RESUMEN

BACKGROUND: This study evaluated the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of 8-chloro-adenosine (8-Cl-Ado) in patients with relapsed/refractory acute myeloid leukemia (AML). METHODS: 8-Cl-Ado was administered daily for 5 days; the starting dose was 100 mg/m2 , the highest dose tested was 800 mg/m2 . The end points were toxicity, disease response, and PK/PD measurements. RESULTS: The predominant nonhematologic toxicity was cardiac with grade ≥3 toxicity. Plasma PK in all patients suggested heterogeneity among patients, yet, some dose-dependency for the accumulation of 8-Cl-Ado. Two 8-Cl-Ado metabolites accumulated at similar levels to 8-Cl-Ado. Cellular PK in eight patients indicated accumulation of 8-Cl-ATP, which was associated with AML blast cytoreduction in peripheral blood. The authors determined the RP2D of 8-Cl-Ado to be 400 mg/m2 . CONCLUSIONS: Given the cardiac adverse events observed, patients require monitoring for arrhythmias and QT interval during infusion. Although peripheral blood cytoreduction was observed, responses were transient, suggesting combination strategies will be required.

Asunto(s)

RESUMEN

BACKGROUND/AIM: Cholangiocarcinoma is a lethal cancer, and current chemotherapeutic drugs are not very effective. Recent studies reported that cholangiocarcinoma cells were sensitive to adenosine. One adenosine analog, 8-chloroadenosine (8-CA), was shown to be more potent than adenosine and induced apoptosis in leukemia cells. This study examined effects of 8-CA in cholangiocarcinoma cells and immortalized cholangiocytes. MATERIALS AND METHODS: Cell growth was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell invasion was examined by transwell assay. Cell cycle and cell death were evaluated by flow cytometry. Colorimetric absorbance assay was used to assessed RNA and protein synthesis as well as mitochondrial membrane potential. Protein levels were examined by western blot analysis. Animal experiment was performed in Balb/cAJcl-Nu mice. RESULTS: 8-CA reduced cholangiocarcinoma cell growth, prevented colony formation and caused endoplasmic reticulum stress and cell-cycle arrest. Eventually, apoptosis was induced. However, treatment with 8-CA did not interfere with RNA synthesis or protein synthesis and did not alter mitochondrial membrane potential. Combination of 8-CA with several chemotherapeutic drugs in vitro was less effective than 8-CA alone and the drugs alone, except for the combination of 8-CA with hydroxychloroquine, which had an additive effect on RMCCA-1 cells. However, further in vivo study showed that treatment with 8-CA alone inhibited tumor growth more than treatment with a combination of 8-CA with hydroxychloroquine. CONCLUSION: 8-Chloroadenosine inhibited CCA cells by inducing endoplasmic reticulum stress and apoptosis. In vivo study showed that 8-CA inhibited cholangiocarcinoma tumor growth better when administered alone as compared to a combination with hydroxychloroquine.

Asunto(s)

RESUMEN

Chronic myeloid leukemia (CML) is effectively treated with tyrosine kinase inhibitors (TKIs), targeting the BCR::ABL1 oncoprotein. Still, resistance to therapy, relapse after treatment discontinuation, and side effects remain significant issues of long-term TKI treatment. Preliminary studies have shown that targeting oxidative phosphorylation (oxPhos) and the unfolded protein response (UPR) are promising therapeutic approaches to complement CML treatment. Here, we tested the efficacy of different TKIs, combined with the ATP synthase inhibitor oligomycin and the ER stress inducer thapsigargin in the CML cell lines K562, BV173, and KU812 and found a significant increase in cell death. Both, oligomycin and thapsigargin, triggered the upregulation of the UPR proteins ATF4 and CHOP, which was inhibited by imatinib. We observed comparable effects on cell death when combining TKIs with the ATP synthase inhibitor 8-chloroadenosine (8-Cl-Ado) as a potentially clinically applicable therapeutic agent. Stress-related apoptosis was triggered via a caspase cascade including the cleavage of caspase 3 and the inactivation of poly ADP ribose polymerase 1 (PARP1). The inhibition of PARP by olaparib also increased CML death in combination with TKIs. Our findings suggest a rationale for combining TKIs with 8-Cl-Ado or olaparib for future clinical studies in CML.

Asunto(s)

