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Co-overexpression of Bag-1 and heat shock protein 70 in human epidermal squamous cell carcinoma: Bag-1-mediated resistance to 5-fluorouracil-induced apoptosis.

Wood J, Pring M, Eveson JW, Price N, Proby CM, Hague A - Br. J. Cancer (2011)

Bottom Line: Most tumours showed reduced nuclear Bag-1 staining, but a subset exhibited strong Bag-1 staining, with cytoplasmic Bag-1 staining intensity correlating with cytoplasmic Hsp70 staining intensity (r(s)=0.462; P<0.001) and less differentiation (P<0.001).Bag-1 knockdown resulted in markedly reduced SCC-13 cell yield, increased spontaneous apoptosis and enhanced sensitivity to 5-FU-induced apoptosis.Apoptosis induced by 5-FU in the Bag-1-knockdown cells was significantly greater than the additive apoptotic effect of 5-FU or Bag-1 knockdown alone.

View Article: PubMed Central - PubMed

Affiliation: School of Oral and Dental Science, University of Bristol, Lower Maudlin Street, Bristol BS1 2LY, UK.

ABSTRACT

Background: The aim was to determine whether Bcl-2-associated athanogene-1 (Bag-1) and/or its binding protein heat shock protein-70 (Hsp70) exhibit deregulated expression in epidermal squamous cell carcinoma (SCC) and whether Bag-1 confers apoptosis resistance.

Method: Immunohistochemistry for Bag-1 and Hsp70 was performed on 60 epidermal SCC and 10 normal skin samples. The epidermal SCC cell line SCC-13 was treated with 5-fluorouracil (5-FU) after Bag-1 knockdown to determine whether high Bag-1 levels contribute to growth and/or apoptosis resistance.

Results: Normal epithelium expressed primarily nuclear Bag-1. Most tumours showed reduced nuclear Bag-1 staining, but a subset exhibited strong Bag-1 staining, with cytoplasmic Bag-1 staining intensity correlating with cytoplasmic Hsp70 staining intensity (r(s)=0.462; P<0.001) and less differentiation (P<0.001). Bag-1 knockdown resulted in markedly reduced SCC-13 cell yield, increased spontaneous apoptosis and enhanced sensitivity to 5-FU-induced apoptosis. Apoptosis induced by 5-FU in the Bag-1-knockdown cells was significantly greater than the additive apoptotic effect of 5-FU or Bag-1 knockdown alone.

Conclusions: Overexpression of Bag-1 and Hsp70 in poorly differentiated SCC may confer both enhanced tumour cell growth and apoptosis resistance. Bag-1 may contribute to the resistance of more advanced epidermal SCC to chemotherapy.

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Correlation between Bag-1 and Hsp70 expression. (A and B) Epidermal SCC negative for Hsp70 staining. (C and D) Corresponding areas of the same tumour stained for Bag-1 showing weak cytoplasmic Bag-1 expression and moderate nuclear staining. (E and F) Epidermal SCC showing a moderate level of cytoplasmic and nuclear Hsp70 staining. (G and H) Corresponding areas of the same tumour shown in E and F stained for Bag-1, showing strong cytoplasmic and nuclear Bag-1 staining. Images E and G were photographed using a × 4 objective (scale bar shown in E), images A and C were photographed using a × 10 objective (scale bar shown in A) and images B, D, F and H using a × 40 objective (scale bar shown in B). (I) Relationship between Hsp70 positivity and intensity of Bag-1 staining in SCCs. Statistical analysis was performed using a Mann–Whitney test. 0=undetectable Bag-1 staining; +=weak; ++=moderate; +++=strong cytoplasmic Bag-1 staining scores.
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fig5: Correlation between Bag-1 and Hsp70 expression. (A and B) Epidermal SCC negative for Hsp70 staining. (C and D) Corresponding areas of the same tumour stained for Bag-1 showing weak cytoplasmic Bag-1 expression and moderate nuclear staining. (E and F) Epidermal SCC showing a moderate level of cytoplasmic and nuclear Hsp70 staining. (G and H) Corresponding areas of the same tumour shown in E and F stained for Bag-1, showing strong cytoplasmic and nuclear Bag-1 staining. Images E and G were photographed using a × 4 objective (scale bar shown in E), images A and C were photographed using a × 10 objective (scale bar shown in A) and images B, D, F and H using a × 40 objective (scale bar shown in B). (I) Relationship between Hsp70 positivity and intensity of Bag-1 staining in SCCs. Statistical analysis was performed using a Mann–Whitney test. 0=undetectable Bag-1 staining; +=weak; ++=moderate; +++=strong cytoplasmic Bag-1 staining scores.

Mentions: In serial sections, areas of tumour positive for cytoplasmic Hsp70 tended to exhibit strong cytoplasmic Bag-1 staining (Figure 5) and there was a clear association between intensity of Hsp70 and Bag-1 staining, with a correlation between cytoplasmic Bag-1 and Hsp70 staining intensity scores (P<0.001; correlation coefficient=0.462). There was also a weak correlation between the percentage of cells that stained positively for Hsp70 in the tumours and the percentage that were positive for Bag-1 (P=0.027; correlation coefficient=0.286). However, there was no association between nuclear staining intensities for these two proteins (P=0.067).


