Effects and mechanism of arsenic trioxide in combination with rmhTRAIL in multiple myeloma

Effects of Arsenic Trioxide on INF-gamma Gene Expression in MRL/lpr Mice and Human Lupus

Arsenic trioxide (As2O3; ATO), a traditional Chinese medicine, is used to treat patients with acute promye-locytic leukemia, while its application for treatment of systemic lupus erythematosus (SLE) is still under evaluation. The high expression of INF-gamma (INF-γ) is a primary pathogenic factor in SLE. It is found that ATO can reduce INF-γ expression levels in lupus-prone mice, whereas it is not clear whether ATO has the same effect on SLE patients. Therefore, this study was to investigate the underlying mechanism of the effects of ATO on the expression of INF-γ in splenocytes of MRL/lpr mice and PBMCs of human lupus. The mRNA and protein expression levels of INF-γ were assessed by real-time RT-PCR and ELISA, respectively. The histone acetylation status of the INF-γ promoter and the binding of RNA polymerase II (RNA Pol II) to the INF-γ promoter were detected using a chromatin immunoprecipitation (ChIP) technique. The mRNA and protein expression levels of INF-γ decreased in both splenocytes of MRL/lpr mice and PBMCs of SLE patients with ATO treatment, which were accompanied by reduced histone H4 and H3 acetylation in INF-γ promoter and decreased combination of RNA Pol II to the INF-γ promoter. Therefore, ATO may reduce the expression level of the INF-γ by altering the levels of INF-γ promoter acetylation and the combination of RNA Pol II to the INF-γ promoter in splenocytes of MRL/lpr mice and PBMCs of SLE patients.

Effects of Recombinant Circularly Permuted Tumor Necrosis Factor (TNF)-Related Apoptosis-Inducing Ligand (TRAIL) (Recombinant Mutant Human TRAIL) in Combination with 5-Fluorouracil in Human Colorectal Cancer Cell Lines HCT116 and SW480

Background

Circularly permuted tumor necrosis factor-related apoptosis-inducing ligand, a mutant form of tumor necrosis factor-related apoptosis-inducing ligand, is an effective antitumor cytokine. However, its antitumor effect in colorectal cancer is unclear. This study assessed the antitumor effect of circularly permuted tumor necrosis factor-related apoptosis-inducing ligand alone or with 5-fluorouracil in colorectal cancer cells in vitro and explored the underlying mechanisms.

Material/Methods

We used the (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay to analyze cell proliferation inhibition. The apoptotic effects of circularly permuted tumor necrosis factor-related apoptosis-inducing ligand, 5-fluorouracil, or both in human colorectal cancer cells were evaluated using flow cytometry. Furthermore, the levels of apoptosis-related proteins were examined by Western blotting.

Results

Compared to either agent alone, cotreatment with 5-fluorouracil and circularly permuted tumor necrosis factor-related apoptosis-inducing ligand showed obvious antitumor effects and induced significant apoptosis of colorectal cancer cells. 5-Fluorouracil enhanced circularly permuted tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis by increasing death receptor 4 and 5 levels in HCT116 cells, but only of death receptor 4 in SW480 cells. Moreover, 5-fluorouracil plus circularly permuted tumor necrosis factor-related apoptosis-inducing ligand increased apoptosis-related protein levels such as cleaved caspase-3, caspase-8, and poly-ADP-ribose polymerase and downregulated that of the survival protein B-cell lymphoma-extra-large. Pretreatment with the pan-caspase inhibitor, z-VAD-FMK, attenuated the caspase-dependent apoptosis induced by circularly permuted tumor necrosis factor-related apoptosis-inducing ligand alone or combined with 5-fluorouracil.

Conclusions

Cotreatment with 5-fluorouracil and circularly permuted tumor necrosis factor-related apoptosis-inducing ligand showed enhanced antitumor effects on colorectal cancer cells.

Realgar nanoparticles versus ATO arsenic compounds induce in vitro and in vivo activity against multiple myeloma

Multiple myeloma (MM), a B cell malignancy characterized by clonal proliferation of plasma cells in the bone marrow, remains incurable despite the use of novel and conventional therapies. In this study, we demonstrated MM cell cytotoxicity triggered by realgar (REA; As₄ S₄ ) nanoparticles (NREA) versus Arsenic trioxide (ATO) against MM cell lines and patient cells. Both NREA and ATO showed in vivo anti-MM activity, resulting in significantly decreased tumour burden. The anti-MM activity of NREA and ATO is associated with apoptosis, evidenced by DNA fragmentation, depletion of mitochondrial membrane potential, cleavage of caspases and anti-apoptotic proteins. NREA induced G₂ /M cell cycle arrest and modulation of cyclin B1, p53 (TP53), p21 (CDKN1A), Puma (BBC3) and Wee-1 (WEE1). Moreover, NREA induced modulation of key regulatory molecules in MM pathogenesis including JNK activation, c-Myc (MYC), BRD4, and histones. Importantly, NREA, but not ATO, significantly depleted the proportion and clonogenicity of the MM stem-like side population, even in the context of the bone marrow stromal cells. Finally, our study showed that both NREA and ATO triggered synergistic anti-MM activity when combined with lenalidomide or melphalan. Taken together, the anti-MM activity of NREA was more potent compared to ATO, providing the preclinical framework for clinical trials to improve patient outcome in MM.

Circularly permuted TRAIL plus thalidomide and dexamethasone versus thalidomide and dexamethasone for relapsed/refractory multiple myeloma: a phase 2 study

PURPOSE

Circularly permuted TRAIL (CPT) has exhibited promising efficacy as a mono-therapy or in combination with thalidomide for patients with multiple myeloma (MM). In this phase 2 study, the safety and efficacy of CPT in combination with thalidomide and dexamethasone (CPT + TD) was evaluated in patients with pretreated relapsed/refractory MM (RRMM).

METHODS

Patients who received at least two previous therapies for MM were randomly assigned at a 2:1 ratio to receive treatment with CPT + TD or thalidomide and dexamethasone (TD). The primary endpoint was the overall response rate (ORR), and the secondary endpoints included progression-free survival (PFS), duration of response (DOR) and safety.

RESULTS

Overall, 47 patients were assigned to the CPT + TD group, and 24 patients were recruited to the TD group. The ORR in the CPT + TD group was 38.3 vs. 25.0% in the TD group. The median PFS time was 6.7 months for the CPT + TD group and 3.1 months for the TD group. The median DORs for the CPT + TD and TD groups were 7.1 and 3.2 months, respectively. Most of the adverse effects (AEs) were grade 1 or 2. Serious AEs were reported in 19.7% of the patients. No treatment-related deaths were reported.

CONCLUSION

CPT plus TD could serve as a new therapeutic strategy for patients with RRMM. A randomized, double-blind, placebo-controlled confirmatory study is currently under way.