Limits...
Upregulated HSP27 in human breast cancer cells reduces Herceptin susceptibility by increasing Her2 protein stability.

Kang SH, Kang KW, Kim KH, Kwon B, Kim SK, Lee HY, Kong SY, Lee ES, Jang SG, Yoo BC - BMC Cancer (2008)

Bottom Line: However, Her2 expression was reduced by a greater amount in SK-BR-3 parent cells than in SK-BR-3 HR cells.Interestingly, co-immunoprecipitation analysis showed that HSP27 can bind to Her2.In the absence of Herceptin, HSP27 expression is suppressed and Her2 expression is reduced, indicating that downregulation of Her2 by Herceptin can be obstructed by the formation of a Her2-HSP27 complex.

View Article: PubMed Central - HTML - PubMed

Affiliation: Research Institute and Hospital, National Cancer Center, Republic of Korea. neology7@ncc.re.kr

ABSTRACT

Background: Elucidating the molecular mechanisms by which tumors become resistant to Herceptin is critical for the treatment of Her2-overexpressed metastatic breast cancer.

Methods: To further understand Herceptin resistance mechanisms at the molecular level, we used comparative proteome approaches to analyze two human breast cancer cell lines; Her2-positive SK-BR-3 cells and its Herceptin-resistant SK-BR-3 (SK-BR-3 HR) cells.

Results: Heat-shock protein 27 (HSP27) expression was shown to be upregulated in SK-BR-3 HR cells. Suppression of HSP27 by specific siRNA transfection increased the susceptibility of SK-BR-3 HR cells to Herceptin. In the presence of Herceptin, Her2 was downregulated in both cell lines. However, Her2 expression was reduced by a greater amount in SK-BR-3 parent cells than in SK-BR-3 HR cells. Interestingly, co-immunoprecipitation analysis showed that HSP27 can bind to Her2. In the absence of Herceptin, HSP27 expression is suppressed and Her2 expression is reduced, indicating that downregulation of Her2 by Herceptin can be obstructed by the formation of a Her2-HSP27 complex.

Conclusion: Our present study demonstrates that upregulated HSP27 in human breast cancer cells can reduce Herceptin susceptibility by increasing Her2 protein stability.

Show MeSH

Related in: MedlinePlus

Identification of HSP27 overexpressed in SK-BR-3 HR. (a) Typical pattern of two-dimensional (2-DE) gel electrophoresis analysis of SK-BR-3 and SK-BR-3 HR cells. (b) Identification of HSP27 by MALDI-MS analysis. The protein spot indicated in the enlarged image in Figure 2A was in-gel-digested by trypsin and subjected to MALDI-MS analysis. The protein was identified as human HSP27. (c) Western-blot analysis to confirm overexpressed HSP27 in SK-BR-3 HR cells. (d) Subcellular levels of HSP27 and Her2 in seven individual human breast cancer cell lines.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2567332&req=5

Figure 2: Identification of HSP27 overexpressed in SK-BR-3 HR. (a) Typical pattern of two-dimensional (2-DE) gel electrophoresis analysis of SK-BR-3 and SK-BR-3 HR cells. (b) Identification of HSP27 by MALDI-MS analysis. The protein spot indicated in the enlarged image in Figure 2A was in-gel-digested by trypsin and subjected to MALDI-MS analysis. The protein was identified as human HSP27. (c) Western-blot analysis to confirm overexpressed HSP27 in SK-BR-3 HR cells. (d) Subcellular levels of HSP27 and Her2 in seven individual human breast cancer cell lines.

Mentions: To verify the differential protein expression between the SK-BR-3 and SK-BR-3 HR cell lines, total proteins were isolated from SK-BR-3 and SK-BR-3 HR cells and subjected to 2-DE. A strongly stained protein spot from SK-BR-3 HR cells (enlarged partial 2-DE gels on Fig. 2a) was in-gel digested for MALDI-MS analysis, and shown to be human HSP27 (Fig. 2b). Increased levels of HSP27 in SK-BR-3 HR cells were confirmed by Western-blot analysis (Fig. 2c). However, there were no differences in Her2 expression between the two cell lines (Fig. 2c, d). The subcellular levels of HSP27 and Her2 were investigated in seven human breast cancer cell lines, including SK-BR-3 and SK-BR-3 HR (Fig. 2d). Most HSP27 was localized in the cytoplasm of the breast cancer cell lines tested. However, there was no correlation between Herceptin susceptibility in breast cancer cell lines and HSP27 expression (Fig. 2d). HSP27 expression in JIMT-1, which is a cell line that has previously been reported to be Herceptin resistant, was lower than in SK-BR-3 HR (Fig. 2d).


