Low-dose DNA-demethylating agent enhances the chemosensitivity of cancer cells by targeting cancer stem cells via the upregulation of microRNA-497

The translational potential of epigenetic modulatory bioactive phytochemicals as adjuvant therapy against cancer

In preclinical studies, bioactive phytochemicals have shown enormous potential therapeutic efficacy against various human malignancies. These natural compounds have been shown to possess an inherent potential to alter the molecular signaling pathways and epigenetic modulatory activity involved in multiple physiological functions. Recently, epigenetic therapy has emerged as an important therapeutic modality due to the reversible nature of epigenetic alterations. To date, epigenetic modulatory compounds, for example, DNA methyltransferase inhibitors 5-azacytidine and 5'-deoxyazacytidine, as well as histone deacetylase inhibitors Vorinostat, Romidepsin, and Belinostat (PXD101), have been clinically approved by the FDA for the treatment of patients of leukemia and myelodysplastic syndrome. However, these synthetic epigenetic inhibitors are not as effective against many of the solid tumors. Therefore, the epigenetic modulatory phytochemicals provide new hope for improving the treatment modality as neoadjuvant and adjuvant therapy. It has been established that targeting more than one protein in the transformed cells simultaneously, that is, the multi-targeted therapeutic approach, might invoke a better therapeutic response. Therefore, here, we are compiling diverse evidences of the translational potential of novel combinatorial approaches utilizing the epigenetic modulatory phytochemicals with available therapeutics in the course of cancer treatment.

The efficacy of sorafenib against hepatocellular carcinoma is enhanced by 5-aza-mediated inhibition of ID1 promoter methylation

Sorafenib resistance greatly restricts its clinical application in patients with hepatocellular carcinoma (HCC). Numerous studies have reported that ID1 exerts a crucial effect in cancer initiation and development. Our previous research revealed an inhibitory role of ID1 in sorafenib resistance. However, the upstream regulatory mechanism of ID1 expression is unclear. Here, we discovered that ID1 expression is negatively correlated with promoter methylation, which is regulated by DNMT3B. Knockdown of DNMT3B significantly inhibited ID1 methylation status and resulted in an increase of ID1 expression. The demethylating agent 5-aza-2'-deoxycytidine (5-aza) remarkably upregulated ID1 expression. The combination of 5-aza with sorafenib showed a synergistic effect on the inhibition of cell viability.

Enhanced Survival of High-Risk Medulloblastoma-Bearing Mice after Multimodal Treatment with Radiotherapy, Decitabine, and Abacavir

Children with high-risk SHH/TP53-mut and Group 3 medulloblastoma (MB) have a 5-year overall survival of only 40%. Innovative approaches to enhance survival while preventing adverse effects are urgently needed. We investigated an innovative therapy approach combining irradiation (RT), decitabine (DEC), and abacavir (ABC) in a patient-derived orthotopic SHH/TP53-mut and Group 3 MB mouse model. MB-bearing mice were treated with DEC, ABC and RT. Mouse survival, tumor growth (BLI, MRT) tumor histology (H/E), proliferation (Ki-67), and endothelial (CD31) staining were analyzed. Gene expression was examined by microarray and RT-PCR (Ki-67, VEGF, CD31, CD15, CD133, nestin, CD68, IBA). The RT/DEC/ABC therapy inhibited tumor growth and enhanced mouse survival. Ki-67 decreased in SHH/TP53-mut MBs after RT, DEC, RT/ABC, and RT/DEC/ABC therapy. CD31 was higher in SHH/TP53-mut compared to Group 3 MBs and decreased after RT/DEC/ABC. Microarray analyses showed a therapy-induced downregulation of cell cycle genes. By RT-PCR, no therapy-induced effect on stem cell fraction or immune cell invasion/activation could be shown. We showed for the first time that RT/DEC/ABC therapy improves survival of orthotopic SHH/TP53-mut and Group 3 MB-bearing mice without inducing adverse effects suggesting the potential for an adjuvant application of this multimodal therapy approach in the human clinic.

Combination of Decitabine and a Modified Regimen of Cisplatin, Cytarabine and Dexamethasone: A Potential Salvage Regimen for Relapsed or Refractory Diffuse Large B-Cell Lymphoma After Second-Line Treatment Failure

Objective

The prognosis for patients with relapsed or refractory diffuse large B-cell lymphoma (R/R-DLBCL) after second-line treatment failure is extremely poor. This study prospectively observed the efficacy and safety of decitabine with a modified cisplatin, cytarabine, and dexamethasone (DHAP) regimen in R/R-DLBCL patients who failed second-line treatment.

