Hsp27 protects adenocarcinoma cells from UV-induced apoptosis by Akt and p21-dependent pathways of survival

Comprehensive transcriptional analysis of pig facial skin development

Background

Skin development is a complex process that is influenced by many factors. Pig skin is used as an ideal material for xenografts because it is more anatomically and physiologically similar to human skin. It has been shown that the skin development of different pig breeds is different, and some Chinese pig breeds have the characteristics of skin thickness and facial skin folds, but the specific regulatory mechanism of this skin development is not yet clear.

Methods

In this study, the facial skin of Chenghua sows in the four developmental stages of postnatal Day 3 (D3) , Day 90 (D90) , Day 180 (D180), and Year 3 (Y3) were used as experimental materials, and RNA sequencing (RNA-seq) analysis was used to explore the changes in RNA expression in skin development at the four developmental stages, determine the differentially expressed messenger RNAs (mRNAs), long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), and perform functional analysis of related genes by Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses.

Results

A pairwise comparison of the four developmental stages identified several differentially expressed genes (DEGs) and found that the number of differentially expressed RNAs (DE RNAs) increased with increasing developmental time intervals. Elastin (ELN) is an important component of the skin. Its content affects the relaxation of the epidermis and dermal connection, and its expression is continuously downregulated during the four developmental stages. The functions of DEGs at different developmental stages were examined by performing GO and KEGG analyses, and the GO terms and enrichment pathways of mRNAs, lncRNAs, miRNAs, and circRNAs highly overlapped, among which the PPAR signaling pathway, a classical pathway for skin development, was enriched by DEGs of D3 vs. D180, D90 vs. D180 and D180 vs. Y3. In addition, we constructed lncRNA-miRNA-mRNA and circRNA-miRNA interaction networks and found genes that may be associated with skin development, but their interactions need further study.

Conclusions

We identified a number of genes associated with skin development, performed functional analyses on some important DEGs and constructed interaction networks that facilitate further studies of skin development.

HSPB2 facilitates neural regeneration through autophagy for sensorimotor recovery after traumatic brain injury

Autophagy is a promising target for promoting neural regeneration, which is essential for sensorimotor recovery following traumatic brain injury (TBI). Whether neuronal heat shock protein B2 (HSPB2), a small molecular heat shock protein, reduces injury and promotes recovery following TBI remains unclear. In this study, we demonstrated that HSPB2 was significantly increased in the neurons of a TBI mouse model, patients, and primary neuron cultures subjected to oxygen/glucose deprivation and reperfusion treatment. Upon creating a tamoxifen-induced neuron-specific HSPB2 overexpression transgenic mouse model, we found that elevated HSPB2 levels promoted long-term sensorimotor recovery and alleviated tissue loss after TBI. We also demonstrated that HSPB2 enhanced white matter structural and functional integrity, promoted central nervous system (CNS) plasticity, and accelerated long-term neural remodeling. Moreover, we found that autophagy occurred around injured brain tissues in patients, and the pro-regenerative effects of HSPB2 relied on its autophagy-promoting function. Mechanistically, HSPB2 may regulate autophagy possibly by forming the HSPB2/BCL2-associated athanogene 3/sequestosome-1 complex to facilitate the clearance of erroneously accumulated proteins in the axons. Treatment with the autophagy inhibitor chloroquine during the acute stage or delayed induction of HSPB2 remarkably impeded HSPB2's long-term reparative function, indicating the importance of acute-stage autophagy in long-term neuro-regeneration. Our findings highlight the beneficial role of HSPB2 in neuro-regeneration and functional recovery following acute CNS injury, thereby emphasizing the therapeutic potential of autophagy regulation for enhancing neuro-regeneration.

Peelable Microneedle Patches Deliver Fibroblast Growth Factors to Repair Skin Photoaging Damage

Rationale: UV light deeply penetrates the dermis, leading to inflammation and cell death with prolonged exposure. This is a major contributor to skin photoaging. In the pharmaceutical field, fibroblast growth factors (FGFs) have gained popularity for enhancing skin quality as they facilitate tissue remodeling and re-epithelization. Nonetheless, their effectiveness is significantly hindered by limited absorption. Methods: We have successfully created a dissolving microneedle (MN) patch that contains hyaluronic acid (HA) loaded with FGF-2 and FGF-21. This patch aims to improve the therapeutic efficiency of these growth factors while providing a simple administration method. We determined the performance of this patch in an animal model of skin photoaging. Results: The FGF-2/FGF-21-loaded MN (FGF-2/FGF-21 MN) patch demonstrated a consistent structure and suitable mechanical properties, allowing for easy insertion and penetration into mouse skin. Within 10 minutes of application, the patch released approximately 38.50 ± 13.38% of the loaded drug. Notably, the FGF-2/FGF-21 MNs exhibited significant improvements in UV-induced acute skin inflammation and reduced mouse skin wrinkles within a span of two weeks. Furthermore, the positive effects continued to enhance over a four-week treatment period. Conclusion: The proposed HA-based peelable MN patch provides an efficient approach for transdermal drug delivery, providing a promising method for improved therapeutic outcomes.

Immunomorphological Patterns of Chaperone System Components in Rare Thyroid Tumors with Promise as Biomarkers for Differential Diagnosis and Providing Clues on Molecular Mechanisms of Carcinogenesis

Hurthle cell (HC), anaplastic (AC), and medullary (MC) carcinomas are low frequency thyroid tumors that pose several challenges for physicians and pathologists due to the scarcity of cases, information, and histopathological images, especially in the many areas around the world in which sophisticated molecular and genetic diagnostic facilities are unavailable. It is, therefore, cogent to provide tools for microscopists to achieve accurate diagnosis, such as histopathological images with reliable biomarkers, which can help them to reach a differential diagnosis. We are investigating whether components of the chaperone system (CS), such as the molecular chaperones, can be considered dependable biomarkers, whose levels and distribution inside and outside cells in the tumor tissue could present a distinctive histopathological pattern for each tumor type. Here, we report data on the chaperones Hsp27, Hsp60, and Hsp90. They presented quantitative levels and distribution patterns that were different for each tumor and differed from those of a benign thyroid pathology, goiter (BG). Therefore, the reported methodology can be beneficial when the microscopist must differentiate between HC, AC, MC, and BG.

Pathobiological functions and clinical implications of annexin dysregulation in human cancers

Annexins are an extensive superfamily of structurally related calcium- and phospholipid-binding proteins, largely conserved and widely distributed among species. Twelve human annexins have been identified, referred to as Annexin A1-13 (A12 remains as of yet unassigned), whose genes are spread throughout the genome on eight different chromosomes. According to their distinct tissue distribution and subcellular localization, annexins have been functionally implicated in a variety of biological processes relevant to both physiological and pathological conditions. Dysregulation of annexin expression patterns and functions has been revealed as a common feature in multiple cancers, thereby emerging as potential biomarkers and molecular targets for clinical application. Nevertheless, translation of this knowledge to the clinic requires in-depth functional and mechanistic characterization of dysregulated annexins for each individual cancer type, since each protein exhibits varying expression levels and phenotypic specificity depending on the tumor types. This review specifically and thoroughly examines the current knowledge on annexin dysfunctions in carcinogenesis. Hence, available data on expression levels, mechanism of action and pathophysiological effects of Annexin A1-13 among different cancers will be dissected, also further discussing future perspectives for potential applications as biomarkers for early diagnosis, prognosis and molecular-targeted therapies. Special attention is devoted to head and neck cancers (HNC), a complex and heterogeneous group of aggressive malignancies, often lately diagnosed, with high mortality, and scarce therapeutic options.

Activation of the HSP27-AKT axis contributes to gefitinib resistance in non-small cell lung cancer cells independent of EGFR mutations

PURPOSE

Although epidermal growth factor receptor (EGFR)-activating mutations in non-small cell lung cancer (NSCLC) usually show sensitivity to first-generation EGFR-tyrosine kinase inhibitors (TKIs), most patients relapse because of drug resistance. Heat shock protein 27 (HSP27) has been reported to be involved in the resistance of EGFR-TKIs, although the underlying mechanism is unclear. Here, we explore the mechanisms of HSP27-mediated EGFR TKI resistance and propose novel therapeutic strategies.

METHODS

To determine the mechanism of HSP27 associated gefitinib resistance, differences were assessed using gefitinib-sensitive and -resistant NSCLC cell lines. In vivo xenograft experiments were conducted to elucidate the combinatorial effects of J2, a small molecule HSP27 inhibitor, and gefitinib. Analyses of human NSCLC tissues and PDX tissues were also used for comparison of HSP27 and phosphorylated AKT expression.

