The single nucleotide polymorphism +936 C/T VEGF is associated with human epidermal growth factor receptor 2 expression in Moroccan breast cancer women

A Review of Cancer Genetics and Genomics Studies in Africa

Cancer is the second leading cause of death globally and is projected to overtake infectious disease as the leading cause of mortality in Africa within the next two decades. Cancer is a group of genomic diseases that presents with intra- and inter-population unique phenotypes, with Black populations having the burden of morbidity and mortality for most types. At large, the prevention and treatment of cancers have been propelled by the understanding of the genetic make-up of the disease of mostly non-African populations. By the same token, there is a wide knowledge gap in understanding the underlying genetic causes of, and genomic alterations associated with, cancer among black Africans. Accordingly, we performed a review of the literature to survey existing studies on cancer genetics/genomics and curated findings pertaining to publications across multiple cancer types conducted on African populations. We used PubMed MeSH terms to retrieve the relevant publications from 1990 to December 2019. The metadata of these publications were extracted using R text mining packages: RISmed and Pubmed.mineR. The data showed that only 0.329% of cancer publications globally were on Africa, and only 0.016% were on cancer genetics/genomics from Africa. Although the most prevalent cancers in Africa are cancers of the breast, cervix, uterus, and prostate, publications representing breast, colorectal, liver, and blood cancers were the most frequent in our review. The most frequently reported cancer genes were BRCA1, BRCA2, and TP53. Next, the genes reported in the reviewed publications’ abstracts were extracted and annotated into three gene ontology classes. Genes in the cellular component class were mostly associated with cell part and organelle part, while those in biological process and molecular function classes were mainly associated with cell process, biological regulation, and binding, and catalytic activity, respectively. Overall, this review highlights the paucity of research on cancer genomics on African populations, identified gaps, and discussed the need for concerted efforts to encourage more research on cancer genomics in Africa.

Association between VEGF single nucleotide polymorphism and breast cancer in the Northern China Han population

PURPOSE

To investigate the associations of four commonly studied single nucleotide polymorphisms (SNP) of the vascular endothelial growth factor (VEGF), including -460T/C (rs833061), - 634G/C (rs2010963), - 2578C/A (rs699947), and +936T/C (rs3025039), with the incidence, aggressiveness, and tumor markers expression of breast cancer in the Northern China Han population.

METHODS

Followed the genomic DNA extraction, a total of 259 patients with breast cancer (case group) and 273 healthy women (control group) underwent genotyping by PCR-LDR SNP assays. The associations between VEGF gene polymorphisms and the incidence, aggressiveness, and tumor markers expression of breast cancer were analyzed.

RESULTS

Significant differences were observed in allele frequency and genotype distribution of - 634G/C between breast cancer cases and healthy controls (p = 0.006, 0.013). Individuals who carry the G allele more likely had a lower risk of breast cancer (OR, 0.866, 95% CI 0.782-0.959). Compared with CC genotype carriers, women who had the CG and GG genotypes demonstrated a relatively lower risk (OR, 0.860, 95% CI 0.757-0.978, p = 0.022; OR, 0.778, 95% CI, 0.656-0.924, p = 0.004, respectively). When we stratified the group of patients according to the status of tumor markers, a significant association of - 634G/C SNP and Ki-67 expression was observed. The CC genotype carriers were more likely to be characterized by high expression of Ki-67 (p = 0.031). Further analysis showed that the - 460T/-634C/-2578C/+936C haplotype was more associated with a higher risk of breast cancer (OR, 1.445, 95% CI 1.123-1.859, p = 0.004), whereas the - 460T/- 634G/- 2578C/+936C one was associated with a lower risk (OR, 0.736, 95% CI 0.563-0.963, p = 0.025).

CONCLUSIONS

In the present study, we concluded that VEGF gene - 634G/C polymorphism is related to the incidence of breast cancer in the Han population in Northern China and also might be associated with tumor proliferation index Ki-67.

Genetics of breast cancer in African populations: a literature review

Breast cancer (BC) is one of the most complex, diverse and leading cause of death in women worldwide. The present investigation aims to explore genes panel associated with BC in different African regions, and compare them to those studied worldwide.

We extracted relevant information from 43 studies performed in Africa using the following criteria: case-control study, association between genetic variations and BC risk. Data were provided on mutations and polymorphisms associated with BC without fixing a specific date. Case-only studies and clinical trials were excluded.

Our study revealed that the majority of African BC genetic studies remain restricted to the investigation of BRCA1 and BRCA2 genes and differences in their mutations spectrum. Therefore, it is necessary to encourage African researchers to characterize more genes involved in BC using methods generating global information such as next-generation sequencing in order to guide specific and more effective therapeutic strategies for the African community.

Potential Impact of Vascular Endothelial Growth Factor Gene Variation (-2578C>A) on Breast Cancer Susceptibility in Saudi Arabia: a Case-Control Study

Aim:

VEGF gene polymorphisms can induce either increase or inhibition of VEGF secretion, with altered promoter activity. The VEGF rs699947 SNP is located in the promoter region and is associated with susceptibility to breast carcinoma development. Here, we investigated the association of the -2578C>A polymorphism in the VEGF gene with breast cancer risk in Saudi women.

Methodology:

Genotyping of the VEGF-gene variation (-2578A>C) was performed using the amplification refractory mutation system PCR. We investigated the association of VEGF gene variants with different clinicopathological features of breast cancer patients.

