FKBP51 expressed by both normal epithelial cells and adenocarcinoma of colon suppresses proliferation of colorectal adenocarcinoma

Overexpressed FKBP5 mediates colorectal cancer progression and sensitivity to FK506 treatment via the NF-κB signaling pathway

Colorectal cancer (CRC) is a common and deadly tumor. FK506-binding protein 5 (FKBP5) is associated with some cancers, but the role of FKBP5 in CRC is not clear. The present study aimed to reveal the relationship between FKBP5 and CRC and to uncover the roles of FK506 in CRC. In total, 96 CRC patients were recruited. Survival analysis was conducted using the Kaplan-Meier method and COX regression analyses. Bioinformatics analyses were performed to explore the functions of FKBP5. The mechanisms of FKBP5 and the roles of FK506 in CRC progression were clarified by immunohistochemistry, MTS, scratch assay, transwell and flow cytometric analyses via in vitro and in vivo experiments. FKBP5 was overexpressed in 77 cancer tissues compared to that in matched normal tissues, and the overall survival rate of these patients was relatively shorter. Bioinformatics analyses showed that FKBP5 regulates proliferation, invasion, migration, epithelial-mesenchymal transition and nuclear factor-kappa B (NF-κB) signaling. The upregulation or downregulation of FKBP5 dramatically increases or decreases the proliferation, invasion and migration abilities of CRC cells. The expression of NF-κB, inhibitor B kinase α, matrix metalloproteinase-2 and metalloproteinase-9 positively correlated with FKBP5. FK506 inhibits the progression of CRC via the FKBP5/NF-κB signaling pathway. Our study identified a regulatory role for FKBP5 in CRC progression. Therefore, targeting FKBP5 may provide a novel treatment approach for CRC. FK506 can inhibit the progression of CRC by restraining the FKBP5/NF-κB signaling pathway and is expected to become a new drug for the treatment of CRC.

FK506-binding protein 5 promotes the progression of papillary thyroid carcinoma

Objective

To detect the expression of FK506-binding protein 5 (FKBP5) in human papillary thyroid carcinoma (PTC) tissues, and explore its possible role in the progression of PTC.

Methods

FKBP5 expression levels were assessed in 115 PTC tissues and corresponding normal tissues by immunohistochemistry. We also examined the correlations between FKBP5 expression and clinicopathological factors and survival in 75 patients with PTC. The effects of FKBP5 on the proliferation and apoptosis of PTC cells were detected by colony-formation, MTT, and flow cytometry assays, respectively. We further investigated the effects of FKBP5 on tumor growth in mice.

Results

We revealed high expression levels of FKBP5 in human PTC tissues compared with normal tissues. Furthermore, high FKBP5 expression was associated with an increased incidence of intraglandular dissemination, and lower overall and progression-free survival. FKBP5 depletion remarkably suppressed the proliferation and induced apoptosis of PTC cells in vitro. FKBP5 further contributed to the growth of PTC tumors in mice.

Conclusions

The results of this study demonstrated the potential involvement of FKBP5 in the progression of PTC, and confirmed FKBP5 as a novel therapeutic target for PTC treatment.

IQGAP1, AmotL2, and FKBP51 Scaffoldins in the Glioblastoma Microenvironment

Glioblastoma (GB) is the most frequently occurring and aggressive primary brain tumor. Glioma stem cells (GSCs) and astrocytoma cells are the predominant malignant cells occurring in GB besides a highly heterogeneous population of migrating, neovascularizing and infiltrating myeloid cells that forms a complex tumor microenvironment (TME). Cross talk between the TME cells is pivotal in the biology of this tumor and, consequently, adaptor proteins at critical junctions of signaling pathways may be crucial. Scaffold proteins (scaffolins or scaffoldins) integrate external and internal stimuli to regulate various signaling pathways, interacting simultaneously with multiple proteins involved. We investigated by double and triple immunofluorescence the localization of IQGAP1, AmotL2, and FKBP51, three closely related scaffoldins, in malignant cells and TME of human GB tumors. We found that IQGAP1 is preferentially expressed in astrocytoma cells, AmotL2 in GSCs, and FKBP51 in white blood cells in human GB tumors. As GSCs are specially the target for novel therapies, we will investigate in further studies whether AmotL2 inhibition is effective in the treatment of GB.

