DNA hypermethylation of tumor suppressor genes RASSF6 and RASSF10 as independent prognostic factors in adult acute lymphoblastic leukemia

Targeting DNA Methylation in Leukemia, Myelodysplastic Syndrome, and Lymphoma: A Potential Diagnostic, Prognostic, and Therapeutic Tool

DNA methylation represents a crucial mechanism of epigenetic regulation in hematologic malignancies. The methylation process is controlled by specific DNA methyl transferases and other regulators, which are often affected by genetic alterations. Global hypomethylation and hypermethylation of tumor suppressor genes are associated with hematologic cancer development and progression. Several epi-drugs have been successfully implicated in the treatment of hematologic malignancies, including the hypomethylating agents (HMAs) decitabine and azacytidine. However, combinations with other treatment modalities and the discovery of new molecules are still the subject of research to increase sensitivity to anti-cancer therapies and improve patient outcomes. In this review, we summarized the main functions of DNA methylation regulators and genetic events leading to changes in methylation landscapes. We provide current knowledge about target genes with aberrant methylation levels in leukemias, myelodysplastic syndromes, and malignant lymphomas. Moreover, we provide an overview of the clinical trials, focused mainly on the combined therapy of HMAs with other treatments and its impact on adverse events, treatment efficacy, and survival rates among hematologic cancer patients. In the era of precision medicine, a transition from genes to their regulation opens up the possibility of an epigenetic-based approach as a diagnostic, prognostic, and therapeutic tool.

Transcriptome Profiling of N7-Methylguanosine Modification of Messenger RNA in Drug-Resistant Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is an aggressive hematological tumor caused by the malignant transformation of myeloid progenitor cells. Although intensive chemotherapy leads to an initial therapeutic response, relapse due to drug resistance remains a significant challenge. In recent years, accumulating evidence has suggested that post-transcriptional methylation modifications are strongly associated with tumorigenesis. However, the mRNA profile of m7G modification in AML and its role in drug-resistant AML are unknown. In this study, we used MeRIP-seq technology to establish the first transcriptome-wide m7G methylome profile for AML and drug-resistant AML cells, and differences in m7G between the two groups were analyzed. In addition, bioinformatics analysis was conducted to explore the function of m7G-specific methylated transcripts. We found significant differences in m7G mRNA modification between AML and drug-resistant AML cells. Furthermore, bioinformatics analysis revealed that differential m7G-modified mRNAs were associated with a wide range of cellular functions. Importantly, down-methylated m7G modification was significantly enriched in ABC transporter-related mRNAs, which are widely recognized to play a key role in multidrug resistance. Our results provide new insights into a novel function of m7G methylation in drug resistance progression of AML.

The Tumor Suppressor Role of the Ras Association Domain Family 10

The Ras association domain family 10(RASSF10), a tumor suppressor gene, is located on human chromosome 11p15.2, which is one of the members homologous to other N-terminal RASSF families obtained through structural prediction. RASSF10 plays an important role in inhibiting proliferation, invasion, and migration, inducing apoptosis, making cancer cells sensitive to docetaxel, and capturing G2/M phase. Some studies have found that RASSF10 may inhibit the occurrence and development of tumors by regulating Wnt/β-catenin, P53, and MMP2. Methylation of tumor suppressor gene promoter is a key factor in the development and progression of many tumors. Various methylation detection methods confirmed that the methylation and downregulation of RASSF10 often occur in various tumors, such as gastric cancer, lung cancer, colon cancer, breast cancer, and leukemia. The status of RASSF10 methylation is positively correlated with tumor size, tumor type, and TNM stage. RASSF10 methylation can be used as a prognostic factor for overall survival and disease-free survival, and is also a sign of tumor diagnosis and sensitivity to docetaxel chemotherapy. In this review, we mainly elucidate the acknowledged structure and progress in the verified functions of RASSF10 and the probably relevant signaling pathways.

