Murine Double Minute 2 Gene (MDM2) rs937283A/G variant significantly increases the susceptibility to breast cancer in Saudi Women

Breast cancer is predominant causes of mortality in women worldwide. Genetic polymorphisms have a significant role in breast cancer aetiology. TP53 and its inhibitor the murine double minute 2 (MDM2) genes encode proteins that have crucial functions in the DNA damage response. The allelic variations within these genes could influence the susceptibility to breast cancer. MDM2 promotor polymorphism rs937283A/G has a role in susceptibility to cancer and modifies the promoter activity. In the present case-control study, the association of MDM2 rs937283A/G polymorphism and breast cancer susceptibility in Saudi women with samples of 137 breast cancer patients, and 98 healthy controls were explored. MDM2 gene polymorphism rs937283A/G was genotyped by polymerase chain reaction restriction fragment length polymorphism and confirmed by sequencing. The results revealed that rs937283A/G variant is significantly increases the risk of breast cancer in Saudi women (p-value = 0.0078). Moreover, rs937283A/G polymorphism was associated with high risk of breast cancer in estrogen positive breast cancer patients (p-value = 0.0088), progesterone positive breast cancer patients (p-value = 0.0043), human epidermal growth factor receptor 2 negative breast cancer patients (p-value = 0.0026), and triple negative breast cancer patients where (p-value = 0.0003). Positive association between increased breast cancer risk and rs937283 variant in premenopausal Saudi women, below 50 years of age, was demonstrated (p-value = 0.0023). Collectively, MDM2 rs937283A/G polymorphism could act as a possible biomarker for breast cancer susceptibility in Saudi women.     

Prospective breast cancer risk factors prediction in Saudi women

Women's health is affected by breast cancer worldwide and Saudi Arabia (SA) is no exception. Malignancy has enormous consequences for social, psychological and public health. The aim of this study was to examine the risk factors for Saudi women from breast cancer using logistic regression models. In 135 patient cases for different stages of breast cancer was used to study case management, 270 healthy women from King Abd Alla Medical City, Mecca, SA were taken to predict the probability of women developing breast cancer, logistic regression was analyzed taking factors such as age, marital status, family history, parity, age at first full-term pregnancy, menopausal status, body mass index (BMI) and breast feeding. The logistic regression model showed that there are important risk factors (age, marital status, family history, parity, age at first full-term pregnancy, menopausal status, body mass index, and breast feeding) in development of breast cancer. Fewer cases were observed in unmarried women, age ≤30, BMI ≤20. In contrast, more cases were found with women age 41–50 married, BMI > 30, a smaller number of children, not breast feeding, age of first pregnancy ≥30, menopausal status age at 46–50. Based on our data there is role of risk factors in developing breast cancer, less BMI, the increase number of children, breast feeding, which are playing as protective factor for breast cancer.     

Fibroblast growth factor receptor 2 (FGFR2): genomic sequence and variations

Fibroblast growth factor receptors (FGFRs) play an important role in development and tumorigenesis. Mutations in FGFR2 cause more than five craniosynostosis syndromes. The FGFR2 genomic structure is the largest of the FGFR family. We have refined and extended the genomic organization of the FGFR2 gene by sequencing more than 119 kb of PACs, cosmids, and PCR products and assembling a region of approximately 175 kb. Although the gene structure has been reported to include only 20 exons, we have verified the presence of at least 22 exons, some of which are alternatively spliced. The sizes of six exons differed from those reported previously. Comparison of our sequence and those in the NCBI database detected more than 300 potential single nucleotide polymorphisms (SNPs). However, sequencing regions containing 52 of these potential SNPs verified only 14 in PCR products generated from 16 CEPH alleles. In contrast, direct sequencing of the CEPH DNAs revealed 21 other polymorphisms. Only one SNP was found in the 2,926 bp of coding sequence. Twenty-seven SNPs, two insertion polymorphisms and five microsatellite polymorphisms are contained in approximately 16.6 kb of non-coding sequence. These data yield an average of one polymorphism for approximately 488 bp of non-coding sequence examined. This collection of SNP, insertion, and repeat polymorphisms will aid future association studies between the FGFR2 gene and human disease and will enhance mutation detection.     