Biological Actions of the Hsp90-binding Immunophilins FKBP51 and FKBP52

Immunophilins are a family of proteins whose signature domain is the peptidylprolyl-isomerase domain. High molecular weight immunophilins are characterized by the additional presence of tetratricopeptide-repeats (TPR) through which they bind to the 90-kDa heat-shock protein (Hsp90), and via this chaperone, immunophilins contribute to the regulation of the biological functions of several client-proteins. Among these Hsp90-binding immunophilins, there are two highly homologous members named FKBP51 and FKBP52 (FK506-binding protein of 51-kDa and 52-kDa, respectively) that were first characterized as components of the Hsp90-based heterocomplex associated to steroid receptors. Afterwards, they emerged as likely contributors to a variety of other hormone-dependent diseases, stress-related pathologies, psychiatric disorders, cancer, and other syndromes characterized by misfolded proteins. The differential biological actions of these immunophilins have been assigned to the structurally similar, but functionally divergent enzymatic domain. Nonetheless, they also require the complementary input of the TPR domain, most likely due to their dependence with the association to Hsp90 as a functional unit. FKBP51 and FKBP52 regulate a variety of biological processes such as steroid receptor action, transcriptional activity, protein conformation, protein trafficking, cell differentiation, apoptosis, cancer progression, telomerase activity, cytoskeleton architecture, etc. In this article we discuss the biology of these events and some mechanistic aspects.

Commitment of Scaffold Proteins in the Onco-Biology of Human Colorectal Cancer and Liver Metastases after Oxaliplatin-Based Chemotherapy

Scaffold proteins play pivotal roles in the regulation of signaling pathways, integrating external and internal stimuli to various cellular outputs. We report the pattern of cellular and subcellular expression of scaffoldins angiomotin-like 2 (AmotL2), FK506 binding protein 5 (FKBP51) and IQ motif containing GTPase-activating protein 1 (IQGAP1) in colorectal cancer (CRC) and metastases in liver resected after oxaliplatin-based chemotherapy (CT). Positive immunostaining for the three scaffoldins was found in most cells in healthy colon, tumor, healthy liver and metastasized liver. The patterns of expression of AmotL2, FKBP51 and IQGAP1 show the greatest variability in immune system cells and neurons and glia cells and the least in blood vessel cells. The simultaneous subcellular localization in tumor cells and other cell types within the tumor suggest an involvement of these three scaffoldins in cancer biology, including a role in Epithelial Mesenchymal Transition. The display in differential localization and quantitative expression of AmotL2, FKBP51, and IQGAP1 could be used as biomarkers for more accurate tumor staging and as potential targets for anti-cancer therapeutics by blocking or slowing down their interconnecting functions. Tough further research needs to be done in order to improve these assessments.

Hsp90-binding immunophilin FKBP51 forms complexes with hTERT enhancing telomerase activity