Methylation as a critical epigenetic process during tumor progressions among Iranian population: an overview

Cancer is one of the main health challenges and leading causes of deaths in the world. Various environmental and genetic risk factors are associated with tumorigenesis. Epigenetic deregulations are also important risk factors during tumor progression which are reversible transcriptional alterations without any genomic changes. Various mechanisms are involved in epigenetic regulations such as DNA methylation, chromatin modifications, and noncoding RNAs. Cancer incidence and mortality have a growing trend during last decades among Iranian population which are significantly related to the late diagnosis. Therefore, it is required to prepare efficient molecular diagnostic panels for the early detection of cancer in this population. Promoter hyper methylation is frequently observed as an inhibitory molecular mechanism in various genes associated with DNA repair, cell cycle regulation, and apoptosis during tumor progression. Since aberrant promoter methylations have critical roles in early stages of neoplastic transformations, in present review we have summarized all of the aberrant methylations which have been reported during tumor progression among Iranian cancer patients. Aberrant promoter methylations are targetable and prepare novel therapeutic options for the personalized medicine in cancer patients. This review paves the way to introduce a non-invasive methylation specific panel of diagnostic markers for the early detection of cancer among Iranians.

Epigenetic Control of Infant B Cell Precursor Acute Lymphoblastic Leukemia

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is a highly aggressive malignancy, with poorer prognosis in infants than in adults. A genetic signature has been associated with this outcome but, remarkably, leukemogenesis is commonly triggered by genetic alterations of embryonic origin that involve the deregulation of chromatin remodelers. This review considers in depth how the alteration of epigenetic profiles (at DNA and histone levels) induces an aberrant phenotype in B lymphocyte progenitors by modulating the oncogenic drivers and tumor suppressors involved in key cancer hallmarks. DNA methylation patterns have been widely studied in BCP-ALL and their correlation with survival has been established. However, the effect of methylation on histone residues can be very different. For instance, methyltransferase KMT2A gene participates in chromosomal rearrangements with several partners, imposing an altered pattern of methylated H3K4 and H3K79 residues, enhancing oncogene promoter activation, and conferring a worse outcome on affected infants. In parallel, acetylation processes provide an additional layer of epigenetic regulation and can alter the chromatin conformation, enabling the binding of regulatory factors. Therefore, an integrated knowledge of all epigenetic disorders is essential to understand the molecular basis of BCP-ALL and to identify novel entry points that can be exploited to improve therapeutic options and disease prognosis.

[Epigallocatechin gallate induces CHD5 gene demethylation to promote acute myeloid leukemia cell apoptosis in vitro by regulating p19Arf-p53-p21Cip1 signaling pathway]

OBJECTIVE

To investigate the mechanism by which epigallocatechin gallate (EGCG) induces CHD5 gene demethylation and promotes the apoptosis of acute myeloid leukemia KG-1 and THP-1 cell lines.

METHODS

KG-1 and THP-1 cells treated with 25, 50, 75, 100 or 150 μg/mL EGCG for 48 h were examined for CHD5 gene methylation using MSP and for cell proliferation using MTT assay. The changes in cell cycle and apoptosis of the two cell lines after treatment with EGCG for 48 h were detected using flow cytometry. The mRNA and protein expressions of DNMT1, CHD5, p19Arf, p53 and p21Cip1 in the cells were detected using RT-quantitative PCR and Western blot.

RESULTS

EGCG dose-dependently reversed hypermethylation of CHD5 gene and reduced the cell viability in both KG-1 and THP-1 cells (P < 0.05). EGCG treatment caused obvious cell cycle arrest in G1 phase, significantly increased cell apoptosis, downregulated the expression of DNMT1 and upregulated the expressions of CHD5, p19Arf, p53 and p21Cip1 in KG-1 and THP-1 cells (P < 0.05).

CONCLUSIONS

EGCG reduces hypermethylation of CHD5 gene in KG-1 and THP-1 cells by downregulating DNMT1 to restore its expression, which results in upregulated expressions of p19Arf, p53 and p21Cip1 and induces cell apoptosis.

