Genomic structure of human OKL38 gene and its differential expression in kidney carcinogenesis.
We previously demonstrated the growth inhibitory property of OKL38 and its possible roles in mammary carcinogenesis. To further understand the regulation and roles of OKL38 in tumorigenesis we proceeded to clone and characterize the human OKL38 gene and three of its variants with transcripts of 1.9, 2.2, and 2.4 kb. The human OKL38 gene spans approximately 18 kb and contains 8 exons and 7 introns with exon size ranging from 92 to 1270 bp. RT-PCR and sequence analysis suggest that different transcripts were arrived through differential promoter usage and alternate splicing. Multiple Tissue Expression array (MTE) and Multiple Tissue Northern blot (MTN) indicated that OKL38 was ubiquitously expressed in all tissues with high expression in liver, kidney, and testis. The cancer profiling array (CPA) of paired normal/tumor cDNA showed that OKL38 mRNA was down-regulated in 70% (14 of 20) of kidney tumors. Western analysis revealed that the OKL38 protein was undetectable in 78% (7 of 9 pairs) of kidney tumor tissues. Immunohistological analysis showed that 64% (14 of 22) of kidney tumors were either lost or underexpressed OKL38 protein compared with the adjacent normal tissue. A transfection study using OKL38-eGFP recombinant construct showed that overexpression of the 52 kDa OKL38 protein in A498 cells resulted in growth inhibition and cell death. This study demonstrates the complex genomic structure of the OKL38 gene and its growth inhibitory and cytotoxic properties. Our data suggest the potential use of OKL38 in diagnosis, prognosis, and/or treatment of kidney cancer.
Laboratory of Molecular Endocrinology, Division of Cellular and Molecular Research, National Cancer Center, Singapore 169610.
Choon Kiat
CK
Ong
Chuan Young
CY
Ng
Caine
C
Leong
Chee Pang
CP
Ng
Keong Tatt
KT
Foo
Puay Hoon
PH
Tan
Hung
H
Huynh
D051017:Apoptosis Regulatory Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D014644:Genetic Variation; D015894:Genome, Human; D006131:Growth Inhibitors / Q000235:genetics*; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics*; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D011506:Proteins; D015183:Restriction Mapping; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic
D051017:Apoptosis Regulatory Proteins; D017931:DNA Primers; D006131:Growth Inhibitors; C432368:OSGIN1 protein, human; D011506:Proteins