Firm productivity gains in a period of slow trade liberalization: evidence from Brazil.

Existing literature recognizes the possible role of trade policy and firms' exposure to international trade as determinants of productivity. A strand of the literature sheds light on the effects of trade policy changes on firm-level productivity. Another strand studies the relationship between firms' trade status (exporting production or importing intermediates, but usually not both simultaneously) and firm-level TFP dynamics. However, the analyses that integrate both strands are scarce. This paper aims to disentangle the impact of input and output tariffs on firms' productivity. Further, it analyses whether the impact of changes in tariffs is conditioned by the trade status of the firm (exporting and/or importing). At difference to most previous papers, we carry out our analysis for a large developing country in a period of slow trade liberalization. Thus, in the empirical part, we use data from firms belonging to Brazilian industrial sectors (manufacturing and mining) during 2000-2008. After estimating total factor productivity (TFP) at the firm level using updated methodologies, we estimate both the impact of trade policy and firms' trade status on TFP dynamics. Our results suggest that trade liberalization (through reductions in input or output tariffs) increases TFP, being the effect associated to a reduction in input tariffs greater. Furthermore, the impact of trade policy on TFP spreads among all firms, which could be consistent with the existence of spillovers from trading firms to non-trading firms or with the notion that trade liberalization exerts competitive pressure on all firms, regardless of their initial exposure to international trade. Finally, we also find evidence of a positive effect of both the import and export statuses on TFP.

Methylation status of Wnt signaling pathway genes affects the clinical outcome of Philadelphia-positive acute lymphoblastic leukemia.

The clinical significance of aberrant promoter methylation of the canonical Wnt pathway antagonist genes (sFRP1, sFRP2, sFRP4, sFRP5, Wif1, Dkk3, and Hdpr1) and also putative tumor-suppressor gene Wnt5a, belonging to the non-canonical Wnt signaling pathway, was investigated in a large series of 75 patients with Philadelphia chromosome-positive acute lymphoblastic leukemia by methylation-specific polymerase chain reaction. At least one methylated gene was observed in cells from 66% (49/75) of patients (methylated group). Disease-free survival and overall survival at 9 years were 51 and 40%, respectively, for the unmethylated group and 3 and 2%, respectively, for the methylated group (both P < 0.0001). Multivariate analysis demonstrated that the Wnt methylation profile was an independent prognostic factor predicting disease-free survival (P = 0.007) and overall survival (P = 0.039). Abnormal DNA methylation of promoter-associated CpG islands in the Wnt signaling pathway is very common in Philadelphia chromosome-positive acute lymphoblastic leukemia and potentially defines subgroups with distinct clinical characteristics.

Repetitive DNA hypomethylation in the advanced phase of chronic myeloid leukemia.

Repetitive elements are heavily methylated in normal tissues, but hypomethylated in malignant tissues, driving the global genomic hypomethylation found in cancer. This hypomethylation results in chromosomal instability, a well-characterized feature of the advanced phases of chronic myeloid leukemia (CML). We investigated methylation changes of DNA repetitive elements (LINE1, Alu, Satellite-alpha and Satellite-2) during the progression of CML from chronic phase (CP) to blast crisis (BC). CP-CML samples were significantly more hypomethylated for all repetitive sequences compared with normal samples. Furthermore, a more profound level of hypomethylation was observed among BC samples compared with CP samples. Our data suggest that repetitive DNA hypomethylation are closely associated with CML progression.

WNT5A, a putative tumour suppressor of lymphoid malignancies, is inactivated by aberrant methylation in acute lymphoblastic leukaemia.

