5-Azacitidine induces demethylation of PTPL1 and inhibits growth in non-Hodgkin lymphoma

5‑Aza‑dC suppresses melanoma progression by inhibiting GAS5 hypermethylation

The in‑depth study of melanoma pathogenesis has revealed that epigenetic modifications, particularly DNA methylation, is a universal inherent feature of the development and progression of melanoma. In the present study, the analysis of the tumor suppressor gene growth arrest‑specific transcript 5 (GAS5) demonstrated that its expression was downregulated in melanoma, and its expression level had a certain negative association with its methylation modification level. The promoter of GAS5 presented with detectable CpG islands, and methylation‑specific polymerase chain reaction analysis demonstrated that GAS5 was actually modified by methylation in melanoma tissues and cells; however, no methylation modification of GAS5 was detected in normal tissues. Following the treatment of melanoma cells with 5‑Aza‑2'‑deoxycytidine (5‑Aza‑dC), GAS5 methylation was significantly reversed. The analysis of melanoma cell proliferation revealed that 5‑Aza‑dC inhibited A375 and SK‑MEL‑110 cell proliferation in a time‑dependent manner. Further analysis of apoptosis demonstrated that 5‑Aza‑dC significantly increased the apoptosis level of the two cell lines. Moreover, migration analysis of melanoma cells revealed that 5‑Aza‑dC significantly reduced cell migration. Furthermore, 5‑Aza‑dC significantly decreased the invasive ability of the two cell lines. However, when the expression of GAS5 was silenced, the effects of 5‑Aza‑dC on cell proliferation, apoptosis, invasion and migration were not significant. Furthermore, the subcutaneous injection of A375 cells in nude mice successfully resulted in xenograft tumor formation. However, following an intraperitoneal injection of 5‑Aza‑dC, the volume and weight of xenograft tumors and Ki‑67 expression were significantly reduced, and caspase‑3 activity and GAS5 expression were enhanced; following the silencing of GAS5, the antitumor effect of 5‑Aza‑dC was significantly blocked. On the whole, the present study demonstrates that 5‑Aza‑dC inhibits the growth of melanoma, and its function may be related to the methylation modification of GAS5.

Low-Dose 5-Aza and DZnep Alleviate Acute Graft-Versus-Host Disease With Less Side Effects Through Altering T-Cell Differentiation

Objective

Previous studies showed that hypomethylating agents (HMAs) could alleviate acute graft-versus-host disease (aGvHD), but affect engraftment after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The combination of two different HMAs in lower doses might overcome this problem. This study aimed to evaluate the treatment effect of the combination of two HMAs—azacitidine (5-Aza) and histone H3K27 methyltransferase inhibitor 3-deazaneplanocin (DZNep)—for the prophylaxis of aGvHD after allo-HSCT and to explore the possible mechanisms.

Methods

We first optimized the concentrations of individual and combinational 5-Aza and DZNep treatments to ensure no obvious toxicities on activated T cells by evaluating T-cell proliferation, viability, and differentiation. A mouse model of aGvHD was then established to assess the prophylactic efficacy of 5-Aza, DZNep, and their combination on aGvHD. The immunomodulatory effect on T cells and the hematopoietic reconstruction were assessed. Additionally, RNA sequencing (RNA-seq) was performed to identify the underlying molecular mechanisms.

Results

Compared with single treatments, the in vitro application of 5-Aza with DZNep could more powerfully reduce the production of T helper type 1 (Th1)/T cytotoxic type 1 (Tc1) cells and increase the production of regulatory T cells (Tregs). In an allo-HSCT mouse model, in vivo administration of 5-Aza with DZNep could enhance the prophylactic effect for aGvHD compared with single agents. The mechanism study demonstrated that the combination of 5-Aza and DZNep in vivo had an enhanced effect to inhibit the production of Th1/Tc1, increase the proportions of Th2/Tc2, and induce the differentiation of Tregs as in vitro. RNA-seq analysis revealed the cytokine and chemokine pathways as one mechanism for the alleviation of aGvHD with the combination of 5-Aza and DZNep.

Conclusion

The combination of 5-Aza and DZNep could enhance the prophylactic effect for aGvHD by influencing donor T-cell differentiation through affecting cytokine and chemokine pathways. This study shed light on the effectively prophylactic measure for aGvHD using different epigenetic agent combinations.

ARID1A genomic alterations driving microsatellite instability through somatic MLH1 methylation with response to immunotherapy in metastatic lung adenocarcinoma: a case report

BACKGROUND

Tumor molecular screening allows categorization of molecular alterations to select the best therapeutic strategy. AT-rich interactive domain-containing 1A (ARID1A) gene mutations are present in gastric, endometrial, and clear cell ovarian tumors. Inactivation of this gene impairs mismatch repair (MMR) machinery leading to an increased mutation burden that correlates with microsatellite instability (MSI), associated with tumor-infiltrating lymphocytes and programmed death ligand 1 (PD-L1) expression. This is the first case report in lung adenocarcinoma of ARID1A gene alterations leading to sporadic MSI, through somatic mutL homolog 1 (MLH1) promoter methylation, with an MLH1 gene mutation as the second somatic hit.

