Jaime Matta

Estrogen Receptor Expression Is Associated with DNA Repair Capacity in Breast Cancer.

Estrogen-receptor-positive (ER+) tumors employ complex signaling that engages in crosstalk with multiple pathways through genomic and non-genomic regulation. A greater understanding of these pathways is important for developing improved biomarkers that can better determine treatment choices, risk of recurrence and cancer progression. Deficiencies in DNA repair capacity (DRC) is a hallmark of breast cancer (BC); therefore, in this work we tested whether ER signaling influences DRC. We analyzed the association between ER positivity (% receptor activation) and DRC in 270 BC patients, then further stratified our analysis by HER2 receptor status. Our results show that among HER2 negative, the likelihood of having low DRC values among ER- women is 1.92 (95% CI: 1.03, 3.57) times the likelihood of having low DRC values among ER+ women, even adjusting for different potential confounders (p<0.05); however, a contrary pattern was observed among HER2 positives women. In conclusion, there is an association between DRC levels and ER status, and this association is modified by HER2 receptor status. Adding a DNA repair capacity test to hormone receptor testing may provide new information on defective DNA repair phenotypes, which could better stratify BC patients who have ER+ tumors. ER+/HER2- tumors are heterogeneous, incompletely defined, and clinically challenging to treat; the addition of a DRC test could better characterize and classify these patients as well as help clinicians select optimal therapies, which could improve outcomes and reduce recurrences.

Cytotoxicity and Genotoxicity Assessment of Sandalwood Essential Oil in Human Breast Cell Lines MCF-7 and MCF-10A

Sandalwood essential oil (SEO) is extracted from Santalum trees. Although α-santalol, a main constituent of SEO, has been studied as a chemopreventive agent, the genotoxic activity of the whole oil in human breast cell lines is still unknown. The main objective of this study was to assess the cytotoxic and genotoxic effects of SEO in breast adenocarcinoma (MCF-7) and nontumorigenic breast epithelial (MCF-10A) cells. Proteins associated with SEO genotoxicity were identified using a proteomics approach. Commercially available, high-purity, GC/MS characterized SEO was used to perform the experiments. The main constituents reported in the oil were (Z)-α-santalol (25.34%), (Z)-nuciferol (18.34%), (E)-β-santalol (10.97%), and (E)-nuciferol (10.46%). Upon exposure to SEO (2–8u2009μg/mL) for 24 hours, cell proliferation was determined by the MTT assay. Alkaline and neutral comet assays were used to assess genotoxicity. SEO exposure induced single- and double-strand breaks selectively in the DNA of MCF-7 cells. Quantitative LC/MS-based proteomics allowed identification of candidate proteins involved in this response: Ku70 (p = 1.37E − 2), Ku80 (p = 5.8E − 3), EPHX1 (p = 3.3E − 3), and 14-3-3ζ (p = 4.0E − 4). These results provide the first evidence that SEO is genotoxic and capable of inducing DNA single- and double-strand breaks in MCF-7 cells.

Variability in DNA Repair Capacity Levels among Molecular Breast Cancer Subtypes: Triple Negative Breast Cancer Shows Lowest Repair

Breast cancer (BC) is a heterogeneous disease which many studies have classified in at least four molecular subtypes: Luminal A, Luminal B, HER2-Enriched, and Basal-like (including triple-negative breast cancer, TNBC). These subtypes provide information to stratify patients for better prognostic predictions and treatment selection. Individuals vary in their sensitivities to carcinogens due to differences in their DNA repair capacity (DRC) levels. Although our previous case-control study established low DRC (in terms of NER pathway) as a BC risk factor, we aim to study this effect among the molecular subtypes. Therefore, the objectives of this study include investigating whether DRC varies among molecular subtypes and testing any association regarding DRC. This study comprised 267 recently diagnosed women with BC (cases) and 682 without BC (controls). Our results show a substantial variability in DRC among the molecular subtypes, with TNBC cases (n = 47) having the lowest DRC (p-value < 0.05). Almost 80 percent of BC cases had a DRC below the median (4.3%). Low DRC was strongly associated with the TNBC subtype (OR 7.2; 95% CI 3.3, 15.7). In conclusion, our study provides the first report on the variability among the molecular subtypes and provides a hypothesis based on DRC levels for the poor prognosis of TNBC.

High DRC Levels Are Associated with Let-7b Overexpression in Women with Breast Cancer

Nucleotide Excision Repair (NER) is a critical pathway involved in breast cancer (BC). We have previously published that a low DNA repair capacity (DRC) is associated with a higher risk of BC in Puerto Rican women. Let-7b belongs to a miRNA family with tumor suppressor activity that targets oncogenes. We isolated miRNAs from plasma of 153 Puerto Rican women with and without BC. DRC was measured in lymphocytes by means of a host cell reactivation assay. These women were divided into four groups according to their DRC level: High (>3.8%) and low (<3.8%). The four groups consisted of BC patients with high (n = 35) and low (n = 43) DRC and controls with high (n = 39) and low (n = 36) DRC. Epidemiologic data were collected at initial BC diagnosis and almost five years after diagnosis. A significant difference in Let-7b expression was found in BC patients with high DRC versus the remaining groups (p < 0.001). Thus, our data reveal a possible role of Let-7b on DRC during breast carcinogenesis. Our study is innovative because it provides the first evidence that Let-7b may play role in DRC regulation (through the NER repair pathway) in BC.

