Therapeutic Restoration of Cholangiocyte Primary Cilia via Microbiota-Derived Butyrate: A Novel Approach for Bile Duct Cancer

/Abstract Cholangiocarcinoma (CCA) is an aggressive tumor with the urgent need of better therapeutical approaches. Our research has established that primary cilia, critical sensory organelles in cholangiocytes, are frequently lost or malformed in CCA, contributing to disease progression. Our findings also show that dysfunctional or experimental elimination of cilia transforms a normal cell into a hyperproliferative one. We also found that pathologic overexpression of SIRT1 leads to ciliary loss. Importantly, our preliminary data indicate that butyrate, a gut microbiota-derived short-chain fatty acid (SCFA) and a known SIRT1 inhibitor, restores ciliary expression and reduces tumor cell proliferation. Dietary fibers are indigestible polysaccharide digested by bacterial fermentation in the gastrointestinal tract until arrival to the colon, resulting in the formation of SCFAs including butyrate. Thus, presence of fiber diet and specific bacterial type may favor the production of the SCFAs, leading to different changes in the gut and distal organs. Our long-term goals are to understand the pathogenesis of the cholangiociliopathies and to develop new therapies for its treatment. Our overall objective for this proposal is to explore the novel hypothesis that dietary interventions that promote bacterial butyrate formation in the gut maintain and/or rescue ciliary expression in cholangiocyte to decrease disease progression. Our rationale is based on our previous findings and preliminary in vitro data showing that; (i) experimental deciliation of cholangiocytes induces cell proliferation and migration; (ii) overexpression of deacetylases, including SIRT1, are responsible for decreased ciliary expression; (iii) SIRT1 inhibition rescues primary cilia expression; and (iv) Butyrate inhibits SIRT1 activity and promotes ciliary expression decreasing cell proliferation. Thus, we propose here the novel CENTRAL HYPOTHESES that increasing butyrate levels in the gut (through fiber supplementation and/or probiotic microbiota modulation) will restore cholangiocyte primary cilia and reprogram tumor cell behavior, thereby slowing CCA progression. To test these central hypotheses, we propose two Specific Aims. In Aim 1 (Therapeutic Aim), we test the hypothesis that butyrate produced via fiber fermentation by gut bacteria, or delivered as oral tributyrin, can reduce CCA tumor growth and progression by promoting cilia-dependent tumor cell cycle arrest and cell death in rodent models of CCA. In Aim 2 (Mechanistic Aim) we Determine the mechanisms by which SCFAs restore primary cilia and alter tumor cell behavior, independent of Aim 1. Impact: These experiments will uncover novel and generalizable information on the fundamental mechanisms of therapeutic ciliary-restoration by the gut microbiota and dietary manipulations for CCA that may be applicable to other tumors and ciliopathies and have translational potential to improve outcomes for patients. Project Number: 1R21CA310158-01 | Fiscal Year: 2026 | NIH Institute/Center: National Cancer Institute (NCI) | Principal Investigator: Sergio Gradilone | Institution: UNIVERSITY OF MINNESOTA, MINNEAPOLIS, MN | Award Amount: $408,829 | Activity Code: R21 | Study Section: Special Emphasis Panel[ZRG1 KUDS-S (04)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11317892