CASE PRESENTATION

A 50-year-old never-smoker Bulgarian woman, with no comorbidities and no family history of cancer, was diagnosed with metastatic lung adenocarcinoma. PD-L1 immunohistochemistry (IHC) of tissue biopsies on right groin adenopathies resulted in 30% positivity. Liquid biopsy test reported actionable alterations in ARID1A gene, rearranged during transfection (RET) gene fusions, epidermal growth factor receptor (EGFR) gene R776H mutation, breast cancer (BRCA) genes 1/2, and cyclin-dependent kinase inhibitor 2A (CDKN2A) gene mutations. The patient was treated with immunotherapy, and showed a treatment response lasting for 19 months until a new metastasis appeared at the right deltoid muscle. Genomic analysis of a sample of this metastasis confirmed PD-L1 positivity of greater than 50% with CD8⁺ T cells expression and showed MSI with a deleterious c.298C>T (p.R100*) MLH1 gene mutation. Multiplex ligation-dependent probe amplification (MLPA) of this sample unveiled MLH1 gene promoter methylation. The MLH1 gene mutation and the MLH1 gene methylation were not present at the germline setting.

CONCLUSIONS

In this particular case, we show that ARID1A gene mutations with sporadic MSI due to somatic MLH1 gene promoter methylation and MLH1 gene mutation could change the prognosis and define the response to immunotherapy in a patient with lung adenocarcinoma. Comprehensive solid and liquid biopsy tests are useful to find out resistance mechanisms to immune checkpoint inhibitors. Our data encourages the development of new therapies against ARID1A mutations and epigenomic methylation when involved in MSI neoplasms.

Dual Role of the PTPN13 Tyrosine Phosphatase in Cancer

In this review article, we present the current knowledge on PTPN13, a class I non-receptor protein tyrosine phosphatase identified in 1994. We focus particularly on its role in cancer, where PTPN13 acts as an oncogenic protein and also a tumor suppressor. To try to understand these apparent contradictory functions, we discuss PTPN13 implication in the FAS and oncogenic tyrosine kinase signaling pathways and in the associated biological activities, as well as its post-transcriptional and epigenetic regulation. Then, we describe PTPN13 clinical significance as a prognostic marker in different cancer types and its impact on anti-cancer treatment sensitivity. Finally, we present future research axes following recent findings on its role in cell junction regulation that implicate PTPN13 in cell death and cell migration, two major hallmarks of tumor formation and progression.

PTPN13 acts as a tumor suppressor in clear cell renal cell carcinoma by inactivating Akt signaling

Protein tyrosine phosphatase, nonreceptor type 13 (PTPN13), has emerged as a critical cancer-related gene that is implicated in a wide range of cancer types. However, the role of PTPN13 in clear cell renal cell carcinoma (ccRCC) is poorly understood. In the present study, we aimed to evaluate whether PTPN13 participates in the progression of ccRCC. Decreased expression of PTPN13 was found in ccRCC tissues, which predicted a shorter survival rate in ccRCC patients. PTPN13 expression was also lower in ccRCC cell lines, and the upregulation of PTPN13 repressed the proliferation, colony formation and invasion, but enhanced the apoptosis of ccRCC cells. In contrast, the silencing of PTPN13 produced the opposite effects. Further data showed that PTPN13 overexpression decreased the phosphorylation of Akt, while PTPN13 silencing increased the phosphorylation of Akt. Treatment with Akt inhibitor markedly abrogated the PTPN13 silencing-evoked oncogenic effect in ccRCC cells. Xenograft tumor experiments revealed that overexpression of PTPN13 remarkably restricted the tumor formation and growth of ccRCC cells in vivo associated with inactivation of Akt. In conclusion, our data demonstrated that overexpression of PTPN13 restricts the proliferation and invasion of ccRCC cells through inactivation of Akt. Our study suggests a tumor suppressive function of PTPN13 in ccRCC and highlights the potential role of PTPN13 in the progression of ccRCC.

Collapse of DNA Tetrahedron Nanostructure for "Off-On" Fluorescence Detection of DNA Methyltransferase Activity

As a potential detection technique, highly rigid and versatile functionality of DNA tetrahedron nanostructures is often used in biosensing systems. In this work, a novel multifunctional nanostructure has been developed as an "off-on" fluorescent probe for detection of target methyltransferase by integrating the elements of DNA tetrahedron, target recognition, and dual-labeled reporter. This sensing system is initially in an "OFF" state owing to the close proximity of fluorophores and quenchers. After the substrate is recognized by target methyltransferase, the DNA tetrahedron can be methylated to produce methylated DNA sites. These sites can be recognized and cut by the restriction endonuclease DpnI to bring about the collapse of the DNA tetrahedron, which leads to the separation of the dual-labeled reporters from the quenchers, and thus the recovery of fluorescence signal to produce an "ON" state. The proposed DNA tetrahedron-based sensing method can detect Dam methyltransferase in the range of 0.1-90 U mL^-1 with a detection limit of 0.045 U mL^-1 and shows good specificity and reproducibility for detection of Dam methyltransferase in a real sample. It has been successfully applied for screening various methylation inhibitors. Thus, this work possesses a promising prospect for detection of DNA methyltransfrase in the field of clinical diagnostics.