DNA Methylation and gene expression variations influence pituitary adenoma hormonal function and invasive growth Pituitary Adenomas (PAs) are among the most common intracranial tumors, and may cause hypopituitarism, neurological deficits, and lethal hormonal oversecretion disorders such as Cushing's disease and acromegaly. Although typically benign, PA invasion into surrounding dura, bone, and brain is evident in nearly half of symptomatic patients and is the major barrier to achieving long-term tumor control, hormonal remission, and normalized patient survival. Genetic mutations do not play a major role in the development or behavior of non-familial PAs, and a major knowledge gap exists in understanding the molecular underpinnings of PA hormonal function and invasive growth. Alternatively, epigenetic (e.g., DNA methylation) and gene expression alterations are known to influence PA phenotype, but these effects vary with gene location and context. Our team performed the first epigenome-wide pilot study to explore the association of DNA methylation and gene expression with PA behavior, and validated several genes implicated in PA hormonal function and invasion. Using a similar workflow, our overall goal is to define the role that DNA methylation and gene expression play in PA hormonal secretion and invasion in a larger study stratified according to PA hormonal subtype and invasion status. We hypothesize that: 1) variation in DNA methylation and expression is associated with subtype-specific PA hormonal function and invasion; 2) DNA methylation and expression data can be used to identify novel molecularly-defined PA classes and complement current PA diagnostic schemes; and 3) modulated expression of prioritized genes of interest will affect PA hormonal secretion and invasion in vitro. To test these hypotheses, we aim to: 1) use integrative epigenomic profiling and RNA sequencing approaches to analyze surgically-resected invasive and noninvasive PAs derived from a multi-institutional consortium, 2) discover novel molecularly-defined PA subtypes using DNA methylation and gene expression analysis, followed by development of a molecularly-based classification and unified diagnostic scheme, 3) identify candidate DNA methylation and gene expression markers associated with PA hormonal secretion and invasion, 4) use established rat and surgically-resected human PA primary cell lines to test hormonal secretion and invasion phenotypes following modulation of expression of prioritized genes. Understanding the molecular pathways associated with PA hormonal secretion and invasion will provide practitioners with more precise diagnostic information and help to develop targeted drug therapies to curb or reverse PA hormonal oversecretion and invasion, thereby improving patient quality of life and survival. Knowledge derived from this study could help refractory PA patients by helping to mitigate lifelong risks associated with chronic hormone oversecretion, medications, radiation treatment, and repeat surgery.
Pituitary adenomas (PAs) may cause significant disability or death due to hormonal oversecretion and neurological deterioration caused by invasive tumor growth. PA hormonal secretion and invasive growth are explained in part by epigenetic mechanisms (e.g., DNA methylation) affecting gene expression, rather than gene mutations. Our study will compare epigenetic and gene expression signatures in invasive versus noninvasive PAs of various hormonal subtypes, thereby providing key insights into gene pathways and mechanisms associated with PA behavior, aiding in the diagnosis and molecular classification of PAs, and helping to guide development of precision drugs to curb or arrest hormonal secretion and invasive growth in patients with refractory PA disease.
