Medical records show that certain types of brain tumors are more frequent among males than females. Records also show that brain tumors tend to be more malignant among men. Medulloblastomas (during childhood) and glioblastomas—two types of malignant tumors—are roughly twice as common in males than in females. And while meningiomas are more frequent in women, these tumors are more malignant among men. Overall, men face significantly worse prognoses once diagnosed with a brain tumor. Why is that? Groundbreaking research at Washington University in St-Louis has uncovered the reason behind this gender disparity in malignant brain tumor risk.
Knowing that the gender disparity in brain tumor risk cannot be explained by sex hormones, scientists at the Washington University School of Medicine decided to direct their attention at the cells and three genes known to be implicated in the growth of tumors in the human body - Tp53, RB and NB1. Working with cell models of glioblastomas in male and female brain cells, scientists were able to uncover why malignant brain tumors are more frequent in males. The culprit was found to be the retinoblastoma protein, which is encoded by the RB gene. The retinoblastoma protein is instrumental in the prevention cancerous cell growth because it regulates cell-division cycles. It's a tumor suppressor protein. It was observed that this protein is less active in male brain cells, thus, resulting in a higher incidence of malignant tumors.
Researchers proceeded to inactivate retinoblastoma protein in female brain cells, which, as a result, became equally prone to tumor growth. Professor Joshua Robin at Washington University is the senior author of the study. He highlighted that this was the first study ever to demonstrate cellular differences between the sexes that explained the disparities in brain tumor incidence.
The study was published in The Journal of Clinical Investigation back in 2014. Professor Joshua Robin stated that, at the time of the study, new drugs targeting retinoblastoma protein were already undergoing clinical trials.
Glioblastoma multiforme is the most common and aggressive malignant brain tumor. Symptoms vary depending on the specific brain regions involved, but the most common ones are progressive shifts in neurological, personality and memory capabilities. The condition may also develop asymptomatically. Relapse is common and, as of 2014, the five-year survival rate was lower than 5% (one of the deadliest of all cancers). Currently, there is no cure or way to prevent it. A new class of drugs targeting the retinoblastoma protein could offer better treatment solutions not only for brain cancer among males but also other types of cancer given that some degree of retinoblastoma protein mutation is typically involved in cancerous cell proliferation.
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