VentX expression in tumor-associated macrophages promotes phagocytosis and immunity against pancreatic cancers
Yi Le, Hong Gao, William Richards, Lei Zhao, Ronald Bleday, Thomas Clancy, Zhenglun Zhu
Yi Le, Hong Gao, William Richards, Lei Zhao, Ronald Bleday, Thomas Clancy, Zhenglun Zhu
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Research Article Immunology

VentX expression in tumor-associated macrophages promotes phagocytosis and immunity against pancreatic cancers

Abstract

Pancreatic ductal adenocarcinoma (PDA) is a lethal malignancy that has no effective treatment. The tumor microenvironment (TME) of PDA employs a multitude of immune derangement strategies to protect PDA from immune elimination. Tumor-associated macrophages (TAMs) have been implicated in the pathogenesis of immune suppression of the PDA TME; however, its underlying mechanisms remained largely unknown. Using primary patient samples, our studies showed that, in comparison with macrophages isolated from normal pancreatic tissues, the phagocytosis activity of the PDA TAMs was significantly reduced. We found that the expression of homeobox protein VentX, a master regulator of macrophage plasticity, was significantly decreased in the PDA TAMs. We demonstrated that VentX was required for phagocytosis and that restoration of VentX expression in PDA TAMs promoted phagocytosis through the regulation of the signaling cascades involved in the process. Using an ex vivo culture model of primary human PDA, we showed that VentX-modulated TAMs transformed the PDA TME from a protumor milieu to an antitumor microenvironment by rectifying differentiation, proliferation, and activation of PDA-infiltrating immune cells. Using NSG-PDX models of primary human PDAs, we showed that VentX-modulated TAMs exerted strong inhibition on PDA tumorigenesis in vivo. Taken together, our data revealed a central mechanism underlying immune evasion of PDA and a potential novel venue to improve PDA prognosis.

Authors

Yi Le, Hong Gao, William Richards, Lei Zhao, Ronald Bleday, Thomas Clancy, Zhenglun Zhu

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Figure 3

VentX promotes TAM phagocytosis.

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VentX promotes TAM phagocytosis. (A) Quantification of phagocytosis acti...
(A) Quantification of phagocytosis activity of TAMs and control macrophages. Freshly isolated TAMs and control macrophages were incubated with 1 μM CellTrance Yellow–labeled Panc-1 cells. The rate of phagocytosis was determined by flow cytometry. Data are shown as the mean ± SD from 4 independent experiments. P < 0.01, paired Student’s t test. (B) VentX promotes TAM phagocytosis. TAMs were isolated and transfected with plasmids encoding GFP or GFP-VentX. The transfected TAMs were then incubated with 1 μM CellTrance Yellow–labeled cancer cells for 24 hours. The effects of the treatment were determined by phase-contrast and fluorescent microscopy (left) and flow cytometry analysis (right). Arrowheads indicated phagocytosed cancer cells. Scale Bar: 50 μM. The representative figure was shown. n = 3. (C) Phagocytosis and intracellular digestion of CellTrance Yellow–labeled Panc-1 cells. TAMs transfected with control GFP or GFP-VentX were incubated with CellTrance Yellow–labeled Panc-1 cells. Representative images of the phagocytosis were revealed by fluorescent microscopy after 24 hours (top) and 48 hours (bottom). Scale Bar: 20 μm. Quantification of phagocytotic cells was performed by measuring green fluorescence intensity after phagocytosis. The graph represents the pixel intensity of fluorescence. Data presented are mean ± SD. n = 3. **P < 0.01. At least 10 cells were scanned for each time point.