Phosphorylated Heat Shock Protein 20 (HSPB6) Regulates Transforming Growth Factor-α-Induced Migration and Invasion of Hepatocellular Carcinoma Cells

A new label free spiral sensor using impedance spectroscopy to characterize hepatocellular carcinoma in tissue and serum samples

Hepatocellular carcinoma (HCC) stands as the most prevalent form of primary liver cancer, predominantly affecting patients with chronic liver diseases such as hepatitis B or C-induced cirrhosis. Diagnosis typically involves blood tests (assessing liver functions and HCC biomarkers), imaging procedures such as Computed Tomography (CT) and Magnetic Resonance Imaging (MRI), and liver biopsies requiring the removal of liver tissue for laboratory analysis. However, these diagnostic methods either entail lengthy lab processes, require expensive imaging equipment, or involve invasive techniques like liver biopsies. Hence, there exists a crucial need for rapid, cost-effective, and noninvasive techniques to characterize HCC, whether in serum or tissue samples. In this study, we developed a spiral sensor implemented on a printed circuit board (PCB) technology that utilizes impedance spectroscopy and applied it to 24 tissues and sera samples as proof of concept. This newly devised circuit has successfully characterized HCC and normal tissue and serum samples. Utilizing the distinct dielectric properties between HCC cells and serum samples versus the normal samples across a specific frequency range, the differentiation between normal and HCC samples is achieved. Moreover, the sensor effectively characterizes two HCC grades and distinguishes cirrhotic/non-cirrhotic samples from tissue specimens. In addition, the sensor distinguishes cirrhotic/non-cirrhotic samples from serum specimens. This pioneering study introduces Electrical Impedance Spectroscopy (EIS) spiral sensor for diagnosing HCC and liver cirrhosis in clinical serum-an innovative, low-cost, rapid (< 2 min), and precise PCB-based technology without elaborate sample preparation, offering a novel non-labeled screening approach for disease staging and liver conditions.

Cellular functions of heat shock protein 20 (HSPB6) in cancer: A review

Heat shock proteins (HSP) are a large family of peptide proteins that are widely found in cells. Studies have shown that the expression and function of HSPs in cells are very complex, and they can participate in cellular physiological and pathological processes through multiple pathways. Multiple heat shock proteins are associated with cancer cell growth, proliferation, metastasis, and resistance to anticancer drugs, and they play a key role in cancer development by ensuring the correct folding or degradation of proteins in cancer cells. As research hotspots, HSP90, HSP70 and HSP27 have been extensively studied in cancer so far. However, HSP20, also referred to as HSPB6, as a member of the small heat shock protein family, has been shown to play an important role in the cardiovascular system, but little research has been conducted on HSP20 in cancer. This review summarizes the current cellular functions of HSP20 in different cancer types, as well as its effects on cancer proliferation, progression, prognosis, and its other functions in cancer, to illustrate the close association between HSP20 and cancer. We show that, unlike most HSPs, HSP20 mainly plays an active anticancer role in cancer development, which is expected to provide new ideas and help for cancer diagnosis and treatment and research.

Upregulation by duloxetine of the transforming growth factor-α-induced migration of hepatocellular carcinoma cells via enhancement of the c-Jun N-terminal kinase activity

Duloxetine, a selective reuptake inhibitor for serotonin and norepinephrine, is a medication widely used for major depression. Currently, duloxetine is also recommended for pain related to chemotherapy-induced peripheral neuropathy or cancer. Previously, we showed that transforming growth factor-α (TGF-α) induces the migration of human hepatocellular carcinoma (HCC)-derived HuH7 cells through the activation of c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK) and AKT. In the present study, we investigate whether duloxetine affects cell migration and its mechanism. Duloxetine significantly enhanced the TGF-α-induced migration of HuH7 cells. Fluvoxamine and sertraline, specific inhibitors of serotonin reuptake, also upregulated the TGF-α-induced cell migration. On the contrary, reboxetine, a specific norepinephrine reuptake inhibitor, failed to affect cell migration. Duloxetine significantly amplified the TGF-α-stimulated phosphorylation of JNK, but not p38 MAPK and AKT. In addition, fluvoxamine and sertraline, but not reboxetine, enhanced the phosphorylation of JNK. SP600125, a JNK inhibitor, suppressed the enhancement by duloxetine, fluvoxamine, or sertraline of TGF-α-induced migration of HuH7 cells. Taken together, our results strongly suggest that duloxetine strengthens the TGF-α-induced activation of JNK via inhibition of serotonin reuptake in HCC cells, leading to the enhancement of cell migration.

