[Show abstract][Hide abstract] ABSTRACT: In a recent study, we have shown that in mammary tumors from mice lacking the Cav-1 gene, there are alterations in specific heat shock proteins as well as in tumor development. With this in mind, we have now investigated other proteins in the same mammary mouse tumor model (Her-2/neu expressing mammary tumors from Cav-1 wild type and Cav-1 null mice), to further comprehend the complex tumor-stroma mechanisms involved in regulating stress responses during tumor development. In this tumor model the cancer cells always lacked of Cav-1, so the KO influenced the Cav-1 in the stroma. By immunohistochemistry, we have found a striking co-expression of β-catenin and Her-2/neu in the tumor cells. The absence of Cav-1 in the tumor stroma had no effect on expression or localization of β-catenin and Her-2/neu. Both proteins appeared co-localized at the cell surface during tumor development and progression. Since Her-2/neu activation induces MTA1, we next evaluated MTA1 in the mouse tumors. Although this protein was found in numerous nuclei, the absence of Cav-1 did not alter its expression level. In contrast, significantly more PTEN protein was noted in the tumors lacking Cav-1 in the stroma, with the protein localized mainly in the nuclei. P-Akt levels were relatively low in tumors from both Cav-1 WT and Cav-1 KO mice. There was also an increase in nuclear NHERF1 expression levels in the tumors arising from Cav-1 KO mice. The data obtained in the MMTV-neu model are consistent with a role for Cav-1 in adjacent breast cancer stromal cells in modulating the expression and localization of important proteins implicated in tumor cell behavior.
Cell Stress and Chaperones 02/2013; · 2.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hsp27 (HSPB1) is usually overexpressed in breast cancers affecting the disease outcome and the sensitivity of tumors to chemotherapy and radiotherapy. Hsp27 interacts with other proteins such as β-catenin, histone deacetylase HDAC6, transcription factor STAT2 and procaspase-3. Phosphatase and tensin homologue (PTEN) is a tumor suppressor gene that is deleted in many human tumors. The PI3K/Akt signaling pathway is negatively regulated by PTEN. Hsp27 is described as a key component of the Akt signaling cascade: Akt, BAD, Forkhead transcription factors, Hsp27, mitogen-activated protein kinase kinase-3 and -6. Here, we have examined whether the downregulation of Hsp27 by siHsp27 affects the PTEN levels in the MCF-7 human breast cancer cell line. PTEN was detected with two different antibodies using western blots and immunocytochemistry. p-Akt was also evaluated by western blot. In addition, Hsp27 and PTEN were immunoprecipitated to know whether these proteins interact. Intracellular colocalization studies were carried out by confocal microscopy. A significant reduction in the Hsp27 levels was noted in the siHsp27 transfected cells. These Hsp27 downregulated cells showed a significant increased expression of PTEN. The MW 76 and 55 kDa PTEN forms were upregulated as revealed by two different antibodies. The phosphatase activity of PTEN seems to be active because p-Akt levels were reduced. Hsp27 immunoprecipitation was bringing PTEN and vice versa, these two proteins seem to interact at cytoplasmic level by FRET. Downregulation of Hsp27 stabilized PTEN protein levels. Chaperone-assisted E3 ligase C terminus of Hsc70-interacting protein (CHIP) levels were not significantly influenced by Hsp27 downregulation. In conclusion, we report a novel function of Hsp27 modulating the PTEN levels in human breast cancer cells suggesting an interaction between these two molecules.
Cell Stress and Chaperones 08/2012; · 2.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In oligodendrogliomas, 1p loss of heterozygosity (LOH) is a predictor of good prognosis and treatment response. In contrast, in uveal melanomas, LOH of chromosome 3 has been linked to poor prognosis and downregulation of Hsp27. In the present study, we have analyzed the expression of heat-shock proteins (Hsps) to characterize subtypes of gliomas and their histopathologic features and to correlate with other molecular markers including LOH of 1p. Biopsies from patients with primary gliomas (n = 65) were analyzed by immunohistochemistry, chromogenic in situ hybridization and fluorescent in situ hybridization and methylation-specific PCR (MSP). Elevated Hsp27 and total Hsp70 expression levels were associated with high-grade astrocytomas (p = 0.0001 and p = 0.01, respectively). In grade III oligodendrogliomas, the Hsp27 levels were significantly higher (p = 0.03). Low O6-methylguanine-DNA methyltransferase (MGMT) expression was associated with grade II astrocytomas. Elevated β-catenin expression was associated with grade III/IV astrocytomas (p = 0.003); p53 (+) tumors were more frequently found in grade III/IV astrocytomas (p = 0,001). LOH on 1p was associated with oligodendroglial tumours. In addition, a higher Hsp27 expression correlated with LOH of 1p (p = 0.017); this was also tested in two glioma cell lines. MSP was successful in only six samples. No significant correlations were found for the other markers. In conclusion, in oligodendroglial tumors, Hsp27 appeared as a surrogate marker of LOH of 1p which could also help to predict the disease prognosis. In gliomas, p53, Hsp27, Hsp70, MGMT, and β-catenin correlated with histopathological characteristics, suggesting that these markers could predict the disease outcome and the response to treatments.
Cell Stress and Chaperones 07/2012; 17(6):779-90. · 2.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The importance of HSPs themselves in antigen presentation and cross-presentation remains controversial. Most studies agree that as part of their molecular chaperone function, HSPs can bind and present tumor associated antigens to professional antigen presenting cells through MHC class I and class II molecules, leading to the activation of anti-tumor CD8+ and CD4+ T cells. The regulation of the innate and adaptive immune responses by HSPs is still a matter of intense research. HSPs are seen as important anticancer vaccine adjuvants. They are used through different delivery systems: HSPs/antibodies, peptide/protein-HSP complexes, tumor antigen/HSP gene fusion, viral peptides/HSP complexes or gene fusion, viral proteins/bacterial HSP fusion. In preclinical models different administration routes, subcutaneous, intradermal, intramuscular or even peroral (under special conditions) can be used, and the animal toxicities are non-significant. The HSP-based vaccines can induce specific and non-specific cellular immune responses all of which are important to induce tumor rejection. In addition, the antibodies generated after vaccination are emerging as important protagonist in the antitumoral response. This response is significantly enhanced when the suppressive tumor microenvironment and the immune suppressing effector cells are blocked. Several clinical studies have been carried out and are ongoing, immunizing cancer patients with autologous tumor derived HSP-peptide complexes (HSPPCs). The most promising results have been observed in patients with melanoma and renal clear cell cancer without advanced disease. There are clinical trials with HSP-based anticancer vaccines other than with HSPPCs (including patients with non-Hodgkin lymphoma, high-grade transitional cell carcinoma of the bladder, high-grade cervical dysplasia, etc).
Current Molecular Medicine 07/2012; · 4.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Heat shock proteins (Hsp) are molecular chaperones with the capability to interact with a wide range of other proteins and are thus often found coupled with other heat shock and non-heat shock proteins. This can be an advantage to study specific interactions between a chaperone and other proteins and to generate an antitumoral immune response. In this chapter, we present two protocols to isolate Hsp. One involves column chromatography with hydroxyapatite and the other employs immunoprecipitation with antibodies coupled to magnetic beads. In both cases, we specifically want to isolate Hsp coupled with other proteins and use the Hsp complexes as intermediaries to present the coupled peptides/proteins to the immune system, or to explore the associations of a particular Hsp with other proteins.