FK506-binding proteins are members of the immunophilin family of proteins. Those immunophilins associated to the 90-kDa-heat-shock protein, Hsp90, have been proposed as potential modulators of signalling cascade factors chaperoned by Hsp90. FKBP51 and FKBP52 are the best characterized Hsp90-bound immunophilins first described associated to steroid-receptors. The reverse transcriptase subunit of telomerase, hTERT, is also an Hsp90 client-protein and is highly expressed in cancer cells, where it is required to compensate the loss of telomeric DNA after each successive cell division. Because FKBP51 is also a highly expressed protein in cancer tissues, we analyzed its potential association with hTERT·Hsp90 complexes and its possible biological role. In this study it is demonstrated that both immunophilins, FKBP51 and FKBP52, co-immunoprecipitate with hTERT. The Hsp90 inhibitor radicicol disrupts the heterocomplex and favors the partial cytoplasmic relocalization of hTERT in similar manner as the overexpression of the TPR-domain peptide of the immunophilin. While confocal microscopy images show that FKBP51 is primarily localized in mitochondria and hTERT is totally nuclear, upon the onset of oxidative stress, FKBP51 (but not FKBP52) becomes mostly nuclear colocalizing with hTERT, and longer exposure times to peroxide favors hTERT export to mitochondria. Importantly, telomerase activity of hTERT is significantly enhanced by FKBP51. These observations support the emerging role assigned to FKBP51 as antiapoptotic factor in cancer development and progression, and describe for the first time the potential role of this immunophilin favoring the clonal expansion by enhancing telomerase activity.

Expression and localization of the immunophilin FKBP51 in colorectal carcinomas and primary metastases, and alterations following oxaliplatin-based chemotherapy

The immunophilin FK506-binding protein 5 (FKBP51) is a scaffold protein that serves a pivotal role in the regulation of multiple signaling pathways, integrating external and internal stimuli into distinct signal outputs. In a previous study, we identified several genes that are significantly up- or downregulated in the peripheral white cells (PWCs) of colorectal adenocarcinoma (CRC) patients undergoing oxaliplatin-based chemotherapy. In our screening, FKBP51 gene expression was downregulated following chemotherapy. In order to determine whether this alteration in gene expression observed in PWCs may be detected at the protein level in tumors and metastases following the administration of adjuvant chemotherapy, an immunohistochemical analysis of FKBP51 in CRC and primary metastasis tissues was performed. The present study confirmed the downregulation of FKBP51 gene expression elicited by chemotherapy with folinic acid (leucovorin), fluorouracil and oxaliplatin in metastasized liver tissue that had been resected after the oxaliplatin-based chemotherapy, compared with tissue section samples of CRC from patients (prior to antineoplastic treatment). Furthermore, the results indicated that, in CRC tissue sections, the expression of FKBP51 protein is associated with an immature phenotype of stromal fibroblasts and with the epithelial-to-mesenchymal transition (EMT) phenotype, suggesting a role for this protein in the EMT process in CRC. Finally, the observation that only certain cells of the stroma express FKBP51 protein suggests a potential role for this immunophilin as a stroma cell subtype marker.

Androgen Receptor and Androgen-Responsive Gene FKBP5 Are Independent Prognostic Indicators for Esophageal Adenocarcinoma

BACKGROUND

Esophageal adenocarcinoma is a male-dominant disease, but the role of androgens is unclear.

AIMS

To examine the expression and clinical correlates of the androgen receptor (AR) and the androgen-responsive gene FK506-binding protein 5 (FKBP5) in esophageal adenocarcinoma.

METHODS

Expression of AR and FKBP5 was determined by immunohistochemistry. The effect of the AR ligand 5α-dihydrotestosterone (DHT) on the expression of a panel of androgen-responsive genes was measured in AR-positive and AR-negative esophageal adenocarcinoma cell lines. Correlations in expression between androgen-responsive genes were analyzed in an independent cohort of esophageal adenocarcinoma tissues.

RESULTS

There was AR staining in 75 of 77 cases (97 %), and FKBP5 staining in 49 (64 %), all of which had nuclear AR. Nuclear AR with FKBP5 expression was associated with decreased median survival (451 vs. 2800 days) and was an independent prognostic indicator (HR 2.894, 95 % CI 1.396–6.002, p = 0.0043) in multivariable Cox proportional hazards models. DHT induced a significant increase in expression of the androgen-responsive genes FKBP5, HMOX1, FBXO32, VEGFA, WNT5A, and KLK3 only in AR-positive cells in vitro. Significant correlations in expression were observed between these androgen-responsive genes in an independent cohort of esophageal adenocarcinoma tissues.

CONCLUSION

Nuclear AR and expression of FKBP5 is associated with decreased survival in esophageal adenocarcinoma.

