| Gankyrin is an recently discovered oncoprotein. Structurally, human Gankyrin protein contains 226 amino acids and is composed of seven 33-amino acids ankyrin repeats. Gankyrin is a non-catalytic subunit of the 19S regulatory particle of the 26S proteasome and combines with the S6bATPase specially.Initially the expression level of Gankyrin was found higher in HCC (hepatoma carcinoma cells) than in normal hepatoma cells. Since then, the function of Gankyrin has been investigated. Reseachers found that Gankyrin could interact with anti-oncoprotein RB and promote its degradation. Gankyrin could enhance the activity of unbiquitin E3 ligase MDM2, thus facilitating the degradation of P53. Also increased Gankyrin was found in Ras-transformated NIH3T3 cells, implying that Gankyrin participates in the cell transformation process. Other reports displayed that Gankyrin could interact with Cdk4 (cyclin-dependent kinase 4), an antagonistic factor of p16INK4A and p18INK4C2. Gankyrin could also interact with RelA and inhibit the activity of NF-kappaB signal pathway.The studies mentioned above hint that Gankyrin participates in several signal pathways. It plays an important role in tumors especially in liver cancer and colon carcinoma. However, the melecular mechnisms by which Gankyrin exerts its roles, especially in cell proliferation, metabolism and apoptosis, are largely unkown.To explore the physiological and pathological functions of Gankyrin in tumor cells and to search for the signal pathway which Gankyrin participates in, the effect of Gankyrin knockdown on gene expression profile of SW480 human colon carcinoma cells was examined by high-througput microarrays. Combined with multiple data analytical methods, we have found some possible pathways that may be affected by Gankyrin. 78 significantly altered genes were screened out, some of which were selected randomly to be validated by RT-PCR and Real-Time PCR.In a conclusion, expression profile microarray is an effective approach for gene function study, and our screening results provide basis and clues for thoroughly understanding the function of Gankyrin, especially in the signal transduction network. |
