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Item Does miRNA-155 Promote Cyclooxygenase-2 Expression in Cancer?(Wiley, 2015-11) Comer, Brian S.; Department of Cellular and Integrative Physiology, IU School of MedicineMicroRNA (miR)-155 and cyclooxygenase (COX)-2 are both elevated in numerous cancers including colorectal cancer. MiR-155 enhances COX-2 expression and is an established regulator of epithelial-mesenchymal transition and inflammation. Inhibition of miR-155 or COX-2 exhibit similar negative effects on tumorigenicity. Thus, it is hypothesized that miR-155 may be a promising target for antagonizing COX-2 expression in colorectal and other cancers.Item Sparse Estimation of Cox Proportional Hazards Models via Approximated Information Criteria(Wiley, 2016-09) Su, Xiaogang; Wijayasinghe, Chalani S.; Fan, Juanjuan; Zhang, Ying; Department of Biostatistics, Richard M. Fairbanks School of Public HealthWe propose a new sparse estimation method for Cox (1972) proportional hazards models by optimizing an approximated information criterion. The main idea involves approximation of the inline image norm with a continuous or smooth unit dent function. The proposed method bridges the best subset selection and regularization by borrowing strength from both. It mimics the best subset selection using a penalized likelihood approach yet with no need of a tuning parameter. We further reformulate the problem with a reparameterization step so that it reduces to one unconstrained nonconvex yet smooth programming problem, which can be solved efficiently as in computing the maximum partial likelihood estimator (MPLE). Furthermore, the reparameterization tactic yields an additional advantage in terms of circumventing postselection inference. The oracle property of the proposed method is established. Both simulated experiments and empirical examples are provided for assessment and illustration.