Overexpression of DNA methyltransferase 1 as a negative independent prognostic factor in primary gastrointestinal diffuse large B-cell lymphoma treated with CHOP-like regimen and rituximab

Palmitic acid reduces the methylation of the FOXO1 promoter to suppress the development of diffuse large B-cell lymphoma via modulating the miR-429/DNMT3A axis

Diffuse large B-cell lymphoma (DLBCL) is characterized by significant treatment resistance. Palmitic acid (PA) has shown promising antitumor properties. This study aims to elucidate the molecular mechanisms by which PA influences DLBCL progression. We quantified the expression levels of microRNAs (miRNAs), Forkhead box protein O1 (FOXO1), and DNA methyltransferase 3A (DNMT3A) in both untreated and PA-treated DLBCL tumors and cell lines. Assessments were made of cell viability, apoptosis, and autophagy-related protein expression following PA administration. Interaction analyses among miR-429, DNMT3A, and FOXO1 were conducted using luciferase reporter assays and methylation-specific (MSP) Polymerase chain reaction (PCR). After transfecting the miR-429 inhibitor, negative control (NC) inhibitor, shRNA against DNMT3A (sh-DNMT3A), shRNA negative control (sh-NC), overexpression vector for DNMT3A (oe-DNMT3A), or overexpression negative control (oe-NC), we evaluated the effects of miR-429 and DNMT3A on cell viability, mortality, and autophagy-related protein expression in PA-treated DLBCL cell lines. The efficacy of PA was also tested in vivo using DLBCL tumor-bearing mouse models. MiR-429 and FOXO1 expression levels were downregulated, whereas DNMT3A was upregulated in DLBCL compared to the control group. PA treatment was associated with enhanced autophagy, mediated by the upregulation of miR-429 and downregulation of DNMT3A. The luciferase reporter assay and MSP confirmed that miR-429 directly inhibits DNMT3A, thereby reducing FOXO1 methylation. Subsequent experiments demonstrated that PA promotes autophagy and inhibits DLBCL progression by upregulating miR-429 and modulating the DNMT3A/FOXO1 axis. In vivo PA significantly reduced the growth of xenografted tumors through its regulatory impact on the miR-429/DNMT3A/FOXO1 axis. Palmitic acid may modulate autophagy and inhibit DLBCL progression by targeting the miR-429/DNMT3A/FOXO1 signaling pathway, suggesting a novel therapeutic target for DLBCL management.

Advances in diagnosis, treatment and prognostic factors of gastrointestinal DLBCL

Gastrointestinal diffuse large B-cell lymphoma (GI-DLBCL) is an extremely aggressive form of B-cell non-Hodgkin lymphoma (BNHL) which has complex histological characteristics and manifests a high degree of heterogeneity in terms of clinical, morphological, immunological, and genetic features. GI-DLBCL mainly spreads by infiltrating neighboring lymph nodes, and common gastrointestinal complications (GICS) such as obstruction, perforation, or bleeding, frequently arise during the progression of the disease, posing significant challenges in both diagnosing and treating the condition. Meanwhile, the incidence of GI-DLBCL has been gradually increasing in recent years, and its strong invasiveness makes it prone to being misdiagnosed or completely missed. In clinical practice, over half of the patients diagnosed with the disease are in stage III or stage IV. What makes it worse is that certain patients may not exhibit a favorable response to chemotherapy. All these lead to intricacies in management of this disease. Unfortunately, there is currently no large prospective study or evidence-based medical evidence to provide clear guidance on treatment decisions for this specific type of lymphoma. Neither do physicians have a consensus regarding the optimal approach to address this condition. Recent studies have identified the presence of various prognostic factors that significantly impact survival in GI-DLBCL, which demonstrates the unique particularity of GI-DLBCL, and could help optimize the clinical decision.

