ARID1B, a member of the human SWI/SNF chromatin remodeling complex, exhibits tumour-suppressor activities in pancreatic cancer cell lines

• Published in: British journal of cancer 2013-05, Vol.108 (10), p.2056-2062
• Main Authors: Khursheed, M, Kolla, J N, Kotapalli, V, Gupta, N, Gowrishankar, S, Uppin, S G, Sastry, R A, Koganti, S, Sundaram, C, Pollack, J R, Bashyam, M D
• Format: Article
• Language: English
• Subjects: 631/45/612/1229; 631/67/1504/1713; Adenocarcinoma - genetics; Adenocarcinoma - metabolism; Adenocarcinoma - pathology; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Cancer Research; Carcinoma, Pancreatic Ductal - genetics; Carcinoma, Pancreatic Ductal - metabolism; Carcinoma, Pancreatic Ductal - pathology; Cell Line, Tumor; Chromosomal Proteins, Non-Histone - genetics; Chromosomal Proteins, Non-Histone - metabolism; Chromosomal Proteins, Non-Histone - physiology; CpG Islands; DNA Methylation; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; DNA-Binding Proteins - physiology; Drug Resistance; Epidemiology; Gastroenterology. Liver. Pancreas. Abdomen; Gene Expression Regulation, Neoplastic; Humans; Liver. Biliary tract. Portal circulation. Exocrine pancreas; Medical sciences; Molecular Diagnostics; Molecular Medicine; Multiple tumors. Solid tumors. Tumors in childhood (general aspects); Oncology; Pancreatic cancer; Pancreatic Neoplasms - genetics; Pancreatic Neoplasms - metabolism; Pancreatic Neoplasms - pathology; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription Factors - physiology; Transfection; Tumor Suppressor Proteins - genetics; Tumor Suppressor Proteins - metabolism; Tumor Suppressor Proteins - physiology; Tumors
• ISSN: 0007-0920; 1532-1827
• DOI: 10.1038/bjc.2013.200

Background: The human ATP-dependent SWItch/sucrose nonfermentable (SWI/SNF) complex functions as a primary chromatin remodeler during ontogeny, as well as in adult life. Several components of the complex have been suggested to function as important regulators of tumorigenesis in various cancers. In the current study, we have characterised a possible tumour suppressor role for the largest subunit of the complex, namely the AT-rich interaction domain 1B (ARID1B). Methods: We performed Azacytidine and Trichostatin A treatments, followed by bisulphite sequencing to determine the possible DNA methylation-induced transcription repression of the gene in pancreatic cancer (PaCa) cell lines. Functional characterisation of effect of ARID1B ectopic expression in MiaPaCa2 PaCa cell line, which harboured ARID1B homozygous deletion, was carried out. Finally, we evaluated ARID1B protein expression in pancreatic tumour samples using immunohistochemistry on a tissue microarray. Results: ARID1B was transcriptionally repressed due to promoter hypermethylation, and ectopic expression severely compromised the ability of MiaPaCa2 cells to form colonies in liquid culture and soft agar. In addition, ARID1B exhibited significantly reduced/loss of expression in PaCa tissue, especially in samples from advanced-stage tumours, when compared with normal pancreas. Conclusion: The results therefore suggest a possible tumour-suppressor function for ARID1B in PaCa, thus adding to the growing list of SWI/SNF components with a similar function. Given the urgent need to design efficient targeted therapies for PaCa, our study assumes significance.