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Inorganic phosphate inhibits growth of human osteosarcoma U2OS cells via adenylate cyclase/cAMP pathway

Silvio Naviglio1, Annamaria Spina, Emilio Chiosi

  • 1Department of Biochemistry and Biophysics, Second University of Naples, Medical School, 80138 Naples, Italy. silvio.naviglio@unina2.it

Journal of Cellular Biochemistry
|March 23, 2006
PubMed

Insights

Inorganic phosphate (Pi) regulates cellular functions by decreasing cyclic AMP (cAMP) levels and adenylate cyclase (AC) activity, inhibiting cell growth in U2OS cells. This phosphate signaling pathway impacts cell proliferation.

Area of Science:

  • Cell Biology
  • Molecular Signaling
  • Biochemistry

Background:

  • Phosphate is crucial for cellular functions, but its role as a signaling molecule is increasingly recognized.
  • The adenylate cyclase (AC)/cyclic AMP (cAMP) pathway is a key regulator of intracellular processes.
  • Understanding how extracellular signals modulate the AC/cAMP axis is vital for cell function research.

Purpose of the Study:

  • To investigate the effects of inorganic phosphate (Pi) on the adenylate cyclase (AC)/cyclic AMP (cAMP) signaling pathway.
  • To determine if phosphate-induced changes in AC/cAMP signaling impact cell growth.
  • To identify the specific cell lines and mechanisms involved in phosphate-mediated signaling.

Main Methods:

  • Treatment of human osteosarcoma U2OS cells and other cell lines with inorganic phosphate (Pi).
  • Measurement of intracellular cAMP levels and AC activity.
  • Analysis of membrane protein expression.
  • Pharmacological inhibition of sodium-dependent phosphate transport.
  • Assessment of cell growth inhibition and rescue using cAMP-elevating agents (8-Br-cAMP, IBMX, forskolin).

Main Results:

  • Inorganic phosphate (Pi) treatment decreased intracellular cAMP levels and AC activity in U2OS cells, leading to cell growth inhibition.
  • These effects were specific to U2OS cells, as other cell lines showed different responses to Pi.
  • Pi-induced downregulation of AC/cAMP was associated with changes in membrane proteins of the AC system.
  • Inhibition of sodium-dependent phosphate transport blunted these effects.
  • cAMP-elevating agents prevented phosphate-induced cell growth inhibition.

Conclusions:

  • Phosphate acts as a signaling molecule, modulating cellular functions.
  • The AC/cAMP axis is a novel signaling pathway regulated by phosphate in U2OS cells.
  • Phosphate-mediated regulation of the AC/cAMP pathway influences cell growth, highlighting a new mechanism for phosphate signaling.

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