Abstract 3286: Correlation between vitamin D levels and DNA repair capacity in breast cancer patients stratified by molecular subtypes

Vitamin D exists as vitamin D2 and D3, which are metabolized to 25-hydroxyvitamin D [25(OH)D], the major circulating vitamin D metabolite. Besides its physiological functions, vitamin D levels have also been studied as a risk factor for several hormonal cancers including breast cancer (BC). Worldwide, BC accounts for nearly a quarter of all cancers in women. Nutritional studies report that vitamin D intake is associated with a lower BC risk. Several discrepancies exist regarding the role of serum vitamin D in BC risk. While some studies report BC risk reduction by vitamin D only in premenopausal, others propose that it only occurs in postmenopausal women. BC tumors may (+) or may not (-) have three hormonal receptors: estrogen (ER), progesterone (PR), and HER2. Based on their status, four principal molecular BC subtypes have been identified: luminal A (ER+/−, PR+/−, HER2-), luminal B (ER+/−, PR+/−, HER2+), HER2+ (ER−, PR−, HER2+), and triple negative (TN) (ER−, PR−, HER2−). If BC is analyzed in terms of molecular subtypes, low vitamin D levels have been associated with aggressive phenotypes and worse prognosis. Vitamin D also influences estrogen synthesis. Since we have previously shown that a low DNA repair capacity (DRC), measured through the nucleotide excision repair pathway, is a risk factor for BC and vitamin D has also been found to affect DNA repair, the focus of this study is to examine the role of plasma vitamin D levels and DRC in BC. The main aim is to elucidate whether there is an association between vitamin D and DRC levels among the four molecular BC subtypes. We hypothesize that a negative correlation between 25(OH)D and DRC levels will be observed among these subtypes. As an initial effort, 47 BC cases and 20 controls without BC were selected from our large BC cohort. DRC was measured in lymphocytes of untreated women using the host cell reactivation assay. Pathology reports were examined to divide BC cases according to their molecular BC subtype: luminal A (n=13), luminal B (n=11), HER2+ (n=10), and TN (n=13). Plasma 25(OH)D levels were measured using the UniCel DxC System at a CLIA-certified lab. Our results show a negative correlation between 25(OH)D and DRC levels (p=0.04). Statistically significant differences were found for vitamin D levels among the different groups (p=0.0019, ANOVA). Moreover, higher 25(OH)D levels (47.97±2.4 ng/mL) were found in ER- BC cases (p=0.03, t-test). When comparing vitamin D levels in BC subtypes, a significant difference was found in HER2+ and TN groups when compared with the control group (p Citation Format: Carmen Ortiz, Jarline Encarnacion, Ralphdy Vergne, Wanda Vargas, Jaime Matta. Correlation between vitamin D levels and DNA repair capacity in breast cancer patients stratified by molecular subtypes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3286. doi:10.1158/1538-7445.AM2017-3286

Abstract 1899: Let-7b overexpression is associated with higher nucleotide excision repair pathway in women with breast cancer

Nucleotide Excision Repair (NER) is a critical pathway involved in breast cancer (BC). We have previously published that a low DNA repair capacity (DRC) is associated with a higher risk of BC in Puerto Rican women. In recent years we have focused our investigations on microRNAs (miRNAs) that are differentially associated with a low and a high DRC in women with BC and controls. A discovery experiment with 29 BC cases and 27 controls produced 12 candidate miRNAs associated with DRC including let-7b. The main objective of this study was to elucidate if there is a correlation between let-7b expression and specific DRC levels. Let-7b belongs to a miRNA family with tumor suppressor activity that targets oncogenic genes such as Ras, Myc, and HmgA2. DRC was measured in lymphocytes by means of a host cell reactivation assay with a luciferase reporter gene. We isolated miRNAs from plasma of 145 Puerto Rican women with and without BC (recently diagnosed, untreated cases and controls) using the miRNeasy kit (Qiagen). These women were divided into four groups according to their DRC level: high (>3.8%) and low ( Citation Format: Jarline Encarnacion, Carmen Ortiz, Ralphdy Vergne, Wanda Vargas, Jaime L. Matta. Let-7b overexpression is associated with higher nucleotide excision repair pathway in women with breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1899.

