NHERF (Na+/H+ exchanger regulatory factor) gene mutations in human breast cancer.
Yeast two-hybrid screening was used to explore novel proteins that interact with a breast tumor or metastasis suppressor, SYK (spleen tyrosine kinase). The screening yielded NHERF (Na+/H+ exchanger regulatory factor, also known as NHERF1 or EBP-50) that binds to the interdomain B of SYK. NHERF is an estrogen-responsive gene that encodes an inhibitory factor for epithelial Na+/H+ exchanger isoform 3 (NHE3). We found intragenic mutation of the NHERF gene accompanied by loss of heterzygosity (LOH) in approximately 3% (3/85) of breast cancer cell lines and primary breast tumors. Mutations occurred at the conserved PDZ domains at NHERF NH2-terminus that bound to SYK, or at its COOH-terminus motif that binds to MERLIN, the product of Neurofibromatosis 2 (NF2) tumor suppressor gene. NHERF tumorigenic mutations decreased or abolished its interaction with SYK or MERLIN, suggesting a pathway link among these three molecules that may play a critical role in mammary neoplastic progression. Primary breast tumors with LOH at the NHERF locus had clinical presentations of higher aggressiveness, indicating that deregulated NHERF signaling may be associated with disease progression. Moreover, the LOH was inversely correlated with SYK promoter methylation, suggesting that NHERF and SYK may transduce a common suppressive signal. Taken together, the results indicated NHERF to be a candidate tumor suppressor gene in human breast carcinoma that may be interconnected to the SYK and MERLIN suppressors.
Department of Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. jldai@mdanderson.org
Jia Le
JL
Dai
Lei
L
Wang
Aysegul A
AA
Sahin
Lyle D
LD
Broemeling
Mieke
M
Schutte
Yong
Y
Pan
D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D017124:Conserved Sequence / Q000235:genetics; D018450:Disease Progression; D004792:Enzyme Precursors / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D019656:Loss of Heterozygosity / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D025581:Neurofibromin 2 / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers; D000072377:Syk Kinase; D014407:Tumor Cells, Cultured
D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D025581:Neurofibromin 2; D010750:Phosphoproteins; D017923:Sodium-Hydrogen Exchangers; C093376:sodium-hydrogen exchanger regulatory factor; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase