High level of αB-crystallin contributes to the progression of osteosarcoma

MicroRNAs as the pivotal regulators of cisplatin resistance in osteosarcoma

Osteosarcoma (OS) is an aggressive bone tumor that originates from mesenchymal cells. It is considered as the eighth most frequent childhood cancer that mainly affects the tibia and femur among the teenagers and young adults. OS can be usually diagnosed by a combination of MRI and surgical biopsy. The intra-arterial cisplatin (CDDP) and Adriamycin is one of the methods of choices for the OS treatment. CDDP induces tumor cell death by disturbing the DNA replication. Although, CDDP has a critical role in improving the clinical complication in OS patients, a high ratio of CDDP resistance is observed among these patients. Prolonged CDDP administrations have also serious side effects in normal tissues and organs. Therefore, the molecular mechanisms of CDDP resistance should be clarified to define the novel therapeutic modalities in OS. Multidrug resistance (MDR) can be caused by various cellular and molecular processes such as drug efflux, detoxification, and signaling pathways. MicroRNAs (miRNAs) are the key regulators of CDDP response by the post transcriptional regulation of target genes involved in MDR. In the present review we have discussed all of the miRNAs associated with CDDP response in OS cells. It was observed that the majority of reported miRNAs increased CDDP sensitivity in OS cells through the regulation of signaling pathways, apoptosis, transporters, and autophagy. This review highlights the miRNAs as reliable non-invasive markers for the prediction of CDDP response in OS patients.

Autophagy, molecular chaperones, and unfolded protein response as promoters of tumor recurrence

Tumor recurrence is a paradoxical function of a machinery, whereby a small proportion of the cancer cell population enters a resistant, dormant state, persists long-term in this condition, and then transitions to proliferation. The dormant phenotype is typical of cancer stem cells, tumor-initiating cells, disseminated tumor cells, and drug-tolerant persisters, which all demonstrate similar or even equivalent properties. Cancer cell dormancy and its conversion to repopulation are regulated by several protein signaling systems that inhibit or induce cell proliferation and provide optimal interrelations between cancer cells and their special niche; these systems act in close connection with tumor microenvironment and immune response mechanisms. During dormancy and reawakening periods, cell proteostasis machineries, autophagy, molecular chaperones, and the unfolded protein response are recruited to protect refractory tumor cells from a wide variety of stressors and therapeutic insults. Proteostasis mechanisms functionally or even physically interfere with the main regulators of tumor relapse, and the significance of these interactions and implications in the tumor recurrence phases are discussed in this review.

Alpha-B-Crystallin overexpression is sufficient to promote tumorigenesis and metastasis in mice

BACKGROUND

αB-Crystallin is a heat shock chaperone protein which binds to misfolded proteins to prevent their aggregation. It is overexpressed in a wide-variety of cancers. Previous studies using human cancer cell lines and human xenograft models have suggested potential tumor promoter (oncogene) roles for αB-Crystallin in a wide-spectrum of cancers.

METHODS

To determine the causal relationship between CRYAB overexpression and cancer, we generated a Cryab overexpression knock-in mouse model and monitor them for development of spontaneous and carcinogen (DMBA)-induced tumorigenesis. In order to investigate the mechanism of malignancies observed in this model multiple techniques were used such as immunohistochemical characterizations of tumors, bioinformatics analysis of publically available human tumor datasets, and generation of mouse embryonic fibroblasts (MEFs) for in vitro assays (clonogenic survival and migration assays and proteome analysis by mass-spectrometry).

RESULTS

This model revealed that constitutive overexpression of Cryab results in the formation of a variety of lethal spontaneous primary and metastatic tumors in mice. In vivo, the overexpression of Cryab correlated with the upregulation of epithelial-to-mesenchymal (EMT) markers, angiogenesis and some oncogenic proteins including Basigin. In vitro, using E1A/Ras transformed MEFs, we observed that the overexpression of Cryab led to the promotion of cell survival via upregulation of Akt signaling and downregulation of pro-apoptotic pathway mediator JNK, with subsequent attenuation of apoptosis as assessed by cleaved caspase-3 and Annexin V staining.

