Short-Chain Fatty Acid Butyrate Induces Cilia Formation and Potentiates the Effects of HDAC6 Inhibitors in Cholangiocarcinoma Cells.

Kishor Pant,Seth Richard,Sergio A Gradilone

doi:10.3389/fcell.2021.809382

Abstract

Cholangiocarcinoma (CCA) is a deadly form of liver cancer with limited therapeutic approaches. The pathogenesis of CCA involves the loss of primary cilia in cholangiocytes, an important organelle that regulates several key cellular functions including the regulation of cell polarity, growth, and differentiation, by a mechanism involving increased expression of deacetylases like HDAC6 and SIRT1. Therefore, cilia restoration may represent an alternative and novel therapeutic approach against CCA. Butyrate is produced by bacterial fermentation of fibers in the intestine and has been shown to inhibit SIRT1, showing antitumor effects on various cancers. Herein, we investigated the role of butyrate on CCA cell proliferation, migration, and EMT and evaluated the synergistic effects with specific HDAC6 inhibition. When CCA cells, including HuCCT1 and KMCH, were treated with butyrate, the cilia formation and acetylated-tubulin levels were increased, while no significant effects were observed in normal human cholangiocytes. Butyrate treatment also depicted reduced cell proliferation in HuCCT1 and KMCH cells, but on the other hand, it affected cell growth of the normal cholangiocytes only at high concentrations. In HuCCT1 cells, spheroid formation and cell migration were also halted by butyrate treatment. Furthermore, we found that butyrate augmented the previously described effects of HDAC6 inhibitors on CCA cell proliferation and migration by reducing the expression of CD44, cyclin D1, PCNA, Zeb1, and Vimentin. In summary, butyrate targets cancer cell growth and migration and enhances the anti-cancer effects of HDAC6 inhibitors in CCA cells, suggesting that butyrate may have therapeutic effects in CCA and other ciliopathies.

Highlights

Malignancy of the bile ducts, called cholangiocarcinoma (CCA), is a deadly form of liver cancer
We have previously shown that inhibition of SIRT1 and HDAC6 induces cilia formation and inhibits cell growth in CCA cells (Gradilone et al, 2013; Pant et al, 2021)
We found that butyrate treatment does not significantly affect SIRT1 protein expression and levels of Ac-α-tubulin in H69 cells (Figure 1J), but decreased SIRT1 expression and increased Ac-α-tubulin levels in HuCCT1 and KMCH cells in a concentration-dependent manner (Figures 1K,L)

Summary

Introduction

Malignancy of the bile ducts, called cholangiocarcinoma (CCA), is a deadly form of liver cancer. CCA is the second most common primary liver malignancy in adults, accounting for 15–20% of cases. It is a rare form of cancer in the United States but occurs at high rates in Asian countries mainly in Thailand, China, and India. The pathogenesis of CCA, as well as in other tumors, seems to involve the loss of primary cilia in cholangiocytes (Gradilone et al, 2013; Razumilava et al, 2014; Gradilone et al, 2017; MerinoAzpitarte et al, 2017; Mansini et al, 2018, 2019; Banales et al, 2020; Pant et al, 2020; Peixoto et al, 2020a, 2020b). Cilia restoration could be advantageous as an effective therapeutic approach against CCA

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Conclusion