Heat Shock Protein B7 Inhibits the Progression of Endometrial Carcinoma by Inhibiting PI3K/AKT/mTOR Pathway

PURPOSE

To investigate the role and mechanism of action of Heat shock protein B7 (HSPB7) in endometrial carcinoma (EC).

METHODS

GEPIA (Gene Expression Profiling Interactive Analysis) was used to analyze the expression and prognostic value of HSPB7 in TCGA data. HSPB7 mRNA and protein expression levels were detected by qRT-PCR and Western blot, respectively. EC cell proliferation, apoptosis, migration, and invasion were determined by colony formation, EdU, flow cytometry, and transwell assays. Mitochondrial membrane potential was determined using JC-1 probe. In addition, apoptosis-related and metastasis-related proteins were quantitatively evaluated. A gene set enrichment analysis of the signaling pathways by which HSPB7 influences EC was performed and the levels of enriched pathway-related proteins were evaluated.

RESULTS

We first proved that HSPB7 was downregulated in EC tissues and HSPB7 levels were positively related to survival rates. In functional assays, HSPB7 overexpression suppressed the proliferation, migration, and invasion of EC cells and conversely promoted apoptosis. Moreover, HSPB7 overexpression decreased the mitochondrial membrane potential of EC cells significantly. Bioinformatics analyses revealed that the PI3K/AKT/mTOR pathway was significantly enriched in EC. HSPB7 inhibited the phosphorylation of the PI3K/AKT/mTOR pathway to reduce proliferation, migration and invasion, and increased apoptosis in EC cells.

CONCLUSION

HSPB7 was downregulated in EC and influenced EC cell proliferation, invasion, migration, and apoptosis via the PI3K/AKT/mTOR signaling pathway. These findings provide a novel perspective for the development of EC treatment strategies.

SERMs (selective estrogen receptor modulator), acting as estrogen receptor β agonists in hepatocellular carcinoma cells, inhibit the transforming growth factor-α-induced migration via specific inhibition of AKT signaling pathway

Selective estrogen receptor modulator (SERM) interacts with estrogen receptors and acts as both an agonist or an antagonist, depending on the target tissue. SERM is widely used as a safer hormone replacement therapeutic medicine for postmenopausal osteoporosis. Regarding hepatocellular carcinoma (HCC), accumulating evidence indicates gender differences in the development, and that men are at higher morbidity risk than premenopausal women, suggesting that estrogen protects against HCC. However, it remains unclear whether SERM affects the HCC progression. Previously, we have shown that transforming growth factor (TGF)-α promotes the migration of HCC cells via p38 mitogen-activated protein kinases (MAPK), c-Jun N-terminal kinase and AKT. In the present study, we investigated whether SERM such as tamoxifen, raloxifene and bazedoxifene, affects the HCC cell migration using human HCC-derived HuH7 cells. Raloxifene and bazedoxifene but not tamoxifen, significantly suppressed the TGF-α-induced HuH7 cell migration. ERB041 and DPN, estrogen receptor (ER) β agonists, inhibited the TGF-α-induced cell migration whereas PPT, an ERα agonist, did not show the suppressive effect on the cell migration. ERB041 attenuated the TGF-α-induced phosphorylation of AKT without affecting the phosphorylation of p38 MAPK and c-Jun N-terminal kinase. Raloxifene and bazedoxifene also inhibited the phosphorylation of AKT by TGF-α. Furthermore, PHTPP, an ERβ antagonist, significantly reversed the suppression by both raloxifene and bazedoxifene of the TGF-α-induced cell migration. Taken together, our results strongly indicate that raloxifene and bazedoxifene, SERMs, suppress the TGF-α-induced migration of HCC cells through ERβ-mediated inhibition of the AKT signaling pathway.