Methods

Twenty-one R/R-DLBCL patients were enrolled and treated with decitabine and a modified DHAP regimen. The primary endpoints were overall response rate (ORR) and safety. The secondary endpoints were progression-free survival (PFS) and overall survival (OS).

Results

ORR reached 50% (complete response rate, 35%), five patients (25%) had stable disease (SD) with disease control rate (DCR) of 75%. Subgroup analysis revealed patients over fifty years old had a higher complete response rate compared to younger patients (P = 0.005), and relapsed patients had a better complete response rate than refractory patients (P = 0.031). Median PFS was 7 months (95% confidence interval, 5.1-8.9 months). Median OS was not achieved. One-year OS was 59.0% (95% CI, 35.5%-82.5%), and two-year OS was 51.6% (95% confidence interval, 26.9%-76.3%). The main adverse events (AEs) were grade 3/4 hematologic toxicities such as neutropenia (90%), anemia (50%), and thrombocytopenia (70%). Other main non-hematologic AEs were grade 1/2 nausea/vomiting (40%) and infection (50%). No renal toxicity or treatment-related death occurred.

Conclusion

Decitabine with a modified DHAP regimen can improve the treatment response and prognosis of R/R-DLBCL patients with good tolerance to AEs, suggesting this regimen has potential as a possible new treatment option for R/R-DLBCL patients after second-line treatment failure.

Clinical Trial Registration

ClinicalTrials.gov, identifier: NCT03579082.

miR-455 Inhibits the Viability and Invasion by Targeting RAB18 in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) has been regarded as the fifth most common cancer worldwide with a low prognosis. miR-455 usually played the role of a tumor suppressor in multiple cancers. The aim of this study was to investigate the roles of miR-455 in HCC.

Materials and Methods

Cell viability and invasion were measured by CCK8 and Transwell assays. Luciferase reporter assay was performed to verify that miR-455 directly binds to the 3′-noncoding region (UTR) of RAB18 mRNA in Huh7 cells.

Results

The expression of miR-455 was lower in HCC tissues and cell lines than in nontumor tissues and normal cell line, and downregulation of miR-455 was connected with worse outcome of HCC patients. miR-455 suppressed cell proliferation in vitro and in vivo, and it inhibited the abilities of cell invasion and EMT in HCC. RAB18 was upregulated in HCC tissues and cell lines, and the expression of RAB18 was regulated by miR-455. RAB18 reversed partial roles of miR-455 on cell viability and invasion in HCC.

Conclusion

miR-455 inhibited cell viability and invasion by directly targeting the 3′-UTR of RAB18 mRNA of hepatocellular carcinoma.

Zebularine elevates STING expression and enhances cGAMP cancer immunotherapy in mice

DNA methylation abnormality is closely related to tumor occurrence and development. Chemical inhibitors targeting DNA methyltransferase (DNMTis) have been used in treating cancer. However, the impact of DNMTis on antitumor immunity has not been well elucidated. In this study, we show that zebularine (a demethylating agent) treatment of cancer cells led to increased levels of interferon response in a cyclic guanosine monophosphate-AMP (cGAMP) synthase (cGAS)- and stimulator of interferon genes (STING)-dependent manner. This treatment also specifically sensitized the cGAS-STING pathway in response to DNA stimulation. Incorporation of zebularine into genomic DNA caused demethylation and elevated expression of a group of genes, including STING. Without causing DNA damage, zebularine led to accumulation of DNA species in the cytoplasm of treated cells. In syngeneic tumor models, administration of zebularine alone reduced tumor burden and extended mice survival. This effect synergized with cGAMP and immune checkpoint blockade therapy. The efficacy of zebularine was abolished in nude mice and in cGAS^-/- or STING^-/- mice, indicating its dependency on host immunity. Analysis of tumor cells indicates upregulation of interferon-stimulated genes (ISGs) following zebularine administration. Zebularine promoted infiltration of CD8 T cells and natural killer (NK) cells into tumor and therefore suppressed tumor growth. This study unveils the role of zebularine in sensitizing the cGAS-STING pathway to promote anti-tumor immunity and provides the foundation for further therapeutic development.

