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Giant Lysosomes as a Chemotherapy Resistance Mechanism in Hepatocellular Carcinoma Cells.

Colombo F, Trombetta E, Cetrangolo P, Maggioni M, Razini P, De Santis F, Torrente Y, Prati D, Torresani E, Porretti L - PLoS ONE (2014)

Bottom Line: ABC expression analyses showed that the main ABC protein harboured by all of the cell lines was PGP, whose expression was not limited to the cell membrane but was also found on lysosomes.The findings of this study demonstrate the involvement of PGP-positive lysosomes in drug sequestration and MDR in HCC cell lines.The possibility of modulating this mechanism using PGP inhibitors could lead to the development of new targeted strategies to enhance HCC treatment.

View Article: PubMed Central - PubMed

Affiliation: Clinical Chemistry and Microbiology Laboratory, Flow Cytometry and Experimental Hepatology Service, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.

ABSTRACT
Despite continuous improvements in therapeutic protocols, cancer-related mortality is still one of the main problems facing public health. The main cause of treatment failure is multi-drug resistance (MDR: simultaneous insensitivity to different anti-cancer agents), the underlying molecular and biological mechanisms of which include the activity of ATP binding cassette (ABC) proteins and drug compartmentalisation in cell organelles. We investigated the expression of the main ABC proteins and the role of cytoplasmic vacuoles in the MDR of six hepatocellular carcinoma (HCC) cell lines, and confirmed the accumulation of the yellow anti-cancer drug sunitinib in giant (four lines) and small cytoplasmic vacuoles of lysosomal origin (two lines). ABC expression analyses showed that the main ABC protein harboured by all of the cell lines was PGP, whose expression was not limited to the cell membrane but was also found on lysosomes. MTT assays showed that the cell lines with giant lysosomes were more resistant to sorafenib treatment than those with small lysosomes (p<0.01), and that verapamil incubation can revert this resistance, especially if it is administered after drug pre-incubation. The findings of this study demonstrate the involvement of PGP-positive lysosomes in drug sequestration and MDR in HCC cell lines. The possibility of modulating this mechanism using PGP inhibitors could lead to the development of new targeted strategies to enhance HCC treatment.

No MeSH data available.


Related in: MedlinePlus

Hypothesised mechanism of the enhanced efficacy of drug pre-treatment before verapamil administration and PGP blockade.A) HCC cells expressing active PGP can expel a drug (e.g. sunitinib) from the cytoplasm or store it in lysosomes. B) Blocking PGP with verapamil before the co-administration sunitinib and verapamil allows the drugs to enter the cell and diffuse into cytoplasm/nucleus. C) If sunitinib is used for pre-treatment, it is stored in giant lysosomes and, after the co-administration of sunitinib and verapamil and subsequent PGP blockade, the drugs can enter the cytoplasm/nucleus from both extra-cellular space and the lysosomes.
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pone-0114787-g011: Hypothesised mechanism of the enhanced efficacy of drug pre-treatment before verapamil administration and PGP blockade.A) HCC cells expressing active PGP can expel a drug (e.g. sunitinib) from the cytoplasm or store it in lysosomes. B) Blocking PGP with verapamil before the co-administration sunitinib and verapamil allows the drugs to enter the cell and diffuse into cytoplasm/nucleus. C) If sunitinib is used for pre-treatment, it is stored in giant lysosomes and, after the co-administration of sunitinib and verapamil and subsequent PGP blockade, the drugs can enter the cytoplasm/nucleus from both extra-cellular space and the lysosomes.

Mentions: Unexpectedly, pre-incubation with sorafenib before co-incubation with verapamil increased drug efficacy in the HCC cell lines with giant lysosomes. We hypothesise that, during the pre-incubation phase, anti-cancer drugs are trapped in PGP-positive lysosomes and that blocking PGP activity by means of subsequent drug/verapamil co-incubation would allow drug diffusion from the culture medium and lysosome into the cytoplasm, thus increasing intra-cellular drug concentrations (Fig. 11). On the contrary, the pre-treatments with both sunitinib or NH4CL showed the same increment in drug efficacy as compare to drug alone. This could be due to the absence of verapamil action on cell membrane PGP activity which leads to drug accumulation in the cytoplasm with a strong impact on cell viability.


