Mitochondrial DNA (mtDNA) content in ovarian carcinomas was assessed by quantitative PCR. Results show that mtDNA content in tumour cell was significantly higher than that in normal ovary. Change in mtDNA content was not related with patients' age or tumour stages. However, the average mtDNA copy number in pathological low-grade tumours was over two-fold higher than that in high-grade carcinomas (P ¼ 0.012). Moreover, type I carcinomas also had a significantly higher mtDNA copy number than in type II carcinomas (P ¼ 0.019). Change in mtDNA content might be an important genetic event in the progression of ovarian carcinomas.
Cervical cancer is the commonest lower genital tract cancer found among Hong Kong Chinese. Human papillomavirus (HPV) infection has been found in over 80% of cervical cancers locally (Ngan et al, 1997). HPV plays an important role in cervical cancer due to degradation of p53 by the HPV E6 protein via the ubiquitine pathway (Werness et al, 1990). Storey et al (1998) found that women with homozygous arginine-72 (HA72) in p53 have a sevenfold increase in the risk of cervical cancer, perhaps because HA72 is more susceptible to E6-mediated degradation. However, subsequent studies in three Caucasian populations and one Japanese population have failed to support their findings (Hayes et al, 1998;Lanham et al, 1998;Minaguchi et al, 1998;Rosenthal et al, 1998). Since the frequency of p53 polymorphism varies amongst populations dwelling at different latitudes (Beckman et al, 1994), and Hong Kong is nearer the equator than the four reported studies, this study aims to determine the risk of cervical cancer in women with HA72 in p53 in Hong Kong Chinese. MATERIALS AND METHODS DNA samplesOne hundred and two patients with cervical cancer and 68 women with normal cervices were studied. DNA samples (stored at -70°C) left from a previous study on p53 and HPV in cervical cancer (Ngan et al, 1997) were used in this study. PCR amplification of p53 codon 72 polymorphic allelesp53 arginine and proline sequences were separately amplified from each sample with primers as described by Storey et al (1998). Polymerase chain reaction (PCR) was done in a volume of 25 µl containing 100 ng total cellular DNA, 200 µM of each deoxynucleotide triphosphate, 0.625 U of Ampli Taq DNA polymerase (Perkins-Elmer Cetus), 1 ϫ reaction buffer containing 1.25 mM magnesium ion. PCR was carried out in a Thermal Cycler (PerkinElmer Cetus) under conditions as follows: 40 cycles at 94°C for 30 s, 60°C for 30 s and 72°C for 30 s. The resulting PCR products were run in a 3% agarose gel and made visible under UV by ethidium bromide staining. The arginine PCR product was 141 bp and the proline PCR product was 177 bp. Detection of HPVResults of HPV 16 and 18 from a previous study (Ngan et al, 1997) were used. The procedure used to detect HPV 16 and 18 E6 was essentially that described previously (Ngan et al, 1994). Briefly, DNA was extracted and subjected to two PCR assays using specific primers for HPV 16 and HPV 18 E6. PCR products were run on 4% agarose gels and blotted onto nylon membranes and hybridized with specific probes to HPV 16 and 18 E6 products. DNA from Caski and Hela were used as positive controls for HPV 16 and 18 respectively, and DNA derived from the C33 cell line and water were used as negative controls. Statistical analysisChi-square test was used to analyse nominal data. A P-value of < 0.05 was considered significant. RESULTSHPV 16 or 18 E6 was detected in 78 samples (76.5%) of cervical cancer. Frequencies of arginine and proline p53 alleles in normal cervices and cervical cancer are shown in Table 1. In normal cervical tissue, 22% had HA72. Thi...
78 unrelated X chromosomes from Southern Chinese (56 normal and 22 haemophiliac) were studied. DNA was restricted by Bel I, Bgl I or Taq I and hybridized to 3' factor VIII:C cDNA probe (5 kb, Chiron) or St 14.1 probe(3 kb, Oberle &Mandel) by standard techniques. The intragenic Bel I polymorphic site was positive in 82%, while Bgl I polymorphic site was positive in all. Thus, 29.5%(2 x×0.82 × 0.18) of Chinese females carried the Bel I polymorphism. Asto the Taq I polymorphism in the closely linked DXS52 DNA segment, the incidences for the various alleles were :System I - allele (3) 10.2%, (4) 2.6%, (5) 2.6%,(6) 17.9%, (7) 21.8% and (8) 44.9% System II - α a allele 56%, 6 allele 44%. Approximately 80% of females were heterozygous for two different alleles. Hence the Bel I and Taq I polymorphisms can be used to track the defective factor VIII gene for carrier detection and prenatal diagnosis. Furthermore, their frequencies in the Chinese are different from those previously reported in other ethnic groups.
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