Structural characteristics of the 5' region of the human ICAM-1 gene.

The ICAM-1 glycoprotein, one of the major cellular adhesion molecules, exhibits a diverse and highly regulated tissue distribution. To better understand the regulatory mechanisms underlying its particular expression pattern, we have cloned the ICAM-1 gene from human leukocyte libraries. By hybridization with various DNA probes derived from different regions of the ICAM-1 cDNA, several clones were identified and isolated. Clone HWB 3R1, containing a 15kb DNA insert, was selected for further characterization. The HWB 3R1 clone hybridized with probes corresponding to the 3' as well as the 5' region of the ICAM-1 cDNA and gave rise to ICAM-1 expression after transfection into the ICAM-1 deficient MJP17 melanoma cell line. The identity of the expressed ICAM-1 was verified by reaction with five different monoclonal antibodies specific for ICAM-1. Sequence analysis of about 1.2kb of DNA around the ATG start codon revealed putative binding sites for various transcription factors situated in the 5' untranslated region as well as within the first intron. These include SP-1, AP-1 and NF-kB binding sites as well as interferon and retinoic acid responsive elements.

The melanoma progression-associated antigen P3.58 is identical to the intercellular adhesion molecule, ICAM-1.

The 89kd cell surface glycoprotein, P3.58, is expressed on human malignant melanomas in situ where it is associated with an increased risk of metastatic disease. Monoclonal antibodies detecting denatured P3.58 were produced and used to isolate a P3.58 encoding cDNA clone from a human melanoma lambda expression library. Sequencing of the cDNA revealed that the P3.58 antigen is identical to the leukocyte intercellular adhesion molecule 1 (ICAM-1).

De novo expression of intercellular-adhesion molecule 1 in melanoma correlates with increased risk of metastasis.

The 89-kDa cell surface glycoprotein, P3.58, is detectable on advanced human melanomas in situ but not on benign melanocytes or early melanomas. cDNA cloning of P3.58 from melanoma cells was accomplished by screening a lambda zap expression vector library with monoclonal antibodies produced against the denatured antigen. Nucleotide sequencing of the clones revealed that P3.58 is identical to the intercellular-adhesion molecule 1. No qualitative differences in P3.58 mRNA species could be seen between melanoma cells and hematopoietic cells and no differences in gene organization were observed between peripheral blood leukocytes and melanoma cells. Inspection of the deduced amino acid sequence of P3.58 indicated the presence of the consensus sequence characteristic for complement-binding proteins. The acquisition of this cell-adhesion molecule during the process of tumor progression is speculated to contribute to the development of metastasis in melanoma.

Functional aspects of three molecules associated with metastasis development in human malignant melanoma.

To identify molecules which may be functionally associated with the development of metastasis in human melanoma, monoclonal antibodies which discriminate between benign and malignant melanocytic lesions in situ were selected. Biochemical studies and cDNA cloning identified the antigens HLA-DR, ICAM-1 and MUC18 which showed an expression pattern on primary tumors correlating with vertical tumor thickness, the most predictive parameter for the development of metastasis in melanoma. ICAM-1 and MUC18 show sequence similarity to a family of cell adhesion molecules which include the neural cell adhesion molecule NCAM. Both HLA-DR and ICAM-1 can be induced on melanoma cells by lymphokines, suggesting a role of the mononuclear cell infiltrate in the control of tumor cell phenotype. Knowledge of the normal function of these molecules allows one to hypothesize how they may contribute to the successful development of metastases.

12-O-tetradecanoylphorbol-13-acetate- and tumor necrosis factor alpha-mediated induction of intercellular adhesion molecule-1 is inhibited by dexamethasone. Functional analysis of the human intercellular adhesion molecular-1 promoter.

Transcription regulation of the human intercellular adhesion molecule-1 gene by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), tumor necrosis factor alpha (TNF alpha), and the glucocorticoid dexamethasone was studied using transient transfections in 293 cells with intercellular adhesion molecule-1 promoter-luciferase constructs (together with a glucocorticoid receptor expression vector). TPA and TNF alpha induced promoter activity, which was repressed by dexamethasone. Four TPA-responsive DNA regions were identified, each containing a potential TPA-responsive enhancer sequence: 1) -677/-340 an AP3-like sequence; 2) -290/278 a TPA-response element (TRE); 3) -227/-175 an NF kappa B-like sequence; 4) -105/-38 an AP2-like sequence. TNF alpha enhanced transcription only through region 3. The TRE in region 2 appeared to be functionally coupled to a distal TATA box at -313 and differed from the consensus TRE with respect to binding characteristics for members of the AP1 family. The newly identified NF kappa B enhancer (TGGAAATTCC) is bound by a TNF alpha-induced nuclear protein and appears to be the key element in rapid transcription induction by TNF alpha (and TPA), while transactivation of this element is repressed by the ligand-bound glucocorticoid receptor. We propose a negative cross-talk between the NF kappa B transcription factor and the glucocorticoid receptor.