Abstract: Medulloblastoma (MB) is the most common malignant brain tumor of children. To identify the genetic alterations in this tumor type, we searched for copy number alterations using high density microarrays and sequenced all known protein-coding genes and miRNA genes using Sanger sequencing. We found that, on average, each tumor had 11 gene alterations, markedly fewer than in common adult cancers. In addition to alterations in the Hedgehog and Wnt pathways, our analysis led to the discovery of genes not previously known to be altered in MBs. Most notably, inactivating mutations of the histone H3K4 trimethylase genes MLL2 or MLL3 were identified in 16% of MB patients. These results demonstrate key differences between the genetic landscapes of adult and childhood cancers, highlight dysregulation of developmental pathways as an important mechanism underlying MBs, and identify a role for a specific type of histone methylation in human tumorigenesis.

Abstract: Given the important role of protein kinases in pathways affecting cellular growth and invasion, we have analyzed 340 serine/threonine kinases for genetic mutations in colorectal cancers. Mutations in eight genes were identified, including three members of the phosphatidylinositol-3-kinase (PI3K) pathway; the alterations in the latter genes each occurred in different tumors and did not overlap with mutations in PIK3CA or other non-serine-threonine kinase (STK) members of the PI3K pathway, suggesting that mutations in any of these genes had equivalent tumorigenic effects. These data demonstrate that the PI3K pathway is a major target for mutational activation in colorectal cancers and provide new opportunities for therapeutic intervention.

Abstract: Medulloblastoma (MB) is the most common malignant brain tumor of children. To identify the genetic alterations in this tumor type, we searched for copy number alterations using high density microarrays and sequenced all known protein-coding genes and miRNA genes using Sanger sequencing. We found that, on average, each tumor had 11 gene alterations, markedly fewer than in common adult cancers. In addition to alterations in the Hedgehog and Wnt pathways, our analysis led to the discovery of genes not previously known to be altered in MBs. Most notably, inactivating mutations of the histone H3K4 trimethylase genes MLL2 or MLL3 were identified in 16% of MB patients. These results demonstrate key differences between the genetic landscapes of adult and childhood cancers, highlight dysregulation of developmental pathways as an important mechanism underlying MBs, and identify a role for a specific type of histone methylation in human tumorigenesis.

Abstract: Given the important role of protein kinases in pathways affecting cellular growth and invasion, we have analyzed 340 serine/threonine kinases for genetic mutations in colorectal cancers. Mutations in eight genes were identified, including three members of the phosphatidylinositol-3-kinase (PI3K) pathway; the alterations in the latter genes each occurred in different tumors and did not overlap with mutations in PIK3CA or other non-serine-threonine kinase (STK) members of the PI3K pathway, suggesting that mutations in any of these genes had equivalent tumorigenic effects. These data demonstrate that the PI3K pathway is a major target for mutational activation in colorectal cancers and provide new opportunities for therapeutic intervention.