Wnt5a is a member of the Wnt family of proteins that signals through the non-canonical Wnt/Ca(2+) pathway to suppress cyclin D1 expression and negatively regulate B cell proliferation suggesting that it acts as an tumour suppressor for lymphoid leukemogenesis. Although canonical Wnt pathway is a 'hot spot' for methylation in acute lymphoblastic leukaemia (ALL), the role of Wnt5a abnormalities has never been evaluated in this clinical setting. The methylation status of the WNT5A promoter was analysed by methylation-specific PCR (MSP) and sequencing in six ALL-derived cell lines (TOM-1, NALM-20, MY, LOUCY, JURKAT and TANOUE) and in 307 ALL patients. WNT5A and CYCLIN D1 expressions were assessed by quantitative RT-PCR. We observed WNT5A hypermethylation in all cell lines and in cells from 43% (132/307) of ALL patients. WNT5A methylation was associated with decreased WNT5A mRNA expression (P<0.001) and this expression was restored after exposure to the demethylating agent 5-Aza-2'-deoxycytidine. Moreover, WNT5A hypermethylation correlated with upregulation of CYCLIN D1 expression (P=0.002). Disease-free survival (DFS) and overall survival (OS) at 13 and 14 years, respectively, were 59% and 53% for unmethylated patients and 28% and 31% for hypermethylated patients (P=0.0003 and P=0.003). Multivariate analysis demonstrated that WNT5A methylation was an independent prognostic factor predicting DFS (P=0.003) and OS (P=0.04). We have demonstrated that WNT5A, a putative tumour suppressor gene in ALL, is silenced by methylation in this disease and that this epigenetic event is associated with upregulation of CYCLIN D1 expression and confers poor prognosis in this group of patients.

Epigenetic regulation of PRAME gene in chronic myeloid leukemia.

Tumor associated antigens (TAA) provide attractive targets for cancer-specific immunotherapy. PRAME is a TAA gene up-regulated in advanced phases of chronic myeloid leukemia (CML). To date, molecular mechanisms for the expression of PRAME have never been studied. We found that some Ph'-positive cell lines did not express PRAME. The expression of PRAME was restored in these cell lines by treatment with 5'-aza-2'-deoxycytidine, suggesting that the expression of PRAME is mainly suppressed by hypermethylation. Bisulfite sequencing analysis of the CpG sites of the PRAME exon 2 in these cancer cell lines revealed a close relationship between the methylation status of the PRAME gene and its expression. A methylation-specific PCR analysis demonstrated that hypomethylation of PRAME was significantly more frequent in CML blast crisis (70%) than in chronic phase (36%) (P=0.01) and was correlated with high expression levels of PRAME transcripts (P<0.0001). These results suggest that hypomethylation of PRAME up-regulates its expression in CML and might play a significant role in the progression of the disease.

Epigenetic regulation of human cancer/testis antigen gene, HAGE, in chronic myeloid leukemia.

BACKGROUND AND OBJECTIVES: Cancer testis antigens (CTA) provide attractive targets for cancer-specific immunotherapy. Although CTA genes are expressed in some normal tissues, such as the testis, this immunologically protected site lacks MHC I expression and as such, does not present self antigens to T cells. To date, CTA genes have been shown to be expressed in a range of solid tumors via demethylation of their promoter CpG islands, but rarely in chronic myeloid leukemia (CML) or other hematologic malignancies. DESIGN AND METHODS: In this study, the methylation status of the HAGE CTA gene promoter was analyzed by quantitative methylation-specific polymerase chain reaction (MSP) and sequencing in four Philadelphia-positive cell lines (TCC-S, K562, KU812 and KYO-1) and in CML samples taken from patients in chronic phase (CP n=215) or blast crisis (BC n=47). HAGE expression was assessed by quantitative reverse transcriptase-polymerase chain reaction. RESULTS: The TCC-S cell line showed demethylation of HAGE that was associated with over-expression of this gene. HAGE hypomethylation was significantly more frequent in BC (46%) than in CP (22%) (p=0.01) and was correlated with high expression levels of HAGE transcripts (p<0.0001). Of note, in CP-CML, extensive HAGE hypomethylation was associated with poorer prognosis in terms of cytogenetic response to interferon (p=0.01) or imatinib (p=0.01), molecular response to imatinib (p=0.003) and progression-free survival (p=0.05). INTERPRETATIONS AND CONCLUSION: The methylation status of the HAGE promoter directly correlates with its expression in both CML cell lines and patients and is associated with advanced disease and poor outcome.

CpG island methylator phenotype redefines the prognostic effect of t(12;21) in childhood acute lymphoblastic leukemia.

