Telomerase assay and HPV 16/18 typing as adjunct to conventional cytological cervical cancer screening

OBJECTIVE

This study aims at exploring the potential use of telomerase activity assay and typing of human papillomaviruses (HPV) 16 and 18 in improving the identification of high-grade cervical intraepithelial neoplasia (CIN).

METHODS

From 86 women with normal cervical smears and from 114 patients with abnormal cervical smears cervical scrapings were collected. The telomerase activity was assayed using the Telomerase Repeat Amplification Protocol, and HPV was detected using consensus primers and specific primers for HPV 16 and HPV 18.

RESULTS

HPV 16 in cervical scrapes was significantly associated with high-grade squamous epithelial lesions on cytology and with high-grade CIN, i.e., CIN 2/3 on biopsy. The detection of HPV 18 or telomerase activity had no significant association with high-grade squamous intraepithelial lesions or high-grade CIN.

CONCLUSION

The use of the telomerase activity assay in cervical scrapes, unlike HPV 16 typing, did not improve the detection of high-grade CIN.

Current understandings of the molecular genetics of gestational trophoblastic diseases

Gestational trophoblastic disease (GTD) is a heterogeneous group of diseases characterized by abnormally proliferating trophoblastic tissues. This includes partial and complete hydatidiform moles, invasive mole, choriocarcinoma and placental site trophoblastic tumour. Cytogenetic studies revealed that hydatidiform moles contain either solely (as in complete moles) or an excess (as in partial moles) of paternal contribution to the genome. Genomic imprinting is believed to play a pivotal role in the pathogenesis of hydatidiform moles. However its precise role and mechanism remains poorly understood. Hydatidiform mole carries a potential of malignant transformation. Similar to other human cancers, malignant transformation in gestational trophoblastic tumours is likely a multistep process and involves multiple genetic alterations including activation of oncogenes and inactivation of tumour suppressor genes. In addition, expression of telomerase activity, altered expression of cell--cell adhesion molecules and abnormal expression of matrix metalloproteinases have also been reported in GTD. These represent disruption of the delicate balance and regulation of cellular processes including proliferation, differentiation, apoptosis and invasion. The significance of these alterations in the pathogenesis and malignant transformation of gestational trophoblastic diseases is reviewed in this paper.