Proteomic analysis of a melanoma cell line: insight into a molecular pathway of tumorigenesis.

SOSA, MARIA SOLEDAD; LOPEZ, JUAN ANTONIO; CAMAFEITA, EMILIO; JUAREZ, SILVIA; ALBAR, JUAN PABLO; PODHAJCER, OSVALDO; LLERA, ANDREA S; ANDREA SABINA LLERA

Bariloche, Argentina

Congreso; Reunión Anual de la Sociedad Argentina de Investigaciones Bioquímicas39San Carlos de BarilocheArgentina; 2003

<!-- /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:1; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; font-size:10.0pt; mso-ansi-font-size:10.0pt; mso-bidi-font-size:10.0pt;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> SPARC is a matricellular glycoprotein that elicits changes in cell shape and proliferation. While its normal expression is restricted to tissues under remodeling, SPARC was found to be overexpressed in different tumors, in association with tumor progression and metastasis. Our previous results showed that stable antisense SPARC expression abolished tumorigenicity in an in vivo melanoma murine model. Traditional approaches to define a molecular pathway for SPARC-mediated tumor progression have failed to render meaningful results. Thus, we started a proteomic analysis of proteins expressed by melanoma cells with modulated SPARC expression, in order to identify new SPARC-interacting proteins. We studied conditioned culture medium from human MEL-LES clone 1-D (L-1D, showing an 80% decrease of SPARC mRNA and protein expression), as compared with the control MEL-LES clone CMV (L-CMV). Proteomic analysis was done by two-dimensional electrophoresis followed by tryptic digestion of spots and MALDI-TOF peptide fingerprinting analysis. Up to date we have identified 94 proteins, among them those related with SPARC function, as well as extracellular matrix structural proteins and oncoproteins. We are currently focusing in establishing which proteins are differentially expressed in the non-tumorigenic clone L-1D, as opposed to the tumorigenic clone L-CMV, aiming at identifying proteins that may be involved in SPARC molecular pathway.