homoharringtonine and Multiple-Myeloma

The prognosis of patients with multiple myeloma who are resistant to proteasome inhibitors, immunomodulatory drugs (IMiD), and daratumumab is extremely poor. Even B-cell maturation antigen-specific chimeric antigen receptor T-cell therapies provide only a temporary benefit before patients succumb to their disease. In this article, we interrogate the unique sensitivity of multiple myeloma cells to the alternative strategy of blocking protein translation with omacetaxine.. We determined protein translation levels (. Overall, protein translation inhibitors represent a potential new drug class for myeloma treatment and provide a rationale for conducting clinical trials with omacetaxine alone and in combination with IMiDs for patients with relapsed/refractory multiple myeloma.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Bone Marrow; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Drug Synergism; Homoharringtonine; Humans; Immunomodulating Agents; Interferon Regulatory Factors; Mice; Multiple Myeloma; Primary Cell Culture; Protein Biosynthesis; Protein Synthesis Inhibitors; Proto-Oncogene Proteins c-myc; Signal Transduction; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Homoharringtonine (HHT) has been used as an antileukemia agent in the clinic which processes a high-potential therapeutic efficacy against multiple myeloma (MM). In this study, we investigated the antimyeloma mechanism of HHT.. Three MM cell lines and a xenograft model were applied. Mitochondrial function was evaluated by detecting MitoTracker Green, the mtDNA copy number, mitochondrial protein and enzyme activity, the mitochondrial membrane potential and mitochondrial morphology. Mitophagy levels were assessed by monitoring autophagosomes, performing a colocalization analysis and determining the levels of related proteins. An shRNA was applied to knockdown. Based on the results of the in vitro experiments, HHT exerted a promising antiproliferative effect on the MM.1S, RPMI 8226 and H929 cell lines by increasing mitophagy. In addition, HHT markedly inhibited myeloma tumor growth and prolonged survival by promoting mitophagy in vivo. Furthermore, HHT treatment contributed to notable mitochondrial dysfunction and Parkin-dependent mitophagy, as evidenced by the destruction of mitochondria, the decrease in the mtDNA copy number, decrease in the Bcl-2/Bax ratio, and decrease in the levels of mitochondrial proteins and the optimal expression of Parkin and NDP52. However, the addition of rapamycin did not produce significant synergistic effect with HHT, indicating that HHT reached the threshold level to induce mitophagy. The colocalization analysis and assessment of mitochondrial function examination further confirmed that HHT triggered mitophagy and mitochondrial dysfunction. Moreover, the antiproliferative effect of HHT was reversed by an shRNA targeting. HHT exerts an antimyeloma effect by inducing excess mitophagy, providing new mechanistic insights into a therapeutic strategy for MM.

Topics: Animals; Antineoplastic Agents, Phytogenic; Cell Proliferation; Cell Survival; Cephalotaxus; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Homoharringtonine; Humans; Mice; Mice, SCID; Molecular Structure; Multiple Myeloma; Neoplasms, Experimental; Structure-Activity Relationship; Tumor Cells, Cultured; Ubiquitin-Protein Ligases

Homoharringtonine (HHT) is a known anti-leukemia drug that inhibits multiple myeloma (MM) cells both in vitro and in vivo. Our prior study demonstrated that the potency of HHT in MM cells was compromised significantly when myeloma cells were co-cultured with BM stromal cells. This study aimed to investigate whether PI3K/Akt inhibitor LY294002 could potentiate the antimyeloma activity of HHT against MM cells adhered to BM stromal cells and in vivo xenograft models. A co-culture system composed of MM cells and human stromal cells was employed to mimic MM cells in bone marrow niche. The inhibitory and pro-apoptotic effect of HHT and LY294002 was determined by CCK-8 assay or flow cytometry. Expression of PI3K/Akt signaling molecules and anti-apoptotic protein myeloid cell leukemia-1 (Mcl-1) was assessed by western blot analysis and/or reverse transcription real-time quantitative PCR (RT-qPCR). MM xenografts were used to evaluate antitumor effect of combined therapy with HHT and LY294002. Adhesion to BM stromal cells rendered MM cells resistant to HHT whereas silencing Mcl-1 partly reversed the resistance. LY294002 induced apoptosis in MM cells and potentiated the antimyeloma effects of HHT by inhibiting the PI3K/Akt signal pathway which was abnormally activated during adhesion. LY294002 also enhanced the antimyeloma effect of HHT in in vivo xenograft models. These findings suggest that activation of PI3K/Akt signal pathway was responsible for the resistance to HHT in MM cells adhered to stromal cells. LY294002 can potentiate the antimyeloma activity of HHT both in vitro and in vivo, which may represent a new clinical treatment in MM.

