Limits...
Induction of acquired drug resistance in endothelial cells and its involvement in anticancer therapy.

Huang L, Perrault C, Coelho-Martins J, Hu C, Dulong C, Varna M, Liu J, Jin J, Soria C, Cazin L, Janin A, Li H, Varin R, Lu H - J Hematol Oncol (2013)

Bottom Line: Drug resistance in HMEC-1 and HUVEC was successfully induced by the addition of Dox to the culture media.ABC transporter expression can be induced in endothelial cells in vitro.This study also indicates that P-gp plays an important role in the acquisition of resistance to Dox in endothelial cells and that this reduces the efficiency of chemotherapy.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Multidrug resistance (MDR) is one of the major problems in the treatment of cancer. Overcoming it is therefore expected to improve clinical outcomes for cancer patients. MDR is usually characterized by overexpression of ABC (ATP-binding cassette) protein transporters such as P-gp, MRP1, and ABCG2. Though the importance of ABC transporters for cancer cells is recognized, few studies have looked at its implications for the endothelial cells that are essential to tumor angiogenesis. This study investigated the expression and functions of these ABC transporters in endothelial cells in vitro and their potential contribution to cancer growth in mice.

Methods: Human micro vessel endothelial cells (HMEC-1) and human umbilical vein endothelial cells (HUVEC) were exposed to increasing doses of Doxorubicin (Dox) to induce ABC gene expression. Cell viability was then quantified by (3)H-thymidine and MTS assay. Flow cytometry, qPCR, and western blot were used to detect mRNA and the protein expression of P-gp, MRP1, and ABCG2. The intracellular accumulation of Rhodamine 123 (Rho) was used to evaluate drug efflux function and the inhibitors for P-gp, ABCG2, and MRP1 were used to verify their respective roles in vitro. In an attempt to evaluate drug resistance in endothelial cells in vivo, athymic mice were treated with Dox for 15 days before a MDA-MB-435 tumor graft to observe subsequent changes in the inhibition curves of tumor growth in response to Dox treatment. Furthermore, endothelial cells from multiple sites in these mice were also isolated to estimate their P-gp expression by flow cytometry.

Results: Drug resistance in HMEC-1 and HUVEC was successfully induced by the addition of Dox to the culture media. Two stabilized subcell lines of HMEC1 (HMECd1 and HMECd2) showed 15- and 24-fold increases in resistance. Tests also showed that these induced endothelial cells were cross-resistant to the structurally unrelated drugs Daunorubicin, Vinblastine, and Etoposide. P-gp protein levels increased four and six fold in HMECd1 and HMECd2 as revealed by western blot. The qPCR demonstrated 3.4- and 7.2-fold increases in P-gp, and a slight increase in ABCG2, gene expression. The Rho accumulation within these cells was inversely correlated with the expression levels of P-gp. The inhibitors of P-gp, but not of ABCG2 or MRP1, were able to block the induced endothelial cell resistance to Dox. Furthermore, we also showed that injecting Dox into healthy mice induced an increase in P-gp expression in endothelial cells. Using these pretreated mice in a tumor growth experiment, we observed a dramatic diminution in the therapeutic efficiency of Dox treatment, suggesting implications for drug resistance in mice endothelial cells supporting tumor growth.

Conclusions: ABC transporter expression can be induced in endothelial cells in vitro. This study also indicates that P-gp plays an important role in the acquisition of resistance to Dox in endothelial cells and that this reduces the efficiency of chemotherapy.

Show MeSH

Related in: MedlinePlus

Endothelial cells express functional P-gp protein. Panel a and b: Verapamil blocks Rho efflux in endothelial cells. Dox- or noninduced HMEC and HUVEC cells were incubated in the absence or presence of Rho for 1 hour at 37°C. Rho accumulation was inhibited by the addition of Verapamil (Vrp) at 30 μM to the cell incubation mixture. The cells were analyzed in the flow cytometer. Panel c and d: Activity of endothelial P-gp is blocked by Verapamil and MRK16. Parental HMEC, HMECd1, and HMECd2 cells were incubated with 1 μM (c) or 2 μM (d) Rho for 1 hour at 37°C in the absence or presence of 30 μM Verapamil or 10 μg/ml MRK16 (MRK). Rho accumulation was measured by flow cytometry and quantified as the MFI. The background fluorescence level, determined using cells not exposed to Rho, was subtracted from the data. Results are expressed as the mean±SEM of 3 separate experiments. *p < 0.025, **p < 0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3717049&req=5

Figure 2: Endothelial cells express functional P-gp protein. Panel a and b: Verapamil blocks Rho efflux in endothelial cells. Dox- or noninduced HMEC and HUVEC cells were incubated in the absence or presence of Rho for 1 hour at 37°C. Rho accumulation was inhibited by the addition of Verapamil (Vrp) at 30 μM to the cell incubation mixture. The cells were analyzed in the flow cytometer. Panel c and d: Activity of endothelial P-gp is blocked by Verapamil and MRK16. Parental HMEC, HMECd1, and HMECd2 cells were incubated with 1 μM (c) or 2 μM (d) Rho for 1 hour at 37°C in the absence or presence of 30 μM Verapamil or 10 μg/ml MRK16 (MRK). Rho accumulation was measured by flow cytometry and quantified as the MFI. The background fluorescence level, determined using cells not exposed to Rho, was subtracted from the data. Results are expressed as the mean±SEM of 3 separate experiments. *p < 0.025, **p < 0.01.