Biological relevance of Hsp90-binding immunophilins in cancer development and treatment

Immunophilins are a family of intracellular receptors for immunosuppressive drugs. Those immunophilins that are related to immunosuppression are the smallest proteins of the family, i.e., FKBP12 and CyPA, whereas the other members of the family have higher molecular weight because the show additional domains to the drug-binding site. Among these extra domains, the TPR-domain is perhaps the most relevant because it permits the interaction of high molecular weight immunophilins with the 90-kDa heat-shock protein, Hsp90. This essential molecular chaperone regulates the biological function of several protein-kinases, oncogenes, protein phosphatases, transcription factors and cofactors . Hsp90-binding immunophilins where first characterized due to their association with steroid receptors. They regulate the cytoplasmic transport and the subcellular localization of these and other Hsp90 client proteins, as well as transcriptional activity, cell proliferation, cell differentiation and apoptosis. Hsp90-binding immunophilins are frequently overexpressed in several types of cancers and play a key role in cell survival. In this article we analyze the most important biological actions of the best characterized Hsp90-binding immunophilins in both steroid receptor function and cancer development and discuss the potential use of these immunophilins for therapeutic purposes as potential targets of specific small molecules.

Analysis of gene expression for studying tumor progression: the case of glucocorticoid administration

BACKGROUND

Glucocorticoids are commonly used as adjuvant treatment for side-effects and have anti-proliferative activity in several tumors but, on the other hand, their proliferative effect has been reported in several studies, some of them involving the spread of cancer. We shall attempt to reconcile these incongruities from the genomic and tissue-physiology perspectives with our findings.

METHODS

An accurate phenotype analysis of microarray data can help to solve multiple paradoxes derived from tumor-progression models. We have developed a new strategy to facilitate the study of interdependences among the phenotypes defined by the sample clusters obtained by common clustering methods (HC, SOTA, SOM, PAM). These interdependences are obtained by the detection of non-linear expression-relationships where each fluctuation in the relationship implies a phenotype change and each relationship typology implies a specific phenotype interdependence. As a result, multiple phenotypic changes are identified together with the genes involved in the phenotype transitions. In this way, we study the phenotypic changes from microarray data that describe common phenotypes in cancer from different tissues, and we cross our results with biomedical databases to relate the glucocorticoid activity to the phenotypic changes.

RESULTS

11,244 significant non-linear expression relationships, classified into 11 different typologies, have been detected from the data matrix analyzed. From them, 415 non-linear expression relationships were related to glucocorticoid activity. Studying them, we have found the possible reason for opposite effects of some stressor agents like dexamethasone on tumor progression and it has been confirmed by literature. This hidden reason has resulted in being linked with the type of tumor progression of the tissues. In the first type of tumor progression found, new cells can be stressed during proliferation and stressor agents increase tumor proliferation. In the second type, cell stress and tumor proliferation are antagonists so, therefore, stressor agents stop tumor proliferation in order to stress the cells. The non-linear expression relationships among DUSP6, FERMT2, FKBP5, EGFR, NEDD4L and CITED2 genes are used to synthesize these findings.

Hsp90-binding immunophilins as a potential new platform for drug treatment

Immunophilins are proteins that contain a PPIase domain as a family signature. Low-molecular-weight immunophilins were first described associated to immunosuppressive action and protein folding. Recent studies of other members of the family have led to the identification of their participation in basic processes such as protein-protein interactions, signal transduction cascades, cell differentiation, cell cycle progression, metabolic activity, apoptosis mechanisms, microorganisms infection, cancer, neurotrophism and neuroprotection, among several other physiological and pathophysiological processes. Due to all these emerging features, the development of specific ligands for immunophilins appears to have promising perspectives, in particular in the fields of cancer biology and neuroregeneration fields. We review the emerging role of immunophilins in protein transport, transcription regulation, malignancies development and neurotrophic action, in addition to a number of biological properties that transform these proteins in potential targets for novel therapeutic strategies.