Aberrant hypermethylation of the FGFR2 gene in human gastric cancer cell lines

We have previously shown that fibroblast growth factor receptor 2 (FGFR2) plays an important role in gastric carcinogenesis. In this study, we assessed DNA methylation status in the promoter region of FGFR2 gene in gastric cancer cell lines, and indicated that this region was highly methylated, compared with FGFR2-expressing gastric cancer cell lines. Moreover, the restoration of FGFR2 expression by treating methylated cells with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine strongly suggests that the loss of FGFR2 expression may be due to the aberrant hypermethylation in the promoter region of the FGFR2 gene. Thus, our results suggest that the epigenetic silencing of FGFR2 through DNA methylation in gastric cancer may contribute to tumor progression.     

Quantitative assessment of the association between TAP2 rs241447 polymorphism and cancer risk

The findings regarding the relation of transporter associated with antigen processing (TAP) to cancer risk have been inconsistent. The aim of this study was to comprehensively evaluate the association between TAP2 rs241447 polymorphism and cancer susceptibility. A meta-analysis of nine investigations with 2800 cases and 1620 controls was conducted to gain a better understanding of the effect of TAP2 rs241447 polymorphism on cancer risk. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the strength of the correlation between TAP2 gene polymorphism and cancer susceptibility. The pooled results from TAP2 rs241447 polymorphism showed a decreased risk of cancer in two dominant genetic models (GG + AG vs AA: OR = 0.86, 95% CI, 0.75-0.99; AG vs AA: OR = 0.85, 95% CI, 0.73-0.99). From the subgroup analysis, decreased cancer susceptibility was found in Caucasians (GG + AG vs AA: OR = 0.82, 95% CI, 0.68-0.99), especially among the subgroup of cervical carcinoma (GG + AG vs AA: OR = 0.82, 95% CI, 0.69-0.96; AG vs AA: OR = 0.83, 95% CI, 0.70-0.99). Overall, the results suggest that TAP2 rs241447 polymorphism contributes to decreased cancer susceptibility.     

Epidermal growth factor receptor coexpression modulates susceptibility to Herceptin in HER2/neu overexpressing breast cancer cells via specific erbB-receptor interaction and activation

BACKGROUND: Growth factors and Herceptin specifically and differentially modulate cell proliferation of tumor cells. However, the mechanism of action on erbB-receptor level is incompletely understood. We evaluated Herceptin's capacity to modulate erbB-receptor activation and interaction on the cell surface level and thereby potentially impair cell proliferation of HER2/neu (c-erbB2) overexpressing breast cancer cells, both in the presence and absence of relevant growth factors. METHODS: BT474 and SK-BR-3 breast cancer cell lines were treated with Epidermal Growth Factor (EGF), Heregulin, and with Herceptin in different combinations. Kinetics of cell proliferation were evaluated flow cytometrically based on BrdU-labeling. Fluorescence Resonance Energy Transfer, ELISAs and phosphorylation site specific Western Blotting was performed to investigate erbB-receptor interaction and activation. RESULTS: EGF induced EGFR/EGFR and EGFR/c-erbB2 interactions correlate with stimulation of cell proliferation in BT474 cells. Both homo- and heterodimerization are considerably less pronounced in SK-BR-3 cells and heterointeraction is additionally reduced by EGF treatment, causing inhibition of cell proliferation. Heregulin stimulates cell proliferation extensively in both cell lines. Herceptin drives BT474 cells more efficiently into quiescence than it does with SK-BR-3 cells and thereby blocks cell cycle progress. In SK-BR-3 Herceptin treatment causes c-erbB2 phosphorylation of Y877 and Y1248, EGF induces Y877 and Y1112 phosphorylation. The Y1112 phosphorylation site, activated by EGF in SK-BR-3 cell, is bypassed in BT474. In addition the inhibitory capacity of Herceptin on BT474 and SK-BR-3 cell proliferation depends on the presence and absence of growth factors to a various extent. CONCLUSION: The growth inhibitory effect of Herceptin on c-erbB2 overexpressing breast cancer cells is considerably modulated by EGFR coexpression and consequently EGFR/c-erbB2 homo- and heterointeractions, as well as the presence or absence of growth factors. C-erbB2 overexpression alone is insufficient to predict the impact of growth factors and antibodies on cell proliferation. The optimization and specification of therapeutic approaches based on erbB-receptor targeting requires to account for EGFR coexpression as well as the potential presence of erbB-receptor relevant growth factors.     