Phase I clinical trial of decitabine (5-aza-2'-deoxycytidine) administered by hepatic arterial infusion in patients with unresectable liver-predominant metastases

DNA demethylating agents may increase the immunogenicity of malignant tumours and increase the efficacy of subsequent treatment with immune check point inhibitors. We investigated the safety of administrating the demethylating agent decitabine by hepatic arterial infusionin patients with unresectable liver meta stases from solid tumours in a dose escalation phase I clinical trial. A total of nine eligible patients were enrolled and initiated study treatment at three different dose levels (two patients at 10, four at 15 and six at a dose level of 20mg decitabine/m2/day) (per protocol there was no intent to escalate the dose above the median tolerated intravenous dose level). Decitabine was administered as a 1-hour hepatic arterial infusion on five consecutive days every 4 weeks. Intrapatient dose escalation was applied in five patients. Grades 1 and 2 haematological toxicity was the most frequent treatment-related adverse event. None of the patients experienced treatment-limiting adverse events. Expression analysis of 30 cancer test is antigens (CTA) in pretreatment and post-treatment biopsies from patients indicated an increased expression of 21 CTAs after treatment. There were no objective tumour responses on study treatment or during post study exposure to immune checkpoint therapy in four patients with uveal melanoma liver metastases. We conclude that the investigate d hepatic arterial administration regimen for decitabine can be safely applied, and a dose level of 20 mg/m2/day on five consecutive days every 4 weeks can be considered for further investigation in combinatorial immunotherapy regimens.

Phase Ib/II study of safety and efficacy of low-dose decitabine-primed chemoimmunotherapy in patients with drug-resistant relapsed/refractory alimentary tract cancer

The pressing need for improved therapeutic outcomes provides a good rationale for identifying effective strategies for alimentary tract (AT) cancer treatment. The potential re-sensitivity property to chemo- and immunotherapy of low-dose decitabine has been evident both preclinically and in previous phase I trials. We conducted a phase Ib/II trial evaluating low-dose decitabine-primed chemoimmunotherapy in patients with drug-resistant relapsed/refractory (R/R) esophageal, gastric or colorectal cancers. Forty-five patients received either the 5-day decitabine treatment with subsequent readministration of the previously resistant chemotherapy (decitabine-primed chemotherapy, D-C cohort) or the aforementioned regimen followed by cytokine-induced killer cells therapy (D-C and cytokine-induced killer [CIK] cell treatment, D-C + CIK cohort) based on their treatment history. Grade 3 to 4 adverse events (AEs) were reported in 11 (24.4%) of 45 patients. All AEs were controllable, and no patient experienced a treatment-related death. The objective response rate (ORR) and disease control rate (DCR) were 24.44% and 82.22%, respectively, including two patients who achieved durable complete responses. Clinical response could be associated with treatment-free interval and initial surgical resection history. ORR and DCR reached 28% and 92%, respectively, in the D-C + CIK cohort. Consistently, the progression-free survival (PFS) of the D-C + CIK cohort compared favorably to the best PFS of the pre-resistant unprimed therapy (p = 0.0001). The toxicity and ORRs exhibited were non-significantly different between cancer types and treatment cohort. The safety and efficacy of decitabine-primed re-sensitization to chemoimmunotherapy is attractive and promising. These data warrant further large-scale evaluation of drug-resistant R/R AT cancer patients with advanced stage disease.

MicroRNA-214-3p inhibits proliferation and cell cycle progression by targeting MELK in hepatocellular carcinoma and correlates cancer prognosis

Background

MicroRNAs are considered as potential regulators in various biological pathways and contribute to the diagnosis and prognosis of cancers. MicroRNA-214-3p (miR-214-3p) was proved to be correlated with various cancers in recent studies. However, the biological functions of miR-214-3p in hepatocellular carcinoma (HCC) and its association with the prognosis of HCC after liver transplantation are still unevaluated. Here we intended to elucidate the functional implication of miR-214-3p in regulation of cell proliferation and apoptosis and its potential prediction of clinical prognosis of HCC patients.

Methods

Expressions of miR-214-3p in 98 HCC patients and three HCC cell lines were detected by quantitative reverse transcription PCR (qRT-PCR) to explore the association of miR-214-3p expression and clinicopathological characteristics. The effects of miR-214-3p on cell proliferation and apoptosis were examined by proliferation and flow cytometry assay, respectively. The direct target gene of miR-214-3p was also detected by luciferase reporter assay.

Results

The effects of miR-214-3p on cell proliferation and apoptosis were examined by proliferation and flow cytometry assay, respectively. The direct target gene of miR-214-3p was also detected by luciferase reporter assay. The results showed that miR-214-3p expression was downregulated in primary HCC samples compared with normal liver tissues, and was decreased in HCC recurrence species compared with non-recurrence controls (P = 0.001). Low miR-214-3p level was associated with poor overall survival (OS) (Log rank P = 0.003) and recurrence-free survival (RFS) (Log rank P = 0.007). Moreover, miR-214-3p precursor transfection resulted in decreased cell proliferation, cell cycle arrest at G1 phase, and enhanced cell apoptosis in HepG2 and HUH-7 cells. Further investigation showed that miR-214-3p could regulate its target gene maternal embryonic leucine zipper kinase (MELK) by directly binding to MELK-3′-UTR.

