ABSTRACT
Curcumin has shown some promise in the prevention of oral carcinogenesis by mechanism(s) that are still not completely resolved. Messenger RNA translation is mediated in eukaryotes by the eIF4F complex composed of eukaryotic translation initiation factors eIF4E, eIF4G, and eIF4A. Overexpression of some of these components or the inactivation of initiation repressor proteins (4E-BP1) has been implicated in cancer development including oral carcinogenesis by affecting cell survival, angiogenesis, and tumor growth and invasion. In this study, we examined the possibility that curcumin affects the translational machinery differently in normal, immortalized normal, leukoplakia, and malignant cells. Curcumin treatment in vitro inhibited the growth of immortalized oral mucosa epithelial cells (NOM9-CT) and the leukoplakia cells (MSK-Leuk1s) as well as in the UMSCC22B and SCC4 cells derived from head and neck squamous cell carcinoma. Curcumin only exerted minor effects on the growth of normal oral epithelial cells (NOM9). In the immortalized, leukoplakia, and cancer cells, curcumin inhibited cap-dependent translation by suppressing the phosphorylation of 4E-BP1, eIF4G, eIF4B, and Mnk1, and also reduced the total levels of eIF4E and Mnk1. Our findings show that immortalized normal, leukoplakia, and malignant oral cells are more sensitive to curcumin and show greater modulation of protein translation machinery than the normal oral cells, indicating that targeting this process may be an important approach to chemoprevention in general and for curcumin in particular.
Subject(s)
Antineoplastic Agents/pharmacology , Cell Line, Transformed/drug effects , Curcumin/pharmacology , Mouth Mucosa/drug effects , Peptide Chain Initiation, Translational/drug effects , Precancerous Conditions/drug therapy , Adaptor Proteins, Signal Transducing/antagonists & inhibitors , Adaptor Proteins, Signal Transducing/metabolism , Blotting, Western , Cell Cycle Proteins , Cell Line, Transformed/cytology , Cell Proliferation/drug effects , Cells, Cultured , Eukaryotic Initiation Factor-4G/antagonists & inhibitors , Eukaryotic Initiation Factor-4G/metabolism , Eukaryotic Initiation Factors/antagonists & inhibitors , Eukaryotic Initiation Factors/metabolism , Humans , Intracellular Signaling Peptides and Proteins/antagonists & inhibitors , Intracellular Signaling Peptides and Proteins/metabolism , Phosphoproteins/antagonists & inhibitors , Phosphoproteins/metabolism , Phosphorylation/drug effects , Precancerous Conditions/pathology , Protein Biosynthesis/drug effects , Protein Serine-Threonine Kinases/antagonists & inhibitors , Protein Serine-Threonine Kinases/metabolismABSTRACT
The roles of tumor stroma in carcinogenesis are still unclear. This study was aimed at designing an in vitro model for investigating the effects of stromal fibroblasts in the invasive growth of squamous cell carcinoma. Using two cancer cell lines, we performed three-dimensional co-culture with dermal equivalents to evaluate the effects of fibroblasts in cancer invasion. In vitro models for cellular interaction study were designed as follows: a collagen gel-based direct co-culture model (C-Dr) and a collagen gel-based indirect co-culture model (C-In). The invasive growth was found only in the dermal equivalents with fibroblasts. MMP-2 activity could be induced by direct contact between cancer cells and stromal fibroblasts. Cathepsin D was also highly expressed when co-cultured with cancer cells and fibroblasts. The present study demonstrated that the presence of fibroblasts is essential in cancer invasion and that collagen gel-based co-culture models might be useful for invasive study.
Subject(s)
Coculture Techniques/methods , Collagen/pharmacology , Fibroblasts/cytology , Neoplasm Invasiveness/physiopathology , Stromal Cells/cytology , Cathepsin D/biosynthesis , Cell Communication , Cell Line, Tumor , Humans , Matrix Metalloproteinase 2/biosynthesis , Matrix Metalloproteinase 9/biosynthesisABSTRACT
Interferon-alpha (IFN-alpha) has been used to treat hepatitis C Virus (HCV)-induced infection but has been effective in only about half of all patients. It is suggested that the different responses to IFN-alpha treatment in HCV infection may be influenced by HCV genotypes, HCV RNA titer at the beginning of IFN-alpha therapy, and the sequences of the interferon sensitivity determining region (ISDR). However, there have also been reports showing that these have no relation to an IFN-alpha effect. In a previous study, it was found that the nucleotide sequence variation in the hypervariable region (HVR) 1 of the HCV could predict the effect of IFN-alpha. In the present investigation, an attempt was made to determine the predictive factors of IFN-alpha therapy. Twenty-six patients with HCV infection were treated with IFN-alpha. Among these, 13 patients recovered after 3 to 6 months of IFN-alpha treatment, although the other 13 patients showed no response after 6 months of treatment with IFN-alpha. In order to determine the predictive factors of IFN-alpha therapy, the ALT levels, HCV genotypes, HCV serum titer, and the quasispecies of HVR 1 were compared between responders and non-responders. It is suggested that the variation in the HVR 1 and HCV serum titer can be used to predict the effect of IFN-alpha.