Fibroblast growth factor receptor 3 (FGFR3) is a strong heat shock protein 90 (Hsp90) client: implications for therapeutic manipulation

Fibroblast growth factor receptor 3 (FGFR3) is a key regulator of growth and differentiation, whose aberrant activation causes a number of genetic diseases including achondroplasia and cancer. Hsp90 is a specialized molecular chaperone involved in stabilizing a select set of proteins termed clients. Here, we delineate the relationship of Hsp90 and co-chaperone Cdc37 with FGFR3 and the FGFR family. FGFR3 strongly associates with these chaperone complexes and depends on them for stability and function. Inhibition of Hsp90 function using the geldanamycin analog 17-AAG induces the ubiquitination and degradation of FGFR3 and reduces the signaling capacity of FGFR3. Other FGFRs weakly interact with these chaperones and are differentially influenced by Hsp90 inhibition. The Hsp90-related ubiquitin ligase CHIP is able to interact and destabilize FGFR3. Our results establish FGFR3 as a strong Hsp90 client and suggest that modulating Hsp90 chaperone complexes may beneficially influence the stability and function of FGFR3 in disease.     

Vascular endothelial growth factor receptor-2 in breast cancer

Investigations over the last decade have established the essential role of growth factors and their receptors during angiogenesis and carcinogenesis. The vascular endothelial growth factor receptor (VEGFR) family in mammals contains three members, VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1) and VEGFR-3 (Flt-4), which are transmembrane tyrosine kinase receptors that regulate the formation of blood and lymphatic vessels. In the early 1990s, the above VEGFR was structurally characterized by cDNA cloning. Among these three receptors, VEGFR-2 is generally recognized to have a principal role in mediating VEGF-induced responses. VEGFR-2 is considered as the earliest marker for endothelial cell development. Importantly, VEGFR-2 directly regulates tumor angiogenesis. Therefore, several inhibitors of VEGFR-2 have been developed and many of them are now in clinical trials. In addition to targeting endothelial cells, the VEGF/VEGFR-2 system works as an essential autocrine/paracrine process for cancer cell proliferation and survival. Recent studies mark the continuous and increased interest in this related, but distinct, function of VEGF/VEGFR-2 in cancer cells: the autocrine/paracrine loop. Several mechanisms regulate VEGFR-2 levels and modulate its role in tumor angiogenesis and physiologic functions, i.e.: cellular localization/trafficking, regulation of cis-elements of promoter, epigenetic regulation and signaling from Notch, cytokines/growth factors and estrogen, etc. In this review, we will focus on updated information regarding VEGFR-2 research with respect to the molecular mechanisms of VEGFR-2 regulation in human breast cancer. Investigations in the activation, function, and regulation of VEGFR-2 in breast cancer will allow the development of new pharmacological strategies aimed at directly targeting cancer cell proliferation and survival.     