Epigenetic regulation in hematopoiesis and its implications in the targeted therapy of hematologic malignancies

Hematologic malignancies are one of the most common cancers, and the incidence has been rising in recent decades. The clinical and molecular features of hematologic malignancies are highly heterogenous, and some hematologic malignancies are incurable, challenging the treatment, and prognosis of the patients. However, hematopoiesis and oncogenesis of hematologic malignancies are profoundly affected by epigenetic regulation. Studies have found that methylation-related mutations, abnormal methylation profiles of DNA, and abnormal histone deacetylase expression are recurrent in leukemia and lymphoma. Furthermore, the hypomethylating agents and histone deacetylase inhibitors are effective to treat acute myeloid leukemia and T-cell lymphomas, indicating that epigenetic regulation is indispensable to hematologic oncogenesis. Epigenetic regulation mainly includes DNA modifications, histone modifications, and noncoding RNA-mediated targeting, and regulates various DNA-based processes. This review presents the role of writers, readers, and erasers of DNA methylation and histone methylation, and acetylation in hematologic malignancies. In addition, this review provides the influence of microRNAs and long noncoding RNAs on hematologic malignancies. Furthermore, the implication of epigenetic regulation in targeted treatment is discussed. This review comprehensively presents the change and function of each epigenetic regulator in normal and oncogenic hematopoiesis and provides innovative epigenetic-targeted treatment in clinical practice.

High DNMT1 Expression in Stromal Fibroblasts Promotes Angiogenesis and Unfavorable Outcome in Locally Advanced Breast Cancer Patients

Background

Active breast cancer-associated fibroblasts (CAFs) play a leading role in breast carcinogenesis through promoting angiogenesis and resistance to therapy. Consequently, these active stromal cells have significant influence on patient outcome. Therefore, we explored here the role of the DNA methyltransferase 1 (DNMT1) protein in CAF-dependent promotion of angiogenesis as well as the prognostic power of DNMT1 level in both cancer cells and their adjacent CAFs in locally advanced breast cancer patients.

Methods

We applied immunohistochemistry to evaluate the level of DNMT1 in breast cancer tissues and their adjacent normal counterparts. Quantitative RT-PCR and immunoblotting were performed to investigate the role of DNMT1 in regulating the expression of pro-angiogenic genes in active CAFs and also their response to the DNMT1 inhibitors decitabine (DAC) as well as eugenol.

Results

We have shown that DNMT1 controls the pro-angiogenic potential of CAFs both in vitro and in vivo through positive regulation of the expression/secretion of 2 important pro-angiogenic factors VEGF-A and IL-8 as well as their upstream effectors mTOR and HIF-1α. To confirm this, we have shown that these DNMT1-related pro-angiogenic effects were suppressed by 2 DNMT1 inhibitors decitabine and eugenol. Interestingly, in a cohort of 100 tumors from locally advanced breast cancer patients (LABC), we have shown that high expression of DNMT1 in tumor cells and their adjacent stromal fibroblasts is correlated with poor survival of these patients.

Conclusion

DNMT1 upregulation in breast stromal fibroblasts promotes angiogenesis via IL-8/VEGF-A upregulation, and correlates well with poor survival of LABC patients.

Migration and Adhesion of B-Lymphocytes to Specific Microenvironments in Mantle Cell Lymphoma: Interplay between Signaling Pathways and the Epigenetic Landscape

Lymphocyte migration to and sequestration in specific microenvironments plays a crucial role in their differentiation and survival. Lymphocyte trafficking and homing are tightly regulated by signaling pathways and is mediated by cytokines, chemokines, cytokine/chemokine receptors and adhesion molecules. The production of cytokines and chemokines is largely controlled by transcription factors in the context of a specific epigenetic landscape. These regulatory factors are strongly interconnected, and they influence the gene expression pattern in lymphocytes, promoting processes such as cell survival. The epigenetic status of the genome plays a key role in regulating gene expression during many key biological processes, and it is becoming more evident that dysregulation of epigenetic mechanisms contributes to cancer initiation, progression and drug resistance. Here, we review the signaling pathways that regulate lymphoma cell migration and adhesion with a focus on Mantle cell lymphoma and highlight the fundamental role of epigenetic mechanisms in integrating signals at the level of gene expression throughout the genome.

