IL-4 receptors on human medulloblastoma tumours serve as a sensitive target for a circular permuted IL-4-Pseudomonas exotoxin fusion protein

Abstract

Cytotoxins directed to interleukin-4 receptors have shown to mediate relatively selective cytotoxicity against a variety of human cancer cells in vitro and in vivo. In an ongoing Phase I clinical trial, a recombinant protein comprised of circularly permuted IL-4 fused to a mutated form of Pseudomonas exotoxin (the fusion protein termed IL-4(38-37)-PE38KDEL or cpIL4-PE) has shown antitumour activity against malignant glioma. Human medulloblastomas are neuroectodermal tumours that occur in children and have a poor prognosis. The goal of this study was to determine whether human medulloblastoma derived cell lines express interleukin-4 receptor and whether interleukin-4 receptor expression is accompanied by sensitivity to cpIL4-PE. Medulloblastoma cell lines express interleukin-4 receptor at the protein and mRNA levels as determined by binding, indirect immunofluorescence and RT -PCR studies. These cells expressed IL-4Ra (also known as IL-4Rb) and IL-13Ra1 (also known as IL-13Ra') chains, however common g c , a component of the interleukin-4 receptor system in immune cells was not detected. Consistent with the expression of IL-4R, cpIL4-PE was found to be highly and specifically cytotoxic to four of five medulloblastoma cell lines. Susceptibility of medulloblastoma cell lines to cpIL4-PE seemed to correlate closely to the functional IL-4 binding sites in general as demonstrated by 125 I-IL-4 binding, but did not seem to correlate with mRNA or cell surface immunoreactive receptor protein expression. The sensitivity of medulloblastoma cells to cpIL4-PE could be eliminated by concurrent incubation with IL-4 or IL-13, but not with IL-2. None of these cell lines showed any change in proliferation upon treatment with exogenous IL-4. These studies establish the interleukin-4 receptor as a medulloblastoma-associated target for possible tumour-directed cancer therapy. Further studies are warranted to investigate interleukin-4 receptor expression in primary medulloblastoma tumours and sensitivity to cpIL-4PE in vitro and in vivo.

Pseudomonas exotoxin A: From virulence factor to anti-cancer agent

“…It caused tumor regressions in mice bearing human breast, head, and neck squamous cell (SSCHN) or pancreatic tumors Kawakami et al, 2002;Strome et al, 2002). It also showed specific cytotoxicity against head and neck cancer and medulloblastoma cells (Kawakami et al, 2000;Joshi et al, 2002). Kawakami et al (2001) also tested the anti-IL13-R immunotoxin IL13-PE38QQR, which showed remarkable tumor responses with complete remissions after intratumoral administration in head and neck tumors, which were implanted subcutaneously in nude mice.…”

Expression and structure of interleukin 4 receptors in primary meningeal tumors

“…These results are similar to what was reported previously in gliomas. [17][18][19] The expression of IL-4R within the tumors points to intratumor heterogeneity within meningiomas and may define a unique population of cells that is not detectable otherwise by conventional hematoxylin and eosin staining.…”

“…[12][13][14] Different histopathologic grades of primary glial tumors that account for 40% of all central nervous system neoplasms also express large numbers of IL-4 receptors. [17][18][19] However, to date, there has been no study on the patterns of expression of IL-4R in meningiomas.…”

“…18 Brain tumor cells, including glioblastoma, astrocytoma, and medulloblastoma, overexpress IL-4R and IL-13R. 19 They also express other growth factor receptors, e.g., high-affinity forms of fibroblast growth factor receptor 1-␤, 26 epidermal growth factor receptor, 27,28 insulinlike growth receptor, 29 -31 , transferring receptor (TfR), 32 urokinase receptor, 33 and IL-13 receptors. 34 -42 In addition, many studies have reported the expression of vascular endothelial growth factor receptors, erythropoietin receptor, [43][44][45][46][47][48] and platelet-derived growth factor receptors in brain malignancies.…”

Molecular Markers of Glial Tumors: Current Targeting Strategies

“…This form is expressed in immune cells and hematologic malignancies [31] and signals through the Jak1 and Jak3 tyrosine kinases [32]. Type II (alternative) IL-4Rs are comprised of an IL-4Rα chain and an IL-13Rα1 subunit [33] and are expressed in solid tumors, including glioblastomas. Signaling is through Jak1 and Jak2 tyrosine kinases [32].…”