Evaluation of the Interaction Between TGF β and Nitric Oxide in the Mechanisms of Progression of Colon Carcinoma

Abstract

It is recognised that stromal cells determine cancer progression. We have previously shown that active TGFbeta produced by rat colon carcinoma cells modulated NO production in rat endothelial cells. To elucidate the role of TGFbeta and NO in the mechanisms of interaction of colon carcinoma cells with stromal cells and in cancer progression, we transfected REGb cells, a regressive colon carcinoma clone secreting latent TGFbeta, with a cDNA encoding for a constitutively-secreted active TGFbeta. Out of 20 injected rats only one tumour progressed, which was resected and sub-cultured (ReBeta cells). ReBeta cells secreted high levels of active TGFbeta. The adhesive properties of REGb and Rebeta cells to endothelial cells were similar, showing that the secretion of active TGFbeta is not involved in tumour cell adhesion to endothelial cells. ReBeta, but not REGb, cell culture supernatants inhibited cytokine-dependent NO secretion by endothelial cells, but inhibition of NO production was similar in co-cultures of REGb or ReBeta cells with endothelial cells. Therefore, secretion of active TGFbeta regulated endothelial NO synthase activity when tumour cells were distant from, but not in direct contact with, endothelial cells. However, only ReBeta cells inhibited cytokine-dependent secretion of NO in coculture with macrophages, indicating that the active-TGFbeta-NO axis confers an advantage for tumour cells in their interaction with macrophages rather than endothelial cells in cancer progression.

Chitosan-based nanogels for selective delivery of photosensitizers to macrophages and improved retention in and therapy of articular joints

“…In order to determine whether exposure to these PS-nanogels may result in macrophage activation, the production of nitric oxide (NO) production, a very sensitive marker of activation of rodent macrophages [33], was determined. To control for RAW 264.7 macrophage responsiveness to activation, cells were exposed to γIFN and TNF-α [33].…”

“…To control for RAW 264.7 macrophage responsiveness to activation, cells were exposed to γIFN and TNF-α [33]. Macrophage secretion of NO was evaluated after 24 h cell exposure to any of the three PS-nanogels (17%).…”

“…As no significant differences in the uptake of the three PS-nanogels by macrophages were observed, these results are compatible with the known hierarchy of intrinsic photodynamic efficiencies of the three photosensitizers. It has to be noted that light doses of 1-15 J/cm 2 and up to 48 J/cm 2 are generally used in most photodynamic therapy protocols [33,34,[40][41][42][43].…”

“…Cell NO production was determined as nitrite accumulation in cell culture media using the Griess microassay, as previously described [33]. Briefly, 100 µL of cell supernatants was added to 100 µL of Griess reagent (0.5% w/w sulfanilamide and 0.05% w/w naphthylethylenediamine in 2.5% w/w phosphoric acid).…”

TGF-β1 influence on TNF-α production and sTNF-Rs shedding in a coculture of colon carcinoma cell spheroids with normal cells

“…TGF-β is a multifunctional polypeptide abundantly expressed in many epithelial tumors and involved in the mechanisms regulating tumor progression (Bates and Mercurio 2003;Lohm et al 2005). Currently, it is well known that TGF-β, depending on the stage of tumorigenesis, acts as both a tumor suppressor and a stimulator of tumor progression and metastasis.…”