Relatively High Expression Ratio of Sex Hormone‐binding Globulin Exon VII Splicing Variant to Wild‐type mRNA in Human Uterine Cervical Cancers

We have demonstrated the intracellular expression of sex hormone‐binding globulin (SHBG) exon VII splicing variant mRNA in human uterine cervical cancer using reverse transcription‐polymerase chain reaction‐Southern blot and DNA sequencing analyses. Analysis of the missing base pairs proved they corresponded to the entire exon VII, which is considered to encode a portion of the steroid‐binding site, suggesting that the steroid‐binding affinity of the variant protein might be different from that of the wild‐type SHBG. In uterine cervical cancers, the wild‐type mRNA levels were lower (P<0.1) and the ratio of the SHBG variant to wild‐type mRNA levels was higher (P<0.01) than in the normal cervix. In cervical adenocarcinomas, the wild‐type mRNA levels were higher (P<0.05) and the ratio of the SHBG variant to wild‐type mRNA levels was lower (P<0.05) than in cervical keratinizing squamous cell carcinomas. There was no difference in expression among the clinical stages of cervical cancers. These results suggest that a relative increase of intracellular variant SHBG protein in human uterine cervical cancers might be involved in the disruption of the normal estrogen dependence.