Giant Lysosomes as a Chemotherapy Resistance Mechanism in Hepatocellular Carcinoma Cells.

Colombo F, Trombetta E, Cetrangolo P, Maggioni M, Razini P, De Santis F, Torrente Y, Prati D, Torresani E, Porretti L - PLoS ONE (2014)

Hypothesised mechanism of the enhanced efficacy of drug pre-treatment before verapamil administration and PGP blockade.A) HCC cells expressing active PGP can expel a drug (e.g. sunitinib) from the cytoplasm or store it in lysosomes. B) Blocking PGP with verapamil before the co-administration sunitinib and verapamil allows the drugs to enter the cell and diffuse into cytoplasm/nucleus. C) If sunitinib is used for pre-treatment, it is stored in giant lysosomes and, after the co-administration of sunitinib and verapamil and subsequent PGP blockade, the drugs can enter the cytoplasm/nucleus from both extra-cellular space and the lysosomes.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4262459&req=5

pone-0114787-g011: Hypothesised mechanism of the enhanced efficacy of drug pre-treatment before verapamil administration and PGP blockade.A) HCC cells expressing active PGP can expel a drug (e.g. sunitinib) from the cytoplasm or store it in lysosomes. B) Blocking PGP with verapamil before the co-administration sunitinib and verapamil allows the drugs to enter the cell and diffuse into cytoplasm/nucleus. C) If sunitinib is used for pre-treatment, it is stored in giant lysosomes and, after the co-administration of sunitinib and verapamil and subsequent PGP blockade, the drugs can enter the cytoplasm/nucleus from both extra-cellular space and the lysosomes.
Mentions: Unexpectedly, pre-incubation with sorafenib before co-incubation with verapamil increased drug efficacy in the HCC cell lines with giant lysosomes. We hypothesise that, during the pre-incubation phase, anti-cancer drugs are trapped in PGP-positive lysosomes and that blocking PGP activity by means of subsequent drug/verapamil co-incubation would allow drug diffusion from the culture medium and lysosome into the cytoplasm, thus increasing intra-cellular drug concentrations (Fig. 11). On the contrary, the pre-treatments with both sunitinib or NH4CL showed the same increment in drug efficacy as compare to drug alone. This could be due to the absence of verapamil action on cell membrane PGP activity which leads to drug accumulation in the cytoplasm with a strong impact on cell viability.

Bottom Line: ABC expression analyses showed that the main ABC protein harboured by all of the cell lines was PGP, whose expression was not limited to the cell membrane but was also found on lysosomes.The findings of this study demonstrate the involvement of PGP-positive lysosomes in drug sequestration and MDR in HCC cell lines.The possibility of modulating this mechanism using PGP inhibitors could lead to the development of new targeted strategies to enhance HCC treatment.

View Article: PubMed Central - PubMed

Affiliation: Clinical Chemistry and Microbiology Laboratory, Flow Cytometry and Experimental Hepatology Service, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.

ABSTRACT
Despite continuous improvements in therapeutic protocols, cancer-related mortality is still one of the main problems facing public health. The main cause of treatment failure is multi-drug resistance (MDR: simultaneous insensitivity to different anti-cancer agents), the underlying molecular and biological mechanisms of which include the activity of ATP binding cassette (ABC) proteins and drug compartmentalisation in cell organelles. We investigated the expression of the main ABC proteins and the role of cytoplasmic vacuoles in the MDR of six hepatocellular carcinoma (HCC) cell lines, and confirmed the accumulation of the yellow anti-cancer drug sunitinib in giant (four lines) and small cytoplasmic vacuoles of lysosomal origin (two lines). ABC expression analyses showed that the main ABC protein harboured by all of the cell lines was PGP, whose expression was not limited to the cell membrane but was also found on lysosomes. MTT assays showed that the cell lines with giant lysosomes were more resistant to sorafenib treatment than those with small lysosomes (p<0.01), and that verapamil incubation can revert this resistance, especially if it is administered after drug pre-incubation. The findings of this study demonstrate the involvement of PGP-positive lysosomes in drug sequestration and MDR in HCC cell lines. The possibility of modulating this mechanism using PGP inhibitors could lead to the development of new targeted strategies to enhance HCC treatment.

No MeSH data available.


Related in: MedlinePlus