Poster Presentation 11th Asia-Pacific Congress of the International Society on Toxinology 2021

Toxins targeting voltage-gated potassium channel Kv1.3 as therapeutics for leukaemia (#124)

Raine S Mercedes 1 , Linda Blomster 1 , Mike Pennington 2 , Srikant Rangaraju 3 , Seow Theng Ong 4 , George Chandy 4 , Glenn F King 1 , Andrew A Walker 1
  1. Institute of Molecular Biosciences, St Lucia, Queensland, Australia
  2. AmbioPharm, North Augusta, South Carolina, USA
  3. Department of Neurology, Emory University School of Medicine, Atlanta, Georgia, USA
  4. Lee Kong Chian School of Medicine, Nanyang Technical University, Singapore

Currently, leukaemia is treated with multiple chemotherapeutic drugs, each of which has adverse side effects.  Consequently, new drugs are needed that kill or inhibit the growth of leukaemic cells while having a limited impact on non-cancer cells. Cell-surface receptors are commonly overexpressed in malignant tissues and are emerging as promising targets for selective tumour therapy. One such channel is Kv1.3, a potassium channel necessary for the proliferation and activation of lymphocytes. ShK, a peptide isolated from venom of the sea anemone Stichodactyla helianthus, inhibits Kv channels with low pM affinity. Previously, ShK analogues with enhanced specificity for Kv1.3 have been developed, transforming this peptide into a viable therapeutic for autoimmune diseases characterised by abnormal proliferation and activation of T lymphocytes. Since leukaemias also involve abnormal proliferation of lymphocytes, we hypothesised that Kv1.3 may be a viable therapeutic target in some leukaemic cells, either as a direct target or as a marker to direct peptide-drug conjugates.

To test the first hypothesis, we will use transcriptomics, electrophysiology, and proliferation assays to investigate KV1.3 expression and function in a range of leukaemic cells. Using subtype-specific inhibitors, we will determine whether KV1.3 channels are functional on the cell surface and if KV1.3 inhibitors affect proliferation. We will also compare channel expression to primary samples from patients who have leukaemia. Secondly, we hypothesised that it may be possible to target KV1.3 therapeutically if it is not necessary for proliferation of malignant lymphocytes but nevertheless present on their cell surface. To test this hypothesis, we produced a peptide-drug-conjugate, ShK-241-dexamethasone. This drug utilises an ShK analogue conjugated to the antileukaemic drug dexamethasone. We will test if this conjugate can inhibit the proliferation of leukaemic cell lines and characterise the cleavage of the hydrazide linker over time and a range of pH values.