BackgroundThe fundamental cause of overweight and obesity is consumption of calorie-dense foods. We have introduced a zero-calorie sweet sugar, d-psicose (d-allulose), a rare sugar that has been proven to have strong antihyperglycemic and antihyperlipidemic effects, and could be used as a replacement of natural sugar for the obese and diabetic subjects.AimAbove mentioned efficacy of d-psicose (d-allulose) has been confirmed in our previous studies on type 2 diabetes mellitus (T2DM) model Otsuka Long-Evans Tokushima Fatty (OLETF) rats with short-term treatment. In this study we investigated the long-term effect of d-psicose in preventing the commencement and progression of T2DM with the mechanism of preservation of pancreatic β-cells in OLETF rats.MethodsTreated OLETF rats were fed 5% d-psicose dissolved in water and control rats only water. Nondiabetic control rats, Long-Evans Tokushima Otsuka (LETO), were taken as healthy control and fed water. To follow the progression of diabetes, periodic measurements of blood glucose, plasma insulin, and body weight changes were continued till sacrifice at 60 weeks. Periodic in vivo body fat mass was measured. On sacrifice, pancreas, liver, and abdominal adipose tissues were collected for various staining tests.Resultsd-Psicose prevented the commencement and progression of T2DM till 60 weeks through the maintenance of blood glucose levels, decrease in body weight gain, and the control of postprandial hyperglycemia, with decreased levels of HbA1c in comparison to nontreated control rats. This improvement in glycemic control was accompanied by the maintenance of plasma insulin levels and the preservation of pancreatic β-cells with the significant reduction in inflammatory markers. Body fat accumulation was significantly lower in the treatment group, with decreased infiltration of macrophages in the abdominal adipose tissue.ConclusionOur findings suggest that the rare sugar d-psicose could be beneficial for the prevention and control of obesity and hyperglycemia with the preservation of β-cells in the progression of T2DM.

Glucose is a major energy source for mammalian cells and is transported into cells via cell-specific expression of various glucose transporters (GLUTs). Especially, cancer cells require massive amounts of glucose as an energy source for their dysregulated growth and thus over-express GLUTs. d-allose, a C-3 epimer of d-glucose, is one of rare sugars that exist in small quantities in nature. We have shown that d-allose induces the tumor suppressor gene coding for thioredoxin interacting protein (TXNIP) and inhibits cancer cell growth by G1 cell cycle arrest. It has also been reported that GLUTs including GLUT1 are overexpressed in many cancer cell lines, which may contribute to larger glucose utilization. Since d-allose suppresses the growth of cancer cells through the upregulation of TXNIP expression, our present study focused on whether d-allose down-regulates GLUT1 expression via TXNIP expression and thus suppresses cancer cell growth. Western blot and real-time PCR analyses revealed that d-allose significantly induced TXNIP expression and inhibited GLUT1 expression in a dose-dependent manner in three human cancer cell lines: hepatocellular carcinoma (HuH-7), Caucasian breast adenocarcinoma (MDA-MB-231), and neuroblastoma (SH-SY5Y). In these cell lines, d-allose treatment inhibited cell growth. Importantly, d-allose treatment decreased glucose uptake, as measured by the uptake of 2-deoxy d-glucose. Moreover, the reporter assays showed that d-allose decreased the expression of luciferase through the hypoxia response element present in the tested promoter region. These results suggest that d-allose may cause the inhibition of cancer growth by reducing both GLUT1 expression and glucose uptake.

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D‑allose is a rare sugar which has been shown to have growth inhibitory effects in several kinds of malignancies. However, the effect of D‑allose on lung cancer progression has not been previously studied. To investigate the antitumour effect of D‑allose in lung cancer cells and its mechanism, human non-small cell lung cancer (NSCLC) cell lines (squamous cell carcinomas: EBC1 and VMRC‑LCD; adenocarcinomas: A549, HI1017, RERF‑LC‑A1 and NCI-H1975) were treated with D‑allose (50 mM) with or without cisplatin (5 µM). D‑allose inhibited cell growth, particularly in EBC1 and VMRC‑LCD cells. In combination with cisplatin, D‑allose had a synergistic growth inhibitory effect. D‑allose increased the expression of thioredoxin interacting protein (TXNIP) at mRNA and protein levels. D‑allose decreased the proportion of cells in G1 phase and increased those in S and G2/M phases. For in vivo experiments, EBC1 cells were inoculated into BALB/c-nu mice. After tumourigenesis, D‑allose and cisplatin were injected. In this mouse xenograft model, additional treatment with D‑allose showed a significantly greater tumour inhibitory effect compared with cisplatin alone, accompanied by lower Ki‑67 and higher TXNIP expression. In conclusion, D‑allose inhibited NSCLC cell proliferation in vitro and tumour progression in vivo. In combination with cisplatin, D‑allose had an additional antitumour effect. Specifically, increased TXNIP expression and subsequent G2/M arrest play a role in D‑allose-mediated antitumour effects in NSCLC.