Co-overexpression of Bag-1 and heat shock protein 70 in human epidermal squamous cell carcinoma: Bag-1-mediated resistance to 5-fluorouracil-induced apoptosis.

Wood J, Pring M, Eveson JW, Price N, Proby CM, Hague A - Br. J. Cancer (2011)

Correlation between Bag-1 and Hsp70 expression. (A and B) Epidermal SCC negative for Hsp70 staining. (C and D) Corresponding areas of the same tumour stained for Bag-1 showing weak cytoplasmic Bag-1 expression and moderate nuclear staining. (E and F) Epidermal SCC showing a moderate level of cytoplasmic and nuclear Hsp70 staining. (G and H) Corresponding areas of the same tumour shown in E and F stained for Bag-1, showing strong cytoplasmic and nuclear Bag-1 staining. Images E and G were photographed using a × 4 objective (scale bar shown in E), images A and C were photographed using a × 10 objective (scale bar shown in A) and images B, D, F and H using a × 40 objective (scale bar shown in B). (I) Relationship between Hsp70 positivity and intensity of Bag-1 staining in SCCs. Statistical analysis was performed using a Mann–Whitney test. 0=undetectable Bag-1 staining; +=weak; ++=moderate; +++=strong cytoplasmic Bag-1 staining scores.
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fig5: Correlation between Bag-1 and Hsp70 expression. (A and B) Epidermal SCC negative for Hsp70 staining. (C and D) Corresponding areas of the same tumour stained for Bag-1 showing weak cytoplasmic Bag-1 expression and moderate nuclear staining. (E and F) Epidermal SCC showing a moderate level of cytoplasmic and nuclear Hsp70 staining. (G and H) Corresponding areas of the same tumour shown in E and F stained for Bag-1, showing strong cytoplasmic and nuclear Bag-1 staining. Images E and G were photographed using a × 4 objective (scale bar shown in E), images A and C were photographed using a × 10 objective (scale bar shown in A) and images B, D, F and H using a × 40 objective (scale bar shown in B). (I) Relationship between Hsp70 positivity and intensity of Bag-1 staining in SCCs. Statistical analysis was performed using a Mann–Whitney test. 0=undetectable Bag-1 staining; +=weak; ++=moderate; +++=strong cytoplasmic Bag-1 staining scores.
Mentions: In serial sections, areas of tumour positive for cytoplasmic Hsp70 tended to exhibit strong cytoplasmic Bag-1 staining (Figure 5) and there was a clear association between intensity of Hsp70 and Bag-1 staining, with a correlation between cytoplasmic Bag-1 and Hsp70 staining intensity scores (P<0.001; correlation coefficient=0.462). There was also a weak correlation between the percentage of cells that stained positively for Hsp70 in the tumours and the percentage that were positive for Bag-1 (P=0.027; correlation coefficient=0.286). However, there was no association between nuclear staining intensities for these two proteins (P=0.067).

Bottom Line: Most tumours showed reduced nuclear Bag-1 staining, but a subset exhibited strong Bag-1 staining, with cytoplasmic Bag-1 staining intensity correlating with cytoplasmic Hsp70 staining intensity (r(s)=0.462; P<0.001) and less differentiation (P<0.001).Bag-1 knockdown resulted in markedly reduced SCC-13 cell yield, increased spontaneous apoptosis and enhanced sensitivity to 5-FU-induced apoptosis.Apoptosis induced by 5-FU in the Bag-1-knockdown cells was significantly greater than the additive apoptotic effect of 5-FU or Bag-1 knockdown alone.

View Article: PubMed Central - PubMed

Affiliation: School of Oral and Dental Science, University of Bristol, Lower Maudlin Street, Bristol BS1 2LY, UK.

ABSTRACT

Background: The aim was to determine whether Bcl-2-associated athanogene-1 (Bag-1) and/or its binding protein heat shock protein-70 (Hsp70) exhibit deregulated expression in epidermal squamous cell carcinoma (SCC) and whether Bag-1 confers apoptosis resistance.

Method: Immunohistochemistry for Bag-1 and Hsp70 was performed on 60 epidermal SCC and 10 normal skin samples. The epidermal SCC cell line SCC-13 was treated with 5-fluorouracil (5-FU) after Bag-1 knockdown to determine whether high Bag-1 levels contribute to growth and/or apoptosis resistance.

Results: Normal epithelium expressed primarily nuclear Bag-1. Most tumours showed reduced nuclear Bag-1 staining, but a subset exhibited strong Bag-1 staining, with cytoplasmic Bag-1 staining intensity correlating with cytoplasmic Hsp70 staining intensity (r(s)=0.462; P<0.001) and less differentiation (P<0.001). Bag-1 knockdown resulted in markedly reduced SCC-13 cell yield, increased spontaneous apoptosis and enhanced sensitivity to 5-FU-induced apoptosis. Apoptosis induced by 5-FU in the Bag-1-knockdown cells was significantly greater than the additive apoptotic effect of 5-FU or Bag-1 knockdown alone.

Conclusions: Overexpression of Bag-1 and Hsp70 in poorly differentiated SCC may confer both enhanced tumour cell growth and apoptosis resistance. Bag-1 may contribute to the resistance of more advanced epidermal SCC to chemotherapy.

Show MeSH
Related in: MedlinePlus