OBJECTIVE To investigate the potential mechanism of epigallocatechin gallate （EGCG） enhancing the sensitivity of hepatocellular carcinoma （HCC） cells to lenvatinib based on the phosphoinositide 3-kinase （PI3K）/protein kinase B （Akt） signaling pathway. METHODS Five human HCC cell lines （HepG2， Huh-7， SMMC-7721， SNU-368 and SNU-739） were used to evaluate the effects of lenvatinib alone and in combination with EGCG on survival rates， clone number， proliferation rate， invasion number and the expressions of mRNAs and proteins related to the PI3K/Akt signaling pathway. The PI3K activator insulin-like growth factor-1 （IGF-1） was introduced to investigate the effect of activating the PI3K/Akt signaling pathway on the sensitization effect of EGCG. RESULTS Compared with the control group， lenvatinib （10 μmol/L） and different concentrations of EGCG+ lenvatinib （1， 5 and 10 μg/mL EGCG+10 μmol/L lenvatinib） significantly reduced the survival rates and clone numbers of all five HCC cell lines in a dose-dependent manner （P＜0.05）. Lenvatinib （10 μmol/L） and EGCG+lenvatinib （10 μg/mL EGCG+10 μmol/L lenvatinib） also markedly inhibited the proliferation rate and invasion numbers of these cells， and decreased the mRNA expressions of PI3K， Akt， mammalian target of rapamycin （mTOR）， P70S6K and 4EBP， and the phosphorylation levels of PI3K and Akt， as well as the protein expressions of mTOR and B cell lymphoma-2 （Bcl-2） in HepG2 cells or all five HCC cells； conversely， the mRNA and protein expressions of phosphatase and tensin homologue deleted on chromosome 10（PTEN）， and the protein expressions of caspase-3 and cleaved caspase-3 were significantly upregulated， with more pronounced effects observed in the EGCG+lenvatinib group than in the lenvatinib group （P＜0.05）. Compared with the lenvatinib group and the EGCG+lenvatinib group， the clone number， proliferation rate and invasion number of HepG2 cells in the EGCG+lenvatinib+IGF-1 group （10 μg/mL EGCG+10 μmol/L lenvatinib+50 ng/mL IGF-1） were significantly increased （P＜0.05）. CONCLUSIONS EGCG can enhance the sensitivity of HCC cells to lenvatinib， and its underlying mechanism may be related to the inhibition of the activation of PI3K/Akt signaling pathway activation.

Objective: To investigate the influence of extremely low-frequency magnetic field on periodical expression of cryptochrome (Cry) gene in mouse embryonic fibroblast NIH3T3 cells. Methods: The NIH3T3 cells were divided into magnetic field group and sham-exposure group. The NIH3T3 cells in the magnetic field group were stimulated by horse serum and then exposed to an extremely low-frequency magnetic field (50 Hz and 0.3 mT) for 48 hours, and those in the sham-exposure group were also stimulated by horse serum and then exposed to a coil for 48 hours. The NIH3T3 cells were collected, total RNA was extracted, and cDNA was obtained via reverse transcription. Real-time fluorescent quantitative RT-PCR was used to measure the changes in transcription cycles of Cry and Period genes in both groups. Results: There was no significant difference in the proliferation rate at 0, 12, 24, and 48 hours of exposure between the two groups (P>0.05) . Both sham-exposure group and magnetic field group showed a rhythmic change in the expression of Cry gene, and compared with the sham-exposure group, the magnetic field group had a significantly shortened circadian rhythm of Cry gene in NIH3T3 cells (t=2.57, P<0.05) . Both groups had rhythmic and periodical expression of Period gene and there was no significant difference between the two groups (t=0.70, P>0.05) . Conclusion Extremely low-frequency magnetic field can significantly shorten the circadian rhythm of Cry gene in mouse embryonic fibroblasts, while there is no significant change in the circadian rhythm of Period gene.