Genotoxic and antigenotoxic potential of amygdalin on isolated human lymphocytes by the comet assay

UHRF1 poly-auto-ubiquitination induced by the anti-cancer drug, thymoquinone, is involved in the DNA repair machinery recruitment

DNA methylation is one of the most important epigenetic mark involved in many physiologic cellular processes and pathologies. During mitosis, the transmission of DNA methylation patterns from a mother to the daughter cells is ensured through the action of the Ubiquitin-like, containing PHD and RING domains, 1/DNA methyltransferase 1 (UHRF1/DNMT1) tandem. UHRF1 is involved in the silencing of many tumor suppressor genes (TSGs) via mechanisms that remain largely to be deciphered. The present study investigated the role and the regulation of UHRF1 poly-ubiquitination induced by thymoquinone, a natural anti-cancer drug, known to enhance or re-activate the expression of TSGs. We found that the auto-ubiquitination of UHRF1, induced by TQ, is mediated by reactive oxygen species, and occurs following DNA damage. We demonstrated that the poly-ubiquitinated form of UHRF1 is K63-linked and can still silence the tumor suppressor gene p16INK4A/CDKN2A. We further showed that TQ-induced auto-ubiquitination is mediated via the activity of Tip60. Since this latter is known as a nuclear receptor co-factor, we investigated if the glucocorticoid receptor (GR) might be involved in the regulation of UHRF1 ubiquitination. Activation of the GR, with dexamethasone, did not influence auto-ubiquitination of UHRF1. However, we could observe that TQ induced a K48-linked poly-ubiquitination of GR, probably involved in the proteosomal degradation pathway. Mass-spectrometry analysis of FLAG-HA-tagged UHRF1 identified UHRF1 partners involved in DNA repair and showed that TQ increased their association with UHRF1, suggesting that poly-ubiquitination of UHRF1 is involved in the DNA repair process. We propose that poly-ubiquitination of UHRF1 serves as a scaffold to recruit the DNA repair machinery at DNA damage sites.

Amygdalin: A Review on Its Characteristics, Antioxidant Potential, Gastrointestinal Microbiota Intervention, Anticancer Therapeutic and Mechanisms, Toxicity, and Encapsulation

Bioactive amygdalin, found in high concentrations in bitter almonds, has been recognized as a symbol of the cyanogenic glycoside chemical organic substance, which was initially developed as a pharmaceutical for treating cancer after being hydrolyzed to hydrogen cyanide (HCN). Regrettably, research has shown that HCN can also damage normal cells, rendering it non-toxic to the human body. Extreme controversy surrounds both in vivo and in vitro studies, making its use risky. This review provides an extensive update on characteristics, antioxidant potential, gastrointestinal microbiota intervention, anticancer therapeutic, mechanisms, toxicity, and encapsulation of amygdalin. Antioxidant, anti-tumor, anti-fibrotic, antiatherosclerosis, anti-inflammatory, immunomodulatory, and analgesic characteristics, and the ability to improve digestive and reproductive systems, neurodegeneration, and cardiac hypertrophy are just some of the benefits of amygdalin. Studies verified the HCN-produced amygdalin to be harmful orally, but only at very high doses. Although intravenous treatment was less effective than the oral method, the oral route has a dose range of 0.6 to 1 g daily. Amygdalin’s toxicity depends heavily on the variety of bacteria in the digestive tract. Unfortunately, there is currently no foolproof method for determining the microbial consortium and providing a safe oral dosage for every patient. Amygdalin encapsulation in alginate-chitosan nanoparticles (ACNPs) is a relatively new area of research. Amygdalin has an enhanced cytotoxic effect on malignant cells, and ACNPs can be employed as an active drug-delivery system to release this compound in a regulated, sustained manner without causing any harm to healthy cells or tissues. In conclusion, a large area of research for a substance that might be the next step in cancer therapy is opened up due to unverified and conflicting data.

Determination of genotoxic damages of picloram and dicamba with comet assay in Allium cepa rooted in tissue culture and distilled water

BACKGROUND

Many genotoxicity tests allow us to understand the mechanism of damages on genetic material occurring in living organisms against various physical and chemical agents. One of them is the Comet test. The current study aimed to evaluate genotoxic caused by picloram and dicamba to root meristems of Allium cepa utilizing comet assay.

