Limits...
The Na⁺/H⁺ exchanger (NHE1) as a novel co-adjuvant target in paclitaxel therapy of triple-negative breast cancer cells.

Amith SR, Wilkinson JM, Baksh S, Fliegel L - Oncotarget (2015)

Bottom Line: In vivo xenograft tumor growth in athymic nude mice was also dramatically decreased compared to parental MDA-MB-231 cells.Loss of NHE1 expression also increased the susceptibility of knockout cells to paclitaxel-mediated cell death.NHE1 inhibition, in combination with paclitaxel, resulted in a dramatic decrease in viability, and migratory and invasive potential of triple-negative breast cancer cells, but not in hormone receptor-positive, luminal MCF7 cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada.

ABSTRACT
Dysregulation of Na⁺/H⁺ exchanger isoform one (NHE1) activity is a hallmark of cells undergoing tumorigenesis and metastasis, the leading cause of patient mortality. The acidic tumor microenvironment is thought to facilitate the development of resistance to chemotherapy drugs and to promote extracellular matrix remodeling leading to metastasis. Here, we investigated NHE1 as a co-adjuvant target in paclitaxel chemotherapy of metastatic breast cancer. We generated a stable NHE1-knockout of the highly invasive, triple-negative, MDA-MB-231 breast cancer cells. The NHE1-knockout cells proliferated comparably to parental cells, but had markedly lower rates of migration and invasion in vitro. In vivo xenograft tumor growth in athymic nude mice was also dramatically decreased compared to parental MDA-MB-231 cells. Loss of NHE1 expression also increased the susceptibility of knockout cells to paclitaxel-mediated cell death. NHE1 inhibition, in combination with paclitaxel, resulted in a dramatic decrease in viability, and migratory and invasive potential of triple-negative breast cancer cells, but not in hormone receptor-positive, luminal MCF7 cells. Our data suggest that NHE1 is critical in triple-negative breast cancer metastasis, and its chemical inhibition boosts the efficacy of paclitaxel in vitro, highlighting NHE1 as a novel, potential co-adjuvant target in breast cancer chemotherapy.

Show MeSH

Related in: MedlinePlus

Effect of paclitaxel in combination with NHE1 inhibitors on cell migration of wild type (WT) and NHE1-knockout (KO) MDA-MB-231, MDA-MB-468 (468) and MCF7 cellsThe rate of closure of an induced gap was evaluated using a qualitative wound-healing assay as described in the Materials and Methods. A, Rate of gap closure in stimulated (STIM) (0.2% serum) and unstimulated (UNSTIM) (10% serum) 231-KO cells relative to 231-WT cells, and in comparison to MDA-MB-468 and MCF7 cells. Stimulated 231-WT and MDA-MB-468 cells migrate faster than unstimulated cells [*P<0.001, # P<0.05, N=10]. In contrast, in 231-KO cells, faster migration is observed in unstimulated conditions [*P<0.001, N=10]. B, Pictorial representation of gap closure (at 10X magnification) in serum-deprived 231-WT and 231-KO cells over time. C, Combined effect of paclitaxel and NHE1 inhibitors on the rate of migration. 1 nM paclitaxel (TAX) was evaluated in combination with either HMA (10 nM) or EMD87580 (10 μM). Arbitrary measurements of gap closure (normalized to the untreated controls) were pooled over multiple independent experiments and quantified with Image Pro Plus software [*P<0.001, + P<0.01, # P<0.05, N=10]. D, Pictorial representation of gap closure (at 10X magnification) in serum-deprived 231-WT cells treated with paclitaxel, either alone or in combination with EMD87580 or HMA at 18 hr.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4359231&req=5

