Molecular features of premenopausal breast cancers in Latin American women: Pilot results from the PRECAMA study.

BACKGROUND: In Latin America (LA), there is a high incidence rate of breast cancer (BC) in premenopausal women, and the genomic features of these BC remain unknown. Here, we aim to characterize the molecular features of BC in young LA women within the framework of the PRECAMA study, a multicenter population-based case-control study of BC in premenopausal women. METHODS: Pathological tumor tissues were collected from incident cases from four LA countries. Immunohistochemistry (IHC) was performed centrally for ER, PR, HER2, Ki67, EGFR, CK5/6, and p53 protein markers. Targeted deep sequencing was done on genomic DNA extracted from formalin-fixed, paraffin-embedded tumor tissues and their paired blood samples to screen for somatic mutations in eight genes frequently mutated in BC. A subset of samples was analyzed by exome sequencing to identify somatic mutational signatures. RESULTS: The majority of cases were positive for ER or PR (168/233; 72%), and 21% were triple-negative (TN), mainly of basal type. Most tumors were positive for Ki67 (189/233; 81%). In 126 sequenced cases, TP53 and PIK3CA were the most frequently mutated genes (32.5% and 21.4%, respectively), followed by AKT1 (9.5%). TP53 mutations were more frequent in HER2-enriched and TN IHC subtypes, whereas PIK3CA/AKT1 mutations were more frequent in ER-positive tumors, as expected. Interestingly, a higher proportion of G:C>T:A mutations was observed in TP53 in PRECAMA cases compared with TCGA and METABRIC BC series (27% vs 14%). Exome-wide mutational patterns in 10 TN cases revealed alterations in signal transduction pathways and major contributions of mutational signatures caused by altered DNA repair pathways. CONCLUSIONS: These pilot results on PRECAMA tumors give a preview of the molecular features of premenopausal BC in LA. Although the overall mutation burden was as expected from data in other populations, mutational patterns observed in TP53 and exome-wide suggested possible differences in mutagenic processes giving rise to these tumors compared with other populations. Further -omics analyses of a larger number of cases in the near future will enable the investigation of relationships between these molecular features and risk factors.

Ribosomal S6 kinase 4 (RSK4) expression in ovarian tumors and its regulation by antineoplastic drugs in ovarian cancer cell lines.

Survival rate in ovarian cancer depends on the stage of the disease. RSK4, which has been considered as a tumor suppressor factor, controls cells invasion due to its antiinvasive and antimetastatic properties. Modulation of RSK4 expression could be an important event to increase the survival rate in ovarian cancer patients. Thus, the goal of the present study was to establish the differences in RSK4 expression among normal, benign and malignant ovarian tissues and to determine whether antineoplastic drugs regulate its expression in SKOV3 and TOV-112D cells. RSK4 levels in 30 malignant ovarian tumors, 64 benign tumors and 36 normal ovary tissues were determined by reverse transcription polymerase chain reaction and Western blot. Modulation of RSK4 expression by two antineoplastic drugs (cisplatin and vorinostat) was also studied in the SKOV3 and TOV-112D ovarian cancer cell lines using the same techniques. RSK4 mRNA and protein levels were decreased in malignant ovarian tumors as compared to benign tumors and normal tissue. These low-RSK4 levels were significantly associated with advanced stages of ovarian cancer. RSK4 expression was increased after incubation of SKOV3 and TOV-112D cell lines with cisplatin and vorinostat for 24 h. The combination of these antineoplastic drugs did not produce a synergistic or additive effect. These results suggest that RSK4 is expressed at low levels in malignant ovarian tumors, which correlates with advanced stages of the disease. Additionally, RSK4 expression is regulated by cisplatin and vorinostat in two ovarian cancer cell lines.

Matrix metalloproteinase-8 promoter gene polymorphisms in Mexican women with ovarian cancer.

Increased levels of matrix metalloproteinase-8 (MMP-8) have been associated with tumor grade and stage in ovarian cancer. Also, it has been reported that higher concentrations of this enzyme in fluid from malignant ovarian cysts compared with benign ovarian cysts. However, no genetic analysis has been conducted yet to assess the contribution of MMP-8 polymorphisms in ovarian cancer. Thus, this study was performed to investigate the frequencies of MMP-8 genotypes in Mexican women with ovarian cancer. MMP-8 promoter genotypes were examined in 35 malignant ovarian tumors, 51 benign tumors, and 37 normal ovary tissues. Two single nucleotide polymorphisms were selected and characterized using polymerase chain reaction-restriction fragment length polymorphism analysis. The chi-square test was used to calculate statistical significance. Haplotype analysis was performed using the SNPstats web tool. Of the two polymorphisms, only the MMP-8 -799 T/T genotype was significantly associated with an increased risk of ovarian cancer (OR 3.78, 95 % CI 1.18-12.13). The Kaplan-Meier analysis for this polymorphism showed that patients with the T/T genetic variant had a tendency toward significant worse overall survival compared with patients with the C/C + C/T genotypes. Haplotype analysis revealed no significant differences in haplotype distribution between benign ovarian tumors, malignant ovarian cancer, and controls. This study suggests that MMP-8 promoter gene polymorphism -799 T/T is significantly associated with an increased risk of ovarian cancer in Mexican women.