RESULTS

Large-scale cohort analysis of NSCLC cases revealed that HSP27 expression correlated well with the incidence of EGFR mutations and affected patient survival. Increased pAKT and HSP27 was observed in gefitinib-resistant cells compared with gefitinib-sensitive cells. Moreover, increased phosphorylation of HSP27 by gefitinib augmented its protein stability and potentiated its binding activity with pAKT, which resulted in increased gefitinib resistance. However, in gefitinib-sensitive cells, stronger binding activity between EGFR and HSP27 was observed. Moreover, these phenomena occurred regardless of EGFR mutation including secondary mutations, such as T790M. AKT knockdown switched HSP27-pAKT binding to HSP27-EGFR, which promoted gefitinib sensitivity in gefitinib-resistant cells. Functional inhibition of HSP27 yielded sensitization to gefitinib in gefitinib-resistant cells by inhibiting the interaction between HSP27 and pAKT.

CONCLUSIONS

Our results indicate that combination of EGFR-TKIs with HSP27 inhibitors may represent a good strategy to overcome resistance to EGFR-TKIs, especially in cancers exhibiting AKT pathway activation.

Identification, expression analysis and functional verification of two genes encoding small heat shock proteins in the western flower thrips, Frankliniella occidentalis (Pergande)

Small heat shock proteins (sHSPs) help prevent the irreversible aggregation of denatured proteins that occurs in response to organismal stress. In this study, we identified two intron-free genes encoding sHSPs from Frankliniella occidentalis; these were designated FoHSP11.6 and FoHSP28.0 and belonged to an atypical and typical sHSP family, respectively. Both FoHSPs were transcribed in all developmental stages of F. occidentalis with the highest expression levels in pupae and adults and greater expression in males than females. Although the FoHSPs had different temperature-induced expression profiles, they were generally induced by both low and high temperatures and reached maximal expression levels after 0.5-1 h of temperature stress. The FoHSPs expression levels in pupae were induced by drought and high humidity, and higher expression levels were correlated with lower survival rates. The thermotolerance of F. occidentalis decreased when theFoHSPs were silenced by RNA interference. Our results show that FoHSP11.6 and FoHSP28.0 are involved in the response to temperature and drought and may also function in growth and development of F. occidentalis.

Characterization and functional analysis of Cshsp19.0 encoding a small heat shock protein in Chilo suppressalis (Walker)

Small heat shock proteins (sHSPs) function as ATP-independent chaperones that preserve cellular proteostasis under stressful conditions. In this study, Cshsp19.0, which encodes a new small heat shock protein, was isolated and characterized from Chilo suppressalis (Walker) to better understand the contribution of sHSPs to insect development and stress tolerance. The full-length Cshsp19.0 cDNA was 697 bp and encoded a 19.0 kDa protein with an isoelectric point of 5.95. Phylogenetic analysis and amino acid alignments indicated that Cshsp19.0 is a member of the sHSP family. Cshsp19.0 was expressed at maximal levels in foreguts and showed the least amount of expression in fat bodies. Expression analysis in different developmental stages of C. suppressalis revealed that Cshsp19.0 was most highly expressed in 1st instar larvae. Furthermore, Cshsp19.0 was upregulated when insects were exposed to heat and cold stress for a 2-h period. There were significant differences in the male and female pupae in response to humidity; Cshsp19.0 expression increased in male pupae as RH increased, whereas the inverse pattern was observed in female pupae. Larvae exhibited a lower rate of survival when Cshsp19.0 was silenced by a nanomaterial-promoted RNAi method. The results confirm that Cshsp19.0 functions to increase environmental stress tolerance and regulates physiological activities in C. suppressalis.

HSP27 role in cardioprotection by modulating chemotherapeutic doxorubicin-induced cell death

The common phenomenon expected from any anti-cancer drug in use is to kill the cancer cells without any side effects to non-malignant cells. Doxorubicin is an anthracycline derivative anti-cancer drug active over different types of cancers with anti-cancer activity but attributed to unintended cytotoxicity and genotoxicity triggering mitogenic signals inducing apoptosis. Administration of doxorubicin tends to both acute and chronic toxicity resulting in cardiomyopathy (left ventricular dysfunction) and congestive heart failure (CHF). Cardiotoxicity is prevented through administration of different cardioprotectants along with the drug. This review elaborates on mechanism of drug-mediated cardiotoxicity and attenuation principle by different cardioprotectants, with a focus on Hsp27 as cardioprotectant by prevention of drug-induced oxidative stress, cell survival pathways with suppression of intrinsic cell death. In conclusion, Hsp27 may offer an exciting/alternating cardioprotectant, with a wider study being need of the hour, specifically on primary cell line and animal models in conforming its cardioprotectant behaviour.

Mild stress culture conditions promote neurite outgrowth of retinal explants from postnatal mice

The axons of retinal ganglion cells (RGCs) in adult mammals fail to regenerate after injury. It has been suggested that some extrinsic factors, such as neural activity, may promote the regeneration process. The present study tested the hypothesis that environmental stress such as slightly elevated osmolarity and temperature can enhance neural activity and thus promote axon regeneration of RGCs in postnatal mice. Retinal explants from P9-11 mice were cultured for 5 days to study the capacity of RGC neurite outgrowth. The neural activity of retinal explants in these two stress conditions was examined using the multi-electrode array. We found that RGC neurite outgrowth from P9-P11 mouse explants was significantly enhanced when the concentration of the culture medium was increased by 1.25 fold, but not when increased by 1.5 fold. Similarly, retinal explants from P9-P11 mice grew longer neurites when the overall temperature was increased from 35 °C to 38 °C, 40 °C or 42 °C for one hour each day, but not when they were kept at 40 °C or 42 °C constantly for five days. We further showed that there was increased neural activity during these two mild stress conditions. It was found that short-term 42 °C heat stress increased the expression of heat shock proteins 27 and 70 in postnatal retinas and they were RGC neural activity dependent. The present study thus provides insights into the cellular mechanism of retinal axon regeneration under the mild stress conditions.

Imaging of metabolic activity adaptations to UV stress, drugs and differentiation at cellular resolution in skin and skin equivalents - Implications for oxidative UV damage

The epidermis is a multi-layered epithelium that consists mainly of keratinocytes which proliferate in its basal layer and then differentiate to form the stratum corneum, the skin's ultimate barrier to the environment. During differentiation keratinocyte function, chemical composition, physical properties, metabolism and secretion are profoundly changed. Extrinsic or intrinsic stressors, like ultraviolet (UV) radiation thus may differently affect the epidermal keratinocytes, depending on differentiation stage. Exposure to UV elicits the DNA damage responses, activation of pathways which detoxify or repair damage or induction of programmed cell death when the damage was irreparable. Recently, rapid diversion of glucose flux into the pentose phosphate pathway (PPP) was discovered as additional mechanism by which cells rapidly generate reduction equivalents and precursors for nucleotides - both being in demand after UV damage. There is however little known about the correlation of such metabolic activity with differentiation state, cell damage and tissue localization of epidermal cells. We developed a method to correlate the activity of G6PD, the first and rate-limiting enzyme of this metabolic UV response, at cellular resolution to cell type, differentiation state, and cell damage in human skin and in organotypic reconstructed epidermis. We thereby could verify rapid activation of G6PD as an immediate UVB response not only in basal but also in differentiating epidermal keratinocytes and found increased activity in cells which initiated DNA damage responses. When keratinocytes had been UVB irradiated before organotypic culture, their distribution within the skin equivalent was abnormal and the G6PD activity was reduced compared to neighboring cells. Finally, we found that the anti-diabetic and potential anti-aging drug metformin strongly induced G6PD activity throughout reconstructed epidermis. Activation of the protective pentose phosphate pathway may be useful to enhance the skin's antioxidant defense systems and DNA damage repair capacity on demand.