RESUMEN

It is known that 8-chloro-adenosine (8-Cl-Ado) is a novel RNA-directed nucleoside analog that targets leukemic stem cells (LSCs). In a phase I clinical trial with 8-Cl-Ado in patients with refractory or relapsed (R/R) AML, we observed encouraging but short-lived clinical responses, likely due to intrinsic mechanisms of LSC resistance. LSC homeostasis depends on amino acid-driven and/or fatty acid oxidation (FAO)-driven oxidative phosphorylation (OXPHOS) for survival. We recently reported that 8-Cl-Ado and the BCL-2-selective inhibitor venetoclax (VEN) synergistically inhibit FAO and OXPHOS in LSCs, thereby suppressing acute myeloid leukemia (AML) growth in vitro and in vivo. Herein, we report that 8-Cl-Ado inhibits ribosomal RNA (rRNA) synthesis through the downregulation of transcription initiation factor TIF-IA that is associated with increasing levels of p53. Paradoxically, 8-Cl-Ado-induced p53 increased FAO and OXPHOS, thereby self-limiting the activity of 8-Cl-Ado on LSCs. Since VEN inhibits amino acid-driven OXPHOS, the addition of VEN significantly enhanced the activity of 8-Cl-Ado by counteracting the self-limiting effect of p53 on FAO and OXPHOS. Overall, our results indicate that VEN and 8-Cl-Ado can cooperate in targeting rRNA synthesis and OXPHOS and in decreasing the survival of the LSC-enriched cell population, suggesting the VEN/8-Cl-Ado regimen as a promising therapeutic approach for patients with R/R AML.

RESUMEN

8-Chloro-adenosine (8-Cl-Ado) is currently in phase I clinical trial. Activation of p53 and transactivation of p21 regulate cell fate after genotoxic insult. Using HCT-116-isogenic-cell-lines, we evaluated the role of p53/p21 after 8-Cl-Ado-mediated response. Following 30 µM 8-Cl-Ado treatment, RNA synthesis was inhibited, p53 protein was stabilized, and p21 expression was activated. None of the cell types were arrested in G1/S phase, however, cells lacking p53 were blocked in G2/M. These cells had the least increase in apoptotic cells, although clonogenic survival demonstrated equal inhibition in all 4 cell types. Collectively, irrespective of p53 and p21 status, 8-Cl-Ado-induced cytotoxicity was similar.

Asunto(s)

RESUMEN

Human lung cancer H1299 (p53-null) cells often display enhanced susceptibility to chemotherapeutics comparing to A549 (p53-wt) cells. However, little is known regarding to the association of DNA damage-response (DDR) pathway heterogeneity with drug sensitivity in these two cells. We investigated the DDR pathway differences between A549 and H1299 cells exposed to 8-chloro-adenosine (8-Cl-Ado), a potential anticancer drug that can induce DNA double-strand breaks (DSBs), and found that the hypersensitivity of H1299 cells to 8-Cl-Ado is associated with its DSB overaccumulation. The major causes of excessive DSBs in H1299 cells are as follows: First, defect of p53-p21 signal and phosphorylation of SMC1 increase S phase cells, where replication of DNA containing single-strand DNA break (SSB) produces more DSBs in H1299 cells. Second, p53 defect and no available induction of DNA repair protein p53R2 impair DNA repair activity in H1299 cells more severely than A549 cells. Third, cleavage of PARP-1 inhibits topoisomerase I and/or topoisomerase I-like activity of PARP-1, aggravates DNA DSBs and DNA repair mechanism impairment in H1299 cells. Together, DDR pathway heterogeneity of cancer cells is linked to cancer susceptibility to DNA damage-based chemotherapeutics, which may provide aid in design of chemotherapy strategy to improve treatment outcomes.

Asunto(s)

RESUMEN

8-chloro-adenosine (8-Cl-Ado) is currently in phase-I clinical trials for acute myeloid leukaemia and chronic lymphocytic leukaemia (CLL). Previously, we demonstrated that treatment with 8-Cl-Ado leads to diminished ATP levels. We hypothesized that AMP-activated protein kinase (AMPK) signalling would be initiated in these cells, leading to induction of autophagy. AMPK activation and induction of autophagy were demonstrated during preclinical incubations in CLL cells with the analogues. Importantly, we extended similar observations in CLL lymphocytes during an 8-Cl-Ado phase-I trial. In conclusion, 8-Cl-Ado treatment induces autophagy in CLL lymphocytes in vitro as well as in vivo during clinical trial.

Asunto(s)

RESUMEN

Objective To investigate the response of multiple myeloma (MM) cells to 8-chloroadenosine 3',5'-monophosphate (8-Cl-cAMP) and the impact of arsenic trioxide (As2O3) on the above reaction.Methods MM-derived cell lines RPMI8226 and U266 were used as in vitro models.Cell apoptosis was evaluated according to cellular morphology and DNA content measured by flow cytometry.Meanwhile,rhodamine 123 (Rh123) staining and flow cytometry assay were used to detect the changes of mitochondrial transmembrane potentials (△ψm) in MM cells before and after the treatment.The synergic effects of 8-Cl-cAMP and As2O3 were evaluated by King' s formula.Results The 8-Cl-cAMP could induce growth inhibition of RPMI8226 and U266 cells in dose and time-related manners.The 8-Cl-cAMP could trigger apoptosis and △ψm collapse in MM cells through cellular morphology and flow cytometry analysis.As2O3 accelerated 8-Cl-cAMP-mediated apoptosis of RPMI8226 cells,but there were few synergic effects observed.Conclusion 8-Cl-cAMP could induce cell proliferation inhibition and apoptosis in MM cells.Mitochondria may be one of targets in 8-Cl-cAMP-mediated apoptosis.Furthermore,As2O3 catalyzes 8-Cl-cAMP-induced apoptosis.