CX-4945 Induces Methuosis in Cholangiocarcinoma Cell Lines by a CK2-Independent Mechanism.

Jomnarong Lertsuwan,Jutamaad Satayavivad,Philip Kitchen,Kornkamon Lertsuwan,Anyaporn Sawasdichai,Nathapol Tasnawijitwong,Ka Lee,Padma-Sheela Jayaraman,Simon Afford,Kevin Gaston

doi:10.3390/cancers10090283

Abstract

Cholangiocarcinoma is a disease with a poor prognosis and increasing incidence and hence there is a pressing unmet clinical need for new adjuvant treatments. Protein kinase CK2 (previously casein kinase II) is a ubiquitously expressed protein kinase that is up-regulated in multiple cancer cell types. The inhibition of CK2 activity using CX-4945 (Silmitasertib) has been proposed as a novel treatment in multiple disease settings including cholangiocarcinoma. Here, we show that CX-4945 inhibited the proliferation of cholangiocarcinoma cell lines in vitro. Moreover, CX-4945 treatment induced the formation of cytosolic vacuoles in cholangiocarcinoma cell lines and other cancer cell lines. The vacuoles contained extracellular fluid and had neutral pH, features characteristic of methuosis. In contrast, simultaneous knockdown of both the α and α′ catalytic subunits of protein kinase CK2 using small interfering RNA (siRNA) had little or no effect on the proliferation of cholangiocarcinoma cell lines and failed to induce the vacuole formation. Surprisingly, low doses of CX-4945 increased the invasive properties of cholangiocarcinoma cells due to an upregulation of matrix metallopeptidase 7 (MMP-7), while the knockdown of CK2 inhibited cell invasion. Our data suggest that CX-4945 inhibits cell proliferation and induces cell death via CK2-independent pathways. Moreover, the increase in cell invasion brought about by CX-4945 treatment suggests that this drug might increase tumor invasion in clinical settings.

Highlights

Cholangiocarcinoma (CCA) is a cancer of bile duct epithelia thought to arise as a result of chronic inflammation of the liver and bile ducts
CCA cells treated with 10 and 15 μM CX-4945 did not increase in number over 5 days in culture (Figure 1b), and higher doses of CX-4945 (25 and 50 μM)
To determine whether the reduction in cell number is accompanied by reduced cell proliferation, we examined the effects of CX-4945 on 5-bromo-20 -deoxyuridine (BrdU) incorporation

Summary

Introduction

Cholangiocarcinoma (CCA) is a cancer of bile duct epithelia thought to arise as a result of chronic inflammation of the liver and bile ducts. The incidence of CCA has increased gradually worldwide during the last three decades [1,2,3,4]. The incidence of this disease is highest in Southeast Asia [5]. Approximately 70% of intrahepatic cholangiocarcinoma patients have a recurrence of disease post-surgery [10]. Adjuvant capecitabine treatment is effective post-surgery but median survival is only around four years [11]. There is an urgent unmet clinical need for new adjuvant therapies that could prevent recurrence as well as for new and effective second line drug treatments

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Discussion

Conclusion