Interference of Hsp27 Results in Apoptosis Induced by Photodamage via Regulation of Subcellular Localization of p21 in Immortalized Human Keratinocytes

BACKGROUND Owing to the increased incidence of photodermatosis caused by ultraviolet light in recent years, it is necessary to clarify the mechanisms potential photodamage to the skin and reveal possible therapeutic targets. Heat shock protein 27 (Hsp27) is well known for suppressing apoptosis. The aim of present study was to elucidate possible photoprotective mechanism between Hsp27 and p21 on ultraviolet B (UVB)-induced photodamage. MATERIAL AND METHODS The Hsp27 gene was interfered to assess the expression of its downstream effectors, cell apoptosis, and cell proliferation ability. The cell apoptosis was tested using flow cytometry method. The cell proliferation ability was tested using Cell Counting Kit-8 (CCK-8) assay. The expression of protein was tested using western-blotting method. The expression of mRNA was detected using quantitative reverse transcription polymerase chain reaction (qRT-PCR). The subcellular localization was elucidated using immunofluorescence. RESULTS Hsp27 knockdown decreased cell viability and increased the incidence of UVB-induced apoptosis. Compared with control group, activation of phosphorylated-Akt (p-Akt)-dependent pathway resulted in the nuclear accumulation of p21 and suppression of cell proliferation, while promoting apoptosis in Hsp27 knockdown group. In addition, Hsp27 knockdown increased p53 expression and the Bax: Bcl-2 ratio, which further accelerated the apoptotic process. CONCLUSIONS These findings complemented the mechanism of skin photodamage and demonstrated the photoprotective mechanisms of Hsp27 in HaCaT cells, which might implicate a potential therapeutic target of photodamage and photodermatosis.

Flavonoid-alkylphospholipid conjugates elicit dual inhibition of cancer cell growth and lipid accumulation

Cancer development is often associated with lipid metabolic reprogramming, including aberrant lipid accumulation. We create novel paradigms endowed with dual functions of anticancer activity and inhibition of lipid accumulation by conjugating the natural product quercetin and synthetic alkylphospholipid drugs, and harnessing the biomedical effects of both. These conjugates offer fresh perspectives in the search for anticancer candidates.

High metabolic rate and stem cell characteristics of esophageal cancer stem-like cells depend on the Hsp27-AKT-HK2 pathway

Tumor progression with chemoresistance and local recurrence is commonly happened during treatment of esophageal squamous cell carcinoma (ESCC). Cancer stem cells (CSC) may respond for tumor progression. However, there are few reports regarding metabolism of esophageal CSCs with clinical correlation. In this work, we demonstrated that ESCC cell lines in spheroid culture display CSC phenotypes, including increased ALDH activity, chemoresistance and tumor initiation, which are dependent on Hsp27 activation. Esophageal CSCs also exhibit reprogrammed metabolic features particularly higher glycolysis and oxidative phosphorylation, which are regulated via the Hsp27-AKT-HK2 pathway. Moreover, HK2 is required for maintenance of CSC phenotypes. Inhibition of CSC metabolism reduces cell growth and tumor formation. Clinically, patients who underwent surgical resection for esophageal cancer, and displayed overexpression of both Hsp27 and HK2, had the worst prognosis of all expression types. In conclusion, stem cells features and aberrant metabolic reprogramming of esophageal CSCs depend on the Hsp27-AKT-HK2 pathway. Targeting Hsp27 and HK2 could be novel therapeutic strategy for treating esophageal cancer and warrants further investigation.

Characterization and functional analysis of hsp18.3 gene in the red flour beetle, Tribolium castaneum

Small heat shock proteins (sHSPs) are diverse and mainly function as molecular chaperones to protect organisms and cells from various stresses. In this study, hsp18.3, one Tribolium castaneum species-specific shsp, has been identified. Quantitative real-time polymerase chain reaction illustrated that Tchsp18.3 is expressed in all developmental stages, and is highly expressed at early pupal and late adult stages, while it is highly expressed in ovary and fat body at the adult period. Moreover, it was up-regulated 4532 ± 396-fold in response to enhanced heat stress but not to cold stress; meanwhile the lifespan of adults in ds-Tchsp18.3 group reduced by 15.8% from control group under starvation. Laval RNA interference (RNAi) of Tchsp18.3 caused 86.1% ± 4.5% arrested pupal eclosion and revealed that Tchsp18.3 played an important role in insect development. In addition, parental RNAi of Tchsp18.3 reduced the oviposition amount by 94.7%. These results suggest that Tchsp18.3 is not only essential for the resistance to heat and starvation stress, but also is critical for normal development and reproduction in T. castaneum.

S1P promotes migration, differentiation and immune regulatory activity in amniotic-fluid-derived stem cells

Stem cells have high potential for cell therapy in regenerative medicine. We previously isolated stem cell types from human amniotic fluid, derived from prenatal amniocentesis. One type, characterized by a fast doubling time, was designated as fast human amniotic stem cells (fHASCs). These cells exhibited high differentiation potential and immunoregulatory properties. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid metabolite that influences stem-cell pluripotency, differentiation, mobility, and regulates immune functions. In this study, we investigated the influence of S1P on fHASC migration, proliferation, differentiation and immune regulatory functions. We found that fHASC stimulation with S1P potentiated their migratory and proliferative activity in vitro. Notably, short fHASC exposure to S1P enhanced their differentiation towards multiple lineages, including adipocytes, osteocytes and endothelial cells, an effect that was associated with downregulation of the main transcription factors involved in the maintenance of a stem-cell undifferentiated state. A specific crosstalk between S1P and tumor growth factor β1 (TGF-β1) has recently been demonstrated. We found that fHASC exposure to S1P in combination with TGF-β1 promoted the expression of the immune regulatory pathway of indoleamine 2,3-dioxygenase 1 (IDO1). In addition, human peripheral blood mononuclear cells, co-cultured with fHASCs treated with S1P and TGF-β1, expanded regulatory T-cells, via a mechanism requiring IDO1. Overall, this study demonstrates that S1P potentiates several properties in fHASCs, an effect that may be critical for exploiting the therapeutic potential of fHASCs and might explain the specific effects of S1P on stem cells during pregnancy.

Discovering a Reliable Heat-Shock Factor-1 Inhibitor to Treat Human Cancers: Potential Opportunity for Phytochemists

Heat-shock factor-1 (HSF-1) is an important transcription factor that regulates pathogenesis of many human diseases through its extensive transcriptional regulation. Especially, it shows pleiotropic effects in human cancer, and hence it has recently received increased attention of cancer researchers. After myriad investigations on HSF-1, the field has advanced to the phase where there is consensus that finding a potent and selective pharmacological inhibitor for this transcription factor will be a major break-through in the treatment of various human cancers. Presently, all reported inhibitors have their limitations, made evident at different stages of clinical trials. This brief account summarizes the advances with tested natural products as HSF-1 inhibitors and highlights the necessity of phytochemistry in this endeavor of discovering a potent pharmacological HSF-1 inhibitor.

Annexin A2-mediated cancer progression and therapeutic resistance in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a head and neck cancer with poor clinical outcomes and insufficient treatments in Southeast Asian populations. Although concurrent chemoradiotherapy has improved recovery rates of patients, poor overall survival and low efficacy are still critical problems. To improve the therapeutic efficacy, we focused on a tumor-associated protein called Annexin A2 (ANXA2). This review summarizes the mechanisms by which ANXA2 promotes cancer progression (e.g., proliferation, migration, the epithelial-mesenchymal transition, invasion, and cancer stem cell formation) and therapeutic resistance (e.g., radiotherapy, chemotherapy, and immunotherapy). These mechanisms gave us a deeper understanding of the molecular aspects of cancer progression, and further provided us with a great opportunity to overcome therapeutic resistance of NPC and other cancers with high ANXA2 expression by developing this prospective ANXA2-targeted therapy.

Dihydroartemisinin sensitizes Lewis lung carcinoma cells to carboplatin therapy via p38 mitogen-activated protein kinase activation

Dihydroartemisinin (DHA), a semi-synthetic derivative of artemisinin isolated from the traditional Chinese herb Artemisia annua, is an effective novel antimalarial agent. Studies have suggested that it also exhibits anticancer effects when administered alone or in combination with conventional chemotherapeutic agents. The present study investigated the therapeutic effect of DHA combined with carboplatin (CBP) on Lewis lung carcinoma (LLC) cells and the possible underlying molecular mechanisms. MTT and clonogenic assays demonstrated that the proliferation activity of LLC cells was inhibited in a dose-dependent manner by DHA combined with CBP. In addition, flow cytometry analysis revealed that cell cycle arrest was induced at the G₀/G₁ phase and apoptosis was induced following treatment with the combination. When administered in combination with CBP, DHA exhibited more effective anticancer activity compared with DHA or CBP used alone, via increased apoptosis. Following treatment with DHA with or without CBP, the expression of phosphorylated-p38 mitogen-activated protein kinase (MAPK), which can be inhibited with the selective inhibitor SB202190, was detected by western blotting. To summarize, the results of the present study indicated that DHA may sensitize LLC cells to CBP therapy via the activation of p38MAPK, which suggests that a combined treatment of DHA and CBP may be a potential novel therapeutic schedule for lung adenocarcinoma.

