Functional polymorphism of the CK2alpha intronless gene plays oncogenic roles in lung cancer.
Protein kinase CK2 is frequently up-regulated in human cancers, although the mechanism of CK2 activation in cancer remains unknown. In this study, we investigated the role of the CK2alpha intronless gene (CSNK2A1P, a presumed CK2alpha pseudogene) in the pathogenesis of human cancers. We found evidence of amplification and over-expression of the CSNK2A1P gene in non-small cell lung cancer and leukemia cell lines and 25% of the lung cancer tissues studied. The mRNA expression levels correlated with the copy numbers of the CSNK2A1P gene. We also identified a novel polymorphic variant (398T/C, I133T) of the CSNK2A1P gene and showed that the 398T allele is selectively amplified over the 398C allele in 101 non-small cell lung cancer tissue samples compared to those in 48 normal controls (p = 0.013<0.05). We show for the first time CSNK2A1P protein expression in transfected human embryonic kidney 293T and mouse embryonic fibroblast NIH-3T3 cell lines. Both alleles are transforming in these cell lines, and the 398T allele appears to be more transforming than the 398C allele. Moreover, the 398T allele degrades PML tumor suppressor protein more efficiently than the 398C allele and shows a relatively stronger binding to PML. Knockdown of the CSNK2A1P gene expression with specific siRNA increased the PML protein level in lung cancer cells. We report, for the first time, that the CSNK2A1P gene is a functional proto-oncogene in human cancers and its functional polymorphism appears to degrade PML differentially in cancer cells. These results are consistent with an important role for the 398T allele of the CSNK2A1P in human lung cancer susceptibility.
Hung
Ming-Szu
MS
Thoracic Oncology Laboratory, Department of Surgery, Comprehensive Cancer Center, University of California San Francisco, San Francisco, California, United States of America.
Lin
Yu-Ching
YC
Mao
Jian-Hua
JH
Kim
Il-Jin
IJ
Xu
Zhidong
Z
Yang
Cheng-Ta
CT
Jablons
David M
DM
You
Liang
L
D000818:Animals; D015153:Blotting, Western; D047390:Casein Kinase II / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics / Q000502:physiology; D006801:Humans; D047468:Immunoprecipitation; D017404:In Situ Hybridization, Fluorescence; D066298:In Vitro Techniques; D008175:Lung Neoplasms / Q000235:genetics*; D051379:Mice; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011110:Polymorphism, Genetic / Q000235:genetics / Q000502:physiology*; D000071156:Promyelocytic Leukemia Protein; D011485:Protein Binding; D000090063:Proto-Oncogene Mas; D034741:RNA, Small Interfering / Q000235:genetics / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
C000715470:MAS1 protein, human; D009687:Nuclear Proteins; D000071156:Promyelocytic Leukemia Protein; D000090063:Proto-Oncogene Mas; D034741:RNA, Small Interfering; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human; D047390:Casein Kinase II