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 ß-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.

Prognostic MicroRNA Fingerprints Predict Recurrence of Early-Stage Hepatocellular Carcinoma Following Hepatectomy.

Purpose: This study aims to develop liquid biopsy assays for early HCC diagnosis and prognosis. Methods: Twenty-three microRNAs were first consolidated as a panel (HCCseek-23 panel) based on their reported functions in HCC development. Serum samples were collected from 103 early-stage HCC patients before and after hepatectomy. Quantitative PCR and machine learning random forest models were applied to develop diagnostic and prognostic models. Results: For HCC diagnosis, HCCseek-23 panel demonstrated 81% sensitivity and 83% specificity for identifying HCC in the early-stage; it showed 93% sensitivity for identifying alpha-fetoprotein (AFP)-negative HCC. For HCC prognosis, the differential expressions of 8 microRNAs (HCCseek-8 panel: miR-145, miR-148a, miR-150, miR-221, miR-223, miR-23a, miR-374a, and miR-424) were significantly associated with disease-free survival (DFS) (Log-rank test p-value = 0.001). Further model improvement using these HCCseek-8 panel in combination with serum biomarkers (i.e. AFP, ALT, and AST) demonstrated a significant association with DFS (Log-rank p-value = 0.011 and Cox proportional hazards analyses p-value = 0.002). Conclusion: To the best of our knowledge, this is the first report to integrate circulating miRNAs, AST, ALT, AFP, and machine learning for predicting DFS in early HCC patients undergoing hepatectomy. In this setting, HCCSeek-23 panel is a promising circulating microRNA assay for diagnosis, while HCCSeek-8 panel is promising for prognosis to identify early HCC recurrence.

Tumor suppressor dual-specificity phosphatase 6 (DUSP6) impairs cell invasion and epithelial-mesenchymal transition (EMT)-associated phenotype.

Suppressive effects of DUSP6 in tumorigenesis and EMT-associated properties were observed. Dual-specificity phosphatase (DUSP6) is a MAP kinase phosphatase (MKP) negatively regulating the activity of ERK, one of the major molecular switches in the MAPK signaling cascade propagating the signaling responses during malignancies. The impact of DUSP6 in EMT and its contribution to tumor dissemination has not yet been characterized. Due to differences in tumor microenvironments affecting cell signaling during cancer progression, DUSP6 may play varying roles in tumor development. We sought to examine the potential role of DUSP6-mediated tumorigenesis and EMT-associated properties in two aerodigestive tract cancers, namely, esophageal squamous cell carcinoma (ESCC) and nasopharyngeal carcinoma (NPC). Significant loss of DUSP6 was observed in 100% of 11 ESCC cell lines and 71% of seven NPC cell lines. DUSP6 expression was down-regulated in 40% of 30 ESCC tumor tissues and 75% of 20 NPC tumor tissues compared to their respective normal counterparts. Suppressive effects of DUSP6 in tumor formation and cancer cell mobility are seen in in vivo tumorigenicity assay and in vitro colony formation, three-dimensional Matrigel culture, cell migration and invasion chamber tests. Notably, overexpression of DUSP6 impairs EMT-associated properties. Furthermore, tissue microarray analysis reveals a clinical association of DUSP6 expression with better patient survival. Taken together, our study provides a novel insight into understanding the functional impact of DUSP6 in tumorigenesis and metastasis of ESCC and NPC.

Hallmark microRNA signature in liquid biopsy identifies hepatocellular carcinoma and differentiates it from liver metastasis.

Purpose: This study aims to develop a liquid biopsy assay to identify HCC and differentially diagnose hepatocellular carcinoma (HCC) from colorectal carcinoma (CRC) liver metastasis. Methods: Thirty-two microRNAs ("HallMark-32" panel) were designed to target the ten cancer hallmarks in HCC. Quantitative PCR and supervised machine learning models were applied to develop an HCC-specific diagnostic model. One hundred thirty-three plasma samples from intermediate-stage HCC patients, colorectal cancer (CRC) patients with liver metastasis, and healthy individuals were examined. Results: Six differentially expressed microRNAs ("Signature-Six" panel) were identified after comparing HCC and healthy individuals. The microRNA miR-221-3p, miR-223-3p, miR-26a-5p, and miR-30c-5p were significantly down-regulated in the plasma of HCC samples, while miR-365a-3p and miR-423-3p were significantly up-regulated. Machine learning models combined with HallMark-32 and Signature-Six panels demonstrated promising performance with an AUC of 0.85-0.96 (p ≤ 0.018) and 0.84-0.93 (p ≤ 0.021), respectively. Further modeling improvement by adjusting sample quality variation in the HallMark-32 panel boosted the accuracy to 95% ± 0.01 and AUC to 0.991 (95% CI 0.96-1, p = 0.001), respectively. Even in alpha fetoprotein (AFP)-negative (< 20ng/mL) HCC samples, HallMark-32 still achieved 100% sensitivity in identifying HCC. The Cancer Genome Atlas (TCGA, n=372) analysis demonstrated a significant association between HallMark-32 and HCC patient survival. Conclusion: To the best of our knowledge, this is the first report to utilize circulating miRNAs and machine learning to differentiate HCC from CRC liver metastasis. In this setting, HallMark-32 and Signature-Six are promising non-invasive tests for HCC differential diagnosis and distinguishing HCC from healthy individuals.