METHODS

Two different protocols were used for rooting and auxin/pesticide application. (i) A. cepa bulbs were rooted in MS medium and then treated with Murashige and Skoog (MS) medium (control) and 0.67, 1.34, 2.01, 2.68, 3.35, 4.02, and 8.04 mg/L of picloram and dicamba using aseptic tissue culture techniques. (ii) A. cepa bulbs were then rooted in bidistilled water and treated with 0 (control), 0.67, 1.34, 2.01, 2.68, 3.35, 4.02, and 8.04 mg/L of picloram and dicamba in distilled water. The A. cepa root tip cells in both treatment groups were examined using comet test to find the possible DNA damaging effects of picloram and dicamba.

RESULTS

The results obtained at all the concentrations were statistically compared with their control groups. Almost at all the concentrations of Picloram and dicamba increased comet tail intensity (%) and tail moment in roots treated in MS medium. Two highest concentrations revealed toxic effect. On the other hand, DNA damaging effect of both auxins was only noted on the highest (> 4.02 mg/L) in roots treated in distilled water.

CONCLUSIONS

This study approve and confirm genotoxic effects of how growth regulators on plants. These findings give an evidence of DNA damage in A. cepa. Therefore, both picloram and dicamba should only be used in appropriate and recommended concentrations in agriculture to conserve ecosystem and to pose minimum threat to life.

Genotoxic effects of gadobutrol and gadoversetamide active substances used in magnetic resonance imaging in human peripheral lymphocytes in vitro

Gadobutrol and gadoversetamide are gadolinium-based contrast agents (GBCAs) widely used during magnetic resonance imaging examination. In this study, the genotoxicity of two GBCAs, gadobutrol and gadoversetamide, was investigated by using different endpoints: chromosome aberration (CAs), sister chromatid exchange (SCEs), and micronucleus (MNi). Human peripheral lymphocytes (PBLs) were treated with five concentrations (7 000, 14 000, 28 000, 56 000, and 112 000 μg/mL) of both agents. While a few concentrations of gadobutrol significantly increased abnormal cell frequency and CA/Cell, nearly all the concentrations of gadoversetamide significantly elevated the same aberrations. Similarly, the effect of gadoversetamide on the formation of SCEs was higher than those of gadobutrol. Only one concentration of gadoversetamide significantly increased MN% but no gadobutrol. The comet assay was applied for the only gadobutrol which induced a significant increase in tail intensity at the highest concentration only. On the other hand, significantly decreased mitotic index (MI) was observed following both substances, again gadoversetamide was slightly higher than those of the gadobutrol. The results revealed that both the contrast agents are likely to induce genotoxic risk in PBLs. However, different concentrations and treatment periods should be examined in vitro and specifically in vivo with different test systems for the safer usage of these contrast agents.

In-vitro and in-vivo investigation of amygdalin, metformin, and combination of both against doxorubicin on hepatocellular carcinoma

AIM

Hepatocellular carcinoma (HCC) is a potentially life-threatening cancer. In the current study, anti-HCC efficacy of amygdalin, or metformin alone or in combination in comparison to doxorubicin was studied.

MAIN METHODS

Both in-vitro and in-vivo based models. HepG-2 and Huh-7 cell lines as established in-vitro model for HCC were treated with different concentrations of indicated drugs to evaluate the cytotoxicity and determine IC₅₀ for 24, 48 and 72 h. Moreover, the effect of different treatments on apoptosis and cell cycle using flow cytometric analysis were studied. Hepatocellular carcinoma induced in rats by diethyl-nitrosamine and carbon tetrachloride was established, to further investigate the efficacy of indicated drugs. Aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase were measured by spectrophotometer, alpha-fetoprotein, cytochrome-c, caspase-3 and malondialdehyde were measured by ELISA, and liver biopsies were also evaluated histopathologically.

KEY FINDINGS

In-vitro results showed that the combination has a promising effect when compared to amygdalin or metformin alone as it is more cytotoxic and have higher ability for induction of apoptosis and arresting cell cycle. In-vivo doxorubicin has a good effect for treating HCC. Also, the combination showed a promising prognostic effect depending on the cytotoxic activity and tumor marker when compared to amygdalin or metformin alone.

SIGNIFICANCE

Based on the current data, it was hypothesized that amygdalin and metformin especially when used in combination will be a promising approach with low side effects for enhancement of HCC.