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Nanoformulation of Geranylgeranyltransferase-I Inhibitors for Cancer Therapy: Liposomal Encapsulation and pH-Dependent Delivery to Cancer Cells.

Lu J, Yoshimura K, Goto K, Lee C, Hamura K, Kwon O, Tamanoi F - PLoS ONE (2015)

Bottom Line: Delivery of GGTI to human pancreatic cancer cells was demonstrated by the inhibition of protein geranylgeranylation inside the cell and this effect was blocked by Bafilomycin A1.Our results show that the activated K-Ras signaling in these cells can be effectively inhibited and that synergistic effect of the two drugs is observed.Our results suggest a new direction in the use of GGTI for cancer therapy.

View Article: PubMed Central - PubMed

Affiliation: Dept. of Microbiology, Immunology and Molecular Genetics, Jonsson Comprehensive Cancer Center, University of California Los Angeles, Los Angeles, CA 90095, United States of America.

ABSTRACT
Small molecule inhibitors against protein geranylgeranyltransferase-I such as P61A6 have been shown to inhibit proliferation of a variety of human cancer cells and exhibit antitumor activity in mouse models. Development of these inhibitors could be dramatically accelerated by conferring tumor targeting and controlled release capability. As a first step towards this goal, we have encapsulated P61A6 into a new type of liposomes that open and release cargos only under low pH condition. These low pH-release type liposomes were prepared by adjusting the ratio of two types of phospholipid derivatives. Loading of geranylgeranyltransferase-I inhibitor (GGTI) generated liposomes with average diameter of 50-100 nm. GGTI release in solution was sharply dependent on pH values, only showing release at pH lower than 6. Release of cargos in a pH-dependent manner inside the cell was demonstrated by the use of a proton pump inhibitor Bafilomycin A1 that Increased lysosomal pH and inhibited the release of a dye carried in the pH-liposome. Delivery of GGTI to human pancreatic cancer cells was demonstrated by the inhibition of protein geranylgeranylation inside the cell and this effect was blocked by Bafilomycin A1. In addition, GGTI delivered by pH-liposomes induced proliferation inhibition, G1 cell cycle arrest that is associated with the expression of cell cycle regulator p21CIP1/WAF1. Proliferation inhibition was also observed with various lung cancer cell lines. Availability of nanoformulated GGTI opens up the possibility to combine with other types of inhibitors. To demonstrate this point, we combined the liposomal-GGTI with farnesyltransferase inhibitor (FTI) to inhibit K-Ras signaling in pancreatic cancer cells. Our results show that the activated K-Ras signaling in these cells can be effectively inhibited and that synergistic effect of the two drugs is observed. Our results suggest a new direction in the use of GGTI for cancer therapy.

No MeSH data available.


Related in: MedlinePlus

Effect of combination of liposomal GGTI and FTI on MiaPaCa-2 cells.A: Effects of GGTI or FTI alone as well as the combination of the two on ERK phosphorylation were examined by Western blot after 12 hours of treatment. Total ERK is used as loading control. B: the same experiment was repeated with liposomal GGTI (Lipo-GGTI) and FTI. C: Effects of the combination of liposomal-GGTI and FTI on proliferation of MiaPaCa-2 cells after the treatment for 48 hours. FTI and liposomal GGTI concentrations are varied.
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pone.0137595.g006: Effect of combination of liposomal GGTI and FTI on MiaPaCa-2 cells.A: Effects of GGTI or FTI alone as well as the combination of the two on ERK phosphorylation were examined by Western blot after 12 hours of treatment. Total ERK is used as loading control. B: the same experiment was repeated with liposomal GGTI (Lipo-GGTI) and FTI. C: Effects of the combination of liposomal-GGTI and FTI on proliferation of MiaPaCa-2 cells after the treatment for 48 hours. FTI and liposomal GGTI concentrations are varied.

Mentions: To explore the possibility of combining liposomal-GGTI with FTI, we treated pancreatic cancer cells MiaPaCa-2 with liposomal-GGTI and FTI for 12 hours and examined its effect on ERK phosphorylation. As shown in Fig 6B, combination of FTI and Liposomal-GGTI led to complete inhibition of ERK phosphorylation in cancer cells, while treatment with either Liposomal-GGTI or FTI alone only partially inhibited ERK phosphorylation. The total amount of ERK was unaffected by these treatments. These results are similar to those obtained using free drug combinations, GGTI and FTI (Fig 6A).


