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A dynamical systems model for combinatorial cancer therapy enhances oncolytic adenovirus efficacy by MEK-inhibition.

Bagheri N, Shiina M, Lauffenburger DA, Korn WM - PLoS Comput. Biol. (2011)

Bottom Line: Specifically, we fit a nonlinear differential equation system to dedicated experimental data and analyzed the resulting simulations for favorable treatment strategies.Simulations predicted enhanced combinatorial therapy when both treatments were applied simultaneously; we successfully validated these predictions in an ensuing explicit test study.We conclude that integrated computational and experimental analysis of combinatorial therapy provides a useful means to identify treatment/infection protocols that yield clinically significant oncolysis.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.

ABSTRACT
Oncolytic adenoviruses, such as ONYX-015, have been tested in clinical trials for currently untreatable tumors, but have yet to demonstrate adequate therapeutic efficacy. The extent to which viruses infect targeted cells determines the efficacy of this approach but many tumors down-regulate the Coxsackievirus and Adenovirus Receptor (CAR), rendering them less susceptible to infection. Disrupting MAPK pathway signaling by pharmacological inhibition of MEK up-regulates CAR expression, offering possible enhanced adenovirus infection. MEK inhibition, however, interferes with adenovirus replication due to resulting G1-phase cell cycle arrest. Therefore, enhanced efficacy will depend on treatment protocols that productively balance these competing effects. Predictive understanding of how to attain and enhance therapeutic efficacy of combinatorial treatment is difficult since the effects of MEK inhibitors, in conjunction with adenovirus/cell interactions, are complex nonlinear dynamic processes. We investigated combinatorial treatment strategies using a mathematical model that predicts the impact of MEK inhibition on tumor cell proliferation, ONYX-015 infection, and oncolysis. Specifically, we fit a nonlinear differential equation system to dedicated experimental data and analyzed the resulting simulations for favorable treatment strategies. Simulations predicted enhanced combinatorial therapy when both treatments were applied simultaneously; we successfully validated these predictions in an ensuing explicit test study. Further analysis revealed that a CAR-independent mechanism may be responsible for amplified virus production and cell death. We conclude that integrated computational and experimental analysis of combinatorial therapy provides a useful means to identify treatment/infection protocols that yield clinically significant oncolysis. Enhanced oncolytic therapy has the potential to dramatically improve non-surgical cancer treatment, especially in locally advanced or metastatic cases where treatment options remain limited.

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CI1040 up-regulates CAR, induces G1 cell cycle arrest, and sensitizes cells to infection.HCT116 cells were treated with MEK inhibitor CI1040, DMSO, or alone. (A) Treatment was continuous for 4 days. CAR expression was measured 1–4 days post-treatment initiation by FACS; error bars represent standard deviation of triplicate measurements. (B) Cells were treated with CI1040 for 1 day, 2 days, or 3 days, and harvested 1–7 days following initial treatment. Cell density was determined (red and black data markers); error bars represent standard deviation of triplicate measurements. Each time course was replicated. Solid blue lines correspond to simulated proliferation dynamics with respective CI1040 treatment. (C) Cell cycle phase was measured 1–3 days post treatment with CI1040 or DMSO through PI staining. (D–E) Cells were treated with CI1040 or DMSO for 2 days, treatment is removed by media change, and cells were immediately infected with ONYX-015/GFP (D) or ONYX-015 (E) at MOIs 0.1, 1, 2 (not shown), 5, and 10. GFP expression (determined by FACS analysis) and cell viability was measured 1–6 days post-infection. (F) Cells were treated with CI1040 for 2 days, treatment was removed by media change, and cells were immediately infected with ONYX-015 at MOIs of 0.1 and 1. Virus replication was observed 1–10 days post infection.
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pcbi-1001085-g001: CI1040 up-regulates CAR, induces G1 cell cycle arrest, and sensitizes cells to infection.HCT116 cells were treated with MEK inhibitor CI1040, DMSO, or alone. (A) Treatment was continuous for 4 days. CAR expression was measured 1–4 days post-treatment initiation by FACS; error bars represent standard deviation of triplicate measurements. (B) Cells were treated with CI1040 for 1 day, 2 days, or 3 days, and harvested 1–7 days following initial treatment. Cell density was determined (red and black data markers); error bars represent standard deviation of triplicate measurements. Each time course was replicated. Solid blue lines correspond to simulated proliferation dynamics with respective CI1040 treatment. (C) Cell cycle phase was measured 1–3 days post treatment with CI1040 or DMSO through PI staining. (D–E) Cells were treated with CI1040 or DMSO for 2 days, treatment is removed by media change, and cells were immediately infected with ONYX-015/GFP (D) or ONYX-015 (E) at MOIs 0.1, 1, 2 (not shown), 5, and 10. GFP expression (determined by FACS analysis) and cell viability was measured 1–6 days post-infection. (F) Cells were treated with CI1040 for 2 days, treatment was removed by media change, and cells were immediately infected with ONYX-015 at MOIs of 0.1 and 1. Virus replication was observed 1–10 days post infection.