The clinicopathological and prognostic value of HSP27 in hepatocellular carcinoma: a systematic review and meta-analysis

Background

In the recent past, there is increasing evidence demonstrating that HSP27 plays a key role in tumor progression. However, the relationship between HSP27 expression and the clinicopathological features of hepatocellular carcinoma (HCC), as well as its prognostic value in HCC patients remain controversial. Accordingly, we conducted a meta-analysis to assess the correlation between HSP27 expression and HCC, and determine the prognostic value of HSP27 in HCC.

Methods

The data included clinicopathological features and survival information extracted from the published literature in the databases PubMed, EMBASE, Cochrane Library, Web of Science, CNKI, and Wan Fang. The pooled odds ratios and hazard ratios with 95% CIs were calculated using Forest plot analysis.

Results

The meta-analysis results indicated that the positive HSP27 expression was significantly correlated with HCC incidence, tumor differentiation, and α-fetoprotein level in patients with HCC. However, the expression of HSP27 was not associated with metastasis, hepatitis B virus surface antigen, gender, tumor size, TNM stage, and vascular invasion. Additionally, HSP27 expression indicated a poor overall survival rate, but it was not related to disease-free survival rate.

Conclusion

This meta-analysis revealed that HSP27 may play a key role in the development of HCC and could be a reliable biomarker for the prognosis of patients with HCC. However, additional high-quality research is needed to support the results.

Vascular endothelial growth receptor 1 acts as a stress-associated protein in the therapeutic response to thalidomide

Thalidomide (THD) exhibits antitumor effects in several types of cancer. However, the failure of THD to inhibit tumor growth has also been observed in a number of murine models in vivo. The mechanism involved in the therapeutic failure of THD remains unclear. The present study demonstrated that, accompanied by growth-arresting and apoptosis-inducing effects (P<0.05), THD upregulated vascular endothelial growth factor receptor 1 (VEGFR1) expression levels in CT26 murine colorectal carcinoma cell lines. This in vitro phenomenon was also observed in various other cell lines, including human umbilical vein endothelial cells, SW480, SW620 and HCT116. Reactive oxygen species (ROS) levels were increased compared with those in the untreated control when cells were exposed to THD (P<0.05). Furthermore, results suggested that ROS suppression may have provoked the induction of VEGFR1 expression to some extent. In addition, the results revealed that THD failed to inhibit CT26 tumor growth in vivo and the expression of VEGFR1 protein was elevated by THD treatment compared with the control group in the murine colorectal tumor model (P<0.05). The results of further experiments suggested that VEGFR1 was elevated in response to various stress-associated situations, including chemotherapy, radiotherapy and thermotherapy, which indicate that it may act as a stress-associated protein. The present findings provide a foundation for the future study of VEGFR1-targeted therapy to enhance the efficacy of current therapies.

CRISPR-ON-Mediated KLF4 overexpression inhibits the proliferation, migration and invasion of urothelial bladder cancer in vitro and in vivo

Kruppel like factor 4 (KLF4), a transcription factor associated with carcinogenesis and tumor progression, plays an important role in various malignancies. In the present study, we utilized the CRISPR-ON system to upregulate KLF4 expression level and subsequently investigated the effect and mechanism of KLF4 in the carcinogenesis and progression of urothelial bladder cancer (UBC). Immunohistochemistry (IHC) and quantitative RT-PCR (qRT-PCR) were used to evaluate the expression of KLF4. The CpG methylation status of the promoter region was analyzed using bisulfite-sequencing PCR (BSP). CRISPR-ON system comprised sgRNA and dCas9 protein combined with a transcriptional activation domain. The cell proliferation and cell cycle were assessed by CCK-8 assay, flow cytometry and colony formation assay. The cell motility ability was evaluated using trans-well assay. In vivo tumorigenesis assay and lung metastasis model were also performed. The KLF4 expression was significantly downregulated in UBC tissues. The high CpG methylation status in the promoter of KLF4 was confirmed using BSP. KLF4 overexpression was successfully achieved via CRISPR-ON system, which inhibited the proliferation and induced G1-phase arrest in T24 cells through the regulation of AKT/p21 signal. Furthermore, enforced expression of KLF4 also abrogated the migration and invasion of T24 cells by suppressing EMT progression. Finally, in vivo models indicated that the upregulation of KLF4 could inhibit tumorigenesis and lung metastasis in nude mice. In conclusion, KLF4 overexpression mediated by CRISPR-ON inhibits tumorigenesis and EMT progression in UBC cells, representing a potential therapeutic target, and CRISPR-ON system could be a therapeutic strategy for UBC in the future.

HSPB1 facilitates ERK-mediated phosphorylation and degradation of BIM to attenuate endoplasmic reticulum stress-induced apoptosis

BIM, a pro-apoptotic BH3-only protein, is a key regulator of the intrinsic (or mitochondrial) apoptosis pathway. Here, we show that BIM induction by endoplasmic reticulum (ER) stress is suppressed in rat PC12 cells overexpressing heat shock protein B1 (HSPB1 or HSP27) and that this is due to enhanced proteasomal degradation of BIM. HSPB1 and BIM form a complex that immunoprecipitates with p-ERK1/2. We found that HSPB1-mediated proteasomal degradation of BIM is dependent on MEK-ERK signaling. Other studies have shown that several missense mutations in HSPB1 cause the peripheral neuropathy, Charcot-Marie-Tooth (CMT) disease, which is associated with nerve degeneration. Here we show that cells overexpressing CMT-related HSPB1 mutants exhibited increased susceptibility to ER stress-induced cell death and high levels of BIM. These findings identify a novel function for HSPB1 as a negative regulator of BIM protein stability leading to protection against ER stress-induced apoptosis, a function that is absent in CMT-associated HSPB1 mutants.

Heat Shock Protein 27, a Novel Regulator of Transforming Growth Factor β Induced Resistance to Cisplatin in A549 Cell

Lung cancer is one of the major causes of cancer morbidity and mortality around the world, and the resistance to cisplatin is a critical issue to chemotherapy in lung cancer patients. Transforming growth factor β (TGF-β) signal pathway abnormality is widely observed in drug resistance during lung cancer chemotherapy. Here, we investigated the effects of heat-shock protein 27 (HSP27) in the TGF-β-induced cisplatin resistance in lung cancer cell. In this study, our results indicated that the mRNA and protein expression of HSP27 were significantly increased in human lung cancer tissues. TGF-β induced the mRNA and protein expression of HSP27 in human lung cancer cell (A549). Treatment of TGF-β-induced cisplatin resistance in A549 cell through blocking the cisplatin-induced apoptosis and cell death, which characterized as the increasing of cell viability and decreasing of PARP and caspase3 cleavage in the cisplatin-treated cell. Knockdown of SMAD3 attenuated the TGF-β-induced HSP27 expression and restored the TGF-β-induced cisplatin resistance in A549 cell. Additionally, the knockdown of HSP27 blocked TGF-β-induced cisplatin resistance via decreasing cell viability and increasing cell apoptosis in A549 cell. These data therefore suggested that HSP27 is critical to lung cancer progression and TGF-β-induced cisplatin resistance in human lung cancer cell, and may provide an effective clinical strategy in lung cancer patients with resistance to chemotherapy.

Comparative proteomics-network analysis of proteins responsible for ursolic acid-induced cytotoxicity in colorectal cancer cells

Ursolic acid is a key active compound present in many medicinal herbs that have been widely used in traditional Chinese medicine for the clinical treatment of various cancers. However, the precise mechanisms of its antitumor activity have been poorly understood. To identify the cellular targets of ursolic acid, two-dimensional gel electrophoresis combined with mass spectrometry was performed in this study, which identified 15 proteins with significantly altered levels in protein expression. This demonstrated that ursolic acid-induced cytotoxicity in colorectal cancer cells involves dysregulation in protein folding, signal transduction, cell proliferation, cell cycle, and apoptosis. Corresponding protein regulation was also confirmed by Western blotting. Furthermore, the study of functional association between these 15 proteins revealed that 10 were closely related in a protein-protein interaction network, whereby the proteins either had a direct interaction with each other or were associated via only one intermediary protein. In this instance, the ATP5B/CALR/HSP90B1/HSPB1/HSPD1-signaling network was revealed as the predominant target which was associated with the majority of the observed protein-protein interactions. As a result, the identified targets may be useful in explaining the anticancer mechanisms of ursolic acid and as potential targets for colorectal cancer therapy.

