# Exploring the Dynamic Interaction Between Pituitary Neuroendocrine Tumors (Pit-NETs) Cells and Their Angiogenic Microenvironment by Using the MIB1 Labeling Index, VEGF Expression and Digital Image Analysis

## TL;DR

This study explores how pituitary tumors and their surrounding blood vessels grow together, using digital analysis to link this growth to VEGF and tumor types.

## Contribution

The study introduces a novel comparison of tumor and endothelial cell proliferation using MIB1 and VEGF in pituitary tumors, revealing subtype-specific interactions.

## Key findings

- MIB1 LI in tumor and endothelial cells correlates with VEGF expression in pituitary tumors.
- PRL-secreting and non-functioning PitNETs show high MIB1 LI in stromal endothelial cells.
- Digital image analysis reveals heterogeneous VEGF and hormone profiles affecting tumor and endothelial proliferation.

## Abstract

One controversial issue in pituitary pathology is the simultaneous proliferation of PitNETs and endothelial cells. No previous studies have compared the MIB1 Labeling Index (MIB1 LI) of PitNETs and stromal endothelial compartments and its connection with VEGF protein and gene expression. Simultaneous PitNETs proliferation index assessment in tumor and endothelial cells is related to VEGF protein and gene expression, and by using the automated QuPath platform for digital image analysis (DIA), it can be determined whether this dual proliferation specifically characterizes certain PitNETs subtypes. A total of 109 PitNETs were immunostained for endothelial cells (CD34) and proliferation (MIB1). VEGF was assessed by using IHC and RNA scopes. QuPath_DIA measured hormone-dependent MIB1 nuclear expression in tumor and stromal endothelial cells. MIB1 LI correlated with VEGF_mRNA and protein expression. PRL-secreting and non-functioning PitNETs had a high MIB1 LI in stromal endothelial cells. MIB1-positive tumor cell (%MIB1 LI.T) and endothelial cell (%MIB1 LI.E) percentages were substantially correlated (p = 0.01). The profiles of VEGF and hormones significantly and heterogeneously impact the MIB1-LI of tumor and endothelial cells. Tumor–endothelial cell proliferative interaction is specific to PRL-secreting and non-functioning PitNETs. These findings suggest that digital analysis of MIB1 and VEGF expression may serve as a valuable tool for risk stratification in PitNETs.