Vanadium ions stimulate DNA synthesis in Swiss mouse 3T3 and 3T6 cells.

Abstract

Vanadyl sulfate and sodium orthovanadate in the concentration range between 5 and 50 IAM are shown to be mitogenic for quiescent cultures of Swiss mouse 3T3 and 3T6 cells. The compounds caused a striking shift in the dose-response for the effect of serum on [3Hjthymidine incorporation and DNA synthesis. In the absence of serum the effect of vanadium was greatly potentiated by insulin. Vanadium ionr produced no more than additive increases in [3H]thymidine. incorporation when combined with epidermal growth factor, cholera toxin, or phorbol 12-myristate 13-acetate. Both vanadium compounds stimulated ouabaininhibitable 86Rb+ uptake, indicating that the vanadium ions increase, rather than inhibit, Na+/K' pump activity in the intact cell. Neither vanadium compound had any effect on cellular cAMP under a variety of different conditions. The mitogenic effect of the vanadium compounds was similar to that of colehicine. Taxol, which stabilizes cytoplasmic microtubules, prevented the stimulation of DNA synthesis by vanadium.Quiescent cultures of mammalian cells can be induced to synthesize DNA and proliferate by certain combinations of growthstimulating compounds (1-3). Several animal cell lines have been continuously passaged for many generations in a serum-free medium supplemented with an optimal combination of growthpromoting hormones (2). In fibroblastic Swiss mouse 3T3 cells; a variety of different agents have been identified as potent comitogens: epidermal growth factor (EGF) (4); insulin-like growth factors (5); vasopressin-(6); the tumor promoter phorbol 12-myristate 13-acetate (PMA) (7, 8); platelet-derived growth factor (PDGF) (9); cholera toxin (10, 11); sarcoma-derived growth factor (12); and antitubulin agents (13)(14)(15)(16).Some of these agents alter distinctly different cellular processes, whereas others appear to have a common mechanism of action. For example, cholera toxin increases cAMP (11), and EGF and PDGF modulate phosphotyrosine formation via a protein kinase (17,18). Studies with colchicine and other antitubulin compounds suggest that the depolymerization of cytoplasmic microtubules enhances the mitogenic response to various growth factors (13)(14)(15)(16). Vasopressin and PMA seem to share a common mechanism (19), perhaps involving an increase in the permeability of the cell to ions (20,21). A greater permeability to Na ions appears to be at least partially responsible for the increase in Na+/K' pump activity (22), which occurs shortly after mitogen addition in a variety of different cell types (23-28).We are using vanadium compounds to help in the identification of specific biochemical events involved in the stimulation of DNA synthesis and proliferation in quiescent cells in vitro. * Vanadium is an essential nutrient for higher animals (30), but no specific physiologic role of vanadium has been identified. In the rat, a dietary deficiency of vanadium produces a general retardation of growth, and only about 100 parts perk billion (2 nM) vanadium is needed for normal growth (30). McKeeh...

A mitogen-responsive promoter region that is synergistically activated through multiple signalling pathways.

“…Treatment of cultured cells with vanadate has been shown to stimulate DNA synthesis (32) and cell proliferation (18) and to transform normal fibroblasts phenotypically (18). In vitro, vanadate has been shown to inhibit tyrosine phosphatases selectively (24,30,34), and in living cells, vanadate leads to enhanced tyrosine phosphorylation of numerous proteins (19,37).…”

Activation of mesangial cells by the phosphatase inhibitor vanadate. Potential implications for diabetic nephropathy.

“…For example, vanadate induces angiogenesis and mitogenesis in some mesenchymal cells (7)(8)(9)(10), reverses differentiation of muscle cells mimicking fibroblast growth factor (11 ), prevents cell death of mouse embryo cells caused by growth factor deprivation ( 12), and stimulates hyaluronan synthesis in human mesothelial cells (13). Vanadate has been shown to activate certain signal transduction mechanisms.…”

Vanadate-resistant mutants of Saccharomyces cerevisiae show alterations in protein phosphorylation and growth control.

“…This hypothesis has been supported by a number of reports that have examined the effects of vanadate on phosphorylated compounds in whole cells and cell extracts. In vitro studies indicate that vanadium compounds are potent inhibitors of the Na+-K+ and Ca2'-dependent plasma membrane ATPases (5,11), RNases (38), adenylate kinases, phosphofructokinase, squalene synthetase, and glyceraldehyde-3-phosphate dehydrogenase (41), and protein, acid, and alkaline phosphatases (24,42). In vivo, vanadate has also been shown to have an insulinlike effect on adipocytes (18), to block erythropoiesis of Friend murine erythroleukemia cells (22), to stimulate DNA synthesis (59), and to increase the levels of tyrosine phosphorylation (7,33,63).…”