Altered intracellular distribution of daunorubicin in immature acute myeloid leukemia cells

Abstract

We have used laser-assisted confocal microscopy to evaluate the intracellular distribution of daunorubicin (DNR) in acute myeloid leukemia (AML) cell lines and fresh AML cells according to their differentiation phenotype. In KG1a, KG1, TF-1 and HEL cells, which express the early differentiation marker CD34, DNR was distributed in perinuclear vesicles which could be associated with the Golgi apparatus, as suggested by the distribution of fluorescent probes specific for intracellular organelles. In contrast, U937 and HL-60 cells, which display a more mature phenotype, exhibited nuclear and diffuse cytoplasmic DNR fluorescence. DNR sequestration was not correlated with P-glycoprotein (P-gp) or multidrug resistance protein expression. Furthermore, PSC833, a potent P-gp blocker, had little effect on drug sequestration in CD34 1 AML cells. We also tested the effect of metabolic inhibitors, cytoskeleton inhibitors and carboxy-ionophores on DNR distribution in both CD34 2 and CD34 1 AML cells. However, only non-specific metabolic inhibitors restored nucleic/cytoplasmic distribution in CD34 1 cells. In these cells, the intracellular distribution of doxorubicin and idarubicin was very similar to that of DNR, while the distribution of methoxymorpholinyl-doxorubicin was nuclear and diffusely cytoplasmic. In fresh AML cells, DNR was also concentrated in the perinuclear region in CD34 1 but not in CD34 2 cells. However, DNR sequestration was not observed in normal CD34 1 cells. Finally, our results show that DNR is sequestered in organelles in CD34 1 AML cells via an active mechanism which appears to be different from P-gp-mediated transport. Abnormal DNR distribution may account for the natural resistance of immature AML cells to anthracyclines.

Acute Doxorubicin Insult in the Mouse Ovary Is Cell- and Follicle-Type Dependent

“…While the present study did not identify these subcellular compartments, DXR and other chemotherapy agents are found concentrated in perinuclear puncta identified as acidic organelles [61], [62], [63], [64], [65], [66], [67], [68], [69] including lysosomes [68], [70], [71], endosomes [68], and the Golgi [65], [68], [72], depending on the cell type. It is unclear whether these structures play a role in the apparent sensitivity of granulosa cells to DXR-induced DNA damage or are in fact a defense mechanism.…”

“…It is unclear whether these structures play a role in the apparent sensitivity of granulosa cells to DXR-induced DNA damage or are in fact a defense mechanism. One frequently observed feature of multidrug resistant cancer cells is compartmentalization of DXR and other chemotherapy agents into acidic intracellular compartments [31], [35], [61], [63], [65], [66], [67], [68], [69], [70], [71], [72], [73], [74], [75], [76], [77], [78], [79], [80], [81], [82], [83], [84], [85], [86], [87], [88], [89], [90], [91], [92], [93], [94], [95], [96], [97]; this compartmentalization is directly linked to limiting nuclear accumulation of DXR and therefore decreasing chemotherapy toxicity. Exceptions exist, however, such as the uterine drug-sensitive MES-SA cell line which accumulates DXR in lysosomes where the drug-resistant MES-SA/Dx5 cell line does not [76].…”

Cepharanthine potently enhances the sensitivity of anticancer agents in K562 cells

“…ADM localized in acidic organelles, such as lysosomes, the trans‐Golgi network and endosomes, has been observed in drug‐resistant cells. ( 3–7 ) In these cells, weak base chemotherapeutics accumulated in acidic organelles and sequestered from their molecular targets in the cytosol and nuclei. ( 25 ) Cepharanthine blocked the acidification of organelles in K562 cells, and ADM may have been consequently released from the organelles into the nucleus.…”

“…Cellular pH in tumor‐derived cells was measured in several studies. The vesicles in which drugs accumulated have been identified as lysosomes, ( 3,4 ) endosomes, ( 5 ) and vesicles of the Golgi compartment, ( 6,7 ) all of which are acidic organelles. Many anticancer agents, such as doxorubicin (ADM), daunorubin, vincristine (VCR), and mitoxantrone, are weak bases with pK a values between 7.4 and 8.4.…”

Drug sequestration in cytoplasmic organelles does not contribute to the diminished sensitivity of anthracyclines in multidrug resistant K562 cells

“…Logically, any weakly basic compound will tend to accumulate in any membrane‐bound compartment that has a lower internal pH than external pH. Previous studies have indicated that drugs accumulate in Golgi‐derived vesicles [13,31,32], endosomes [13] and lysosomes [13,33,34]: all of which are more acidic than the cytosol. The cytosol of most cells has a pH of 7.2–7.3, by contrast, the lumena of recycling endosomes and trans ‐Golgi network have a pH of 6.0–6.3, and the pH of lysosomes can be lower than 4.5.…”