Mentions: In order to generate sufficient experimental data quantifying the mechanistic behavior critical to predicting nonlinear dynamics, we systematically assessed CAR expression, cell proliferation, infection, cell viability, and viral replication in the presence and absence of MEK inhibitors (namely, CI1040). In agreement with our previously published work [16], we found that disrupting the MAPK signaling pathway through pharmacological inhibition of MEK nearly doubles the number of CAR molecules per cell relative to the control (DMSO-treated) cells. The largest increase in receptor levels occurred 2 days after CI1040 treatment initiation (Figure 1a). Such restoration also presented a tradeoff: MEK-inhibition caused G1-phase cell cycle arrest (Figure 1b and 1c). Previous studies indicated that cell cycle arrest inhibits production of new virus particles and virus replication [17]. We therefore hypothesized that effective oncolytic adenovirus infection requires pre-treatment of cells with MEK inhibitor for a sufficient amount of time, providing increased receptor expression at the cell surface. To allow the cell cycle to proceed, treatment should be followed by removal of the inhibitor at the time of infection. Thus, we pre-treated cells with either CI1040 or DMSO for 2 days prior to infecting cells at multiplicities of infection (MOIs) of 0.1, 1, 2, 5, and 10. We observed increased infection (Figure 1d) and found that viability of HCT116 cells pre-treated with CI1040 decreased by 60% or 65% six days post infection following MOIs of 0.1 and 1 (respectively) when compared to the DMSO control (Figure 1e). At higher MOI, pre-treatment with MEK-inhibitor accelerated cell killing by as much as 3 days. In agreement with the observed enhanced cell death upon CI1040 pre-treatment, virus production also improved: virus titer increased 20-fold at MOI of 0.1 and 5-fold at MOI of 1 when measured five days post-infection (Figure 1f). Our findings suggest that treating cells with MEK-inhibitor prior to infection increases CAR expression, arrests cells in G1 cell cycle phase, and sensitizes cells to infection such that we observe reduced viability and improved virus replication.


A dynamical systems model for combinatorial cancer therapy enhances oncolytic adenovirus efficacy by MEK-inhibition.

Bagheri N, Shiina M, Lauffenburger DA, Korn WM - PLoS Comput. Biol. (2011)