Mentions: Induced P-gp-mediated drug resistance of endothelial cells. P-gp cell surface expression was analyzed with flow cytometry in HMEC (Panel a) or HUVEC cells (Panel b). Endothelial cells expressed P-gp after the induction by Dox treatment. Parental (thick black line), HMECd1 and HUVECd3 (thin black line), and HMECd2 (−−) cells were incubated with 10 μg/ml 4E3. Incubation with control IgG2a gave similar histograms for the three cell lines (filled grey histogram). Histograms are representative of four separate experiments. Panel c: The western blot of P-gp levels in HMECd1, HMECd2 and their parental cells. The data for the ratio were obtained with three repeated blots. *: p < 0.05 in comparison with the controls. Panel d: The western blot of ABCG2 levels in these cells. The data for the ratio were obtained with three repeated blots. *: p < 0.05 versus the controls. Panel e: qPCR (primer Hs01067802_m1) results of P-gp mRNA levels in treated or nontreated HMEC-1, HMECd1, and HMECd2. Cyclosporine A (C), Verapamil (V), Fumitremorgin C (F), and Diethylstibesterol (D) were used to treat the cells. The results were obtained from three independent experiments. *: p < 0.05 versus the nontreated cells. Panel f: qPCR (Hs01053790_m1) results of ABCG2 mRNA levels in treated or nontreated HMEC-1, HMECd1, and HMECd2. Cyclosporine A (C), Verapamil (V), Fumitremorgin C (F), and Diethylstibesterol (D) were used to treat the cells. The results were obtained from three independent experiments. *: p < 0.05 versus the nontreated cells. Panel g: Correlation between P-gp surface expression and its efflux function. During the establishment of resistant HMEC cell lines, the P-gp surface expression and the Rho efflux were regularly analyzed by flow cytometry, as shown in Figure 2a-d (R2 = 0.9301).


Induction of acquired drug resistance in endothelial cells and its involvement in anticancer therapy.

Huang L, Perrault C, Coelho-Martins J, Hu C, Dulong C, Varna M, Liu J, Jin J, Soria C, Cazin L, Janin A, Li H, Varin R, Lu H - J Hematol Oncol (2013)

Endothelial cells express functional P-gp protein. Panel a and b: Verapamil blocks Rho efflux in endothelial cells. Dox- or noninduced HMEC and HUVEC cells were incubated in the absence or presence of Rho for 1 hour at 37°C. Rho accumulation was inhibited by the addition of Verapamil (Vrp) at 30 μM to the cell incubation mixture. The cells were analyzed in the flow cytometer. Panel c and d: Activity of endothelial P-gp is blocked by Verapamil and MRK16. Parental HMEC, HMECd1, and HMECd2 cells were incubated with 1 μM (c) or 2 μM (d) Rho for 1 hour at 37°C in the absence or presence of 30 μM Verapamil or 10 μg/ml MRK16 (MRK). Rho accumulation was measured by flow cytometry and quantified as the MFI. The background fluorescence level, determined using cells not exposed to Rho, was subtracted from the data. Results are expressed as the mean±SEM of 3 separate experiments. *p < 0.025, **p < 0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3717049&req=5

