Functional Assay On The Colorectal Cancer Metastasis-related Protein ZNF238

ZNF238(Zinc Finger Protein238) is one kind of C2H2zinc finger protein, which acts as a transcriptional activator or transcriptional repressor. However, ZNF238as a transcription factor lacks the common NLS (Nuclear Localization Signal). There are no relevant reports about its nucleation mechanism. It has been reported that ZNF238could inhibit brain tumor, thus it is considered to be a tumor suppressor. However, after analyzing the expression data from open-access database, we found that ZNF238has significantly high expression in colorectal cancers, suggesting that ZNF238may promote colorectal cancer progress.We detected ZNF238expression levels by qPCR in multiple colorectal cancer cell lines. The result showed that the expression level of ZNF238in metastatic tumor cells was higher than that of non-metastatic tumor cells. After reducing the expression of ZNF238in HT29cells by RNAi, we found the downexpression of ZNF238could significantly inhibit cell invasion and migration in vitro, indicating that ZNF238could promote the invasion and migration of colorectal cancer cells.We assumed that SUMOylation maybe a possible regulatory mechanism of ZNF238in different cancer types. On one hand, SUMOylation could regulate transcription factors as a regulatory switch, on the other hand, many researchers have discovered that SUMOylation has the ability to transfer many non-nuclear proteins into the nucleus to exercise their related functions. Therefore, we studied the SUMOylaiton of ZNF238. The SUMOylation site of ZNF238was predicted by SUMOplot, in which five putative SUMOylation sites were found. We discovered that out of the five putative SUMOylation sites, two particular sites have the highest probability of SUMOylation, therefore, our study focused on these two sites:K273and K499sites. Exogenous ZNF238subcellular localization by immunofluorescence assay analysis revealed that the protein is indeed expressed in the nucleus, but the distribution of its SUMOylation site mutant protein has not changed. We also proved that ZNF238could be modified by SUMO1by Co-IP experiment, but its modification sites are not the predicted sites. Futher experiments will be performed to locate the SUMOylation sites and its effects on cancer phenotype.