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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.

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Related in: MedlinePlus

Establishment of human breast cancer cell line SK-BR-3 with Herceptin resistance. (a) Microscopy images showing increased cell proliferation of the SK-BR-3 derivative cell line SK-BR-3 HR in the presence of Herceptin. (b) Differential proliferation rate of SK-BR-3 HR in the presence of Herceptin. Data are means ± standard deviations of three independent experiments. (c) Genotyping of SK-BR-3 and SK-BR-3 HR, showing the two cell lines have the same genetic identity.
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Figure 1: Establishment of human breast cancer cell line SK-BR-3 with Herceptin resistance. (a) Microscopy images showing increased cell proliferation of the SK-BR-3 derivative cell line SK-BR-3 HR in the presence of Herceptin. (b) Differential proliferation rate of SK-BR-3 HR in the presence of Herceptin. Data are means ± standard deviations of three independent experiments. (c) Genotyping of SK-BR-3 and SK-BR-3 HR, showing the two cell lines have the same genetic identity.

Mentions: The Human breast cancer cell line SK-BR-3 was cultured according to the ATCC instructions, and the derivative cell line from SK-BR-3 with reduced Herceptin susceptibility was generated spontaneously by increasing generation-to-generation passage. Microscopy images in Fig. 1a show increased proliferation of the Herceptin-resistant SK-BR-3 derivative cell line (SK-BR-3 HR) in the presence of Herceptin. Increased proliferation of SK-BR-3 HR cells in the presence of Herceptin was confirmed by the MTT time-course assay (Fig. 1b). However, these two cell lines, parent SK-BR-3 and the Herceptin-resistant SK-BR-3 HR, are genetically identical (Fig. 1c).


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)

Establishment of human breast cancer cell line SK-BR-3 with Herceptin resistance. (a) Microscopy images showing increased cell proliferation of the SK-BR-3 derivative cell line SK-BR-3 HR in the presence of Herceptin. (b) Differential proliferation rate of SK-BR-3 HR in the presence of Herceptin. Data are means ± standard deviations of three independent experiments. (c) Genotyping of SK-BR-3 and SK-BR-3 HR, showing the two cell lines have the same genetic identity.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Establishment of human breast cancer cell line SK-BR-3 with Herceptin resistance. (a) Microscopy images showing increased cell proliferation of the SK-BR-3 derivative cell line SK-BR-3 HR in the presence of Herceptin. (b) Differential proliferation rate of SK-BR-3 HR in the presence of Herceptin. Data are means ± standard deviations of three independent experiments. (c) Genotyping of SK-BR-3 and SK-BR-3 HR, showing the two cell lines have the same genetic identity.
Mentions: The Human breast cancer cell line SK-BR-3 was cultured according to the ATCC instructions, and the derivative cell line from SK-BR-3 with reduced Herceptin susceptibility was generated spontaneously by increasing generation-to-generation passage. Microscopy images in Fig. 1a show increased proliferation of the Herceptin-resistant SK-BR-3 derivative cell line (SK-BR-3 HR) in the presence of Herceptin. Increased proliferation of SK-BR-3 HR cells in the presence of Herceptin was confirmed by the MTT time-course assay (Fig. 1b). However, these two cell lines, parent SK-BR-3 and the Herceptin-resistant SK-BR-3 HR, are genetically identical (Fig. 1c).

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