Zfra induction of memory anticancer response via a novel immune cell

ABSTRACT

When naive mice receive short Zfra peptides via tail vein injections, they develop lifetime resistance to growth of many cancer xenografts, due to activation of a novel spleen memory Hyal-2⁺ CD3^– CD19⁻ Z lymphocyte. In vitro education of spleen cells with Zfra activates Z cell for conferring memory anticancer response in vivo.

Introduction

Zinc finger-like protein that regulates apoptosis (Zfra) is a naturally occurring 31-amino-acid protein with several reactive amino acid residues such as Ser8, Cys9, and Cys12.^1-4 Zfra participates in the tumor necrosis factor (TNF)-mediated apoptosis.^1-4 Zfra affects TNF signaling via interacting with TNF receptor adaptor proteins such as TRADD, FADD, and RIP.^1-4 In addition, Zfra negatively controls the function of nuclear factor NF-κB, cJun N-terminal kinase 1 (JNK1), and tumor suppressors p53 and WW domain-containing oxidoreductase (WWOX, FOR, or WOX1).^1,2,5 Zfra is upregulated under stress conditions, whereas its functional role is largely unknown.

Zfra activates spleen Hyal-2⁺ CD3⁻ CD19⁻ lymphocyte for memory anticancer response

T cell-deficient nude mice and immune competent BALB/c mice rapidly develop resistance to the growth of at least 10 types of cancer xenografts when they receive an aliquot of full-length Zfra1-31 peptide once a week for 3 weeks via tail vein injections. It is still effective in cancer prevention even as Zfra4-10, containing just seven amino acids (RRSSSCK).⁶ Zfra blocks cancer metastasis, cancer stem cell development, and spontaneous cancer formation.⁶ Zfra undergoes self-polymerization in a covalent manner under enzyme-free conditons.⁶ Alteration of the Ser8 phosphorylation site abolishes Zfra polymerization and in turn its anticancer function.

Synthetic Zfra in circulation becomes polymerized and is mainly trapped in the spleen.⁶ Zfra binds a novel non-T/non-B spleen lymphocyte, designated Hyal-2⁺ CD3⁻ CD19⁻, or Z (for Zfra binding). Hyaluronidase Hyal-2 is a receptor for Zfra.⁶ We postulate that Zfra activates Z cell via the Hyal-2/WWOX/Smad pathway.^7,8 Healthy BALB/c mice have 25–29% of Z cell in the spleen, whereas tumor-growing mice have only less than 3.3%. These findings are further confirmed by gene chip array analysis (unpublished). Autologous Z cell can be activated in vitro by Zfra peptides, followed by transferring to tumor growing mice for cancer suppression, suggesting that cancer patients can be treated with autologous activated Z cell.

In principle, “immunization” of immune competent and deficient mice with Zfra peptides drives the activation of spleen Z cell, with no adjuvant needed (Fig. 1).⁶ Despite immunodeficiency, Z cell in nude and NOD-SCID mice can be primed for activation by Zfra to fight against cancer. Activated Z cell recognize many cancer cell types, suggesting that polymerized Zfra exhibits cancer-like antigens so that activated Z cell can recognize and destruct cancer cells. Zfra is not toxic and does not cause damages to organs, suggesting its therapeutic potential.⁶

Figure 1.

A schematic illustration for Zfra action and Z cell activation in cancer prevention and treatment. Immunization of immune competent and deficient mice with full-length Zfra1-31 or Zfra4-10 peptide drives the activation of Hyal-2⁺ CD3⁻ CD19⁻ Z cell and thereby blocks cancer growth. Nonetheless, Z cell disappears from the spleen if there is an ongoing tumor growth in the mice. When isolated spleen cells are treated with Zfra in vitro, Z cell becomes activated for conferring memory anticancer response in vivo.

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Funding

This research was supported, in part, by the Department of Defense USA (DAMD17–03-1–0736 and W81XWH-08–1-0682), the National Health Research Institute, Taiwan, ROC (NHRI-EX99–9704BI), and the Department of Health, Taiwan, ROC (DOH101-TD-PB-111-TM010) (to NS Chang). Wan-Pei Su was a recipient of the Graduate/Postdoctoral Travel Award from the American Society for Biochemistry and Molecular Biology (ASBMB) in April 2012.