Figure 2: Endothelial cells express functional P-gp protein. Panel a and b: Verapamil blocks Rho efflux in endothelial cells. Dox- or noninduced HMEC and HUVEC cells were incubated in the absence or presence of Rho for 1 hour at 37°C. Rho accumulation was inhibited by the addition of Verapamil (Vrp) at 30 μM to the cell incubation mixture. The cells were analyzed in the flow cytometer. Panel c and d: Activity of endothelial P-gp is blocked by Verapamil and MRK16. Parental HMEC, HMECd1, and HMECd2 cells were incubated with 1 μM (c) or 2 μM (d) Rho for 1 hour at 37°C in the absence or presence of 30 μM Verapamil or 10 μg/ml MRK16 (MRK). Rho accumulation was measured by flow cytometry and quantified as the MFI. The background fluorescence level, determined using cells not exposed to Rho, was subtracted from the data. Results are expressed as the mean±SEM of 3 separate experiments. *p < 0.025, **p < 0.01.
Mentions: Induced P-gp-mediated drug resistance of endothelial cells. P-gp cell surface expression was analyzed with flow cytometry in HMEC (Panel a) or HUVEC cells (Panel b). Endothelial cells expressed P-gp after the induction by Dox treatment. Parental (thick black line), HMECd1 and HUVECd3 (thin black line), and HMECd2 (−−) cells were incubated with 10 μg/ml 4E3. Incubation with control IgG2a gave similar histograms for the three cell lines (filled grey histogram). Histograms are representative of four separate experiments. Panel c: The western blot of P-gp levels in HMECd1, HMECd2 and their parental cells. The data for the ratio were obtained with three repeated blots. *: p < 0.05 in comparison with the controls. Panel d: The western blot of ABCG2 levels in these cells. The data for the ratio were obtained with three repeated blots. *: p < 0.05 versus the controls. Panel e: qPCR (primer Hs01067802_m1) results of P-gp mRNA levels in treated or nontreated HMEC-1, HMECd1, and HMECd2. Cyclosporine A (C), Verapamil (V), Fumitremorgin C (F), and Diethylstibesterol (D) were used to treat the cells. The results were obtained from three independent experiments. *: p < 0.05 versus the nontreated cells. Panel f: qPCR (Hs01053790_m1) results of ABCG2 mRNA levels in treated or nontreated HMEC-1, HMECd1, and HMECd2. Cyclosporine A (C), Verapamil (V), Fumitremorgin C (F), and Diethylstibesterol (D) were used to treat the cells. The results were obtained from three independent experiments. *: p < 0.05 versus the nontreated cells. Panel g: Correlation between P-gp surface expression and its efflux function. During the establishment of resistant HMEC cell lines, the P-gp surface expression and the Rho efflux were regularly analyzed by flow cytometry, as shown in Figure 2a-d (R2 = 0.9301).

Bottom Line: Drug resistance in HMEC-1 and HUVEC was successfully induced by the addition of Dox to the culture media.ABC transporter expression can be induced in endothelial cells in vitro.This study also indicates that P-gp plays an important role in the acquisition of resistance to Dox in endothelial cells and that this reduces the efficiency of chemotherapy.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Multidrug resistance (MDR) is one of the major problems in the treatment of cancer. Overcoming it is therefore expected to improve clinical outcomes for cancer patients. MDR is usually characterized by overexpression of ABC (ATP-binding cassette) protein transporters such as P-gp, MRP1, and ABCG2. Though the importance of ABC transporters for cancer cells is recognized, few studies have looked at its implications for the endothelial cells that are essential to tumor angiogenesis. This study investigated the expression and functions of these ABC transporters in endothelial cells in vitro and their potential contribution to cancer growth in mice.

Methods: Human micro vessel endothelial cells (HMEC-1) and human umbilical vein endothelial cells (HUVEC) were exposed to increasing doses of Doxorubicin (Dox) to induce ABC gene expression. Cell viability was then quantified by (3)H-thymidine and MTS assay. Flow cytometry, qPCR, and western blot were used to detect mRNA and the protein expression of P-gp, MRP1, and ABCG2. The intracellular accumulation of Rhodamine 123 (Rho) was used to evaluate drug efflux function and the inhibitors for P-gp, ABCG2, and MRP1 were used to verify their respective roles in vitro. In an attempt to evaluate drug resistance in endothelial cells in vivo, athymic mice were treated with Dox for 15 days before a MDA-MB-435 tumor graft to observe subsequent changes in the inhibition curves of tumor growth in response to Dox treatment. Furthermore, endothelial cells from multiple sites in these mice were also isolated to estimate their P-gp expression by flow cytometry.

Results: Drug resistance in HMEC-1 and HUVEC was successfully induced by the addition of Dox to the culture media. Two stabilized subcell lines of HMEC1 (HMECd1 and HMECd2) showed 15- and 24-fold increases in resistance. Tests also showed that these induced endothelial cells were cross-resistant to the structurally unrelated drugs Daunorubicin, Vinblastine, and Etoposide. P-gp protein levels increased four and six fold in HMECd1 and HMECd2 as revealed by western blot. The qPCR demonstrated 3.4- and 7.2-fold increases in P-gp, and a slight increase in ABCG2, gene expression. The Rho accumulation within these cells was inversely correlated with the expression levels of P-gp. The inhibitors of P-gp, but not of ABCG2 or MRP1, were able to block the induced endothelial cell resistance to Dox. Furthermore, we also showed that injecting Dox into healthy mice induced an increase in P-gp expression in endothelial cells. Using these pretreated mice in a tumor growth experiment, we observed a dramatic diminution in the therapeutic efficiency of Dox treatment, suggesting implications for drug resistance in mice endothelial cells supporting tumor growth.

Conclusions: ABC transporter expression can be induced in endothelial cells in vitro. This study also indicates that P-gp plays an important role in the acquisition of resistance to Dox in endothelial cells and that this reduces the efficiency of chemotherapy.

Show MeSH
Related in: MedlinePlus