A possible link between chronic inflammation, TLR expression and oncogenesis A-769662 cost also can be found in colorectal cancer. Nine TLRs (TLR1-9) are expressed in normal epithelial cells of the colon; three of these TLRs (TLR2-4) are elevated in most colorectal cancer cell lines. Elevated expression

seems to be regulated by commensal bacteria in the intestinal lumen [26]. TLR4 reportedly is overexpressed in colorectal cancer cells from patients with colitis and in colorectal cancer cells from a murine model of colitis; interestingly, colorectal neoplasia is reduced in TLR4-deficient mice [4]. In the same study, activation of TLR4 by LPS led to neoplastic transformation via enhanced COX-2 expression and increased epidermal growth factor receptor (EGFR) signaling. This suggests that chronic inflammation caused by commensal bacteria in the microenvironment may be responsible for carcinogenesis SAHA HDAC in vitro through TLR signaling. Epithelial cells of the female reproductive tract may acquire carcinogenic changes through continuous TLR stimulation by PAMPs. Four TLRs (TLR2-5) are expressed by ovarian cancer cell lines [12]. TLR4 activation by LPS promotes survival of ovarian cancer cells by inducing the expression of antiapoptotic proteins,

including X-linked inhibitor of apoptosis (XIAP) and phosphorylated Akt [27]. Two TLRs (TLR5 and TLR9) might contribute to cervical carcinogenesis [8, 28]. The expression of TLR5 Olopatadine and TLR9 is absent or weak in normal cervical squamous epithelial cells but gradually increases during progression of low-grade cervical intraepithelial neoplasia (CIN) to high-grade CIN and then to invasive cervical squamous cell carcinoma. Four TLRs (TLR2-4 and 9) are expressed in lung cancer cell lines. Activation of TLR4 by LPS induces resistance of lung cancer cells to TNFα or TRAIL-induced apoptosis through NF-κB upregulation [6]. Various levels of TLR9 expression

are observed in tumor specimens from patients with prostate cancer [7, 29], breast cancer, astrocytoma and glioblastoma [30]. Activation of TLR9 by CpG-ODN or bacterial DNA increases cancer cell invasion. We recently reported high expression of three TLRs (TLR2-4) in human cutaneous melanoma. Our in vivo and in vitro studies showed that other TLRs were expressed less frequently or at lower levels. All three TLRs were functionally active. Stimulation with ligands specific for each TLR (zymosan for TLR2, polyIMP/buy PS-341 polyCMP [PIC] for TLR3, and LPS for TLR4), upregulated TLR expression and activated the adaptor protein MyD88 and NF-κB. After stimulation, TLRs induced several inflammatory cytokines and chemokines, as discussed in the next section, and melanoma cell migration increased [5].