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Knockdown of cullin 4A inhibits growth and increases chemosensitivity in lung cancer cells.

Cullin 4A (Cul4A) has been observed to be overexpressed in various cancers. In this study, the role of Cul4A in the growth and chemosensitivity in lung cancer cells were studied. We showed that Cul4A is overexpressed in lung cancer cells and tissues. Knockdown of the Cul4A expression by shRNA in lung cancer cells resulted in decreased cellular proliferation and growth in lung cancer cells. Increased sensitivity to gemcitabine, a chemotherapy drug, was also noted in those Cul4A knockdown lung cancer cells. Moreover, increased expression of p21, transforming growth factor (TGF)‐β inducible early gene‐1 (TIEG1) and TGF beta‐induced (TGFBI) was observed in lung cancer cells after Cul4A knockdown, which may be partially related to increased chemosensitivity to gemcitabine. G0/G1 cell cycle arrest was also noted after Cul4A knockdown. Notably, decreased tumour growth and increased chemosensitivity to gemcitabine were also noted after Cul4A knockdown in lung cancer xenograft nude mice models. In summary, our study showed that targeting Cul4A with RNAi or other techniques may provide a possible insight to the development of lung cancer therapy in the future.

Favorable clinical outcome and unique characteristics in association with Twist1 overexpression in de novo acute myeloid leukemia

Epithelial–mesenchymal transition (EMT) is a critical process for inducing stem-like properties of epithelial cancer cells. However, the role of EMT inducers in hematological malignancies is unknown. Twist1, an EMT inducer necessary for cell migration, has recently been found to have transcriptionally regulatory activity on the expression of Bmi1, and these two are capable of promoting tumorigenesis in a synergized manner. Knowing that Bmi1 expression is essential for maintenance of leukemic stem cells, we speculate that Twist1 might govern the pathogenesis of acute myeloid leukemia (AML) development as well. We found that upregulated Twist1 increased Bmi1 expression in AML and endued leukemic cells a higher proliferative potential and increased resistance to apoptosis. In primary AML samples, there was strong positive correlation between the expression levels of Twist1 and Bmi1. AML patients whose leukemic blasts harbored overexpressed Twist1 had a more aggressive clinical phenotype, but they were more likely to have a better clinical outcome after standard therapy. In vitro studies confirmed that Twist1-overexpressing leukemic cells were more susceptible to cytarabine, but not daunorubicin, cytotoxicity. Our findings suggest that, in a subset of AML patients, Twist1 has a prominent role in the pathogenesis of the disease that leads to unique clinical phenotypes.

Clinical characteristics and treatment outcome in a Taiwanese population of patients with Epstein-Barr virus-positive diffuse large B-cell lymphoma.

OBJECTIVE Epstein-Barr virus-positive diffuse large B-cell lymphoma is a provisional entity in the 2008 World Health Organization classification of tumors of hematopoietic and lymphoid tissues. Reports on the characteristics and clinical outcome of this disease in different geographic regions showed great disparities. METHODS To define the clinical characteristics as well as the prognostic impact of Epstein-Barr virus infection on diffuse large B-cell lymphoma in Taiwan, we retrospectively investigated the Epstein-Barr virus status of 89 patients with newly diagnosed diffuse large B-cell lymphoma in our institute. RESULTS Using a cutoff point of positive nuclear staining of Epstein-Barr virus-encoded RNA-1-in situ hybridization in ≥20% of the examined cells, we identified 15 cases (16.9%) of the entire study cohort as Epstein-Barr virus-positive diffuse large B-cell lymphoma. The clinical and laboratory features were not different between Epstein-Barr virus-positive and -negative diffuse large B-cell lymphoma patients. Univariate analysis showed patients with diffuse large B-cell lymphoma that were either Epstein-Barr virus-positive or had activated B-cell-like features had an inferior overall survival. Older age, advanced stage and lymphoma with activated B-cell-like features or Epstein-Barr virus-encoded RNA positivity were independent prognostic factors affecting overall survival on multivariate analysis. Patients with two or three of these adverse-risk factors were considered high risk and fared far worse than patients with no or only one adverse factor. CONCLUSIONS Taken together, we demonstrated that a higher frequency of Epstein-Barr virus association was detected in a Taiwanese cohort of diffuse large B-cell lymphoma patients, and Epstein-Barr virus-encoded RNA positivity was shown to add important prognostic value in these patients.

