Overexpression of DNAJB6 promotes colorectal cancer cell invasion through an IQGAP1/ERK-dependent signaling pathway

DNAJC8: a prognostic marker and potential therapeutic target for hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is the most common type of liver cancer, accounting for ~90% of the total cases. DnaJ heat shock protein family member C8 (DNAJC8), belonging to the heat shock protein 40 (HSP40) family, is known to regulate cancer biology function. However, the role of DNAJC8 on HCC development remains unknown.

Methods

The Cancer Genome Atlas, GTEx, cBioPortal, and Human Protein Atlas were used to analyze the expression and clinical significance of DNAJC8 in HCC. Two HCC cell lines, MHCC-97H and Huh-7, were utilized to determine the biological function of DNAJC8.

Results

DNAJC8 expression was upregulated in HCC tissues and correlated with poor clinical prognosis. It was closely related to spliceosome, nucleocytoplasmic transport, and cell cycle and might be involved in the formation of tumor immunosuppressive microenvironment. Knockdown of DNAJC8 severely inhibited HCC cell proliferation and induced apoptosis.

Conclusion

Our study demonstrate that DNAJC8 functions as an oncogene in HCC and hence may be used as a potential therapeutic target and prognostic marker for HCC.

Development of novel DNAJB6-KIAA1522-p-mTOR three-protein prognostic prediction models for CRC

BACKGROUND

To evaluate the prognostic value of DNAJB6, KIAA1522, and p-mTOR expression for colorectal cancer (CRC) and to develop effective prognostic models for CRC patients.

METHODS

The expression of DNAJB6, KIAA1522, and p-mTOR (Ser2448) was detected using immunohistochemistry in 329 CRC specimens. The prognostic values of the three proteins in the training cohort were assessed using Kaplan-Meier curves and univariate and multivariate Cox proportional hazards models. Prediction nomogram models integrating the three proteins and TNM stage were constructed. Subsequently, calibration curves, receiver operating characteristic (ROC) curves, the concordance index (C-index), and decision curve analysis (DCA) were used to evaluate the performance of the nomograms in the training and validation cohorts.

RESULTS

The three proteins DNAJB6, KIAA1522, and p-mTOR were significantly overexpressed in CRC tissues (each P < 0.01), and their expression was an independent prognostic factor for overall survival (OS) and disease-free survival (DFS) (each P < 0.05). The area under the ROC curves (AUC) and C-index values were approximately 0.7. Additionally, the calibration curves showed that the predicted values and the actual values fit well. Furthermore, DCA curves indicated that the clinical value of the nomogram models was higher than that of TNM stage. Overall, the novel prediction models have good discriminability, sensitivity, specificity and clinical utility.

CONCLUSION

The nomograms containing DNAJB6, KIAA1522, and p-mTOR may be promising models for predicting postoperative survival in CRC.

Multi-Faceted Roles of DNAJB Protein in Cancer Metastasis and Clinical Implications

Heat shock proteins (HSPs) are highly conserved molecular chaperones with diverse cellular activities, including protein folding, assembly or disassembly of protein complexes, and maturation process under diverse stress conditions. HSPs also play essential roles in tumorigenesis, metastasis, and therapeutic resistance across cancers. Among them, HSP40s are widely accepted as regulators of HSP70/HSP90 chaperones and an accumulating number of biological functions as molecular chaperones dependent or independent of either of these chaperones. Despite large numbers of HSP40s, little is known about their physiologic roles, specifically in cancer progression. This article summarizes the multi-faceted role of DNAJB proteins as one subclass of the HSP40 family in cancer development and metastasis. Regulation and deregulation of DNAJB proteins at transcriptional, post-transcriptional, and post-translational levels contribute to tumor progression, particularly cancer metastasis. Furthermore, understanding differences in function and regulating mechanism between DNAJB proteins offers a new perspective on tumorigenesis and metastasis to improve therapeutic opportunities for malignant diseases.

