Differential expression of telomerase activity in human cervical cancer and cervical intraepithelial neoplasia lesions.

PURPOSE: Telomeres are tandem arrays of repeated DNA sequences located at the ends of eukaryotic chromosomes, and are synthesized by the enzyme telomerase. Loss of telomeric DNA may play an important role in the development of human cancers. However, very little is known about the status of telomerase during human cervical cancer development. PATIENTS AND METHODS: Telomerase activity was measured by telomere repeat amplification protocol (TRAP) assay in 24 cervical cancers, one carcinoma in situ (CIS), and 20 cervical intraepithelial neoplasia (CIN) lesions. Adjacent nontumor cervical tissue from the same 24 cervical cancer patients and normal cervical tissues from 11 control individuals also were examined for the presence of telomerase activity. RESULTS: Twenty two of the 24 (91.7%) cervical cancer specimens and the single CIS tissue were strongly positive for telomerase activity. Relatively weak but distinctive telomerase activity also was detectable in one of four CIN-I (25%), two of eight CIN-II (25%), and two of eight CIN-III (25%), respectively. However, telomerase activity was not found in the 24 corresponding nontumor cervical tissues from the same cervical cancer patients and the 11 normal cervical tissues from control individuals. CONCLUSION: The majority of cervical cancers contain strong telomerase activity. Significant proportions of noncancerous CIN tissues also contain telomerase activity, although weaker than that in cervical cancer. It seems that there is a progressive increase of telomerase activity in association with an increased degree of cervical malignancy. These results seem to suggest that the expression of telomerase may play a crucial role in cervical cancer carcinogenesis.

Detection of human papillomavirus mRNA and cervical cancer cells in peripheral blood of cervical cancer patients with metastasis.

PURPOSE: To determine the presence of cervical cancer cells in circulating peripheral blood of stage IVb cervical cancer patients with metastasis to distant organs. PATIENTS AND METHODS: Cervical cancer tissue from 15 stage IVb cervical cancer patients with metastasis were analyzed for the presence of human papillomavirus (HPV) type 16 DNA by nested polymerase chain reaction (PCR). The presence of transcriptional products of the HPV type 16 E6-transforming gene in the peripheral blood of the same 15 cancer patients was analyzed by reverse transcription and PCR. Cervical tissues and peripheral-blood specimens from 12 normal healthy individuals served as controls. RESULTS: Thirteen of 15 (86.7%) cervical cancer tissues from same number of patients were found to contain HPV type 16 DNA. Peripheral-blood specimens from 12 of 13 (92.3%) cervical HPV DNA-positive patients were found to contain HPV-specific mRNA detectable by reverse transcription (RT) and PCR. Cervical tissues from all 12 normal controls were HPV-free. None of the peripheral-blood specimens from two cervical HPV-negative cancer patients and 12 normal controls contained detectable amounts of mRNA of HPV type 16 E6-transforming gene. CONCLUSION: The most likely source of the HPV-specific mRNA detected in the peripheral blood of cervical cancer patients with metastasis is the cervical cancer cells derived from or shed from the cervix. The presence of HPV E6 mRNAs in peripheral blood may be a sensitive indicator of circulating cervical cancer cells. If PCR positivity is proven to be able to predict disease progression reliably, these findings may have clinical applications in the treatment of cervical and many other cancers.

Lack of mutation in tumour-suppressor gene p53 in gestational trophoblastic tumours.

The objectives of this study were to better our understanding of the carcinogenesis of gestational trophoblastic tumours and to investigate the possible presence of mutational alteration of the p53 tumour-suppressor gene in these tumours. Amplification-based direct DNA sequencing was performed on 14 hydatidiform moles, six invasive moles, eight choriocarcinomas and ten normal early placental tissues. No mutation in exons 5-8 was detected in any of these 38 tissue specimens. These results suggest that a mutation in p53 tumour suppressor either does not exist or is a very rare event in gestational trophoblastic tumours. The gestational trophoblastic tumours probably involve a tumour-suppressor gene other than p53 gene or may follow a completely different pathway to their malignant phenotype.

