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Multi-modality therapeutics with potent anti-tumor effects: photochemical internalization enhances delivery of the fusion toxin scFvMEL/rGel.

Selbo PK, Rosenblum MG, Cheung LH, Zhang W, Berg K - PLoS ONE (2009)

Bottom Line: The recombinant single-chain fusion construct scFvMEL/rGel is composed of an antibody targeting the progenitor marker HMW-MAA/NG2/MGP/gp240 and the highly effective toxin gelonin (rGel).PCI performed by light activation of cells co-incubated with scFvMEL/rGel and the endo-lysosomal targeting photosensitizers AlPcS(2a) or TPPS(2a) resulted in enhanced cytotoxic effects against antigen-positive cell lines, while no differences in cytotoxicity between the scFvMEL/rGel and rGel were observed in antigen-negative cells.The present DDS warrants further evaluation of its clinical potential.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway. selbo@rr-research.no

ABSTRACT

Background: There is a need for drug delivery systems (DDS) that can enhance cytosolic delivery of anti-cancer drugs trapped in the endo-lysosomal compartments. Exposure of cells to specific photosensitizers followed by light exposure (photochemical internalization, PCI) results in transfer of agents from the endocytic compartment into the cytosol.

Methodology and principal findings: The recombinant single-chain fusion construct scFvMEL/rGel is composed of an antibody targeting the progenitor marker HMW-MAA/NG2/MGP/gp240 and the highly effective toxin gelonin (rGel). Here we demonstrate enhanced tumor cell selectivity, cytosolic delivery and anti-tumor activity by applying PCI of scFvMEL/rGel. PCI performed by light activation of cells co-incubated with scFvMEL/rGel and the endo-lysosomal targeting photosensitizers AlPcS(2a) or TPPS(2a) resulted in enhanced cytotoxic effects against antigen-positive cell lines, while no differences in cytotoxicity between the scFvMEL/rGel and rGel were observed in antigen-negative cells. Mice bearing well-developed melanoma (A-375) xenografts (50-100 mm(3)) were treated with PCI of scFvMEL/rGel. By 30 days after injection, approximately 100% of mice in the control groups had tumors>800 mm(3). In contrast, by day 40, 50% of mice in the PCI of scFvMEL/rGel combination group had tumors<800 mm(3) with no increase in tumor size up to 110 days. PCI of scFvMEL/rGel resulted in a synergistic effect (p<0.05) and complete regression (CR) in 33% of tumor-bearing mice (n = 12).

Conclusions/significance: This is a unique demonstration that a non-invasive multi-modality approach combining a recombinant, targeted therapeutic such as scFvMEL/rGel and PCI act in concert to provide potent in vivo efficacy without sacrificing selectivity or enhancing toxicity. The present DDS warrants further evaluation of its clinical potential.

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PCI of scFvMEL/rGel in MA11 breast carcinoma cells (A) and U87 malignant glioma cells (B).The cells were incubated with 5.0 µg/ml AlPcS2a+/−16.5 nM scFvMEL/rGel or 16.5 nM rGel for 18 hours and then washed twice and chased in drug-free medium 4 h prior to red light exposure. MTT assay was performed 48 hours post light. Experiments with triplicates were reproduced at least twice. Bars, SE.
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pone-0006691-g003: PCI of scFvMEL/rGel in MA11 breast carcinoma cells (A) and U87 malignant glioma cells (B).The cells were incubated with 5.0 µg/ml AlPcS2a+/−16.5 nM scFvMEL/rGel or 16.5 nM rGel for 18 hours and then washed twice and chased in drug-free medium 4 h prior to red light exposure. MTT assay was performed 48 hours post light. Experiments with triplicates were reproduced at least twice. Bars, SE.

Mentions: To demonstrate a general applicability of the PCI-based DDS PCI of scFvMEL/rGel were evaluated in two other cell lines of different cancer origins: Lobular breast carcinoma (MA11) and malignant glioblastoma (U87MG) from brain cancer, the latter shown to express NG2 [9]. Expression of the target receptor on MA11 cells was confirmed by detecting receptor-binding of scFvMEL/rGel by using a primary rabbit antibody against gelonin and an Alexa488 labeled secondary goat anti rabbit antibody, while control experiment using incubation of the primary and the secondary antibody alone resulted in no fluorescing signals (Figure S5). PCI in these cell lines resulted in a strongly enhanced light-dose and toxin-dose dependent cytotoxicity compared to either PDT alone or fusion toxin treatment alone (Figure 3). No dark toxicity of PS alone or in combination with the fusion toxin was observed in both cell lines (Figure 3A).


