Intratumoral gene delivery of anti-cathepsin L single-chain variable fragment by lentiviral vector inhibits tumor progression induced by human melanoma cells

Abstract

We previously demonstrated that the switch from non-to highly tumorigenic phenotype of human melanoma cells is directly related to procathepsin L secretion, which increased cell resistance to complement-mediated cell lysis. Involvement of procathepsin L secretion in tumor growth was clearly demonstrated by three different strategies: (1) inhibition of secreted procathepsin L activity; (2) increase of procathepsin L secretion; and (3) inhibition of procathepsin L secretion. This latter strategy was triggered by intracellular expression of anti-human cathepsin L single-chain variable fragment (ScFv). These previous experiments were performed by processing melanoma cells before their injection into nude mice. We herein designed a new lentiviral vector in which this anti-cathepsin L ScFv was cloned. This lentiviral vector was optimized to allow the highest intracellular expression of anticathepsin L ScFv in transduced melanoma cells. In these transduced cells, procathepsin L secretion was strongly inhibited. In addition, injection of this anti-cathepsin L ScFv lentiviral vector into tumors already induced in nude mice inhibited tumor growth and associated angiogenesis. This is the first report to demonstrate that targeting procathepsin L secretion with anti-cathepsin L ScFv lentiviral construct constitutes a new gene therapy in the challenge to inhibit the growth of tumors induced by human melanoma cells.

Cathepsin L in Normal and Pathological Bone Remodeling

“…In this scenario, Keerthivasan et al [145] have recently shown that, at least in U87MG glioblastoma cells, vascular endothelial growth factor (VEGF) may up-regulate, at the transcriptional level, Cathepsin L. In line with these observations, Chang et al [148] have reported that, in human breast cancer cells, VEGF-A may promote angiogenesis by perturbing the cathepsin-cysteine protease inhibitor balance in venules, thus causing basement membrane degradation. Evident proof of the importance of cross-talk between Cathepsin L and VEGF in promoting tumor angiogenesis in different tumors is provided, in part, by some in vitro studies, which show that the inhibition of human procathepsin L secretion by anti-cathepsin L monoclonal antibodies results in an inhibition of tumor-induced angiogenesis in highly metastatic human melanoma cells [149,150]. In this context, Rebbaa et al [151] have recently shown that Napsul-IIe-Trp-CHO, a specific inhibitor of Cathepsin L, inhibits in vitro VEGF secretion by endothelial cells and Cathepsin L-mediated degradation of the extracellular matrix, while, in vivo, this molecule was able to inhibit tumor growth in nude mice transplanted with neuroblastoma.…”

“…Most of the Cathepsin L-targeted agents developed so far are a series of different classes of antagonist, including active site-directed low-molecular weight inhibitors many of which are endowed with a preferential selectivity for Cathepsin L [79,106,120,[153][154][155][156][157][158]. Endogenous inhibitors [159] or alternative forms of these molecules [160,161], antibodies [149,150], antisense oligonucleotides [126,139,162,163], specific ribozymes targeting Cathepsin L [90,163] or natural products [60,61] have also been proposed as potential therapeutic agents in the treatment of these diseases. Preclinical studies show that some of these molecules are effective, in vitro, in inhibiting the digestion of bone matrix proteins [60,61,67,71,79,106] at the level of resorption lacuna and in promoting bone mineralization; in vivo, these agents have been shown to suppress RANKL or M-CSF or TNF-a stimulated bone pit formation [13,67,79,120].…”

Proteases in cutaneous malignant melanoma: relevance as biomarker and therapeutic target

“…In hypoxic regions, activities of uPA, catB, MMP-2, MT1-MMP, MMP-9 and MMP-7 in tumor cells have been shown to be increased [139][140][141]. Immune cells, on the contrary, show a decreased activity of MMP-9 and MT1-MMP in hypoxic regions [142].…”

Truncated Human Cathepsin L, Encoded by a Novel Splice Variant, Exhibits Altered Subcellular Localization and Cytotoxicity

“…Blockage of this secretion abolishes the tumorigenicty and metastatic potential of human melanoma cells in nude mice [12,13]. Cathepsin L in cytosol is supposed to regulate apoptosis by activation of tBid [14].…”

“…Human cathepsin L is encoded by at least five different mRNA species namely hCATL A, AI, AII, AIII and hCATL B (12)(13)(14)(15). All these hCATL mRNA species are transcribed from the same gene located on chromosome 9q 21-22 [8].…”