Expression of Beclin Family Proteins Is Associated with Tumor Progression in Oral Cancer

Background Beclin 1 and Beclin 2 are autophagy-related proteins that show similar amino acid sequences and domain structures. Beclin 1 established the first connection between autophagy and cancer. However, the role of Beclin 2 in cancer is unclear. The aims of this study were to analyze Beclin 1 and Beclin 2 expressions in oral cancer tissues and in cell lines, and to evaluate their possible roles in cancer progression. Methods We investigated Beclin 1 and Beclin 2 expressions by immunohistochemistry in 195 cases of oral cancer. The prognostic roles of Beclin 1 and Beclin 2 were analyzed statistically. In vitro, overexpression and knockdown of Beclin proteins were performed on an oral cancer cell line, SAS. The immunofluorescence and autophagy flux assays confirmed that Beclin proteins were involved in autophagy. The impacts of Beclin 1 and Beclin 2 on autophagy and tumor growth were evaluated by conversion of LC3-I to LC3-II and by clonogenic assays, respectively. Results Oral cancer tissues exhibited aberrant expressions of Beclin 1 and Beclin 2. The cytoplasmic Beclin 1 and Beclin 2 expressions were unrelated in oral cancer tissues. In survival analyses, high cytoplasmic Beclin 1 expression was associated with low disease specific survival, and negative nuclear Beclin 1 expression was associated with high recurrent free survival. Patients with either high or low cytoplasmic Beclin 2 expression had significantly lower overall survival and disease specific survival rates than those with moderate expression. In oral cancer cells, overexpression of either Beclin 1 or Beclin 2 led to autophagy activation and increased clonogenic survival; knockdown of Beclin 2 impaired autophagy and increased clonogenic survival. Conclusions Our results indicated that distinct patterns of Beclin 1 and Beclin 2 were associated with aggressive clinical outcomes. Beclin 1 overexpression, as well as Beclin 2 overexpression and depletion, contributed to tumor growth. These findings suggest Beclin proteins are associated with tumorigenesis.

A sensitive and high throughput TaqMan-based reverse transcription quantitative polymerase chain reaction assay efficiently discriminates ALK rearrangement from overexpression for lung cancer FFPE specimens.

OBJECTIVES ALK fusion gene is an oncogenic driver in lung cancer with low prevalence, which can be ameliorated by crizotinib. Currently, ALK fusion gene can be diagnosed by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC), but inconstistnt results between the two methods are encountered regularly. To make the ALK fusion gene screening more efficient and to provide a simple solution to clarify the discrepancy between FISH and IHC results, a sensitive TaqMan-based reverse transcription quantitative polymerase chain reaction (RT-qPCR) assay was established. MATERIALS AND METHODS The 3-plex TaqMan-based RT-qPCR assay was established and performed on 102 archived formalin-fixed, paraffin-embedded (FFPE) NSCLC samples to detect ALK rearrangement and overexpression. Break-apart FISH and automatic immunohistochemistry based ALK assays were performed side by side using tissue microarray. RESULTS The RT-qPCR was performed successfully for 80 samples and 10 of them showed positive signals. Three out of the 10 qPCR positive cases were further confirmed by FISH and IHC test. Two others were IHC positive and FISH negative, and expressed full-length ALK transcript. The rest were neither FISH nor IHC positive and their ALK expression level was significantly lower than those FISH or IHC positive cases. CONCLUSION Our RT-qPCR assay demonstrates that the capability and reliability of ALK detection is comparable to FISH and IHC, but it is more effective at discriminating ALK rearrangement from overexpression. The RT-qPCR assay easily clarifies the discrepancy between FISH and IHC, and can be incorporated into routine ALK screening for lung cancer.