The role of heat shock proteins in metastatic colorectal cancer: A review

Heat shock proteins (HSPs) are a large molecular chaperone family classified by their molecular weights, including HSP27, HSP40, HSP60, HSP70, HSP90, and HSP110. HSPs are likely to have antiapoptotic properties and participate actively in various processes such as tumor cell proliferation, invasion, metastases, and death. In this review, we discuss comprehensively the functions of HSPs associated with the progression of colorectal cancer (CRC) and metastasis and resistance to cancer therapy. Taken together, HSPs have numerous clinical applications as biomarkers for cancer diagnosis and prognosis and potential therapeutic targets for CRC and its related metastases.

Novel Prognostic Signature for Acute Myeloid Leukemia: Bioinformatics Analysis of Combined CNV-Driven and Ferroptosis-Related Genes

Background: Acute myeloid leukemia (AML), which has a difficult prognosis, is the most common hematologic malignancy. The role of copy number variations (CNVs) and ferroptosis in the tumor process is becoming increasingly prominent. We aimed to identify specific CNV-driven ferroptosis-related genes (FRGs) and establish a prognostic model for AML.

Methods: The combined analysis of CNV differential data and differentially expressed genes (DEGs) data from The Cancer Genome Atlas (TCGA) database was performed to identify key CNV-driven FRGs for AML. A risk model was constructed based on univariate and multivariate Cox regression analysis. The Gene Expression Omnibus (GEO) dataset was used to validate the model. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted to clarify the functional roles of DEGs and CNV-driven FRGs.

Results: We identified a total of 6828 AML-related DEGs, which were shown to be significantly associated with cell cycle and immune response processes. After a comprehensive analysis of CNVs and corresponding DEGs and FRGs, six CNV-driven FRGs were identified, and functional enrichment analysis indicated that they were involved in oxidative stress, cell death, and inflammatory response processes. Finally, we screened 2 CNV-driven FRGs (DNAJB6 and HSPB1) to develop a prognostic risk model. The overall survival (OS) of patients in the high-risk group was significantly shorter in both the TCGA and GEO (all p < 0.05) datasets compared to the low-risk group.

Conclusion: A novel signature based on CNV-driven FRGs was established to predict the survival of AML patients and displayed good performance. Our results may provide potential targets and new research ideas for the treatment and early detection of AML.

The role of heat shock protein 40 in carcinogenesis and biology of colorectal cancer

Colorectal cancer (CRC) is the third most common cancer worldwide. Despite the enormous amount of effort in the diagnosis and treatment of CRC, the overall survival rate of patients remains low. The precise molecular and cellular basis underlying CRC has not been completely understood yet. Over time, new genes and molecular pathways involved in the pathogenesis of the disease are being identified. Accurate discovery of these genes and signaling pathways are important and urgent missions for the next generation of anticancer therapy research. Chaperone DnaJ, also known as Hsp40 (heat shock protein 40), has been of particular interest in CRC pathogenesis, as it is involved in the fundamental cell activities for maintaining cellular homeostasis. Evidence show that protein family members of DnaJ/Hsp40 play both roles; enhancing and reducing the growth of CRC cells. In the present review, we focus on the current knowledge on the molecular mechanisms responsible for the role of DnaJ/Hsp40 in CRC carcinogenesis and biology.

DNAJB8 in small extracellular vesicles promotes Oxaliplatin resistance through TP53/MDR1 pathway in colon cancer

