ABSTRACT
AIMS: RAD51 participates in homologous recombination repair (HRR) of double-stranded DNA breaks (DSBs) which may cause genomic instability and cancer. The aim of this study was to investigate RAD51 gene expression at transcriptional and translational levels to measure mRNA and protein level and to correlate its relationship with proliferation marker, Ki67 in thyroid cancer patients. This study also explored correlation of these genes with different clinicopathological parameters of the study cohort by Spearman's rank correlation coefficient. METHODS: Quantitative real time polymerase chain reaction (qRT-PCR) and immunohistochemistry were used to detect mRNA transcript levels and protein expression of RAD51 and Ki67 in 102 cases of thyroid cancer tissues and equal number of uninvolved healthy thyroid tissue controls. RESULTS: Data showed that expression for both RAD51 and Ki67 was significantly increased in thyroid cancer (p<0.001). High RAD51 and Ki67 expression was associated with later stages, poor tissue differentiation, large tumor size, positive lymph node metastasis and distant metastasis. The correlation analysis demonstrated a strong positive correlation (r=0.461) between RAD51 and Ki67 on mRNA level and on protein level (r=0.866). Strong correlation was observed between clinicopathological characteristics and selected molecules. CONCLUSION: The present study concluded that upregulation of RAD51 and overexpression of Ki67 may be associated with the progression of thyroid cancer.
Subject(s)
Gene Expression Regulation, Neoplastic , Ki-67 Antigen/metabolism , Rad51 Recombinase/metabolism , Thyroid Neoplasms/genetics , Disease Progression , Female , Genetic Markers , Humans , Immunohistochemistry , Ki-67 Antigen/genetics , Lymphatic Metastasis/genetics , Male , Middle Aged , Neoplasm Metastasis , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rad51 Recombinase/genetics , Up-RegulationABSTRACT
BACKGROUND: Spleen Tyrosine Kinase (SYK) belongs to non-receptor tyrosine Kinase family, which normally expresses in epithelial breast tissues and acts as a tumor suppressor gene. OBJECTIVE: Analysis of mutations in the SYK gene and deregulation of SYK transcripts by miRNA in breast cancer was studied. METHODS: All exons and exon/intron boundaries of SYK gene were amplified and sequenced in blood samples of 207 breast cancer cases and 200 matched controls using PCR-single stranded conformational polymorphism method. RESULTS: Sequence analysis revealed 10 novel mutations in breast cancer patients. Among these 6 mutations (Ala 161Pro, His162Tyr, Phe191Tyr, Val 535Gly, Ser 556lIe and Lys536Gln) were found in exonic region and 4 (26249 T>A, 63941 G>A, 63981G>C and 86548T>A) were found in intronic region. All of these mutations are associated with â¼ 5 folds (p< 0.0001) increase in breast cancer risk in present study cohort. Regulation of SYK transcripts by miRNA was also analyzed using in silico bioinformatics tools, exon 6's mutation (Phe191Tyr) was found to have altered interaction with miR-873. CONCLUSION: Overall novel mutations in SYK gene and in silico analysis revealed that these mutations are crucial and might be responsible for altered expression of SYK.
Subject(s)
Breast Neoplasms/genetics , MicroRNAs/genetics , Mutation, Missense/genetics , Syk Kinase/genetics , Adolescent , Adult , Aged , Base Sequence , Binding Sites , Female , Humans , Middle Aged , Polymorphism, Single-Stranded Conformational/genetics , Sequence Alignment , Sequence Analysis, DNA , Young AdultABSTRACT
Genetic polymorphisms in homologous recombination repair genes cause an abnormal development of cancerous cells. In the present study we evaluated the possibility of breast cancer association with single nucleotide polymorphisms of RAD51, XRCC2 and XRCC3 genes. Polymorphisms selected in this study were RAD51 135G/C, XRCC2 Arg188His; and XRCC3 Thr241Met. Each polymorphism was genotyped using Polymerase chain reaction-restriction fragment length polymorphism in study cohort of 306 females (156 breast cancer patients and 150 controls). We observed that heterozygous variant genotype (GC) of RAD51 135 G/C polymorphism was associated with a significantly (OR=2.70; 95%CI (0.63-1.79); p<0.03) increased risk of breast cancer. In case of the XRCC3 gene we observed that frequency of heterozygous (OR=2.88; 95%CI (1.02-8.14); p<0.02) and homozygous (OR=1.46; 95%CI (0.89-2.40); p<0.04) genotype of Thr241Met polymorphism were significantly higher in breast cancer patients. For the Arg188His polymorphism of XRCC2, ~2fold increase in breast cancer risk (OR=1.6, 95%CI = 0.73-3.50) was associated with GA genotype with a p value for trend of 0.03. Our results suggest that the 135G/C polymorphism of the RAD51, Thr241Met polymorphism of XRCC3 and Arg188His polymorphism of XRCC2 can be independent markers of breast cancer risk in Pakistan.
