ABSTRACT
Oncogenic mutations in proto-oncogenes and tumor suppressor genes represent one of key events in cancerogenesis. In this study, we analysed mutation status in PIK3CA, KRAS and EGFR proto-oncogenes and TP53 tumor suppressor gene in a cohort of twenty-four patients diagnosed with squamous cell carcinoma or adenocarcinoma using the screening method "High Resolution Melting" (HRM). Positive findings were confirmed and identified by Sanger sequencing. Totally, we detected DNA sequence changes in targeted regions in seven patients (7/24, 29.2%). In PIK3CA gene, we found six sequence changes in four patients (4/24, 16.7%) and four of them were confirmed as oncogenic mutations. In KRAS gene, we detected sequence changes in four patients (4/24, 16.7%). Conversely, we identified pathogenic or potentially pathogenic sequence changes neither in EGFR nor TP53 genes. Our results suggest that sequence changes are specific neither for a certain histological subtype, clinical stage nor lymph node involvement and they appear independently on the presence of HPV (human papillomavirus) infection since early clinical stages. We observed the correlation between the presence of DNA sequence changes and hTERC gene amplification, but we did not find a significant relationship between the identified DNA sequence changes and detected copy-number alterations using the technique of array-CGH (array-based comparative genomic hybridization). Regardless our results confirmed an important role of oncogenic mutations in PIK3CA and KRAS genes in the neoplastic transformation process in the cervical carcinoma pathogenesis. Their identification in the early clinical stages should encourage further studies to better understand these mutations and exploit them for more detailed diagnostics.
Subject(s)
Adenocarcinoma/genetics , Carcinoma, Squamous Cell/genetics , Class I Phosphatidylinositol 3-Kinases/genetics , Proto-Oncogene Proteins p21(ras)/genetics , Tumor Suppressor Protein p53/genetics , Uterine Cervical Neoplasms/genetics , Base Sequence , Carcinogenesis/genetics , Cohort Studies , ErbB Receptors/genetics , Female , Genetic Predisposition to Disease/genetics , Humans , Papillomaviridae/isolation & purification , RNA/genetics , Sequence Analysis, DNA , Telomerase/geneticsABSTRACT
UNLABELLED: It is known that cervical cancer develop from precancerous intraepithelial neoplasia (CIN) which is characterized by series of genetic abnormalities. The progression of CIN to cervical carcinoma has been associated especially with the genomic integration of oncogenic human papilloma virus (HPV) and gain of the human telomerase RNA gene hTERC (3q26) and MYC (8q24). In this study, cytology specimens of cervical intraepithelial neoplasia and cervical carcinoma from 74 Czech women were analyzed using the triple-color Cervical FISH Probe Kit designed for identification of HPV infected cells and copy number aberration of the hTERC and MYC genes. HPV-positivity exhibited 70% of patients with premalignant lesions (CIN I - CIN III, carcinoma in situ), chromosomal changes were found in 53.3% of cases - MYC amplification had 33.3% of women with CIN I - CIN III and 50% with carcinoma in situ. Amplification of hTERC was detected in 16.7% of patient with CIN I, in 50% with CIN II, in 58.3% with CIN III and in 66.7% with carcinoma in situ. Based on HPV-positivity and the occurrence of chromosomal aberrations, patients were divided into high-, intermediate- and low-risk group. Among women with cervical carcinomas, HPV infection was detected in 90.1% of specimens and chromosomal aberrations were found in 87.5% of samples. Amplification of MYC gene was detected in 25% and hTERC gene in 62.5% of patients. According to the histopathological grade of tumors, MYC gene amplification occurred more frequently in specimens of spinocellular carcinoma than adenocarcinoma (p=0.029). We found no association between the frequency of cytogenetic lesions and the incidence of lymphangiogenesis or lymph node metastases in cervical carcinoma patients. Simultaneous hTERC and MYC genes amplification was significantly more frequent in samples of cervical carcinomas than in premalignant lesions (p=0.008).In a cohort of 26 patients with cervical carcinoma we used oligo-based GGH+SNP microarray technique for the high resolution mapping of copy number changes of hTERC and MYC genes. We found that recurrent gain of genetic material in chromosome 3q26 area carrying hTERC gene of size 43.6 Mb between 3q25.1-3qter and duplication of 3q were the most common genomic identifications of amplified gene. In MYC locus array-CGH profiling identified duplication of 8q and trisomy 8 as frequent genomic changes.Our work confirmed that in cervical carcinoma gains of hTERC and MYC genes are specific genomic changes associated with developing of malignant phenotype. We also showed that in premalignant stages HPV-FISH assay can be used as an effective diagnostic procedure to identify patients carrying highly risking HPV infection and chromosomal aberrations associated with this malignancy. KEYWORDS: cervical cancer, cervical dysplasia, HPV infection, hTERC amplification, MYC amplification, FISH, array-CGH.
ABSTRACT
BACKGROUND: Chromosomal aberrations play an important role as prognostic factors in chronic lymphocytic leukemia (CLL). These aberrations are mostly detected by fluorescent in situ hybridization (FISH), as chromosomal banding analysis has been scarce due to low proliferative activity of malignant B-lymphocytes in vitro. In 2006, a new method using stimulation with IL-2 and CpG oligonucleotide DSP30 for metaphase generation in CLL was published [1]. The objective of our study was to verify the efficacy of stimulation and to evaluate if the method is suitable for routine diagnostics. PATIENTS AND METHODS: In total, peripheral blood samples of 369 CLL patients were analyzed in parallel by chromosomal banding analysis and by FISH probes for 13q14, 11q22-23, CEP12 and 17p13. RESULTS: Out of 369 patients, 307 (83%) were successfully stimulated for metaphase generation. Chromosomal aberrations were detected in 243 (79%) out of 307 patients evaluated by chromosomal banding analysis. Other aberrations that are not included into standard FISH panel were detected in patients karyotypes, e.g. del(6q), del(14q), t(14;18)(q32;q21), t(11;14)(q13;q32) and t(18;22)(q21;q11). One hundred and three (42%) patients showed complex aberrant karyotype not detected by FISH analysis. CONCLUSION: Stimulation with IL-2 and oligonucleotide DSP30 is an efficient method how to induce proliferation of malignant B-lymphocytes and allows detection of a substantial number of chromosomal aberrations in addition to those detected by standard FISH panel. Using this method in routine diagnostics is helpful particularly in identification of patients with complex aberrant karyotype.