Chemotherapy is one of the most frequently used therapies for the treatment of colon cancer (COAD). However, Oxaliplatin (L-OHP) resistance is a major obstacle to the effective treatment of COAD. Here, we investigated whether DNAJB8, a heat shock protein 40 (HSP40) family protein, could be used for the prognosis and therapy of L-OHP resistance in COAD. Treatment with small interfering RNA targeting DNAJB8 could restore the response to L-OHP in vitro and in vivo. On the mechanism, we demonstrated that DNAJB8 could interact with TP53 and inhibit the ubiquitination degradation of TP53, leading to MDR1 upregulation which promotes colon cancer L-OHP resistance. We found that small extracellular vesicle (sEV)-mediated transfer of DNAJB8 from L-OHP-resistant COAD cells to sensitive cells contributed to L-OHP resistance. A prognostic signature based on the DNAJB8 levels in both tissue and serum showed that COAD patients with high-risk scores exhibited significantly worse overall survival and disease-free survival than patients with low-risk scores. These results indicate that DNAJB8 levels in serum sEVs may serve as a biomarker for COAD. DNAJB8 from sEVs might be a promising therapeutic target for L-OHP resistance and a prognostic predictor of clinical response.

Heat shock protein A12A activates migration of hepatocellular carcinoma cells in a monocarboxylate transporter 4-dependent manner

Metastasis is responsible for most of the hepatocellular carcinoma (HCC)-associated death. However, its underlying mechanism has yet to be fully elucidated. Glycolysis-derived lactate has been shown to be a powerful regulator of cancer metastasis. Heat shock protein A12A (HSPA12A) encodes a novel member of HSP70 family. We have recently demonstrated that heat shock protein A12A (HSPA12A) inhibited renal cancer cell migration by suppressing lactate output and glycolytic activity, which were mediated by unstabilizing CD147 and promoting its degradation. By striking contrast, here we demonstrated that HSPA12A promoted migration of human HCC cells. Extracellular acidification, lactate export, and glycolytic activity in HCC cells were also promoted following HSPA12A overexpression. Further analysis revealed that HSPA12A interacted with MCT4 and increased its membrane localization, thereby promoting export of lactate generated from glycolysis; this led, ultimately, to HCC cell migration. Our results revealed the opposite effect of HSPA12A on migration of renal cancer cells and that of HCC cells. Of note, in contrast to the inhibitory effect on CD147 expression in renal cancer cells, we found that HSPA12A increased CD147 expression in HCC cells, indicating that the expression of CD147 might exist heterogeneity in different cancer cell types. Taken together, we identified HSPA12A as an activator of HCC migration, a role opposite to that of renal cancer cells. Inhibiting HSPA12A might be a potential therapeutic intervention for HCC metastasis.

Regulation of p53 and Cancer Signaling by Heat Shock Protein 40/J-Domain Protein Family Members

Heat shock proteins (HSPs) are molecular chaperones that assist diverse cellular activities including protein folding, intracellular transportation, assembly or disassembly of protein complexes, and stabilization or degradation of misfolded or aggregated proteins. HSP40, also known as J-domain proteins (JDPs), is the largest family with over fifty members and contains highly conserved J domains responsible for binding to HSP70 and stimulation of the ATPase activity as a co-chaperone. Tumor suppressor p53 (p53), the most frequently mutated gene in human cancers, is one of the proteins that functionally interact with HSP40/JDPs. The majority of p53 mutations are missense mutations, resulting in acquirement of unexpected oncogenic activities, referred to as gain of function (GOF), in addition to loss of the tumor suppressive function. Moreover, stability and levels of wild-type p53 (wtp53) and mutant p53 (mutp53) are crucial for their tumor suppressive and oncogenic activities, respectively. However, the regulatory mechanisms of wtp53 and mutp53 are not fully understood. Accumulating reports demonstrate regulation of wtp53 and mutp53 levels and/or activities by HSP40/JDPs. Here, we summarize updated knowledge related to the link of HSP40/JDPs with p53 and cancer signaling to improve our understanding of the regulation of tumor suppressive wtp53 and oncogenic mutp53 GOF activities.

