Comprehensive transcriptomic analysis of heat shock proteins in the molecular subtypes of human breast cancer.

BACKGROUND: Heat Shock Proteins (HSPs), a family of genes with key roles in proteostasis, have been extensively associated with cancer behaviour. However, the HSP family is quite large and many of its members have not been investigated in breast cancer (BRCA), particularly in relation with the current molecular BRCA classification. In this work, we performed a comprehensive transcriptomic study of the HSP gene family in BRCA patients from both The Cancer Genome Atlas (TCGA) and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) cohorts discriminating the BRCA intrinsic molecular subtypes. METHODS: We examined gene expression levels of 1097 BRCA tissue samples retrieved from TCGA and 1981 samples of METABRIC, focusing mainly on the HSP family (95 genes). Data were stratified according to the PAM50 gene expression (Luminal A, Luminal B, HER2, Basal, and Normal-like). Transcriptomic analyses include several statistical approaches: differential gene expression, hierarchical clustering and survival analysis. RESULTS: Of the 20,531 analysed genes we found that in BRCA almost 30% presented deregulated expression (19% upregulated and 10% downregulated), while of the HSP family 25% appeared deregulated (14% upregulated and 11% downregulated) (|fold change| > 2 comparing BRCA with normal breast tissues). The study revealed the existence of shared HSP genes deregulated in all subtypes of BRCA while other HSPs were deregulated in specific subtypes. Many members of the Chaperonin subfamily were found upregulated while three members (BBS10, BBS12 and CCTB6) were found downregulated. HSPC subfamily had moderate increments of transcripts levels. Various genes of the HSP70 subfamily were upregulated; meanwhile, HSPA12A and HSPA12B appeared strongly downregulated. The strongest downregulation was observed in several HSPB members except for HSPB1. DNAJ members showed heterogeneous expression pattern. We found that 23 HSP genes correlated with overall survival and three HSP-based transcriptional profiles with impact on disease outcome were recognized. CONCLUSIONS: We identified shared and specific HSP genes deregulated in BRCA subtypes. This study allowed the recognition of HSP genes not previously associated with BRCA and/or any cancer type, and the identification of three clinically relevant clusters based on HSPs expression patterns with influence on overall survival.

Molecular markers of DNA damage and repair in cervical cancer patients treated with cisplatin neoadjuvant chemotherapy: an exploratory study.

Neoadjuvant (or induction) chemotherapy can be used for cervical cancer patients with locally advanced disease; this treatment is followed by radical surgery and/or radiation therapy. Cisplatin is considered to be the most active platinum agent drug for this cancer, with a response rate of 20%. In order to understand how the cisplatin treatment affects the stress response, in this work, we performed an exploratory study to analyze a number of stress proteins before and after cisplatin neoadjuvant chemotherapy. The study involved 14 patients; the pre- and post-chemotherapy paired biopsies were examined by hematoxylin and eosin staining and by immunohistochemistry. The proteins evaluated were p53, P16/INK4A, MSH2, nuclear protein transcriptional regulator 1 (NUPR1), and HSPB1 (total: HSPB1/t and phosphorylated: HSPB1/p). These proteins were selected because there is previous evidence of their relationship with drug resistance. The formation of platinum-DNA adducts was also studied. There was a great variation in the expression levels of the mentioned proteins in the pre-chemotherapy biopsies. After chemotherapy, p53 was not significantly affected by cisplatin, as well as P16/INK4A and MSH2 while nuclear NUPR1 content tended to decrease (p = 0.056). Cytoplasmic HSPB1/t expression levels decreased significantly following cisplatin therapy while nuclear HSPB1/t and HSPB1/p tended to increase. Since the most significant changes following chemotherapy appeared in the HSPB1 expression levels, the changes were confirmed by Western blot. The platinum-DNA adducts were observed in HeLa cell in apoptosis; however, in the tumor samples, the platinum-DNA adducts were observed in morphologically healthy tumor cells; these cells displayed nuclear HSPB1/p. Further mechanistic studies should be performed to reveal how HSPB1/p is related with drug resistance. When the correlations of the markers with the response to neoadjuvant chemotherapy were examined, only high pre-chemotherapy levels of cytoplasmic HSPB1/p correlated with a poor clinical and pathological response to neoadjuvant cisplatin chemotherapy (p = 0.056) suggesting that this marker could be useful opening its study in a larger number of cases.

HER2 and ß-catenin protein location: importance in the prognosis of breast cancer patients and their correlation when breast cancer cells suffer stressful situations.

In human breast cancer, ß-catenin localization has been related with disease prognosis. Since HER2-positive patients are an important subgroup, and that in breast cancer cells a direct interaction of ß-catenin/HER2 has been reported, in the present study we have explored whether ß-catenin location is related with the disease survival. The study was performed in a tumor bank from patients (n = 140) that did not receive specific anti-HER2 therapy. The proteins were detected by immunohistochemistry in serial sections, 47 (33.5%) patients were HER2-positive with a long follow-up. HER2-positive patients that displayed ß-catenin at the plasma membrane (completely surrounding the tumour cells) showed a significant better disease-free survival and overall survival than the patients showing the protein on other locations. Then we explored the dynamics of the co-expression of ß-catenin and HER2 in human MCF-7 and SKBR3 cells exposed to different stressful situations. In untreated conditions MCF-7 and SKBR3 cells showed very different ß-catenin localization. In MCF-7 cells, cadmium administration caused a striking change in ß-catenin localization driving it from plasma membrane to cytoplasmic and perinuclear areas and HER2 showed a similar localization patterns. The changes induced by cadmium were compared with heat shock, H2O2 and tamoxifen treatments. In conclusion, this study shows the dynamical associations of HER2 and ß-catenin and their changes in subcellular localizations driven by stressful situations. In addition, we report for the first time the correlation between plasma membrane associated ß-catenin in HER2-positive breast cancer and survival outcome, and the importance of the protein localization in breast cancer samples.

In MMTV-Her-2/neu transgenic mammary tumors the absence of caveolin-1-/- alters PTEN and NHERF1 but not ß-catenin expression.

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 ß-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 ß-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.

Hsp27 (HSPB1): a possible surrogate molecular marker for loss of heterozygosity (LOH) of chromosome 1p in oligodendrogliomas but not in astrocytomas.

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 ß-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 ß-catenin correlated with histopathological characteristics, suggesting that these markers could predict the disease outcome and the response to treatments.

Heat shock proteins in prostate cancer: from tumorigenesis to the clinic.

The heat shock proteins (HSP) constitute a superfamily of chaperone proteins present in all cells and in all cell compartments, operating in a complex interplay with synergistic/overlapping multiplicity of functions, even though the common effect is cell protection. Several reasons explain the need for investigating HSP in prostate cancer: (1) these molecules function as chaperones of tumorigenesis accompanying the emergence of prostate cancer cells, (2) they appear as useful molecular markers associated with disease aggressiveness and with resistance to anticancer therapies including hormone therapy, radiotherapy, chemotherapy and hyperthermia, and (3) they can be used as targets for therapies. The latter can be accomplished by: (i) interrupting the interaction of HSP (mainly HSPC1) with various client proteins that are protected from degradation when chaperoned by the HSP; (ii) using the chaperone and adjuvant capabilities of certain HSP to present antigenic peptides to the immune system, so this system can recognise the prostate tumour cells as foreign to mount an effective antitumoral response; and (iii) using treatment planning models taking into account the HSP expression levels to obtain more effective therapies. In summary, the study of the HSP during tumorigenesis as well as during cancer progression, and the inclusion of treatment designs targeting HSP combined with other treatment modalities, should improve prostate cancer survival in the near future.