Arsenic trioxide reduces the expression of E2F1, cyclin E, and phosphorylation of PI3K signaling molecules in acute leukemia cells

Arsenic Trioxide Decreases Lymphangiogenesis by Inducing Apoptotic Pathways and Inhibition of Important Endothelial Cell Receptors

Tumor-induced lymphangiogenesis is strongly associated with the formation of tumor metastasis. Therefore, the regulation of lymphangiogenesis offers a promising target in cancer therapy. Arsenic trioxide (ATO) is highly effective in the treatment of patients with acute promyelocytic leukemia (APL). As ATO mediates anti-angiogenic effects on endothelial and tumor cells, we aimed to explore the impact of ATO on lymphangiogenesis in human lymphatic endothelial cells (LEC). The BrdU assay and flow cytometry analysis were used to evaluate the influence of ATO on the proliferation and cell cycle distribution of LECs. The lymphatic suppression effects of ATO were investigated in vitro using the lymphatic tube formation assay. The effects of ATO on apoptosis, mitochondrial membrane potential and endothelial cell receptors were investigated by Western blotting, ELISA, flow cytometry and qRT-PCR. The treatment of LECs with ATO attenuated cell proliferation, blocked tube formation and induced subG0/G1 arrest in LECs, thus suggesting enhanced apoptosis. Although subG0/G1 arrest was accompanied by the upregulation of p21 and p53, ATO treatment did not lead to visible cell cycle arrest in LECs. In addition, ATO caused apoptosis via the release of cytochrome c from mitochondria, activating caspases 3, 8 and 9; downregulating the anti-apoptotic proteins survivin, XIAP and cIAP-2; and upregulating the pro-apoptotic protein Fas. Furthermore, we observed that ATO inhibited the VEGF-induced proliferation of LECs, indicating that pro-survival VEGF/VEGFR signaling was affected by ATO treatment. Finally, we found that ATO inhibited the expression of the important endothelial cell receptors VEGFR-2, VEGFR-3, Tie-2 and Lyve-1. In conclusion, we demonstrate that ATO inhibits lymphangiogenesis by activating apoptotic pathways and inhibiting important endothelial cell receptors, which suggests that this drug should be further evaluated in the treatment of tumor-associated lymphangiogenesis.

Mechanistic update of Trisenox in blood cancer

Acute promyelocytic leukemia (APL)/blood cancer is M3 type of acute myeloid leukemia (AML) formed inside bone marrow through chromosomal translocation mutation usually between chromosome 15 & 17. It accounts around 10% cases of AML worldwide. Trisenox (TX/ATO) is used in chemotherapy for treatment of all age group of APL patients with highest efficacy and survival rate for longer period. High concentration of TX inhibits growth of APL cells by diverse mechanism however, it cures only PML-RARα fusion gene/oncogene containing APL patients. TX resistant APL patients (different oncogenic make up) have been reported from worldwide. This review summarizes updated mechanism of TX action via PML nuclear bodies formation, proteasomal degradation, autophagy, p53 activation, telomerase activity, heteromerization of pRb & E2F, and regulation of signaling mechanism in APL cells. We have also provided important information of combination therapy of TX with other molecules mechanism of action in acute leukemia cells. It provides updated information of TX action for researcher which may help finding new target for further research in APL pathophysiology or new TX resistant APL patients drug designing.

The application of arsenic trioxide in cancer: An umbrella review of meta-analyses based on randomized controlled trials

ETHNOPHARMACOLOGICAL RELEVANCE

Processed from natural minerals, arsenic trioxide (ATO) as an ancient Chinese medicine has been used to treat diseases for over 2000 years. And it was applied to treat acute promyelocytic leukemia (APL) since the 1970s in China. Summarizing the clinical evidence of ATO in cancer is conducive to further understanding, development, and promotion of its pharmacological research.

AIM OF THE STUDY

It is the first time to comprehensively assess and summarize the evidence of ATO in cancer treatment via umbrella review.

MATERIALS AND METHODS

8 databases in English or Chinese from their inception to February 21, 2023 were searched by two reviewers separately and suitable meta-analyses (MAs) were included in this umbrella review. Their methodological quality and risk of bias were evaluated and data of outcomes was extracted and pooled again. The evidence certainty of pooled results was classified.