Epidermal Growth Factor Receptor Mutation Enhances Expression of Cadherin-5 in Lung Cancer Cells.

Epidermal growth factor receptor (EGFR) activation has been shown to play a critical role in tumor angiogenesis. In this study, we investigate the correlation between EGFR mutations and cadherin-5 (CDH5), which is an angiogenic factor, in lung cancer cells. Increased expression CDH5 is observed in lung cancer cells with EGFR mutations. Stable lung cancer cell lines expressing mutant (exon 19 deletion E746-A750, and exon 21 missense mutation L858R) and wild type EGFR genes are established. A significantly higher expression of CDH5 is observed in exon 19 deletion stable lung cancer cells and mouse xenografts. Further studies show that expression of CDH5 is decreased after the inhibition of EGFR and downstream Akt pathways in lung cancer cells with EGFR mutation. In addition, mutant EGFR genes potentiates angiogenesis in lung cancer cells, which is inhibited by CDH5 siRNA, and potentiates migration and invasion in lung cancer cells. Our study shows that mutant EGFR genes are associated with overexpression of CDH5 through increased phosphorylation of EGFR and downstream Akt pathways. Our result may provide an insight into the association of mutant EGFR and CDH5 expression in lung cancer and aid further development of target therapy for NSCLC in the future.

Aberrant let7a/HMGA2 signaling activity with unique clinical phenotype in JAK2-mutated myeloproliferative neoplasms

High mobility group AT-hook 2 (HMGA2) is an architectural transcription factor that is negatively regulated by let-7 microRNA through binding to it’s 3′-untranslated region. Transgenic mice expressing Hmga2 with a truncation of its 3′-untranslated region has been shown to exhibit a myeloproliferative phenotype. To decipher the let-7-HMGA2 axis in myeloproliferative neoplasms, we employed an in vitro model supplemented with clinical correlation. Ba/F3 cells with inducible JAK2V617F expression (Ton.JAK2.V617F cells) showed upregulation of HMGA2 with concurrent let-7a repression. Ton.JAK2.V617F cells treated with a let-7a inhibitor exhibited further escalation of Hmga2 expression, while a let-7a mimic diminished the Hmga2 transcript level. Hmga2 overexpression conferred JAK2-mutated cells with a survival advantage through inhibited apoptosis. A pan-JAK inhibitor, INC424, increased the expression of let-7a, downregulated the level of Hmga2, and led to increased apoptosis in Ton.JAK2.V617F cells in a dose-dependent manner. In samples from 151 patients with myeloproliferative neoplasms, there was a modest inverse correlation between the expression levels of let-7a and HMGA2. Overexpression of HMGA2 was detected in 29 (19.2%) of the cases, and it was more commonly seen in patients with essential thrombocythemia than in those with polycythemia vera (26.9% vs. 12.7%, P=0.044). Patients with upregulated HMGA2 showed an increased propensity for developing major thrombotic events, and they were more likely to harbor one of the 3 driver myeloproliferative neoplasm mutations in JAK2, MPL and CALR. Our findings suggest that, in a subset of myeloproliferative neoplasm patients, the let-7-HMGA2 axis plays a prominent role in the pathogenesis of the disease that leads to unique clinical phenotypes.

