Yuta Horita

ABSTRACTAdrenocortical cancer poses a significant clinical challenge due to its aggressiveness and limited treatment options. Herein, we investigated the role of NR2F1, as a potential dormancy factor, and its relationship with glutamine-dependency of adrenocortical cancer cells. Materials and Methods: NR2F1 expression was evaluated in adrenocortical cancer, in publicly available databases. H295R adrenocortical cancer cells and HAdCC normal adrenocortical cells transfected to overexpress NR2F1, were analyzed for cell viability, lysosome function, and protein expression of cell-cycle regulators, as well as for cell-cycle distribution. Kaplan-Meier analyses of publicly available databases showed a marginal positive association of NR2F1 expression with OS in adrenocortical cancer. Transient overexpression of NR2F1 in H295R cells resulted in suppressed proliferation and increased lysosome function. In normal human AdCC adrenocortical cells, lysosome activity was increased in glucose- and glutamine- deprived state, only when the cells were confluent. On the contrary, in H295R cells, lysosome activity was reduced in glucose- and glutamine- deprived states, only when the cells were confluent. Western blot analyses showed that the expression of NR2F1 was induced by confluency. Confluency also induced a marked increase in CDK1 and CDKN1A expression, which was significantly reduced by glutamine deprivation in H295R cells. Our findings provide new insights into the molecular mechanisms underlying the role of NR2F1 in cellular dormancy, as well as the expression patterns of CDK1 and CDKN1A in response to confluency and glutamine dependency, suggesting an interdependence of these pathways as potential therapeutic targets in adrenocortical cancer. Keywords: Adrenocortical cancer, NR2F1, dormancy, glutamine deprivation.

ABSTRACTMetformin ameliorates insulin resistance and reported to have prophylactic potential in breast cancer. The estrogen receptor-alpha gene is known to be alternatively spliced to the ER?46 isoform with decreased expression in tamoxifen-resistant breast cancer cells. We show here that metformin had a differential effect on its alternative splicing in MCF-7 and its tamoxifen-resistant derivative, TAMR1 cells. Metformin altered the tamoxifen-induced expression of ER?46 and treatment of cell-transplanted nude mice showed decreased tumor weight only in TAMR1 cell tumors. This is the first report to show metformin specifically involved in alternative splicing of genes in breast cancer cells. Keywords: Estrogen receptor-alpha (ER?), estrogen, tamoxifen, metformin