P-glycoprotein expression is induced in human pancreatic cancer xenografts during treatment with a cell cycle regulator, mimosine

L‑mimosine induces caspase‑9‑mediated apoptosis in human osteosarcoma cells

L-mimosine is a rare plant amino acid extracted from Mimosa or Leucaena spp., and it has been reported to exhibit antitumor activity in a number of types of cancer. However, the underlying mechanisms remain to be clarified. In the present study, the effect of L‑mimosine was investigated in human osteosarcoma cells. A Cell Counting Kit‑8 assay and flow cytometry were used for toxicity detection. Hoechst staining and transmission electron microscopy (TEM), in addition to western blot analysis, were used for the examination of the associated mechanisms. The results of the present study indicated that L‑mimosine significantly inhibited cell proliferation by inducing cellular apoptosis in osteosarcoma cells. The Hoechst staining results and TEM revealed that nuclear damage increased with the concentration increase in L‑mimosine, as did the formation of apoptotic bodies. Additionally, the results of the western blot analysis confirmed that the treatment of cells with L‑mimosine was accompanied by increasing expression of cleaved caspase‑9. L‑mimosine‑induced apoptosis was inhibited by the caspase‑9 inhibitor Z‑LEHD‑FMK. In addition, the extracellular signal‑regulated kinase (ERK) signaling pathway was suppressed following treatment with L‑mimosine. In conclusion, the results of the present study suggested that L‑mimosine induced apoptosis via the mitochondrial apoptotic pathway. The ERK signaling pathway was indicated to be an additional mechanism underlying apoptosis induction. The results provided evidence for the use of L‑mimosine as a promising candidate for osteosarcoma therapy.

The Chemistry and Biological Activities of Mimosine: A Review

Mimosine [β-[N-(3-hydroxy-4-oxypyridyl)]-α-aminopropionic acid] is a non-protein amino acid found in the members of Mimosoideae family. There are a considerable number of reports available on the chemistry, methods for estimation, biosynthesis, regulation, and degradation of this secondary metabolite. On the other hand, over the past years of active research, mimosine has been found to have various biological activities such as anti-cancer, antiinflammation, anti-fibrosis, anti-influenza, anti-virus, herbicidal and insecticidal activities, and others. Mimosine is a leading compound of interest for use in the development of RAC/CDC42-activated kinase 1 (PAK1)-specific inhibitors for the treatment of various diseases/disorders, because PAK1 is not essential for the growth of normal cells. Interestingly, the new roles of mimosine in malignant glioma treatment, regenerative dentistry, and phytoremediation are being emerged. These identified properties indicate an exciting future for this amino acid. The present review is focused on the chemistry and recognized biological activities of mimosine in an attempt to draw a link between these two characteristics. Copyright © 2016 John Wiley & Sons, Ltd.

Phytochelators Intended for Clinical Use in Iron Overload, Other Diseases of Iron Imbalance and Free Radical Pathology

Iron chelating drugs are primarily and widely used in the treatment of transfusional iron overload in thalassaemia and similar conditions. Recent in vivo and clinical studies have also shown that chelators, and in particular deferiprone, can be used effectively in many conditions involving free radical damage and pathology including neurodegenerative, renal, hepatic, cardiac conditions and cancer. Many classes of phytochelators (Greek: phyto (φυτό)—plant, chele (χηλή)—claw of the crab) with differing chelating properties, including plant polyphenols resembling chelating drugs, can be developed for clinical use. The phytochelators mimosine and tropolone have been identified to be orally active and effective in animal models for the treatment of iron overload and maltol for the treatment of iron deficiency anaemia. Many critical parameters are required for the development of phytochelators for clinical use including the characterization of the therapeutic targets, ADMET, identification of the therapeutic index and risk/benefit assessment by comparison to existing therapies. Phytochelators can be developed and used as main, alternative or adjuvant therapies including combination therapies with synthetic chelators for synergistic and or complimentary therapeutic effects. The development of phytochelators is a challenging area for the introduction of new pharmaceuticals which can be used in many diseases and also in ageing. The commercial and other considerations for such development have great advantages in comparison to synthetic drugs and could also benefit millions of patients in developing countries.

Regulation of expression of deoxyhypusine hydroxylase (DOHH), the enzyme that catalyzes the activation of eIF5A, by miR-331-3p and miR-642-5p in prostate cancer cells

The enzyme deoxyhypusine hydroxylase (DOHH) catalyzes the activation of eukaryotic translation initiation factor (eIF5A), a protein essential for cell growth. Using bioinformatic predictions and reporter gene assays, we have identified a 182-nt element within the DOHH 3'-untranslated region (3'-UTR) that contains a number of target sites for miR-331-3p and miR-642-5p. Quantitative RT-PCR studies demonstrated overexpression of DOHH mRNA and underexpression of miR-331-3p and miR-642-5p in several prostate cancer cell lines compared with normal prostate epithelial cells. Transient overexpression of miR-331-3p and/or miR-642-5p in DU145 prostate cancer cells reduced DOHH mRNA and protein expression and inhibited cell proliferation. We observed synergistic growth inhibition with the combination of miR-331-3p and miR-642-5p and mimosine, a pharmacological DOHH inhibitor. Finally, we identified a significant inverse relationship between the expression of miR-331-3p or miR-642-5p and DOHH in a cohort of human prostate cancer tissues. Our results suggest a novel role for miR-331-3p and miR-642-5p in the control of prostate cancer cell growth via the regulation of DOHH expression and eIF5A activity.