Phenotypic changes in the variant of 4T1 cell line
Raja, Geraldine Vidhya
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By targeting and preventing cancer metastasis, the lethality of the disease can be decreased so that it would be curable. The primary goal of this research was to further understand the metastatic process and understand the role of the Thomsen-Friedenreich antigen in metastasis. 4T1, a TF-Ag expressing metastatic mouse mammary tumor cell line and related cell lines with different metastatic potentials were compared. Preliminary work analyzing the differential gene expression in the metastatic and the nonmetastatic cell lines using the glycogene chip indicated a differential expression of several genes related to sialic acid. Of particular interest was the downregulation of the gene ST3Gal1 in the metastatic cell line 4T1 when compared to the nonmetastatic cell line 4T07. ST3Gal1 codes for a sialyltransferase which would add a sialic acid in a 2-3 position to the TF-Ag. This addition would potentially block the interaction of the TF-Ag to adhesion sites for metastasis. The alteration of this gene in these two cell lines lead to the hypothesis that by increasing the expression of the sialyltransferase genes in the metastatic cell line, the metastatic potential may be drastically reduced. The gene coding for the sialyltransferase ST3Gal1 was cloned from the nonmetastatic cell line 4T07 and transfected into the metastatic cell line 4T1. The passages and transfection, lead to the creation of a variant of the 4T1 cells called 4T1 Miten. The aim of this research is to study the metastatic potential of 4T1 Miten cell line in vivo and to study in vitro the various physical properties that contribute to the altered metastatic potential of the cells. Initial studies indicated an upregulation of the ST3Gal1 in the transfected cell line; however the 4T1 cell line has previously been shown to change with time in culture. Gene chip analysis at the end of the studies indicated differences in several genes that have been implicated in cancer, but unfortunately, no upregulation of the ST3Gal1. The impact of each one of the genes which were upregulated and their role in the phenotypic changes will be discussed.