Mitogen-Activated Protein Kinase Pathway: Genetic Analysis of 95 Adrenocortical Tumors

Hereditary Endocrine Tumor Registries

Context

Endocrine neoplasia syndromes are phenotypically complex, and there is a misconception that they are universally rare. Genetic alterations are increasingly recognized; however, true prevalence is unknown. The purpose of a clinical registry is to monitor the quality of health care delivered to a specified group of patients through the collection, analysis, and reporting of relevant health-related information. This leads to improved clinical practice, decision-making, patient satisfaction, and outcome.

Objective

This review aims to identify, compare, and contrast active registries worldwide that capture data relevant to hereditary endocrine tumors (HETs).

Methods

Clinical registries were identified using a systematic approach from publications (Ovid MEDLINE, EMBASE) peer consultation, clinical trials, and web searches. Inclusion criteria were hereditary endocrine tumors, clinical registries, and English language. Exclusion criteria were institutional audits, absence of clinical data, or inactivity. Details surrounding general characteristics, funding, data fields, collection periods, and entry methods were collated.

Results

Fifteen registries specific for HET were shortlisted with 136 affiliated peer-reviewed manuscripts.

Conclusion

There are few clinical registries specific to HET. Most of these are European, and the data collected are highly variable. Further research into their effectiveness is warranted. We note the absence of an Australian registry for all HET, which would provide potential health and economic gains. This review presents a unique opportunity to harmonize registry data for HET locally and further afield.

A transcriptional MAPK Pathway Activity Score (MPAS) is a clinically relevant biomarker in multiple cancer types

KRAS- and BRAF-mutant tumors are often dependent on MAPK signaling for proliferation and survival and thus sensitive to MAPK pathway inhibitors. However, clinical studies have shown that MEK inhibitors are not uniformly effective in these cancers indicating that mutational status of these oncogenes does not accurately capture MAPK pathway activity. A number of transcripts are regulated by this pathway and are recurrently identified in genome-based MAPK transcriptional signatures. To test whether the transcriptional output of only 10 of these targets could quantify MAPK pathway activity with potential predictive or prognostic clinical utility, we created a MAPK Pathway Activity Score (MPAS) derived from aggregated gene expression. In vitro, MPAS predicted sensitivity to MAPK inhibitors in multiple cell lines, comparable to or better than larger genome-based statistical models. Bridging in vitro studies and clinical samples, median MPAS from a given tumor type correlated with cobimetinib (MEK inhibitor) sensitivity of cancer cell lines originating from the same tissue type. Retrospective analyses of clinical datasets showed that MPAS was associated with the sensitivity of melanomas to vemurafenib (HR: 0.596) and negatively prognostic of overall or progression-free survival in both adjuvant and metastatic CRC (HR: 1.5 and 1.4), adrenal cancer (HR: 1.7), and HER2+ breast cancer (HR: 1.6). MPAS thus demonstrates potential clinical utility that warrants further exploration.

Investigation of N-cadherin/β-catenin expression in adrenocortical tumors

β-catenin is a multifunctional protein; it is a key component of the Wnt signaling, and it plays a central role in cadherin-based adhesions. Cadherin loss promotes tumorigenesis by releasing membrane-bound β-catenin, hence stimulating Wnt signaling. Cadherins seem to be involved in tumor development, but these findings are limited in adrenocortical tumors (ACTs). The objective of this study was to evaluate alterations in key components of cadherin/catenin adhesion system and of Wnt pathway. This study included eight normal adrenal samples (NA) and 95 ACT: 24 adrenocortical carcinomas (ACCs) and 71 adrenocortical adenomas (ACAs). β-catenin mutations were evaluated by sequencing, and β-catenin and cadherin (E-cadherin and N-cadherin) expression was analyzed by quantitative reverse transcription PCR (qRT-PCR) and by immunohistochemistry (IHC). We identified 18 genetic alterations in β-catenin gene. qRT-PCR showed overexpression of β-catenin in 50 % of ACC (12/24) and in 48 % of ACA (21/44). IHC data were in accordance with qRT-PCR results: 47 % of ACC (7/15) and 33 % of ACA (11/33) showed increased cytoplasmic or nuclear β-catenin accumulation. N-cadherin downregulation has been found in 83 % of ACC (20/24) and in 59 % of ACA (26/44). Similar results were obtained by IHC: N-cadherin downregulation was observed in 100 % (15/15) of ACC and in 55 % (18/33) of ACA. β-catenin overexpression together with the aberrant expression of N-cadherin may play important role in ACT tumorigenesis. The study of differentially expressed genes (such as N-cadherin and β-catenin) may enhance our understanding of the biology of ACT and may contribute to the discovery of new diagnostic and prognostic tools.

The PI3K/Akt Pathway in Tumors of Endocrine Tissues

The phosphatidylinositol 3-kinase (PI3K)/Akt pathway is a key driver in carcinogenesis. Defects in this pathway in human cancer syndromes such as Cowden's disease and Multiple Endocrine Neoplasia result in tumors of endocrine tissues, highlighting its importance in these cancer types. This review explores the growing evidence from multiple animal and in vitro models and from analysis of human tumors for the involvement of this pathway in the following: thyroid carcinoma subtypes, parathyroid carcinoma, pituitary tumors, adrenocortical carcinoma, phaeochromocytoma, neuroblastoma, and gastroenteropancreatic neuroendocrine tumors. While data are not always consistent, immunohistochemistry performed on human tumor tissue has been used alongside other techniques to demonstrate Akt overactivation. We review active Akt as a potential prognostic marker and the PI3K pathway as a therapeutic target in endocrine neoplasia.