HSP27 Knockdown Increases Cytoplasmic p21 and Cisplatin Sensitivity in Ovarian Carcinoma Cells

Drug resistance is the leading cause of chemotherapy failure in the treatment of ovarian cancer. So far, little is known about the mechanism of chemoresistance in ovarian cancer. In this study, we explored the mechanism that HSP27 was involved in cisplatin resistance of ovarian cancer both in vitro and clinically. HSP27 protein was found to be upregulated and expressed in cisplatin-resistant ovarian cancer cell line C13*, and HSP27 siRNA transfection reversed the chemoresistance of C13*. We found that HSP27 exerted its chemoresistant role by inhibiting p21 transferring from the nucleus to the plasma through the activation of phosphorylated-Akt pathway. These findings have implications for clinical trials aimed at a potential therapeutic target for ovarian tumors that are refractory to conventional treatment.

Targeting annexin A2 reduces tumorigenesis and therapeutic resistance of nasopharyngeal carcinoma

The expression of annexin A2 (ANXA2) in nasopharyngeal carcinoma (NPC) cells induces the immunosuppressive response in dendritic cells; however, the oncogenic effect and clinical significance of ANXA2 have not been fully investigated in NPC cells. Immunohistochemical staining for ANXA2 was performed in 61 patients and the association with clinicopathological status was determined. Short hairpin (sh)RNA knockdown of ANXA2 was used to examine cellular effects of ANXA2, by investigating alterations in cell proliferation, migration, invasion, adhesion, tube-formation assay, and chemo- and radiosensitivity assays were performed. RT-qPCR, Western blotting, and immunofluorescence were applied to determine molecular expression levels. Clinical association studies showed that the expression of ANXA2 was significantly correlated with metastasis (p = 0.0326) and poor survival (p = 0.0256). Silencing of ANXA2 suppressed the abilities of cell proliferation, adhesion, migration, invasion, and vascular formation in NPC cell. ANXA2 up-regulated epithelial-mesenchymal transition associated signal proteins. Moreover, ANXA2 reduced sensitivities to irradiation and chemotherapeutic drugs. These results define ANXA2 as a novel prognostic factor for malignant processes, and it can serve as a molecular target of therapeutic interventions for NPC.

Heat shock protein 27 downstream of P38-PI3K/Akt signaling antagonizes melatonin-induced apoptosis of SGC-7901 gastric cancer cells

Background

Despite the fact that melatonin treatment shows some promise in gastric cancer, the molecular mechanisms of gastric cancer cells in response to melatonin remains to be determined.

Methods

The SGC-7901 gastric cancer cells were treated with different concentrations of melatonin for 24 and 48 h. Cell viability was determined by MTT assay, Hoechst 33258 staining and FACS analysis were used to detect apoptotic cells. The contents and activation of apoptosis-related proteins HSP27, Akt and P38 were evaluated by immunoblotting analysis. Then we treated SGC-7901 cells with HSP27-specific siRNA, PI3K inhibitor LY294002 or P38 inhibitor SB203580 to investigate the role of HSP27, Akt and P38 in the anti-apoptotic response of SGC-7901 cells to melatonin.

Results

Melatonin suppressed cell viability and stimulated apoptosis of gastric cancer SGC-7901 cells dose-dependently. Mechanistically, the observed apoptosis was accompanied by the melatonin-induced phosphorylation of HSP27. HSP27-specific siRNA transfection effectively reduced HSP27 phosphorylation and augmented melatonin-induced apoptosis, indicating that HSP27 is resistant to melatonin-induced apoptosis. Moreover, melatonin increased PI3K/Akt activation, LY294002 abrogated HSP27 activation and promoted cell apoptosis induced by melatonin. Furthermore, melatonin increased P38 activity, and P38 inhibitor SB203580 inhibited melatonin-induced PI3K/Akt, HSP27 activation and accelerated cell apoptosis.

Conclusion

In contrast to the well-established anti-cancer properties of melatonin, our study revealed clearly a distinguishable anti-apoptotic pathway induced by melatonin, that is, HSP27 plays a crucial role in apoptotic resistance in melatonin-treated gastric cancer cells, and its activation is most likely via the activation of P38/PI3K/Akt signaling.

Quantitative proteomic analysis shows differentially expressed HSPB1 in glioblastoma as a discriminating short from long survival factor and NOVA1 as a differentiation factor between low-grade astrocytoma and oligodendroglioma

Background

Gliomas account for more than 60 % of all primary central nervous system neoplasms. Low-grade gliomas display a tendency to progress to more malignant phenotypes and the most frequent and malignant gliomas are glioblastomas (GBM). Another type of glioma, oligodendroglioma originates from oligodendrocytes and glial precursor cells and represents 2–5 % of gliomas. The discrimination between these two types of glioma is actually controversial, thus, a molecular distinction is necessary for better diagnosis.

Methods

iTRAQ-based quantitative proteomic analysis was performed on non-neoplastic brain tissue, on astrocytoma grade II, glioblastoma with short and long survival and oligodendrogliomas.

Results

We found that expression of nucleophosmin (NPM1), glucose regulated protein 78 kDa (GRP78), nucleolin (NCL) and heat shock protein 90 kDa (HSP90B1) were increased, Raf kinase inhibitor protein (RKIP/PEBP1) was decreased in glioblastoma and they were associated with a network related to tumor progression. Expression level of heat shock protein 27 (HSPB1/HSP27) discriminated glioblastoma presenting short (6 ± 4 months, n = 4) and long survival (43 ± 15 months, n = 4) (p = 0.00045). Expression level of RNA binding protein nova 1 (NOVA1) differentiated low-grade oligodendroglioma and astrocytoma grade II (p = 0.0082). Validation were done by Western blot, qRT-PCR and immunohistochemistry in a larger casuistry.

Conclusion

Taken together, our quantitative proteomic analysis detected the molecular triad, NPM1, GRP78 and RKIP participating together with NCL and HSP27/HSPB1 in a network related to tumor progression. Additionally, two new important targets were uncovered: NOVA1 useful for diagnostic refinement differentiating astrocytoma from oligodendroglioma, and HSPB1/HSP27, as a predictive factor of poor prognosis for GBM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1473-9) contains supplementary material, which is available to authorized users.

Disruption of a regulatory loop between DUSP1 and p53 contributes to hepatocellular carcinoma development and progression

BACKGROUND & AIMS

Altered expression of dual specificity phosphatase 1 (DUSP1) is common in tumors including hepatocellular carcinoma (HCC), and is predictive of tumor progression and poor prognosis. However, the tumor suppressive role of DUSP1 has yet to be clearly elucidated.

METHODS

The molecular mechanisms of tumor suppression that were investigated were induction of apoptosis, cell cycle inhibition, and regulation of p53. Additionally, the antitumor effect of DUSP1 was assessed using a mouse model. Associated signaling pathways in HCC cells and tissues were examined.

RESULTS

Downregulation of DUSP1 expression was significantly correlated with poor differentiation (p<0.001) and advanced HCC stage (p=0.023). DUSP1 expression resulted in HCC suppression and longer survival (p=0.0002) in a xenoplant mice model. DUSP1 inhibited p38 MAPK phosphorylation and subsequently suppressed HSP27 activation, resulting in enhanced p53 phosphorylation at sites S15, S20, and S46 in HCC cells. Enhanced p53 activation induced the expression of target genes p21 and p27, which are linked to cell cycle arrest and apoptosis. Thus, DUSP1 was potentially linked to p53 activation via the p38 MAPK/HSP27 pathway. Wild-type but not mutant p53 transcriptionally upregulated DUSP1 via its DNA-binding domain. DUSP1 and p53 might collaborate to suppress tumors in hepatocarcinogenesis via a positive regulatory loop.

CONCLUSIONS

Our results revealed that disruption of a positive regulatory loop between DUSP1 and p53 promoted HCC development and progression, providing a rationale for a therapeutic agent that restores DUSP1 in HCC.

