A Novel Peptide that Disrupts the Lck-IP3R Protein-Protein Interaction Induces Widespread Cell Death in Leukemia and Lymphoma

Abstract

There is increasing evidence that the T-cell protein, Lck, is involved in the pathogenesis of chronic lymphocytic leukemia (CLL) as well as other leukemias and lymphomas. We previously discovered that Lck binds to domain 5 of inositol 1,4,5-trisphosphate receptors (IP 3 R) to regulate Ca 2+ homeostasis. Using bioinformatics, we targeted a region within domain 5 of IP 3 R-1 predicted to facilitate protein-protein interactions (PPIs). We generated a synthetic 21 amino acid peptide, KKRMDLVLELKNNASKLLLAI, which constitutes a domain 5 sub-domain (D5SD) of IP 3 R-1 that specifically binds Lck via its SH2 domain. With the addition of an HIV-TAT sequence to enable cell permeability of D5SD peptide, we observed wide-spread, Ca 2+ -dependent, cell killing of hematological cancer cells when the Lck-IP 3 R PPI was disrupted by TAT-D5SD. All cell lines and primary cells were sensitive to D5SD peptide, but malignant T-cells were less sensitive compared with B-cell or myeloid malignancies. Mining of RNA-seq data showed that LCK was expressed in primary diffuse large B-cell lymphoma (DLBCL) as well as acute myeloid leukemia (AML). In fact, LCK shows a similar pattern of expression as many well-characterized AML oncogenes and is part of a protein interactome that includes FLT3-ITD, Notch-1, and Kit. Consistent with these findings, our data suggest that the Lck-IP 3 R PPI may protect malignant hematopoietic cells from death. Importantly, TAT-D5SD showed no cytotoxicity in three different non-hematopoietic cell lines; thus its ability to induce cell death appears specific to hematopoietic cells. Together, these data show that a peptide designed to disrupt the Lck-IP 3 R PPI has a wide range of pre-clinical activity in leukemia and lymphoma.

Broadening the horizon: potential applications of CAR-T cells beyond current indications

“…In a subset of patients, CAR-T-cell therapy can offer a potential way to disease eradication ( 283 ). Additionally, recent approaches like the killing of CLL cells through targeting of the Lck-IP3R protein-protein interaction hint towards other innovative methods of immunotherapy targeting in CLL ( 284 ).…”