M2-polarized tumor-associated macrophages (TAMs) are key regulators of the link between inflammation and cancer. A negative correlation between infiltration intensity of M2-polarized TAMs and prognosis of pancreatic cancer has been reported. Epithelial-mesenchymal transition (EMT) is an important biological process in the progression of primary tumors toward metastasis. Inflammation-induced EMT has been previously shown, therefore, we hypothesized M2-polarized TAMs could induce EMT in pancreatic cancer. Toll-like receptor 4 (TLR4) signaling has an active role in tumor progression during chronic inflammation and the receptor is primarily expressed on macrophages. Activation of TLR4 on M2-polarized TAMs stimulates an increase in the cytokine interleukin-10 (IL-10); consequently, another aim was to investigate the potential role of TLR4/IL-10 signaling in the EMT of pancreatic cancer. Treatment with IL-4 (20 ng/ml) for 24 h successfully induced the polarization of macrophage cell line RAW 264.7 to M2 phenotype, IL-10 high , IL-12 low , and IL-23 low , and high expression of CD204 and CD206. A coculture system allowed investigation of the roles of M2-polarized TAMs and TLR4/IL-10 signaling in the EMT of Panc-1 and BxPC-3 pancreatic cancer cell lines. Our results showed that coculture with M2-polarized TAMs increased fibroblastic morphology, upregulated mesenchymal markers vimentin and snail at the mRNA and protein levels, and increased proliferation, migration, and metalloproteinase (MMP)2 and MMP9 proteolytic activity in pancreatic cancer cells. Simultaneously, coculture with M2-polarized TAMs decreased the expression of the epithelial marker E-cadherin. Coculture with pancreatic cancer cells increased TLR4 mRNA and protein expression in M2-polarized TAMs. Application of TLR4 siRNA and neutralizing antibodies against TLR4 and IL-10 markedly inhibited E-cadherin reduction and the upregulation of snail and vimentin. Furthermore, activation of TLR4 signaling by lipopolysaccharide profoundly increased the EMT of pancreatic cancer cells. In conclusion, M2-polarized TAMs promoted EMT in pancreatic cancer cells partially through TLR4/IL-10 signaling, suggesting novel therapeutic strategies and enhancing our understanding of M2-polarized TAMs. Pancreatic ductal adenocarcinoma is highly malignant and is resistant to chemo-and radiotherapeutics. 1 Recent evidence suggests the inflammatory environment of the tumor is critical for its progression. 2 Tumor-associated macrophages (TAMs) are derived from circulating monocytes, which are highly abundant within the tumor and provide a key link between inflammation and cancer. 3 TAMs develop a phenotype similar to M2-polarized macrophages and respond to recruitment to the tumor microenvironment. 4 Previous studies have commonly associated elevated numbers of TAMs with tumor progression and poor patient outcome. 5 This association is likely linked to the typical presence of M2-polarized TAMs during cancer invasion, 6 however, the exact mechanisms by which these cells influence the pr...

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Lung carcinoma is the most common human cancer with poor prognosis and has an increasing incidence in recent years. However, the related mechanism of lung cancer onset has not been completely explored. Piwi-interacting RNA (piRNA) is a type of noncoding small RNA with established function in germ cells, and interestingly, piRNA has also been shown to be implicated in cancer biology. In this study, piR-55490 was found to be silenced in lung carcinoma specimens and cell lines, compared with normal lung tissues and cells. Intriguingly, the expression level of piR-55490 is negatively associated with patients' survival. Restoration of piR-55490 can reduce the proliferation rates of lung cancer cells, while piR-55490 suppression led to the gain in the proliferation rates. Animal model study showed that piR-55490 can suppress the growth of lung carcinoma xenograft. Further study revealed that piR-55490 suppressed the activation of Akt/mTOR pathway in lung cancer cells. Surprisingly, piR-55490 was found to bind 3'UTR of mTOR messenger RNA (mRNA) and induce its degradation in a mechanism similar to microRNA (miRNA). The introduction of an mTOR construct resistant to action of piR-55490 was able to abolish the effect of piR-55490 on lung cancer cells. In conclusions, we found that piRNA can contribute to the suppression of cancer cell phenotypes by directly targeting a oncogene mRNA. This finding facilitates our understanding of piRNA's function and its association with human cancer.

Over-expression of TROP2 (the trophoblast cell surface antigen 2) was reported to predict poor prognosis in various solid tumors in number of studies. However, the results remained not comprehensive. Therefore, we here carried out this meta-analysis of relevant studies published on this topic to quantitatively evaluate the clinicopathological significance of TROP2 in solid tumors. Relevant articles were identified through searching the PubMed, Web of Science and Embase database. The primary outcomes were overall survival (OS) and disease-free survival (DFS). In this meta-analysis, 16 studies involving 2,569 participants were included, and we drew the conclusion that TROP2 overexpression was significantly associated with poor OS (pooled HR = 1.896, 95% CI = 1.599–2.247, P < 0.001) and short DFS (pooled HR = 2.336, 95% CI = 1.596–3.419, P < 0.001). Furthermore, the subgroup analysis revealed that the associations between TROP2 overexpression and the outcome endpoints (OS or DFS) were significant in in patients with female genital system neoplasms, as well in gastrointestine neoplasms. In addition, subgroup analysis found no difference HR across populations of different descent.Taken together, TROP2 overexpression was associated with poor survival in human solid tumors. TROP2 may be a valuable prognosis predictive biomarker and a potential therapeutic target in human solid tumors.