Human prostate epithelial cells and prostate-derived stem cells malignantly transformed in vitro with sodium arsenite show impaired Toll like receptor -3 (TLR3)-associated anti-tumor pathway.

A therapeutic strategy for prostate cancer (PCa) involves the use of 9-cis-retinoic acid (9cRA) to induce cancer stem cells (CSCs) differentiation and apoptosis. Polyinosinic:polycytidylic acid (PIC) is a Toll-like receptor 3 (TLR3) agonist that induces tumor cells apoptosis after activation. PIC+9cRA combination activates retinoic acid receptor ß (RARß) re-expression, leading to CSC differentiation and growth arrest. Since inorganic arsenic (iAs) targets prostatic stem cells (SCs), we hypothesized that arsenic-transformed SCs (As-CSCs) show an impaired TLR3-associated anti-tumor pathway and, therefore, are unresponsive to PIC activation. We evaluated TLR3-mediated activation of anti-tumor pathway based in RARß expression, on As-CSC and iAs-transformed epithelial cells (CAsE-PE). As-CSCs and CAsE-PE showed lower TLR3 and RARß basal expression compared to their respective isogenic controls WPE-Stem and RWPE-1. Also, iAs transformants showed reduced expression of mediators in TLR3 pathway. Importantly, As-CSCs were irresponsive to PIC+9cRA in terms of increased RARß and decreased SC-markers expression, while CAsE-PE, a heterogeneous cell line having a small SC population, were partially responsive. These observations indicate that iAs can impair TLR3 expression and anti-tumor pathway activated by PIC+9cRA in SCs and prostatic epithelial cells. These findings suggest that TLR3-activation based therapy may be an ineffective therapeutic alternative for iAs-associated PCa.

Methyl gallate attenuates inflammation induced by Toll-like receptor ligands by inhibiting MAPK and NF-Κb signaling pathways.

OBJECTIVE AND DESIGN: Methyl gallate (MG) is a prevalent polyphenol in the plant kingdom, which may be related to the effects of several medicinal plants. Although it is widely reported that polyphenols have therapeutic effects, there are few studies demonstrating that MG has anti-inflammatory action. This study aimed to investigate the molecular mechanism behind the anti-inflammatory activity of MG and its effect on hyperalgesia. METHODS: Swiss mice were pretreated orally with different doses of MG and subjected to i.pl. injection of zymosan to induce paw edema. RAW264.7 macrophages and BMDMs stimulated with different TLR agonists such as zymosan, LPS, or Pam3CSK4 were used to investigate the molecular mechanisms of MG RESULTS: MG inhibits zymosan-induced paw edema and hyperalgesia and modulates molecular pathways crucial for inflammation development. Pretreatment with MG inhibited cytokines production and NF-κB activity by RAW 264.7 cells stimulated with zymosan, Pam3CSK4 or LPS, but not with PMA. Moreover, pretreatment with MG decreased IκB degradation, nuclear translocation of NF-κBp65, c-jun and c-fos and ERK1/2, p38 and JNK phosphorylation. CONCLUSION: Thus, the results of this study demonstrate that MG has a promising anti-inflammatory effect and suggests an explanation of its mechanism of action through the inhibition of NF-κB signaling and the MAPK pathway.

The Role of Toll Like Receptors (TLRs) in Oral Carcinogenesis.

Oral cancer accounts for 10% of head and neck tumors. Despite the recent advancements in surgical techniques, as well as in chemo- and radiotherapy therapeutic protocols, survival rates for oral cancer patients have not improved significantly in the last decades. Recently, toll like receptors (TLRs) have been described as promoters of cell proliferation, invasiveness, and angiogenesis in a variety of cancers. The aim of this review is to identify how TLRs participate in oral carcinogenesis in order to evaluate their biological relevance. Data revealed that some TLRs participate in oral carcinogenesis since TLR5 and TLR9 promote tumor growh, whereas TLR3 is closely involved to anti-cancer properties. They represent a promising alternative for oral cancer therapy. However, TLR2, TLR4 and TLR7 need further investigation, since current data are not sufficient to conclude about their role. Certainly, such data will contribute to new scientific knowledge, which will be incorporated to the preventive actions and therapeutic protocols for oral cancer patients suffering from this devasting disease.