The LIM-only protein, LMO4, and the LIM domain-binding protein, LDB1, expression in squamous cell carcinomas of the oral cavity.
Carcinoma cells can lose their epithelial cell characteristics and dedifferentiate into a fibroblast-like cell during progression of a neoplasm. Aberrant expression of oligomeric transcriptional complexes contributes to progression of carcinomas. Although individual transcription factors initiating progression remain unknown, LIM-only protein (LMO) and LIM-domain binding protein (LDB) negatively regulate breast carcinoma cell differentiation. In this study, we investigated the expression of LMO4 and LDB in squamous cell carcinomas of the oral cavity. LMO4 mRNA was amplified in four of six carcinoma tissues and eight of 12 carcinoma cell lines, and LDB1 in three carcinoma tissues and 11 cell lines examined. Immunoprecipitation studies revealed that LMO4 and LDB1 interact with each other in the nuclear milieu of the carcinoma cells indicating the presence of an LMO4-LDB1-mediated transcription complex. Both LMO4 and LDB1 proteins were preferentially localised in the nuclei of carcinoma cells at the invasive front and the immunoreactivity was increased in less-differentiated carcinoma tissues (P<0.01). Carcinoma cells metastasised to the cervical lymph nodes with increased immunoreactivity compared to the primary site of neoplasm (P<0.05). These data suggest that the LMO4-LDB1 complexes may be involved in carcinoma progression possibly through dedifferentiation of squamous carcinoma cells of the oral cavity.
Mizunuma
H
H
Department of Biochemistry, School of Dentistry, Nippon Dental University, 1-9-20 Fujimi, Chiyoda-ku, Tokyo 102-8159, Japan.
Miyazawa
J
J
Sanada
K
K
Imai
K
K
D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000473:pathology*; D002454:Cell Differentiation; D002467:Cell Nucleus; D002471:Cell Transformation, Neoplastic; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000032:analysis / Q000494:pharmacology*; D018450:Disease Progression; D006801:Humans; D060588:LIM Domain Proteins; D009062:Mouth Neoplasms / Q000235:genetics / Q000473:pathology*; D009362:Neoplasm Metastasis; D015513:Oncogene Proteins / Q000032:analysis / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D014157:Transcription Factors; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D004268:DNA-Binding Proteins; C486312:LDB1 protein, human; D060588:LIM Domain Proteins; D015513:Oncogene Proteins; D014157:Transcription Factors