Identification of an invasion and tumor-suppressing gene, Endoglin (ENG), silenced by both epigenetic inactivation and allelic loss in esophageal squamous cell carcinoma.

Endoglin (ENG) has been identified as a candidate tumor-suppressor gene in esophageal squamous cell carcinoma (ESCC). Earlier microcell-mediated chromosome transfer (MMCT) studies of chromosome 9 in ESCC narrowed down a tumor-suppressive critical region to 9q33-34. ENG maps to 9q34-qter and encodes a transformation growth factor beta (TGFbeta) superfamily auxiliary receptor. This study aims to identify the potential role for ENG in ESCC development. Significant downregulation of ENG was detected at frequencies of 87.5% in 16 ESCC cell lines, 39.1% directly in 23 ESCC tumor specimens from Hong Kong, and 33.4% in 18 ESCC tumor specimens from the high-risk ESCC region of Henan, China. By methylation-specific PCR, methylated sequences were detected in an ESCC cell line panel and in clinical specimens. Following demethylation treatment in 9 ESCC cell lines, ENG expression was obviously restored. Loss of heterozygosity (LOH) in a 4.7 Mb region on 9q32-q34, where ENG maps, was observed directly in ESCC tumor tissues. Both epigenetic methylation and allelic loss appear to contribute to ENG downregulation in tumor cells. In vitro and in vivo functional studies such as colony formation, Matrigel culture, invasion and tumorigenicity assays were performed. Colony formation efficiency was significantly reduced by overexpression of ENG. In addition, significantly smaller colonies of ENG stable transfectants were formed in Matrigel culture. Significant suppression of invasion efficiency and tumorigenicity were also observed, when comparing the ENG stable transfectants with the vector-alone transfectants. This study provides evidence supporting ENG, as a cell invasion and tumor-suppressing gene in ESCC.

Frequent decreased expression of candidate tumor suppressor gene, DEC1, and its anchorage-independent growth properties and impact on global gene expression in esophageal carcinoma.

Previous studies showed that expression of the novel candidate tumor suppressor gene, DEC1 (Deleted in Esophageal Cancer 1), is reduced in esophageal carcinoma and suppresses cancer cell growth in vitro and tumor growth in vivo in nude mice. This study shows that DEC1 gene expression was downregulated in 100% of 16 esophageal squamous cell carcinoma (ESCC) cell lines and 52 and 45%, respectively, of esophageal tumor specimens from Hong Kong and a high-risk ESCC region of Henan, China. Using epitope tagging, the DEC1 protein was localized to both the cytoplasm and nucleus of the cell. In 3D Matrigel culture, no significant difference in colony numbers formed was observed for DEC1 stable transfectants, as compared to vector-alone transfectant controls. However, significantly smaller colony sizes were observed for the DEC1 transfectants. In in vitro cell migration, invasion and soft agar assays of DEC1 transfectants, only the soft agar assay showed statistically significant differences in colony numbers with the vector-alone controls, indicating that DEC1 may be involved in anchorage-independent cell growth. In addition, the global gene expression affected by DEC1 in tumor-suppressive stable transfectants was investigated using cDNA oligonucleotide microarray hybridization. Three candidate genes, TFPI-2, GDF15 and DUSP6, were identified through this approach; they are downregulated in tumor segregants of DEC1 stable transfectants, ESCC cell lines and esophageal tumors and have a potential role in tumor growth and progression. These studies show that DEC1 is involved in esophageal cancer development and help elucidate its functional role in tumor development.

Nuclear EGFR and Integrator/Super Elongation Complex concurrently binds to Immediate Early Genes for gene transactivation.

The gene transactivation function of nuclear EGFR (nEGFR) has been studied by investigating the genomic co-occupancies of nEGFR and RNA Polymerase II (RNAPII). However, due to RNAPII pausing, the co-recruitment of RNAPII and nEGFR does not necessarily represent productive transactivation. In this study, we integrated gatekeepers of productive transcriptional elongation such as Integrator and Super Elongation Complex (SEC) to interrogate the function of nEGFR. By analyzing publicly available ChIP-seq and RNA-seq data, we aims to 1) explore the function of nEGFR, 2) unravel nEGFR target genes, and 3) discuss potential mechanisms of nEGFR chromatin recruitment. EGF treatment in HeLa cells instigated chromatin recruitment of nEGFR, ERK, RNAPII, Integrator, and SEC in a cluster of 61 EGF-responsive genes. The function of nEGFR was identified as gene-activating rather than gene-repressing. Within the cluster of EGF-responsive genes, nEGFR targeted eleven Immediate Early Genes (IEGs) - JUN, EGR1, JUNB, IER2, KLF2, FOS, FOSL1, RHOB, CCNL1, DUSP2, and DUSP5, which up-regulated >2-fold after EGF stimulation. The promoter of these target genes commonly harbors AT-rich minimal consensus sequences for nEGFR binding. In addition, TCGA data analysis demonstrated positive correlations between EGFR and JUN/FOSL1/RHOB expressions, as well as clinical correlations in specific cancer types. To our knowledge, this is the first study to compare the genome-wide distribution of nEGFR versus Integrator and SEC, providing novel insight into supporting the gene-activating function of nEGFR. We revealed a panel of eleven nEGFR target genes, which concurrently recruited nEGFR, RNAPII, Integrator, and SEC for productive transcriptional elongation.

