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Effect of MUC1/ β -catenin interaction on the tumorigenic capacity of pancreatic CD133 + cells

View Article: PubMed Central - PubMed

ABSTRACT

Despite the fact that the biological function of cluster of differentiation (CD)133 remains unclear, this glycoprotein is currently used in the identification and isolation of tumor-initiating cells from certain malignant tumors, including pancreatic cancer. In the present study, the involvement of mucin 1 (MUC1) in the signaling pathways of a highly tumorigenic CD133+ cellular subpopulation sorted from the pancreatic cancer cell line HPAF-II was evaluated. The expression of MUC1-cytoplasmic domain (MUC1-CD) and oncogenic signaling transducers (epidermal growth factor receptor, protein kinase C delta, glycogen synthase kinase 3 beta and growth factor receptor-bound protein 2), as well as the association between MUC1 and β-catenin, were characterized in HPAF-II CD133+ and CD133low cell subpopulations and in tumor xenografts generated from these cells. Compared with HPAF CD133low cells, HPAF-II CD133+ cancer cells exhibited increased tumorigenic potential in immunocompromised mice, which was associated with overexpression of MUC1 and with the accordingly altered expression profile of MUC1-associated signaling partners. Additionally, MUC1-CD/β-catenin interactions were increased both in the HPAF-II CD133+ cell subpopulation and derived tumor xenografts compared with HPAF CD133low cells. These results suggest that, in comparison with HPAF CD133low cells, CD133+ cells exhibit higher expression of MUC1, which contributes to their tumorigenic phenotype through increased interaction between MUC1-CD and β-catenin, which in turn modulates oncogenic signaling cascades.

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Evaluation of MUC1/β-catenin interaction in HPAF-II cells and xenografts. (A) β-catenin expression and its interaction with MUC1-CD in HPAF-II wt, HPAF-II CD133low and HPAF-II CD133+ cells was evaluated by immunoprecipitation and western blot analysis. β-actin was used as a loading control. (B) In situ PLA in tumor xenografts was used to evaluate the interaction between MUC1 and β-catenin; magnification, (a) ×400; (b) ×650 (Duolink in situ Detection Reagents Brightfield staining). Brown dots correspond to proximity/interaction between MUC1 and β-catenin. Arrows indicate the PLA signals in HPAF-II wt tumors. IP, immunoprecipitation; IB, immunoblotting; CD, cluster of differentiation; wt, wild-type; MUC1, mucin 1; MUC1-CD, mucin 1 cytoplasmic domain; PLA, proximity ligation assay.
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f3-ol-0-0-4888: Evaluation of MUC1/β-catenin interaction in HPAF-II cells and xenografts. (A) β-catenin expression and its interaction with MUC1-CD in HPAF-II wt, HPAF-II CD133low and HPAF-II CD133+ cells was evaluated by immunoprecipitation and western blot analysis. β-actin was used as a loading control. (B) In situ PLA in tumor xenografts was used to evaluate the interaction between MUC1 and β-catenin; magnification, (a) ×400; (b) ×650 (Duolink in situ Detection Reagents Brightfield staining). Brown dots correspond to proximity/interaction between MUC1 and β-catenin. Arrows indicate the PLA signals in HPAF-II wt tumors. IP, immunoprecipitation; IB, immunoblotting; CD, cluster of differentiation; wt, wild-type; MUC1, mucin 1; MUC1-CD, mucin 1 cytoplasmic domain; PLA, proximity ligation assay.

Mentions: MUC1-CD contains docking sites for β-catenin, and the interactions between MUC1 and β-catenin are known to contribute to the malignant phenotype of tumor cells by modifying the expression of target genes in the Wnt signaling pathway (24,29). To assess if MUC1/β-catenin interaction was potentiated in CD133+ cells, MUC1 was immunoprecipitated from cell lysates of HPAF-II wt, HPAF-II CD133+ and HPAF-II CD133low cells, followed by β-catenin immunoblotting. An enrichment in MUC1/β-catenin interaction was observed in HPAF-II CD133+ cells. β-catenin expression levels were similar in all conditions (Fig. 3A).