GLP-1 reduces the migration of hepatocellular carcinoma cells via suppression of the stress-activated protein kinase/c-Jun N-terminal kinase pathway

Incretins, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), are hormones secreted from small intestine accompanied with oral intake. We previously showed that transforming growth factor (TGF)-α stimulates the migration of hepatocellular carcinoma (HCC) cells via mitogen-activated protein (MAP) kinases, AKT and Rho-kinase. However, it remains to be elucidated whether incretins affect HCC cell functions. In the present study, therefore, we investigated whether incretins affect the migration of HCC cells using human HCC-derived HuH7 cells. GLP-1, but not GIP, reduced both TGF-α- and hepatocyte growth factor (HGF)-induced cell migration. IBMX, an inhibitor of cyclic nucleotide phosphodiesterase, enhanced the suppressive effect of GLP-1. GLP-1 attenuated the phosphorylation of stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) by TGF-α and HGF. Our results strongly suggest that GLP-1 suppresses TGF-α- and HGF-induced migration of HCC cells through inhibiting the SAPK/JNK signaling pathway, and that the inhibition by GLP-1 is due to cAMP production.

Serum Tumor Markers for Early Diagnosis of Primary Hepatocellular Carcinoma

Primary hepatocellular carcinoma (HCC) is one of the most frequently occurring pernicious tumors in the world. It is typically very insidious in the early stages with no obvious symptoms. Its development and metastasis are very rapid. Upon diagnosis, most patients have already reached a local advanced stage or have established distant metastases. The treatment of HCC is limited, with poor prognosis and short natural survival time. In order to improve the efficiency of early diagnosis, it is particularly significant to choose economic and effective diagnosis methods. Ultrasound, magnetic resonance imaging, and computed tomography are usually used in the clinic, but these methods are extremely limited in the diagnosis of HCC. Tumor markers have become the main effective early clinical diagnosis method. Potential serum tumor markers include alpha fetoprotein heterogeneity, Golgi protein 73, phosphatidylinositol proteoglycan (GPC-3), osteopontin, abnormal prothrombin, and heat shock protein. These tumor markers provide new ideas and methods for the diagnosis of HCC. A combination of multiple markers can make up for the deficiency of single marker detection and provide a new strategy for the prognosis and auxiliary diagnosis of HCC. This review introduces protein tumor markers utilized over the past five years.

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.

Heat shock protein 70 positively regulates transforming growth factor-α-induced hepatocellular carcinoma cell migration via the AKT signaling pathway

Heat shock proteins (HSPs) are induced in response to extracellular stress and manage the quality of proteins as molecular chaperones. HSP70, a highly conserved HSP, has been reported to correlate with the proliferation and migration of human cancer cells, such as oral, prostate, lung and liver cancer. Regarding hepatocellular carcinoma (HCC), the HSP70 levels in the tumor tissues from patients are significantly higher than those in the normal liver tissues. HSP70 reportedly upregulates the migration and invasion of HCC. The AKT, p38 mitogen-activated protein kinase (MAPK), c-jun N-terminal kinase (JNK) and Rho-kinase signaling pathways regulate the transforming growth factor (TGF)-α-induced migration of human HCC-derived HuH7 cells. However, the exact mechanism underlying the role of HSP70 in growth factor-induced HCC migration remains unclear. Therefore, in the present study, the mechanism underlying the involvement of HSP70 in TGF-α-induced HCC cell migration was investigated. Treatment with the HSP70 inhibitors VER155008 and YM-08 and the downregulation of HSP70 protein were confirmed to significantly suppress the TGF-α-induced cell migration of HuH7 cells. Both VER155008 and YM-08 reduced the TGF-α-induced phosphorylation of AKT without affecting the phosphorylation of p38 MAPK, JNK or Rho-kinase. These results strongly suggest that HSP70 positively regulates the TGF-α-induced migration of HCC cells via the AKT signaling pathway.