Role of IQGAP1 in Carcinogenesis

Scaffolding proteins can play important roles in cell signaling transduction. IQ motif-containing GTPase-activating protein 1 (IQGAP1) influences many cellular activities by scaffolding multiple key signaling pathways, including ones involved in carcinogenesis. Two decades of studies provide evidence that IQGAP1 plays an essential role in promoting cancer development. IQGAP1 is overexpressed in many types of cancer, and its overexpression in cancer is associated with lower survival of the cancer patient. Here, we provide a comprehensive review of the literature regarding the oncogenic roles of IQGAP1. We start by describing the major cancer-related signaling pathways scaffolded by IQGAP1 and their associated cellular activities. We then describe clinical and molecular evidence for the contribution of IQGAP1 in different types of cancers. In the end, we review recent evidence implicating IQGAP1 in tumor-related immune responses. Given the critical role of IQGAP1 in carcinoma development, anti-tumor therapies targeting IQGAP1 or its associated signaling pathways could be beneficial for patients with many types of cancer.

The interplay between IQGAP1 and small GTPases in cancer metastasis

The metastatic spread of tumor cells to distant anatomical locations is a critical cause for disease progression and leads to more than 90 % of cancer-related deaths. IQ motif-containing GTPase-activating protein 1 (IQGAP1), a prominent regulator in the cancer metastasis process, is a scaffold protein that interacts with components of the cytoskeleton. As a critical node within the small GTPase network, IQGAP1 acts as a binding partner of several small GTPases, which in turn function as molecular switches to control most cellular processes, including cell migration and invasion. Given the significant interaction between IQGAP1 and small GTPases in cancer metastasis, we briefly elucidate the role of IQGAP1 in regulating cancer metastasis and the varied interactions existing between IQGAP1 and small GTPases. In addition, the potential regulators for IQGAP1 activity and its interaction with small GTPases are also incorporated in this review. Overall, we comprehensively summarize the role of IQGAP1 in cancer tumorigenicity and metastasis, which may be a potential anti-tumor target to restrain cancer progression.

Prognostic role of aberrant mTOR activation in patients with stage II and III colorectal cancer

Aim: This study aimed to develop an effective risk predictor for patients with stage II and III colorectal cancer (CRC). Materials & methods: The prognostic value of p-mTOR (Ser2448) levels was analyzed using Kaplan-Meier survival analysis and Cox regression analysis. Results: The levels of p-mTOR were increased in CRC specimens and significantly correlated with poor prognosis in patients with stage II and III CRC. Notably, the p-mTOR level was an independent poor prognostic factor for disease-free survival and overall survival in stage II CRC. Conclusion: Aberrant mTOR activation was significantly associated with the risk of recurrence or death in patients with stage II and III CRC, thus this activated proteins that may serve as a potential biomarker for high-risk CRC.

Plastin 1 drives metastasis of colorectal cancer through the IQGAP1/Rac1/ERK pathway

Tumor metastasis is the dominant cause of death in colorectal cancer (CRC) patients, and it often involves dysregulation of various cytoskeletal proteins. Plastin 1 (PLS1) is an actin-bundling protein that has been implicated in the structure of intestinal epithelial microvilli; however, its role in CRC metastasis has not yet been determined. In this study, we demonstrated that PLS1 is highly expressed in 33.3% (45/135) of CRC patients and is correlated with lymph node metastasis and poor survival. In in vitro and in vivo experiments, PLS1 induced the migration and invasion of CRC cells and the metastases to the liver and lung in mice. Moreover, the expressions of key factors for CRC metastases, matrix metalloproteinase (MMP) 9 and 2, were enhanced by PLS1, which was dependent on phosphorylating ERK1/2 activated by IQGAP1/Rac1 signaling. The connection between these signals and PLS1 was further confirmed in CRC tissues of patients and the metastatic nodules from a mouse model. These findings suggest that PLS1 promotes CRC metastasis through the IQGAP1/Rac1/ERK pathway. Targeting PLS1 may provide a potential approach to inhibit the metastasis of CRC cells.

DNAJB6 Promotes Ferroptosis in Esophageal Squamous Cell Carcinoma

BACKGROUND

DnaJ/Hsp40 homolog, subfamily B, member 6 (DNAJB6) is significantly down-regulated in esophageal squamous cell carcinoma (ESCC), while its complicated molecular mechanisms are still unknown.

