trisialoganglioside-gt1 and Skin-Neoplasms

The interaction of the urokinase-type plasminogen activator (uPA) receptor (uPAR) with integrins plays a critical role in the regulation of cell adhesion and migration. However, the molecular events underlying the modulation of the interaction of uPAR and integrin are poorly understood. Gangliosides are thought to regulate epithelial cell adhesion and migration by inhibiting alpha(5)beta(1) integrin and epidermal growth factor receptor (EGFR) signaling. We report here that increases in the expression of ganglioside NeuAcalpha2-->3Galbeta1-->3GalNAcbeta1-->4(NeuAcalpha2-->8NeuAcalpha2-->3)Galbeta1-->4Glcbeta1-Cer (GT1b) or NeuAcalpha2-->3Galbeta1-->4Glcbeta1-Cer (GM3) inhibit uPA-dependent cell migration by preventing the association of uPAR with alpha(5)beta(1) integrin or uPAR/alpha(5)beta(1) integrin with the EGFR, respectively. As a result, uPA-dependent focal adhesion kinase (FAK) and integrin-mediated EGFR signaling are suppressed. Both gangliosides inhibit uPAR signaling-stimulated migration; however, GM3 inhibits uPA-induced EGFR phosphorylation by blocking the crosstalk between integrin and EGFR, whereas GT1b suppresses both uPA-induced FAK and EGFR activation by preventing the activation of integrin alpha(5)beta(1).

Topics: Carcinoma, Squamous Cell; Cell Line; Cell Movement; ErbB Receptors; Focal Adhesion Kinase 1; Focal Adhesion Protein-Tyrosine Kinases; G(M3) Ganglioside; Gangliosides; Humans; Integrin alpha5beta1; Keratinocytes; Oligodeoxyribonucleotides, Antisense; Phosphorylation; Protein-Tyrosine Kinases; Receptors, Cell Surface; Receptors, Urokinase Plasminogen Activator; Skin Neoplasms

We studied the effects of various gangliosides on in vitro growth of human metastatic melanoma WM266-4. GD1b, GT1b, and GQ1b inhibited 3H-thymidine uptake and growth rate of WM266-4 whereas the other gangliosides were ineffective. The growth inhibition by GD1b, GT1b, and GQ1b was counteracted by interleukin-8 but not by the other growth factors. The growth inhibition by gangliosides was not detected in the presence of anti-interleukin-8 antibody. GD1b, GT1b, and GQ1b reduced the constitutive interleukin-8 secretion and mRNA levels in WM266-4. Transient transfection showed that GD1b, GT1b, and GQ1b inhibited the constitutive chloramphenicol acetyltransferase expression driven by interleukin-8 promoter in WM266-4. Transfection with a series of 5'-deleted mutants demonstrated that the sequences between -98 and -62 bp on interleukin-8 promoter may be involved in the transcriptional repression by these gangliosides. Cyclic AMP analog dibutyryl cAMP counteracted GD1b, GT1b, and GQ1b-induced inhibition of interleukin-8 production at the levels of protein secretion, mRNA expression, and promoter activity. GD1b, GT1b, and GQ1b reduced cAMP level and protein kinase A activity in WM266-4. These gangliosides suppressed adenylate cyclase activity without altering that of cyclic nucleotide phosphodiesterase in WM266-4. The data indicate that GD1b, GT1b, and GQ1b may suppress the growth of melanoma by inhibiting interleukin-8 production via the inhibition of adenylate cyclase.

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Adenylyl Cyclase Inhibitors; Cell Division; Chloramphenicol O-Acetyltransferase; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Dose-Response Relationship, Drug; Female; Gangliosides; Gene Expression Regulation, Neoplastic; Humans; Interleukin-8; Melanoma; Promoter Regions, Genetic; RNA, Messenger; Skin Neoplasms; Transcription, Genetic; Tumor Cells, Cultured

A 52-year-old Japanese woman developed numerous amelanotic metastatic melanomas on the skin and in various organs three years after a surgical operation for primary melanoma on the right axilla. The patient was treated with monosialoganglioside specific monoclonal antibody 202; however, no apparent clinical effects were observed. Ganglioside analysis of a metastatic tumor demonstrated that it expressed GM3, GM2, GD3, GD2, and polysialogangliosides. Since polysialogangliosides rarely appear in melanomas, their expression may explain the patient's poor response to MAb 202. The relationship between ganglioside composition and the effect of anti-ganglioside monoclonal antibody is discussed.

Topics: Antibodies, Monoclonal; Female; Gangliosides; Humans; Melanoma, Amelanotic; Middle Aged; Skin Neoplasms

Benzoyl peroxide (BzPo), a free radical generator with tumor promoting activity on mouse skin, is shown to promote neoplastic transformation of JB6 mouse epidermal cells in vitro. Repeated exposures to BzPo are required to readily detect promotion of transformation of JB6 cells. Markedly reduced net synthesis of the major epidermal ganglioside, trisialoganglioside GT1b, (GT) occurs with BzPo treatment as with other tumor promoters active in this system. Addition of ganglioside GT prevents transformation by BzPo while retinoic acid does not.

Topics: Animals; Benzoyl Peroxide; Cell Line; Cell Transformation, Neoplastic; Cocarcinogenesis; Gangliosides; Mice; Peroxides; Skin Neoplasms; Tetradecanoylphorbol Acetate; Tretinoin