Epigenetic silencing of miR-342-3p in B cell lymphoma and its impact on autophagy

Background

miR-342-3p, localized to 14q32, is a tumor suppressor miRNA implicated in carcinogenesis. Given the presence of a promotor-associated CpG island for its host gene, EVL, we hypothesized that intronic miR-342-3p is a tumor suppressor co-regulated with host gene by promoter DNA methylation in B cell lymphoma.

Results

By bisulfite pyrosequencing-verified methylation-specific PCR (MSP), EVL/MIR342 methylation was detected in five (50%) lymphoma cell lines but not normal peripheral blood and tonsils. EVL/MIR342 methylation correlated with repression of both miR-342-3p and EVL in cell lines. In completely methylated SU-DHL-16 cells, 5-AzadC treatment resulted in promoter demethylation and re-expression of miR-342-3p and EVL. In 132 primary lymphoma samples, EVL/MIR342 was preferentially methylated in B cell lymphomas (N = 68; 68.7%) than T cell lymphoma (N = 8; 24.2%) by MSP (P < 0.0001). Moreover, EVL/MIR342 methylation was associated with lower miR-342-3p expression in 79 primary NHL (P = 0.0443). In SU-DHL-16 cells, the tumor suppressor function of miR-342-3p was demonstrated by the inhibition of cellular proliferation and increase of cell death upon over-expression of miR-342-3p. Mechanistically, overexpression of miR-342-3p resulted in a decrease of LC3-II, a biomarker of autophagy, which was pro-survival for SU-DHL-16. Pre-treatment with 3-methyladenine, an autophagy inhibitor, abrogated tumor suppression associated with miR-342-3p overexpression. By luciferase assay, MAP1LC3B, a precursor of LC3-II, was confirmed as a direct target of miR-342-3p. Finally, in SU-DHL-16 cells, overexpression of miR-342-3p downregulated the known target DNMT1, with promoter demethylation and re-expression of tumor suppressor E-cadherin.

Conclusions

Intronic miR-342-3p is co-regulated with its host gene EVL by tumor-specific promoter DNA methylation in B cell lymphoma. The tumor suppressor function of miR-342-3p was mediated via inhibition of pro-survival autophagy by targeting MAP1LC3B and downregulation of DNMT1 with demethylation and re-expression of tumor suppressor genes.

Overexpression of microRNA-130a predicts adverse prognosis of primary gastrointestinal diffuse large B-cell lymphoma

Primary gastrointestinal diffuse large B-cell lymphoma (PGI-DLBCL) is a highly heterogeneous type of non-Hodgkin lymphoma. A number of studies have demonstrated that microRNA-130a (miR-130a) serves a role in the tumorigenesis and prognosis of numerous human tumors. However, to the best of our knowledge, the prognostic significance of miR-130a in PGI-DLBCL remains unknown. The present study explored the association between miR-130a and the clinical outcomes of PGI-DLBCL. Relative miR-130a expression was assessed by reverse transcription-quantitative PCR. Immunohistochemistry was used to detect expression levels of BCL-2, c-MYC, neprilysin, B-cell lymphoma 6 protein, PWWP domain-containing DNA repair factor 3A and proliferation marker protein Ki-67. A receiver operating characteristic curve was constructed to analyze the specificity and sensitivity of microRNA levels in the diagnosis of PGI-DLBCL. Survival curves were constructed using the Kaplan-Meier method. In the present study, miR-130a expression was notably higher in patients with PGI-DLBCL compared with in the controls (P<0.0001). miR-130a overexpression was closely associated with a high International Prognostic Index score (3–5) and drug resistance (P=0.017 and P=0.044, respectively). No significant difference in other clinical features was observed. Patients with increased expression levels of miR-130a had lower overall survival [hazard ratio (HR), 2.998; 95% CI, 1.347-6.673; P=0.007] and progression-free survival (HR, 3.325; 95% CI, 1.488-7.429; P=0.003) compared with patients who had lower expression levels of miR-130a. Furthermore, multivariate Cox regression analysis suggested that miR-130a was a negative prognostic parameter in PGI-DLBCL. Therefore, upregulation of miR-130a could become a potential prognostic marker for PGI-DLBCL. Additionally, further study of these results may have important guiding significance for the prognosis of patients with PGI-DLBCL in the clinical setting.

