Microsatellite alterations in exfoliated cervical epithelia deoxyribonucleic acid as a marker for high-grade dysplasia

Assessment of the frequency of genetic alterations (LOH/MSI) in patients with intraepithelial cervical lesions with HPV infection: a pilot study

In the present study, we analyzed (1) the type of HPV infection and (2) the frequency of loss of heterozygosity and microsatellite imbalance (LOH/MSI) in normal cytology and cervical intraepithelial neoplasia (CIN1-3). The cytological material included: low-grade squamous intraepithelial lesions (CIN1, n = 11), high-grade lesions (CIN2 and CIN3, n = 13), and cytologically normal cells from non-neoplastic cervical samples (n = 8). HPV genotyping was done using RealLine HPV 16/18 kit. We used 20 microsatellite markers from: 1p31.2, 3p14.3, 3p21.3, 3p22.2, 3p24.2, 3p25.3, 7q32.2, 9p21.3, 11p15.5, 12q23.2, and 16q22.1. LOH/MSI was correlated with clinicopathological parameters. The presence of HPV DNA was revealed in 78.13 % samples, including normal cytology. LOH/MSI was the most frequent for: 3p25.3 (39 %), 3p22.2 (20.83 %), 3p24.2 (20 %), and 3p14.3 (16.67 %). It was demonstrated that D3S1234 (FHIT; 3p14.3), D3S1611 (MLH1; 3p22.2), D3S1583 (RARB; 3p24.2), D3S1317 and D3S3611 (VHL; 3p25.3) could differentiate patients with CIN2/CIN3 versus CIN1, showing significantly higher frequency in CIN2/CIN3. LOH/MSI frequency for other than 3p markers was lower, 10-22.2 %. The simultaneous occurrence of LOH/MSI for several markers (OFAL) was higher in CIN2/CIN3. Significant differences in OFAL were found between samples with versus without HPV infection. In HPV-positive patients, significant differences in OFAL were found between normal cytology, CIN1 and CIN2/CIN3. HPV infection influences the increase in LOH/MSI frequency, especially in tumor suppressor gene loci. Several studied microsatellite markers seem to be useful for CIN grading. Hopefully, the obtained results, if confirmed on larger patient cohort, would allow creating a panel of markers supporting clinical diagnosis in patients with HPV infection.

Molecular Basis for Advances in Cervical Screening

Human papillomaviruses (HPVs) cause cervical lesions, which can, in some instances, progress to high-grade neoplasia and cancer. Around half a million cases of cervical cancer occur each year, with most occurring in developing countries where cervical cancer is a major cause of cancer-related death. The reduction in cervical cancer incidence in developed countries is largely attributed to the introduction of cervical screening. Cervical screening currently depends on the identification by cytology of abnormalities in cells taken from the surface of the cervix. The standard Pap test was developed >50 years ago, and despite modifications, still forms the basis of the test currently in use in most routine screening laboratories. Advances in our understanding of the molecular mechanisms that lead to the development of cervical cancer have been slow to impact on screening, despite the relatively high false-negative rates that can be associated with the conventional Pap smear. Improvements in screening strategies fall into a number of categories. Methods that improve cell presentation and attempt to eliminate artefacts/obscuring debris can be combined with image analysis systems in order to enhance diagnostic accuracy. Such approaches still rely on cytological evaluation and do not incorporate advances in our knowledge of how HPV causes cancer. By contrast, markers of virus infection or cell cycle entry, particularly those that offer some degree of prognostic significance, may be able to highlight abnormal cells more reliably than cytology, and could be combined with cytology to improve the detection rate. Our understanding of the molecular biology of HPV infection and the organization of the HPV life-cycle during cancer progression provides a rational basis for marker selection. The general assumption that persistent active infection by high-risk HPV types is the true precursor of cervical cancer provides the rationale for HPV DNA testing in conjunction with enhanced cytology, while the development of RNA-based approaches should allow active infections to be distinguished from those that are latent. The detection in superficial cells of marker combinations at the level of RNA or protein has the potential to predict disease status more precisely than the detection of markers in isolation. There is also a need for better prognostic markers if the predictive value of screening is to be improved. The potential to control infection by vaccination should reduce the incidence of HPV-associated neoplasia in the population, and this may cause a change in the way that screening is carried out. Nevertheless, the lack of a therapeutic vaccine, and the difficulties associated with eliminating infection by multiple high-risk HPV types, means that some form of screening will still be required as a preventive measure for the control of cervical cancer for the foreseeable future.

Translational approaches to improving cervical screening

Screening programmes for cervical cancer using the current test--the Pap smear--have markedly reduced the incidence of the disease. However, an individual Pap test is of limited sensitivity and is difficult and expensive to perform. Increased understanding of the molecular pathogenesis of cervical cancer indicates that new approaches to screening might offer increased accuracy, affordability and the potential for automation. Such approaches exemplify how improved understanding of the biology of neoplasia might be translated into clinical benefit.

Microsatellite alterations in free-circulating serum DNA in patients with ulcerative colitis

BACKGROUND/AIMS

The aim of this study was to find out whether there is free-circulating DNA in the serum of patients with ulcerative colitis and whether it is possible to establish a panel of genetic alterations which might be useful markers for diagnostic purposes, staging, or follow up.

METHODS

A set of 11 microsatellite markers located on different chromosomes were analyzed in a group of 59 patients with ulcerative colitis. Radiolabeled PCR products from serum and white blood cell DNA were analyzed by autoradiography and correlated with the clinical data from these patients.

RESULTS

Seven of 59 patients showed one or more microsatellite alteration(s) in their serum DNA. Six patients had an alteration in one marker, and two patients had changes in 4 markers, respectively. There was no correlation between the frequency of microsatellite alterations and the clinical data.

CONCLUSION

From the panel of 11 microsatellite markers used for these studies, 6 of them seem to be well suited for the detection of ulcerative colitis-associated alterations in free circulating serum DNA. In order to increase the specificity of this assay, it is necessary to increase the number of patients to be analyzed and to use a different set of markers.