Human papillomavirus type 18 DNA in gestational trophoblastic tissues and choriocarcinomas.

The objectives of our study were to better understand carcinogenesis of gestational trophoblastic tumors and to investigate the possible presence of human papillomavirus types 16 and 18 DNA sequences in these tumors. Amplification-based DNA methodology was used on 11 hydatidiform moles, 5 invasive moles, 8 choriocarcinomas and 9 normal early placental tissues. Human papillomavirus type 16 DNA was not found in any of these tissues. Although human papillomavirus type 18 DNA was also not found in the 9 normal placentas and 5 invasive moles, it was present in 2 of the 11 (18%) hydatidiform moles and in 4 of the 8 (50%) choriocarcinomas.

Genital human papillomavirus infections in young women with vulvar and vestibular papillomatosis.

Possible involvement of human papillomaviruses (HPV) in the development of vulvar and vestibular papillomatosis was investigated by using PCR to determine whether HPV DNA was present in lesions. Fourteen of 272 (5.1%) young women studied were found on gross and histological examination to have vulvar or vestibular papillomatosis. HPV DNA sequences were detected in cervicovaginal lavage specimens of 2 of 14 (14.3%) papillomatosis patients and 1 of 17 (5.9%) matched individuals in the control group without lesions. The difference in HPV prevalence between these two groups was not statistically significant (x2 = 0.51, p > 0.2). Furthermore, none of the 14 vulvar or vestibular papillomatosis biopsy tissues contained HPV DNA. The results suggest that vulvar and vestibular papillomatosis has an etiology other than HPV infection.

Fetal cells in the maternal circulation during first trimester in pregnancies.

To investigate the presence of fetal cells in the maternal circulation during early pregnancy, the polymerase chain reaction was used to test the presence of human Y chromosome-specific ZFY and SRY gene DNA sequences in maternal peripheral blood specimens from 19 women carrying male fetuses and 12 women carrying female fetuses. The presence of fetal cells was suggested as early as 6 weeks gestation in 1 of the 19 women bearing male fetuses. Fetal cells were present in the maternal circulation of 15 of the 19 women by 9 weeks gestation, and in only 1 of the 19 were fetal cells not detected until the 12th week after conception. These results suggest that identification of fetal cells in the maternal circulation is possible with a properly designed and executed polymerase chain reaction. However, there was considerable variation with respect to when these fetal cells first became detectable during pregnancy. These fetal cells are potentially a valuable source of material for biochemical and genetic studies of the fetuses.

Inhibition of in vitro enzymatic DNA amplification reaction by ultra-violet light irradiation.

Ultra-violet light irradiation of containers and components used in in vitro DNA amplification reactions catalyse by Taq DNA polymerase is a simple and effective method to reduce carry-over contamination and can reduce false-positive results. However, we found that prolonged exposure of water in polypropylene microcentrifuge tubes to u.v. light can result in reduction of amplification efficiency by at least two orders of magnitude when these water specimens are used in amplification reaction mixtures. Although the mechanism that causes this inhibition of DNA amplification is unclear now, the results seem to suggest that u.v. irradiation for routine anti-contamination purposes should be used with caution.

Lack of mutational alteration in the conserved regions of ZFY and SRY genes of 46,XY females with gonadal dysgenesis.

To further our understanding of the mechanism of action of regulatory and structural genes involved in human sex determination, we have examined three sex-reversed 46,XY females and two of their normal fathers for any mutational alteration in ZFY and SRY genes, using polymerase chain reaction and single-strand conformation polymorphism and by subsequent DNA sequencing. We could not find any mutation in the ZFY and SRY genes of these patients and their fathers. The results seem to suggest that although ZFY and SRY may be required for initiation of testis differentiation and male sex determination, sex-reversed females may predominantly result from alterations in genes either downstream or secondary to ZFY or SRY.