Labaf, M. | bioRxiv Science

bioRxiv2025

FOXJ1 mediates taxane resistance through regulation of microtubule dynamics

Docetaxel is the first-line chemotherapy for metastatic castration-resistant prostate cancer (PC), but clinically meaningful mechanisms of resistance remain to be established. We generated an in vivo model of docetaxel resistance using castration-resistant patient-derived xenografts and found increased expression of genes that drive development of multiciliated cells, including FOXJ1 and its effector genes, many of which regulate ciliary microtubules (MTs). Mechanistically, FOXJ1 overexpression conferred docetaxel resistance in vitro and in vivo, which was associated with decreased docetaxel-mediated MT bundling. Overexpression of a MT-associated FOXJ1-regulated gene (TPPP3) had similar effects. Conversely, FOXJ1 knockdown impaired basal MT function, enhanced taxane binding to MTs, and increased docetaxel sensitivity. These results establish mechanistic causality between the FOXJ1 signaling axis, MT biology, and taxane resistance. Clinically, FOXJ1 gene amplification was increased in taxane-treated PC patients. Moreover, in the CHAARTED clinical trial of docetaxel combined with androgen deprivation for metastatic PC, higher baseline FOXJ1 was predictive of decreased survival in PC patients treated with docetaxel, further supporting clinical relevance. Together these findings identify a previously unrecognized clinically impactful mechanism of taxane resistance whose exploitation could stratify patients that will not benefit from taxane treatment. Statement of SignificanceThe early use of docetaxel in combination with androgen receptor targeted therapy can enhance survival in a subset of PC. This study indicates that increased FOXJ1 is predictive of tumors that will not benefit from docetaxel, and that agents targeting FOXJ1 or downstream effectors may enhance taxane responses and improve patient outcomes.

cancer biology↗

bioRxiv2024

Drug resistant pancreatic cancer cells exhibit altered biophysical interactions with stromal fibroblasts in imaging studies of 3D co-culture models

Interactions between tumor and stromal cells are well known to play a prominent roles in progression of pancreatic ductal adenocarcinoma (PDAC). As knowledge of stromal crosstalk in PDAC has evolved, it has become clear that cancer associated fibroblasts can play both tumor promoting and tumor suppressive roles through a combination of paracrine crosstalk and juxtacrine interactions involving direct physical contact. Another major contributor to dismal survival statistics for PDAC is development of resistance to chemotherapy drugs. Though less is known about how the acquisition of chemoresistance impacts upon tumor-stromal crosstalk. Here, we use 3D co-culture geometries to recapitulate juxtacrine interactions between epithelial and stromal cells. In particular, extracellular matrix (ECM) overlay cultures in which stromal cells (pancreatic stellate cells, or normal human fibroblasts) are placed adjacent to PDAC cells (PANC1), result in direct heterotypic cell adhesions accompanied by dramatic fibroblast contractility which leads to highly condensed macroscopic multicellular aggregates as detected using particle image velocimetry (PIV) analysis to quantify cell velocities over the course of time lapse movie sequences. To investigate how drug resistance impacts these juxtacrine interactions we contrast cultures in which PANC1 are substituted with a drug resistant subline (PANC1-OR) previously established in our lab. We find that heterotypic cell-cell interactions are highly suppressed in drug-resistant cells relative to the parental PANC1 cells. To investigate further we conduct RNA-seq and bioinformatics analysis to identify differential gene expression in PANC1 and PANC1-OR, which shows that negative regulation of cell adhesion molecules, consistent with increased epithelial mesenchymal transition (EMT), is also consistent with loss of hetrotypic cell-cell contact necessary for the contractile behavior observed in drug naive cultures. Overall these findings elucidate the role of drug-resistance in inhibiting an avenue of stromal crosstalk which is associated with tumor suppression and also help to establish cell culture conditions useful for further mechanistic investigation.

biophysics↗