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Background Arginase-1 (ARG1), a urea cycle-related enzyme, catalyzes the hydrolysis of arginine to urea and ornithine, which regulates the proliferation, differentiation, and function of various cells. However, it is unclear whether ARG1 controls the progression and malignant alterations of colon cancer. Methods We established metastatic colonization mouse model and ARG1 overexpressing murine colon cancer CT26 cells to investigate whether activation of ARG1 was related to malignancy of colon cancer cells in vivo. Living cell numbers and migration ability of CT26 cells were evaluated in the presence of ARG inhibitor in vitro. Results Inhibition of arginase activity significantly suppressed the proliferation and migration ability of CT26 murine colon cancer cells in vitro. Overexpression of ARG1 in CT26 cells reduced intracellular l-arginine levels, enhanced cell migration, and promoted epithelial-mesenchymal transition. Metastatic colonization of CT26 cells in lung and liver tissues was significantly augmented by ARG1 overexpression in vivo. ARG1 gene expression was higher in the tumor tissues of liver metastasis than those of primary tumor, and arginase inhibition suppressed the migration ability of HCT116 human colon cancer cells. Conclusion Activation of ARG1 is related to the migration ability and metastatic colonization of colon cancer cells, and blockade of this process may be a novel strategy for controlling cancer malignancy.

Background The purpose of this study was to evaluate the survival outcome for middle ear cancer and to construct prognostic models to provide patients and clinicians with more accurate estimates of individual survival probability. Methods Patients diagnosed with middle ear cancer between 1983 and 2011 were selected for the study from the Surveillance Epidemiology and End Results Program. We used the Kaplan-Meier product limit method to describe overall survival and cause-specific survival. Cox proportional hazards models were fitted to model the relationships between patient characteristics and prognosis. Nomograms for predicting overall survival and cause-specific survival were built using the Cox models established. Results The entire cohort comprised 247 patients with malignant middle ear cancer. Median duration of follow-up until censoring or death was 25 months (range, 1–319 months). Five-year overall survival and cause-specific survival were 47.4% (95% Confidence Interval (CI), 41.2% to 54.6%) and 58.0% (95% CI, 51.6% to 65.3%), respectively. In multivariable analysis, age, histological subtype, stage, surgery and radiotherapy were predictive of survival. The bootstrap corrected c-index for model predicting overall and cause-specific survival was 0.73 and 0.74, respectively. Calibration plots showed that the predicted survival reasonably approximated observed outcomes. Conclusion The models represent an objective analysis of all currently available data. The resulting models demonstrated good accuracy in predicting overall survival and cause-specific survival. Nomograms should thus be considered as a useful tool for predicting clinical prognosis.