Tumor progression and metastasis represent the leading causes of cancer related death. One of the majorfeatures that may contribute to neoplastic cell dissemination is the progressive and local degradation of theextracellular matrix (ECM) surrounding the primary tumour. Degradation of the ECM requires the coordinatedaction of a number of enzymes produced locally by neoplastic cells and/or stromal cells. Five categories ofproteinases have been implicated in the invasive process: serine, cysteine, aspartic, threonine proteinases and matrixmetalloproteinases (MMPs), also known as matrixins, which play a key role as terminal effectors of the proteolyticcascade.At present 23 members of the matrixin family have been found in humans and classified into subsets ofenzymes, according to their molecular domains and preference for the substrates. Since the classic work of Liottaand collaborators , much attention has been focused on MMP-2 and MMP-9 because of their ability to degradetype IV collagen, a major constituent of basement membranes. MMP-9 and MMP-2 are secreted by cells aszymogens; both enzymes are activated, by the cleavage of their amino-terminal pro-domains, through distinctpathways operating at the cell-matrix boundary . Tissue detection of MMPs has suggested that augmentedsecretion and proteolytic activation of MMPs is often associatedwith tumor metastasis. Several authors have also detectedincremented levels of circulating forms MMP-2 and MMP-9 inoncologic patients [3-6]. However, their clinical applications remaincontroversial. To confirm and extend our previous observations, inthis study we analyzed the circulating forms of MMP-9 and MMP-2in serum samples of 56 selected breast carcinoma patients, incomparison with the enzymatic activities present in tissue extractsfrom surgical fragments (primary tumor and its paired healthytissues) of same patients. The activity levels of MMP-2 and MMP-9were detected by gelatin zymography and quantified byImageQuant TL. Two bands of activity, corresponding to theproforms of MMP-9 and MMP-2, were detected in the serumsamples and tissue extracts of all oncologic patients, but with highlyvariable levels of intensity. In general the intensity of lytic bandswas higher in serum than in the tissue extracts. In addition, mostserum samples, and some of the tissue extracts, displayed additionalproteolytic bands at higher Mw, corresponding likely to complexedforms of MMP-9 . As previously reported for a pilot number ofcases, lytic bands corresponding the activated forms of the twogelatinases were uniquely present in the tumor extracts, and absentin the paired normal tissues, thus confirming the hypothesis that activation of the enzymes is a key step during theinvasive growth of the tumor.In order to assess the possible association between MMPs activities and other proteins potentially involved intumor progression, we correlated the activity levels of both MMPs with the proteomic-based expression levels of theS100 protein members. One of the reasons of interest for this family of proteins is because there is increasingevidence that S100 proteins are often up-regulated in many cancers, including breast cancer, and this is frequentlyassociated with tumour progression.Interestingly we have observed a correlation between the gelatinase activity levels and expression levels ofsome S100 proteins.In conclusion, our results, which show higher variability of MMP-9 levels suggest its usefulness as a markerevaluable both in the follow-up and in the prognosis of breast cancer patients.
|Number of pages||1|
|Publication status||Published - 2010|