Using Informatics Tools to Identify Opportunities for Precision Medicine in Diffuse Large B-cell Lymphoma

INTRODUCTION

Diffuse large B-cell lymphoma (DLBCL) is genetically and clinically heterogeneous. Despite advances in genomic subtyping, standard frontline chemoimmunotherapy has remained unchanged for years. As high-throughput analysis becomes more accessible, characterizing drug-gene interactions in DLBCL could support patient-specific treatment strategies.

MATERIALS AND METHODS

From our systematic literature review, we compiled a comprehensive list of somatic mutations implicated in DLBCL. We extracted reported and primary sequencing data for these mutations and assessed their association with signaling pathways, cell-of-origin subtypes, and clinical outcomes.

RESULTS

Twenty-two targetable mutations present in ≥ 5% of patients with DLBCL were associated with unfavorable outcomes, yielding a predicted population of 31.7% of DLBCL cases with poor-risk disease and candidacy for targeted therapy. A second review identified 256 studies that had characterized the drug-gene interactions for these mutations via in vitro studies, mouse models, and/or clinical trials.

CONCLUSIONS

Our novel approach linking the data from our systematic reviews with informatics tools identified high-risk DLBCL subgroups, DLBCL-specific drug-gene interactions, and potential populations for precision medicine trials.

Downregulation of syndecan‑1 expression induces activation of hepatic stellate cells via the TGF‑β1/Smad3 signaling pathway

The activation of hepatic stellate cells (HSCs) is considered associated with liver fibrosis. However, the exact role of syndecan‑1 (SDC1), a protein that regulates the interaction between cells and the microenvironment, in the activation of HSCs resulting in liver fibrosis remains elusive. The objective of the present study was to explore the effects and mechanism of action of SDC1 in the activation of HSCs. HSCs were isolated from mouse liver and cultured to detect the expression of SDC1, transforming growth factor (TGF)‑β1, Smad3 and α‑smooth muscle actin (α‑SMA; a marker of HSC activation) by western blotting and reverse transcription‑quantitative PCR. The expression of SDC1 was found to be downregulated, while the expression of TGF‑β1, Smad3 and α‑SMA was upregulated in HSCs during cell culture. In addition, following stimulation of HSCs with recombinant SDC1, the expression of TGF‑β1, Smad3 and α‑SMA in HSCs was downregulated, whereas small interfering RNA targeting Smad3 antagonized the effects of recombinant SDC1 on α‑SMA. Taken together, these data suggest that SDC1 plays a key role in the development of liver fibrosis.

Tissue-specific induced DNA methyltransferase 1 (Dnmt1) in endocrine pancreas by RCAS-TVA-based somatic gene transfer system promotes β-cell proliferation