Figure 5: Effect of paclitaxel in combination with NHE1 inhibitors on cell migration of wild type (WT) and NHE1-knockout (KO) MDA-MB-231, MDA-MB-468 (468) and MCF7 cellsThe rate of closure of an induced gap was evaluated using a qualitative wound-healing assay as described in the Materials and Methods. A, Rate of gap closure in stimulated (STIM) (0.2% serum) and unstimulated (UNSTIM) (10% serum) 231-KO cells relative to 231-WT cells, and in comparison to MDA-MB-468 and MCF7 cells. Stimulated 231-WT and MDA-MB-468 cells migrate faster than unstimulated cells [*P<0.001, # P<0.05, N=10]. In contrast, in 231-KO cells, faster migration is observed in unstimulated conditions [*P<0.001, N=10]. B, Pictorial representation of gap closure (at 10X magnification) in serum-deprived 231-WT and 231-KO cells over time. C, Combined effect of paclitaxel and NHE1 inhibitors on the rate of migration. 1 nM paclitaxel (TAX) was evaluated in combination with either HMA (10 nM) or EMD87580 (10 μM). Arbitrary measurements of gap closure (normalized to the untreated controls) were pooled over multiple independent experiments and quantified with Image Pro Plus software [*P<0.001, + P<0.01, # P<0.05, N=10]. D, Pictorial representation of gap closure (at 10X magnification) in serum-deprived 231-WT cells treated with paclitaxel, either alone or in combination with EMD87580 or HMA at 18 hr.

Mentions: We next examined the effect of NHE1 inhibition, in combination with paclitaxel, on cell migration in the three breast cancer cell lines. Stimulated (0.2% serum) 231-WT cells, migrated at a rate approximately 20% faster than unstimulated (10% serum) cells at 18 hr. post-scratch (P<0.001, N=10, Fig. 5A, B), whereas stimulated MDA-MB-468 cells migrated at about 10% faster than unstimulated cells (P<0.01, N=10). No differences were observed in MCF7 migration between stimulated and unstimulated cells. Interestingly, unstimulated 231-KO cells migrated faster than stimulated cells (P<0.05, N=10), a reversal of what is observed with the 231-WT. There was no difference in the rate of migration between unstimulated parental and NHE1-knockout MDA-MB-231 cells. Notably, when stimulated 231-WT or MDA-MB-468 cells were treated with paclitaxel in combination with either NHE1 inhibitor EMD87580 or HMA, a marked decrease in migration was observed (P<0.001, N=10, Fig. 5C, D). However, no such effect of drug treatments was seen in stimulated 231-KO or MCF7 cells, or in any cell type in unstimulated conditions (not shown).


The Na⁺/H⁺ exchanger (NHE1) as a novel co-adjuvant target in paclitaxel therapy of triple-negative breast cancer cells.

Amith SR, Wilkinson JM, Baksh S, Fliegel L - Oncotarget (2015)

Effect of paclitaxel in combination with NHE1 inhibitors on cell migration of wild type (WT) and NHE1-knockout (KO) MDA-MB-231, MDA-MB-468 (468) and MCF7 cellsThe rate of closure of an induced gap was evaluated using a qualitative wound-healing assay as described in the Materials and Methods. A, Rate of gap closure in stimulated (STIM) (0.2% serum) and unstimulated (UNSTIM) (10% serum) 231-KO cells relative to 231-WT cells, and in comparison to MDA-MB-468 and MCF7 cells. Stimulated 231-WT and MDA-MB-468 cells migrate faster than unstimulated cells [*P<0.001, # P<0.05, N=10]. In contrast, in 231-KO cells, faster migration is observed in unstimulated conditions [*P<0.001, N=10]. B, Pictorial representation of gap closure (at 10X magnification) in serum-deprived 231-WT and 231-KO cells over time. C, Combined effect of paclitaxel and NHE1 inhibitors on the rate of migration. 1 nM paclitaxel (TAX) was evaluated in combination with either HMA (10 nM) or EMD87580 (10 μM). Arbitrary measurements of gap closure (normalized to the untreated controls) were pooled over multiple independent experiments and quantified with Image Pro Plus software [*P<0.001, + P<0.01, # P<0.05, N=10]. D, Pictorial representation of gap closure (at 10X magnification) in serum-deprived 231-WT cells treated with paclitaxel, either alone or in combination with EMD87580 or HMA at 18 hr.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4359231&req=5

