Reduced expression and novel splice variants of ING4 in human gastric adenocarcinoma.
ING4, a new member of the ING (inhibitor of growth) family of tumour suppressor genes, has been found to be deleted or down-regulated in gliomas, breast tumours, and head and neck squamous cell carcinomas. The goal of the present study was to investigate whether the expression and alternative splicing of ING4 transcripts are involved in the initiation and progression of stomach adenocarcinoma. ING4 mRNA and protein expression was examined in gastric adenocarcinoma tissues and human gastric adenocarcinoma cell lines by RT-PCR, real-time RT-PCR, tissue microarray immunohistochemistry, and western blot analysis. Alterations in ING4 transcripts were determined through sequence analysis of ING4 cDNA. Our data showed that ING4 mRNA and protein were dramatically reduced in stomach adenocarcinoma cell lines and tissues, and significantly less in female than in male patients. We also found that reduced ING4 mRNA expression correlated with the stage of the tumour. Interestingly, by sequence analysis, we discovered five novel aberrantly spliced variant forms of ING4_v1 and ING4_v2. These variants cause a codon frame-shift and, eventually, deletion of the NLS or PHD domain contributing to the mislocalization of p53 and/or HAT/HDAC complexes and, subsequently, altered gene expression in gastric adenocarcinoma. These results suggest that attenuated and aberrant ING4 expression may be involved in the initiation and progression of stomach adenocarcinoma.
Li
Ming
M
Laboratory of Medical Genetics, Harbin Medical University, Harbin, China.
Jin
Yan
Y
Sun
Wen-jing
WJ
Yu
Yang
Y
Bai
Jing
J
Tong
Dan-dan
DD
Qi
Ji-ping
JP
Du
Jin-rong
JR
Geng
Jing-shu
JS
Huang
Qi
Q
Huang
Xiao-yi
XY
Huang
Yun
Y
Han
Fei-fei
FF
Meng
Xiang-ning
XN
Rosales
Jesusa L
JL
Lee
Ki-Young
KY
Fu
Song-bin
SB
D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000032:analysis / Q000235:genetics*; D045744:Cell Line, Tumor; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D018398:Homeodomain Proteins / Q000032:analysis / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000032:analysis / Q000235:genetics*
D018797:Cell Cycle Proteins; D018398:Homeodomain Proteins; C483230:ING4 protein, human; D012333:RNA, Messenger; D025521:Tumor Suppressor Proteins