Topics: Adult; Aged; Animals; Antineoplastic Agents, Phytogenic; Cell Adhesion; Cell Line, Tumor; Cell Survival; Chromones; Coculture Techniques; Dose-Response Relationship, Drug; Drug Synergism; Enzyme Inhibitors; Female; Harringtonines; Homoharringtonine; Humans; Male; Mice; Mice, SCID; Middle Aged; Morpholines; Multiple Myeloma; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Stromal Cells; Xenograft Model Antitumor Assays

Despite the great progress in the treatment, multiple myeloma (MM) still remains incurable. Bortezomib (BTZ), a reversible inhibitor of the 26S proteasome, is very effective against MM but unable to eradicate the MM cells in bone marrow niche eventually causing the disease relapse. Homoharringtonine (HHT) is a known anti-leukemia drug that inhibits MM both in vitro and in vivo. This study aimed to investigate whether HHT could potentiate the anti-tumor activity of BTZ in MM cells cocultured with bone marrow stromal cells and in vivo xenograft models. We found that coculture of myeloma cells with a human stroma cell line significantly decreased the sensitivity of myeloma cells to BTZ treatment. HHT inhibited the proliferation of MM cells and potentiated the anti-myeloma effects of BTZ by inhibition of both canonical and noncanonical NF-κB pathways. HHT also enhanced the anti-myeloma effect of BTZ in vivo xenograft models. Taken together, our data suggest that HHT can enhance the anti-myeloma activity of BTZ both in vitro and in vivo, which may represent a new clinical treatment in MM.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Bone Marrow; Bortezomib; Cell Adhesion; Coculture Techniques; Drug Synergism; Harringtonines; Heterografts; Homoharringtonine; Humans; Mice; Mice, SCID; Multiple Myeloma; Stromal Cells

To clarify the effects and mechanisms of homoharringtonine (HHT) monomer therapy or combination therapy with arsenic trioxide (ATO) on human multiple myeloma (MM) cell line RPMI 8226 in in vitro researches.. Effects of HHT, ATO, and HHT combined ATO on the growth of MM cell line RPMI 8226 were detected using MTT assay. The morphological changes of cell apoptosis were detected by Hoechst staining. The early apoptosis rate was detected using flow cytometry. Expressions of Caspase-3, Caspase-9, poly-ADP-ribose polymerase (PARP), Bcl-2, Mcl-1, Bcl-xl, and AKT protein were detected by Western blot.. HHT and ATO inhibited the proliferation of RPM1 8226 cell line in a time- and dose-dependent manner (P < 0.05). Synergistic effects was shown in the combination group (Cl < 1). HHT and ATO induced the apoptosis of RPMI 8226 in a dose-dependent manner with typical morphological changes of apoptosis and higher early stage apoptosis rate. The enhancement in apoptotic induction was seen when two agents were combined. HHT activated expressions of Caspase-3 and PARP in a dose dependent manner at 24 h. HHT at 40 ng/mL and ATO at 8.5 micromol/L could significantly activate expressions of Caspase-3 and Caspase-9, and down-regulate expressions of anti-apoptotic proteins Bcl-xl and Mcl-1. In addition, the combination therapy of HHT at 40 ng/mL and ATO at 8.5 micromol/L inhibited phosphorylation of AKT in a time-dependent manner.. HTT, ATO, and combination therapy of HHT and ATO induced the apoptosis of RPMI 8226 cell line possibly through activating Caspase pathways, regulating expressions of Bcl-2 families, and inhibiting phosphorylation of AKT.

Topics: Apoptosis; Arsenic Trioxide; Arsenicals; bcl-X Protein; Caspase 3; Caspase 9; Cell Line, Tumor; Harringtonines; Homoharringtonine; Humans; Multiple Myeloma; Myeloid Cell Leukemia Sequence 1 Protein; Oxides; Phosphorylation; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2

