Tumor cell-selective apoptosis induction through targeting of KV10.1 via bifunctional TRAIL antibody

Franziska Hartung,Walter Stühmer,Luis A Pardo

doi:10.1186/1476-4598-10-109

Franziska Hartung, Walter Stühmer + Show 1 more

Open Access

https://doi.org/10.1186/1476-4598-10-109

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Abstract

BackgroundThe search for strategies to target ion channels for therapeutic applications has become of increasing interest. Especially, the potassium channel KV10.1 (Ether-á-go-go) is attractive as target since this surface protein is virtually not detected in normal tissue outside the central nervous system, but is expressed in approximately 70% of tumors from different origins.MethodsWe designed a single-chain antibody against an extracellular region of KV10.1 (scFv62) and fused it to the human soluble TRAIL. The KV10.1-specific scFv62 antibody -TRAIL fusion protein was expressed in CHO-K1 cells, purified by chromatography and tested for biological activity.ResultsProstate cancer cells, either positive or negative for KV10.1 were treated with the purified construct. After sensitization with cytotoxic drugs, scFv62-TRAIL induced apoptosis only in KV10.1-positive cancer cells, but not in non-tumor cells, nor in tumor cells lacking KV10.1 expression. In co-cultures with KV10.1-positive cancer cells the fusion protein also induced apoptosis in bystander KV10.1-negative cancer cells, while normal prostate epithelial cells were not affected when present as bystander.ConclusionsKV10.1 represents a novel therapeutic target for cancer. We could design a strategy that selectively kills tumor cells based on a KV10.1-specific antibody.

Highlights

The search for strategies to target ion channels for therapeutic applications has become of increasing interest
Construction, expression and purification of scFv62-tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) The construction of the single-chain antibody against the pore of KV10.1 fused to alkaline phosphatase has been described before [29]
The sequence of alkaline phosphatase was removed from the scFv62-AP construct and TRAIL was cloned from the pEGFP-TRAIL vector [33] together with a peptide linker initially into a bacterial expression plasmid and transformed in the E.coli over-expression strain BL21

Summary

Introduction

The search for strategies to target ion channels for therapeutic applications has become of increasing interest. The potassium channel KV10.1 (Ether-á-go-go) is attractive as target since this surface protein is virtually not detected in normal tissue outside the central nervous system, but is expressed in approximately 70% of tumors from different origins. Clonal selection induces the development of apoptosis-resistant, androgenindependent cells, were therapeutic prospects are relatively poor [2]. Antibodies have become essential in the diagnostic and therapeutic field and form one of the biggest classes of new drugs approved for the treatment of cancer in the last decade [3]. The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising candidate for the design of bifunctional antibodies. Binding of the trimeric TRAIL to its receptors TRAIL-R1 and TRAIL-R2 induces caspase activation and apoptosis [4], either through the extrinsic pathway alone or recruiting the intrinsic apoptotic pathway [5]. TRAILR2 has a higher binding affinity for TRAIL, resulting in predominant binding of TRAIL to TRAIL-R2 over TRAILR1 [7]

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