Activation of Crtc1 (also known as Mect1/Torc1) by a t(11;19) chromosomal rearrangement underlies the etiology of malignant salivary gland tumors. As LKB1 is a target for mutational inactivation in lung cancer and was recently shown to regulate hepatic Crtc2/CREB transcriptional activity in mice, we now present evidence suggesting disruption of an LKB1/Crtc pathway in cancer. Although Crtc1 is preferentially expressed in adult brain tissues, we observed elevated levels of steadystate Crtc1 in thoracic tumors. In addition, we show that somatic loss of LKB1 is associated with underphosphorylation of endogenous Crtc1, enhanced Crtc1 nuclear localization and enhanced expression of the Crtc prototypic target gene, NR4A2/Nurr1. Inhibition of NR4A2 was associated with growth suppression of LKB1 null tumors, but showed little effect on LKB1-wildtype cells. These data strengthen the role of dysregulated Crtc as a bona fide cancer gene, present a new element to the complex LKB1 tumorigenic axis, and suggest that Crtc genes may be aberrantly activated in a wider range of common adult malignancies.

Glioma accounts for 80% of all malignant brain tumors and is the most common adult primary brain tumor. Age is an important factor affecting the development of cancer as somatic mutations accumulate with age. In this study, we aimed to analyze the significance of age-related non-silent somatic mutations in glioma prognosis. Histological tumor grade depends on age at diagnosis in patients with IDH1, TP53, ATRX, and EGFR mutations. The hierarchical clustering of patients was dominantly separated by IDH1 and EGFR mutations. Furthermore, patients with IDH1 mutation were dominantly separated by TP53 and ATRX double mutation and its double wildtype counterpart. Patients with the double mutation showed poorer prognosis than those with the double wild type genotype. In conclusion, among the many somatic mutations, those in IDH1, TP53, ATRX, and EGFR are important for glioma classification based on histological grade. Patients with EGFR mutation had the poorest prognosis, whereas those with only IDH1 mutation showed the best prognosis.