AIMS

To investigate the relationship between DNAJB6 and ESCC.

METHODS

The expression of DNAJB6 was detected in ESCC patient by Western blot and immunohistochemistry. To overexpress DNAJB6a by lentivirus infection, colony-forming, CCK-8, transwell, mouse xenograft assays were utilized to verify the proliferous, invasive, and migratory role of DNAJB6a in ESCC cells. The MDA and GSH assays determine whether DNAJB6a participates in cell redox reaction. The variation of AKT and GPX4 was detected by Western blot.

RESULTS

The correlation between DNAJB6 level and lymph node metastasis in ESCC patient was negative. Overexpressing DNAJB6a shows tumor-suppressive effects in vitro and in vivo. In addition, DNAJB6a overexpression was accompanied together with a remarkable reduction in the protein levels of GPX4 and phosphorylated AKT (p-AKT).

CONCLUSION

DNAJB6 plays an important anti-oncogenic role in ESCC evolvement via ferroptosis.

Heat Shock Proteins: Agents of Cancer Development and Therapeutic Targets in Anti-Cancer Therapy

Heat shock proteins (HSPs) constitute a large family of molecular chaperones classified by their molecular weights, and they include HSP27, HSP40, HSP60, HSP70, and HSP90. HSPs function in diverse physiological and protective processes to assist in maintaining cellular homeostasis. In particular, HSPs participate in protein folding and maturation processes under diverse stressors such as heat shock, hypoxia, and degradation. Notably, HSPs also play essential roles across cancers as they are implicated in a variety of cancer-related activities such as cell proliferation, metastasis, and anti-cancer drug resistance. In this review, we comprehensively discuss the functions of HSPs in association with cancer initiation, progression, and metastasis and anti-cancer therapy resistance. Moreover, the potential utilization of HSPs to enhance the effects of chemo-, radio-, and immunotherapy is explored. Taken together, HSPs have multiple clinical usages as biomarkers for cancer diagnosis and prognosis as well as the potential therapeutic targets for anti-cancer treatment.

A PI3K/AKT Scaffolding Protein, IQ Motif-Containing GTPase Associating Protein 1 (IQGAP1), Promotes Head and Neck Carcinogenesis

PURPOSE

Head and neck cancer (HNC) is the sixth most common cancer worldwide with a 5-year survival rate of less than 50%. The PI3K/AKT/mTOR signaling pathway is frequently implicated in HNC. Recently, IQ motif-containing GTPase-activating protein 1 (IQGAP1) was discovered to scaffold the PI3K/AKT signaling pathway. IQGAP1 gene expression is increased in HNC, raising the hypothesis that IQGAP1 contributes to HNC.

EXPERIMENTAL DESIGN

We performed a combination of in vitro studies using human cancer cell lines treated with a cell-permeable peptide that interferes with IQGAP1's ability to bind to PI3K, and in vivo studies utilizing mice genetically knocked out for the Iqgap1 (Iqgap1 ^-/-). In vivo EGF stimulation assays were used to evaluate PI3K signaling. To study the role of IQGAP1 in HNC, we used a well-validated mouse model that drives HNC via a synthetic oral carcinogen, 4-nitroquinoline 1-oxide (4NQO).

RESULTS

IQGAP1 is necessary for efficient PI3K signaling in vitro and in vivo. Disruption of IQGAP1-scaffolded PI3K/AKT signaling reduced HNC cell survival. Iqgap1 ^-/- mice had significantly lower cancer incidences, lesser disease severity, and fewer cancer foci. IQGAP1 protein levels were increased in HNC arising in Iqgap1^+/+ mice. The level of PI3K signaling in 4NQO-induced HNC arising in Iqgap1 ^-/- mice was significantly reduced, consistent with the hypothesis that IQGAP1 contributes to HNC at least partly through PI3K signaling. High IQGAP1 expression correlated with reduced survival, and high pS6 levels correlated with high IQGAP1 levels in patients with HNC.

