Leukocyte common-antigen-related tyrosine phosphatase receptor: altered expression of mRNA and protein in the New England Deaconess Hospital rat line exhibiting spontaneous pheochromocytoma.
Regulation of cell proliferation by protein tyrosine phosphatases (PTPs) suggests that PTPs are important tumor suppressor genes. The gene encoding the leukocyte common-antigen-related (LAR) PTP receptor maps to chromosome 1p32-33, a region in which loss of heterozygosity is associated with human pheochromocytoma and other neuroectodermal tumors. The rat pheochromocytoma PC12 cell line was originally derived from the transplantable P259 tumor originating from the New England Deaconess Hospital (NEDH) line of Wistar inbred rats. Compared with their Wistar counterparts, 1-2-year-old NEDH rats exhibit a high incidence of spontaneous pheochromocytomas. This study investigates whether levels of LAR transcripts and protein are altered in NEDH adrenal tissue prior to tumor onset. In addition, alternative splicing of an LAR extracellular domain [LAR alternatively spliced element-c (LASE-c)], regulating LAR interaction with extracellular matrix components, was examined. These changes in LAR expression and alternative splicing were hypothesized to be more pronounced in tumor tissue and PC12 cells. Northern blot analysis demonstrated the presence of the approximately 5 kb LAR transcript in all cell lines examined, except PC12. In adrenal medulla tissue harvested from 2-3-month-old rats, LAR approximately 8 and approximately 5 kb transcript expression was decreased in NEDH compared with Wistar samples. RT-PCR demonstrated increased splicing of the LASE-c 27 bp alternatively spliced insert in the LAR extracellular domain in NEDH adrenal medulla tissue. Even greater LASE-c splicing was detected in adrenal medulla tumor tissue derived from 12-month-old NEDH rats and in PC12 cells. Western blot analysis demonstrated decreased levels of LAR protein and increased levels of LASE-c containing LAR protein isoforms in NEDH adrenal medulla tissue. These studies demonstrate that patterns of altered LAR expression present in PC12 cells and in pheochromocytoma tumor tissue are also present in adrenal tissue predisposed to a high incidence of spontaneous pheochromocytoma.
Yang
T
T
Department of Neurology, University of California San Francisco/VA Medical Center, San Francisco, CA 94121, USA.
Martignetti
J A
JA
Massa
S M
SM
Longo
F M
FM
D000302:Adrenal Cortex / Q000201:enzymology; D000310:Adrenal Gland Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D000313:Adrenal Medulla / Q000201:enzymology; D017398:Alternative Splicing; D000818:Animals; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D004790:Enzyme Induction; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics*; D009386:Neoplastic Syndromes, Hereditary / Q000201:enzymology / Q000235:genetics; D009419:Nerve Tissue Proteins; D016716:PC12 Cells; D010673:Pheochromocytoma / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics*; D017027:Protein Tyrosine Phosphatases; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar / Q000235:genetics*; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2; D011956:Receptors, Cell Surface / Q000096:biosynthesis / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013045:Species Specificity
D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; C516772:PTPRF protein, human; D017027:Protein Tyrosine Phosphatases; C516774:Ptprf protein, rat; D054623:Receptor-Like Protein Tyrosine Phosphatases, Class 2