Alterations in Promoter Usage and Expression Levels of Insulin-like Growth Factor-II and H19 Genes in Cervical and...

The biallelic expression of insulin-like growth factor-II (IGF2) and H19 has been reported to be associated with the progression of several tumors. Here, the promoter usage and expression levels of IGF2 and H19 are reported to be altered in cervical and endometrial cancers showing loss of imprinting (LOI).

The imprinting status of IGF2 and H19 was examined in 32 cervical carcinomas, their matched normal tissues, 13 endometrial cancer and 33 normal endometrial tissues.

The LOI of IGF2 was observed in 7 of 18 (39%) and 1 of 13 (8.3%) informative cervical carcinomas and informative endometrial cancers, respectively. The LOI of the H19 gene was detected in 5 of 14 (36%) and in all 11 (100%) informative cervical carcinoma cases and informative endometrial cancer cases, respectively. The use of promoter P1 was observed in the LOI tumors of IGF2, but not in the tumors showing maintenance of IGF2 imprinting (MOI), or in cervical and endometrial cancers. Unlike MOI tumors, some LOI tumors revealed a lack of IGF2 transcription from the promoter P3. The LOI tumors of IGF2 showed increased expression of the IGF2 level, but a down-regulation of the H19, relative to normal tissues, whereas the MOI tumors revealed no significant alterations.

These results suggest that the promoter P1 could be involved in the biallelic expression of IGF2, and that the altered expression of the IGF2 and H19 levels might be associated with the progression of cervical and endometrial cancers that exhibit biallelic IGF2 expression.