CONCLUSIONS

Overall, through the generation and characterization of Cryab overexpression model, we provide evidence supporting the role of αB-Crystallin as an oncogene, where its upregulation is sufficient to induce tumors, promote cell survival and inhibit apoptosis.

Mass Spectrometric-Based Proteomics for Biomarker Discovery in Osteosarcoma: Current Status and Future Direction

Due to a lack of novel therapies and biomarkers, the clinical outcomes of osteosarcoma patients have not significantly improved for decades. The advancement of mass spectrometry (MS), peptide quantification, and downstream pathway analysis enables the investigation of protein profiles across a wide range of input materials, from cell culture to long-term archived clinical specimens. This can provide insight into osteosarcoma biology and identify candidate biomarkers for diagnosis, prognosis, and stratification of chemotherapy response. In this review, we provide an overview of proteomics studies of osteosarcoma, indicate potential biomarkers that might be promising therapeutic targets, and discuss the challenges and opportunities of mass spectrometric-based proteomics in future osteosarcoma research.

Osteosarcoma and Metastasis

Osteosarcoma is the most common primary bone malignancy in adolescents. Its high propensity to metastasize is the leading cause for treatment failure and poor prognosis. Although the research of osteosarcoma has greatly expanded in the past decades, the knowledge and new therapy strategies targeting metastatic progression remain sparse. The prognosis of patients with metastasis is still unsatisfactory. There is resonating urgency for a thorough and deeper understanding of molecular mechanisms underlying osteosarcoma to develop innovative therapies targeting metastasis. Toward the goal of elaborating the characteristics and biological behavior of metastatic osteosarcoma, it is essential to combine the diverse investigations that are performed at molecular, cellular, and animal levels from basic research to clinical translation spanning chemical, physical sciences, and biology. This review focuses on the metastatic process, regulatory networks involving key molecules and signaling pathways, the role of microenvironment, osteoclast, angiogenesis, metabolism, immunity, and noncoding RNAs in osteosarcoma metastasis. The aim of this review is to provide an overview of current research advances, with the hope to discovery druggable targets and promising therapy strategies for osteosarcoma metastasis and thus to overcome this clinical impasse.

With or without You: Co-Chaperones Mediate Health and Disease by Modifying Chaperone Function and Protein Triage

Heat shock proteins (HSPs) are a family of molecular chaperones that regulate essential protein refolding and triage decisions to maintain protein homeostasis. Numerous co-chaperone proteins directly interact and modify the function of HSPs, and these interactions impact the outcome of protein triage, impacting everything from structural proteins to cell signaling mediators. The chaperone/co-chaperone machinery protects against various stressors to ensure cellular function in the face of stress. However, coding mutations, expression changes, and post-translational modifications of the chaperone/co-chaperone machinery can alter the cellular stress response. Importantly, these dysfunctions appear to contribute to numerous human diseases. Therapeutic targeting of chaperones is an attractive but challenging approach due to the vast functions of HSPs, likely contributing to the off-target effects of these therapies. Current efforts focus on targeting co-chaperones to develop precise treatments for numerous diseases caused by defects in protein quality control. This review focuses on the recent developments regarding selected HSP70/HSP90 co-chaperones, with a concentration on cardioprotection, neuroprotection, cancer, and autoimmune diseases. We also discuss therapeutic approaches that highlight both the utility and challenges of targeting co-chaperones.

Small Heat Shock Proteins in Cancers: Functions and Therapeutic Potential for Cancer Therapy

Small heat shock proteins (sHSPs) are ubiquitous ATP-independent chaperones that play essential roles in response to cellular stresses and protein homeostasis. Investigations of sHSPs reveal that sHSPs are ubiquitously expressed in numerous types of tumors, and their expression is closely associated with cancer progression. sHSPs have been suggested to control a diverse range of cancer functions, including tumorigenesis, cell growth, apoptosis, metastasis, and chemoresistance, as well as regulation of cancer stem cell properties. Recent advances in the field indicate that some sHSPs have been validated as a powerful target in cancer therapy. In this review, we present and highlight current understanding, recent progress, and future challenges of sHSPs in cancer development and therapy.

