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Low molecular weight protein tyrosine phosphatase (LMWPTP) upregulation mediates malignant potential in colorectal cancer.

Hoekstra E, Kodach LL, Das AM, Ruela-de-Sousa RR, Ferreira CV, Hardwick JC, van der Woude CJ, Peppelenbosch MP, Ten Hagen TL, Fuhler GM - Oncotarget (2015)

Bottom Line: In the present study, we show that LMWPTP expression is not only significantly increased in colorectal cancer (CRC), but also follows a step-wise increase in different levels of dysplasia.Chemical inhibition of LMWPTP significantly reduces CRC growth.In conclusion, this study shows that LMWPTP is not only overexpressed in colorectal cancer, but it is correlated with the malignant potential of this cancer, suggesting that this phosphatase may act as a predictive biomaker of CRC stage and represents a rational novel target in the treatment of this disease.

View Article: PubMed Central - PubMed

Affiliation: Department of Gastroenterology and Hepatology, Erasmus MC, University Medical Center Rotterdam, 's Gravendijkwa, Rotterdam, The Netherlands.

ABSTRACT
Phosphatases have long been regarded as tumor suppressors, however there is emerging evidence for a tumor initiating role for some phosphatases in several forms of cancer. Low Molecular Weight Protein Tyrosine Phosphatase (LMWPTP; acid phosphatase 1 [ACP1]) is an 18 kDa enzyme that influences the phosphorylation of signaling pathway mediators involved in cancer and is thus postulated to be a tumor-promoting enzyme, but neither unequivocal clinical evidence nor convincing mechanistic actions for a role of LMWPTP have been identified. In the present study, we show that LMWPTP expression is not only significantly increased in colorectal cancer (CRC), but also follows a step-wise increase in different levels of dysplasia. Chemical inhibition of LMWPTP significantly reduces CRC growth. Furthermore, downregulation of LMWPTP in CRC leads to a reduced migration ability in both 2D- and 3D-migration assays, and sensitizes tumor cells to the chemotherapeutic agent 5-FU. In conclusion, this study shows that LMWPTP is not only overexpressed in colorectal cancer, but it is correlated with the malignant potential of this cancer, suggesting that this phosphatase may act as a predictive biomaker of CRC stage and represents a rational novel target in the treatment of this disease.

No MeSH data available.


Related in: MedlinePlus

LMWPTP influences cell survival pathways and desensitizes colorectal cancer cells to chemotherapy(A) Western blot analysis of LMWPTP knockdown and control cells reveals reduced phosphorylation of Epidermal Growth Factor Receptor (EGFR), Protein Kinase B (PKBt and PKBs) and FAK in the knockdown cells. (B) CACO-2 LMWPTP knockdown and control cells were treated with increasing concentrations of 5-fluorouracil and cell viability was assessed by MTT assay after 96 h. CACO-2 knockdown cells were more susceptible to 5-fluorouracil as compared to control (*P < 0.05). (C) P-glycoprotein expression on CACO-2 cells was determined by FACS analysis, using anti-P-gp and anti-mouse-FITC antibodies. P-gp expression is reduced upon LMWPTP knockdown in CACO-2 cells, as shown by FACS mean fluorescence intensity (MFI).
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Figure 4: LMWPTP influences cell survival pathways and desensitizes colorectal cancer cells to chemotherapy(A) Western blot analysis of LMWPTP knockdown and control cells reveals reduced phosphorylation of Epidermal Growth Factor Receptor (EGFR), Protein Kinase B (PKBt and PKBs) and FAK in the knockdown cells. (B) CACO-2 LMWPTP knockdown and control cells were treated with increasing concentrations of 5-fluorouracil and cell viability was assessed by MTT assay after 96 h. CACO-2 knockdown cells were more susceptible to 5-fluorouracil as compared to control (*P < 0.05). (C) P-glycoprotein expression on CACO-2 cells was determined by FACS analysis, using anti-P-gp and anti-mouse-FITC antibodies. P-gp expression is reduced upon LMWPTP knockdown in CACO-2 cells, as shown by FACS mean fluorescence intensity (MFI).

Mentions: Whilst not inducing cell death, knock down of LMWPTP in CRC lines allowed us to further investigate the role of LMWPTP in other oncogenic processes. We started by determining some of the molecular targets of LMWPTP. Figure 4A shows that knock down of LMWPTP resulted in the downregulation of several cancer-associated signaling pathways. Most noticeably, we observed a reduced phosphorylation of the epidermal growth factor receptor (EGFR) and diminished phosphorylation of protein kinase B (PKB) both on the threonine 308 and serine 473 sites in LMWPTP knockdown cells (Figure 4A). In addition to proliferation, these molecules are implicated in cell survival, and we therefor speculated that LMWPTP knockdown cells might be more susceptible to cytostatic agents. Indeed, treatment of CRC cells with 5-fluorouracil (5-FU), a commonly used chemotherapeutic, caused a dose dependent decrease in viable cell numbers, which was significantly more pronounced in LMWPTP knock down cells (Figure 4B and Supplementary Figure S3A). Thus, silencing of LMWPTP confers drug sensitivity of CRC cells, possibly through loss of EGFR and PKB activity. Other mechanisms used by tumor cells to escape drug effects include the expression and regulation of multidrug resistance efflux pumps. These include p-glycoprotein, also known as multidrug resistance protein 1 (MDR1), which transports several substrates across the extracellular membrane. Interestingly, P-gp was expressed on CACO-2 cells, and its expression was reduced upon silencing of LMWPTP (Figure 4C). In contrast, HCT116 cells did not express this particular efflux pump (and hence no decrease was observed in LMWPTP knock down cells), suggesting that different mechanisms may contribute to drug sensitivity in different CRC lines (Supplementary Figures S3B).