Effect of Arginine on Chaperone-Like Activity of HspB6 and Monomeric 14-3-3ζ

The effect of protein chaperones HspB6 and the monomeric form of the protein 14-3-3ζ (14-3-3ζ_m) on a test system based on thermal aggregation of UV-irradiated glycogen phosphorylase b (UV-Phb) at 37 °C and a constant ionic strength (0.15 M) was studied using dynamic light scattering. A significant increase in the anti-aggregation activity of HspB6 and 14-3-3ζ_m was demonstrated in the presence of 0.1 M arginine (Arg). To compare the effects of these chaperones on UV-Phb aggregation, the values of initial stoichiometry of the chaperone-target protein complex (S₀) were used. The analysis of the S₀ values shows that in the presence of Arg fewer chaperone subunits are needed to completely prevent aggregation of the UV-Phb subunit. The changes in the structures of HspB6 and 14-3-3ζ_m induced by binding of Arg were evaluated by the fluorescence spectroscopy and differential scanning calorimetry. It was suggested that Arg caused conformational changes in chaperone molecules, which led to a decrease in the thermal stability of protein chaperones and their destabilization.

Olive oil polyphenols suppress the TGF-α-induced migration of hepatocellular carcinoma cells

Oleuropein and 3-hydroxytyrosol (3-HT) are natural polyphenols present in olive oil that are known to exhibit potent anti-oxidant activities and exert protective effects against a number of human diseases. In the liver, olive oil polyphenols have been demonstrated to prevent hepatocellular carcinoma (HCC) cell growth. However, little is known about their effects against HCC cell migration. Therefore, the present study investigated whether or not oleuropein and 3-HT were involved in the suppression of transforming growth factor-α (TGF-α)-induced migration of human HCC cells using human HCC-derived HuH7 cells. The TGF-α-induced migration of HuH7 cells was significantly and dose-dependently suppressed by oleuropein and 3-HT. This study group demonstrated previously that the TGF-α-induced activation of AKT and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) were involved in HuH7 cell migration. In addition to these protein kinases, the present study examined the involvement of TGF-α-induced activation of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAPK) and Rho kinase in HuH7 cell migration. TGF-α-induced HuH7 cell migration was decreased by SB203580, a p38 MAPK inhibitor, and Y27632, a Rho kinase inhibitor. However, PD98059, an inhibitor of the upstream kinase activating ERK, did not suppress the TGF-α-induced migration of HuH7 cells. Although AKT, SAPK/JNK, p38 MAPK and Rho kinase pathways were suggested to be involved in the TGF-α-induced migration of HuH7 cells, 10-30 µM 3-HT did not exhibit any suppressive effect on the TGF-α-stimulated activities of these kinases. The results of the present study suggest that olive oil polyphenols suppressed the TGF-α-induced migration of HCC cells.

Dodecameric structure of a small heat shock protein from Mycobacterium marinum M

Small heat shock proteins (sHSPs) are ATP-independent molecular chaperones present ubiquitously in all kingdoms of life. Their low molecular weight subunits associate to form higher order structures. Under conditions of stress, sHSPs prevent aggregation of substrate proteins by undergoing rapid changes in their conformation or stoichiometry. Polydispersity and dynamic nature of these proteins have made structural investigations through crystallography a daunting task. In pathogens like Mycobacteria, sHSPs are immuno-dominant antigens, enabling survival of the pathogen within the host and contributing to disease persistence. We characterized sHSPs from Mycobacterium marinum M and determined the crystal structure of one of these. The protein crystallized in three different conditions as dodecamers, with dimers arranged in a tetrahedral fashion to form a closed cage-like architecture. Interestingly, we found a pentapeptide bound to the dodecamers revealing one of the modes of sHSP-substrate interaction. Further, we have observed that ATP inhibits the chaperoning activity of the protein.