Conclusions

miR-214-3p suppresses HCC progression by directly down-regulating MELK expression, indicating a potential therapeutic target for the treatment and prognosis of HCC patients.

Paradoxical roles of dual oxidases in cancer biology

Dysregulated oxidative metabolism is a well-recognized aspect of cancer biology, and many therapeutic strategies are based on targeting cancers by altering cellular redox pathways. The NADPH oxidases (NOXes) present an important enzymatic source of biological oxidants, and the expression and activation of several NOX isoforms are frequently dysregulated in many cancers. Cell-based studies have demonstrated a role for several NOX isozymes in controlling cell proliferation and/or cell migration, further supporting a potential contributing role for NOX in promoting cancer. While various NOX isoforms are often upregulated in cancers, paradoxical recent findings indicate that dual oxidases (DUOXes), normally prominently expressed in epithelial lineages, are frequently suppressed in epithelial-derived cancers by epigenetic mechanisms, although the functional relevance of such DUOX silencing has remained unclear. This review will briefly summarize our current understanding regarding the importance of reactive oxygen species (ROS) and NOXes in cancer biology, and focus on recent observations indicating the unique and seemingly opposing roles of DUOX enzymes in cancer biology. We will discuss current knowledge regarding the functional properties of DUOX, and recent studies highlighting mechanistic consequences of DUOX1 loss in lung cancer, and its consequences for tumor invasiveness and current anticancer therapy. Finally, we will also discuss potentially unique roles for the DUOX maturation factors. Overall, a better understanding of mechanisms that regulate DUOX and the functional consequences of DUOX silencing in cancer may offer valuable new diagnostic insights and novel therapeutic opportunities.

Clinical and biological effects of demethylating agents on solid tumours - A systematic review

BACKGROUND

It is assumed that DNA methylation plays a key role in both tumour development and therapy resistance. Demethylating agents have been shown to be effective in the treatment of haematological malignancies. Based on encouraging preclinical results, demethylating agents may also be effective in solid tumours. This systematic review summarizes the evidence of the effect of demethylating agents on clinical response, methylation and the immune system in solid tumours.

METHODS

We conducted a systematic literature search from 1949 to December 2016, according to the PRISMA guidelines. Studies which evaluated treatment with azacitidine, decitabine, guadecitabine, hydralazine, procaine, MG98 and/or zebularine in patients with solid tumours were included. Data on clinical response, effects on methylation and immune response were extracted.

RESULTS

Fifty-eight studies were included: in 13 studies complete responses (CR) were observed, 35 studies showed partial responses (PR), 47 studies stable disease (SD) and all studies except two showed progressive disease (PD). Effects on global methylation were observed in 11/15 studies and demethylation/re-expression of tumour specific genes was seen in 15/17 studies. No clear correlation between (de)methylation and clinical response was observed. In 14 studies immune-related responses were reported, such as re-expression of cancer-testis antigens and upregulation of interferon genes.

CONCLUSION

Demethylating agents are able to improve clinical outcome and alter methylation status in patients with solid tumours. Although beneficial effect has been shown in individual patients, overall response is limited. Further research on biomarker predicting therapy efficacy is indicated, particularly in earlier stage and highly methylated tumours.

Interactions between anticancer active platinum complexes and non-coding RNAs/microRNAs

Platinum(II) complexes such as cisplatin, carboplatin and oxaliplatin are clinically approved for the therapy of various solid tumors. Challenging pathogenic properties of cancer cells and the response of cancers towards platinum-based drugs are strongly influenced by non-coding small RNA molecules, the microRNAs (miRNAs). Both increased platinum activity and formation of tumor resistance towards platinum drugs are controlled by miRNAs. This review gives an overview of the interactions between platinum-based drugs and miRNAs, and their influence on platinum activity in various cancer types is discussed.

Current state of phenolic and terpenoidal dietary factors and natural products as non-coding RNA/microRNA modulators for improved cancer therapy and prevention

The epigenetic regulation of cancer cells by small non-coding RNA molecules, the microRNAs (miRNAs), has raised particular interest in the field of oncology. These miRNAs play crucial roles concerning pathogenic properties of cancer cells and the sensitivity of cancer cells towards anticancer drugs. Certain miRNAs are responsible for an enhanced activity of drugs, while others lead to the formation of tumor resistance. In addition, miRNAs regulate survival and proliferation of cancer cells, in particular of cancer stem-like cells (CSCs), that are especially drug-resistant and, thus, cause tumor relapse in many cases. Various small molecule compounds were discovered that target miRNAs that are known to modulate tumor aggressiveness and drug resistance. This review comprises the effects of naturally occurring small molecules (phenolic compounds and terpenoids) on miRNAs involved in cancer diseases.