Nanoformulation of Geranylgeranyltransferase-I Inhibitors for Cancer Therapy: Liposomal Encapsulation and pH-Dependent Delivery to Cancer Cells.

Lu J, Yoshimura K, Goto K, Lee C, Hamura K, Kwon O, Tamanoi F - PLoS ONE (2015)

Effect of combination of liposomal GGTI and FTI on MiaPaCa-2 cells.A: Effects of GGTI or FTI alone as well as the combination of the two on ERK phosphorylation were examined by Western blot after 12 hours of treatment. Total ERK is used as loading control. B: the same experiment was repeated with liposomal GGTI (Lipo-GGTI) and FTI. C: Effects of the combination of liposomal-GGTI and FTI on proliferation of MiaPaCa-2 cells after the treatment for 48 hours. FTI and liposomal GGTI concentrations are varied.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4564137&req=5

pone.0137595.g006: Effect of combination of liposomal GGTI and FTI on MiaPaCa-2 cells.A: Effects of GGTI or FTI alone as well as the combination of the two on ERK phosphorylation were examined by Western blot after 12 hours of treatment. Total ERK is used as loading control. B: the same experiment was repeated with liposomal GGTI (Lipo-GGTI) and FTI. C: Effects of the combination of liposomal-GGTI and FTI on proliferation of MiaPaCa-2 cells after the treatment for 48 hours. FTI and liposomal GGTI concentrations are varied.
Mentions: To explore the possibility of combining liposomal-GGTI with FTI, we treated pancreatic cancer cells MiaPaCa-2 with liposomal-GGTI and FTI for 12 hours and examined its effect on ERK phosphorylation. As shown in Fig 6B, combination of FTI and Liposomal-GGTI led to complete inhibition of ERK phosphorylation in cancer cells, while treatment with either Liposomal-GGTI or FTI alone only partially inhibited ERK phosphorylation. The total amount of ERK was unaffected by these treatments. These results are similar to those obtained using free drug combinations, GGTI and FTI (Fig 6A).

Bottom Line: Delivery of GGTI to human pancreatic cancer cells was demonstrated by the inhibition of protein geranylgeranylation inside the cell and this effect was blocked by Bafilomycin A1.Our results show that the activated K-Ras signaling in these cells can be effectively inhibited and that synergistic effect of the two drugs is observed.Our results suggest a new direction in the use of GGTI for cancer therapy.

View Article: PubMed Central - PubMed

Affiliation: Dept. of Microbiology, Immunology and Molecular Genetics, Jonsson Comprehensive Cancer Center, University of California Los Angeles, Los Angeles, CA 90095, United States of America.

ABSTRACT
Small molecule inhibitors against protein geranylgeranyltransferase-I such as P61A6 have been shown to inhibit proliferation of a variety of human cancer cells and exhibit antitumor activity in mouse models. Development of these inhibitors could be dramatically accelerated by conferring tumor targeting and controlled release capability. As a first step towards this goal, we have encapsulated P61A6 into a new type of liposomes that open and release cargos only under low pH condition. These low pH-release type liposomes were prepared by adjusting the ratio of two types of phospholipid derivatives. Loading of geranylgeranyltransferase-I inhibitor (GGTI) generated liposomes with average diameter of 50-100 nm. GGTI release in solution was sharply dependent on pH values, only showing release at pH lower than 6. Release of cargos in a pH-dependent manner inside the cell was demonstrated by the use of a proton pump inhibitor Bafilomycin A1 that Increased lysosomal pH and inhibited the release of a dye carried in the pH-liposome. Delivery of GGTI to human pancreatic cancer cells was demonstrated by the inhibition of protein geranylgeranylation inside the cell and this effect was blocked by Bafilomycin A1. In addition, GGTI delivered by pH-liposomes induced proliferation inhibition, G1 cell cycle arrest that is associated with the expression of cell cycle regulator p21CIP1/WAF1. Proliferation inhibition was also observed with various lung cancer cell lines. Availability of nanoformulated GGTI opens up the possibility to combine with other types of inhibitors. To demonstrate this point, we combined the liposomal-GGTI with farnesyltransferase inhibitor (FTI) to inhibit K-Ras signaling in pancreatic cancer cells. Our results show that the activated K-Ras signaling in these cells can be effectively inhibited and that synergistic effect of the two drugs is observed. Our results suggest a new direction in the use of GGTI for cancer therapy.

No MeSH data available.


Related in: MedlinePlus