Small heat shock proteins: Role in cellular functions and pathology

Small heat shock proteins (sHsps) are conserved across species and are important in stress tolerance. Many sHsps exhibit chaperone-like activity in preventing aggregation of target proteins, keeping them in a folding-competent state and refolding them by themselves or in concert with other ATP-dependent chaperones. Mutations in human sHsps result in myopathies, neuropathies and cataract. Their expression is modulated in diseases such as Alzheimer's, Parkinson's and cancer. Their ability to bind Cu2+, and suppress generation of reactive oxygen species (ROS) may have implications in Cu2+-homeostasis and neurodegenerative diseases. Circulating αB-crystallin and Hsp27 in the plasma may exhibit immunomodulatory and anti-inflammatory functions. αB-crystallin and Hsp20 exhitbit anti-platelet aggregation: these beneficial effects indicate their use as potential therapeutic agents. sHsps have roles in differentiation, proteasomal degradation, autophagy and development. sHsps exhibit a robust anti-apoptotic property, involving several stages of mitochondrial-mediated, extrinsic apoptotic as well as pro-survival pathways. Dynamic N- and C-termini and oligomeric assemblies of αB-crystallin and Hsp27 are important factors for their functions. We propose a "dynamic partitioning hypothesis" for the promiscuous interactions and pleotropic functions exhibited by sHsps. Stress tolerance and anti-apoptotic properties of sHsps have both beneficial and deleterious consequences in human health and diseases. Conditional and targeted modulation of their expression and/or activity could be used as strategies in treating several human disorders. The review attempts to provide a critical overview of sHsps and their divergent roles in cellular processes particularly in the context of human health and disease.

p38MAPK activation mediates tumor necrosis factor-α-induced apoptosis in glioma cells

Gliomas are a type of heterogeneous primary central nervous system tumor, which arise from the glial cells; these types of tumor generally respond poorly to surgery, radiation and conventional chemotherapy. Tumor necrosis factor‑α (TNF‑α) has been suggested to produce an antitumor effect by binding to specific receptors on the tumor cell membrane to induce apoptosis. TNF‑α is known to activate a number of signaling pathways, including extracellular signal‑regulated protein kinase, c‑Jun N‑terminal kinase (JNK), p38 mitogen‑activated protein kinase (p38MAPK), nuclear factor‑κB and caspase cascades, depending on the cell type. However, the involvement of p38MAPK signaling in TNF‑α‑induced apoptosis in glioma cells remains unclear. In the current study, the role of p38MAPK in TNF‑α‑induced apoptosis in rat glioma C6 cells was investigated. TNF‑α was observed to induce cell apoptosis and the phosphorylation of p38MAPK in C6 cells. In addition, the inhibition of p38MAPK markedly reduced TNF‑α‑induced apoptosis, while JNK inhibition did not affect apoptosis. Furthermore, p38MAPK transfection altered the cell cycle of glioma cells and increased the rate of apoptosis. It also led to an increase in the level of soluble TNF‑α in the culture supernatant and membrane TNF receptor I levels in tumor cells. In conclusion, the results of the current study demonstrated that the activation of p38MAPK mediates TNF‑α‑induced apoptosis in glioma C6 cells, suggesting p38MAPK as a potential target for glioma therapy.

Differential temporal expression profiles of heat shock protein genes in Drosophila melanogaster (Diptera: Drosophilidae) under ultraviolet A radiation stress

Solar UV radiation is indispensable for certain behaviors of many organisms. Nevertheless, UV-A might be expected to stress insects that possess intensive positive taxis toward UV-A light. To avoid stress hazards, organisms generally exhibit the upregulation of heat shock proteins (Hsps) expression. To gain a better understanding of the roles of the different Hsps in response to UV-A stress in the diurnal phototactic fly Drosophila melanogaster Meigen, 1830 (Diptera: Drosophilidae), we tested the temporal expression patterns of 11 DmHsps following UV-A radiation. The results indicated that each DmHsp had a differential temporal expression profile under UV-A radiation stress. Potential transcription factor-binding motifs in the promoter regions of strongly inducible DmHsps were identified; results showed these transcription factor-binding motifs were highly homologous to binding sites that have been identified for transcription factors associated with UV radiation stimuli. So DmHsps might act in a coordinated and cooperative manner at the transcriptional level to counteract UV-A radiation-based stress.

Targeting the testis-specific heat-shock protein 70-2 (HSP70-2) reduces cellular growth, migration, and invasion in renal cell carcinoma cells

Renal cell carcinoma (RCC) represents one of the most resistant tumors to radiotherapy and chemotherapy. Current therapies for the RCC patients are limited owing to lack of diagnosis and therapeutic treatments. Testis-specific heat-shock protein 70-2 (HSP70-2), a member of HSP70 chaperone family, has been shown to be associated with various cancers. In the present study, we investigated the putative role of HSP70-2 in various malignant properties of the RCC cells. HSP70-2 messenger RNA (mRNA) and protein expression was investigated in A704, ACHN, and Caki-1 cells derived from the RCC patients. We assessed the expression of HSP70-2 gene and protein by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. The expression of HSP70-2 protein was further validated by performing indirect immunofluorescence (IIF) and flow cytometry. The malignant properties of high-grade invasive A704 and Caki-1 cells, such as cellular proliferation, colony formation, migration, invasion, and wound healing, were evaluated by silencing the expression of HSP70-2 gene in these cells. Statistical significance was defined using Student's t test. Our RT-PCR and Western blotting data showed the expression of HSP70-2 in all RCC cells. Our results showed that HSP70-2 was predominantly expressed in cytoplasm and found to be colocalized with endoplasmic reticulum, mitochondria, Golgi body, and plasma membrane but not the nuclear envelope. Knockdown of HSP70-2 expression with specific short hairpin RNA (shRNA) demonstrated significant reduction in cell growth and colony formation. Further, a marked reduction in cell migration and invasion was also observed, indicating the potential role of HSP70-2 in metastasis. Collectively, our data suggest that HSP70-2 plays a key role in cancerous growth and invasive potential of RCC cells. Thus, HSP70-2 could serve as a novel potential therapeutic target for the RCC.

Glyoxalase I inhibition induces apoptosis in irradiated MCF-7 cells via a novel mechanism involving Hsp27, p53 and NF-κB

BACKGROUND

Glyoxalase I (GI) is a cellular defence enzyme involved in the detoxification of methylglyoxal (MG), a cytotoxic byproduct of glycolysis, and MG-derived advanced glycation end products (AGEs). Argpyrimidine (AP), one of the major AGEs coming from MG modifications of proteins arginines, is a pro-apoptotic agent. Radiotherapy is an important modality widely used in cancer treatment. Exposure of cells to ionising radiation (IR) results in a number of complex biological responses, including apoptosis. The present study was aimed at investigating whether, and through which mechanism, GI was involved in IR-induced apoptosis.

METHODS

Apoptosis, by TUNEL assay, transcript and protein levels or enzymatic activity, by RT-PCR, western blot and spectrophotometric methods, respectively, were evaluated in irradiated MCF-7 breast cancer cells, also in experiments with appropriate inhibitors or using small interfering RNA.

RESULTS

Ionising radiation induced a dramatic reactive oxygen species (ROS)-mediated inhibition of GI, leading to AP-modified Hsp27 protein accumulation that, in a mechanism involving p53 and NF-κB, triggered an apoptotic mitochondrial pathway. Inhibition of GI occurred at both functional and transcriptional levels, the latter occurring via ERK1/2 MAPK and ERα modulation.

CONCLUSIONS

Glyoxalase I is involved in the IR-induced MCF-7 cell mitochondrial apoptotic pathway via a novel mechanism involving Hsp27, p53 and NF-κB.

