Limits...
Resistance to oncolytic myxoma virus therapy in nf1(-/-)/trp53(-/-) syngeneic mouse glioma models is independent of anti-viral type-I interferon.

Zemp FJ, McKenzie BA, Lun X, Maxwell L, Reilly KM, McFadden G, Yong VW, Forsyth PA - PLoS ONE (2013)

Bottom Line: Intracranial injection of MYXV failed to result in sustained viral replication or treatment efficacy, with minimal tumour infection that was completely resolved by 7 days post-infection.We hypothesized that the stromal production of Type-I interferons (IFNα/β) could explain the resistance seen in these models; however, we found that neither the cell lines in vitro nor the tumours in vivo produce any IFNα/β in response to MYXV infection.To confirm IFNα/β did not play a role in this resistance, we ablated the ability of tumours to respond to IFNα/β via IRF9 knockdown, and generated identical results.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, Clark H. Smith Brain Tumor Center, University of Calgary, Tom Baker Cancer Centre, Southern Alberta Cancer Research Institute, Calgary, Alberta, Canada.

ABSTRACT
Despite promising preclinical studies, oncolytic viral therapy for malignant gliomas has resulted in variable, but underwhelming results in clinical evaluations. Of concern are the low levels of tumour infection and viral replication within the tumour. This discrepancy between the laboratory and the clinic could result from the disparity of xenograft versus syngeneic models in determining in vivo viral infection, replication and treatment efficacy. Here we describe a panel of primary mouse glioma lines derived from Nf1 (+/-) Trp53 (+/-) mice in the C57Bl/6J background for use in the preclinical testing of the oncolytic virus Myxoma (MYXV). These lines show a range of susceptibility to MYXV replication in vitro, but all succumb to viral-mediated cell death. Two of these lines orthotopically grafted produced aggressive gliomas. Intracranial injection of MYXV failed to result in sustained viral replication or treatment efficacy, with minimal tumour infection that was completely resolved by 7 days post-infection. We hypothesized that the stromal production of Type-I interferons (IFNα/β) could explain the resistance seen in these models; however, we found that neither the cell lines in vitro nor the tumours in vivo produce any IFNα/β in response to MYXV infection. To confirm IFNα/β did not play a role in this resistance, we ablated the ability of tumours to respond to IFNα/β via IRF9 knockdown, and generated identical results. Our studies demonstrate that these syngeneic cell lines are relevant preclinical models for testing experimental glioma treatments, and show that IFNα/β is not responsible for the MYXV treatment resistance seen in syngeneic glioma models.

Show MeSH

Related in: MedlinePlus

K1492 IRF9 knockdown in vivo results in no change in efficacy or viral replication.A – Immunohistochemical confirmation of IRF9 knockdown in K1492 tumours 14 days post-implantation (200×). B – Survival of 5×104 cells of K1492 IRF9 knockdown (IRF9kd) or Scrambled control (Scram) in C57Bl/6J mice receiving 5×106 PFUs vMyx-FLuc (MYXV) or no treatment (NT) on day 14. C – Luciferase measured (Total FLUX) from region-of-interest around the entire mouse skull following 5×106 PFUs vMyx-FLuc in K1492 control (WT), scrambled control (Scram) or IRF9 knockdown (IRF9kd) on day 14. n = 5 for each group and error bars represent standard error.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3675064&req=5

pone-0065801-g006: K1492 IRF9 knockdown in vivo results in no change in efficacy or viral replication.A – Immunohistochemical confirmation of IRF9 knockdown in K1492 tumours 14 days post-implantation (200×). B – Survival of 5×104 cells of K1492 IRF9 knockdown (IRF9kd) or Scrambled control (Scram) in C57Bl/6J mice receiving 5×106 PFUs vMyx-FLuc (MYXV) or no treatment (NT) on day 14. C – Luciferase measured (Total FLUX) from region-of-interest around the entire mouse skull following 5×106 PFUs vMyx-FLuc in K1492 control (WT), scrambled control (Scram) or IRF9 knockdown (IRF9kd) on day 14. n = 5 for each group and error bars represent standard error.

Mentions: To determine if ablating IFN signalling in vivo would overcome resistance to MYXV in vivo, we implanted the K1492 IRF9 knockdown or its scrambled control into C57Bl/6J mice. Importantly, we found that the knockdown persisted in vivo through immunohistochemistry for IRF9 (Figure 6A, S4), and that the knockdown had similar tumour growth kinetics to the K1492 scrambled control. Treatment with vMyx-FLuc resulted in no change in survival (35 days for no treatment versus 30 days for MYXV treatment in Scram-K1492 (Log-rank Mantel-Cox test; p = 0.8279) and 35 days for no treatment versus 36 days for MYXV treatment in IRF9kd-K1492 (Log-rank Mantel-Cox test; p = 0.6406); Figure 6B), with no change in viral luciferase (Figure 6C). These experiments, coupled to the observations of no significant IFNα/β production in vitro and in vivo, strongly suggest that the in vivo resistance to MYXV therapy in the intracranial environment of immunocompetent mice is independent of the quintessential anti-viral IFNα/β signalling.