High level of RNF187 contributes to the progression and drug resistance of osteosarcoma

Objectives: Ring finger protein 187 (RNF187) was recently demonstrated to be up-regulation and function as a promoter in multiple cancers. However, the roles of RNF187 in osteosarcoma (OS) are unclear. Here, we tried to reveal the clinicopathological and biological roles of RNF187 in OS. Materials and Methods: We employed the quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) to determine the expression of RNF187 in OS tissues and cells. Migration and invasion capacities were analyzed by wound healing and transwell assays, and colony formation and CCK8 assays were performed to investigate proliferative ability. The functional effects of RNF187 on OS drugs resistance were further determined by CCK8 and western blot assays. Then, the relationship between RNF187 expression and clinical implications was analyzed by tissue microarrays (TMAs) including 51 OS cases. Moreover, the prognostic value was also determined by Kaplan-Meier analysis. Results: We reported that RNF187 mRNA was significantly increased in OS tissues compared to matched nontumorous tissues (3.83 ±0.79 vs. 1.70 ± 0.63), which was in line with the IHC assay in TMAs. By RNA interference and cDNA transfection, we showed high level of RNF187 increased the migration, invasion and proliferation of OS cells. Moreover, we demonstrated that elevated RNF187 expression induced OS cell drugs resistance, activated the ERK1/2 molecular and markedly enhanced the BCL-2 expression. Clinically, OS patients with high level of RNF187 was associated with Histologic differentiation (p=0.001), an advanced Enneking stage (p=0.001), response to chemotherapy (p=0.004), and metastasis (p= 0.001). Clinically, our data displayed that the RNF187 overexpression in OS samples associated with shorten overall survival (p=0.001) and high tumor recurrence (p=0.001) in postoperative OS patients. Conclusions: Our results indicate that Elevated RNF187 expression is a new adverse outcomes marker for OS patients and may be used as a new therapeutic target of OS.

Progression of the role of CRYAB in signaling pathways and cancers

CRYAB is a member of the small heat shock protein family, first discovered in the lens of the eye, and involved in various diseases, such as eye and heart diseases and even cancers, for example, breast cancer, lung cancer, prostate cancer, and ovarian cancer. In addition, CRYAB proteins are involved in a variety of signaling pathways including apoptosis, inflammation, and oxidative stress. This review summarizes the recent progress concerning the role of CRYAB in signaling pathways and diseases. Therefore, the role of CRYAB in signaling pathways and cancers is urgently needed. This article reviews the regulation of CRYAB in the apoptotic inflammatory signaling pathway and its role in cancers progression and as a key role in anti-cancer therapy targeting CRYAB in an effort to improve outcomes for patients with metastatic disease.

Integrative analysis of transcriptomics and clinical data uncovers the tumor-suppressive activity of MITF in prostate cancer

The dysregulation of gene expression is an enabling hallmark of cancer. Computational analysis of transcriptomics data from human cancer specimens, complemented with exhaustive clinical annotation, provides an opportunity to identify core regulators of the tumorigenic process. Here we exploit well-annotated clinical datasets of prostate cancer for the discovery of transcriptional regulators relevant to prostate cancer. Following this rationale, we identify Microphthalmia-associated transcription factor (MITF) as a prostate tumor suppressor among a subset of transcription factors. Importantly, we further interrogate transcriptomics and clinical data to refine MITF perturbation-based empirical assays and unveil Crystallin Alpha B (CRYAB) as an unprecedented direct target of the transcription factor that is, at least in part, responsible for its tumor-suppressive activity in prostate cancer. This evidence was supported by the enhanced prognostic potential of a signature based on the concomitant alteration of MITF and CRYAB in prostate cancer patients. In sum, our study provides proof-of-concept evidence of the potential of the bioinformatics screen of publicly available cancer patient databases as discovery platforms, and demonstrates that the MITF-CRYAB axis controls prostate cancer biology.