We reported that inactivation of menin (the protein product of MEN1) increases activity of Dnmt1 and mediates DNA hypermethylation in the development of multiple endocrine neoplasia type 1 (MEN1) syndrome. We have developed a RCAS-TVA-based somatic gene transfer system that enables tissue-specific delivery of Dnmt1 to individual β-cells of the pancreas in a RIP-TVA mouse model. In the present study, we mediated Dnmt1 expression in islet β-cells in RIP-TVA mice by utilizing the RCAS-TVA system to test if the upregulation of Dnmt1 can promote β-cell proliferation. In vitro, we demonstrated that upregulation of Dnmt1 increased β-cell proliferation. In vivo, our results showed that the levels of serum insulin were increased in the RIP-TVA mice with RCASBP-Dnmt1 infection compared with wild-type control mice with RCASBP-Dnmt1 infection. Furthermore, we confirmed that mRNA and protein expression of Dnmt1 as well as Dnmt1 enzyme activity were upregulated in the RIP-TVA mice with RCASBP-Dnmt1 infection compared with wild-type control mice with RCASBP-Dnmt1 infection. Finally, we demonstrated that upregulation of Dnmt1 resulted in hyperplasia through β-cell proliferation. We conclude that the upregulation of Dnmt1 promotes islet β-cell proliferation and targeting Dnmt1 may be a promising therapy for patients suffering from pancreatic neuroendocrine tumors.

An epigenetic regulator-related score (EpiScore) predicts survival in patients with diffuse large B cell lymphoma and identifies patients who may benefit from epigenetic therapy

Diffuse large B-cell lymphoma (DLBCL) is the most common form of lymphoma and shows considerable clinical and biological heterogeneity. Much research is currently focused on the identification of prognostic markers for more specific patients’ risk stratification and on the development of therapeutic approaches to improve the long-term outcome. Epigenetic alterations are involved in various cancers, including lymphoma. Interestingly, epigenetic alterations are reversible and drugs to target some of them have been developed. In this study, we demonstrated that the gene expression profile of epigenetic regulators has a prognostic value in DLBCL and identified pathways that could be involved in DLBCL poor outcome. We then designed a new risk score (EpiScore) based on the gene expression level of the epigenetic regulators DNMT3A, DOT1L, SETD8. EpiScore was predictive of overall survival in DLBCL and allowed splitting patients with DLBCL from two independent cohorts (n = 414 and n = 69) in three groups (high, intermediate and low risk). EpiScore was an independent predictor of survival when compared with previously described prognostic factors, such as the International Prognostic Index (IPI), germinal center B cell and activated B cell molecular subgroups, gene expression-based risk score (GERS) and DNA repair score. Immunohistochemistry analysis of DNMT3A in 31 DLBCL samples showed that DNMT3A overexpression (>42% of positive tumor cells) correlated with reduced overall and event-free survival. Finally, an HDAC gene signature was significantly enriched in the DLBCL samples included in the EpiScore high-risk group. We conclude that EpiScore identifies high-risk patients with DLBCL who could benefit from epigenetic therapy.

Nine primary malignant neoplasms-involving the esophagus, stomach, colon, rectum, prostate, and external ear canal-without microsatellite instability: a case report

BACKGROUND

Although cases of multiple primary malignant neoplasms are increasing, reports of more than three or four primary metachronous malignant neoplasms are extremely rare. Moreover, very few publications have provided a genetic mutational analysis or have evaluated risk factors associated with such neoplasms. We present an extremely rare case of nine primary malignant lesions in a man who was successfully treated. We also report on microsatellite stability status, analyze risk factors, and discuss the relevant literature.

CASE PRESENTATION

Between 67 and 73 years of age, a male patient developed nine primary metachronous malignant lesions: Three were located in the esophagus, two in the stomach, two in the colorectum, one in the prostate gland, and one in the external ear canal. The patient's clinical history included hypertension, atrial fibrillation, an acoustic schwannoma, and heavy smoking. The lesions were diagnosed during regular screening over a six-year period. He was successfully treated with surgery (both open surgical and endoscopic resection of lesions) and adjuvant chemotherapy. Immunohistochemistry and mutational analysis showed that the lesions were microsatellite stable, and the KRAS, BRAF, p53, and nuclear β-catenin status was not uniform among the lesions.

