Biology subjects

Hein, L. E.

Publications and source records attributed to Hein, L. E..

3 recordsLinked to original sources

bioRxiv2025

cPLA2α Targeting to Exosomes Connects Nuclear Deformation to LTB4-Signaling During Neutrophil Chemotaxis

Efficient neutrophil chemotaxis requires the integration of mechanical forces and lipid-mediated signaling. While the signaling lipid leukotriene B4 (LTB4) reinforces cellular polarity, how mechanical cues regulate its production remains unclear. We now show that cytosolic phospholipase A2 (cPLA2), which is essential for the synthesis of LTB4, functions as a nuclear curvosensor. cPLA2 responds to nuclear constrictions by localizing to ceramide-rich inner nuclear membrane microdomains and incorporating onto the exofacial surface of nuclear envelope-derived exosomes. This unique topology enables localized LTB4 synthesis, which promotes myosin light chain II phosphorylation, and sustains polarity and directional persistence after constriction. In neutrophils squeezing through small constrictions, loss of cPLA2 impairs nuclear curvature sensing, exosomal LTB4 production, and post-constriction motility. These findings uncover a cPLA2-dependent mechano-chemical axis linking nuclear architecture to chemotactic efficiency and offering new strategies to modulate inflammatory responses.

cell biology↗

bioRxiv2023

TGF-β1 activates neutrophil signaling and gene expression but not migration

Tumor-associated neutrophils are found in many types of cancer and are often reported to contribute to negative outcomes. The presence of transforming growth factor-beta (TGF-{beta}) in the tumor microenvironment reportedly contributes to the skewing of neutrophils to a more pro-tumor phenotype. The effects of TGF-{beta} on neutrophil signaling and migration are, however, unclear. We sought to characterize TGF-{beta} signaling in both primary human neutrophils and the neutrophil-like cell line HL-60 and determine whether it directly induces neutrophil migration. We found that TGF-{beta}1 does not induce neutrophil chemotaxis in transwell or underagarose migration assays. TGF-{beta}1 does activate canonical signaling through SMAD3 and noncanonical signaling through ERK1/2 in neutrophils in a time-and dose-dependent manner. Additionally, TGF-{beta}1 present in the tumor-conditioned media (TCM) of invasive breast cancer cells results in SMAD3 activation. We discovered that TCM induces neutrophils to secrete leukotriene B4 (LTB4), which is a lipid mediator important for amplifying the range of neutrophil recruitment. However, TGF-{beta}1 alone does not induce secretion of LTB4. RNA-sequencing revealed that TGF-{beta}1 and TCM alter gene expression in HL-60 cells, including the mRNA levels of the pro-tumor oncostatin M (OSM) and vascular endothelial growth factor A (VEGFA). These new insights into the role and impact of TGF-{beta}1 on neutrophil signaling, migration, and gene expression have significant implications in the understanding of the changes in neutrophils that occur in the tumor microenvironment.

immunology↗

bioRxiv2021

TRIPLE-NEGATIVE BREAST CANCER CELLS RECRUIT NEUTROPHILS BY SECRETING TGF-β AND CXCR2 LIGANDS

Tumor associated neutrophils (TANs) are frequently detected in triple-negative breast cancer (TNBC). Recent studies also reveal the importance of neutrophils in promoting tumor progression and metastasis during breast cancer. However, the mechanisms regulating neutrophil trafficking to breast tumors are less clear. We sought to determine whether neutrophil trafficking to breast tumors is determined directly by the malignant potential of cancer cells. We found that tumor conditioned media (TCM) harvested from highly aggressive, metastatic TNBC cells induced a polarized morphology and robust neutrophil migration, while TCM derived from poorly aggressive estrogen receptor positive (ER+) breast cancer cells had no activity. In a three-dimensional (3D) type-I collagen matrix, neutrophils migrated toward TCM from aggressive breast cancer cells with increased velocity and directionality. Moreover, in a neutrophil-tumor spheroid co-culture system, neutrophils migrated with increased directionality towards spheroids generated from TNBC cells compared to ER+ cells. Based on these findings, we next sought to characterize the active factors secreted by TNBC cell lines. We found that TCM-induced neutrophil migration is dependent on tumor-derived chemokines, and screening TCM elution fractions based on their ability to induce polarized neutrophil morphology revealed the molecular weight of the active factors to be around 12 kDa. TCM from TNBC cell lines contained copious amounts of GRO (CXCL1/2/3) chemokines and TGF-{beta} cytokines compared to ER+ cell-derived TCM. TCM activity was inhibited by simultaneously blocking receptors specific to GRO chemokines and TGF-{beta}, while the activity remained intact in the presence of either single receptor inhibitor. Together, our findings establish a direct link between the malignant potential of breast cancer cells and their ability to induce neutrophil migration. Our study also uncovers a novel coordinated function of TGF-{beta} and GRO chemokines responsible for guiding neutrophil trafficking to the breast tumor.

immunology↗