RESULTS

17 MAs with 27 outcomes and seven comparisons in three cancers were included in this umbrella review. However, their methodological quality was unsatisfactory with 6 MAs as low quality and 12 MAs as critically low quality. Their shortcomings were mainly focused on protocol, literature selecting, bias risk, small sample study bias, and conflicts of interest or funding. And they were all assessed as high risk in bias. It was suggested that ATO had an advantage in enhancing complete remission rate, event-free survival, and recurrence free survival and decreasing recurrence rate, cutaneous toxicity, hyper leukocyte syndrome, tretinoin syndrome, edema and hepatotoxicity in different comparisons of APL with low or moderate certainty. Besides, compared with transcatheter arterial chemoembolization (TACE) alone, ATO plus TACE also could improve objective response rate, disease control rate, survival rate (0.5, 1, 2, and 3-year) and life quality and reduce the level of alpha fetoprotein in primarily hepatocellular carcinoma with low or moderate certainty. However, no significant results were found in MM. Finally, key findings were as followed. ATO has potential broad-spectrum anticancer effects but the clinical transformation is rarely achieved. Route of administration may affect the antitumor effects of ATO. ATO can act synergistically in combination with a variety of antitumor therapies. The safety and drug resistance of ATO should be paid more attention to.

CONCLUSIONS

ATO may be a promising drug in anticancer treatment although earlier RCTs have dragged down the level of evidence. However, high-quality clinical trials are expected to explore its broad-spectrum anticancer effects, wide application, appropriate route of administration, and compound dosage form.

Aa-Z2 triggers ROS-induced apoptosis of osteosarcoma by targeting PDK-1

BACKGROUND

Osteosarcoma (OS) is the most frequent cancer derived from bone, and the prognosis of OS is poor. Metabolic alterations have been previously reported to contribute to the development of OS, and arsenic compounds have been suggested to exhibit strong anti-OS effects. However, few studies have described the therapeutic efficiency of arsenic compounds by targeting metabolism in OS.

METHODS

Here, we presented a novel organo-arsenic compound, Aa-Z2, and its antitumour efficacy against OS both in vitro and in vivo.

RESULTS

Aa-Z2 induced OS cell apoptosis, G2/M phase arrest, and autophagy through the accumulation of reactive oxygen species (ROS). Elevated ROS functioned by promoting the mitochondrial-dependent caspase cascade and attenuating the PI3K/Akt/mTOR signalling pathway. N-acetylcysteine (NAC), a kind of ROS scavenger, could reverse the effects of Aa-Z2 treatment on 143B and HOS cells. Specifically, by targeting pyruvate dehydrogenase kinase 1 (PDK-1), Aa-Z2 induced changes in mitochondrial membrane potential and alterations in glucose metabolism to accumulate ROS. Overexpression of PDK-1 could partially desensitize OS cells to Aa-Z2 treatment. Importantly, Aa-Z2 suppressed tumour growth in our xenograft osteosarcoma model.

CONCLUSION

The study provides new insights into the mechanism of Aa-Z2-related metabolic alterations in OS inhibition, as well as pharmacologic evidence supporting the development of metabolism-targeting therapeutics.

p53 as a unique target of action of cisplatin in acute leukaemia cells

Acute promyelocytic leukaemia (APL) occurs in approximately 10% of acute myeloid leukaemia patients. Arsenic trioxide (ATO) has been for APL chemotherapy, but recently several ATO‐resistant cases have been reported worldwide. Cisplatin (CDDP) enhances the toxicity of ATO in ovarian, lung cancer, chronic myelogenous leukaemia, and HL‐60 cells. Hence, the goal of this study was to investigate a novel target of CDDP action in APL cells, as an alternate option for the treatment of ATO‐resistant APL patients. We applied biochemical, molecular, confocal microscopy and advanced gene editing (CRISPR‐Cas9) techniques to elucidate the novel target of CDDP action and its functional mechanism in APL cells. Our main findings revealed that CDDP activated p53 in APL cells through stress signals catalysed by ATM and ATR protein kinases, CHK1 and CHK2 phosphorylation at Ser 345 and Thr68 residues, and downregulation and dissociation of MDM2‐DAXX‐HAUSP complex. Our functional studies confirmed that CDDP‐induced repression of MDM2‐DAXX‐HAUSP complex was significantly reversed in both nutilin‐3‐treated KG1a and p53‐knockdown NB4 cells. Our findings also showed that CDDP stimulated an increased number of promyelocytes with dense granules, activated p53 expression, and downregulated MDM2 in liver and bone marrow of APL mice. Principal conclusion of our study highlights a novel mode of action of CDDP targeting p53 expression which may provide a basis for designing new anti‐leukaemic compounds for treatment of APL patients.