The cells were cultured under feeder-free culture conditions

il based chemotherapy, but not significantly. It revealed that the role of RRM1 in drug resistance of GC needs to be further explored. Due to these potential confounding factors, TNM stage, tumor location, tumor grade, tumor size, Ki67 level and Celgosivir cost chemotherapy were taken into consideration in the stratification analysis. Some variances were observed in the different subgroups, but overall, the data indicate that RRM1 predicts poor prognosis in GC. Different antibodies used for detecting RRM1 protein expression and localization also could potentially lead to different RRM1 Predicts Poor Survival of Gastric Cancer conclusions. Certain antibodies, such as R1AS6, recognize mainly nuclear RRM1, but others visualize the cytoplasmdominant IHC pattern, such as the RRM1 polyclonal antibody from the Protein Tech group and Accurate Chemicals AD203. To avoid this type of bias, we developed our own monoclonal antibodies. The sensitivity of the antibodies for IHC was optimized, and the specificity was verified by a peptide blocking test. Therefore, we believe the RRM1 antibodies used in this study were reliable. We observed that RRM1 was dominantly located in the cytoplasm during serum starvation and translocated to the nucleus under serum re-supplementation. In human GC tissue 10646850 samples, RRM1 was seen heterogeneously in the cytoplasm and nucleus by IHC staining. The clinical relevance of cytoplasmic and nuclear RRM1 was evaluated independently. Consistent results were obtained from cytoplasmic and nuclear RRM1 scoring. These RRM1 Predicts Poor Survival of Gastric Cancer results suggest that both cytoplasmic and nuclear RRM1 are significantly associated with advanced TNM stage and lead to poor outcomes in GC patients. The mammalian RNR subunits R1 and R2 play opposing roles in malignancy suppression/progression through the Ras/Raf/ MAPK signaling pathway in Ras-transformed 3T3 cells. And there are also some studies explain why RRM1 and RRM2 play opposite roles in cancer outcomes. Here, the relationship between RRM1 and the malignancy of GCs was further examined in cultured cells and tissue samples. In human subjects, we detected a positive association between RRM1 and pERK in GC samples. The in vitro data reveal that high RRM1 expression significantly increased p-ERK and cell proliferation. 14557281 To further explore the role of RRM1, we downregulated RRM1 using siRNA in AGS and NCI-N87 GC cells. With RRM1 knocked-down, Ras/Raf activation was suppressed, and p-MEK and p-ERK also decreased significantly. The reduction of the dNTP pool and growth retardation could be seen in AGS and NCI-N87 cells after RRM1 siRNA treatment, which is consistent with the fact that the Ras/Raf/MAPK signaling pathway is related to cancer cell growth and metastasis. The gelatin zymography assay demonstrated that MMP activity decreased upon down-regulation of RRM1. Inhibiting RRM1 expression also decreased the invasion ability of GC cells. Obviously, this result is not consistent with previous findings using NIH 3T3 cells. The conflicting results might be caused by using different cell types and species. Regardless, this result was compatible with our findings in human subjects. There were some limitations to the current study. First, certain biases, such as selection bias, observer bias, measurement bias and confounders could not be completely avoided in this retrospective study. Nevertheless, these limitations have been taken into consideration. To make our conclusion more reliable, w