Functional germline variants in driver genes of breast cancer

Association of Germline Variation in Driver Genes with Breast Cancer Risk in Chilean Population

Cancer is a genomic disease, with driver mutations contributing to tumorigenesis. These potentially heritable variants influence risk and underlie familial breast cancer (BC). This study evaluated associations between BC risk and 13 SNPs in driver genes MAP3K1, SF3B1, SMAD4, ARID2, ATR, KMT2C, MAP3K13, NCOR1, and TBX3, in BRCA1/2-negative Chilean families. SNPs were genotyped using TaqMan Assay in 492 cases and 1285 controls. There were no associations between rs75704921:C>T (ARID2); rs2229032:A>C (ATR); rs3735156:C>G (KMT2C); rs2276738:G>C, rs2293906:C>T, rs4075943T:>A, rs13091808:C>T (MAP3K13); rs178831:G>A (NCOR1); or rs3759173:C>A (TBX3) and risk. The MAP3K1 rs832583 A allele (C/A+A/A) showed a protective effect in families with moderate BC history (OR = 0.7 [95% CI 0.5-0.9] p = 0.01). SF3B1 rs16865677-T (G/T+T/T) increased risk in sporadic early-onset BC (OR = 1.4 [95% CI 1.0-2.0] p = 0.01). SMAD4 rs3819122-C (A/C+C/C) increased risk in cases with moderate family history (OR = 2.0 [95% CI 1.3-2.9] p ≤ 0.0001) and sporadic cases diagnosed ≤50 years (OR = 1.6 [95% CI 1.1-2.2] p = 0.006). SMAD4 rs12456284:A>G increased BC risk in G-allele carriers (A/G + G/G) in cases with ≥2 BC/OC cases and early-onset cases (OR = 1.2 [95% CI 1.0-1.6] p = 0.04 and OR = 1.4 [95% CI 1.0-1.9] p = 0.03, respectively). Our study suggests that specific germline variants in driver genes MAP3K1, SF3B1, and SMAD4 contribute to BC risk in Chilean population.

Tumor-Associated and Systemic Autoimmunity in Pre-Clinical Breast Cancer among Post-Menopausal Women

Autoantibodies to tumor-associated antigens (anti-TAA) are potential biomarkers for breast cancer, but their relationship systemic autoimmunity as ascertained though antinuclear antibodies (ANA) is unknown and warrants consideration given the common occurrence of autoimmunity and autoimmune diseases among women. The relationship between anti-TAAs and ANA among women who were later diagnosed with breast cancer and others who remained cancer free in the Women's Health Initiative cohort. The study sample included 145 post-menopausal women with baseline ANA data. A total of 37 ANA-positive women who developed breast cancer (i.e., cases; mean time to diagnosis 6.8 years [SE 3.9]) were matched to a random sample of 36 ANA-negative cases by age and time to diagnosis. An age-matched control sample was selected including 35 ANA-positive and 37 ANA-negative women who did not develop breast cancer (i.e., controls; follow-up time ~13 years [SE 3]). Baseline sera were assessed for Immunoglobulin G (IgG) antibodies, measured by custom microarray for 171 breast and other cancer-associated TAA. We used linear regression to estimate cross-sectional associations of ANA with log-transformed anti-TAA among cases and controls. Most anti-TAA did not vary by ANA status. Two anti-TAA were elevated in ANA-positive compared to ANA-negative cases: anti-PGM3 (p = 0.004) and anti-TTN (p = 0.005, especially in cases up to 7 years before diagnosis, p = 0.002). Anti-TAA antibodies were not generally related to ANA, a common marker of systemic autoimmunity. Associations of ANA with particular antigens inducing autoimmunity prior to breast cancer warrant further investigation.

