Bacterial cancer therapy in autochthonous colorectal cancer affects tumor growth and metabolic landscape
Gillian M. Mackie, … , Hiroshi Ohno, Kendle M. Maslowski
Gillian M. Mackie, … , Hiroshi Ohno, Kendle M. Maslowski
Published October 28, 2021
Citation Information: JCI Insight. 2021;6(23):e139900. https://doi.org/10.1172/jci.insight.139900.
View: Text | PDF
Research Article Gastroenterology

Bacterial cancer therapy in autochthonous colorectal cancer affects tumor growth and metabolic landscape

Abstract

Bacterial cancer therapy (BCT) shows great promise for treatment of solid tumors, yet basic mechanisms of bacterial-induced tumor suppression remain undefined. Attenuated strains of Salmonella enterica serovar Typhimurium (STm) have commonly been used in mouse models of BCT in xenograft and orthotopic transplant cancer models. We aimed to better understand the tumor epithelium–targeted mechanisms of BCT by using autochthonous mouse models of intestinal cancer and tumor organoid cultures to assess the effectiveness and consequences of oral treatment with aromatase A–deficient STm (STmΔaroA). STmΔaroA delivered by oral gavage significantly reduced tumor burden and tumor load in both a colitis-associated colorectal cancer (CAC) model and in a spontaneous Apcmin/+ intestinal cancer model. STmΔaroA colonization of tumors caused alterations in transcription of mRNAs associated with tumor stemness, epithelial-mesenchymal transition, and cell cycle. Metabolomic analysis of tumors demonstrated alteration in the metabolic environment of STmΔaroA-treated tumors, suggesting that STmΔaroA imposes metabolic competition on the tumor. Use of tumor organoid cultures in vitro recapitulated effects seen on tumor stemness, mesenchymal markers, and altered metabolome. Furthermore, live STmΔaroA was required, demonstrating active mechanisms including metabolite usage. We have demonstrated that oral BCT is efficacious in autochthonous intestinal cancer models, that BCT imposes metabolic competition, and that BCT has direct effects on the tumor epithelium affecting tumor stem cells.

Authors

Gillian M. Mackie, Alastair Copland, Masumi Takahashi, Yumiko Nakanishi, Isabel Everard, Tamotsu Kato, Hirotsugu Oda, Takashi Kanaya, Hiroshi Ohno, Kendle M. Maslowski

×

Figure 7

STmΔaroA treatment affects tumor organoid stem–forming capacity.

Options: View larger image (or click on image) Download as PowerPoint
STmΔaroA treatment affects tumor organoid stem–forming capacity. (A) Or...
(A) Organoids were infected with STmΔaroA (or control) as in Figure 6 for 24 hours. They were then dissociated into a single cell suspension. An equal number was then reseeded into Matrigel and passaged weekly at an equal density for 3 weeks. MTT assay was performed at the indicated day. Representative images are shown below for the indicated days. Scale bars: 500 μm. Each point indicates an independent well. Two-way Students T-test performed. Representative of 2 experiments, data shown from Apcmin/+,SI tumor line. (B) Measurement of LDH in the cell culture supernatant after 24 hours of infection. Data shown as percentage of cell death compared with wells treated with cell lysis solution. Each data point indicates an independent well. Data are representative of 3 experiments. (C) Active caspase 3 assessed by a plate-based colorimetric assay on organoids infected as in B, with the addition of a pan-caspase inhibitor or staurosporine (STS) alone. Each point is an individual well. One-way ANOVA with Dunnett’s multiple-comparison test. Representative images to the right. Scale bar: 500 μm. Data are representative of 2 independent experiments and shown from Apcmin/+,SI tumor line. (D and E) Tumor organoids derived from Lgr5-GFP reporter mice induced with CAC were infected with mCherry-expressing STmΔaroA for 24 hours, as outlined. Organoids were dissociated into single cells, stained with a live/dead marker, and analyzed by flow cytometry. The percentage of cells that are infected (mCherry+) in the live or dead cell gate (D) and the percentage of cells from the mCherry+ gate that are EpCAM+Lgr5– or EpCAM+Lgr5+ (E) are shown. Data are pooled from 2 independent experiments, and each point is an average from 2 wells. Data are shown as mean ± SD.