Phosphorylation of heat shock protein 27 antagonizes TNF-α induced HeLa cell apoptosis via regulating TAK1 ubiquitination and activation of p38 and ERK signaling

Tumor necrosis factor (TNF)-α is a potent cytokine that regulates critical cellular processes including apoptosis. TNF-α usually triggers both survival and apoptotic signals in various cell types. Heat shock protein 27 (HSP27), an important cellular chaperone, is believed to protect cells from apoptosis. HSP27 can be phosphorylated and changed its cellular function according to different stimuli. However, available reports on the role of HSP27 phosphorylation in apoptosis remain elusive. In this study, we investigated the role of HSP27 phosphorylation in TNF-α induced apoptosis in human cervical carcinoma (HeLa) cells. We found that TNF-α induced apoptosis was enhanced if we suppressed the TNF-α induced HSP27 phosphorylation by specific inhibitor CMPD1 or MAPKAPK2 (MK2) knockdown or by overexpression of non-phosphorylatable mutant HSP27-3A. Through co-immunoprecipitation and confocal microscopy, we observed that HSP27 associated with transforming growth factor-β (TGF-β)-activated kinase 1 (TAK1) in response to TNF-α stimulation. By blocking MK2 activity or overexpressing phospho-mimetic mutant Hsp27-3D, we further showed that HSP27 phosphorylation facilitated the TNF-α induced ubiquitination and phosphorylation of TAK1 and the activations of p38 MAPK and ERK, the TAK1 downstream pro-survival signaling. In addition, we also found that increased HSP27 phosphorylation inhibited TRADD ubiquitination but did not influence the binding between TRADD and FADD in a pro-apoptotic complex. Taken together, our data indicated that HSP27 phosphorylation was involved in modulating the TNF-α induced apoptosis via interacting with TAK1 and regulating TAK1 post-translational modifications in HeLa cells. This study demonstrates that HSP27 phosphorylation serves as a novel regulator in TNF-α-induced apoptosis, and provides a new insight into the cytoprotective role of HSP27 phosphorylation.

Contribution of small heat shock proteins to muscle development and function

Investigations undertaken over the past years have led scientists to introduce the concept of protein quality control (PQC) systems, which are responsible for polypeptide processing. The PQC system monitors proteostasis and involves activity of different chaperones such as small heat shock proteins (sHSPs). These proteins act during normal conditions as housekeeping proteins regulating cellular processes, and during stress conditions. They also mediate the removal of toxic misfolded polypeptides and thereby prevent development of pathogenic states. It is postulated that sHSPs are involved in muscle development. They could act via modulation of myogenesis or by maintenance of the structural integrity of signaling complexes. Moreover, mutations in genes coding for sHSPs lead to pathological states affecting muscular tissue functioning. This review focuses on the question how sHSPs, still relatively poorly understood proteins, contribute to the development and function of three types of muscle tissue: skeletal, cardiac and smooth.

Transduced protein transduction domain linked HSP27 protected LECs against UVB radiation-induced damage

PTD-fusion protein technology was used to transduce heat shock protein 27 (HSP27), an anti-apoptotic protein, into human lens epithelial cells (HLECs) (SRA01/04). The protein transduction domain (PTD) of the 11-amino acid YGRKKRRQRRR was tagged at the N-terminus of HSP27. The fusion protein was purified from bacteria transformed with a pKYB-PTD-HSP27 construct. The HLECs were incubated with PTD-HSP27-FITC and the fluorescence inside HLECs was found by fluorescence microscopic examination. To test the ability of PTD-HSP27 to pass through the corneas, PTD-HSP27-FITC was dropped onto the conjunctival sacs of rabbits; fluorescent labeled PTD-HSP27 was then observed in the rabbit aqueous humor. After being incubated with the PTD-HSP27 protein and irradiated with ultraviolet-B (UVB) light, HLECs was analyzed by flow cytometry, Hoechst 33258 staining and measurement of the potential of the mitochondrial transmembrane. HLECs incubated with PTD-HSP27 had a lower apoptotic rate and a higher mitochondrial membrane potential than the control cells. PTD-HSP27 appears to be sufficient to protect HLECs against UVB-induced apoptosis.

Synergistic effect of lung tumor-associated dendritic cell-derived HB-EGF and CXCL5 on cancer progression

The interaction between cancer cells and their microenvironment is a paradoxical cycle that exacerbates cancer progression and results in metastasis. Our study investigated the mechanism underlying the synergistic enhancement of release of soluble factors from tumor-associated dendritic cells and its effect on cancer development. The combination of HB-EGF (heparin-binding EGF-like growth factor) and CXCL5 (CXCL5/epithelial neutrophil-activating peptide-78) produced a strong synergistic effect on cancer proliferation, epithelial-mesenchymal transition, migration and invasion. CXCL5 not only potentiated the classical EGFR pathway and the AKT and ERK/RSK1/2 signaling pathways but also increased the phosphorylation of heat shock protein 27 (HSP27), which was slightly increased in A549 cells treated with either HB-EGF or CXCL5 only. Phosphorylated HSP27 stabilized sustained AKT activity by direct interaction, leading to enhanced tumor spheroid formation. Knockdown of HSP27 by shRNA decreased HB-EGF plus CXCL5-mediated tumor spheroid formation in a three-dimensional culture system, suggesting that AKT/HSP27 was required for HB-EGF/CXCL5-mediated cancer progression. Inhibiting RSK also reduces the modulation of c-Fos phosphorylation, Snail upregulation and cell migration by HB-EGF plus CXCL5, suggesting a synergistic effect of ERK/RSK and HB-EGF plus CXCL5 on cell migration. In mice, CXCL5 antibody synergistically enhances the efficiency of the tyrosine kinase inhibitor, gefitinib, without increasing its toxicity. These results provide evidence that elucidates potential cross-points between extracellular signals affecting lung cancer progression. Targeting CXCL5 may provide therapeutic benefits for lung cancer chemotherapy or immunotherapy.

Molecular targets on the horizon for kidney and urothelial cancer

As whole-genome sequencing technology rapidly advances, the insights gained from deciphering cancer genomes are shifting the paradigm in the diagnosis and treatment of cancer with the promise of individualized treatment for each patient. Information gained in this way is extensive for certain cancers, but fairly limited in renal cell carcinomas and urothelial carcinoma. Mutations in multiple, potentially druggable genes have been identified in urothelial carcinomas; however, the association between molecular alterations and clinical outcome has not yet been robustly demonstrated. Data in this area are emerging in renal cell carcinoma, leading to the development of targeted agents that have improved overall survival. Unfortunately, these treatments rarely yield complete responses, are not curative, and development of resistance ensues. This Review will focus on the biology of non-hormonally driven urological cancers. We discuss how approaches using whole-genome sequencing can facilitate the discovery of biomarkers of drug sensitivity in both renal cell carcinomas and urothelial carcinomas. For renal cell carcinomas, we will describe how genomic and epigenomic mining has uncovered novel genes and pathways involved in tumorigenesis, tumour classification and mechanisms of resistance in the various subsets of this disease and the potential for exploiting these discoveries in the clinic.

Phosphorylated Hsp27 activates ATM-dependent p53 signaling and mediates the resistance of MCF-7 cells to doxorubicin-induced apoptosis

DNA damage activates p53 and its downstream target genes, which further leads to apoptosis or survival either by the cell cycle arrest or by DNA repair. In many tumors, the heat shock protein 27 (Hsp27) is expressed at high levels to provide protection against anticancer drugs. However, the roles of Hsp27 in p53-mediated cellular responses to DNA damage are controversial. Here, we investigated the interplay between the phosphorylation status of Hsp27 and p53 in kidney 293A (HEK293A) cells and found that over-expressing phosphorylated Hsp27 mimics (Hsp27-3D) activated p53/p21 in an ATM-dependent manner. In addition, incubation with doxorubicin (Dox), an anticancer drug, induced Hsp27 phosphorylation in human adenocarcinoma cells (MCF-7). In contrast, inhibition of Hsp27 phosphorylation retarded both p53 induction and p21 accumulation, and led to cell apoptosis. Furthermore, phosphorylated Hsp27 increased p53 nuclear importing and its downstream target gene expression such as p21 and MDM2, while de-phosphorylated Hsp27 impeded this procession. Taken together, our data suggest that Hsp27, in its phosphorylated or de-phosphorylated status, plays different roles in regulating p53 pathway and cell survival.

HSP27 expression in primary colorectal cancers is dependent on mutation of KRAS and PI3K/AKT activation status and is independent of TP53

Colorectal adenomas display features of senescence, but these are often lost upon progression to carcinoma, indicating that oncogene induced senescence (OIS) could be a roadblock in colorectal cancer (CRC) development. Heat shock proteins (HSPs) have been implicated in the prognosis of CRC and HSP based therapy is a current interest for drug development. Recent cell culture studies have suggested that in the absence of a TP53 mutation, OIS mediated by PI3K/AKT activation can be circumvented by high expression of HSPs. Furthermore, while PI3K/AKT activation and KRAS mutations are independent inducers of OIS, PI3K/AKT activation can suppress KRAS-induced OIS when both are present in cultured cells. As KRAS mutations, PI3K/AKT activation and TP53 mutations are all common features of CRC, it is possible that the requirement for HSP to inhibit OIS in CRC is dependent on the mutation spectrum of a tumour. However, work on HSP that utilised mutation profiled human tumour tissues has been limited. Here, we characterised the expression of two major HSP proteins (HSP27 and 72) by immunohistochemistry (IHC), the mutation status of TP53, KRAS and PIK3CA genes by direct sequencing and the activation status of AKT by IHC in a cohort of unselected primary CRC (n=74). We compare our data with findings generated from cell-based studies. Expression of HSP27 and HSP72 was correlated to clinicopathological and survival data but no significant association was found. We also established the mutation status of TP53, KRAS and PIK3CA genes and the activation status of AKT in our CRC panel. We did not detect any associations between HSP27 or HSP72 expression with TP53 mutation status. However, HSP27 expression in CRCs was strongly associated with the co-presence of wildtype KRAS and activated PI3K/AKT (p=0.004), indicating a possible role of HSP27 in overcoming PI3K/AKT induced OIS in tumours. Our studies suggest a role for using archival tissues in validating hypotheses generated from cell culture based investigations.

