The adaptive immune response to sporadic cancer

Most of the current experimental cancer models do not reflect the pathophysiology of real-life cancer. Cancer usually occurs sporadically and is clonal in origin. Between tumor initiation and progression, clinically unapparent pre-malignant cells may persist for years or decades in humans. Recently, mouse models of sporadic cancer have been developed. The mouse germ-line can be engineered with high precision so that defined genes can be switched on and off in the adult organism in a targeted manner. Analysis of the immune response against sporadic tumors requires the knowledge of a tumor antigen. Ideally, a silent oncogene, for which the mice are not tolerant, is stochastically activated in individual cells. This approach offers the opportunity to analyze the adaptive immune response throughout the long process of malignant transformation and most closely resembles cancer in humans. In such a model with the highly immunogenic SV40 large T antigen as a dormant oncogene, we discovered that sporadic cancer is recognized by the adaptive immune system at the pre-malignant stage, concomitant with the induction of tumor antigen-specific tolerance. These results demonstrated that even highly immunogenic sporadic tumors are unable to induce functional cytotoxic T lymphocytes. Based on this model, we conclude that immunosurveillance plays little or no role against sporadic cancer and that tumors must not escape immune recognition or destruction

How important are student-selected versus instructor-selected literature resources for students’ learning and motivation in problem-based learning?

In problem-based learning (PBL) students are responsible for their own learning process, which becomes evident in, for example, selecting literature resources for individual study. Debate exists about whether it is best to have students select their own literature resources or to present them with a list of mandatory instructor-selected literature resources. The current study investigated the effect of studying instructorselected literature resources versus student-selected literature resources (N = 60) from a predetermined set of literature on several study outcome variables. The results demonstrated that students in the student-selected literature condition scored higher on autonomous motivation, perceived competence, and lower on perceptions of mental effort during studying. The instructor-selected condition led to better test performance on factual test items whereas no difference was found for the conceptual questions. Overall, the results indicate that letting students select their own literature resources can be beneficial in terms of autonomous motivation, perceived competence, and perceptions of mental effort during learning and does not affect conceptual knowledge