Co-delivery of paclitaxel (PTX) and docosahexaenoic acid (DHA) by targeting lipid nanoemulsions for cancer therapy

Breast cancer is one of the most common types of cancer in female patients with high morbidity and mortality. Multi-drug chemotherapy has significant advantages in the treatment of malignant tumors, especially in reducing drug toxicity, increasing drug sensitivity and reducing drug resistance. The objective of this research is to fabricate lipid nanoemulsions (LNs) for the co-delivery of PTX and docosahexaenoic acid (DHA) with folic acid (FA) decorating (PTX/DHA-FA-LNs), and investigate the anti-tumor activity of the PTX/DHA-FA-LNs against breast cancer both in vitro and in vivo. PTX/DHA-FA-LNs showed a steady release of PTX and DHA from the drug delivery system (DDS) without any burst effect. Furthermore, the PTX/DHA-FA-LNs exhibited a dose-dependent cytotoxicity and a higher rate of apoptosis as compared with the other groups in MCF-7 cells. The cellular uptake study revealed that this LNs were more readily uptaken by MCF-7 cells and M2 macrophages in vitro. Additionally, the targeted effect of PTX/DHA-FA-LNs was aided by FA receptor-mediated endocytosis, and its cytotoxicity was proportional to the cellular uptake efficiency. The anti-tumor efficiency results showed that PTX/DHA-FA-LNs significant inhibited tumor volume growth, prolonged survival time, and reduced toxicity when compared with the other groups. These results indicated that DHA increases the sensitivity of tumor cells and tumor-associated macrophages (ATM2) to PTX, and synergistic effects of folate modification in breast cancer treatment, thus PTX/DHA-FA-LNs may be a promising nanocarrier for breast cancer treatment.

Heritable genomic diversity in breast cancer driver genes and associations with risk in a Chilean population

BACKGROUND

Driver mutations are the genetic components responsible for tumor initiation and progression. These variants, which may be inherited, influence cancer risk and therefore underlie many familial cancers. The present study examines the potential association between SNPs in driver genes SF3B1 (rs4685), TBX3 (rs12366395, rs8853, and rs1061651) and MAP3K1 (rs72758040) and BC in BRCA1/2-negative Chilean families.

METHODS

The SNPs were genotyped in 486 BC cases and 1258 controls by TaqMan Assay.

RESULTS

Our data do not support an association between rs4685:C > T, rs8853:T > C, or rs1061651:T > C and BC risk. However, the rs12366395-G allele (A/G + G/G) was associated with risk in families with a strong history of BC (OR = 1.2 [95% CI 1.0-1.6] p = 0.02 and OR = 1.5 [95% CI 1.0-2.2] p = 0.02, respectively). Moreover, rs72758040-C was associated with increased risk in cases with a moderate-to-strong family history of BC (OR = 1.3 [95% CI 1.0-1.7] p = 0.02 and OR = 1.3 [95% CI 1.0-1.8] p = 0.03 respectively). Finally, risk was significantly higher in homozygous C/C cases from families with a moderate-to-strong BC history (OR = 1.8 [95% CI 1.0-3.1] p = 0.03 and OR = 1.9 [95% CI 1.1-3.4] p = 0.01, respectively). We also evaluated the combined impact of rs12366395-G and rs72758040-C. Familial BC risk increased in a dose-dependent manner with risk allele count, reflecting an additive effect (p-trend = 0.0002).

CONCLUSIONS

Our study suggests that germline variants in driver genes TBX3 (rs12366395) and MAP3K1 (rs72758040) may influence BC risk in BRCA1/2-negative Chilean families. Moreover, the presence of rs12366395-G and rs72758040-C could increase BC risk in a Chilean population.

A versatile transposon-based technology to generate loss- and gain-of-function phenotypes in the mouse liver

BACKGROUND

Understanding the contribution of gene function in distinct organ systems to the pathogenesis of human diseases in biomedical research requires modifying gene expression through the generation of gain- and loss-of-function phenotypes in model organisms, for instance, the mouse. However, methods to modify both germline and somatic genomes have important limitations that prevent easy, strong, and stable expression of transgenes. For instance, while the liver is remarkably easy to target, nucleic acids introduced to modify the genome of hepatocytes are rapidly lost, or the transgene expression they mediate becomes inhibited due to the action of effector pathways for the elimination of exogenous DNA. Novel methods are required to overcome these challenges, and here we develop a somatic gene delivery technology enabling long-lasting high-level transgene expression in the entire hepatocyte population of mice.

