Experimental Study on the Mechanism of Mangiferin Inhibiting Malignant Biological Characteristics of Multiple Myeloma and Exerting Anticancer Effect / 中国实验血液学杂志

OBJECTIVE@#To investigate the effect of pure Chinese herbal extract Mangiferin on the malignant biological behaviors of multiple myeloma (MM) cells, and to analyze the molecular mechanism of the anti-myeloma effect of Mangiferin, so as to provide experimental basis for MM replacement therapy.@*METHODS@#U266 and RPMI8226 of human MM cell lines were intervened with different concentrations of Mangiferin. Cell proliferation was detected by CCK-8 method. Annexin V/PI double staining flow cytometry was used to detect cell apoptosis. Western blot was used to detect the expression of apoptosis and related signaling pathway proteins, and real-time quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression of matrix metalloproteinase (MMP) and CXC chemokine receptor (CXCR) family.@*RESULTS@#Mangiferin could inhibit the proliferation activity of U266 and RPMI8226 cells and induce cells apoptosis. After Mangiferin intervened in U266, RPMI8226 cells for 48 h, the expression of Bcl-2 family pro-apoptotic protein Bax was up-regulated, while the expression of survivin and Bcl-xL proteins was down-regulated and caspase-3 was hydrolyzed and activated to promote cell apoptosis, besides, the expression of Bcl-2 protein in U266 cells was also significantly down-regulated to induce apoptosis (P<0.05). After Mangiferin intervenes in MM cells, it can not only increase the expression level of tumor suppressor p53, but also induce programmed cell death of MM cells by inhibiting the expression of anti-apoptotic molecules and down-regulating the phosphorylation levels of AKT and NF-κB. In addition, after the intervention of Mangiferin, the expressions of CXCR4, MMP2 and MMP9 in U266 cells were down-regulated (P<0.05), while there is no effect on the expressions of CXCR2, CXCR7 and MMP13 (P>0.05). However, the expressions of CXCR4, MMP9, and MMP13 in RPMI8226 cells were down-regulated (P<0.01), the expression of MMP2 was weakly affected, and the expression of CXCR2 and CXCR7 was basically not affected (P>0.05).@*CONCLUSION@#Mangiferin can inhibit the proliferation and induce apoptosis of MM cells, and its mechanism may be related to inhibiting the activation of NF-κB signaling pathway, affecting the expression of Bcl-2 family proteins, and inhibiting the expression of core members of MMP and CXCR family.

The Effects and Regulatory Mechanism of Targeting CXC Chemokine Receptor 1/2 Combined with Ara-C on the Malignant Biological Behaviors of U937 Cells of Acute Myeloid Leukemia / 中国实验血液学杂志

OBJECTIVE@#To investigate and analyze the effect of CXC chemokine receptor 1/2 (CXCR1/2) targeting inhibitor Reparixin combined with cytarabine (Ara-C) on the malignant biological behaviors of acute myeloid leukemia cells and its effect on the expression of the CXCR family, while exploring the accompanying molecular mechanism, providing scientific basis and reference for new molecular markers and targeted therapy for AML.@*METHODS@#Acute myeloid leukemia U937 cells were treated with different concentrations of Reparixin, Ara-C alone or in combination, and the cell morphology was observed under an inverted microscope; Wright-Giemsa staining was used to detect cell morphological changes; CCK-8 method was used to detect cell proliferation; the ability of cell invasion was detected by Transwell chamber method; the ability of colony formation was detected by colony formation assay; cell apoptosis was detected by Hoechst 33258 fluorescent staining and Annexin V/PI double-staining flow cytometry; monodansylcadaverine(MDC) staining was used to detect cell autophagy; the expression of apoptosis, autophagy and related signaling pathway proteins was detected by Western blot and the expression changes of CXCR family were detected by real-time quantitative polymerase chain reaction (qRT-PCR).@*RESULTS@#Reparixin could inhibit the proliferation, invasion, migration and clone formation ability of U937 cells. Compared with the single drug group, when U937 cells were intervened by Reparixin combined with Ara-C, the malignant biological behaviors such as proliferation, invasion and colony formation were significantly decreased, and the levels of apoptosis and autophagy were significantly increased (P<0.01). After Reparixin combined with Ara-C intervenes in U937 cells, it can up-regulate the expression of the pro-apoptotic protein Bax and significantly down-regulate the expression of the anti-apoptotic protein Bcl-2, and also hydrolyze and activate Caspase-3, thereby inducing cell apoptosis. Reparixin combined with Ara-C could up-regulate the expressions of LC3Ⅱ and Beclin-1 proteins in U937 cells, and the ratio of LC3Ⅱ/LC3Ⅰ in cells was significantly up-regulated compared with single drug or control group (P<0.01). MDC result showed that the green granules of vesicles increased significantly, and a large number of broken cells were seen (P<0.01). Reparixin combined with Ara-C can significantly inhibit the phosphorylation level of PI3K, AKT and NF-κB signaling molecule, inhibit the malignant biological behavior of cells by inhibiting the activation of PI3K/AKT/NF-κB pathway, and induce programmed cell death. Ara-C intervention in U937 cells had no effect on the expression of CXCR family (P>0.05). The expression of CXCR1, CXCR2, and CXCR4 mRNA could be down-regulated by Reparixin single-agent intervention in U937 cells (P<0.05), and the expression of CXCR2 was more significantly down-regulated than the control group and other CXCRs (P<0.01). When Reparixin and Ara-C intervened in combination, the down-regulated levels of CXCR1 and CXCR2 were more significant than those in the single-drug group (P<0.01), while the relative expressions of CXCR4 and CXCR7 mRNA had no significant difference compared with the single-drug group (P>0.05).@*CONCLUSION@#Reparixin combined with Ara-C can synergistically inhibit the malignant biological behaviors of U937 cells such as proliferation, invasion, migration and clone formation, and induce autophagy and apoptosis. The mechanism may be related to affecting the proteins expression of Bcl-2 family and down-regulating the proteins expression of CXCR family, while inhibiting the PI3K/AKT/NF-κB signaling pathway.