Sphingosine 1-phosphate (S1P) reduces hepatocyte growth factor-induced migration of hepatocellular carcinoma cells via S1P receptor 2

A bioactive lipid, sphingosine 1-phosphate (S1P), acts extracellularly as a potent mediator, and is implicated in the progression of various cancers including hepatocellular carcinoma (HCC). S1P exerts its functions by binding to five types of specific receptors, S1P receptor 1 (S1PR1), S1PR2, S1PR3, S1PR4 and S1PR5 on the plasma membrane. However, the exact roles of S1P and each S1PR in HCC cells remain to be clarified. In the present study, we investigated the effect of S1P on the hepatocyte growth factor (HGF)-induced migration of human HCC-derived HuH7 cells, and the involvement of each S1PR. S1P dose-dependently reduced the HGF-induced migration of HuH7 cells. We found that all S1PRs exist in the HuH7 cells. Among each selective agonist for five S1PRs, CYM5520, a selective S1PR2 agonist, significantly suppressed the HGF-induced HuH7 cell migration whereas selective agonists for S1PR1, S1PR3, S1PR4 or S1PR5 failed to affect the migration. The reduction of the HGF-induced migration by S1P was markedly reversed by treatment of JTE013, a selective antagonist for S1PR2, and S1PR2- siRNA. These results strongly suggest that S1P reduces the HGF-induced HCC cell migration via S1PR2. Our findings may provide a novel potential of S1PR2 to therapeutic strategy for metastasis of HCC.

Transformation-induced stress at telomeres is counteracted through changes in the telomeric proteome including SAMHD1

The authors apply telomeric chromatin analysis to identify factors that accumulate at telomeres during cellular transformation, promoting telomere replication and repair and counteracting oncogene-borne telomere replication stress.

Telomeres play crucial roles during tumorigenesis, inducing cellular senescence upon telomere shortening and extensive chromosome instability during telomere crisis. However, it has not been investigated if and how cellular transformation and oncogenic stress alter telomeric chromatin composition and function. Here, we transform human fibroblasts by consecutive transduction with vectors expressing hTERT, the SV40 early region, and activated H-RasV12. Pairwise comparisons of the telomeric proteome during different stages of transformation reveal up-regulation of proteins involved in chromatin remodeling, DNA repair, and replication at chromosome ends. Depletion of several of these proteins induces telomere fragility, indicating their roles in replication of telomeric DNA. Depletion of SAMHD1, which has reported roles in DNA resection and homology-directed repair, leads to telomere breakage events in cells deprived of the shelterin component TRF1. Thus, our analysis identifies factors, which accumulate at telomeres during cellular transformation to promote telomere replication and repair, resisting oncogene-borne telomere replication stress.

HSP20 Exerts a Protective Effect on Preeclampsia by Regulating Function of Trophoblast Cells Via Akt Pathways

Preeclampsia (PE) remains the leading cause of maternal and fetal morbidity and mortality. Excessive apoptosis of the placenta and poor remodeling of spiral arteries caused by insufficient invasion of trophoblast cells into uterus have been implicated in the pathogenesis of PE. Accumulating evidence showed that heat shock protein 20 (HSP20) is closely associated with the proliferation, apoptosis, and metastasis of tumor cells. However, little is known about whether HSP20 plays a role in the development of PE. In this study, we detected the apoptosis index and the expressions of HSP20 and apoptosis-associated proteins in the placentas from PE and normal pregnancies. We found that HSP20 was reversely related to the apoptosis rate and the levels of proapoptotic proteins. Moreover, we identified that HSP20 could suppress the proliferation and apoptosis of trophoblast cells, turning them into a more invasive phenotype. Additionally, H₂O₂-induced oxidative stress was significantly alleviated, and several key proteins on the Akt signaling pathway were upregulated in HSP20-overexpressing trophoblast cells. These findings strongly suggested that HSP20 might play a role in the remodeling of spiral arteries through affecting the invasiveness of extravillous trophoblast cells via Akt signaling pathway, and the dysregulation of it might contribute to the pathophysiology of PE.