Enhanced Risk for Specific Somatic Myeloproliferative Neoplastic Mutations in Patients with Stroke

BACKGROUND Somatic mutations of Janus kinase 2 (JAK2V617F), calreticulin (CALR), and myeloproliferative leukemia virus oncogene (MPL) are the major clonal molecules that drive the pathogenesis of myeloproliferative neoplasms (MPN). It is well recognized that MPN patients carry an excessive risk of thrombohemorrhagic complications. However, little is known about the prevalence of these clonal markers in patients with cerebral vascular disease. METHODS To address this issue, 153 consecutive stroke patients in Taiwan were enrolled in the study. Allele-specific PCR (AS-PCR), real-time AS-PCR, and Illumina paired-end sequencing were employed to detect the presence of MPL, JAK2V617F, and CALR exon 9 mutations, respectively. RESULTS JAK2V617F mutation was detectable in 13 samples (8.5%), but the allele burdens (AB) were greater than 1% in only six (3.9%) of them. Compared to JAK2-unmutated patients, those with JAK2V617F AB > 1% had significantly higher white blood count (p = 0.01), although four of the six did not exhibit MPN phenotypes. Two patients had a heterozygous CALR exon9 mutation locating outside the coding region and did not alter the amino acid sequence of this protein. On the other hand, there were no patients carrying the MPL mutations. Using patient age, baseline hemogram, and stroke-relevant risk factors, we developed a predictive model that could successfully identify stroke patients at risk of carrying clonal JAK2V617F mutation. CONCLUSION The prevalence of JAK2V617F mutation in stroke patients was higher than that seen in general population. Based on our newly developed probability stratification model, genotyping of JAK2V617F mutation in selected patients with stroke might be warranted.

Mutant DNMT3A clone evading chemotherapy and infiltrating central nervous system in a patient with molecularly good-risk acute myeloid leukemia.

Dear Editor,Approximately45%ofacutemyeloidleukemia(AML)shownormal karyotype (cytogenetically normal AML (CN-AML))at diagnosis, which are cytogenetically categorized as inter-mediate risk but is clinically heterogenous. The evaluation ofmolecular mutations offers better prognostication for CN-AML patients. Here, we present a case of molecularly good-risk CN-AML who unusually manifested central nervoussystem disease at the time of first remission.A 51-year-old lady was diagnosed with CN-AML (M2)with favorable-risk molecular profile: mutant NPM1,wild-typeMLL-PTD,andnegativeFLT3-ITD.Shereceivedinduc-tionchemotherapywithdaunorubicin(90mg/m

Quantitative competitive allele-specific TaqMan duplex PCR (qCAST-Duplex PCR) assay: a refined method for highly sensitive and specific detection of JAK2V617F mutant allele burdens

JAK2V617F mutation is one of the key driver mutations in myeloproliferative neoplasms (MPN). Since its discovery, many diagnostic techniques have been applied in its detection. Unfortunately, there were significant discrepancies in the allele burden (AB) quantification when blinded samples were tested in a multicenter study. The study also concluded by delineating the importance of using well-defined, accurate standards to refine JAK2 quantitative assays. Although DNA from JAK2-mutated UKE-1 and HEL cells are commonly used for this purpose, none of these cells are considered ideal, as the HEL cells carry multiple copies of JAK2, and UKE-1 cells do undergo clonal evolution with increasing JAK2 copies during in vitro cultures. To improve the accuracy of JAK2V617F detection and quantification, we made some refinements to the allelespecific real-time polymerase chain reaction (qPCR) assay and created a novel method. Firstly, we decided to select JAK2 exon 21 as our reference control (Figure 1A). It improved the efficacy of copy number normalization by directly calibrating equal copies of target DNA with the reference control within the same gene. In the second step, the exon 21 control sequence, along with either one of the target regions [JAK2 wild-type (WT) and V617F mutant], were cloned into a yT&A cloning vector (Yeastern Biotech, Taiwan) to generate two standard plasmids (JAK2_WT_Ctrl_yT&A and JAK2_V617F_Ctrl_yT&A, representing 0% and 100% mutant AB, respectively) (Figure 1B). The plasmid pair had the same size (3306 bps) and could be easily manipulated with identical copy numbers. They were used to establish quantification standards. Thirdly, allele-specific (AS) primers and a FAM-containing TaqMan probe (Bio-