title: Involvement of PI3-K in neuroprotective effects of the 1,25-dihydroxyvitamin D3 analogue - PRI-2191.
abstract: The active form of 1,25-dihydroxyvitamin D(3) prevents neuronal damage in vitro and in vivo , however, it induces also hypercalcemia and hyperphosphatemia. Side-chain-modified analogues of 1,25-dihydroxyvitamin D(3), which show low calcemic activity, may be potentially useful in the treatment of some neurodegenerative diseases. Previously, we have found that PRI-2191 more potently than 1,25-dihydroxyvitamin D(3) protects human neuroblastoma (SH-SY5Y) cells against hydrogen-peroxide-induced toxicity. In the present study, we evaluated effects of two other 1,25-dihydroxyvitamin D(3) analogues - PRI-1890 and PRI-1901 on the neuronal degeneration in the same cell model. In line with the previous study, 24-h incubation with hydrogen peroxide (0.5 mM) was toxic to cells, as evidenced by an enhanced efflux of lactate dehydrogenase into the culture medium, and these effects were prevented by PRI-1890 and PRI-1901 at concentration of 5, 50 and 500 nM. Comparing the neuroprotective effects of secosteroids, we found that all three analogues were efficient at lower concentration than 1,25-dihydroxyvitamin D(3) and among them the PRI-2191 showed the most evident concentration-dependent effect. In the second part of this study, an involvement of mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3-K), kinases which play a crucial role in neurodegenerative processes, in neuroprotective action of 1,25 dihydroxyvitamin D(3) and its the most potent analogue PRI-2191 has been investigated. The inhibitor of c-Jun N-terminal kinase (JNK)-MAPK (SP600125, 1 microM), inhibitor of p38-MAPK (SB-203580, 1 and 10 microM) and inhibitor of extracellular signal-regulated kinase (ERK)-MAPK (PD-98059, 15 and 30 microM) attenuated the hydrogen peroxide-induced toxicity. Moreover, PD-98059 (30 microM) enhanced neuroprotective effects of 1,25 dihydroxyvitamin D(3) but not that of PRI-2191. In contrast, the inhibitor of PI3-K (wortmannin, 10, 100 nM) did not affect hydrogen peroxide-induced cell damage itself, however, it significantly antagonized the effect of PRI-2191. On the other hand, wortmannin did not affect the neuroprotective effects of 1,25 dihydroxyvitamin D(3) This suggests that the activation of PI3-K/Akt signaling pathway plays an important role in the mechanism of inhibitory action of PRI-2191 on hydrogen peroxide-evoked toxicity in SH-SY5Y cells. Furthermore, these data point to differential involvement of ERK-MAPK and PI3-K in neuroprotective effects of 1,25 dihydroxyvitamin D(3) and its low-calcemic analogue - PRI-2191.
authors.affiliation: Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, PL 31-343 Kraków, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Regulska
authors.forename: Monika
authors.initials: M
authors.lastname: Leśkiewicz
authors.forename: Bogusława
authors.initials: B
authors.lastname: Budziszewska
authors.forename: Andrzej
authors.initials: A
authors.lastname: Kutner
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Basta-Kaim
authors.forename: Marta
authors.initials: M
authors.lastname: Kubera
authors.forename: Lucylla
authors.initials: L
authors.lastname: Jaworska-Feil
authors.forename: Władysław
authors.initials: W
authors.lastname: Lasoń
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D002117:Calcitriol / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor; D004100:Dihydroxycholecalciferols / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000502:physiology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D004100:Dihydroxycholecalciferols; D018696:Neuroprotective Agents; C108254:PRI 1901; C023850:1 alpha,24-dihydroxyvitamin D3; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D019869:Phosphatidylinositol 3-Kinases; D002117:Calcitriol; D000077191:Wortmannin