PVT1 (rs13281615) and miR-146a (rs2910164) polymorphisms affect the prognosis of colon cancer by regulating COX2 expression and cell apoptosis

In this study, we aimed to investigate the potential correlation between rs13281615/rs2910164 polymorphisms and the prognosis of colon cancer (CC). Taqman was utilized to genotype the rs13281615/rs2910164 polymorphisms in recruited subjects. Kaplan–Meier survival curves were calculated to study the prognostic values of different genotypes of rs13281615/rs2910164 polymorphisms. Real-time polymerase chain reaction, enzyme-linked immunosorbent assay, immunohistochemistry, and terminal deoxynucleotidyl transferase dUTP nick-end labeling assays were conducted to establish a potential signaling pathway underlying the role of rs13281615/rs2910164 polymorphisms, whereas bioinformatics analysis and luciferase reporter assays were performed to identify plasmacytoma variant translocation 1 (PVT1) and cyclooxygenase-2 (COX2) as targets of microRNA-146a (miR-146a). No significant difference was observed in respect to clinical characteristics among subjects with different genotypes. However, patients genotyped as GG/CC + GC showed the lowest chance of survival, whereas patients of GA + AA/GG genotype showed the highest chance of survival. Moreover, the relative expressions of PVT1, prostaglandin E2 (PGE2), and COX2 were the lowest and the relative expression of miR-146a was the highest in GA + AA/GG subjects, validating the roles of PVT1, miR-146a, and COX2 in CC. In addition, both PVT1 and COX2 were identified as virtual targets of miR-146a, and the luciferase activities of cells cotransfected with wild-type PVT1/COX2 and miR-146a mimics were significantly reduced. Moreover, the presence of PVT1 decreased the level of miR-146a whereas increasing the messenger RNA and protein levels of COX2, thus establishing a PVT1/miR-146a/COX2 signaling pathway underlying the pathogenesis of CC. The presence of rs13281615 G > A polymorphism on PVT1 and the rs2910164 C > G polymorphism on miR-146a contributes to a favorable prognosis in CC patients via modulating the activity of the PVT1/miR-146a/COX2 signaling pathway.     

Fibroblast growth factor receptor 1 (FGFR1) tyrosine phosphorylation regulates binding of FGFR substrate 2alpha (FRS2alpha) but not FRS2 to the receptor

Binding of the fibroblast growth factor (FGF) to the FGF receptor (FGFR) tyrosine kinase leads to receptor tyrosine autophosphorylation as well as phosphorylation of multiple downstream signaling molecules that are recruited to the receptor either by direct binding or through adaptor proteins. The FGFR substrate 2 (FRS2) family consists of two members, FRS2alpha and FRS2beta, and has been shown to recruit multiple signaling molecules, including Grb2 and Shp2, to FGFR1. To better understand how FRS2 interacted with FGFR1, in vivo binding assays with coexpressed FGFR1 and FRS2 recombinant proteins in mammalian cells were carried out. The results showed that the interaction of full-length FRS2alpha, but not FRS2beta, with FGFR1 was enhanced by activation of the receptor kinase. The truncated FRS2alpha mutant that was comprised only of the phosphotyrosine-binding domain (PTB) bound FGFR1 constitutively, suggesting that the C-terminal sequence downstream the PTB domain inhibited the PTB-FGFR1 binding. Inactivation of the FGFR1 kinase and substitutions of tyrosine phosphorylation sites of FGFR1, but not FRS2alpha, reduced binding of FGFR1 with FRS2alpha. The results suggest that although the tyrosine autophosphorylation sites of FGFR1 did not constitute the binding sites for FRS2alpha, phosphorylation of these residues was essential for optimal interaction with FRS2alpha. In addition, it was demonstrated that the Grb2-binding sites of FRS2alpha are essential for mediating signals of FGFR1 to activate the FiRE enhancer of the mouse syndecan 1 gene. The results, for the first time, demonstrate the specific signals mediated by the Grb2-binding sites and further our understanding of FGF signal transmission at the adaptor level.     