Integrated analysis of DNA methylation profiling and gene expression profiling identifies novel markers in lung cancer in Xuanwei, China

BACKGROUND

Aberrant DNA methylation occurs frequently in cancer. The aim of this study was to identify novel methylation markers in lung cancer in Xuanwei, China, through integrated genome-wide DNA methylation and gene expression studies.

METHODS

Differentially methylated regions (DMRs) and differentially expressed genes (DEGs) were detected on 10 paired lung cancer tissues and noncancerous lung tissues by methylated DNA immunoprecipitation combined with microarray (MeDIP-chip) and gene expression microarray analyses, respectively. Integrated analysis of DMRs and DEGs was performed to screen out candidate methylation-related genes. Both methylation and expression changes of the candidate genes were further validated and analyzed.

RESULTS

Compared with normal lung tissues, lung cancer tissues expressed a total of 6,899 DMRs, including 5,788 hypermethylated regions and 1,111 hypomethylated regions. Integrated analysis of DMRs and DEGs identified 45 tumor-specific candidate genes: 38 genes whose DMRs were hypermethylated and expression was downregulated, and 7 genes whose DMRs were hypomethylated and expression was upregulated. The methylation and expression validation results identified 4 candidate genes (STXBP6, BCL6B, FZD10, and HSPB6) that were significantly hypermethylated and downregulated in most of the tumor tissues compared with the noncancerous lung tissues.

CONCLUSIONS

This integrated analysis of genome-wide DNA methylation and gene expression in lung cancer in Xuanwei revealed several genes regulated by promoter methylation that have not been described in lung cancer before. These results provide new insight into the carcinogenesis of lung cancer in Xuanwei and represent promising new diagnostic and therapeutic targets.

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.

Small heat shock proteins in ageing and age-related diseases

Small heat shock proteins (sHSPs) are gatekeepers of cellular homeostasis across species, preserving proteome integrity under stressful conditions. Nonetheless, recent evidence suggests that sHSPs are more than molecular chaperones with merely auxiliary role. In contrast, sHSPs have emerged as central lifespan determinants, and their malfunction has been associated with the manifestation of neurological disorders, cardiovascular disease and cancer malignancies. In this review, we focus on the role of sHSPs in ageing and age-associated diseases and highlight the most prominent paradigms, where impairment of sHSP function has been implicated in human pathology.

SUMOylation of HSP27 by small ubiquitin-like modifier 2/3 promotes proliferation and invasion of hepatocellular carcinoma cells

Primary hepatocellular carcinoma (PHC) is a major health problem worldwide and is one of the 10 most commonly diagnosed cancers in China. Heat shock protein 27 (HSP27) were found to be overexpressed in a wide range of malignancies including PHC, however, post-translational modification of HSP27 still needs exploration in PHC. Recently, SUMOylation, an important post-translational modification associating with the development of many kinds of cancers has been intensively studied. In the current study, mRNA and protein level of HSP27 in archived tumor samples representing various pathological characteristics of PHC were examined, and modification of HSP27 by SUMO2/3 was investigated. HSP27 were expressed abundantly in patients' tumor tissues, and found to be associated with pathological progression. Besides, HSP27 was also elevated significantly in liver cancer cell lines Huh7 and HepG2 compared with human hepatocyte cells L02. Furthermore, knockdown of HSP27 was found to be associated with the decreased proliferation and invasion ability in Huh7 and HepG2 cells. Immunofluorescence assay showed that HSP27 and SUMO2/3 were co-localized in the subcellular, and co-immunoprecipitation verified the interaction between HSP27 and SUMO2/3. Overexpression of SUMO2/3 upregulated the HSP27 protein level and promotes Huh7 and HepG2 cell proliferation and invasion, and vice versa when the SUMO2/3 was knockdown. Taken together, increased protein level of HSP27 through SUMO2/3-mediated SUMOylation plays crucial roles in the progression of PHC, and this finding may shed light on developing potential therapeutic targets for PHC.