PURPOSE: To examine cancer genes undergoing epigenetic inactivation in a set of ETV6/RUNX1-positive acute lymphoblastic leukemias in order to define the CpG island methylator phenotype (CIMP) in the disease and evaluate its relationship with clinical features and outcome. EXPERIMENTAL DESIGN: Methylation-specific PCR was used to analyze the methylation status of 38 genes involved in cell immortalization and transformation in 54 ETV6/RUNX1-positive samples in comparison with 190 ETV6/RUNX1-negative samples. RESULTS: ETV6/RUNX1-positive samples had at least one gene methylated in 89% of the cases. According to the number of methylated genes observed in each individual sample, 20 patients (37%) were included in the CIMP- group (0-2 methylated genes) and 34 (67%) in the CIMP+ group (>2 methylated genes). Remission rate did not differ significantly among either group of patients. Estimated disease-free survival and overall survival at 9 years were 92% and 100% for the CIMP- group and 33% and 73% for the CIMP+ group (P = 0.002 and P = 0.04, respectively). Multivariate analysis showed that methylation profile was an independent prognostic factor in predicting disease-free survival (P = 0.01) and overall survival (P = 0.05). A group of four genes (DKK3, sFRP2, PTEN, and P73) showed specificity for ETV6/RUNX1-positive subset of samples. CONCLUSION: Our results suggest that methylation profile may be a potential new biomarker of risk prediction in ETV6/RUNX1-positive acute lymphoblastic leukemias.

Promoter hypomethylation of the LINE-1 retrotransposable elements activates sense/antisense transcription and marks the progression of chronic myeloid leukemia.

Aberrant genome-wide hypomethylation is thought to be related to tumorigenesis by promoting genomic instability. Since DNA methylation is considered an important mechanism for the silencing of retroelements, hypomethylation in human tumors may lead to their reactivation. However, the role of DNA hypomethylation in chronic myeloid leukemia (CML) remains to be elucidated. In this study, the methylation status of the LINE-1 (L1) retrotransposon promoter was analysed in CML samples from the chronic-phase (CP, n=140) and the blast crisis (BC, n=47). L1 hypomethylation was significantly more frequent in BC (74.5%) than in CP (38%) (P<0.0001). Furthermore, L1 hypomethylation led to activation of both ORF1 sense transcription (P<0.0001) and c-MET gene antisense transcription (P<0.0001), and was significantly associated with high levels of BCR-ABL (P=0.02) and DNMT3b4 (P=0.001) transcripts. Interestingly, in CP-CML, extensive L1 hypomethylation was associated with poorer prognosis in terms of cytogenetic response to interferon (P=0.004) or imatinib (P=0.034) and progression-free survival (P=0.005). The above results strongly suggest that activation of both sense and antisense transcriptions by aberrant promoter hypomethylation of the L1 elements plays a role in the progression and clinical behavior of the CML.

Promoter hypermethylation of cancer-related genes: a strong independent prognostic factor in acute lymphoblastic leukemia.

Promoter hypermethylation plays an important role in the inactivation of cancer-related genes. This abnormality occurs early in leukemogenesis and seems to be associated with poor prognosis in acute lymphoblastic leukemia (ALL). To determine the extent of hypermethylation in ALL, we analyzed the methylation status of the CDH1, p73, p16, p15, p57, NES-1, DKK-3, CDH13, p14, TMS-1, APAF-1, DAPK, PARKIN, LATS-1, and PTEN genes in 251 consecutive ALL patients. A total of 77.3% of samples had at least 1 gene methylated, whereas 35.9% of cases had 4 or more genes methylated. Clinical features and complete remission rate did not differ among patients without methylated genes, patients with 1 to 3 methylated genes (methylated group A), or patients with more than 3 methylated genes (methylated group B). Estimated disease-free survival (DFS) and overall survival (OS) at 11 years were 75.5% and 66.1%, respectively, for the nonmethylated group; 37.2% and 45.5% for methylated group A; and 9.4% and 7.8% for methylated group B (P < .0001 and P = .0004, respectively). Multivariate analysis demonstrated that the methylation profile was an independent prognostic factor in predicting DFS (P < .0001) and OS (P = .003). Our results suggest that the methylation profile may be a potential new biomarker of risk prediction in ALL.

