RESUMO
Primary hepatocellular carcinoma(HCC) is one of the common malignant tumors in China. In our previous work, a gene named fup1(function-unknown protein 1) was isolated that was expressed differently in HCC and in normal liver. We assumed that it might be a candidate oncogene for the HCC. The fup1 gene had a ORF of 1 233 bp, encoding a protein with M(r) of 46 kD and isoelectric point of 5.48. The sequence characteristics showed its possible localization in nuclei. Northern blots showed that this gene was weakly expressed in many types of human tissues, except in the heart, implying its tissue-specific expression pattern. MTT assay of the NIH 3T3 cells transfected with this gene in the form of recombinant eukaryotic expression plasmid showed its enhancing role to cellular proliferation.
RESUMO
Preliminary investigation on the mechanism of the growth inhibition by recombinant epiregulin(EPI)of epidermal carcinoma cell A431 is reported. Northern blotting indicated that the mRNA level of cyclin dependent kinase(CDK)inhibitor, p21(WAF1/CIP1), was increased significantly after stimulation of the recombinant epiregulin protein. Luc reporter revealed that STAT1 could bind the promoter region of p21 in response to the EPI signal. Flow cytometry assay showed that the EPI-induced growth inhibition was not related to the apoptosis. The above results indicate that the EPI-induced cell growth inhibition might result from the STAT1-stimulated expression of p21, leading to the G1 arrest.
RESUMO
Human epiregulin cDNA was amplified from the lung cancer cell line A549 using RT-PCR. After adding 6 His codon to its 3' end, it was cloned into a high efficient secretive Escherichia coli system with alkaline phosphatase promoter(phoA promoter)constructed in our lab and induced for expression. The product was purified one-step by Ni-NTA column. Amino acid sequence analysis revealed the identity of our product with that previously reported. The product showed strong proliferative effect on fibroblast cell line Balb/c3T3 and growth inhibitory effect on epithelial carcinoma cell line A431.