Low molecular weight protein tyrosine phosphatase (LMWPTP) upregulation mediates malignant potential in colorectal cancer.

Hoekstra E, Kodach LL, Das AM, Ruela-de-Sousa RR, Ferreira CV, Hardwick JC, van der Woude CJ, Peppelenbosch MP, Ten Hagen TL, Fuhler GM - Oncotarget (2015)

LMWPTP influences cell survival pathways and desensitizes colorectal cancer cells to chemotherapy(A) Western blot analysis of LMWPTP knockdown and control cells reveals reduced phosphorylation of Epidermal Growth Factor Receptor (EGFR), Protein Kinase B (PKBt and PKBs) and FAK in the knockdown cells. (B) CACO-2 LMWPTP knockdown and control cells were treated with increasing concentrations of 5-fluorouracil and cell viability was assessed by MTT assay after 96 h. CACO-2 knockdown cells were more susceptible to 5-fluorouracil as compared to control (*P < 0.05). (C) P-glycoprotein expression on CACO-2 cells was determined by FACS analysis, using anti-P-gp and anti-mouse-FITC antibodies. P-gp expression is reduced upon LMWPTP knockdown in CACO-2 cells, as shown by FACS mean fluorescence intensity (MFI).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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Figure 4: LMWPTP influences cell survival pathways and desensitizes colorectal cancer cells to chemotherapy(A) Western blot analysis of LMWPTP knockdown and control cells reveals reduced phosphorylation of Epidermal Growth Factor Receptor (EGFR), Protein Kinase B (PKBt and PKBs) and FAK in the knockdown cells. (B) CACO-2 LMWPTP knockdown and control cells were treated with increasing concentrations of 5-fluorouracil and cell viability was assessed by MTT assay after 96 h. CACO-2 knockdown cells were more susceptible to 5-fluorouracil as compared to control (*P < 0.05). (C) P-glycoprotein expression on CACO-2 cells was determined by FACS analysis, using anti-P-gp and anti-mouse-FITC antibodies. P-gp expression is reduced upon LMWPTP knockdown in CACO-2 cells, as shown by FACS mean fluorescence intensity (MFI).
Mentions: Whilst not inducing cell death, knock down of LMWPTP in CRC lines allowed us to further investigate the role of LMWPTP in other oncogenic processes. We started by determining some of the molecular targets of LMWPTP. Figure 4A shows that knock down of LMWPTP resulted in the downregulation of several cancer-associated signaling pathways. Most noticeably, we observed a reduced phosphorylation of the epidermal growth factor receptor (EGFR) and diminished phosphorylation of protein kinase B (PKB) both on the threonine 308 and serine 473 sites in LMWPTP knockdown cells (Figure 4A). In addition to proliferation, these molecules are implicated in cell survival, and we therefor speculated that LMWPTP knockdown cells might be more susceptible to cytostatic agents. Indeed, treatment of CRC cells with 5-fluorouracil (5-FU), a commonly used chemotherapeutic, caused a dose dependent decrease in viable cell numbers, which was significantly more pronounced in LMWPTP knock down cells (Figure 4B and Supplementary Figure S3A). Thus, silencing of LMWPTP confers drug sensitivity of CRC cells, possibly through loss of EGFR and PKB activity. Other mechanisms used by tumor cells to escape drug effects include the expression and regulation of multidrug resistance efflux pumps. These include p-glycoprotein, also known as multidrug resistance protein 1 (MDR1), which transports several substrates across the extracellular membrane. Interestingly, P-gp was expressed on CACO-2 cells, and its expression was reduced upon silencing of LMWPTP (Figure 4C). In contrast, HCT116 cells did not express this particular efflux pump (and hence no decrease was observed in LMWPTP knock down cells), suggesting that different mechanisms may contribute to drug sensitivity in different CRC lines (Supplementary Figures S3B).

Bottom Line: In the present study, we show that LMWPTP expression is not only significantly increased in colorectal cancer (CRC), but also follows a step-wise increase in different levels of dysplasia.Chemical inhibition of LMWPTP significantly reduces CRC growth.In conclusion, this study shows that LMWPTP is not only overexpressed in colorectal cancer, but it is correlated with the malignant potential of this cancer, suggesting that this phosphatase may act as a predictive biomaker of CRC stage and represents a rational novel target in the treatment of this disease.

View Article: PubMed Central - PubMed

Affiliation: Department of Gastroenterology and Hepatology, Erasmus MC, University Medical Center Rotterdam, 's Gravendijkwa, Rotterdam, The Netherlands.

ABSTRACT
Phosphatases have long been regarded as tumor suppressors, however there is emerging evidence for a tumor initiating role for some phosphatases in several forms of cancer. Low Molecular Weight Protein Tyrosine Phosphatase (LMWPTP; acid phosphatase 1 [ACP1]) is an 18 kDa enzyme that influences the phosphorylation of signaling pathway mediators involved in cancer and is thus postulated to be a tumor-promoting enzyme, but neither unequivocal clinical evidence nor convincing mechanistic actions for a role of LMWPTP have been identified. In the present study, we show that LMWPTP expression is not only significantly increased in colorectal cancer (CRC), but also follows a step-wise increase in different levels of dysplasia. Chemical inhibition of LMWPTP significantly reduces CRC growth. Furthermore, downregulation of LMWPTP in CRC leads to a reduced migration ability in both 2D- and 3D-migration assays, and sensitizes tumor cells to the chemotherapeutic agent 5-FU. In conclusion, this study shows that LMWPTP is not only overexpressed in colorectal cancer, but it is correlated with the malignant potential of this cancer, suggesting that this phosphatase may act as a predictive biomaker of CRC stage and represents a rational novel target in the treatment of this disease.

No MeSH data available.


Related in: MedlinePlus