The suppressor of cytokine signaling-1 is constitutively expressed in chronic myeloid leukemia and correlates with poor cytogenetic response to interferon-alpha.

BACKGROUND AND OBJECTIVES: Interferon-alpha (IFN-alpha) has proven useful for treating chronic myeloid leukemia (CML). However, only 7% of patients achieve a complete cytogenetic response. Although efforts to understand the molecular basis of this resistance to IFN-alpha have been made, the mechanism is still unknown. Because suppressor of cytokine signaling (SOCS) proteins are negative regulators of cytokine-induced signaling, it has been hypothesized that aberrant SOCS expression could confer resistance against cytokine therapy. DESIGN AND METHODS: In order to analyze the role of SOCS-1 in the acquisition of IFN-alpha resistance in this setting, we examined SOCS-1 mRNA expression using reverse transcription polymerase chain reaction (RT-PCR) in 75 newly diagnosed chronic phase-CML patients who received IFN-alpha therapy. RESULTS: SOCS-1 was constitutively expressed in 49 (65%) of 75 CML patients at diagnosis. Constitutive SOCS-1 expression was more frequently observed among Hasford high-risk patients (p = 0.05) and was also independently associated with a shorter median progression-free survival time (p = 0.001) and poor cytogenetic response to IFN-alpha treatment (p 0.0001). INTERPRETATION AND CONCLUSIONS: Our data indicate that constitutive expression of SOCS-1 occurs at an early stage in CML pathogenesis and probably influences the clinical behavior of the disease.

Cadherin-13, a mediator of calcium-dependent cell-cell adhesion, is silenced by methylation in chronic myeloid leukemia and correlates with pretreatment risk profile and cytogenetic response to interferon alfa.

PURPOSE: Cadherin-13 (CDH13) is a newly characterized cadherin molecule responsible for selective cell recognition and adhesion, the expression of which is decreased by methylation in a variety of human cancers, indicating that the CDH13 gene functions as a tumor suppressor gene. Although defective progenitor-stromal adhesion is a well-recognized feature of chronic myeloid leukemia (CML), the role of CDH13 abnormalities has not been evaluated in this disease. PATIENTS AND METHODS: We examined the methylation status of the CDH13 promoter in 179 chronic phase (CP)-CML patients and in 52 advanced-phase samples and correlated it with mRNA expression using methylation-specific polymerase chain reaction (PCR) and reverse transcriptase PCR. RESULTS: Aberrant de novo methylation of the CDH13 promoter region was observed in 99 (55%) of 179 of CP-CML patients, and 90 of the patients failed to express CDH13 mRNA (P <.0001). Advanced-stage samples (n = 52) showed concordant methylation results with their corresponding CP tumors, indicating that CDH13 methylation was not acquired during the course of the disease. Nevertheless, absence of CDH13 expression was more frequently observed among Sokal high-risk patients (P =.01) and was also independently associated with a shorter median progression-free survival time (P =.03) and poor cytogenetic response to interferon alfa treatment (P =.0001). CONCLUSION: Our data indicate that the silencing of CDH13 expression by aberrant promoter methylation occurs at an early stage in CML pathogenesis and probably influences the clinical behavior of the disease.

The role of DNA hypermethylation in the pathogenesis and prognosis of acute lymphoblastic leukemia.

The hallmark of acute lymphoblastic leukemia (ALL) is a progressive appearance of malignant cell behavior that is triggered by the evolution of altered gene function. ALL has traditionally been viewed as a genetic disease, however, epigenetic defects also play an important role. DNA promoter methylation has gained increasing recognition as an important mechanism for transcriptional silencing of cancer related genes. The hypermethylation-associated inactivation affects virtually all of the pathways in the ALL cellular network, such as the cell cycle, apoptosis and adhesion. The identification of these methylation abnormalities and elucidation of the mechanistic events surrounding them are of prime importance, as the methylation status of ALL cells can be used as prognostic biomarker and also can be manipulated in vivo with demethylating agents.