Resistance to oncolytic myxoma virus therapy in nf1(-/-)/trp53(-/-) syngeneic mouse glioma models is independent of anti-viral type-I interferon.

Zemp FJ, McKenzie BA, Lun X, Maxwell L, Reilly KM, McFadden G, Yong VW, Forsyth PA - PLoS ONE (2013)

K1492 IRF9 knockdown in vivo results in no change in efficacy or viral replication.A – Immunohistochemical confirmation of IRF9 knockdown in K1492 tumours 14 days post-implantation (200×). B – Survival of 5×104 cells of K1492 IRF9 knockdown (IRF9kd) or Scrambled control (Scram) in C57Bl/6J mice receiving 5×106 PFUs vMyx-FLuc (MYXV) or no treatment (NT) on day 14. C – Luciferase measured (Total FLUX) from region-of-interest around the entire mouse skull following 5×106 PFUs vMyx-FLuc in K1492 control (WT), scrambled control (Scram) or IRF9 knockdown (IRF9kd) on day 14. n = 5 for each group and error bars represent standard error.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3675064&req=5

pone-0065801-g006: K1492 IRF9 knockdown in vivo results in no change in efficacy or viral replication.A – Immunohistochemical confirmation of IRF9 knockdown in K1492 tumours 14 days post-implantation (200×). B – Survival of 5×104 cells of K1492 IRF9 knockdown (IRF9kd) or Scrambled control (Scram) in C57Bl/6J mice receiving 5×106 PFUs vMyx-FLuc (MYXV) or no treatment (NT) on day 14. C – Luciferase measured (Total FLUX) from region-of-interest around the entire mouse skull following 5×106 PFUs vMyx-FLuc in K1492 control (WT), scrambled control (Scram) or IRF9 knockdown (IRF9kd) on day 14. n = 5 for each group and error bars represent standard error.
Mentions: To determine if ablating IFN signalling in vivo would overcome resistance to MYXV in vivo, we implanted the K1492 IRF9 knockdown or its scrambled control into C57Bl/6J mice. Importantly, we found that the knockdown persisted in vivo through immunohistochemistry for IRF9 (Figure 6A, S4), and that the knockdown had similar tumour growth kinetics to the K1492 scrambled control. Treatment with vMyx-FLuc resulted in no change in survival (35 days for no treatment versus 30 days for MYXV treatment in Scram-K1492 (Log-rank Mantel-Cox test; p = 0.8279) and 35 days for no treatment versus 36 days for MYXV treatment in IRF9kd-K1492 (Log-rank Mantel-Cox test; p = 0.6406); Figure 6B), with no change in viral luciferase (Figure 6C). These experiments, coupled to the observations of no significant IFNα/β production in vitro and in vivo, strongly suggest that the in vivo resistance to MYXV therapy in the intracranial environment of immunocompetent mice is independent of the quintessential anti-viral IFNα/β signalling.

Bottom Line: Intracranial injection of MYXV failed to result in sustained viral replication or treatment efficacy, with minimal tumour infection that was completely resolved by 7 days post-infection.We hypothesized that the stromal production of Type-I interferons (IFNα/β) could explain the resistance seen in these models; however, we found that neither the cell lines in vitro nor the tumours in vivo produce any IFNα/β in response to MYXV infection.To confirm IFNα/β did not play a role in this resistance, we ablated the ability of tumours to respond to IFNα/β via IRF9 knockdown, and generated identical results.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, Clark H. Smith Brain Tumor Center, University of Calgary, Tom Baker Cancer Centre, Southern Alberta Cancer Research Institute, Calgary, Alberta, Canada.

ABSTRACT
Despite promising preclinical studies, oncolytic viral therapy for malignant gliomas has resulted in variable, but underwhelming results in clinical evaluations. Of concern are the low levels of tumour infection and viral replication within the tumour. This discrepancy between the laboratory and the clinic could result from the disparity of xenograft versus syngeneic models in determining in vivo viral infection, replication and treatment efficacy. Here we describe a panel of primary mouse glioma lines derived from Nf1 (+/-) Trp53 (+/-) mice in the C57Bl/6J background for use in the preclinical testing of the oncolytic virus Myxoma (MYXV). These lines show a range of susceptibility to MYXV replication in vitro, but all succumb to viral-mediated cell death. Two of these lines orthotopically grafted produced aggressive gliomas. Intracranial injection of MYXV failed to result in sustained viral replication or treatment efficacy, with minimal tumour infection that was completely resolved by 7 days post-infection. We hypothesized that the stromal production of Type-I interferons (IFNα/β) could explain the resistance seen in these models; however, we found that neither the cell lines in vitro nor the tumours in vivo produce any IFNα/β in response to MYXV infection. To confirm IFNα/β did not play a role in this resistance, we ablated the ability of tumours to respond to IFNα/β via IRF9 knockdown, and generated identical results. Our studies demonstrate that these syngeneic cell lines are relevant preclinical models for testing experimental glioma treatments, and show that IFNα/β is not responsible for the MYXV treatment resistance seen in syngeneic glioma models.

Show MeSH
Related in: MedlinePlus