Adenosine Inhibits Cholangiocarcinoma by a Concurrent Activation of AMPK and mTORC1 Signaling Pathways

Background/Aim: Cholangiocarcinoma (CCA) is a highly aggressive cancer for which current chemotherapies offer limited effectiveness. However, recent research suggests a promising new approach using adenosine. Studies have shown that adenosine can inhibit CCA cell growth while having minimal harmful effects on immortalized cholangiocytes (imCho). This particular study delved deeper into these findings, investigating the specific effects of adenosine on CCA and imCho to better understand its therapeutic potential against this disease.

Materials and Methods: Cell growth was examined using the MTT assay. Cell invasion was examined using the transwell assay. Cell death was evaluated using flow cytometry. Protein levels were examined using western blot analysis. Animal experiment was performed in Balb/cAJcl-Nu mice.

Results: Adenosine demonstrated differential effects on CCA cells compared to imCho. Specifically, adenosine induced endoplasmic reticulum (ER) stress in CCA cells but not in imCho. When combined with hydroxychloroquine (an autophagy inhibitor), apoptosis was greatly enhanced in CCA cells. This combination exhibited a more pronounced deleterious effect on CCA cells than on imCho cells, suggesting a potential for selective targeting. While adenosine alone demonstrated the ability to slow CCA growth in vitro, it did not induce apoptosis in this setting. However, in vivo tumor xenograft studies revealed comparable tumor sizes between adenosine monotherapy and the adenosine-hydroxychloroquine combination. Notably, the combination group exhibited a higher number of apoptotic cells. Further investigation into the molecular mechanisms revealed that adenosine activated both AMPK and mTORC1 signaling pathways. Crucially, the mTORC1 pathway was found to be essential for adenosine’s ability to inhibit CCA cell growth and invasion.

Conclusion: A co-activation of AMPK and mTORC1 signaling pathways in CCA cells after adenosine treatment. Both pathways are necessary for adenosine to inhibit CCA cell growth and invasion.