Decreased Expression of BRCA2 Accelerates Sporadic Breast Cancer Progression

Identification of New Molecular Biomarkers in Ovarian Cancer Using the Gene Expression Profile

Ovarian cancer is a common cause of death among women worldwide. The current diagnostic and prognostic procedures available for the treatment of ovarian cancer are either not specific or are very expensive. Gene expression profiling has proved to be a very effective tool in the exploration of new molecular markers in patients with ovarian cancer, although the link between such markers and patient survival and clinical outcomes is still elusive. We are looking for genes that may function in the development and progression of ovarian cancer. The aim of our study was to evaluate the expression of selected suppressor genes (ATM, BRCA1, BRCA2), proto-oncogenes (KRAS, c-JUN, c-FOS), pro-apoptotic genes (NOXA, PUMA), genes related to chromatin remodeling (MEN1), and genes related to carcinogenesis (NOD2, CHEK2, EGFR). Tissue samples from 30 normal ovaries and 60 ovarian carcinoma tumors were provided for analysis of the gene and protein expression. Gene expression analysis was performed using the real-time PCR method. The protein concentrations from tissue homogenates were determined using the ELISA technique according to the manufacturers’ protocols. An increase in the expression level of mRNA and protein in women with ovarian cancer was observed for KRAS, c-FOS, PUMA, and EGFR. No significant changes in the transcriptional levels we observed for BRCA1, BRCA2, NOD2, or CHEK2. In conclusion, we suggest that KRAS, NOXA, PUMA, c-FOS, and c-JUN may be associated with poor prognosis in ovarian cancer.

An information-theoretical analysis of gene nucleotide sequence structuredness for a selection of aging and cancer-related genes

We provide an algorithm for the construction and analysis of autocorrelation (information) functions of gene nucleotide sequences. As a measure of correlation between discrete random variables, we use normalized mutual information. The information functions are indicative of the degree of structuredness of gene sequences. We construct the information functions for selected gene sequences. We find a significant difference between information functions of genes of different types. We hypothesize that the features of information functions of gene nucleotide sequences are related to phenotypes of these genes.

BRCA1 and BRCA2 mRNA-expression prove to be of clinical impact in ovarian cancer

BACKGROUND

Mutations in BRCA1 and BRCA2 are associated with better survival in ovarian cancer (OC) patients due to a better response to platinum-based chemotherapy. However, the impact of the BRCA1/2 mRNA-expression is not well characterized in OC.

PATIENTS AND METHODS

We investigated BRCA1/2 mRNA-expression in 12 non-neoplastic fallopian tubes and 201 epithelial OCs in relation to their clinical characteristics.

RESULTS

We found higher BRCA1/2 mRNA-expression in OCs compared to controls (P = 0.011, P < 0.001, respectively). BRCA1 mutated OCs exhibited lower BRCA1 (P = 0.014) but higher BRCA2 mRNA-expression (P = 0.001). Low BRCA1-expression was associated with favorable overall survival (OS) (P = 0.012) and low BRCA2-expression with better progression-free survival (PFS) and OS (P = 0.004, P = 0.001, respectively). A subgroup-analysis showed that this effect was confined only to the BRCA1-wildtype cancers. Cox-regression confirmed the prognostic significance of BRCA1-expression for OS (P = 0.028). Independency of the prognostic value of BRCA2-expression for PFS (P = 0.045) and OS (P = 0.015) was restricted to high-grade serous OCs. Fully platinum-sensitivity was characterized by lower BRCA1/2 mRNA-expression in BRCA1-wildtype cancers in comparison to platinum-refractory OC.

CONCLUSION

Our findings may reflect higher platinum-sensitivity due to reduced capacity of DNA damage repair in tissues with low BRCA1/2-expression. In this context, especially in BRCA-wildtype cancers both parameters could also be potential predictors for PARP-sensitivity.