Human alpha2,3-sialyltransferase (ST3Gal II) is a stage-specific embryonic antigen-4 synthase.
Monosialosyl globopentaosylceramide (MSGb5), originally described as stage-specific embryonic antigen-4, is expressed in testicular germ cell tumors and in aggressive cases of human renal cell carcinoma (RCC). Clarification of the molecular mechanisms regulating synthesis of MSGb5 is very important to understand testicular carcinogenesis and the malignant progression of human RCC. For this purpose, we have investigated alpha2,3-sialyltransferase involved in the synthesis of MSGb5. We used the method of expression cloning combined with polymerase chain reaction targeted to sialylmotif to isolate a cDNA clone from RCC cell line ACHN library. The cloned cDNA was found to be identical to the previously cloned ST3Gal II in sequence. A soluble recombinant form of the protein in COS-1 cells showed an enzyme activity of alpha2,3-sialyltransferase toward globopentaosylceramide (Gb5) in addition to asialo-GM1 and GM1a. Transient transfection of COS-7 and ACHN cells with this cDNA induced an increase of MSGb5, whereas stable transfection of antisense ST3Gal II cDNA suppressed expression of MSGb5 in ACHN cells. The ST3Gal II mRNA level was increased in 7 of 8 RCC cell lines and in all six RCC tissues surgically obtained, although it was not necessarily consistent with the MSGb5 level in RCC cell lines. This study indicates that ST3Gal II is a MSGb5 (stage-specific embryonic antigen-4) synthase and that its increased expression level is closely related to renal carcinogenesis.
Saito
Seiichi
S
Department of Urology, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan. ssaito@uro.med.tohoku.ac.jp
Aoki
Hiroshi
H
Ito
Akihiro
A
Ueno
Seiji
S
Wada
Tadashi
T
Mitsuzuka
Koji
K
Satoh
Makoto
M
Arai
Yoichi
Y
Miyagi
Taeko
T
D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002240:Carbohydrate Sequence; D002292:Carcinoma, Renal Cell / Q000201:enzymology / Q000235:genetics; D003001:Cloning, Molecular; D016373:DNA, Antisense / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D005732:Gangliosides / Q000096:biosynthesis / Q000737:chemistry; D006028:Glycosphingolipids / Q000096:biosynthesis* / Q000737:chemistry; D006801:Humans; D007680:Kidney Neoplasms / Q000201:enzymology / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012799:Sialyltransferases / Q000235:genetics / Q000378:metabolism*; D055746:Stage-Specific Embryonic Antigens; D013736:Testicular Neoplasms / Q000201:enzymology / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase
D016373:DNA, Antisense; D018076:DNA, Complementary; D005732:Gangliosides; D006028:Glycosphingolipids; D012333:RNA, Messenger; D011994:Recombinant Proteins; D055746:Stage-Specific Embryonic Antigens; C025447:sialogangliosides; C066584:stage-specific embryonic antigen-4; D012799:Sialyltransferases; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase; C000722087:ST3GAL1 protein, human