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Lysosomal sequestration of hydrophobic weak base chemotherapeutics triggers lysosomal biogenesis and lysosome-dependent cancer multidrug resistance.

Zhitomirsky B, Assaraf YG - Oncotarget (2015)

Bottom Line: Non-cytotoxic, nanomolar concentrations, of the hydrophobic weak base chemotherapeutics doxorubicin and mitoxantrone triggered rapid lysosomal biogenesis that was associated with nuclear translocation of TFEB, the dominant transcription factor regulating lysosomal biogenesis.This resulted in increased lysosomal gene expression and lysosomal enzyme activity.The current study provides the first evidence that drug-induced TFEB-associated lysosomal biogenesis is an emerging determinant of MDR and suggests that circumvention of lysosomal drug sequestration is a novel strategy to overcome this chemoresistance.

View Article: PubMed Central - PubMed

Affiliation: The Fred Wyszkowski Cancer Research Laboratory, Dept. of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.

ABSTRACT
Multidrug resistance (MDR) is a primary hindrance to curative cancer chemotherapy. In this respect, lysosomes were suggested to play a role in intrinsic MDR by sequestering protonated hydrophobic weak base chemotherapeutics away from their intracellular target sites. Here we show that intrinsic resistance to sunitinib, a hydrophobic weak base tyrosine kinase inhibitor known to accumulate in lysosomes, tightly correlates with the number of lysosomes accumulating high levels of sunitinib in multiple human carcinoma cells. Furthermore, exposure of cancer cells to hydrophobic weak base drugs leads to a marked increase in the number of lysosomes per cell. Non-cytotoxic, nanomolar concentrations, of the hydrophobic weak base chemotherapeutics doxorubicin and mitoxantrone triggered rapid lysosomal biogenesis that was associated with nuclear translocation of TFEB, the dominant transcription factor regulating lysosomal biogenesis. This resulted in increased lysosomal gene expression and lysosomal enzyme activity. Thus, treatment of cancer cells with hydrophobic weak base chemotherapeutics and their consequent sequestration in lysosomes triggers lysosomal biogenesis, thereby further enhancing lysosomal drug entrapment and MDR. The current study provides the first evidence that drug-induced TFEB-associated lysosomal biogenesis is an emerging determinant of MDR and suggests that circumvention of lysosomal drug sequestration is a novel strategy to overcome this chemoresistance.

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Mitoxantrone induces an increase in lysosomal enzyme activity in a drug dose-dependent mannerβ-Hexosaminidase activity was determined in MCF-7 cells after their exposure to increasing concentrations of mitoxantrone for 24 hr (A) or 72 hr (B). Statistical significance is denoted by *(p < 0.05).
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Figure 6: Mitoxantrone induces an increase in lysosomal enzyme activity in a drug dose-dependent mannerβ-Hexosaminidase activity was determined in MCF-7 cells after their exposure to increasing concentrations of mitoxantrone for 24 hr (A) or 72 hr (B). Statistical significance is denoted by *(p < 0.05).

Mentions: We next assessed whether or not the increases in both the mRNA levels of these lysosomal markers as well as in lysosome number per cell were associated with a consistent increase in the catalytic activity of the established lysosomal enzyme β-hexosaminidase. We have previously shown that β-hexosaminidase is a bona fide functional marker of the number of lysosomes per cell [29]. MCF-7 cells were exposed to increasing concentrations of mitoxantrone, followed by extraction of cell lysates and determination of β-hexosaminidase activity. A dose-dependent increase in β-hexosaminidase activity was induced by mitoxantrone concentrations as low as 30 nM after 24 hr drug exposure (Fig. 6A). After 72 hr of drug exposure, the increase in β-hexosaminidase activity was evident at drug concentrations as low as 10 nM (Fig. 6B).


Lysosomal sequestration of hydrophobic weak base chemotherapeutics triggers lysosomal biogenesis and lysosome-dependent cancer multidrug resistance.

Zhitomirsky B, Assaraf YG - Oncotarget (2015)

Mitoxantrone induces an increase in lysosomal enzyme activity in a drug dose-dependent mannerβ-Hexosaminidase activity was determined in MCF-7 cells after their exposure to increasing concentrations of mitoxantrone for 24 hr (A) or 72 hr (B). Statistical significance is denoted by *(p < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4359223&req=5

Figure 6: Mitoxantrone induces an increase in lysosomal enzyme activity in a drug dose-dependent mannerβ-Hexosaminidase activity was determined in MCF-7 cells after their exposure to increasing concentrations of mitoxantrone for 24 hr (A) or 72 hr (B). Statistical significance is denoted by *(p < 0.05).
Mentions: We next assessed whether or not the increases in both the mRNA levels of these lysosomal markers as well as in lysosome number per cell were associated with a consistent increase in the catalytic activity of the established lysosomal enzyme β-hexosaminidase. We have previously shown that β-hexosaminidase is a bona fide functional marker of the number of lysosomes per cell [29]. MCF-7 cells were exposed to increasing concentrations of mitoxantrone, followed by extraction of cell lysates and determination of β-hexosaminidase activity. A dose-dependent increase in β-hexosaminidase activity was induced by mitoxantrone concentrations as low as 30 nM after 24 hr drug exposure (Fig. 6A). After 72 hr of drug exposure, the increase in β-hexosaminidase activity was evident at drug concentrations as low as 10 nM (Fig. 6B).

Bottom Line: Non-cytotoxic, nanomolar concentrations, of the hydrophobic weak base chemotherapeutics doxorubicin and mitoxantrone triggered rapid lysosomal biogenesis that was associated with nuclear translocation of TFEB, the dominant transcription factor regulating lysosomal biogenesis.This resulted in increased lysosomal gene expression and lysosomal enzyme activity.The current study provides the first evidence that drug-induced TFEB-associated lysosomal biogenesis is an emerging determinant of MDR and suggests that circumvention of lysosomal drug sequestration is a novel strategy to overcome this chemoresistance.

View Article: PubMed Central - PubMed

Affiliation: The Fred Wyszkowski Cancer Research Laboratory, Dept. of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.

ABSTRACT
Multidrug resistance (MDR) is a primary hindrance to curative cancer chemotherapy. In this respect, lysosomes were suggested to play a role in intrinsic MDR by sequestering protonated hydrophobic weak base chemotherapeutics away from their intracellular target sites. Here we show that intrinsic resistance to sunitinib, a hydrophobic weak base tyrosine kinase inhibitor known to accumulate in lysosomes, tightly correlates with the number of lysosomes accumulating high levels of sunitinib in multiple human carcinoma cells. Furthermore, exposure of cancer cells to hydrophobic weak base drugs leads to a marked increase in the number of lysosomes per cell. Non-cytotoxic, nanomolar concentrations, of the hydrophobic weak base chemotherapeutics doxorubicin and mitoxantrone triggered rapid lysosomal biogenesis that was associated with nuclear translocation of TFEB, the dominant transcription factor regulating lysosomal biogenesis. This resulted in increased lysosomal gene expression and lysosomal enzyme activity. Thus, treatment of cancer cells with hydrophobic weak base chemotherapeutics and their consequent sequestration in lysosomes triggers lysosomal biogenesis, thereby further enhancing lysosomal drug entrapment and MDR. The current study provides the first evidence that drug-induced TFEB-associated lysosomal biogenesis is an emerging determinant of MDR and suggests that circumvention of lysosomal drug sequestration is a novel strategy to overcome this chemoresistance.

Show MeSH
Related in: MedlinePlus