Pifithrin-α (PFTα) HBr

Pifithrin-α inhibits p53-dependent transactivation of p53-responsive genes in ConA cells. Pifithrin-α (10 μM) inhibits apoptotic death of C8 cells induced by Dox, Taxol, cytosine arabinoside. Pifithrin-α inhibits p53-dependent growth arrest of human diploid fibroblasts in response to DNA damage but has no effect on p53-deficient fibroblasts. Pifithrin-α may modulate the nuclear import or export (or both) of p53 or may decrease the stability of nuclear p53. ^[1] Pifithrin-α (100-200 nM) completely suppresses the camptothecin-induced increase in the level of p53 DNA binding as well as the p53-responsive gene Bax in hippocampal cell. Pifithrin-α also decreases the basal level of p53 DNA-binding activity. Pifithrin-α (200 nM) protects cultured hippocampal neurons against death induced by DNA-damaging agents. Pifithrin-α (200 μM) stabilizes mitochondrial function, suppresses caspase activation and protects cultured hippocampal neurons against death induced by glutamate and amyloid β-peptide. ^[2] Pifithrin α, in addition to p53, can suppress heat shock and glucocorticoid receptor signaling but has no effect on nuclear factor-kappaB signaling. Pifithrin α (10 μM) reduces activation of heat shock transcription factor (HSF1) and increases cell sensitivity to heat. Pifithrin α (10 μM) reduces activation of glucocorticoid receptor and rescues mouse thymocytes from apoptotic death after treatment in HeLa cells. ^[3] PFTalpha blocks p53-mediated induction of p21/Waf-1 in human embryonic kidney cells. ^[4]

Pifithrin-α (2.2 mg/kg i.p.) treatment completely rescues mice (C57BL and Balb/c) of both strains from 60% killing doses of gamma irradiation (8 Gy for C57BL and 6 Gy for Balb/c). Pifithrin-α-injected mice lost less weight than irradiated mice that are not pretreated with the Pifithrin-α. Pifithrin-α (2.2 mg/kg) abrogates p53-dependent regulation of DNA replication after whole-body gamma irradiation in mice. ^[1] Pifithrin-α (2 mg/kg i.p.) 30 min prior to middle cerebral artery occlusion treatment of mice reduces ischemic brain injury and protects hippocampal neurons against excitotoxic injury. ^[2] Pifithrin α (3.6 μg/kg i.p.) inhibits Dex-induced degeneration of the thymus in mice. ^[3] Pifithrin α (2 mg/kg) results in a significantly lower degree of motor disability in rats receiving transient occlusion of the middle cerebral artery as compared with controls. Pifithrin α-treated animals has less motor disability and smaller infarcts when the drug is administered up to an hour after stroke onset. Pifithrin α results in significantly lower motor disability scores in rats than in the vehicle-treated animals at 7 days post-op. Pifithrin α results in significant reduction of apoptosis in rats as indicated by Tunel and caspase 3 staining. ^[5]

• Cell lines

  HCT116 and Hela cells

• Concentrations

  ~10 μM

• Incubation Time

  48 hours

• Method

  At the end of cell treatments, the number of attached cells is estimated by staining with 0.25% crystal violet in 50% methanol, followed by elution of the dye with 1% SDS. Optical density (530 nm) reflecting the number of stained cells is determined with a Bio-Tek EL311 microplate reader. Cell viability in suspension of short term culture of primary thymocytes is determined by their staining with 0.1% of methyl blue and microscopic counting of blue (dead) cells.

• Animal Models

  C57BL and Balb/c mice

• Dosages

  2.2 mg/kg

• Administration

  Intraperitoneal injection