CONCLUSIONS

Given that the presence of more than three or four neoplasms is extremely rare, the present case of nine primary malignancies with no associated microsatellite instability and no apparent predisposing hereditary conditions, is extraordinary. Our case study shows that it is possible for up to nine sporadic neoplasms to occur, and efficient disease management requires diligent screening and early detection.

A higher degree of expression of DNA methyl transferase 1 in cervical cancer is associated with poor survival outcome

Background

Even though novel therapies based on aberrant DNA methylation could be of particular importance for the treatment of cervical cancer (CC) because the oncoproteins E6/E7 of high-risk human papillomaviruses, the causative agents for developing CC, have the capacity to bind and upregulate DNA methyltransferases (DNMTs), to our knowledge, no previous studies have evaluated the expression of this enzyme in CC in relation to survival outcomes. The purpose of the study was to evaluate the expression of DNMT1 in CC and its association with survival outcomes.

Methods

The study population consisted of 76 women treated for primary CC and followed up by the University of Alabama at Birmingham (UAB) cancer registry. The expression of DNMT1 was examined using immunohistochemistry, and the degree of expression of DNMT1 was expressed as a percentage of cells positive for DNMT1 and its intensity. Cox proportional hazards model was used to assess the relationship between the degree of expression of DNMT1 and overall survival after adjusting for relevant covariates.

Results

The expression of DNMT1 was significantly higher in CC cells compared to that in the normal cervical epithelium. A higher percentage of cells positive for DNMT1 and a higher intensity score for DNMT1 were significantly associated with poor survival outcome (hazard ratio [HR] =4.3, P=0.03 and HR =4.9, P=0.02, respectively).

Conclusion

Our findings suggested that the degree of expression of DNMT1 could be considered as a target in the epigenetic treatment of CC. Replication of our results in other study populations with CC could create the opportunity of using DNMT inhibitors to treat CC.

The Lymphocyte-Monocyte Ratio and the Platelet-Lymphocyte Ratio at Diagnosis as Independent Prognostic Factors in Primary Gastrointestinal Diffuse Large B Cell Lymphoma

To study the role of the absolute lymphocyte count (ALC), absolute monocyte count (AMC), platelet count (PLT), lymphocyte-monocyte ratio (LMR) and the platelet-lymphocyte ratio (PLR) in the prognosis of primary gastrointestinal diffuse large B cell lymphoma (PGI-DLBCL). We retrospectively analyzed the prognostic value of the ALC, AMC, PLT, LMR, PLR at diagnosis in 173 PGI-DLBCL patients through histopathological examination from March 2009 to February 2015. In total, 173 patients with histopathological diagnosis of PGI-DLBCL in this study, the median age was 51 years (range 12-90 years), median follow-up time was 44 months (range 7-89 months). In univariate analysis, age <60 years, B symptoms, Lugano stage I-II, low international prognostic index (IPI) or low age-adjusted international prognostic index (aaIPI), normal lactate dehydrogenase (LDH), normal β2-microglobulin (β2m), Hb ≥ 11 g/dL, ALC ≥ 1.5 × 10⁹/L, AMC ≤ 0.50 × 10⁹/L, LMR ≥ 2.5, PLR ≤ 170 were related with superior overall survival (OS) and progression-free survival (PFS) (p ≤ 0.05). Multivariate analysis suggested that ALC, LMR, LDH were related with PFS (p ≤ 0.05). Similarly, age and LMR were related with OS (p ≤ 0.05). The parameters (ALC, AMC, LMR, PLR) may be valuable prognostic factors in PGI-DLBCL patients. LMR, PLR at diagnosis are expected to be independent prognostic factors for PGI-DLBCL patients.

Inhibition of EZH2 via activation of SAPK/JNK and reduction of p65 and DNMT1 as a novel mechanism in inhibition of human lung cancer cells by polyphyllin I

Background

Polyphyllin I (PPI), a bioactive phytochemical extracted from the Rhizoma of Paris polyphylla, has been reported to exhibit anti-cancer activity. However, the detailed mechanism underlying this remains to be elucidated.

