molecular regulation of PTHrP production by squamous cell carcinomas.

Topics: Animals; Calcitriol; Calcium; Carcinoma, Squamous Cell; Cell Differentiation; Cell Division; Cell Line; Cholera Toxin; Dog Diseases; Dogs; Dose-Response Relationship, Drug; Epidermal Growth Factor; Humans; Hydrocortisone; Ionomycin; Keratinocytes; Kinetics; Mouth Neoplasms; Neoplasm Proteins; Parathyroid Hormone-Related Protein; Protein Biosynthesis; Radioimmunoassay; Time Factors; Transforming Growth Factor beta; Tretinoin; Tumor Cells, Cultured