FKBP51 and FKBP52 in signaling and disease

FKBP51 and FKBP52 are diverse regulators of steroid hormone receptor signaling, including receptor maturation, hormone binding and nuclear translocation. Although structurally similar, they are functionally divergent, which is largely attributed to differences in the FK1 domain and the proline-rich loop. FKBP51 and FKBP52 have emerged as likely contributors to a variety of hormone-dependent diseases, including stress-related diseases, immune function, reproductive functions and a variety of cancers. In addition, recent studies have implicated FKBP51 and FKBP52 in Alzheimer's disease and other protein aggregation disorders. This review summarizes our current understanding of FKBP51 and FKBP52 interactions within the receptor-chaperone complex, their contributions to health and disease, and their potential as therapeutic targets for the treatment of these diseases.

The emerging role of FK506-binding proteins as cancer biomarkers: a focus on FKBPL

FKBPs (FK506-binding proteins) have long been recognized as key regulators of the response to immunosuppressant drugs and as co-chaperones of steroid receptor complexes. More recently, evidence has emerged suggesting that this diverse protein family may also represent cancer biomarkers owing to their roles in cancer progression and response to treatment. FKBPL (FKBP-like) is a novel FKBP with roles in GR (glucocorticoid receptor), AR (androgen receptor) and ER (oestrogen receptor) signalling. FKBPL binds Hsp90 (heat-shock protein 90) and modulates translocation, transcriptional activation and phosphorylation of these steroid receptors. It has been proposed as a novel prognostic and predictive biomarker, where high levels predict for increased recurrence-free survival in breast cancer patients and enhanced sensitivity to endocrine therapy. Since this protein family has roles in a plethora of signalling pathways, its members represent novel prognostic markers and therapeutic targets for cancer diagnosis and treatment.

Immunohistochemical analysis of FKBP51 in human cancers

FKBP51 is a FK506-binding immunophilin involved in the regulation of several fundamental biological processes. A growing body of data indicates that this protein has also a role in the abnormal cell growth of cancers, and could be considered as a promising new marker of tumor progression and response to radio/chemotherapy. However, the data concerning the expression of FKBP51 in cancer are not conclusive, and partially contradictory. They delineate a very complex scenario, in which many molecular FKBP51-related pathways are variously intersected among different tumors. This review reports the available data concerning FKBP51 expression in normal tissues and human malignancies, outlining the role of the immunohistochemical analysis as a fundamental tool for better understanding the role of this immunophilin in cancer biology.

FKBP family proteins as promising new biomarkers for cancer

FK506-binding proteins (FKBPs) belong to the immunophilin family and bind immunosuppressive drugs, such as FK506 and rapamycin. These proteins, through interactions with steroid hormone receptors, kinases, or other cellular factors, play important roles in various physiological processes and, more interestingly, in pathological processes in mammals. Accumulating evidence has implicated some FKBP members in a variety of processes, such as the cell cycle and survival and apoptotic signaling pathways, particularly in cancers. After the deregulation of their expression was observed in cancer tissues, it became increasingly clear that FKBP members played an important role in tumorigenesis and the response to chemotherapies and radiotherapies and that FKBP members could act as oncogenes or tumor suppressors depending on the tissue type. A wealth of data from in vitro and clinical studies is paving the way for novel, promising roles of FKBPs as diagnostic, prognostic or therapy-monitoring cancer biomarkers.

The role of FKBP5 in cancer aetiology and chemoresistance

FK506 binding protein 51 (FKBP51, also called FKBP5) belongs to a family of immunophilins, FK506 binding proteins (FKBPs). Members of this family are targets for drugs such as rapamycin and cyclosporine. Although FKBP5 shares characteristics with other FKBPs, it also has unique features, especially its role in the regulation of multiple signalling pathways and in tumourigenesis and chemoresistance. In this review, we will focus on the recently discovered role of FKBP5 in cancer aetiology and response to antineoplastic therapy.