CI1040 up-regulates CAR, induces G1 cell cycle arrest, and sensitizes cells to infection.HCT116 cells were treated with MEK inhibitor CI1040, DMSO, or alone. (A) Treatment was continuous for 4 days. CAR expression was measured 1–4 days post-treatment initiation by FACS; error bars represent standard deviation of triplicate measurements. (B) Cells were treated with CI1040 for 1 day, 2 days, or 3 days, and harvested 1–7 days following initial treatment. Cell density was determined (red and black data markers); error bars represent standard deviation of triplicate measurements. Each time course was replicated. Solid blue lines correspond to simulated proliferation dynamics with respective CI1040 treatment. (C) Cell cycle phase was measured 1–3 days post treatment with CI1040 or DMSO through PI staining. (D–E) Cells were treated with CI1040 or DMSO for 2 days, treatment is removed by media change, and cells were immediately infected with ONYX-015/GFP (D) or ONYX-015 (E) at MOIs 0.1, 1, 2 (not shown), 5, and 10. GFP expression (determined by FACS analysis) and cell viability was measured 1–6 days post-infection. (F) Cells were treated with CI1040 for 2 days, treatment was removed by media change, and cells were immediately infected with ONYX-015 at MOIs of 0.1 and 1. Virus replication was observed 1–10 days post infection.
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pcbi-1001085-g001: CI1040 up-regulates CAR, induces G1 cell cycle arrest, and sensitizes cells to infection.HCT116 cells were treated with MEK inhibitor CI1040, DMSO, or alone. (A) Treatment was continuous for 4 days. CAR expression was measured 1–4 days post-treatment initiation by FACS; error bars represent standard deviation of triplicate measurements. (B) Cells were treated with CI1040 for 1 day, 2 days, or 3 days, and harvested 1–7 days following initial treatment. Cell density was determined (red and black data markers); error bars represent standard deviation of triplicate measurements. Each time course was replicated. Solid blue lines correspond to simulated proliferation dynamics with respective CI1040 treatment. (C) Cell cycle phase was measured 1–3 days post treatment with CI1040 or DMSO through PI staining. (D–E) Cells were treated with CI1040 or DMSO for 2 days, treatment is removed by media change, and cells were immediately infected with ONYX-015/GFP (D) or ONYX-015 (E) at MOIs 0.1, 1, 2 (not shown), 5, and 10. GFP expression (determined by FACS analysis) and cell viability was measured 1–6 days post-infection. (F) Cells were treated with CI1040 for 2 days, treatment was removed by media change, and cells were immediately infected with ONYX-015 at MOIs of 0.1 and 1. Virus replication was observed 1–10 days post infection.
Mentions: In order to generate sufficient experimental data quantifying the mechanistic behavior critical to predicting nonlinear dynamics, we systematically assessed CAR expression, cell proliferation, infection, cell viability, and viral replication in the presence and absence of MEK inhibitors (namely, CI1040). In agreement with our previously published work [16], we found that disrupting the MAPK signaling pathway through pharmacological inhibition of MEK nearly doubles the number of CAR molecules per cell relative to the control (DMSO-treated) cells. The largest increase in receptor levels occurred 2 days after CI1040 treatment initiation (Figure 1a). Such restoration also presented a tradeoff: MEK-inhibition caused G1-phase cell cycle arrest (Figure 1b and 1c). Previous studies indicated that cell cycle arrest inhibits production of new virus particles and virus replication [17]. We therefore hypothesized that effective oncolytic adenovirus infection requires pre-treatment of cells with MEK inhibitor for a sufficient amount of time, providing increased receptor expression at the cell surface. To allow the cell cycle to proceed, treatment should be followed by removal of the inhibitor at the time of infection. Thus, we pre-treated cells with either CI1040 or DMSO for 2 days prior to infecting cells at multiplicities of infection (MOIs) of 0.1, 1, 2, 5, and 10. We observed increased infection (Figure 1d) and found that viability of HCT116 cells pre-treated with CI1040 decreased by 60% or 65% six days post infection following MOIs of 0.1 and 1 (respectively) when compared to the DMSO control (Figure 1e). At higher MOI, pre-treatment with MEK-inhibitor accelerated cell killing by as much as 3 days. In agreement with the observed enhanced cell death upon CI1040 pre-treatment, virus production also improved: virus titer increased 20-fold at MOI of 0.1 and 5-fold at MOI of 1 when measured five days post-infection (Figure 1f). Our findings suggest that treating cells with MEK-inhibitor prior to infection increases CAR expression, arrests cells in G1 cell cycle phase, and sensitizes cells to infection such that we observe reduced viability and improved virus replication.

Bottom Line: Specifically, we fit a nonlinear differential equation system to dedicated experimental data and analyzed the resulting simulations for favorable treatment strategies.Simulations predicted enhanced combinatorial therapy when both treatments were applied simultaneously; we successfully validated these predictions in an ensuing explicit test study.We conclude that integrated computational and experimental analysis of combinatorial therapy provides a useful means to identify treatment/infection protocols that yield clinically significant oncolysis.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.

ABSTRACT
Oncolytic adenoviruses, such as ONYX-015, have been tested in clinical trials for currently untreatable tumors, but have yet to demonstrate adequate therapeutic efficacy. The extent to which viruses infect targeted cells determines the efficacy of this approach but many tumors down-regulate the Coxsackievirus and Adenovirus Receptor (CAR), rendering them less susceptible to infection. Disrupting MAPK pathway signaling by pharmacological inhibition of MEK up-regulates CAR expression, offering possible enhanced adenovirus infection. MEK inhibition, however, interferes with adenovirus replication due to resulting G1-phase cell cycle arrest. Therefore, enhanced efficacy will depend on treatment protocols that productively balance these competing effects. Predictive understanding of how to attain and enhance therapeutic efficacy of combinatorial treatment is difficult since the effects of MEK inhibitors, in conjunction with adenovirus/cell interactions, are complex nonlinear dynamic processes. We investigated combinatorial treatment strategies using a mathematical model that predicts the impact of MEK inhibition on tumor cell proliferation, ONYX-015 infection, and oncolysis. Specifically, we fit a nonlinear differential equation system to dedicated experimental data and analyzed the resulting simulations for favorable treatment strategies. Simulations predicted enhanced combinatorial therapy when both treatments were applied simultaneously; we successfully validated these predictions in an ensuing explicit test study. Further analysis revealed that a CAR-independent mechanism may be responsible for amplified virus production and cell death. We conclude that integrated computational and experimental analysis of combinatorial therapy provides a useful means to identify treatment/infection protocols that yield clinically significant oncolysis. Enhanced oncolytic therapy has the potential to dramatically improve non-surgical cancer treatment, especially in locally advanced or metastatic cases where treatment options remain limited.

Show MeSH
Related in: MedlinePlus