Fibroblast growth factor receptor 1 regulates the differentiation and activation of osteoclasts through Erk1/2 pathway

To elucidate the direct role and mechanism of FGFR1 signaling in the differentiation and activation of osteoclasts, we conditionally inactivated FGFR1 in bone marrow monocytes and mature osteoclasts of mice. Mice deficient in FGFR1 (Fgfr1^−/−) exhibited misregulated bone remodeling with reduced osteoclast number and impaired osteoclast function. In vitro assay demonstrated that the number of tartrate-resistant acid phosphatase (TRAP) positive osteoclasts derived from bone marrow monocytes of Fgfr1^−/− mice was significantly diminished. The bone resorption activity of mature osteoclasts derived from Fgfr1^−/− mice was also suppressed. Further analysis showed that the osteoclasts with FGFR1 deficiency exhibited downregulated expression of genes related to osteoclastic activity including TRAP and MMP-9. The phosphorylation of Erk1/2 mitogen-activated protein (MAP) kinase was also decreased. Our results suggest that FGFR1 is indispensable for complete differentiation and activation of osteoclasts in mice.     

SARS-CoV-2 cell receptor gene ACE2 -mediated immunomodulation in breast cancer subtypes

The recent outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has impacted the world severely. The binding of the SARS-CoV-2 virus to the angiotensin-converting enzyme 2 (ACE2) and its intake by the host cell is a necessary step for infection. ACE2 has garnered widespread therapeutic possibility as it is entry/interactive point for SARS-CoV-2, responsible for coronavirus disease 2019 (COVID-19) pandemic and providing a critical regulator for immune modulation in various disease. Patients with suffering from cancer always being on the verge of being immune compromised therefore gaining knowledge about how SARS-CoV-2 viruses affecting immune cells in human cancers will provides us new opportunities for preventing or treating virus-associated cancers. Despite COVID-19 pandemic got center stage at present time, however very little research being explores, which increase our knowledge in context with how SARS-CoV-2 infection affect cancer a cellular level. Therefore, in light of the ACE-2 as an important contributor of COVID-19 global, we analyzed correlation between ACE2 and tumor immune infiltration (TIL) level and the type markers of immune cells were investigated in breast cancer subtypes by using TIMER database. Our findings shed light on the immunomodulatory role of ACE2 in the luminal A subtype which may play crucial role in imparting therapeutic resistance in this cancer subtype.     

Genetic diversity and population genetic structure of six dromedary camel (camelus dromedarius) populations in Saudi Arabia

Camels are an integral and essential component of the Saudi Arabian heritage. The genetic diversity and population genetic structure of dromedary camels are poorly documented in Saudi Arabia so this study was carried out to investigate the genetic diversity of both local and exotic camel breeds. The genetic diversity was evaluated within and among camel populations using 21 microsatellite loci. Hair and blood samples were collected from 296 unrelated animals representing 4 different local breeds, namely Majaheem (MG), Maghateer (MJ), Sofr (SO), and Shaul (SH), and two exotic breeds namely Sawahli (SL) and Somali (SU). Nineteen out of 21 microsatellite loci generated multi-locus fingerprints for the studied camel individuals, with an average of 13.3 alleles per locus. Based on the genetic analyses, the camels were divided into two groups: one contained the Saudi indigenous populations (MG, MJ, SH and SO) and the other contained the non-Saudi ones (SU and SL). There was very little gene flow occurring between the two groups. The African origin of SU and SL breeds may explain their close genetic relationship. It is anticipated that the genetic diversity assessment is important to preserve local camel genetic resources and develop future breeding programs to improve camel productivity.     

CpG/CpNpG motifs in the coding region are preferred sites for mutagenesis in the breast cancer susceptibility genes

The range of BRCA1/BRCA2 gene mutations is diverse and the mechanism accounting for this heterogeneity is obscure. To gain insight into the endogenous mutational mechanisms involved, we evaluated the association of specific sequences (i.e. CpG/CpNpG motifs, homonucleotides, short repeats) and mutations within the genes. We classified 1337 published mutations in BRCA1 (1765 BRCA2 mutations) for each specific sequence, and employed computer simulation combined with mathematical calculations to estimate the true underlying tendency of mutation occurrence. Interestingly, we found no mutational bias to homonucleotides and repeats in deletions/insertions and substitutions but striking bias to CpG/CpNpG in substitutions in both genes. This suggests that methylation-dependent DNA alterations would be a major mechanism for mutagenesis.     

