Interleukin-6 mediates resistance to PI3K-pathway\u2013targeted therapy in lymphoma

Joo Hyun Kim,Won Seog Kim,Chaehwa Park

doi:10.1186/s12885-019-6057-7

Joo Hyun Kim, Won Seog Kim + Show 1 more

Open Access

https://doi.org/10.1186/s12885-019-6057-7

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Abstract

BackgroundThe phosphoinositol 3-kinase (PI3K) pathway is associated with poor prognosis of hematologic malignancies, providing a strong rationale for the use of PI3K inhibitors in the treatment of malignant lymphoma. However, development of resistance limits the use of PI3K inhibitors in lymphoma patients.MethodsWe established copanlisib (pan-PI3K inhibitor)-resistant B-cell lymphoma and duvelisib (PI3Kδ and -γ inhibitor)-resistant T-cell lymphoma cell lines. The cytokine array and the phospho-kinase array were used to identify up-regulated proteins in the resistant cells. Cytokine expression and phospho-kinase levels were examined by ELISA and Western blot analysis, respectively. Cell proliferation capabilities were measured by using CCK-8 kit and colony formation assay. The effects of inhibitors on apoptosis were detected using an Annexin V-FITC Apoptosis Detection Kit and a flow cytometry system. The underlying mechanisms were studied by transfecting recombinant plasmids or siRNA into lymphoma cell lines. Cells were transiently transfected using the Amaxa electroporation system. We evaluated the effects of PI3K inhibitor alone and in combination with JAK inhibitor (BSK805) on lymphoma proliferation and signaling pathway activation.ResultsCytokine arrays revealed upregulation of interleukin (IL)-6 in both copanlisib- and duvelisib-resistant cell lines. Phosphorylated STAT5, AKT, p70S6K and MAPK were increased in copanlisib-resistant B-cell lymphoma cells, whereas phosphorylated STAT3 and NF-κB were increased in duvelisib-resistant T cell lymphoma cells. Conversely, depletion of IL-6 sensitized both resistant cell lines, and led to downregulation of phosphorylated STAT3 and STAT5 in copanlisib- and duvelisib-resistant cells, respectively. Moreover, combined treatment with a JAK inhibitor (BSK805) and a PI3K inhibitor circumvented the acquired resistance to PI3K inhibitors in lymphoma, and concurrent inhibition of the activated pathways produced combined effects.ConclusionsIL-6–induced STAT3 or STAT5 activation is a critical mechanism underlying PI3K inhibitor resistance in lymphoma, supporting the utility of IL-6 as an effective biomarker to predict therapeutic response to PI3K inhibitors.

Highlights

The phosphoinositol 3-kinase (PI3K) pathway is associated with poor prognosis of hematologic malignancies, providing a strong rationale for the use of PI3K inhibitors in the treatment of malignant lymphoma
BJAB, OCI-Ly1 and U2932 B-cell lymphoma cells were sensitive to copanlisib, whereas Jurkat, HUT78 and HH T-cell lymphoma cell lines were found to be sensitive to duvelisib (Fig. 1a)
To confirm that PI3K inhibitors suppressed the growth of the analyzed lymphoma cell lines, we evaluated the cell growth percentage by comparing viability at day 0 with that at day 3

Summary

Introduction

The phosphoinositol 3-kinase (PI3K) pathway is associated with poor prognosis of hematologic malignancies, providing a strong rationale for the use of PI3K inhibitors in the treatment of malignant lymphoma. Development of resistance limits the use of PI3K inhibitors in lymphoma patients. The phosphoinositide 3-kinase (PI3K) signaling pathway is frequently activated in many cancers and. Clinical studies of duvelisib in indolent non-Hodgkin lymphoma and chronic lymphocytic leukemia (CLL) have shown effective clinical activity [13, 14]. It was recently shown that the PI3K inhibitors, copanlisib and duvelisib, are effective against DLBCL and relapsed/refractory T-cell lymphoma, respectively [17, 18]. IL-6 modulates effector cytokine production by B and T cells [19], and plays an important role in activating several pro-oncogenic signaling pathways in cancer [20, 21]

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