Abstract 3851: Low educational level is associated with a reduced DNA repair capacity and higher risk of breast cancer

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PAnnBACKGROUND: Breast Cancer (BC) is the leading cause of cancer deaths among females in Puerto Rico. Educational level is well established as a modifier of cancer risk. We have undertaken a large population study and have shown that a low DNA Repair Capacity (DRC) is an important risk factor for BC. It is well established that DRC is regulated by genetic, epigenetic and environmental factors. We have investigated the relationship between educational level and DRC.nnThe purpose of this study was to evaluate the role of educational level as a modifier of the association between DRC and risk of BC in Puerto Rican women. METHODS: A total of 488 women with histopathologically confirmed BC and 607 controls were selected for the analysis. DRC was measured in lymphocytes using a host cell reactivation assay. Pathology reports were used to obtain tumor size. DRC levels were divided into low, medium and high using tertiles. Multiple logistic regression was used to assess the association among educational level and BC risk factors adjusted by DRC. For the analysis of tumor size and DRC, educational levels were divided into primary education, high school, and associate or more. Analysis of variance was performed using the Kruskal-Wallis test. RESULTS: Women with lower educational level (elementary education) had significantly higher risk of BC (OR: 5.9, 95%CI: 2.3, 14.9) followed by high school (OR: 1.4, 95%CI: 1.1, 2.1) and associate degree (OR: 1.4, 95%CI: 0.9, 2.2) using bachelors degree as a referent. Women with low education had 8.9 times the odds of having low DRC (95%CI: 5.2, 15.2), while women with high educational level had 11.7 times the odds for a low DRC (95%CI: 7.7, 17.7). The association and tumor size (cm) and educational level showed that as educational level increased, women had smaller tumor sizes (Kruskal-Wallis test p = 0.031). CONCLUSIONS: This study showed that women with the lowest levels of education, in general, had a lower DRC and significantly higher risk of BC and of having larger breast tumors when compared to controls. This study provides new insights as to how educational level can influence BC risk. This association is controversial because some studies attribute a high educational level to high risk of BC while others present the opposite. Because our study uses a biological variable (DNA repair) to measure risk, it reduces ambiguity in terms of the criterion to estimate risk. Those with the highest levels of education had smaller tumors; therefore consequently better chances for early treatment and increased chances of survival. Because education is a modifiable lifestyle factor, this study provides data that can be utilized to identify women with a higher risk of developing BC in order to design more effective BC screening, and diagnosing BC an earlier stage. Supported by grants from the NCI Diversity Training Branch through the NIH-MBRS Program grants S06 GM008239-20, 9SC1CA182846-04 to PSMHS through JM and MBRS-RISE GM082406 through CO.nnCitation Format: Luisa Morales, Manuel Bayona, Carmen Ortiz, Damian Adams, Carolina Alvarez-Garriga, Jaime L. Matta. Low educational level is associated with a reduced DNA repair capacity and higher risk of breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3851. doi:10.1158/1538-7445.AM2015-3851

Abstract P5-06-05: miRNAs associated with DNA repair capacity in Puerto Rican women with breast cancer

BACKGROUND: MicroRNAs (miRNA) are short non-protein-coding RNAs that regulate gene expression at the post-transcriptional level via binding to 3′-untranslated regions of protein-coding transcripts. Some miRNAs have been used as diagnostic, prognostic and therapeutic markers of breast cancer (BC). It is well established that dysregulation of DNA repair capacity (DRC) is an important risk factor of BC. However, there is little published information as to what specific miRNAs are associated with DRC in women with BC. OBJECTIVE : The main objective of this study was to identify candidate miRNAs associated with dysregulation of DRC in women with BC. METHODS: Plasma samples from 30 BC cases and 30 controls selected based on their DRC levels (low, high) using a proprietary algorithm. Samples were analyzed for miRNA expression utilizing protocols from Applied Biosystems (Life Technologies). The miRNA expression profiling was performed utilizing the RT-PCR TaqMan Array Human MicroRNA A Cards v 2.0 (Applied Biosystems) containing 383 miRNA probes. Single-stranded cDNA was synthesized from 200 ng of total RNA in 8 Multiplex RT primer pool reactions containing stem-looped RT primers that were specific to mature miRNAs. U6 snRNA-001973 was selected for normalization based on our own experimental validations. To quantify the association of the miRNA expression the fold change () was estimated for every detector with the p-values calculated using the t-test. RESULTS: Candidate miRNAs that showed a statistically significant expression were: miR-146, miR-34a, miR-221, Let-7b, miR-193b, miR-132, miR-192, miR-21, miR-197, miR-24, miR-26b, miR-29c were identified based on a false discovery rate of 4%. The results showed that twelve miRNAs differentially expressed in patients with BC. Candidate miRNAs have been reported associated with the expression of twenty seven DNA repair genes. Two of these genes are part of the NER pathway which has been identified by previous studies as important in BC. CONCLUSION: Our preliminary data suggests that differential expression of specific miRNAs might be associated with dysregulation of DRC in BC. The molecular mechanisms by which miRNAs regulate DNA repair genes remain to be elucidated. However, our results lend further promise to the concept of miRNAs as a tool to study the regulation of DRC. We see potentialfuture applications in prognosis and therapy of women with BC. Supported by grants S06 GM008239-20 and 1SCA157250 from the NCI Center to Reduce Health Disparities and NIH-MBRS Program (NIGMS) and NIH-NIGMS #GM082406 (CO). Citation Format: Jaime Matta, Clara Isaza, Carmen Ortiz, Erick Suarez, Luisa Morales. miRNAs associated with DNA repair capacity in Puerto Rican women with breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-06-05.