Results:

A significant difference was observed in genotype distribution among the breast cancer cases and sex matched healthy controls (p=0.03). The frequencies of the three genotypes CC, CA, AA found in the patient samples were 37%, 45% and 18% and in the healthy controls were 54%,37%, and 09% respectively. An increased risk of developing breast cancer in Saudi women was associated with the VEGF −2578 AA genotype (OR = 2.91, 95 % CI, 1.18-7.20; p = 0.01; RR 1.78 (1.01-3.11 p=0.01), the VEGF −2578 A allele (OR = 1.79, 95 % CI, 1.17-2.73; p = 0.004: RR 1.35 1.07-1.71) and the VEGFR-(CA+ AA) (OR 1.99 1.13-3.51; RR 1.401.0-1.85). Thus the A allele increased the risk of BC when compared with C allele. When we stratified groups of patients according to the status of tumor markers, stage, age and metastasis, statistically significant associations with −2578 C/A SNP were revealed.

Conclusion:

Our data showed a significant association of the VEGF -2578C>A polymorphism with BC susceptibility in Saudi women. The VEGF -2578AA homozygote significantly increases the risk and can be useful as a predisposing genetic marker. Further studies with larger sample sizes are necessary to confirm our findings.

Significant association between ERCC2 and MTHR polymorphisms and breast cancer susceptibility in Moroccan population: genotype and haplotype analysis in a case-control study

Background

Genetic determinants of breast cancer (BC) remained largely unknown in the majority of Moroccan patients. The purpose of this study was to explore the association of ERCC2 and MTHFR polymorphisms with genetic susceptibility to breast cancer in Moroccan population.

Methods

We genotyped ERCC2 polymorphisms (rs1799793 (G934A) and rs13181 (A2251C)) and MTHFR polymorphisms (rs1801133 (C677T) and rs1801131 (A1298C)) using TaqMan SNP Genotyping Assays. Genotypes were compared in 151 BC cases and 156 population-matched controls. Allelic, genotypic and haplotype associations with the risk and clinicopathological features of BC were assessed using logistic regression analyses.

Results

ERCC2-rs1799793-AA genotype was associated with high risk of BC compared to wild type genotype (recessive model: OR: 2.90, 95% CI: 1.34–6.26, p = 0.0069) even after Bonferroni correction (p < 0,0125). MTHFR rs1801133-TT genotype was associated with increased risk of BC (recessive model, OR: 2.49, 95% CI: 1.17–5.29, p = 0.017) but the association turned insignificant after Bonferroni correction. For the rest of SNPs, no statistical associations to BC risk were detected.

Significant association with clinical features was detected for MTHFR-rs1801133-TC genotype with early age at diagnosis and familial BC. Following Bonferroni correction, only association with familial BC remained significant. MTHFR-rs1801131-CC genotype was associated with sporadic BC. ERCC2-rs1799793-AA genotype correlated with ER+ and PR+ breast cancer. ERCC2-rs13181-CA genotype was significantly associated large tumors (T ≥ 3) in BC patients. None of these associations passed Bonferroni correction.

Haplotype analysis showed that ERCC2 A-C haplotype was significantly associated with increased BC risk (OR: 3.71, 95% CI: 1.7–8.12, p = 0.0002 and p = 0.0008 before and after Bonferroni correction, respectively) and positive expression of ER and PR in BC patients. ERCC2 G-C haplotype was correlated with PR negative and larger tumor (T4). We did not find any MTHFR haplotypes associated with BC susceptibility. However, the less common haplotype MTHFR T-C was more frequent in young patients and in familial breast cancer, while MTHFR C-C haplotype was associated with sporadic BC form.

Conclusions

Our findings are a first observation of association between ERCC2 SNPs and breast cancer in Moroccan population. The results suggested that ERCC2 and MTHFR polymorphisms may be reliable for assessing risk and prognosis of BC in Moroccan population.

Association Between Vascular Endothelial Growth Factor Gene Polymorphisms with Breast Cancer Risk in an Iranian Population

Breast cancer (BC) is one of the most causes of death in women worldwide. It affects Iranian female population approximately a decade earlier than those in other parts of the world. Previous studies have shown that vascular endothelial growth factor (VEGF) gene variants were associated with BC risk. The current study aimed to evaluate the impact of VEGF rs3025039 (+936C>T), rs2010963 (+405C>G), rs833061 (-460T>C), rs699947 (-2578C>A), and rs35569394 (18-bp I/D) polymorphisms on BC risk in an Iranian population in southeast of Iran. This case–control study was done on 250 BC patients and 215 healthy women. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) or PCR was used to genotype the polymorphisms. Our findings showed that VEGF rs699947 variant increased the risk of BC (OR = 1.71, 95% CI = 1.15–2.54, P = 0.009, CA vs CC; OR = 2.12, 95% CI = 1.14–3.93, P = 0.021, AA vs CC; OR = 1.78, 95% CI = 1.22–2.60, P = 0.004, CA+AA vs CC; OR = 1.47, 95% CI = 1.12–1.92, P = 0.005, A vs C). The VEGF rs3025039, rs2010963, rs833061, and rs35569394 variants were not associated with risk/protection of BC. In conclusion, our results proposed that VEGF rs699947 polymorphism may increase the risk of BC development. Furthers studies with larger sample sizes and different ethnicities are necessary to confirm our findings.