Cancer-associated fibroblasts regulate endothelial adhesion protein LPP to promote ovarian cancer chemoresistance
Cecilia S. Leung, … , Michael J. Birrer, Samuel C. Mok
Cecilia S. Leung, … , Michael J. Birrer, Samuel C. Mok
Published December 18, 2017
Citation Information: J Clin Invest. 2018;128(2):589-606. https://doi.org/10.1172/JCI95200.
View: Text | PDF
Research Article Cell biology Oncology Article has an altmetric score of 1

Cancer-associated fibroblasts regulate endothelial adhesion protein LPP to promote ovarian cancer chemoresistance

Abstract

The molecular mechanism by which cancer-associated fibroblasts (CAFs) confer chemoresistance in ovarian cancer is poorly understood. The purpose of the present study was to evaluate the roles of CAFs in modulating tumor vasculature, chemoresistance, and disease progression. Here, we found that CAFs upregulated the lipoma-preferred partner (LPP) gene in microvascular endothelial cells (MECs) and that LPP expression levels in intratumoral MECs correlated with survival and chemoresistance in patients with ovarian cancer. Mechanistically, LPP increased focal adhesion and stress fiber formation to promote endothelial cell motility and permeability. siRNA-mediated LPP silencing in ovarian tumor–bearing mice improved paclitaxel delivery to cancer cells by decreasing intratumoral microvessel leakiness. Further studies showed that CAFs regulate endothelial LPP via a calcium-dependent signaling pathway involving microfibrillar-associated protein 5 (MFAP5), focal adhesion kinase (FAK), ERK, and LPP. Thus, our findings suggest that targeting endothelial LPP enhances the efficacy of chemotherapy in ovarian cancer. Our data highlight the importance of CAF–endothelial cell crosstalk signaling in cancer chemoresistance and demonstrate the improved efficacy of using LPP-targeting siRNA in combination with cytotoxic drugs.

Authors

Cecilia S. Leung, Tsz-Lun Yeung, Kay-Pong Yip, Kwong-Kwok Wong, Samuel Y. Ho, Lingegowda S. Mangala, Anil K. Sood, Gabriel Lopez-Berestein, Jianting Sheng, Stephen T.C. Wong, Michael J. Birrer, Samuel C. Mok

×

Figure 6

LPP mediates the effect of MFAP5 on focal adhesions and stress fiber formation.

Options: View larger image (or click on image) Download as PowerPoint
LPP mediates the effect of MFAP5 on focal adhesions and stress fiber for...
(A) Immunofluorescence micrographs showing that LPP colocalized with key focal adhesion proteins including paxillin, FAK, and vinculin in the focal adhesions located at the cell membrane of the 2 MEC lines hMEC-1 and TIME, suggesting that LPP is a key component of the focal adhesions of endothelial cells. Red: focal adhesion proteins; green: LPP; blue: nuclei. (B) Immunofluorescence micrographs showing that TIME MECs transfected with LPP-targeting siRNA had fewer F-actin stress fibers and focal adhesions than did cells transfected with control scrambled siRNA, suggesting that LPP plays important roles in stress fiber and focal adhesion formation. Dot plot summarizes the data (mean ± SD; n = 10/treatment group; P values were determined by 2-tailed Student’s t test). Red: F-actin/vinculin; green: LPP; blue: nuclei. (C) Immunofluorescence micrographs showing that hMEC-1 and TIME MECs treated with 200 ng/ml recMFAP5 had more F-actin stress fibers and focal adhesions than did cells treated with PBS, suggesting that MFAP5 could increase stress fiber formation in endothelial cells. Red: F-actin; blue: nuclei. (D) Immunofluorescence micrographs showing that hMEC-1 and TIME MECs treated with 200 ng/ml recMFAP5 had more focal adhesions than did cells treated with PBS, suggesting that MFAP5 could increase focal adhesions in endothelial cells. Green: vinculin; blue: nuclei. (E) Immunofluorescence micrographs showing that recMFAP5-treated cells had markedly more stress fibers (red) attached to upregulated LPP (green) in focal adhesions on the cell membrane than did control cells. (F) Immunofluorescence micrographs showing that MFAP5-induced stress fiber formation and that focal adhesions were abrogated in TIME cells transfected with LPP-targeting siRNAs but not with the control scrambled siRNA, suggesting that LPP mediates the effect of MFAP5 in increasing stress fiber formation and focal adhesions. Red: F-actin/vinculin; green: LPP; blue: nuclei. Data are summarized in the dot plot (mean ± SD of 10 independent experiments; P values were determined by 2-tailed Student’s t test). Scale bars: 5 μm (A–F).