Human colon mucosal biofilms from healthy or colon cancer hosts are carcinogenic
Sarah Tomkovich, … , Christian Jobin, Cynthia L. Sears
Sarah Tomkovich, … , Christian Jobin, Cynthia L. Sears
Published March 11, 2019
Citation Information: J Clin Invest. 2019;129(4):1699-1712. https://doi.org/10.1172/JCI124196.
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Research Article Microbiology Oncology

Human colon mucosal biofilms from healthy or colon cancer hosts are carcinogenic

Abstract

Mucus-invasive bacterial biofilms are identified on the colon mucosa of approximately 50% of colorectal cancer (CRC) patients and approximately 13% of healthy subjects. Here, we test the hypothesis that human colon biofilms comprise microbial communities that are carcinogenic in CRC mouse models. Homogenates of human biofilm-positive colon mucosa were prepared from tumor patients (tumor and paired normal tissues from surgical resections) or biofilm-positive biopsies from healthy individuals undergoing screening colonoscopy; homogenates of biofilm-negative colon biopsies from healthy individuals undergoing screening colonoscopy served as controls. After 12 weeks, biofilm-positive, but not biofilm-negative, human colon mucosal homogenates induced colon tumor formation in 3 mouse colon tumor models (germ-free ApcMinΔ850/+;Il10–/– or ApcMinΔ850/+ and specific pathogen–free ApcMinΔ716/+ mice). Remarkably, biofilm-positive communities from healthy colonoscopy biopsies induced colon inflammation and tumors similarly to biofilm-positive tumor tissues. By 1 week, biofilm-positive human tumor homogenates, but not healthy biopsies, displayed consistent bacterial mucus invasion and biofilm formation in mouse colons. 16S rRNA gene sequencing and RNA-Seq analyses identified compositional and functional microbiota differences between mice colonized with biofilm-positive and biofilm-negative communities. These results suggest human colon mucosal biofilms, whether from tumor hosts or healthy individuals undergoing screening colonoscopy, are carcinogenic in murine models of CRC.

Authors

Sarah Tomkovich, Christine M. Dejea, Kathryn Winglee, Julia L. Drewes, Liam Chung, Franck Housseau, Jillian L. Pope, Josee Gauthier, Xiaolun Sun, Marcus Mühlbauer, Xiuli Liu, Payam Fathi, Robert A. Anders, Sepideh Besharati, Ernesto Perez-Chanona, Ye Yang, Hua Ding, Xinqun Wu, Shaoguang Wu, James R. White, Raad Z. Gharaibeh, Anthony A. Fodor, Hao Wang, Drew M. Pardoll, Christian Jobin, Cynthia L. Sears

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Figure 1

Biofilm-positive human colon tissue inocula are carcinogenic in mouse models.

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Biofilm-positive human colon tissue inocula are carcinogenic in mouse mo...
(A and B) Colon tumor counts in GF (A) ApcMinΔ850/+;Il10–/– and ApcMinΔ850/+ and SPF (B) ApcMinΔ716/+ mice inoculated with biofilm-positive (BF+) human colon mucosal tissues or biofilm-negative (BF-bx) human colon mucosal tissues. n = 42 BF+ and n = 12 BF– ApcMinΔ850/+;Il10–/– and ApcMinΔ850/+ mice. Black circles represent mice analyzed 12 weeks after inoculation. White circles represent mice harvested 13–20 weeks after inoculation (n = 9 mice). n = 33 BF+ and n = 9 BF– for SPF ApcMinΔ716/+ mice. (C and D) Colon tumor counts in GF (C) ApcMinΔ850/+;Il10–/– and ApcMinΔ850/+ and SPF (D) ApcMinΔ716/+ mice inoculated with BF+ human mucosal tissues. For ApcMinΔ850/+;Il10–/– and ApcMinΔ850/+ mice, tumor counts from mice inoculated with BF+ human tumor (CRC patients) (BF+T, n = 25 mice), BF+ normal flanking tissues from CRC patients (BF+NF, n = 8 mice), BF+ colonoscopy mucosal biopsies from healthy subjects (BF+bx, n = 9 mice), and BF– colonoscopy mucosal biopsies from healthy subjects (BF-bx, n = 12 mice) are displayed. For SPF ApcMinΔ716/+ mice, n = 12 (BF+T); n = 8 (BF+NF); n = 13 (BF+bx); n = 9 (BF-bx). BF+ conditions do not differ statistically from each other. (E) Survival curve of BF-bx and BF+T reassociated GF ApcMinΔ850/+;Il10–/– mice over 12 weeks, analyzed by log-rank (Mantel-Cox) test and the log-rank test for trend (n = 9 mice per group). Inoculums for reassociation experiments were homogenates of proximal (PC) or distal colon (DC) tissues of mice associated with microbes from human BF-bx or BF+T mucosal tissues (see Methods). (F) Colon tumor counts in reassociated GF ApcMinΔ850/+;Il10–/– mice. n = 9 (BF-bx distal colon); n = 7 (BF+T PC); n = 5 (BF+T distal colon), since some BF+T reassociated mice did not survive to the 12-week end point. For A–D and F, data are displayed as mean ± SEM analyzed by Mann-Whitney U test. For C, D, and F, P < 0.0167 is considered statistically significant, based on Bonferroni’s correction for multiple comparisons.