Figure 5: Effect of paclitaxel in combination with NHE1 inhibitors on cell migration of wild type (WT) and NHE1-knockout (KO) MDA-MB-231, MDA-MB-468 (468) and MCF7 cellsThe rate of closure of an induced gap was evaluated using a qualitative wound-healing assay as described in the Materials and Methods. A, Rate of gap closure in stimulated (STIM) (0.2% serum) and unstimulated (UNSTIM) (10% serum) 231-KO cells relative to 231-WT cells, and in comparison to MDA-MB-468 and MCF7 cells. Stimulated 231-WT and MDA-MB-468 cells migrate faster than unstimulated cells [*P<0.001, # P<0.05, N=10]. In contrast, in 231-KO cells, faster migration is observed in unstimulated conditions [*P<0.001, N=10]. B, Pictorial representation of gap closure (at 10X magnification) in serum-deprived 231-WT and 231-KO cells over time. C, Combined effect of paclitaxel and NHE1 inhibitors on the rate of migration. 1 nM paclitaxel (TAX) was evaluated in combination with either HMA (10 nM) or EMD87580 (10 μM). Arbitrary measurements of gap closure (normalized to the untreated controls) were pooled over multiple independent experiments and quantified with Image Pro Plus software [*P<0.001, + P<0.01, # P<0.05, N=10]. D, Pictorial representation of gap closure (at 10X magnification) in serum-deprived 231-WT cells treated with paclitaxel, either alone or in combination with EMD87580 or HMA at 18 hr.
Mentions: We next examined the effect of NHE1 inhibition, in combination with paclitaxel, on cell migration in the three breast cancer cell lines. Stimulated (0.2% serum) 231-WT cells, migrated at a rate approximately 20% faster than unstimulated (10% serum) cells at 18 hr. post-scratch (P<0.001, N=10, Fig. 5A, B), whereas stimulated MDA-MB-468 cells migrated at about 10% faster than unstimulated cells (P<0.01, N=10). No differences were observed in MCF7 migration between stimulated and unstimulated cells. Interestingly, unstimulated 231-KO cells migrated faster than stimulated cells (P<0.05, N=10), a reversal of what is observed with the 231-WT. There was no difference in the rate of migration between unstimulated parental and NHE1-knockout MDA-MB-231 cells. Notably, when stimulated 231-WT or MDA-MB-468 cells were treated with paclitaxel in combination with either NHE1 inhibitor EMD87580 or HMA, a marked decrease in migration was observed (P<0.001, N=10, Fig. 5C, D). However, no such effect of drug treatments was seen in stimulated 231-KO or MCF7 cells, or in any cell type in unstimulated conditions (not shown).

Bottom Line: In vivo xenograft tumor growth in athymic nude mice was also dramatically decreased compared to parental MDA-MB-231 cells.Loss of NHE1 expression also increased the susceptibility of knockout cells to paclitaxel-mediated cell death.NHE1 inhibition, in combination with paclitaxel, resulted in a dramatic decrease in viability, and migratory and invasive potential of triple-negative breast cancer cells, but not in hormone receptor-positive, luminal MCF7 cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada.

ABSTRACT
Dysregulation of Na⁺/H⁺ exchanger isoform one (NHE1) activity is a hallmark of cells undergoing tumorigenesis and metastasis, the leading cause of patient mortality. The acidic tumor microenvironment is thought to facilitate the development of resistance to chemotherapy drugs and to promote extracellular matrix remodeling leading to metastasis. Here, we investigated NHE1 as a co-adjuvant target in paclitaxel chemotherapy of metastatic breast cancer. We generated a stable NHE1-knockout of the highly invasive, triple-negative, MDA-MB-231 breast cancer cells. The NHE1-knockout cells proliferated comparably to parental cells, but had markedly lower rates of migration and invasion in vitro. In vivo xenograft tumor growth in athymic nude mice was also dramatically decreased compared to parental MDA-MB-231 cells. Loss of NHE1 expression also increased the susceptibility of knockout cells to paclitaxel-mediated cell death. NHE1 inhibition, in combination with paclitaxel, resulted in a dramatic decrease in viability, and migratory and invasive potential of triple-negative breast cancer cells, but not in hormone receptor-positive, luminal MCF7 cells. Our data suggest that NHE1 is critical in triple-negative breast cancer metastasis, and its chemical inhibition boosts the efficacy of paclitaxel in vitro, highlighting NHE1 as a novel, potential co-adjuvant target in breast cancer chemotherapy.

Show MeSH
Related in: MedlinePlus