Proteomic investigation of anti-tumor activities exerted by sinularin against A2058 melanoma cells

The extracts from soft corals have been increasingly investigated for biomedical and therapeutic purposes. The aim of this study is to examine and analyze the anti-tumor effects of the genus Sinularia extract sinularin on A2058 melanoma cells using MTT assay, cell migration assay, wound healing assay, flow cytometric analysis, and proteomic analysis. Sinularin dose-dependently (1-5 μg/mL) inhibited melanoma cell proliferation while the treatment at identical concentrations suppressed cell migration. Sinularin dose-dependently enhanced apoptotic melanoma cells and caused tumor cell accumulation at G2/M phase, indicating that sinularin exerts apoptosis-induced and cell cycle-delayed activities in A2058 melanoma cells. Comparative proteomic analysis was conducted to investigate the effects of sinularin at the molecular level by comparison between the protein profiling of melanoma cells treated with sinularin and without the treatment. Thirty-five differential proteins (13 upregulated and 22 downregulated) concerning the treatment were identified by liquid chromatography-tandem mass spectrometry. Proteomic data and Western blot displayed the levels of several tumor inhibitory or apoptosis-associated proteins including annexin A1, voltage-dependent anion-selective channel protein 1 and prohibitin (upregulated), heat shock protein 60, heat shock protein beta-1, and peroxiredoxin-2 (downregulated) in A2058 melanoma cells exposed to sinularin. Increased expression of p53, cleaved-caspase-3, cleaved-caspase-8, cleaved-caspase-9, p21, and Bax and decreased expression of Bcl-2 in sinularin-treated melanoma cells suggest that the anti-tumor activities of sinularin against melanoma cells are particularly correlated with these pro-apoptotic factors. These data provide important information for the mechanisms of anti-tumor effects of sinularin on melanoma cells and may be helpful for drug development and progression monitoring of human melanoma.

Cotargeting stress-activated Hsp27 and autophagy as a combinatorial strategy to amplify endoplasmic reticular stress in prostate cancer

Hsp27 is a stress-activated multifunctional chaperone that inhibits treatment-induced apoptosis and causes treatment resistance in prostate and other cancers. We previously showed that targeted suppression of Hsp27 sensitizes cancer cells to hormone and chemotherapy. However, mechanisms by which Hsp27 confers cell treatment resistance are incompletely defined. Here, we report that Hsp27 protects human prostate cancer cells against proteotoxic stress induced by proteasome inhibition, and that Hsp27 silencing using siRNA or antisense (OGX-427) induced both apoptosis and autophagy through mechanisms involving reduced proteasome activity and induction of endoplasmic reticulum (ER) stress. We found that autophagy activation protected against ER stress-induced cell death, whereas inhibition of autophagy activation following Hsp27 silencing using either pharmacologic inhibitors or atg3 silencing enhanced cell death. Importantly, cotargeting Hsp27 and autophagy by combining OGX-427 with the autophagy inhibitor, chloroquine, significantly delayed PC-3 prostate tumor growth in vivo. These findings identify autophagy as a cytoprotective, stress-induced adaptive pathway, activated following disruption of protein homeostasis and ER stress induced by Hsp27 silencing. Combinatorial cotargeting cytoprotective Hsp27 and autophagy illustrates potential benefits of blocking activation of adaptive pathways to improve treatment outcomes in cancer.

Small heat shock proteins HSP27 (HspB1), αB-crystallin (HspB5) and HSP22 (HspB8) as regulators of cell death

Hsp27, αB-crystallin and HSP22 are ubiquitous small heat shock proteins (sHsp) whose expression is induced in response to a wide variety of unfavorable physiological and environmental conditions. These sHsp protect cells from otherwise lethal conditions mainly by their involvement in cell death pathways such as necrosis, apoptosis or autophagy. At a molecular level, the mechanisms accounting for sHsp functions in cell death are (1) prevention of denatured proteins aggregation, (2) regulation of caspase activity, (3) regulation of the intracellular redox state, (4) function in actin polymerization and cytoskeleton integrity and (5) proteasome-mediated degradation of selected proteins. In cancer cells, these sHsp are often overexpressed and associated with increased tumorigenicity, cancer cells metastatic potential and resistance to chemotherapy. Altogether, these properties suggest that Hsp27, αB-crystallin and Hsp22 are appropriate targets for modulating cell death pathways. In the present, we briefly review recent reports showing molecular evidence of cell death regulation by these sHsp and co-chaperones. This article is part of a Directed Issue entitled: Small HSPs in physiology and pathology.

Signaling network state predicts twist-mediated effects on breast cell migration across diverse growth factor contexts

Epithelial-mesenchymal transition (EMT), whether in developmental morphogenesis or malignant transformation, prominently involves modified cell motility behavior. Although major advances have transpired in understanding the molecular pathways regulating the process of EMT induction per se by certain environmental stimuli, an important outstanding question is how the activities of signaling pathways governing motility yield the diverse movement behaviors characteristic of pre-induction versus postinduction states across a broad landscape of growth factor contexts. For the particular case of EMT induction in human mammary cells by ectopic expression of the transcription factor Twist, we found the migration responses to a panel of growth factors (EGF, HRG, IGF, HGF) dramatically disparate between confluent pre-Twist epithelial cells and sparsely distributed post-Twist mesenchymal cells—but that a computational model quantitatively integrating multiple key signaling node activities could nonetheless account for this full range of behavior. Moreover, motility in both conditions was successfully predicted a priori for an additional growth factor (PDGF) treatment. Although this signaling network state model could comprehend motility behavior globally, modulation of the network interactions underlying the altered pathway activities was identified by ascertaining differences in quantitative topological influences among the nodes between the two conditions.

Forced expression of heat shock protein 27 (Hsp27) reverses P-glycoprotein (ABCB1)-mediated drug efflux and MDR1 gene expression in Adriamycin-resistant human breast cancer cells

Mutant p53 accumulation has been shown to induce the multidrug resistance gene (MDR1) and ATP binding cassette (ABC)-based drug efflux in human breast cancer cells. In the present work, we have found that transcriptional activation of the oxidative stress-responsive heat shock factor 1 (HSF-1) and expression of heat shock proteins, including Hsp27, which is normally known to augment proteasomal p53 degradation, are inhibited in Adriamycin (doxorubicin)-resistant MCF-7 cells (MCF-7/adr). Such an endogenous inhibition of HSF-1 and Hsp27 in turn results in p53 mutation with gain of function in its transcriptional activity and accumulation in MCF-7/adr. Also, lack of HSF-1 enhances nuclear factor κB (NF-κB) DNA binding activity together with mutant p53 and induces MDR1 gene and P-glycoprotein (P-gp, ABCB1), resulting in a multidrug-resistant phenotype. Ectopic expression of Hsp27, however, significantly depleted both mutant p53 and NF-κB (p65), reversed the drug resistance by inhibiting MDR1/P-gp expression in MCF-7/adr cells, and induced cell death by increased G(2)/M population and apoptosis. We conclude from these results that HSF-1 inhibition and depletion of Hsp27 is a trigger, at least in part, for the accumulation of transcriptionally active mutant p53, which can either directly or NF-κB-dependently induce an MDR1/P-gp phenotype in MCF-7 cells. Upon Hsp27 overexpression, this pathway is abrogated, and the acquired multidrug resistance is significantly abolished so that MCF-7/adr cells are sensitized to Dox. Thus, clinical alteration in Hsp27 or NF-κB level will be a potential approach to circumvent drug resistance in breast cancer.