Multi-modality therapeutics with potent anti-tumor effects: photochemical internalization enhances delivery of the fusion toxin scFvMEL/rGel.

Selbo PK, Rosenblum MG, Cheung LH, Zhang W, Berg K - PLoS ONE (2009)

PCI of scFvMEL/rGel in MA11 breast carcinoma cells (A) and U87 malignant glioma cells (B).The cells were incubated with 5.0 µg/ml AlPcS2a+/−16.5 nM scFvMEL/rGel or 16.5 nM rGel for 18 hours and then washed twice and chased in drug-free medium 4 h prior to red light exposure. MTT assay was performed 48 hours post light. Experiments with triplicates were reproduced at least twice. Bars, SE.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2723936&req=5

pone-0006691-g003: PCI of scFvMEL/rGel in MA11 breast carcinoma cells (A) and U87 malignant glioma cells (B).The cells were incubated with 5.0 µg/ml AlPcS2a+/−16.5 nM scFvMEL/rGel or 16.5 nM rGel for 18 hours and then washed twice and chased in drug-free medium 4 h prior to red light exposure. MTT assay was performed 48 hours post light. Experiments with triplicates were reproduced at least twice. Bars, SE.
Mentions: To demonstrate a general applicability of the PCI-based DDS PCI of scFvMEL/rGel were evaluated in two other cell lines of different cancer origins: Lobular breast carcinoma (MA11) and malignant glioblastoma (U87MG) from brain cancer, the latter shown to express NG2 [9]. Expression of the target receptor on MA11 cells was confirmed by detecting receptor-binding of scFvMEL/rGel by using a primary rabbit antibody against gelonin and an Alexa488 labeled secondary goat anti rabbit antibody, while control experiment using incubation of the primary and the secondary antibody alone resulted in no fluorescing signals (Figure S5). PCI in these cell lines resulted in a strongly enhanced light-dose and toxin-dose dependent cytotoxicity compared to either PDT alone or fusion toxin treatment alone (Figure 3). No dark toxicity of PS alone or in combination with the fusion toxin was observed in both cell lines (Figure 3A).

Bottom Line: The recombinant single-chain fusion construct scFvMEL/rGel is composed of an antibody targeting the progenitor marker HMW-MAA/NG2/MGP/gp240 and the highly effective toxin gelonin (rGel).PCI performed by light activation of cells co-incubated with scFvMEL/rGel and the endo-lysosomal targeting photosensitizers AlPcS(2a) or TPPS(2a) resulted in enhanced cytotoxic effects against antigen-positive cell lines, while no differences in cytotoxicity between the scFvMEL/rGel and rGel were observed in antigen-negative cells.The present DDS warrants further evaluation of its clinical potential.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway. selbo@rr-research.no

ABSTRACT

Background: There is a need for drug delivery systems (DDS) that can enhance cytosolic delivery of anti-cancer drugs trapped in the endo-lysosomal compartments. Exposure of cells to specific photosensitizers followed by light exposure (photochemical internalization, PCI) results in transfer of agents from the endocytic compartment into the cytosol.

Methodology and principal findings: The recombinant single-chain fusion construct scFvMEL/rGel is composed of an antibody targeting the progenitor marker HMW-MAA/NG2/MGP/gp240 and the highly effective toxin gelonin (rGel). Here we demonstrate enhanced tumor cell selectivity, cytosolic delivery and anti-tumor activity by applying PCI of scFvMEL/rGel. PCI performed by light activation of cells co-incubated with scFvMEL/rGel and the endo-lysosomal targeting photosensitizers AlPcS(2a) or TPPS(2a) resulted in enhanced cytotoxic effects against antigen-positive cell lines, while no differences in cytotoxicity between the scFvMEL/rGel and rGel were observed in antigen-negative cells. Mice bearing well-developed melanoma (A-375) xenografts (50-100 mm(3)) were treated with PCI of scFvMEL/rGel. By 30 days after injection, approximately 100% of mice in the control groups had tumors>800 mm(3). In contrast, by day 40, 50% of mice in the PCI of scFvMEL/rGel combination group had tumors<800 mm(3) with no increase in tumor size up to 110 days. PCI of scFvMEL/rGel resulted in a synergistic effect (p<0.05) and complete regression (CR) in 33% of tumor-bearing mice (n = 12).

Conclusions/significance: This is a unique demonstration that a non-invasive multi-modality approach combining a recombinant, targeted therapeutic such as scFvMEL/rGel and PCI act in concert to provide potent in vivo efficacy without sacrificing selectivity or enhancing toxicity. The present DDS warrants further evaluation of its clinical potential.

Show MeSH
Related in: MedlinePlus