Succinct workflows for circulating tumor cells after enrichment: From systematic counting to mutational profiling.

PURPOSE: This study aims to establish a highly adaptable workflow downstream of microfluidic enrichment for facilitating systematic CTC enumeration and genetic discovery. METHODS: To facilitate CTC enumeration, we established a CK/EPCAM-combined immunostaining strategy and an automated CTC analytical pipeline using an open-source image analyzer. By virtue of this workflow, we conducted a pilot study of 56 cancer patients and 21 healthy individuals using a high-throughput spiral microfluidic chip system. To facilitate genetic discovery of somatic mutations in CTCs, we integrated the CTC enumeration into next-generation sequencing and established a straightforward amplicon library comprising diversifier random sequences to sequence CTC samples. RESULTS: The CTC staining and enumeration workflow achieved 80.4% sensitivity and 85.7% specificity (AUC = 0.87, p = 0.004, power = 0.985), as evaluated by ROC analysis. Univariate and multivariate analysis verified that the CTC (CK/EpCAM+CD45-), but not other cell populations, is a significant and independent biomarker for cancer patients (p < 0.01). Serial CTC monitoring of the patients revealed reduction in CTC numbers after treatments, suggesting its clinical utility in pharmacodynamic studies. Deep sequencing of CTC samples revealed somatic mutations in TP53 and ESR1. CONCLUSIONS: The significance of this report is to demonstrate a systematic and adaptable workflow to bridge the gap between the microfluidic enrichment and CTC analyses, which fosters broader applications of CTCs in both clinical settings and academic studies.

S-phase sensing of DNA-protein crosslinks triggers TopBP1-independent ATR activation and p53-mediated cell death by formaldehyde.

We examined genotoxic signaling and cell fate decisions in response to a potent DNA-protein crosslinker formaldehyde (FA). DNA-protein crosslinks (DPC) are poorly understood lesions produced by bifunctional carcinogens and several cancer drugs. FA-treated human cells showed a rapid activation of ATR kinase that preferentially targeted the p53 transcription factor at low doses and CHK1 kinase at more severe damage, producing bell-shaped and sublinear responses, respectively. CHK1 phosphorylation was transient, and its loss was accompanied by increased p53 accumulation and Ser15 phosphorylation. Activation of p53 was insensitive to inhibition of mismatch repair and nucleotide and base excision repair, excluding the role of small DNA adducts in this response. The p53-targeted signaling was transcription-independent, absent in quiescent cells and specific to S-phase in cycling populations. Unlike other S-phase stressors, FA-activated p53 was functional transcriptionally, promoted apoptosis in lung epithelial cells and caused senescence in normal lung fibroblasts. FA did not induce ATR, RAD1 or RPA foci, and p53 phosphorylation was TopBP1-independent, indicating a noncanonical mode of ATR activation. Replication arrest by FA caused a dissociation of ATR from a chromatin-loaded MCM helicase but no PCNA monoubiquitination associated with stalled polymerases. These results suggest that unlike typical DNA adducts that stall DNA polymerases, replication inhibition by bulkier DPC largely results from blocking upstream MCM helicase, which prevents accumulation of ssDNA. Overall, our findings indicate that S-phase-specific, TopBP1-independent activation of the ATR-p53 axis is a critical stress response to FA-DPC, which has implications for understanding of FA carcinogenesis.

LTBP-2 confers pleiotropic suppression and promotes dormancy in a growth factor permissive microenvironment in nasopharyngeal carcinoma.

This study identified LTBP-2 as a pleiotropic tumor suppressor in nasopharyngeal carcinoma, which safeguards against critical malignant behaviors of tumor cells. LTBP-2 expression was significantly decreased or lost in up to 100% of NPC cell lines (7/7) and 80% of biopsies (24/30). Promoter hypermethylation was found to be involved in LTBP-2 silencing. Using a tetracycline-regulated inducible expression system, we unveiled functional roles of LTBP-2 in suppressing colony formation, anchorage-independent growth, cell migration, angiogenesis, VEGF secretion, and tumorigenicity. Three-dimensional culture studies suggested the involvement of LTBP-2 in maintenance of tumor cell dormancy in a growth factor favorable microenvironment.