The detection of circulating tumor cells expressing E6/E7 HR-HPV oncogenes in peripheral blood in cervical cancer patients after radical hysterectomy.

The aim of this study was to establish the sensitive, specific and clinically acceptable method for detection of tumor cells (TCs) circulating in peripheral blood (PB) of cervical cancer patients without the clinically detectable risk of disease progression. The 7.5 ml of PB of healthy donor was spiked with 5 to 100 cells from SiHa or HeLa cell lines. The spiked tumor cells were collected without gradient centrifugation, by standard gradient centrifugation or by modified gradient centrifugation combined with immunomagnetic separation using EpCAM antibody with affinity for epithelial cell adhesion molecule. The number of collected TCs was determined by EpCAM-FITC-staining and their viability was detected by nested RT-PCR amplifying E6/E7 HR-HPV 16 or HR-HPV 18 oncogenes. For the technical validation of this approach the TCs separation and RT-PCRs were repeated several times. The recovery of viable TCs was reproducibly higher using modified gradient centrifugation combined with immunomagnetic separation in comparison with standard approach. The recovery of TCs in low number of spiked TCs (range from 5 - 20 TCs in 7.5 ml of PB) using modified gradient centrifugation was not reproducible. The recovery of TCs in higher number of spiked TCs (25 TCs and more in 7.5 ml of PB) was reproducible with average recovery about 50 %. The sensitivity of nested RT-PCR amplifying E6/E7 oncogenes was decisively influenced by the number of recovered TCs and the amount of cDNA introduced to RT-PCR, as well. Using this approach we were allowed to detect circulating TCs (CTCs) in cervical cancer patients without metastases, thus this procedure might become a tool to early estimation of disease progression. According to our knowledge, this is the first report describing the use of EpCAM antibody for CTCs detection in cervical cancer patients.

Genetic analysis of KRAS mutation status in metastatic colorectal cancer patients.

Colorectal carcinoma (CRC) represents a serious problem worldwide: in the Slovak republic are diagnosed about 2600 new CRC cases annually and its incidence is increasing. Colorectal cancer patients may succumb to the disease because of local recurrence or local formation of metastasis. Therefore, it is necessary to modulate therapeutic algorithm with new methods, leading to early diagnostic of CRC or changing the existing therapeutic procedures. Recent progresses have been made in understanding of EGFR pathway involved in CRC carcinogenesis, especially the role of Ras protein. Mutations in KRAS oncogene are frequently found in human cancers, particularly colorectal, pancreatic, billiary tract and lung tumors. The presence of the KRAS mutations in metastatic colorectal cancer patients correlates with lack of response to the certain epidemal growth factor receptor (EGFR) inhibitor therapies, such as Panitumumab and Cetuximab. Consequently, screening for KRAS mutations status may be used as a prognostic marker, because the CRC patients with KRAS positive tumors have a worse prognosis. The aim of our study was to establish the methods for rapid and sensitive detection of KRAS mutation status in formalin fixed paraffin embedded (FFPE) tissues DNA. We applied Real Time PCR analysis (TheraScreen KRAS Mutation Test Kit) and sequencing analysis (optimised for the analysis of FFPE tissues) to detect somatic mutations in codon 12 and 13 of KRAS gene. Both methods were used concurrently in the panel of DNA isolated from 25 colorectal FFPE tissues tumor. The positive or negative results from all 25 samples were identified by both methods independently. The KRAS mutations were presented in 8 of 25 patients (32%). Our results demonstrate that the Real Time PCR analysis can be used for detection of somatic KRAS mutations in FFPE clinical samples. However, we also recognize that the sequencing analysis of approximately 200bp amplicons may be used for mutations status screening, but with care of method sensitivity.

The spectrum and incidence of BRCA1 pathogenic mutations in Slovak breast/ovarian cancer families.

Pathogenic germline mutations in BRCA1 and BRCA2 account for the majority of hereditary breast/ovarian cancer cases. The analysis of BRCA1 gene was carried out in 156 breast/ovarian cancer families: 82 families with strong family history and 59 families with medium family history. Generally, 31 families and 71 cases with BRCA1 pathologic mutations (14 different types) were identified in this study by combination of SSCP and direct sequencing techniques. Using approved systematic nomenclature numbering, c.5266dupC (8 families, 21 cases), c.181T>G (5 families, 11 cases), c.68_69delAG (3 families, 5 samples) and c.843_846del4 (3 families, 4 samples) were the most frequently found mutations in BRCA1 gene. Altogether these 4 mutations accounted for 61.3% of all detected pathogenic mutations in BRCA1. One novel mutation c.1166delG was detected in one family (4 cases). Frame-shift mutations were found in 21 families (46 cases), nonsense mutations in 4 families (8 cases) and missense mutations in 6 families (17 cases). Even though the 4 most frequent mutations account for 61.3% of all detected pathogenic mutations, screening of the whole BRCA1 coding region is necessary, due to the large scale of low frequency disease causing mutations in breast/ovarian cancer families in Slovakia.

New approach to human high-risk papillomavirus (HR-HPV) genotyping.

Human high-risk papillomaviruses (HR-HPVs) are involved in the induction of invasive cervical cancer. The aim of this study was to introduce a simple, semi-automated and reproducible approach suitable for HR-HPV detection in clinical practice. The procedure is based on DNA isolation, nested polymerase chain reaction, single strand conformational polymorphism and evaluation of HR-HPV genotypes with Gel-Pro software. The clinical performance of the new approach was assessed in two different patient materials: 1) cervical smears with cytological classification Pap2-3 or Pap3 lacking nuclear atypia (anisonucleosis and polychromasia) or koilocytotic atypia and without any previous therapy 2) formalin-fixed, paraffin-embedded cervical carcinoma and lymph node sections. Using the new approach we detected HR-HPV DNA in 64% patient samples cytologically classified as Pap2-3 or Pap3 respectively and in 80% formalin-fixed, paraffin-embedded lymph node sections histologically classified as lymph nodes without carcinoma cell infiltration. The combination of methods described in this study results in increased sensitivity of HR-HPV identification allowing detection of HPV DNA in a very small amount of target DNA so that it can be widely used in distinguishing the pre- malignant lesions and in determination of invading carcinoma cells to lymph nodes in patients with advanced cervical cancer. The new approach is useful in unambiguous HR-HPV genotyping even in double-HPV infection.

Role of DNA polymerase II in the tolerance of thymine dimers remaining unexcised in UV-irradiated Escherichia coli exposed to pre-UV nutritional stress.

Nutritional stress applied prior to UV-irradiation to E. coli 15 555-7 reduced thymine dimer excision and inhibited post-UV incorporation of thymidine in polB(+) as well as in polB(-) cells. However, the pre-UV-stressed polB(+) cells were significantly more UV-resistant and after UV synthesized larger DNA molecules than the pre-UV-stressed polB(-) cells. The data suggest that DNA polymerase II is involved in the tolerance of unremoved thymine dimers.

Escherichia coli strain with a deletion of the chromosomal ampC gene marked with TcR, suitable for production of penicillin G acylase.

Escherichia coli strain which contains a marker of tetracycline resistance gene (TcR) placed by P1 transduction beside the chromosomal deletion of ampC gene (delta ampC) coding for beta-lactamase was constructed. Such introduction of TcR marker permits a fast and simple selection for the transfer of delta ampC by P1 transduction into industrial E. coli strains. This approach was used for constructing an E. coli strain suitable for penicillin acylase production.