Abstract 2637: Examining the function of the serine protease, Granzyme B, in ALK-positive, anaplastic large cell lymphoma.

Abstract

Abstract Anaplastic lymphoma kinase-positive, anaplastic large cell lymphoma (ALK+ ALCL) is an aggressive non-Hodgkin lymphoma (NHL) that accounts for 10-20% of childhood NHL. The normal cellular counterpart of this malignancy is thought to be an activated T lymphocyte, based on the observations that tumour cells often exhibit clonal T cell receptor gene rearrangements and possess cytotoxic granules containing proteins such as Perforin and serine protease, Granzyme B (GzB). Chromosomal translocations involving the ALK tyrosine kinase gene are the defining characteristic of this lymphoma. These translocations result in the expression of oncogenic ALK fusion proteins (e.g. NPM-ALK), which are able initiate signalling events crucial for the pathogenesis of ALK+ ALCL. We have previously found that signalling initiated by NPM-ALK and the JunB transcription factor contributes to the phenotypic characteristics of ALK+ ALCL by promoting the expression of GzB. GzB is best characterized for its role as an effector molecule used by cytotoxic T lymphocytes and natural killer cells to kill virally infected and transformed cells; however, GzB can also be secreted from different cell types and has the ability to cleave extracellular matrix (ECM) proteins. Furthermore, GzB is expressed in some urothelial and bladder cancers and was shown to promote invasion of bladder cancer cell lines in vitro and GzB expression is associated with a greater level of tumour invasiveness in patients with urothelial cancer. Given these findings, and that NPM-ALK signalling promotes GzB expression in ALK+ ALCL, we hypothesized that GzB plays a role in the pathogenesis of this malignancy by influencing the interaction of ALK+ ALCL cells with ECM proteins. In this regard we hypothesize that GzB released by ALK+ ALCL cells can cleave ECM proteins which may affect the ability of ALK+ ALCL cells to adhere to these ECM proteins and may also promote tumour cell invasion. We have found that ALK+ ALCL cell lines express enzymatically active GzB that has the ability to cleave the ECM proteins, fibronectin and vitronectin. Furthermore, we have found that these cells also release active GzB and we are now examining if GzB expression influences adhesion of ALK+ ALCL cell lines to ECM proteins and whether GzB promotes the invasion of ALK+ ALCL cell lines in vitro. This work will determine if the expression of GzB is more than just a phenotypic characteristic of ALK+ ALCL, and whether this protein may contribute to the invasive potential of this lymphoma. If so, these findings may help to explain why tumour cells are found to be widely disseminated in ALK+ ALCL patients and murine xenograft models. Citation Format: Joel D. Pearson, Katelynn Rowe, Kayla Thew, Jing xi Zhang, Spencer Freeman, Robert J. Ingham. Examining the function of the serine protease, Granzyme B, in ALK-positive, anaplastic large cell lymphoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2637. doi:10.1158/1538-7445.AM2013-2637