CONCLUSIONS

These data demonstrate that IQGAP1 contributes to head and neck carcinogenesis.

Whole genome sequencing reveals complexity in both HPV sequences present and HPV integrations in HPV-positive oropharyngeal squamous cell carcinomas

BACKGROUND

High risk human papillomaviruses (HPV) plays important roles in the development of cervical cancer, a number of other anogenital cancer and they are increasingly found in oropharyngeal squamous cell carcinoma (OPSCC), however there has not been comprehensive analysis about the role how these viruses play in the development of OPSCC.

METHODS

To characterize the physical status of HPV within OPSCC and to determine the effect this has throughout the host genome, we have performed 30-40X whole genome sequencing (WGS) on the BGI sequencing platform on 34 OPSCCs: 28 of which were HPV positive. We then examined the sequencing data to characterize the HPV copy number and HPV physical status to determine what effect they have on both HPV and human genome structural changes.

RESULTS

WGS determined the HPV copy number across the viral genome. HPV copy number ranged from 1 copy to as high as 150 copies in each individual OPSCC. Independent of HPV copy number, most tumors had either a small or a very large deletion in the viral genome. We discovered that these deletions were the result of either HPV integration into the human genome or HPV-HPV sequence junctions. WGS revealed that ~ 70% of these tumors had HPV integrations within the human genome and HPV integration occurred independent of HPV copy number. Individual HPV integrations were found to be highly disruptive resulting in structural variations and copy number changes at or around the integration sites.

CONCLUSIONS

WGS reveals that there is a great complexity in both HPV sequences present and the HPV integrations events in HPV positive OPSCCs tumors. Thus HPV may be playing different roles in the development of different OPSCCs and this further challenge the HPV-driven carcinogenesis model first proposed for cervical cancer.

Network-based analysis of oligodendrogliomas predicts novel cancer gene candidates within the region of the 1p/19q co-deletion

Oligodendrogliomas are primary human brain tumors with a characteristic 1p/19q co-deletion of important prognostic relevance, but little is known about the pathology of this chromosomal mutation. We developed a network-based approach to identify novel cancer gene candidates in the region of the 1p/19q co-deletion. Gene regulatory networks were learned from gene expression and copy number data of 178 oligodendrogliomas and further used to quantify putative impacts of differentially expressed genes of the 1p/19q region on cancer-relevant pathways. We predicted 8 genes with strong impact on signaling pathways and 14 genes with strong impact on metabolic pathways widespread across the region of the 1p/19 co-deletion. Many of these candidates (e.g. ELTD1, SDHB, SEPW1, SLC17A7, SZRD1, THAP3, ZBTB17) are likely to push, whereas others (e.g. CAP1, HBXIP, KLK6, PARK7, PTAFR) might counteract oligodendroglioma development. For example, ELTD1, a functionally validated glioblastoma oncogene located on 1p, was overexpressed. Further, the known glioblastoma tumor suppressor SLC17A7 located on 19q was underexpressed. Moreover, known epigenetic alterations triggered by mutated SDHB in paragangliomas suggest that underexpressed SDHB in oligodendrogliomas may support and possibly enhance the epigenetic reprogramming induced by the IDH-mutation. We further analyzed rarely observed deletions and duplications of chromosomal arms within oligodendroglioma subcohorts identifying putative oncogenes and tumor suppressors that possibly influence the development of oligodendroglioma subgroups. Our in-depth computational study contributes to a better understanding of the pathology of the 1p/19q co-deletion and other chromosomal arm mutations. This might open opportunities for functional validations and new therapeutic strategies.

