MSFTZ, a flavanone derivative, induces human hepatoma cell apoptosis via a reactive oxygen species- and caspase-dependent mitochondrial pathway

Hyperoside, a flavonoid compound, inhibits proliferation and stimulates osteogenic differentiation of human osteosarcoma cells

Osteosarcoma, one of the most common malignant bone tumours, is generally considered a differentiation disease caused by genetic and epigenetic disruptions in the terminal differentiation of osteoblasts. Novel therapies based on the non-cytotoxic induction of cell differentiation-responsive pathways could represent a significant advance in treating osteosarcoma; however, effective pharmaceuticals to induce differentiation are lacking. In the present study, we investigated the effect of hyperoside, a flavonoid compound, on the osteoblastic differentiation of U2OS and MG63 osteosarcoma cells in vitro. Our results demonstrated that hyperoside inhibits the proliferation of osteosarcoma cells by inducing G₀/G₁ arrest in the cell cycle, without causing obvious cell death. Cell migration assay further suggested that hyperoside could inhibit the invasion potential of osteosarcoma cells. Additionally, osteopontin and runt-related transcription factor 2 protein levels and osteocalcin activation were upregulated dramatically in hyperoside-treated osteosarcoma cells, suggesting that hyperoside may stimulates osteoblastic differentiation in osteosarcoma cells. This differentiation was accompanied by the activation of transforming growth factor (TGF)-β and bone morphogenetic protein-2, suggesting that the hyperoside-induced differentiation involves the TGF-β signalling pathway. To our knowledge, this study is the first to evaluate the differentiation effect of hyperoside in osteosarcoma cells and assess the possible potential for hyperoside treatment as a future therapeutic approach for osteosarcoma differentiation therapy.

Bortezomib sensitizes human acute myeloid leukemia cells to all-trans-retinoic acid-induced differentiation by modifying the RARα/STAT1 axis

All-trans-retinoic acid (ATRA) has held great promise for differentiation-based therapy but reportedly downregulates retinoic acid receptor-α (RARα) in a proteasome-dependent manner, which leads to decreased acute myeloid leukemia (AML) cell differentiation efficiency. Therefore, research strategies that seek to further sensitize cells to retinoids and extend the range of retinoid-affected myeloid malignancies beyond acute promyelocytic leukemia (APL) are key investigative avenues. Here, we show that bortezomib, the first proteasome inhibitor approved for newly diagnosed and relapsed multiple myeloma, exhibited strong synergism with ATRA to promote HL60 and NB4 AML cell differentiation. We observed that bortezomib sensitized AML cells to ATRA-induced morphologic, biochemical, and functional changes, indicative of myeloid differentiation without cell death. In addition, treatment of human leukemia HL60 xenografts with bortezomib and ATRA together did not increase bortezomib-induced progressive weight loss but resulted in significant tumor growth inhibition in addition to increased differentiation (P < 0.05). These enhanced differentiation effects were accompanied by RARα stabilization and STAT1 activation. Taken together, our study was the first to evaluate bortezomib and ATRA synergy in AML cell differentiation and to assess new opportunities for bortezomib and ATRA combination as a promising approach for future differentiation therapy.

Effects of 4',7-dimethoxyflavanone on cell cycle arrest and apoptosis in human breast cancer MCF-7 cells

The present study was designed to investigate the anticancer activity of 4,7-dimethoxyflavanone in vitro. When human breast cancer MCF-7 cells were treated with 4',7-dimethoxyflavanone at various concentrations (1-200 μM) for 24 h, antiproliferative effects were first observed at 1 μM and the IC(50) was 115.62 μM. Conversely, 4',7-dimethoxyflavanone was not cytotoxic (measured as lactate dehydrogenase release in CHO-K1 cells) under the same conditions. MCF-7 cells exposed to the 4',7-dimethoxyflavanone at the IC(50) concentration showed cell cycle arrest and apoptosis. Compared to the respective control level, exposure to 4',7-dimethoxyflavanone resulted in a remarkable increase of small DNA fragments at the sub-G1 phase and an increase in the G2/M phase cell population. Moreover, when 4',7-dimethoxyflavanone treatment caused G2/M phase arrest, an increase in CDK1 together with an increase in cyclin B was observed. Based on these results, 4',7-dimethoxyflavanone may be a useful anticancer agent.

Camptothecin-20(s)-O-[N-(3'α,12'α-dihydroxy-24'-carbonyl-5'β-cholan)]-lysine, a novel camptothecin analogue, induces apoptosis towards hepatocellular carcinoma SMMC-7721 cells

Camptothecin-20(s)-O-[N-(3’α,12’α-dihydroxy-24’-carbonyl-5’β-cholan)]-lysine (B2) is a novel camptothecin analogue. Our previous study had shown that it displayed higher cytoxicity activity towards hepatocellular carcinoma SMMC-7721 cells than camptothecin (CPT) in vitro. In this paper, the underlying mechanism of anti-proliferation of B2 towards SMMC-7721 cells was further examined. Cell growth inhibition of B2 was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay; morphological changes were observed under Laser Scanning Confocal Microscope (LSCM); cell cycle distribution, apoptotic population, changes in mitochondrial membrane potential, intracellular calcium concentration and reactive oxygen species (ROS) production were determined by flow cytometry (FCM). Activities of caspase-3 and caspase-9 were measured, and the expression level of Bcl-2 and Bax proteins were analyzed by Western blot. The results suggested that B2 inhibited SMMC-7721 cell growth by causing cell cycle arrest at the S and G2/M phases, and induced apoptosis involving a mitochondrial pathway. B2 appears to cause a high induction of apoptosis on SMMC-7721 cells in vitro, which suggests it might be a potential drug for cancer therapy.

The effect of N-acetylcysteine on the antitumor activity of ifosfamide

Ifosfamide-induced nephrotoxicity is a serious adverse effect in children undergoing chemotherapy. Our previous cell and rodent models have shown that the antioxidant N-acetylcysteine (NAC), used extensively as an antidote for acetaminophen poisoning, protects renal tubular cells from ifosfamide-induced nephrotoxicity at a clinically relevant concentration. For the use of NAC to be clinically relevant in preventing ifosfamide nephrotoxicity, we must ensure there is no effect of NAC on the antitumor activity of ifosfamide. Common pediatric tumors that are sensitive to ifosfamide, human neuroblastoma SK-N-BE(2) and rhabdomyosarcoma RD114-B cells, received either no pretreatment or pretreatment with 400 µmol/L of NAC, followed by concurrent treatment with NAC and either ifosfamide or the active agent ifosfamide mustard. Ifosfamide mustard significantly decreased the growth of both cancer cell lines in a dose-dependent manner (p < 0.001). The different combined treatments of NAC alone, sodium 2-mercaptoethanesulfonate alone, or NAC plus sodium 2-mercaptoethanesulfonate did not significantly interfere with the tumor cytotoxic effect of ifosfamide mustard. These observations suggest that NAC may improve the risk/benefit ratio of ifosfamide by decreasing ifosfamide-induced nephrotoxicity without interfering with its antitumor effect in cancer cells clinically treated with ifosfamide.

Efficient activation of p53 pathway in A549 cells exposed to L2, a novel compound targeting p53-MDM2 interaction

The tumor suppressor p53 plays a key role in the regulation of cell cycle, apoptosis, DNA repair, and senescence. It acts as a transcriptional factor, and is able to activate various genes to exert specific functions. MDM2, the main regulator of p53, inhibits the function of p53 through direct interaction. On the basis of this finding, inhibiting the MDM2-p53 interaction can be a potentially important target for cancer therapy. We showed here that L2, an analog of small-molecule MDM2 antagonist nutlins, stabilized p53 and selectively activated the p53 pathway in p53 wild-type A549 cells, resulting in a pronounced antiproliferation effect through inducing cell cycle arrest and apoptosis. Meanwhile, we confirmed by immunoprecipitation analysis that L2 could also inhibit MDM2-p53 interaction, similar to nutlin-1. Real-time PCR results revealed that L2 had no effect on the p53 gene transcriptional level, but it could induce the upregulation of p21 at the transcriptional level, which was the downstream of p53. Therefore, we concluded that the accumulation of p53 caused by L2 was mainly because of the decrease of the protein degradation rather than the elevation of p53 gene expression. Furthermore, no phosphor-p53 formed after L2 treatments, indicating that a genetoxic mechanism was unlikely to contribute to the activation of p53 by L2. In conclusion, the data acquired from A549 cells indicated that L2 exhibited high antiproliferation activity by disrupting MDM2-p53 interaction, and that the mechanism was derived from the activation of p53 and the p53 pathway. It was also surprising that L2 showed high antiproliferation effect against p53 null HL60 cells, which was quite different from nutlin-1. G2/M phase arrest might have contributed to the high antiproliferation activity of L2 on HL60 cells. The changes of p53 and MDM2 protein levels in L2-treated HL60 cells indicated that the mechanisms involved in the cell cycle arrest in A549 and HL60 cells were probably different, to which our future research would be devoted.

Antimetastatic activity of MONCPT in preclinical melanoma mice model

Previous study demonstrated that MONCPT, a topoisomerase I inhibitor, exhibited potent anti-proliferation and anti-angiogenesis activity in vitro and in vivo. In this study, we report the efficacy of MONCPT against the development of melanoma metastasis by an intravenous injection of green fluorescent protein-transfected mice melanoma carcinoma (B16F10-GFP) cells in C57BL/6 mice. MONCPT (2.0, 5.0 and 12.5 mg/kg/2 days) markedly decreased B16F10-GFP pulmonary metastases by 12.8%, 53.1% and 76.3%, respectively; whereas higher doses of MONCPT (31.0 mg/kg/2 days) significantly inhibited the tumor growth of B16F10 xenograft model. In the in vitro experiment, MONCPT suppressed the B16F10-GFP cell invasion and migration without affecting cell survival. Further studies demonstrated that MONCPT decreased the secretion of matrix metalloproteinase (MMP)-9 and VEGF, and reduced the protein expression of HIF-1α as well as the phosphorylation level of ERK in B16F10-GFP cells. These in vivo and in vitro results indicate that MONCPT possesses both the potent antimetastatic ability and the tumor growth-inhibition activity, and the dual function promises MONCPT as a potential therapeutic agent for tumor metastasis and tumor growth of melanoma carcinoma.

Reactive oxygen species production and Bax/Bcl-2 regulation in honokiol-induced apoptosis in human hepatocellular carcinoma SMMC-7721 cells

We investigated possible mechanism(s) where honokiol induces apoptosis in human hepatocellular carcinoma SMMC-7721 cells. MTT assay showed that honokiol has strong inhibition on SMMC-7721 cells in a dose-dependent manner. SMMC-7721 cells after honokiol treatment display morphological characteristics such as cell shrinkage, detachment from the culture plate, formation of apoptotic bodies, change to a round shape, and marked nuclear condensation and fragmentation after 32258 staining. Cell apoptosis was measured by Annexin-V/PI staining and alternatively, by the subG0/G1 percentage of the cell cycle analysis followed by FACS. An obvious loss of ΔΨ(m) and a quick burst of ROS was detected when honokiol reached 4μg/ml, which was coincident with the high apoptosis percentage in our previous research. Up-regulation of Bax and down-regulation of Bcl-2 were observed, suggesting that honokiol-induced apoptosis was associated with reactive oxygen species (ROS) production and an increase of Bax/Bcl-2 ratios.

The effect of delivery via narrow-bore needles on mesenchymal cells

AIMS

Recently, there have been numerous preclinical and human studies investigating the regenerative capacity of cell suspensions following their direct injection into a target organ: the fundamental parameters for successful (clinical) cell therapy. At present, limited data exist in the identification of factors important for the survival of these cells (i.e., morphology, viability and proliferation rates) during and following their ejection via narrow-bore needles.

MATERIALS & METHODS

Primary murine mesenchymal stem cells (mMSCs) were isolated, expanded and processed into a concentrated cell suspension consisting of either HBSS or HBSS supplemented with the antioxidant n-acetyl-cysteine. This suspension was then ejected from a 10 microl Hamilton syringe, via a variety of bore-sized needles, at different ejection rates. Cell characteristics including viability, spreading and attachment, apoptosis and proliferative ability were then assessed.

RESULTS

Following manipulation within a syringe, a decrease in the viability and cell spreading of mMSCs and a concurrent increase in the production of the caspase-3 protein, an early regulatory event in apoptosis, occurs. These detrimental effects were found to be increased when the cells were left in the syringe chamber for increased periods of time, and were similar at 5 microl/min and 1 microl/min ejection rates. However, on increasing the needle bore diameter, a significant reduction in these characteristics was observed. By comparison, mMSCs that were left to stand at room temperature (18-20 degrees C), but were not manipulated within a syringe, showed a significantly greater viability compared with manipulated cells. However, cells kept at 4 degrees C demonstrated a decreased viability compared with manipulated cells. When the mMSC were incubated with n-acetyl-cysteine, a known antioxidant, no significant change in caspase-3 production or cell spreading was observed.

CONCLUSIONS

This study highlights potential parameters, such as minimizing the time period the cells are within the syringe and the use of wider-bore needles, involved in maintaining the high viable cell density required for the delivery of cell suspensions for cell therapy applications.