Methods

Cell viability and cell cycle distribution were measured using a 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and flow cytometry assays, respectively. The expression of enhancer of zeste homolog 2 (EZH2) mRNA was measured by quantitative real time PCR (qRT-PCR). Western blot analysis was performed to examine the phosphorylation and protein expression of stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), p65, DNA methyltransferase 1 (DNMT1) and EZH2. Exogenous expression of p65, DNMT1, and EZH2 were carried out by transient transfection assays. Promoter activity of EZH2 gene was determined using Secrete-Pair Dual Luminescence Assay Kit. A xenografted tumor model in nude mice and bioluminescent imaging system were used to further test the effect of PPI in vivo.

Results

We showed that PPI significantly inhibited growth and induced cell cycle arrest of non-small cell lung cancer (NSCLC) cells in a dose-dependent manner. Mechanistically, we found that PPI increased the phosphorylation of SAPK/JNK, reduced protein expression of p65 and DNMT1. The inhibitor of SAPK/JNK (SP600125) blocked the PPI-inhibited p65 and DNMT1 protein expression. Interestingly, exogenously expressed p65 overcame PPI-inhibited protein expression of DNMT1. Moreover, PPI reduced EZH2 protein, mRNA, and promoter activity; overexpression of EZH2 resisted the PPI-inhibited cell growth, and intriguingly, negative feedback regulation of SAPK/JNK signaling. Finally, exogenous expression of DNMT1 antagonized the PPI-suppressed EZH2 protein expression. Consistent with this, PPI inhibited tumor growth, protein expression levels of p65, DNMT1 and EZH2, and increased phosphorylation of SAPK/JNK in vivo.

Conclusion

Our results show that PPI inhibits growth of NSCLC cells through SAPK/JNK-mediated inhibition of p65 and DNMT1 protein levels, subsequently; this results in the reduction of EZH2 gene expression. The interactions among p65, DNMT1 and EZH2, and feedback regulation of SAPK/JNK by EZH2 converge on the overall responses of PPI. This study reveals a novel mechanism for regulating EZH2 gene in response to PPI and suggests a new strategy for NSCLC associated therapy.

Differential expression of the epigenetic methylation-related protein DNMT1 by breast cancer molecular subtype and stromal histology

Background

We assessed the expression of methylation-related proteins 5-meC, DNMT1, and ISL-1 in breast cancer and evaluated their relationship to clinicopathological factors.

Methods

Immunohistochemical staining for ER, PR, HER-2, Ki-67, 5-meC, DNMT1, and ISL-1 were performed on 348 breast cancer samples in tissue microarray. Samples were subgrouped into luminal A, luminal B, HER-2, or triple-negative breast cancer (TNBC) according to immunohistochemical staining for ER, PR, HER-2, and Ki-67. The tumor stroma was histologically subtyped into desmoplastic, sclerotic, normal-like, or inflammatory type.

Results

Tumor expression of DNMT1 differed by molecular subtype: it was higher in TNBC and lower in luminal A (p < 0.001) samples. DNMT1 expression was also related to higher histologic grade, ER negativity, PR negativity, and higher Ki-67 LI (p < 0.001). In western blot, protein expressions of DNMT1 and ISL-1 were higher in TNBC and relatively lower in the remaining subtypes. High tumor expression of DNMT1 was associated with shorter OS in univariate analysis (p = 0.041). DNMT1 and 5-meC were differentially expressed by stromal phenotype: 5-meC was higher in normal-like type and lower in sclerotic type (p = 0.049); DNMT1 was higher in inflammatory and lower in sclerotic type (p < 0.001).

Conclusions

Tumor expression of DNMT1 in breast cancer differed by molecular subtype and stromal histological type. DNMT1 was highly expressed in TNBC and in breast cancer with inflammatory stromal type.