OBJECTIVETo investigate whether or not adaptive response of hPARP-1 protein normal and deficient cells is induced by low dose of hydroquinone (HQ), and to analyze the relationship between the adaptive response and micronuclei formation, and cell cycle alteration in human embryo lung fibroblasts (HLF), so as to elucidate the mechanism of adaptive response.

METHODSHLF, HLFC and HLFP cells pretreated with low concentration were retreated by high concentration of HQ. Cellular viability, the rate of micronuclei and abnormal nuclei, cell cycle and DNA strand break were determined.

RESULTSThe tolerance to 80.0 micromol/L concentration of HQ was enhanced when HLF, HLFC and HLFP cells were pretreated with HQ from 0.001 - 0.050 micromol/L. There were varying degrees of micronuclei and abnormal nuclei in three cells pretreated with low concentration of HQ and then retreated with high concentration of HQ; the cell numbers of G1, G2, S phase in cell cycle were obviously different. When compared with only high attack dose, the micronuclei rate and abnormal nuclei rate of HLF, HLFC and HLFP decreased by pretreatment with HQ at high concentration (P < 0.05), meanwhile increased by pretreatment with HQ at low concentration (P < 0.05). HLF, HLFC and HLFP showed blockage in G2 phase when pretreated with HQ at 0 approximately 0.05 micromol/L, but HLFP showed blockage in G1 phase, and in S phase at 1.0 and 2.0 micromol/L.

CONCLUSIONThe level of adaptive response of hPARP-1 protein deficient cells was lower than normal cell, suggesting that hPARP-1 protein may play an important role in the adaptive response of cells, which may be related with the regulation of cell cycle.