title: PSMB9 codon 60 polymorphisms have no impact on the activity of the immunoproteasome catalytic subunit B1i expressed in multiple types of solid cancer.
abstract: The proteasome is a key regulator of cellular protein homeostasis and is a clinically validated anticancer target. The immunoproteasome, a subtype of proteasome expressed mainly in hematopoietic cells, was initially recognized for its role in antigen presentation during the immune response. Recently, the immunoproteasome has been implicated in several disease conditions including cancer and autoimmune disorders, but many of the factors contributing to these pathological processes remain unknown. In particular, the codon 60 polymorphism of the PSMB9 gene encoding the β1i immunoproteasome catalytic subunit has been investigated in the context of a variety of diseases. Despite this, previous studies have so far reported inconsistent findings regarding the impact of this polymorphism on proteasome activity. Thus, we set out to investigate the impact of the PSMB9 codon 60 polymorphism on the expression and activity of the β1i immunoproteasome subunit in a panel of human cancer cell lines. The β1i-selective fluorogenic substrate Acetyl-Pro-Ala-Leu-7-amino-4-methylcoumarin was used to specifically measure β1i catalytic activity. Our results indicate that the codon 60 Arg/His polymorphism does not significantly alter the expression and activity of β1i among the cell lines tested. Additionally, we also examined the expression of β1i in clinical samples from colon and pancreatic cancer patients. Our immunohistochemical analyses showed that ≈ 70% of clinical colon cancer samples and ≈ 53% of pancreatic cancer samples have detectable β1i expression. Taken together, our results indicate that the β1i subunit of the immunoproteasome is frequently expressed in colon and pancreatic cancers but that the codon 60 genetic variants of β1i display similar catalytic activities and are unlikely to contribute to the significant inter-cell-line and inter-individual variabilities in the immunoproteasome activity.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, United States of America.
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Park
authors.forename: Lin
authors.initials: L
authors.lastname: Ao
authors.forename: Zachary
authors.initials: Z
authors.lastname: Miller
authors.forename: Kyungbo
authors.initials: K
authors.lastname: Kim
authors.forename: Ying
authors.initials: Y
authors.lastname: Wu
authors.forename: Eun Ryoung
authors.initials: ER
authors.lastname: Jang
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Lee
authors.forename: Kyung Bo
authors.initials: KB
authors.lastname: Kim
authors.forename: Wooin
authors.initials: W
authors.lastname: Lee
mesh_terms: D019943:Amino Acid Substitution; D055162:Biocatalysis; D020134:Catalytic Domain / Q000235:genetics; D045744:Cell Line, Tumor; D003062:Codon / Q000235:genetics*; D003110:Colonic Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D003546:Cysteine Endopeptidases / Q000235:genetics* / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D005838:Genotype; D045325:HCT116 Cells; D006801:Humans; D006868:Hydrolysis; D015151:Immunoblotting; D007150:Immunohistochemistry; D061986:MCF-7 Cells; D009369:Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D011110:Polymorphism, Genetic; D046888:Tissue Array Analysis
chemical_list: D003062:Codon; D005456:Fluorescent Dyes; C071313:LMP-2 protein; D003546:Cysteine Endopeptidases
references.citation: Semin Hematol. 2012 Jul;49(3):258-62
references.pmid: 22726549
references.citation: J Biol Chem. 2008 Dec 5;283(49):34423-31
references.pmid: 18829465
references.citation: Am J Hum Genet. 1995 Feb;56(2):528-34
references.pmid: 7847389
references.citation: Chem Rev. 2009 Apr;109(4):1509-36
references.pmid: 19265443
references.citation: Eur J Immunogenet. 2000 Feb;27(1):5-16
references.pmid: 10651845
references.citation: Biol Chem. 2006 Apr;387(4):417-29
references.pmid: 16606340
references.citation: Genes Immun. 2002 Sep;3(6):373-7
references.pmid: 12209365
references.citation: Int J Oncol. 2000 Jun;16(6):1159-63
references.pmid: 10811990
references.citation: Methods Enzymol. 2005;399:585-609
references.pmid: 16338383
references.citation: Biochem J. 2010 Sep 15;430(3):461-76
references.pmid: 20632995
references.citation: Int J Oncol. 2001 Dec;19(6):1211-20
references.pmid: 11713591
references.citation: PLoS One. 2010 Feb 18;5(2):e9287
references.pmid: 20174631
references.citation: J Neuroimmunol. 2003 Feb;135(1-2):135-40
references.pmid: 12576233
references.citation: Br J Haematol. 2011 Jan;152(2):155-63
references.pmid: 21114484
references.citation: Exp Eye Res. 2002 Sep;75(3):271-84
references.pmid: 12384090
references.citation: BMC Biochem. 2008 Oct 21;9 Suppl 1:S7
references.pmid: 19007437
references.citation: Neurobiol Aging. 2006 Jan;27(1):54-66
references.pmid: 16298241
references.citation: Curr Pharm Des. 2013;19(22):4140-51
references.pmid: 23181576
references.citation: Mol Biosyst. 2012 Sep;8(9):2295-302
references.pmid: 22722901
references.citation: Cancer Res. 2004 Sep 1;64(17):6319-26
references.pmid: 15342421
references.citation: Fiziol Zh. 2009;55(2):3-10
references.pmid: 19526842
references.citation: Clin Cancer Res. 2005 Apr 1;11(7):2552-60
references.pmid: 15814633
references.citation: Scand J Gastroenterol. 2009;44(8):960-9
references.pmid: 19492245
references.citation: Blood. 2012 Nov 29;120(23):4513-6
references.pmid: 23018640
references.citation: Exp Gerontol. 2002 Jan-Mar;37(2-3):301-8
references.pmid: 11772516
references.citation: Ann Rheum Dis. 1998 Jan;57(1):33-7
references.pmid: 9536820
references.citation: Kobe J Med Sci. 2006;52(3-4):85-95
references.pmid: 16855371
references.citation: Mol Urol. 2001 Autumn;5(3):113-9
references.pmid: 11690558
references.citation: Br J Cancer. 2012 Jun 26;107(1):53-62
references.pmid: 22677907
references.citation: J Rheumatol. 2000 Jan;27(1):183-9
references.pmid: 10648037
references.citation: Chem Biol. 2007 Apr;14(4):419-30
references.pmid: 17462577
references.citation: Clin Endocrinol (Oxf). 1999 Jul;51(1):115-8
references.pmid: 10468973
references.citation: Ageing Res Rev. 2003 Oct;2(4):419-32
references.pmid: 14522244
references.citation: EMBO J. 1994 Jul 15;13(14):3236-44
references.pmid: 8045254