Involvement of phosphatidylinositol 3-kinase/Akt-1 in cell survival and proliferation of multiple myeloma (MM) has been well established. In this study, we demonstrate that homoharringtonine (HHT), an antileukemic drug first isolated from the Chinese evergreen Cephalotaxus harringtonia, induces significant cytotoxicity in dexamethasone-sensitive and -resistant and chemotherapy-sensitive MM cell lines in a time and dose-dependent manner. HHT also triggers apoptosis in chemotherapy-resistant patient's myeloma cells. Contrary to dexamethasone, the cytotoxicity of HHT on myeloma is independent of interleukin-6. The mechanism of HHT cytotoxicity is related to down-regulation of Akt phosphorylation/activation and various target genes of Akt including nuclear factor kappa B, XIAP, cIAP and cyclin D1. Moreover, in vivo antitumor activity of HHT is demonstrated in RPMI8226 myeloma xenograft model. Importantly, an additive effect of antitumor is confirmed in the myeloma cells treated with HHT and bortezomib concomitantly with inhibition of phosphorylated Akt. Together, these findings obtained with HHT should give useful insights into a novel antimyeloma chemotherapy.

Topics: Animals; Apoptosis; Boronic Acids; Bortezomib; Down-Regulation; Drug Resistance, Neoplasm; Drug Synergism; Harringtonines; Homoharringtonine; Humans; Mice; Mice, SCID; Multiple Myeloma; Phosphorylation; Proto-Oncogene Proteins c-akt; Pyrazines; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Since a variety of cell intrinsic and extrinsic molecular abnormalities cooperatively promote tumor formation in multiple myeloma (MM), therapeutic approaches that concomitantly target more than one molecule are increasingly attractive. We herein demonstrate the anti-myeloma effect of a cephalotaxus alkaloid, homoharringtonine (HHT), an inhibitor of protein synthesis, through the induction of apoptosis. HHT significantly reduced Mcl-1, a crucial protein involved in myeloma cell survival, in all three myeloma cell lines examined, whereas certain BH3-only proteins, such as Bim, Bik, and Puma, remained unchanged following HHT treatment, and their expression levels depended on the cell type. HHT also reduced the levels of c-FLIP(L/S), activated caspase-8, and induced active truncated-Bid. Thus, HHT-induced apoptosis appears to be mediated via both intrinsic and extrinsic apoptosis pathways, and the resultant imbalance between BH3-only proteins and Mcl-1 may be pivotal for apoptosis by HHT. In addition, HHT treatment resulted in reduced levels of beta-catenin and XIAP proteins, which also contribute to disease progression and resistance to chemotherapy in MM. In combination, HHT enhanced the effects of melphalan, bortezomib, and ABT-737. These results suggest that HHT could constitute an attractive option for MM treatment though its ability to simultaneously target multiple tumor-promoting molecules.

Topics: Antineoplastic Agents; Apoptosis; beta Catenin; Cell Line, Tumor; Cell Survival; Drug Synergism; Gene Expression Regulation, Neoplastic; Harringtonines; Homoharringtonine; Humans; Multiple Myeloma; Myeloid Cell Leukemia Sequence 1 Protein; Protein Synthesis Inhibitors; Proto-Oncogene Proteins c-bcl-2; X-Linked Inhibitor of Apoptosis Protein

Homoharringtonine (HHT) is a plant alkaloid with antileukemic activity which is currently being used for treatment of acute and chronic leukemias. The present studies have evaluated the effect of HHT on proliferation and apoptosis in human myeloma cells. Myeloma cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyl tetrazolium bromide (MTT) assay. Apoptotic cells and cell cycle were evaluated by flow cytometry. Level of caspase-8, caspase-9, caspase-3, and DNA repair enzyme poly (ADP-ribose) polymerase (PARP), were investigated using Western blot analysis. We found that HHT significantly inhibited the proliferation of human multiple myeloma (MM) cell lines and tumor cells from patients with relapsed refractory MM in a dose-dependent manner. HHT also induced apoptosis in myeloma cells as evidenced by flow cytometric detection of annexin V binding assay. This apoptotic process was associated with the activation of caspase-8, caspase-9, caspase-3 and PARP. The results also demonstrate that HHT potentiates dexamethasone-induced killing of MM cells. These findings indicate that HHT may be effective in the treatment of MM.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Caspases; Cell Division; Cell Line, Tumor; Dexamethasone; Drug Synergism; Harringtonines; Homoharringtonine; Humans; Multiple Myeloma; Poly(ADP-ribose) Polymerases

Topics: Aged; Antineoplastic Agents, Phytogenic; Antineoplastic Combined Chemotherapy Protocols; Arsenic Trioxide; Arsenicals; Carmustine; Cyclophosphamide; Dexamethasone; Doxorubicin; Harringtonines; Homoharringtonine; Humans; Male; Melphalan; Multiple Myeloma; Oxides; Prednisone; Remission Induction; Salvage Therapy; Thalidomide; Vincristine; Vindesine