Probing non-enzymatic glycation of type I collagen: a novel approach using Raman and infrared biophotonic methods.

BACKGROUND: Non-enzymatic glycation is the main post-translational modification of long-life proteins observed during aging and physiopathological processes such as diabetes and atherosclerosis. Type I collagen, the major component in matrices and tissues, represents a key target of this spontaneous reaction which leads to changes in collagen biomechanical properties and by this way to tissue damages. METHODS: The current study was performed on in vitro glycated type I collagens using vibrational microspectroscopies, FT-IR and Raman, to highlight spectral features related to glycation effect. RESULTS AND CONCLUSIONS: We report a conservation of the triple-helical structure of type I collagen and noticeable variations in the exposure of proline upon glycation. Our data also show that the carbohydrate band can be a good spectroscopic marker of the glycation level, correlating well with the fluorescent AGEs formation with sugar addition. GENERAL SIGNIFICANCE: These non-invasive and label-free methods can shed new light on the spectral features of glycated collagens and represent an effective tool to study changes in the extracellular matrix observed in vivo during aging or on the advent of a pathological situation.

3D collagen type I matrix inhibits the antimigratory effect of doxorubicin.

BACKGROUND: The cell microenvironment, especially extracellular matrix proteins, plays an important role in tumor cell response to chemotherapeutic drugs. The present study was designed to investigate whether this microenvironment can influence the antimigratory effect of an anthracycline drug, doxorubicin, when tumor cells are grown in a matrix of type I collagen, a three-dimensional (3D) context which simulates a natural microenvironment. METHODS: To this purpose, we studied the migratory parameters, the integrin expression, and the activation state of focal adhesion kinase (FAK) and GTPase RhoA involved in the formation of focal adhesions and cell movement. These parameters were evaluated at non toxic concentrations which did not affect HT1080 cell proliferation. RESULTS: We show that while doxorubicin decreased cell migration properties by 70% in conventional two-dimensional (2D) culture, this effect was completely abolished in a 3D one. Regarding the impact of doxorubicin on the focal adhesion complexes, unlike in 2D systems, the data indicated that the drug neither affected beta1 integrin expression nor the state of phosphorylation of FAK and RhoA. CONCLUSION: This study suggests the lack of antiinvasive effect of doxorubicin in a 3D environment which is generally considered to better mimic the phenotypic behaviour of cells in vivo. Consistent with the previously shown resistance to the cytotoxic effect in a 3D context, our results highlight the importance of the matrix configuration on the tumor cell response to antiinvasive drugs.

Extracellular matrix proteins modulate antimigratory and apoptotic effects of Doxorubicin.

Anticancer drug resistance is a multifactorial process that includes acquired and de novo drug resistances. Acquired resistance develops during treatment, while de novo resistance is the primary way for tumor cells to escape chemotherapy. Tumor microenvironment has been recently shown to be one of the important factors contributing to de novo resistance and called environment-mediated drug resistance (EMDR). Two forms of EMDR have been described: soluble factor-mediated drug resistance (SFM-DR) and cell adhesion-mediated drug resistance (CAM-DR). Anthracyclines, among the most potent chemotherapeutic agents, are widely used in clinics against hematopoietic and solid tumors. Their main mechanism of action relies on the inhibition of topoisomerase I and/or II and the induction of apoptosis. Beyond this well-known antitumor activity, it has been recently demonstrated that anthracyclines may display potent anti-invasive effects when used at subtoxic concentrations. In this paper, we will describe two particular modes of EMDR by which microenvironment may influence tumor-cell response to one of these anthracyclines, doxorubicin. The first one considers the influence of type I collagen on the antimigratory effect of doxorubicin (CAM-DR). The second considers the protection of tumor cells by thrombospondin-I against doxorubicin-induced apoptosis (SFM-DR).

Impact of carbamylation and glycation of collagen type I on migration of HT1080 human fibrosarcoma cells.

Collagen type I is an abundant component of the extracellular matrix and due to its longevity, constitutes a prominent target of non-enzymatic post-translational in vivo modifications such as carbamylation and glycation. These protein modifications involved in aging, renal diseases and diabetes, are linked to elevated cancer risk. In this in vitro study, we investigated the impact of carbamylated and glycated collagen type I on the migratory behavior of the highly invasive HT1080 human fibrosarcoma cells. The proliferation of HT1080 on modified collagens did not differ from that on native form. The glycated collagen delayed the cell adhesion time whereas the carbamylated one had no effect. The migration ability of HT1080 was studied by quantifying single cell speed using videomicroscopy. Glycation strongly inhibited mean cell speed by 47% whereas carbamylation moderately affected it by 12%. In addition, the influence of these collagen modifications on actin and vinculin organization was studied. On the glycated collagen, 63% of cells revealed a dramatic loss of actin stress fibers vs. 28% on the carbamylated one. In these cells, disorganized F-actin was accompanied with a disturbance of vinculin and both proteins were localized at the rim of the cells. Concerning the focal adhesion kinase (FAK) expression, glycated collagen only induced a significant inhibition. Whereas, both collagen modifications provoked a differential inhibition of FAK phosphorylation state by 25% for carbamylation and 60% for glycation. In conclusion, our data suggest that, in vivo, collagen glycation and carbamylation may affect tumor cell metastasis. This suggestion is supported by clinical studies reporting less aggressive tumors in diabetic or uremic patients. Consequently, the impact of such post-translational modifications has to be taken into account in order to better understand the link between aging, diabetes or uremia and cancer progression.