Upregulated HSP27 in human breast cancer cells reduces Herceptin susceptibility by increasing Her2 protein stability.

Kang SH, Kang KW, Kim KH, Kwon B, Kim SK, Lee HY, Kong SY, Lee ES, Jang SG, Yoo BC - BMC Cancer (2008)

Identification of HSP27 overexpressed in SK-BR-3 HR. (a) Typical pattern of two-dimensional (2-DE) gel electrophoresis analysis of SK-BR-3 and SK-BR-3 HR cells. (b) Identification of HSP27 by MALDI-MS analysis. The protein spot indicated in the enlarged image in Figure 2A was in-gel-digested by trypsin and subjected to MALDI-MS analysis. The protein was identified as human HSP27. (c) Western-blot analysis to confirm overexpressed HSP27 in SK-BR-3 HR cells. (d) Subcellular levels of HSP27 and Her2 in seven individual human breast cancer cell lines.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2567332&req=5

Figure 2: Identification of HSP27 overexpressed in SK-BR-3 HR. (a) Typical pattern of two-dimensional (2-DE) gel electrophoresis analysis of SK-BR-3 and SK-BR-3 HR cells. (b) Identification of HSP27 by MALDI-MS analysis. The protein spot indicated in the enlarged image in Figure 2A was in-gel-digested by trypsin and subjected to MALDI-MS analysis. The protein was identified as human HSP27. (c) Western-blot analysis to confirm overexpressed HSP27 in SK-BR-3 HR cells. (d) Subcellular levels of HSP27 and Her2 in seven individual human breast cancer cell lines.
Mentions: To verify the differential protein expression between the SK-BR-3 and SK-BR-3 HR cell lines, total proteins were isolated from SK-BR-3 and SK-BR-3 HR cells and subjected to 2-DE. A strongly stained protein spot from SK-BR-3 HR cells (enlarged partial 2-DE gels on Fig. 2a) was in-gel digested for MALDI-MS analysis, and shown to be human HSP27 (Fig. 2b). Increased levels of HSP27 in SK-BR-3 HR cells were confirmed by Western-blot analysis (Fig. 2c). However, there were no differences in Her2 expression between the two cell lines (Fig. 2c, d). The subcellular levels of HSP27 and Her2 were investigated in seven human breast cancer cell lines, including SK-BR-3 and SK-BR-3 HR (Fig. 2d). Most HSP27 was localized in the cytoplasm of the breast cancer cell lines tested. However, there was no correlation between Herceptin susceptibility in breast cancer cell lines and HSP27 expression (Fig. 2d). HSP27 expression in JIMT-1, which is a cell line that has previously been reported to be Herceptin resistant, was lower than in SK-BR-3 HR (Fig. 2d).

Bottom Line: However, Her2 expression was reduced by a greater amount in SK-BR-3 parent cells than in SK-BR-3 HR cells.Interestingly, co-immunoprecipitation analysis showed that HSP27 can bind to Her2.In the absence of Herceptin, HSP27 expression is suppressed and Her2 expression is reduced, indicating that downregulation of Her2 by Herceptin can be obstructed by the formation of a Her2-HSP27 complex.

View Article: PubMed Central - HTML - PubMed

Affiliation: Research Institute and Hospital, National Cancer Center, Republic of Korea. neology7@ncc.re.kr

ABSTRACT

Background: Elucidating the molecular mechanisms by which tumors become resistant to Herceptin is critical for the treatment of Her2-overexpressed metastatic breast cancer.

Methods: To further understand Herceptin resistance mechanisms at the molecular level, we used comparative proteome approaches to analyze two human breast cancer cell lines; Her2-positive SK-BR-3 cells and its Herceptin-resistant SK-BR-3 (SK-BR-3 HR) cells.

Results: Heat-shock protein 27 (HSP27) expression was shown to be upregulated in SK-BR-3 HR cells. Suppression of HSP27 by specific siRNA transfection increased the susceptibility of SK-BR-3 HR cells to Herceptin. In the presence of Herceptin, Her2 was downregulated in both cell lines. However, Her2 expression was reduced by a greater amount in SK-BR-3 parent cells than in SK-BR-3 HR cells. Interestingly, co-immunoprecipitation analysis showed that HSP27 can bind to Her2. In the absence of Herceptin, HSP27 expression is suppressed and Her2 expression is reduced, indicating that downregulation of Her2 by Herceptin can be obstructed by the formation of a Her2-HSP27 complex.

Conclusion: Our present study demonstrates that upregulated HSP27 in human breast cancer cells can reduce Herceptin susceptibility by increasing Her2 protein stability.

Show MeSH
Related in: MedlinePlus