Parvovirus H‐1 infection of human glioma cells leads to complete viral replication and efficient cell killing

Abstract

The extremely poor prognosis of malignant gliomas requires the investigation of other than standard therapies, i.e., the application of oncolytic viruses. In our study, we evaluated the effects of the oncosuppressive parvovirus H-1 on different established glioblastoma cell lines of rat and human origin and on short-term/low-passage cultures of human glioblastoma cells. We observed an efficient and dose-dependent killing of all glioma cell cultures at low multiplicities of infectious particles ( Key words: parvovirus H-1; oncolytic virus; human glioma; glioma therapyMalignant primary brain tumors represent a major therapeutic challenge. A median survival time of approximately 12 months gives patients diagnosed with glioblastoma multiforme an extremely grim prognosis. 1 Despite the use of advanced diagnostic and surgical tools (magnetic resonance imaging [MRI], neuronavigation-guided resection), as well as radiation therapy and chemotherapy, no significant improvements have been achieved during the last 20 years. 1 The limited efficacy of current standard therapies requires the investigation of other modes of treatment.Virus-based therapy of malignant gliomas represents, among others, a new concept that includes a broad variety of therapeutic approaches. In general, viruses are used in 2 ways: they are either genetically engineered to serve as vector systems for the transduction of therapeutic genes into the tumors or they are primarily applied as oncolytic agents. Replication-competent oncolytic viruses that possess the property of cytotoxic multiplication in malignant gliomas include adenovirus, 2 herpes simplex virus, 3-6 vesicular stomatitis virus, 7 poliovirus 8 and reovirus. 9 Because adenoviruses, polioviruses and herpes simplex virus are known to damage untransformed cerebral cells and/or induce inflammatory reactions, modified herpes 4,10 -12 and polioviruses 13 devoid of detrimental effects on healthy brain tissue were engineered. Wildtype reovirus is able to induce strong oncolytic effects in malignant glioma cells but not in untransformed cerebral cells. 14 In our study, we investigated another wildtype oncolytic virus, parvovirus H-1, which has not been investigated for its potential toxic effect on human glioma cells.Autonomous parvoviruses such as H-1 and minute virus of mice (MVM) 15 are small (20 -25 nm), nonenveloped, nuclear-replicating viruses with a linear single-stranded DNA genome of about 5 kb. 16 The parvoviral cytotoxicity is attributed, at least in part, to the viral regulatory nonstructural protein NS-1. 17,18 There is evidence suggesting that the smaller nonstructural protein NS-2 may modulate NS-1 cytotoxicity. 19 The molecular mechanism(s) by which NS-1 induces its toxic effect remain elusive to date. Furthermore, autonomous parvoviruses were shown to inhibit tumor formation in laboratory animals. 20,21 To date, no correlation has been established between any human disease and serologic evidence of a previous infection with autonomous parvoviruses. 22 In 2 phase-I clinical trials, ...

Retargeting of Rat Parvovirus H-1PV to Cancer Cells through Genetic Engineering of the Viral Capsid

“…Taken together, these properties make these viruses very attractive candidates for use as anticancer agents. This study focuses on rat H-1PV, which infects and kills human tumor cell lines of various origins (e.g., of brain [23], pancreas [4,14], blood [3], colon [38], cervix [20], and breast [66,67]) and which is currently under evaluation in a phase I/IIa clinical trial for the treatment of patients with recurrent glioblastoma multiforme (57). H-1PV has the ability to induce different cell death pathways in cancer cells, including necrosis (53), apoptosis (28,46,54,65), and lysosome-dependent cell death (16), while sparing nontransformed cells.…”

LuIII Parvovirus Selectively and Efficiently Targets, Replicates in, and Kills Human Glioma Cells

“…Although a wide variety of parvovirus genus members have been identified, studies of parvoviral growth in human glioblastomas appear to have been limited to MVM (44,53) and H-1 (1,26). In our hands, the majority of parvoviruses that we tested showed only weak or insubstantial effectiveness in infection and destruc- tion of human glioma; these included MVMi, MVMc, MVM-G17, TVX, CPV, PPV, RPV1A, and H-3.…”

“…Killing of rat glioma RG2 by H-1, a rat parvovirus, was highly efficient. In contrast, H-1 infection of the human glioma line U343MG, and 3 of 4 primary human gliomas, when performed at an MOI 50-fold higher than that for the rat glioma, slowed but did not prevent continued cell proliferation through 6 dpi; only 1 of 4 human gliomas showed a reduction in cell number (26). The continued growth of most human gliomas even with high-MOI H-1 infection suggests inefficient and nonprogressive viral replication.…”

“…The efficacy of H-1 was previously studied in two rat GBM lines, a human glioma line (U343MG), and several short-term cultures of primary human gliomas (15,26). Killing of rat glioma RG2 by H-1, a rat parvovirus, was highly efficient.…”

“…Parvovirus-mediated oncosuppression has been observed in vivo for a number of tumor types (43), including GBM, against which H-1 parvovirus has shown particular promise in rat models (22). Recently, based on this and other promising preclinical studies (15,26,31,43), a clinical phase I trial of H-1 against GBM has been initiated (clinical trials.gov NCT01301430). In addition, we and others (44,53) have previously studied in vitro infection characteristics of murine parvovirus strains MVMi and MVMp.…”