Objective: To investigate the post-transcriptional regulation of p21WAF1/CIP1 by p53. Methods: The MDA-MB-468 cells have endogenous mutant p53 and the MCF7 cells lines have wtp53. Recombinant p53 expression and p21WAF1/CIP1 induction were detected by Western blot analysis. Northern blot analysis was carried out to examine whether changes in p21WAF1/CIP1 protein levels in MCF7 cells treated with AdCMVp53 are reflected at the mRNA level. Flow cytometric analysis of MCF7 cells following overexpression of recombination. Results: The ratio of p53: p21WAF1/CIP1 was below 1 at the early stages of AdCMVp53 infection, but increased to 1.6 by day 3 and to 9.7 by day 5 post-infection. As expected, p21WAF1/CIP1 expression was not detectable in MDA-MB-468 cells despite the presence of high levels of mutant p53 protein. The G1/S ratios in untreated controls and AdCMVβgal infected MCF7 cells were 1.10 and 1.35, respectively. By Northern blot analyzing the p21WAF1/CIP1: GAPDH ratios at different time points against the ratio at time point 0, a maximum 3-fold induction of p21WAF1/CIP1 mRNA expression relative to untreated control was observed on day 1 post-infection. The flow cytometric analysis indicated that MCF7 cells infected with AdCMVp53 undergo G1 arrest at both time points studied, with G1/S ratios ranging from 5.54 at day 1 to 5.65 at day 7. The G1/S ratios in untreated controls and AdCMVβgal infected MCF7 cells were 1.10 and 1.35, respectively. Conclusion: This studydemonstrated that p53 could regulate p21WAF1/CIP1 gene expression at both the transcriptional and post-transcriptional levels in MCF7 cells. The latter mechanism may be involved in or be responsible for, the induction of cell cycle arrest by transcription-defective mutants of p53.

BACKGROUND:Ferula sinkiangensis K.M. Shen is composed of volatile oil, resin and gum that have the anti-inflammatory, anti-alergic, antispasmodic and analgesic effects. But its analgesic mechanism is unclear. OBJECTIVE: To observe the effect ofFerula sinkiangensis K.M. Shen on heat pain, mechanical pain, Fos protein expression and astrocyte activation in spinal cord of rats with neuropathic pain. METHODS: Eighty adult Sprague-Dawley rat models of chronic sciatic nerve injury were randomly divided into five groups and then intragasticaly administeredFerula sinkiangensis K.M. Shen at low, moderate and high doses (0.075, 0.15, 0.30 g/kg), celecoxib or physiological saline. Heat pain and mechanical pain were measured at 1 day before operation and at 1, 2, 3, 5, 7, 14 days after operation. The spinal cord tissue at S4-5 segments was harvested and Fos protein expression and astrocyte activation in the spinal cord of rats were observed by immunohistochemical staining method. RESULTS AND CONCLUSION: After 1 and 5 days of medication, behavioral pain scores of rats in the low-, moderate-, and high-doseFerula sinkiangensis K.M. Shen groups were significantly higher than that in the physiological saline group (P < 0.01). The largest reduction in heat pain threshold was measured in the moderate-doseFerula sinkiangensis K.M. Shen group compared to the other groups (P < 0.01). The most significant reduction in rat mechanical pain threshold was measured in the high-doseFerula sinkiangensis K.M. Shen group than in the other groups (P < 0.01). At each time point post-operation, the number of Fos protein-positive cels in the low-, moderate- and high-doseFerula sinkiangensis K.M. Shen and celecoxib groups was significantly lower than that in the physiological saline group (P < 0.05); the number of Fos protein-positive cels in the moderate- and high-doseFerula sinkiangensis K.M Shen groups was significantly higher than that in the celecoxib group (P< 0.05). At each time point post-operation, the number of astrocytes in the spinal cord tissue of rats in the high-doseFerula sinkiangensis K.M. Shen and celecoxib groups was significantly lower than that in the physiological saline group (P< 0.05). There was significant difference in the number of astrocytes between the moderate- and high-doseFerula sinkiangensis K.M shen groups and celecoxib group (P< 0.05). These results confirm thatFerula sinkiangensis K.M. Shen may effectively aleviate the neuropathic pain of rats, and the mechanism of which may be related to the activation of Fos protein and astrocytes in the spinal cord.