# Rewired Neuroactive Ligand-Receptor Signaling Confers Adaptive Resistance to BCL-2 Inhibition in AML

## TL;DR

This study reveals that AML cells develop resistance to venetoclax by rewiring a neuroactive signaling pathway, offering new treatment strategies.

## Contribution

The study identifies the NLRI pathway and the gene CHRNB4 as key drivers of resistance to BCL-2 inhibitors in AML.

## Key findings

- Venetoclax-resistant AML cells show enhanced proliferation and tumorigenicity in mice.
- The NLRI pathway is a key vulnerability in resistant cells, with CHRNB4 being significantly downregulated.
- Low CHRNB4 expression correlates with poor patient survival and reduced venetoclax response in AML.

## Abstract

A major challenge in treating AML with the BCL-2 inhibitor venetoclax is the frequent development of drug resistance, which diminishes therapeutic efficacy and leads to patient death. The fundamental mechanisms underlying this resistance are not fully understood. Here, we established venetoclax-resistant cell models of AML that propagate even when the levels of BCL-2, MCL-1, cleaved PARP, and cleaved caspase-9 are reduced, suggesting a BCL-2-independent resistance mechanism. Compared to sensitive cells, resistant Kasumi-1 (VENK) and MV4-11 (VENM) cells exhibit enhanced proliferation both in vitro and in vivo, forming larger and more numerous spheroids and colonies, and displaying higher tumorigenicity in mice. RNA sequencing and KEGG pathway analysis identified the neuroactive ligand–receptor interaction (NLRI) pathway as a key vulnerability in both resistant cell lines. While the NLRI pathway contains numerous altered genes, CHRNB4 is the only gene commonly shared and significantly downregulated in both VENK and VENM cells and tumors. Enforced expression of CHRNB4 in resistant cells with low basal expression impaired cell adhesion and colony formation. Clinically, CHRNB4 downregulation is associated with poor AML patient overall survival and predicts a diminished response to venetoclax treatment. This study identifies the NLRI pathway as a crucial vulnerability in venetoclax resistance and unveils CHRNB4 as a promising predictive biomarker for treatment response. These results suggest that targeting the NLRI pathway represents a novel strategy for developing next-generation therapies to improve the poor outcomes of current combination treatments.