Enhanced expression of alpha 2,6-sialyltransferase ST6Gal I in cervical squamous cell carcinoma.

OBJECTIVE

Increased messenger ribonucleic acid (mRNA) expression of beta-galactoside alpha 2,6-sialyltransferase I (ST6Gal I) is important in squamous cell carcinoma (SCC) of the cervix. In many tissues, ST6Gal I is transcriptionally regulated through the use of promoters that originate in the mRNA species that diverge in the 5'-untranslated regions. To clarify the roles of ST6Gal I mRNA species in cervical SCC, we investigated their expression, including a "constitutive" promoter (placental or Y + Z form), "hepatic" promoter (H form), and a specific lymphoblastic promoter (X form), in normal and SCC tissues of the cervix using real-time quantitative reverse-transcription polymerase chain reaction (RT-PCR).

METHODS

Expression of the ST6Gal I species was investigated in normal cervical tissue samples (n = 38) and FIGO IB1 cervical SCC samples (n = 38) by relatively quantitative real-time RT-PCR, using primers designed for amplification of a portion of the coding region common to all mRNA species or ones for amplification of the placental transcript, the hepatic transcript, or lymphoblastic transcript.

RESULTS

ST6Gal I mRNA expression was significantly increased in cancerous tissues compared to that in normal tissues (P = 0.004, Mann-Whitney U test; P < 0.001, paired t test). Expression of the Y + Z form did not appear to be affected by cancer transformation, since it was detected at comparable levels in normal and cancerous tissues (P = 0.986), but H form expression was significantly enhanced in cancerous tissues compared to that in normal tissues (P < 0.001, Mann-Whitney U test and paired t test). Surprisingly, the X form could be detected in some patients with and without cancer, but the detection rate was significantly higher in patients with cancer (86.8% vs 52.6%, respectively; P = 0.021, Fisher's exact test). Although the X transcript was detected at a low level compared to the H and Y + Z transcripts, its expression was also significantly enhanced in patients with cancers compared to those without cancers (P < 0.001, Mann-Whitney U test and paired t test).

CONCLUSIONS

An increased level of hepatic transcripts may be important in cancer transformation because the transcripts contribute to enhance ST6Gal I expression in cancerous tissues.