Promoter Methylation Status Modulate the Expression of Tumor Suppressor (RbL2/p130) Gene in Breast Cancer.
BACKGROUND
Aberrant expression of tumor suppressor genes may correspond to the abnormal cell development and tumorigenesis. Rbl2/p130, a member of retinoblastoma family of proteins, has growth suppressive properties. Numerous studies reported de-regulation of Rbl2/p130 in various types of cancer as a consequence of a number of genetic alterations. However, role of epigenetic mechanisms like DNA methylation in Rbl2/p130 expression remains elusive.


METHODS
In the current study, 76 breast cancer tumors along with normal tissues (n = 76), blood (n = 76) of respective individuals and control blood (n = 50) were analyzed. Rbl2/p130 expression was analyzed by quantitative real time PCR (syber green method). Promoter methylation status was studied through methylation specific PCR of bisulfite converted genomic DNA. Data was analyzed using various statistical tests.


RESULTS
We report significantly reduced Rbl2/p130 expression (P = 0.001) in tumors tissues as compared to control samples. Similarly, Rbl2/p130 expression varies with age and disease stages (P = 0.022), which suggest its involvement in tumor progression. Aberrant promoter methylation (Δmeth) was found in almost all the diseased samples and that was significantly different (P<0.001) with control samples. Similarly, methylation status varies significantly with tumor progression stages (P = 0.022). Hyper-methylation was observed at -1, +3, +15 and +75 of Rbl2/p130 promoter flanking around the TSS. Statistical analysis revealed that Rbl2/p130 expression negatively correlates to its promoter methylation (r = -0.412) in tumor tissues. Our results reflect an epigenetic regulation of Rbl2/p130 expression in breast cancer. This highlights the importance of Rbl2/p130 promoter methylation in breast cancer pathogenesis.
Cancer Genetics and Epigenetics Lab, Department of Biosciences, COMSATS Institute of Information Technology (CIIT), Islamabad, Pakistan.
Farman
F
Ullah
Cancer Genetics and Epigenetics Lab, Department of Biosciences, COMSATS Institute of Information Technology (CIIT), Islamabad, Pakistan.
Taimoor
T
Khan
Department of Biotechnology and Genetic Engineering, Kohat University of Science and Technology (KUST), Kohat, Pakistan.
Nawab
N
Ali
Cancer Genetics and Epigenetics Lab, Department of Biosciences, COMSATS Institute of Information Technology (CIIT), Islamabad, Pakistan.
Faraz Arshad
FA
Malik
Cancer Genetics and Epigenetics Lab, Department of Biosciences, COMSATS Institute of Information Technology (CIIT), Islamabad, Pakistan.
Mahmood Akhtar
MA
Kayani
Cancer Genetics and Epigenetics Lab, Department of Biosciences, COMSATS Institute of Information Technology (CIIT), Islamabad, Pakistan.
Syed Tahir Abbas
ST
Shah
Cancer Genetics and Epigenetics Lab, Department of Biosciences, COMSATS Institute of Information Technology (CIIT), Islamabad, Pakistan.
Muhammad
M
Saeed
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000235:genetics / Q000378:metabolism*; D044127:Epigenesis, Genetic; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008875:Middle Aged; D011401:Promoter Regions, Genetic; D060888:Real-Time Polymerase Chain Reaction; D050717:Retinoblastoma-Like Protein p130 / Q000096:biosynthesis* / Q000235:genetics
D004273:DNA, Neoplasm; C493837:RBL2 protein, human; D050717:Retinoblastoma-Like Protein p130