HspBP1 levels are elevated in breast tumor tissue and inversely related to tumor aggressiveness |
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Authors: | Ana Paula Souza Caroline Albuquerque Carolina Torronteguy Antonio Frasson Fabio Maito Luciana Pereira Vinícius Duval da Silva Felipe Zerwes Deborah Raynes Vince Guerriero Cristina Bonorino |
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Institution: | Faculdade de Biociências e Instituto de Pesquisas Biomédicas, PUCRS, Av. Ipiranga, 6690 2o andar, 90610-000, Porto Alegre, RS, Brazil. |
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Abstract: | HspBP1 is a co-chaperone that binds to and regulates the chaperone Hsp70 (Hsp70 is used to refer to HSPA1A and HSPA1B). Hsp70
is known to be elevated in breast tumor tissue, therefore the purpose of these studies was to quantify the expression of HspBP1
in primary breast tumors and in serum of these patients with a follow-up analysis after 6 to 7 years. Levels of HspBP1, Hsp70,
and anti-HspBP1 antibodies in sera of breast cancer patients and healthy individuals were measured by enzyme-linked immunosorbent
assay. Expression of HspBP1 was quantified from biopsies of tumor and normal breast tissue by Western blot analysis. The data
obtained were analyzed for association with tumor aggressiveness markers and with patient outcome. The levels of HspBP1 and
Hsp70 were significantly higher in sera of patients compared to sera of healthy individuals. HspBP1 antibodies did not differ
significantly between groups. HspBP1 levels were significantly higher in tumor (14.46 ng/μg protein, n = 51) compared to normal adjacent tissue (3.17 ng/μg protein, n = 41, p < 0.001). Expression of HspBP1 was significantly lower in patients with lymph node metastasis and positive for estrogen receptors.
HspBP1 levels were also significantly lower in patients with a higher incidence of metastasis and death following a 6 to 7-year
follow-up. The HspBP1/Hsp70 molar ratio was not associated with the prognostic markers analyzed. Our results indicate that
low HspBP1 expression could be a candidate tumor aggressiveness marker.
This work was supported by FAPERGS, CNPq, and the National Institute of General Medical Sciences grant number GM072628-02
(V.G.)
The expression of HspBP1 (an Hsp70 co-chaperone) was analyzed in tumor samples and sera from breast cancer patients. HspBP1
is over expressed in these tumors and a seven year follow-up analysis found an association with a poor prognosis. Chaperones
have been shown to play important roles in tumor biology and immunology; therefore, we believe the data in this study will
serve as a basis for the formulation of a new hypothesis on chaperone-co-chaperone interactions and their role in tumor growth. |
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Keywords: | Breast cancer Co-chaperone HspBP1 Hsp70 Prognostic markers |
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