Polymorphisms in the promoter region of ESR2 gene and breast cancer susceptibility

Genetic variations like single nucleotide polymorphisms (SNPs) in genes involved in estrogen biosynthesis, metabolism and signal transduction have been suggested to affect breast cancer susceptibility. In this study we tested the hypothesis that polymorphisms in the promoter of ESR2 gene may be associated with increased risk for breast cancer. We analyzed three SNPs in the promoter region of human ESR2 gene by means of allele-specific tetra-primer PCR. A total of 318 sporadic breast cancer cases and 318 age-matched controls were included in the study. With regard to homozygous genotypes, women with sporadic breast cancer more frequently carried the CC genotype of ESR2 promoter SNP rs2987983 (OR 1.99, p = 0.005). Calculation of allele positivity demonstrated that presence of T allele of this SNP was more frequent in healthy women. Our data suggest that a SNP in the promoter region of ESR2 gene might be able to affect breast cancer risk. These results further support the emerging hypothesis that ERβ is an important factor in breast cancer development.     

The bovine fibroblast growth factor receptor 3 (FGFR3) gene is not the locus responsible for bovine chondrodysplastic dwarfism in Japanese brown cattle

Fibroblast growth factor receptor 3 (FGFR3) is one of the four distinct membrane-spanning tyrosine kinase receptors for fibroblast growth factors. The FGFR3 is a negative regulator of endochondral ossification and mutations in the FGFR3 gene have been found in patients of human hereditary diseases with chondrodysplastic phenotypes. Recently, we mapped the locus responsible for hereditary chondrodysplastic dwarfism in Japanese brown cattle to the distal region of bovine chromosome 6 close to the FGFR3 gene, suggesting that FGFR3 was a positional candidate gene for this disorder. In the present study, we isolated complementary DNA (cDNA) clones containing the entire coding region of the bovine FGFR3 gene. Comparison of the nucleotide sequence between affected and normal animals revealed no disease-specific differences in the deduced amino acid sequences. We further refined the localization of FGFR3 by radiation hybrid mapping, which is distinct from that of the disease locus. Therefore we conclude that bovine chondrodysplastic dwarfism in Japanese brown cattle is not caused by mutation in the FGFR3 gene.     

Frequency of the allelic variant c.1150T > C in exon 10 of the fibroblast growth factor receptor 3 (FGFR3) gene is not increased in patients with pathogenic mutations and related chondrodysplasia phenotypes

Mutations in the FGFR3 gene cause the phenotypic spectrum of FGFR3 chondrodysplasias ranging from lethal forms to the milder phenotype seen in hypochondroplasia (Hch). The p.N540K mutation in the FGFR3 gene occurs in ∼70% of individuals with Hch, and nearly 30% of individuals with the Hch phenotype have no mutations in the FGFR3, which suggests genetic heterogeneity. The identification of a severe case of Hch associated with the typical mutation c.1620C > A and the occurrence of a c.1150T > C change that resulted in a p.F384L in exon 10, together with the suspicion that this second change could be a modulator of the phenotype, prompted us to investigate this hypothesis in a cohort of patients. An analysis of 48 patients with FGFR3 chondrodysplasia phenotypes and 330 healthy (control) individuals revealed no significant difference in the frequency of the C allele at the c.1150 position (p = 0.34). One patient carrying the combination `pathogenic mutation plus the allelic variant c.1150T > C’ had a typical achondroplasia (Ach) phenotype. In addition, three other patients with atypical phenotypes showed no association with the allelic variant. Together, these results do not support the hypothesis of a modulatory role for the c.1150T > C change in the FGFR3 gene.