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
Overview
Affiliations
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.
Yang S, Liu C, Hong C, Huang Z, Wang H, Wei L Dis Markers. 2021; 2021:5592693.
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Lin D, Lin H, Xiong X Inflammation. 2014; 37(6):1912-8.
PMID: 24830325 DOI: 10.1007/s10753-014-9923-0.
Dudas J, Schartinger V, Romani A, Schweigl G, Kordsmeyer K, Marta P Tumour Biol. 2014; 35(8):7807-19.
PMID: 24817012 PMC: 4158184. DOI: 10.1007/s13277-014-2001-2.