Emerging roles and underlying molecular mechanisms of DNAJB6 in cancer

DNAJB6 also known as mammalian relative of DnaJ (MRJ) encodes a highly conserved member of the DnaJ/Hsp40 family of co-chaperone proteins that function with Hsp70 chaperones. DNAJB6 is widely expressed in all tissues, with higher expression levels detected in the brain. DNAJB6 is involved in diverse cellular functions ranging from murine placental development, reducing the formation and toxicity of mis-folded protein aggregates, to self-renewal of neural stem cells. Involvement of DNAJB6 is implicated in multiple pathologies such as Huntington's disease, Parkinson's diseases, limb-girdle muscular dystrophy, cardiomyocyte hypertrophy and cancer. This review summarizes the important involvement of the spliced isoforms of DNAJB6 in various pathologies with a specific focus on the emerging roles of human DNAJB6 in cancer and the underlying molecular mechanisms.

Changes in the expression of genes involved in the ovarian function of rats caused by daily exposure to 3-methylcholanthrene and their prevention by α-naphthoflavone

Daily exposure to low doses of 3-methylcholanthrene (3MC) during the pubertal period in rats disrupts both follicular growth and ovulation. Thus, to provide new insights into the toxicity mechanism of 3MC in the ovary, here we investigated the effect of daily exposure to 3MC on selected ovarian genes, the role of the aryl hydrocarbon receptor (AhR) and the level of epigenetic remodeling of histone post-transcriptional modifications. Immature rats were daily injected with 3MC (0.1 or 1 mg/kg) and mRNA expression of genes involved in different ovarian processes were evaluated. Of the 29 genes studied, 18 were up-regulated, five were down-regulated and six were not altered. To assess whether AhR was involved in these changes, we used the chromatin immunoprecipitation assay. 3MC increased AhR binding to promoter regions of genes involved in Notch signaling (Hes1, Jag1), activation of primordial follicles (Cdk2), cell adhesion (Icam1), stress and tumor progression (Dnajb6), apoptosis (Bax, Caspase-9) and expression of growth and transcription factors (Igf2, Sp1). Studying the trimethylation and acetylation of histone 3 (H3K4me3 and H3K9Ac, respectively) of these genes, we found that 3MC increased H3K4me3 in Cyp1a1, Jag1, Dnajb6, Igf2, Notch2, Adamts1, Bax and Caspase-9, and H3K9Ac in Cyp1a1, Jag1, Cdk2, Dnajb6, Igf2, Icam1, and Sp1. Co-treatment with α-naphthoflavone (αNF), a specific antagonist of AhR, prevented almost every 3MC-induced changes. Despite the low dose used in these experiments, daily exposure to 3MC induced changes in both gene expression and epigenomic remodeling, which may lead to premature ovarian failure.

Nuclear Localization of DNAJB6 Is Associated With Survival of Patients With Esophageal Cancer and Reduces AKT Signaling and Proliferation of Cancer Cells

BACKGROUND & AIMS

The DnaJ (Hsp40) homolog, subfamily B, member 6 (DNAJB6) is part of a family of proteins that regulates chaperone activities. One of its isoforms, DNAJB6a, contains a nuclear localization signal and regulates β-catenin signaling during breast cancer development. We investigated the role of DNAJB6 in the pathogenesis of esophageal squamous cell carcinoma (ESCC).

METHODS

We performed immunohistochemical analyses of primary ESCC samples and lymph node metastases from a cohort of 160 patients who underwent esophagectomy with no preoperative chemoradiotherapy at Hong Kong Queen Mary Hospital. Data were collected on patient outcomes over a median time of 12.1 ± 2.9 months. Retrospective survival association analyses were performed. Wild-type and mutant forms of DNAJB6a were overexpressed in cancer cell lines (KYSE510, KYSE 30TSI, KYSE140, and KYSE70TS), which were analyzed in proliferation and immunoblot assays, or injected subcutaneously into nude mice. Levels of DNAJB6 were knocked down in ESCC cell lines (KYSE450 and T.Tn), immortalized normal esophageal epithelial cell lines (NE3 and NE083), and other cells with short hairpin RNAs, or by genome engineering. Bimolecular fluorescence complementation was used to study interactions between proteins in living cells.