Effect of MUC1/ β -catenin interaction on the tumorigenic capacity of pancreatic CD133 + cells
Evaluation of MUC1/β-catenin interaction in HPAF-II cells and xenografts. (A) β-catenin expression and its interaction with MUC1-CD in HPAF-II wt, HPAF-II CD133low and HPAF-II CD133+ cells was evaluated by immunoprecipitation and western blot analysis. β-actin was used as a loading control. (B) In situ PLA in tumor xenografts was used to evaluate the interaction between MUC1 and β-catenin; magnification, (a) ×400; (b) ×650 (Duolink in situ Detection Reagents Brightfield staining). Brown dots correspond to proximity/interaction between MUC1 and β-catenin. Arrows indicate the PLA signals in HPAF-II wt tumors. IP, immunoprecipitation; IB, immunoblotting; CD, cluster of differentiation; wt, wild-type; MUC1, mucin 1; MUC1-CD, mucin 1 cytoplasmic domain; PLA, proximity ligation assay.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4998183&req=5

f3-ol-0-0-4888: Evaluation of MUC1/β-catenin interaction in HPAF-II cells and xenografts. (A) β-catenin expression and its interaction with MUC1-CD in HPAF-II wt, HPAF-II CD133low and HPAF-II CD133+ cells was evaluated by immunoprecipitation and western blot analysis. β-actin was used as a loading control. (B) In situ PLA in tumor xenografts was used to evaluate the interaction between MUC1 and β-catenin; magnification, (a) ×400; (b) ×650 (Duolink in situ Detection Reagents Brightfield staining). Brown dots correspond to proximity/interaction between MUC1 and β-catenin. Arrows indicate the PLA signals in HPAF-II wt tumors. IP, immunoprecipitation; IB, immunoblotting; CD, cluster of differentiation; wt, wild-type; MUC1, mucin 1; MUC1-CD, mucin 1 cytoplasmic domain; PLA, proximity ligation assay.
Mentions: MUC1-CD contains docking sites for β-catenin, and the interactions between MUC1 and β-catenin are known to contribute to the malignant phenotype of tumor cells by modifying the expression of target genes in the Wnt signaling pathway (24,29). To assess if MUC1/β-catenin interaction was potentiated in CD133+ cells, MUC1 was immunoprecipitated from cell lysates of HPAF-II wt, HPAF-II CD133+ and HPAF-II CD133low cells, followed by β-catenin immunoblotting. An enrichment in MUC1/β-catenin interaction was observed in HPAF-II CD133+ cells. β-catenin expression levels were similar in all conditions (Fig. 3A).

View Article: PubMed Central - PubMed

ABSTRACT

Despite the fact that the biological function of cluster of differentiation (CD)133 remains unclear, this glycoprotein is currently used in the identification and isolation of tumor-initiating cells from certain malignant tumors, including pancreatic cancer. In the present study, the involvement of mucin 1 (MUC1) in the signaling pathways of a highly tumorigenic CD133+ cellular subpopulation sorted from the pancreatic cancer cell line HPAF-II was evaluated. The expression of MUC1-cytoplasmic domain (MUC1-CD) and oncogenic signaling transducers (epidermal growth factor receptor, protein kinase C delta, glycogen synthase kinase 3 beta and growth factor receptor-bound protein 2), as well as the association between MUC1 and β-catenin, were characterized in HPAF-II CD133+ and CD133low cell subpopulations and in tumor xenografts generated from these cells. Compared with HPAF CD133low cells, HPAF-II CD133+ cancer cells exhibited increased tumorigenic potential in immunocompromised mice, which was associated with overexpression of MUC1 and with the accordingly altered expression profile of MUC1-associated signaling partners. Additionally, MUC1-CD/β-catenin interactions were increased both in the HPAF-II CD133+ cell subpopulation and derived tumor xenografts compared with HPAF CD133low cells. These results suggest that, in comparison with HPAF CD133low cells, CD133+ cells exhibit higher expression of MUC1, which contributes to their tumorigenic phenotype through increased interaction between MUC1-CD and β-catenin, which in turn modulates oncogenic signaling cascades.

No MeSH data available.


Related in: MedlinePlus