The effect of microdosimetric 12C6+ heavy ion irradiation and Mg2+ on canthaxanthin production in a novel strain of Dietzia natronolimnaea.

BACKGROUND: Dietzia natronolimnaea is one of the most important bacterial bioresources for high efficiency canthaxanthin production. It produces the robust and stable pigment canthaxanthin, which is of special interest for the development of integrated biorefineries. Mutagenesis employing 12C6+ irradiation is a novel technique commonly used to improve microorganism productivity. This study presents a promising route to obtaining the highest feasible levels of biomass dry weight (BDW), and total canthaxanthin by using a microdosimetric model of 12C6+ irradiation mutation in combination with the optimization of nutrient medium components. RESULTS: This work characterized the rate of both lethal and non-lethal dose mutations for 12C6+ irradiation and the microdosimetric kinetic model using the model organism, D. natronolimnaea svgcc1.2736. Irradiation with 12C6+ ions resulted in enhanced production of canthaxanthin, and is therefore an effective method for strain improvement of D. natronolimnaea svgcc1.2736. Based on these results an optimal dose of 0.5-4.5 Gy, Linear energy transfer (LET) of 80 keV µm-1and energy of 60 MeV u-1 for 12C6+ irradiation are ideal for optimum and specific production of canthaxanthin in the bacterium. Second-order empirical calculations displaying high R-squared (0.996) values between the responses and independent variables were derived from validation experiments using response surface methodology. The highest canthaxanthin yield (8.14 mg) was obtained with an optimized growth medium containing 21.5 g L-1 D-glucose, 23.5 g L-1 mannose and 25 ppm Mg2+ in 1 L with an irradiation dose of 4.5 Gy. CONCLUSIONS: The microdosimetric 12C6+ irradiation model was an effective mutagenic technique for the strain improvement of D. natronolimnaea svgcc1.2736 specifically for enhanced canthaxanthin production. At the very least, random mutagenesis methods using 12C6+ions can be used as a first step in a combined approach with long-term continuous fermentation processes. Central composite design-response surface methodologies (CCD-RSM) were carried out to optimize the conditions for canthaxanthin yield. It was discovered D-glucose, Mg2+ and mannose have significant influence on canthaxanthin biosynthesis and growth of the mutant strain.

Decreased macrophage migration inhibitor factor expression up-regulats p27 in hepatocellular carcinoma / 中华肝脏病杂志

<p><b>OBJECTIVES</b>To observe the expression of macrophage migration inhibition factor (MIF) and p27 in hepatocellular carcinoma tissue, and to investigate the effect of MIF on the expression of p27 in hepatocellular carcinoma (HCC) cells.</p><p><b>METHODS</b>Immunohistochemistry and quantitative RT-PCR were performed to detect the expression of MIF and p27 in HCC tissues and peri-tumor tissues. Specific small interfering RNA (siRNA) targeting MIF gene was chemically synthesized and then transfected at the concentration of 50 nmol/L and 100 nmol/L into PLC cells and Hep3B cells. The mRNA levels of MIF and p27 after MIF siRNA treatment were quantified by real-time RT-PCR.</p><p><b>RESULTS</b>MIF protein and mRNA were over-expressed in the HCC tumor tissues compared to these in the peri-tumor tissues (P less than 0.01). The expression of p27 protein and mRNA was significantly lower in the HCC tumor tissues compared to these in the peri-tumor tissues (P less than 0.01). Compared to normal liver cell line L-02, HCC cell lines expressed higher level of MIF (F=61.036, P less than 0.01) and lower level of p27 (F=529.853, P less than 0.01). In MIF siRNA treated PLC and Hep3B cells, the MIF mRNA was decreased in a dose-dependent manner (F=320.1, P less than 0.01; F=201.2, P less than 0.01). The p27 mRNA was significantly up-regulated in MIF siRNA treated PLC and Hep3B cells compared to control siRNA transfected cells (F=419.4, P less than 0.01; F=459.9, P less than 0.01).</p><p><b>CONCLUSIONS</b>MIF is over-expressed in HCC tumor tissues, and the expression of p27 is repressed by MIF.</p>

Interference of osteopontin expression inhibits the invasion and metastasis of human hepatocellular carcinoma cell lines / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the effect of osteopontin (OPN) on the invasion and metastasis of human hapatocellular carcinoma (HCC).</p><p><b>METHODS</b>HCC cell lines (HCC-LM3) were transfected with the chemically synthesized small interfering RNA (siRNA). Real-time PCR and Western blot were used to quantify the mRNA and OPN protein levels. The malignant phenotypes including cellular growth, colony formation and invasion capability of the HCC cells were analyzed.</p><p><b>RESULTS</b>The OPN mRNA and proteins levels were decreased by 75% and 80% in OPN siRNA treated cells. Colony formation and migratory capability were reduced in OPN siRNA treated cells (P < 0.05).</p><p><b>CONCLUSION</b>The specific siRNA is able to reduce the OPN expression at both the mRNA and protein levels and significantly inhibits the invasiveness of HCC cells.</p>

Correlations of expressions of macrophage migration inhibitor factor and cyclin D1 with tumor size and metastasis of hepatocellular carcinoma / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To explore the possible relationship between the expressions of macrophage migration inhibitor factor (MIF), cyclin D1, cyclin-dependent kinase 4 (CDK4), phosphorylated-retinoblastoma susceptibility gene product Rb protein (phospho-Rb) and the development of hepatocellular carcinoma (HCC).</p><p><b>METHODS</b>93 HCC tissues and 5 normal liver tissues were used to investigate the expressions of MIF, cyclin D1, CDK4 and phospho-Rb by tissue microarray and immunohistochemistry methods.</p><p><b>RESULTS</b>The expression rates of MIF, cyclin D1, CDK4 and phospho-Rb in the HCC tissues were 71%, 41%, 82% and 14% respectively, and in the normal liver tissues, they were 0%, 0%, 80% and 20% respectively. The expression rates of MIF and cyclin D1 were significantly different between the tumor and the normal liver tissues and the expression rates of CDK4 and phospho-Rb were not significantly different between the tumor and the normal liver tissues. The rate difference (69% versus 48%) of MIF expression between the larger tumors (> 3.5 cm) and the smaller tumors (< 3.5 cm) was of statistical significance (P < 0.01). The expression rate (62%) of cyclin D1 in the tumors with metastasis was significantly higher than the expression rate (35%) in the tumors without metastasis (P < 0.05). MIF expression was positively correlated with cyclin D1 expression in the tumor tissues (P < 0.01). CDK4 and phospho-Rb expressions were not significantly associated with the tumor sizes and metastasis status.</p><p><b>CONCLUSION</b>Our results indicate that MIF and cyclin D1 might be related to the growth and metastasis of HCC.</p>