Krüppel-like factor 4 promotes human osteosarcoma growth and metastasis via regulating CRYAB expression

Krüppel-like factor 4 (KLF4), a zinc-finger transcription factor, is an essential regulator in many cellular processes, including differentiation, proliferation, inflammation, pluripotency, and apoptosis. Along with these roles in normal cells and tissues, KLF4 has been reported as a tumor suppressor or an oncogene in many cancers. However, the role of KLF4 in osteosarcoma is largely unknown. Here we found the expression of KLF4 was significantly increased in human osteosarcoma tissues compared with the normal tissues. Elevated KLF4 promoted human osteosarcoma cell proliferation and metastasis. Subsequently, mechanistic studies revealed KLF4 specifically bound the promoter of CRYAB and upregulated CRYAB expression in human osteosarcoma cells. Moreover, we found that KLF4 enhanced osteosarcoma cell proliferation and migration via upregulating CRYAB. Therefore, our studies suggested KLF4 may be a potential target for human osteosarcoma therapy.

miR-491 Inhibits Osteosarcoma Lung Metastasis and Chemoresistance by Targeting αB-crystallin

Dysregulated microRNAs (miRNAs) play an important role in osteosarcoma (OS) progression. In the present study, we investigate the clinical significance of serum miR-491 level and the potential role of miR-491 in OS lung metastasis and chemoresistance. Clinical data show that the level of miR-491 was decreased in serum from OS patients compared with healthy control subjects, and that a decreased serum miR-491 level is correlated with increased metastasis, poor chemoresponse, and lower survival rate in OS patients. In vitro and in vivo experiments show that overexpression of miR-491 suppresses OS cell lung metastasis, whereas it enhances cisplatin (CDDP)-induced tumor growth inhibition and apoptosis. In contrast, inhibition of miR-491 stimulates OS cell lung metastasis and suppresses CDDP-induced tumor growth inhibition and apoptosis. Furthermore, we demonstrate that miR-491 exerts its role by directly targeting αB-crystallin (CRYAB) in OS. Our findings suggest that serum level of miR-491 has potential as a biomarker for predicting OS progression and prognosis of OS patients. Additionally, restoration of miR-491 may be a novel strategy for inhibiting OS lung metastasis and overcoming OS cell resistance to chemotherapy.

A novel dominant D109A CRYAB mutation in a family with myofibrillar myopathy affects αB-crystallin structure

Myofibrillar myopathy (MFM) is a group of inherited muscular disorders characterized by myofibrils dissolution and abnormal accumulation of degradation products. So far causative mutations have been identified in nine genes encoding Z-disk proteins, including αB-crystallin (CRYAB), a small heat shock protein (also called HSPB5). Here, we report a case study of a 63-year-old Polish female with a progressive lower limb weakness and muscle biopsy suggesting a myofibrillar myopathy, and extra-muscular multisystemic involvement, including cataract and cardiomiopathy. Five members of the proband's family presented similar symptoms. Whole exome sequencing followed by bioinformatic analysis revealed a novel D109A mutation in CRYAB associated with the disease. Molecular modeling in accordance with muscle biopsy microscopic analyses predicted that D109A mutation influence both structure and function of CRYAB due to decreased stability of oligomers leading to aggregate formation. In consequence disrupted sarcomere cytoskeleton organization might lead to muscle pathology. We also suggest that mutated RQDE sequence of CRYAB could impair CRYAB chaperone-like activity and promote aggregation of lens crystallins.

The small heat shock protein αA-crystallin negatively regulates pancreatic tumorigenesis

Our recent study has shown that αA-crystallin appears to act as a tumor suppressor in pancreas. Here, we analyzed expression patterns of αA-crystallin in the pancreatic tumor tissue and the neighbor normal tissue from 74 pancreatic cancer patients and also pancreatic cancer cell lines. Immunocytochemistry revealed that αA-crystallin was highly expressed in the normal tissue from 56 patients, but barely detectable in the pancreatic tumor tissue. Moreover, a low level of αA-crystallin predicts poor prognosis for patients with pancreatic duct adenocarcinoma (PDAC). In the 12 pancreatic cell lines analyzed, except for Capan-1 and Miapaca-2 where the level of αA-crystallin was about 80% and 65% of that in the control cell line, HPNE, the remaining pancreatic cancer cells have much lower αA-crystallin levels. Overexpression of αA-crystallin in MiaPaca-1 cells lacking endogenous αA-crystallin significantly decreased its tumorigenicity ability as shown in the colony formation and wound healing assays. In contrast, knockdown of αA-crystallin in the Capan-1 cells significantly increased its tumorigenicity ability as demonstrated in the above assays. Together, our results further demonstrate that αA-crystallin negatively regulates pancreatic tumorigenesis and appears to be a prognosis biomarker for PDAC.