Identification of a panel of mutations and histone methylation patterns in Medulloblastoma of childhood and adolescence

Abstract

Among the malignant solid tumors, tumors of the central nervous system are the major causes of death in patients of childhood and adolescence, and among these, the Medulloblastoma (MB) is the most common tumor, constituting 16-25% of all cases. Currently, despite significant improvements in patient's survival, treatment consists primarily of surgical resection followed by chemotherapy and radiation of marrow and development brain, resulting in serious physical and neurocognitive deficits to patients. Knowledge of the genetic events presents in this tumor has enhanced the individual nature of their classification. Recent evidence suggests that MB contains multiple molecularly distinct entities, whose clinical and genetic differences may require different therapeutic strategies. Previous studies from our group have identified changes in the expression profile of genes known to act in pathways related to development, and change of expression in these genes is related to patient's prognosis and survival. Today we know that the knowledge we have about histopathology of this tumor are not sufficient for an adequate stratification of patients, thus making extremely important the molecular classification. From this, the present study aims to establish a panel to identify mutations in most frequently altered genes in MB, as PTCH1, SUFU, KDM6A, CTNNB1 and DDX3X by SNaPshot sequencing technique, in 30 tumor samples and two cell lines MB; To investigate the role of valproic acid in MB cell lines by cytotoxicity assays, viability, proliferation, invasion and cell migration; investigate KDM6A gene expression and methylation of histones H3K4 and h3k27 through qPCR reactions and Western blotting, respectively; analyze the microRNAs profile in MB by PCR array and relate the molecular findings with clinical features of the MB. Through a better understanding of the molecular and genetic basis of MB, it is expected that in the future, patients will be stratified and treated according to the biology of the disease, and it is expected that might result in significant improvements in patient survival with the reduction of long-term sequelae.