Linking Global Youth Tobacco Survey (GYTS) data to the WHO Framework Convention on Tobacco Control (FCTC): the case for the Seychelles

Tobacco control has been recognized as a main public health concern in Seychelles for the past two decades. Tobacco advertising, sponsoring and promotion has been banned for years, tobacco products are submitted to high taxes, high-profile awareness programs are organized regularly, and several other control measures have been implemented. The Republic of Seychelles was the first country to ratify the WHO Framework Convention on Tobacco Control (FCTC) in the African region. Three population-based surveys have been conducted in adults in Seychelles and results showed a substantial decrease in the prevalence of smoking among adults between 1989 and 2004. A first survey in adolescents was conducted in Seychelles in 2002 (the Global Youth Tobacco Survey, GYTS) in a representative sample of 1321 girls and boys aged 13-15 years. The results show that approximately half of students had tried smoking and a quarter of both boys and girls had smoked at least one cigarette during the past 30 days. Although "current smoking" is defined differently in adolescents (>or=1 cigarette during the past 30 days) and in adults (>or=1 cigarette per day), which precludes direct comparison, the high smoking prevalence in youth in Seychelles likely predicts an increasing prevalence of tobacco use in the next adult generation, particularly in women. GYTS 2002 also provides important data on a wide range of specific individual and societal factors influencing tobacco use. Hence, GYTS can be a powerful tool for monitoring the situation of tobacco use in adolescents, for highlighting the need for new policy and programs, and for evaluating the impact of current and future programs.

The role of MMP-9 and its fibronectin-like domain in tumor growth & invasion : certainties, controversies & discrepancies

Tumors are often compared to wounds that do not heal, where the crosstalk between tumor cells and their surrounding stroma is crucial at all stages of development, from the initial primary growth to metastasis. Similar to wound healing, fibroblasts in the tumor stroma differentiate into myofibroblasts, also referred to as "cancer-associated fibroblasts" (CAFs), primarily, but not exclusively, in response to transforming growth factor-ß (TGF-ß). Myofibroblasts in turn enhance tumor progression by remodeling the stroma. Among molecules implicated in stroma remodeling, matrix metalloproteinases (MMPs), and MMP-g in particular, play a prominent role. However, the mechanisms that regulate MMP-g activation and function remain poorly understood. Recent evidence indicates that tumor cell surface association of MMP-g is an important event in its activation, and more generally in tumor growth and invasion. In the present work we address the potential association of MMP-g activity with cell-surface recruitment to human fibroblasts. We show for the first time that recruitment of MMP-g to the MRC-5 fibroblast cell surface occurs through the fibronectin-like (FN) domain, shared only by MMP-g and MMP-2 among all the MMPs. Functional assays suggest that both the pro- and active form of MMP-g trigger a-smooth muscle actin (aSMA) expression in resting fibroblasts that reflects myofibroblast differentiation, possibly through TGF-ß activation. Moreover, the FN domain of MMP-g inhibits both MMP-g-induced TGF-ß activation and aSMA expression by sequestering MMP-g. Xenograft experiments in NOD/SCID mice using HT1080 fibrosarcoma or MDA-MD231 breast adenocarcinoma cells stably expressing the FN domain of MMP-g revealed no changes in primary tumor growth. However, in the context of metastasis, expression of the FN domain by these same tumor cells dramatically increased their metastatic proclivity whereas expression of wt MMP-g either promoted no change or actually reduced the number of metastases. We observed a decrease of an active form of MMP-g in MDA-MB231 cells overexpressing the FN domain suggesting that the FN domain may inhibit MMP-g activity in Tumors are often compared to wounds that do not heal, where the crosstalk between tumor cells and their surrounding stroma is crucial at all stages of development, from the initial primary growth to metastasis. Similar to wound healing, fibroblasts in the tumor stroma differentiate into myofibroblasts, also referred to as "cancer-associated fibroblasts" (CAFs), primarily, but not exclusively, in response to transforming growth factor-ß (TGF-ß). Myofibroblasts in turn enhance tumor progression by remodeling the stroma. Among molecules implicated in stroma remodeling, matrix metalloproteinases (MMPs), and MMP-g in particular, play a prominent role. However, the mechanisms that regulate MMP-g activation and function remain poorly understood. Recent evidence indicates that tumor cell surface association of MMP-g is an important event in its activation, and more generally in tumor growth and invasion. In the present work we address the potential association of MMP-g activity with cell-surface recruitment to human fibroblasts. We show for the first time that recruitment of MMP-g to the MRC-5 fibroblast cell surface occurs through the fibronectin-like (FN) domain, shared only by MMP-g and MMP-2 among all the MMPs. Functional assays suggest that both the pro- and active form of MMP-g trigger a-smooth muscle actin (aSMA) expression in resting fibroblasts that reflects myofibroblast differentiation, possibly through TGF-ß activation. Moreover, the FN domain of MMP-g inhibits both MMP-g-induced TGF-ß activation and aSMA expression by sequestering MMP-g. Xenograft experiments in NOD/SCID mice using HT1080 fibrosarcoma or MDA-MD231 breast adenocarcinoma cells stably expressing the FN domain of MMP-9 revealed no changes in primary tumor growth. However, in the context of metastasis, expression of the FN domain by these same tumor cells dramatically increased their metastatic proclivity whereas expression of wt MMP-g either promoted no change or actually reduced the number of metastases. We observed a decrease of an active form of MMP-9 in MDA-MB231 cells overexpressing the FN domain suggesting that the FN domain may inhibit MMP-9 activity in those cells and therefore prevent MMP-9-induced activation of TGF-b, which results in increased invasion. Curiously, xenografts of SW480 colorectal adenocarcinoma cells stably expressing the FN domain of MMP-9 displayed reduced growth at both the primary (subcutaneous) injection site and the lungs of NOD/SCID mice, in experimental metastasis assays, whilst the same cells overexpressing wt MMP-9 showed enhanced growth and dissemination. Gelatin zymography of conditioned medium revealed that these effects may be due to the FN domain, which displaces MMP-9 from SW480 cell surface. These observations suggest a dual role of MMP-9 and its FN domain in primary tumor growth and metastasis, underscoring the notion that the effect of MMP-9 on tumor cells may depend on the cell type and highlighting possible protective effects of MMPs in tumor progression.