Our next speaker is Douglas Tucker, and he'll be speaking about Integrative Analysis Implicates MYC and MAX in Functional Pituitary Adenomas. Good afternoon. My name is Douglas Tucker. I'm a second-year medical student at USC, and I'm going to be discussing an integrative analysis implicating MYC and MAX in functional pituitary adenomas. I have no disclosures. Pituitary adenomas are monoclonal tumors that arise in the anterior pituitary gland, and the two most commonly surgically resected pituitary adenomas are nonfunctional and growth hormone secreting. These growth hormone secreting tumors cause gigantism and acromegaly in patients. Acromegaly is a neuroendocrinopathy that significantly reduces overall survival and quality of life if it isn't controlled. We undergo a multimodality treatment method using surgical resection, which is the primary way we treat, along with medical therapy, radiosurgery. And refractory disease is often due to invasion of these tumors. Now growth hormone secreting tumors have a propensity to invade the infracellar, whereas nonfunctional tumors, they tend to grow up and have supercellar extension. From our own cohort of 544 patients, growth hormone secreting tumors have about a three times greater rate of recurrence versus nonfunctional adenomas, 21% versus about 7%. In addition, when these tumors do recur in growth hormone secreting tumors, it occurs in about five years versus greater than 15 with the nonfunctional adenomas. These are two very different tumors, and they need to be treated as such. Additionally, pre-op IGF-1, which correlates to growth hormone secretion, the higher it is, it's a poor prognostic marker. So growth hormone secretion is also important with these patients. So we wanted to look at methylation because primary mutations are uncommon in non-familiar PAs. So we looked at DNA methylation. We did a genome-wide methylation analysis of nonfunctional and growth hormone pituitary adenomas. This is an IRB-approved study with 58 surgically resected PAs, 40 of which were nonfunctional and 18 of which were functional, and 17 of these 18 were growth hormone secreting. We then did a full DNA methylation analysis using Illumina EPIC technology, which looks at over 850,000 different loci for methylation status. So to begin, on the left-hand side, we can see all of our functional tumors. And generally speaking, these functional tumors are hypomethylated compared to the nonfunctional tumors. So there's an increased ability for transcription and other transcription factors to bind. And there were nine loci of interest of us in particular because these have transcription factor binding sites for MYC and MAX, which are oncogenes, which are their transcription factors, which have been implicated in a number of different malignancies, including small cell lung cancer, pheochromocytomas, and neuroendocrine tumors. So we then did a motif analysis to look at the specific sequences and if there were changes in the specific sequences that transcription factors bind to. So what this allowed us to do is see changes in the actual sequence. And there were two main pathways that popped out for us, and that's the MAX pathway and the FLY-ERG pathway. The FLY-ERG pathway has been seen in mesenchymal tumors, but we really wanted to focus on the MYC and MAX. So the specific sequence that these transcription factors bind to is hypomethylated in these growth hormone-secreting tumors. We then analyzed changes in copy number, and copy number should correlate to increased expression. And we saw a statistical significance in there's an increased copy number of MAX within these growth hormone-secreting tumors. So that, in theory, should lead to increased expression. That's the next thing we did, immunohistochemistry on nonfunctional and growth hormone-secreting adenomas, and we did this for MYC, and we saw increased protein expression, and we saw the same thing for MAX. So there's co-overexpression of both MYC and MAX in growth hormone-secreting adenomas compared to nonfunctional adenomas. So in conclusion, MYC and MAX binding sites are hypomethylated, so there's an increased ability for transcription factors to bind. In addition, these key transcription factors have increased copy number and increased protein expression. And these changes may be involved in tumorigenesis and growth hormone over-secretion, and this may be a targetable pathway in the future for control of these patients with acromegaly. So in the future, we'd like to do more immunohistochemistry on more patients. We have about 15 to 20 patients. We'd like to expand that. We're creating a tissue microarray to do so. We'd also like to investigate the fly-ERG pathway a little bit deeper. We'd also, as these are transcription factors, there are often many downstream effects. So we'd like to do transcriptome sequencing and targeted PCR to see what these increased transcription factors do. And we'd like to inhibit both MYC and MAX using in vitro and in vivo, and see if we can alter levels of growth hormone secretion as well as changes in invasion, as invasion is part of the reason for refractory disease. So I'd like to thank Dr. Zada, Dr. Ghebrezadeh, Dr. John Carmichael, and Dr. Hurth, who helped me with this project, as well as ANS and USC.

functional pituitary adenomas

growth hormone-secreting tumors

DNA methylation

transcription factor binding sites

MAX pathway