Genetics of blood malignancies among Iranian population: an overview

BACKGROUND

Blood malignancies are among the leading causes of cancer related deaths in the world. Different environmental and genetic risk factors are involved in progression of blood malignancies. It has been shown that the lifestyle changes have affected the epidemiological patterns of these malignancies. Hematologic cancers are the 5th common cancer among Iranian population. It has been observed that there is a rising trend of blood malignancies incidences during the recent decades. Therefore, it is required to design novel diagnostic methods for the early detection of such malignancies in this population.

MAIN BODY

In present review we have summarized all of the significant genes which have been reported among Iranian patients with blood malignancies. The reported genes were categorized based on their cell and molecular functions to clarify the molecular biology and genetics of blood malignancies among Iranian patients.

CONCLUSION

It was observed that the epigenetic and immune response factors were the most frequent molecular processes associated with progression of blood malignancies among Iranian population. This review paves the way of introducing a population based panel of genetic markers for the early detection of blood malignancies in this population.

Integration of intratumoral RASSF10 expression and tumor-associated macrophages into the established clinical indicators better predicts the prognosis of clear cell renal cell carcinoma patients

A helpful evaluation system is crucial for the postoperative prognosis prediction of clear cell renal cell carcinoma (ccRCC) patients. This study determined the prognostic value of combining intratumoral RASSF10 expression and tumor-associated macrophages (TAMs) with the established clinicopathological indicators in ccRCC patients. RASSF10 expression was analyzed in ccRCC patient data from online databases and ccRCC cell lines. Two independent ccRCC patient cohorts were employed to examine the prognostic value of RASSF10 and other markers by immunohistochemistry (IHC) and statistical analyses. We found that RASSF10 expression was downregulated in ccRCC specimens from the TCGA datasets and three independent institutions. RASSF10 expression was negatively correlated with disease progression and TAM infiltration in ccRCC. In addition, low RASSF10 expression and high TAM infiltration predicted a high TNM stage, SSIGN score, WHO/ISUP grading, and a poor prognosis in two independent ccRCC patient cohorts. Moreover, RASSF10, CD68 or CD163, TNM stage, and SSIGN score were identified as independent risk factors in predicting ccRCC patients' prognosis. Time-dependent c-index analyses revealed that the combination of RASSF10 and TAMs resulted in a higher index than that resulting from each alone in the postoperative prognosis of ccRCC patients, and the integration of RASSF10 and TAMs with the TNM stage or SSIGN score achieved the best accuracy in assessing the prognosis of ccRCC patients. These findings were validated in the randomized training, validation, and combined cohorts. Taken together, the combination of the RASSF10-TAM classifier and current clinical parameters yields superior accuracy in predicting the ccRCC patients' postoperative outcome.

Predictive value of the serum RASSF10 promoter methylation status in gastric cancer

Background

This study aimed to investigate whether the detection of methylation in the promoter of the Ras association domain family 10 gene (RASSF10) in the serum of patients with gastric cancer (GC) by methylation-specific PCR (MSP) can be used as a diagnostic and prognostic indicator of GC.

Methods

We used MSP to examine RASSF10 methylation levels in the serum and/or tumor samples from 100 GC patients, 50 patients with chronic atrophic gastritis (CAG), and 45 healthy controls (HC). We also analyzed clinicopathological and follow-up data.

Results

Our results showed that the rate of serum RASFF10 promoter methylation among patients with GC (49/100) was higher than in those with CAG (1/50) or HC (0/45). Moreover, the RASSF10 methylation status was consistent between serum and tumor tissues. GC patients with serum RASSF10 promoter methylation had significantly shorter overall survival and disease-free survival times than GC patients without serum RASSF10 promoter methylation. Multivariable Cox regression analysis showed that serum RASSF10 promoter methylation and lymph node metastasis both correlated with reduced survival in GC patients.

Conclusions

Detection of the serum RASSF10 methylation status by MSP is feasible as a diagnostic and prognostic indicator of GC.