RESULTS

We exploit the fumarylacetoacetate hydrolase (Fah) gene correction-induced regeneration in Fah-deficient livers, to demonstrate that such approach stabilizes luciferase expression more than 5000-fold above the level detected in WT animals, following plasmid DNA introduction complemented by transposon-mediated chromosomal gene transfer. Building on this advancement, we created a versatile technology platform for performing gene function analysis in vivo in the mouse liver. Our technology allows the tag-free expression of proteins of interest and silencing of any arbitrary gene in the mouse genome. This was achieved by applying the HADHA/B endogenous bidirectional promoter capable of driving well-balanced bidirectional expression and by optimizing in vivo intronic artificial microRNA-based gene silencing. We demonstrated the particular usefulness of the technology in cancer research by creating a p53-silenced and hRas G12V-overexpressing tumor model.

CONCLUSIONS

We developed a versatile technology platform for in vivo somatic genome editing in the mouse liver, which meets multiple requirements for long-lasting high-level transgene expression. We believe that this technology will contribute to the development of a more accurate new generation of tools for gene function analysis in mice.

Current Testing Guidelines: A Retrospective Analysis of a Community-Based Hereditary Cancer Program

It is estimated that 5% to 10% of all cancers are related to a hereditary cancer syndrome. However, specific cancers, such as pancreatic and ovarian cancers, are related to hereditary cancer syndromes 15% to 20% of the time. Genetic testing guidelines for hereditary cancer syndromes are frequently reviewed and updated by the National Comprehensive Cancer Network (NCCN). The purpose of this retrospective analysis is to identify carriers of pathogenic variants or hereditary cancer syndrome who do not meet NCCN criteria for testing and compare the results with previous studies. The data obtained can be used to provide recommendations to assess current guidelines for testing and evaluate the benefit of comprehensive panel testing vs. standard testing for specific hereditary cancer syndromes. This project is a retrospective review of clinical histories of patients who had multigene panel testing between September 2015 and February 2019 through a cancer outreach and risk assessment (CORA) program. Frequencies analyses were performed to analyze results. A total of 233 individuals were included in the analysis: 171 met BRCA1/2 testing criteria, 66 met Lynch syndrome criteria, and 4 met polyposis criteria. Of the individuals meeting established criteria for testing, 39 were identified with pathogenic variants. However, only 10 of these individuals were identified with a pathogenic variant associated with the criteria for which they met. Genetic testing that is limited to only those patients with genes associated with hereditary cancer syndromes may lead to exclusion of other potentially actionable genes, which may impair a patient's ability to receive additional screening or preventative measures.

Co-delivery of paclitaxel and curcumin by biodegradable polymeric nanoparticles for breast cancer chemotherapy

Multi-drug chemotherapy has been one of the most popular strategies for the treatment of malignant tumors, and has achieved desirable therapeutic outcomes. The objective of the present study is to develop biodegradable PCEC nanoparticles (NPs) for the co-delivery of paclitaxel (PTX) and curcumin (CUR), and investigate the antitumor effect of the drug delivery system (DDS: PTX-CUR-NPs) against breast cancer both in vitro and in vivo. The prepared PTX-CUR-NPs had a small size of 27.97 ± 1.87 nm with a low polydispersity index (PDI, 0.197 ± 0.040). The results exhibited slow release of PTX and CUR from the DDS without any burst effect. Further, the PTX-CUR-NPs displayed a dose-dependent cytotoxicity in MCF-7 cells with a higher apoptosis rate (64.29% ± 1.97%) as compared to that of free drugs (PTX + CUR, 34.21% ± 0.81%). The cellular uptake study revealed that the drug loaded PCEC polymeric nanoparticles were more readily uptaken by tumor cells in vitro. To evaluate the in vivo anti-tumor effect, the PTX-CUR-NPs were intravenously administered to BALB/c nude mouse xenografted with MCF-7 cells and the results exhibited significant inhibition of tumor growth with prolonged survival time and reduced side effect when compared with free drugs (PTX + CUR). Moreover, the administration of PTX-CUR-NPs treatment led to lower Ki67 expression (p < 0.05), and enhanced TUNEL positivity (higher apoptosis, p < 0.01) in tumor cells as compared to other treatment groups, suggesting the therapeutic efficacy of the DDS. Altogether, the present study suggests that the DDS PTX-CUR-NPs could be employed for the effective treatment of breast cancers in near future.

