Medulloblastoma is the most common pediatric brain tumor.
However, treatments for children who are diagnosed with so-called medullos have not evolved much over the years and are largely similar to treatments given to adults for other brain tumors.
One frequent event in certain medullos is amplification of two members of the MYC family of oncogenes (see here for background on MYC): MYC itself or MYCN. MYCN can also directly drive medullo formation in a mouse model by Bill Weiss’ lab.
A new, very exciting paper by a team led by one of my favorite scientists, Richard Gilbertson of St. Jude, provide new insights into how medullos likely form and opens new avenues for treatments that might be safer and more effective.
One area of particular interest to me and for my research is the role of epigenetics (see here for background on epigenetics) in medullos and other childhood tumors.
Gilbertson’s team found that genes that encode enzymes that regulate key epigenetic histone marks are frequently mutated in medullos. In particular, two modifications of histone H3 seems important as enzymes that regulate trimethylation of K27 and K4 are often mutated in specific medullo subtypes. Interestingly, these mutations most often did not occur in the same tumors with elevated MYC. One possible interpretation of this observation is that elevated MYC achieves the same end as the mutations in the histone modifying enzymes. Alternatively there may be distinct routes to a common endpoint such as altered chromatin structure with one path involving histone modifying enzymes and another involving MYC, each ultimately leading to the same or similar biological outcomes. Finally it is possible that the combination of increased MYC and mutated histone modifying enzymes may cause apoptosis.
Because histone marks are dynamic, it is possible that a future treatment for medullos could include drugs that target specific histone modifications.
One way you can make a difference in the lives of kids who have the misfortune of having a medullo is through supporting the St. Baldrick’s Foundation (you can learn more about them here in a post I did about them). The Children’s Brain Tumor Foundation (CBTF) is also awesome!