# The lipid phosphatase INPP4B controls pancreatic cancer cell migration and invasion by regulating fibronectin exocytosis

## TL;DR

This study shows how the lipid phosphatase INPP4B promotes aggressive behavior in pancreatic cancer by controlling fibronectin exocytosis and cell migration.

## Contribution

The study reveals a novel mechanism by which INPP4B regulates fibronectin exocytosis and cancer cell invasion in pancreatic ductal adenocarcinoma.

## Key findings

- INPP4B promotes fibronectin 1 secretion via TRPML1-dependent lysosomal exocytosis.
- FN1 exocytosis is essential for INPP4B's role in F-actin formation and cell migration.
- The INPP4B–TRPML1–FN1 axis contributes to PDAC aggressiveness and is a potential therapeutic target.

## Abstract

Increased expression of inositol polyphosphate 4-phosphatase, type II (INPP4B) correlates with aggressive phenotypes in pancreatic ductal adenocarcinoma (PDAC). Although prior studies have linked INPP4B to lysosome positioning, exocytosis, and enhanced cell migration and invasion in PDAC, the specific mechanisms underlying these processes remain unclear. In this study, we demonstrate that INPP4B promotes fibronectin 1 (FN1) secretion via transient receptor potential cation channel mucolipin subfamily member 1–dependent lysosomal exocytosis. In addition, we show that INPP4B-mediated regulation of F-actin formation, focal adhesion kinase activation, and increased cell migration and invasion depend on FN1 exocytosis. These findings underscore the INPP4B–transient receptor potential cation channel mucolipin subfamily member 1–FN1 axis as a critical contributor to PDAC aggressiveness and identify it as a promising candidate for the development of new therapeutic strategies.