RESULTS

In primary ESCC samples, patients whose tumors had high nuclear levels of DNAJB6 had longer overall survival times (19.2 ± 1.8 months; 95% confidence interval [CI], 15.6-22.8 mo) than patients whose tumors had low nuclear levels of DNAJB6 (12.6 ± 1.4 mo; 95% CI, 9.8-15.4 mo; P = .004, log-rank test). Based on Cox regression analysis, patients whose tumors had high nuclear levels of DNAJB6 had a lower risk of death than patients with low levels (hazard ratio, 0.562; 95% CI, 0.379-0.834; P = .004). Based on log-rank analysis and Cox regression analysis, the combination of the nuclear level of DNAJB6 and the presence of lymph node metastases at diagnosis could be used to stratify patients into groups with good or bad outcomes (P < .0005 for both analyses). There was a negative association between the nuclear level of DNAJB6 and the presence of lymph node metastases (P = .022; Pearson χ(2) test). Cancer cell lines that overexpressed DNAJB6a formed tumors more slowly in nude mice than control cells or cells that expressed a mutant form of DNAJB6a that did not localize to the nucleus. DNAJB6 knockdown in cancer cell lines promoted their growth as xenograft tumors in mice. A motif of histidine, proline, and aspartic acid in the J domain of DNAJB6a was required for its tumor-suppressive effects and signaling via AKT1. Loss of DNAJB6a resulted in up-regulation of AKT signaling in cancer cell lines and immortalized esophageal epithelial cells. Expression of a constitutively active form of AKT1 restored proliferation to tumor cells that overexpressed DNAJB6a, and DNAJB6a formed a complex with AKT1 in living cells. The expression of DNAJB6a reduced the sensitivity of ESCC to AKT inhibitors; the expression level of DNAJB6a affected AKT signaling in multiple cancer cell lines.

CONCLUSIONS

Nuclear localization of DNAJB6 is associated with longer survival times of patients with ESCC. DNAJB6a reduces AKT signaling, and DNAJB6 expression in cancer cells reduces their proliferation and growth of xenograft tumors in mice. DNAJB6a might be developed as a biomarker for progression of ESCC.

CSE1L Links cAMP/PKA and Ras/ERK pathways and regulates the expressions and phosphorylations of ERK1/2, CREB, and MITF in melanoma cells

The Ras/ERK (extracellular signal-regulated protein kinase) and cAMP/PKA (protein kinase A) pathways are essential for the transcriptional activities of CREB (cAMP response element binding protein) and MITF (microphthalmia-associated transcription factor) in melanogenesis and the progression of melanoma. However, the interaction between Ras/ERK and cAMP/PKA pathways in the melanogenesis and progression of melanoma is not fully known. Here, we report that CSE1L (chromosome segregation 1-like protein) regulates cAMP/PKA-induced CREB and MITF expressions as well as Ras-induced ERK1/2 phosphorylation. IBMX, a cAMP/PKA activator, treatment induced CSE1L phosphorylation and augmented Ras-induced ERK1/2 phosphorylation. CSE1L knockdown by CSE1L shRNA expression vectors inhibited Ras-induced ERK1/2 phosphorylation and melanogenesis in melanoma cells. CSE1L overexpression increased phospho-CREB expression; CSE1L knockdown also inhibited Ras-induced phospho-CREB, MITF, and tyrosinase expressions, regardless of the presence of IBMX. This study identifies CSE1L links and controls the Ras/ERK and cAMP/PKA pathways in the melanogenesis of melanoma cells. Melanomas frequently develop drug resistance via paradoxical activation of Ras/Raf/MEK/ERK or alternatively activated Ras/ERK and cAMP/PKA pathways. Thus CSE1L may be a potential target for treating melanomas that harbor Ras mutations or are resistant to drugs targeting Raf/MEK/ERK. © 2015 Wiley Periodicals, Inc.