Germline Variants in Driver Genes of Breast Cancer and Their Association with Familial and Early-Onset Breast Cancer Risk in a Chilean Population

The genetic variations responsible for tumorigenesis are called driver mutations. In breast cancer (BC), two studies have demonstrated that germline mutations in driver genes linked to sporadic tumors may also influence BC risk. The present study evaluates the association between SNPs and SNP-SNP interaction in driver genes TTN (rs10497520), TBX3 (rs2242442), KMT2D (rs11168827), and MAP3K1 (rs702688 and rs702689) with BC risk in BRCA1/2-negative Chilean families. The SNPs were genotyped in 489 BC cases and 1078 controls by TaqMan Assay. Our data do not support an association between rs702688: A>G or rs702689: G>A and BC risk. The rs10497520-T allele was associated with a decreased risk in patients with family history of BC or early-onset BC (OR = 0.6, p < 0.0001 and OR = 0.7, p = 0.05, respectively). rs2242442-G was associated with a protective effect and rs11168827-C was associated with increased BC risk in families with a strong history of BC (OR = 0.6, p = 0.02 and OR = 1.4, p = 0.05, respectively). As rs10497520-T and rs2242442-G seemed to protect against BC risk, we then evaluated their combined effect. Familial BC risk decreased in a dose-dependent manner with the protective allele count, reflecting an additive effect (p-trend < 10⁻⁴). To our knowledge, this is the first association study of BC driver gene germline variations in a Chilean population.

Effect of HMGN2 on proliferation and apoptosis of MCF-7 breast cancer cells

We investigated the effect of high mobility group protein N2 (HMGN2) on the proliferation and apoptosis of the human MCF-7 breast cancer cell line, and its effect on tumor growth in a subcutaneous heterotopic transplantation tumor model of breast cancer. The cell viability assay was used to verify the effect of the recombinant human HMGN2 on MCF-7 cell proliferation. The Transwell chamber assay was used to verify the effect of HMGN2 on MCF-7 cell migration. Flow cytometry and Hoechst staining were used to detect the effect of HMGN2 on MCF-7 cell apoptosis. MCF-7 was injected to establish a subcutaneous heterotopic transplantation tumor model of breast cancer in nude mice. The size, weight and volume of tumor in each group were compared after the administration of different concentrations of HMGN2 solution around the tumor tissue at day 1, 3, 5 and 7. The tumor tissue was removed and cut into sections, and the apoptotic cells in tumors of nude mice were detected by a TUNEL kit. The CCK-8 assay showed that HMGN2 at different concentrations inhibited the proliferation of the MCF-7 breast cancer cells, and the proliferation of MCF-7 cells were significantly inhibited when the concentration of HMGN2 reached 3 µg/ml (P<0.01). The Transwell chamber assay showed that 3 µg/ml of HMGN2 significantly decreased the migration capacity of MCF-7 cells (P<0.01). Flow cytometry and Hoechst staining showed that 3 µg/ml of HMGN2 significantly increased apoptosis of MCF-7 cells (P<0.01). After the nude mouse model of breast cancer was established, HMGN2 at different concentrations was injected around the tumor tissue at day 1, 3, 5 and 7. We demonstrated that the growth of breast cancer was significantly inhibited when the concentration of HMGN2 reached 15 µg/ml. TUNEL staining showed that the number of apoptotic cells in the 15 µg/ml dose group was significantly higher than that in the control group (P<0.01). Therefore, in vitro and in vivo experiments proved that recombinant human HMGN2 could significantly inhibit the proliferation and migration of breast cancer cells, which increased the apoptosis of breast cancer cells and exerted anti-breast cancer effects, which enriched our understanding of the biological roles of HMGN2.