Although various parts of J. curcas (Jatropha curcas L., Euphorbiaceae) have long been used as traditional folk medicines for their antiviral, analgesic, and/or antidotal efficacies, we are the first to investigate the role of anti-carcinogenicity of isoamericanol A (IAA) from the seed extract. Our results showed that IAA is capable of inhibiting cell proliferation in a dose-dependent manner on the human cancer cell lines of MCF-7, MDA-MB231, HuH-7, and HeLa. Flow cytometry analysis showed IAA significantly induces cell cycle arrest at G2/M on MCF-7 cells. At both protein and mRNA levels examined by western blot and real-time PCR, the results revealed increased expression of BTG2 (B-cell translocation gene 2), p21 (p21WAF1/CIPI), and GADD45A (growth arrest and DNA-damage-inducible, alpha) after IAA treatment, but inversed expression in CDK1 (cyclin-dependent kinase 1) and cyclins B1 and B2. All these effects contribute to G2/M cell cycle arrest. Furthermore, these results coincide with the changes in molecular expressions determined by DNA-microarray analysis. Our findings indicate that IAA has an inhibitory effect on cell proliferation of MCF-7 through cell cycle arrest, giving it great potential as a future therapeutic reagent for cancers.

Thioredoxin interacting protein (TXNIP) is a novel tumor suppressor that is down‐regulated in several cancer tissues and tumor cell lines. Overexpression of TXNIP causes cell cycle arrest at the G1/S checkpoint in the hepatocellular carcinoma cell line HuH‐7. TXNIP contains putative phosphorylation sites, but the effects of its phosphorylation have not been fully characterized. TXNIP also contains two α‐arrestin domains (N‐arrestin and C‐arrestin) whose functions are not fully understood. Here, we reveal an association between TXNIP and cell cycle regulatory proteins (p27 kip1 , Jun activation domain‐binding protein 1 (JAB1), Cdk2, and cyclin E), suggesting its participation in cell cycle regulation. We observed phosphorylation of TXNIP and used both in vivo and in vitro kinase assays to demonstrate that TXNIP can be phosphorylated by p38 mitogen‐activated protein kinase. Furthermore, we also identified Ser361 in TXNIP as one of the major phosphorylation sites. Cell cycle analysis showed that Ser361 phosphorylation participates in TXNIP‐mediated cell cycle arrest. In addition, the C‐arrestin domain may also play an important role in cell cycle arrest. We also showed that phosphorylation at Ser361 may be important for the association of TXNIP with JAB1 and that the C‐arrestin domain is necessary for the nuclear localization of this molecule. Collectively, these studies reveal that TXNIP participates in cell cycle regulation through association with regulatory proteins, especially JAB1, and that C‐arrestin‐dependent nuclear localization is important for this function. This work may facilitate the development of a new cancer therapy strategy that targets TXNIP as a key molecule inhibiting cancer cell growth via cell cycle blockade at the G1/S checkpoint.

Jatropha seeds have gained popularity as a biodiesel fuel resource. The process of biodiesel production from the seeds, however, also creates a tremendous amount of defatted residue as a byproduct. In this study, the potential for pharmaceutical usage of extracts from the defatted residue of crushed Jatropha curcus L. seed was examined. Organic and water fractions of both ethyl acetate (EtOAc) and methanol (MeOH) extracts from the seed residue exhibited an inhibitory growth effect on the human cancer cell lines hepatocellular carcinoma (HuH-7) and breast cancer (MCF-7). Later, the effect of isoamericanol A from the MeOH-organic fraction was compared across three human cell lines in search of human cell types suitable for treatment (HuH-7, MCF-7, cervical cancer (HeLa)). Our results indicate that the effect of three-day isoamericanol A treatment differs by cell type. Although effective to some extent, HeLa cell growth was most inhibited at the smallest dosage, whereas MCF-7 growth suffered the greatest inhibition at the highest dosage. Our findings reveal possibility for utilization of the Jatropha seed residue extract as well as its active compound, isoamericanol A, as practical cancer treatments for certain cell types in the future.

CYP701B1 of the moss, Physcomitrella patents, might be a unique cytochrome P450 having the ent-kaurene oxidase (KO) activity occurring in nonvascular plant. Phylogenetic analysis suggested that the gene encoding CYP701B1 was diverged from a common ancestral gene encoding KO of vascular plants. CYP701B1 expressed in Phichia yeast microsomes was purified and characterized. The purified CYP701B1 catalyzed the oxidation of ent-kaurene to ent-kaurenoic acid through three successive monooxygenations, and the rate-limiting step of this oxidation might be the initial step that forms ent-kaurenol. CYP701B1 was a typical ferric low-spin cytochrome P450 and was completely moved to high-spin state upon binding with ent-kaurene, and apparent Kd of ent-kaurene estimated by the spectral change caused by this spin-state shift was 2.5 μM. The potent KO inhibitor uniconazole, an azole compound with molecular size similar to ent-kaurene, bound CYP701B1 with high affinity. However, ketoconazole, an azole compound whose molecular size is larger than ent-kaurene could not bind to CYP701B, though it binds strongly with CYP51, lanosterol 14-demethylase. The results indicated that the active site of CYP701B1 is fitted for the molecular size of ent-kaurene. The P450 monooxygenase adapted for ent-kaurene oxidation might appear in land plants before evolutionary divergence into vascular and nonvascular plants.