Poly(ADP-ribosyl)ation of Apoptosis Antagonizing Transcription Factor Involved in Hydroquinone-Induced DNA Damage Response / 生物医学与环境科学（英文）

The molecular mechanism of DNA damage induced by hydroquinone (HQ) remains unclear. Poly(ADP-ribose) polymerase-1 (PARP-1) usually works as a DNA damage sensor, and hence, it is possible that PARP-1 is involved in the DNA damage response induced by HQ. In TK6 cells treated with HQ, PARP activity as well as the expression of apoptosis antagonizing transcription factor (AATF), PARP-1, and phosphorylated H2AX (γ-H2AX) were maximum at 0.5 h, 6 h, 3 h, and 3 h, respectively. To explore the detailed mechanisms underlying the prompt DNA repair reaction, the above indicators were investigated in PARP-1-silenced cells. PARP activity and expression of AATF and PARP-1 decreased to 36%, 32%, and 33%, respectively, in the cells; however, γ-H2AX expression increased to 265%. Co-immunoprecipitation (co-IP) assays were employed to determine whether PARP-1 and AATF formed protein complexes. The interaction between these proteins together with the results from IP assays and confocal microscopy indicated that poly(ADP-ribosyl)ation (PARylation) regulated AATF expression. In conclusion, PARP-1 was involved in the DNA damage repair induced by HQ via increasing the accumulation of AATF through PARylation.

A cell-based detection of ciguatoxin using sodium fluorescence probe / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a cell-based detection method of ciguatoxin using fluorescence assay.</p><p><b>METHODS</b>Mouse neuroblastoma N-2A cells were exposed to ouabain and veratridine and different concentrations of standard ciguatoxin samples (P-CTX-1) to establish the curvilinear relationship between the toxin dosage and fluorescence intensity using the sodium fluorescence probe CoroNaTM Green. The toxicity curvilinear relationship was also generated between the toxin dosage and cell survival using CCK-8 method. Based on these standard curves, the presence of ciguatoxin was detected in 33 samples of deep-sea coral fish.</p><p><b>RESULTS</b>A correlation was found between the detection results of cell-based fluorescence assay and cytotoxicity assay, whose detection limit reached 103 g/ml and 1012 g/ml, respectively. The cell-based fluorescent assay sensitivity showed a higher sensitivity than cytotoxicity assay with a 2-4 h reduction of the detection time.</p><p><b>CONCLUSIONS</b>The cell-based fluorescent assay can quickly and sensitively detect ciguatoxin and may serve as a good option for preliminary screening of the toxin.</p>

Possible role of DNA polymerase beta in protecting human bronchial epithelial cells against cytotoxicity of hydroquinone / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To explore the toxicological mechanism of hydroquinone in human bronchial epithelial cells and to investigate whether DNA polymerase beta is involved in protecting cells from damage caused by hydroquinone.</p><p><b>METHODS</b>DNA polymerase beta knock-down cell line was established via RNA interference as an experimental group. Normal human bronchial epithelial cells and cells transfected with the empty vector of pEGFP-C1 were used as controls. Cells were treated with different concentrations of hydroquinone (ranged from 10 micromol/L to 120 micromol/L) for 4 hours. MTT assay and Comet assay [single-cell gel electrophoresis (SCGE)] were performed respectively to detect the toxicity of hydroquinone.</p><p><b>RESULTS</b>MTT assay showed that DNA polymerase beta knock-down cells treated with different concentrations of hydroquinone had a lower absorbance value at 490 nm than the control cells in a dose-dependant manner. Comet assay revealed that different concentrations of hydroquinone caused more severe DNA damage in DNA polymerase beta knock-down cell line than in control cells and there was no significant difference in the two control groups.</p><p><b>CONCLUSIONS</b>Hydroquinone has significant toxicity to human bronchial epithelial cells and causes DNA damage. DNA polymerase beta knock-down cell line appears more sensitive to hydroquinone than the control cells. The results suggest that DNA polymerase beta is involved in protecting cells from damage caused by hydroquinone.</p>

hPARP1 genetic polymorphism in southern Chinese Han and Miao populations / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study hPARP1 genetic polymorphism in southern Chinese Han and Miao populations.</p><p><b>METHODS</b>Blood samples from 187 and 210 southern healthy Han and Miao populations were collected. The mutations of exons 12,13,16 and 17 of hPARP1 gene were investigated by PCR-single-strand conformation polymorphism(SSCP).</p><p><b>RESULTS</b>Fragments of 253 bp,313 bp,175 bp,362 bp within exons 12,13,16 and 17 respectively of hPARP1 gene were amplified by multiple PCR. An SSCP variant in exons 12,13,16 and 17 of PARP1 gene in 187 healthy Han and 210 healthy Miao individuals was identified. Seven single-base substitutions compared with the sequence of PARP1 gene were identified: a T to C transition in exon 12 (Phe548Ser), a G to T transition in exon 13 (Ala683Ser), a G to T transition in exon 16 (Asp798Tyr), and a A to G transition in exon 17 (His808Arg).</p><p><b>CONCLUSION</b>There were polymorphism sites in exons 12,13,16,17 of hPARP1 gene in southern Chinese Han and Miao populations; these results may be useful for the establishment of PARP1 genotyping, and these newly described PARP1 alleles would be advantageous indicators for population studies.</p>

Low concentration of hydroquinone-induced adaptive response in hPARP-1 protein normal and deficient cells / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate whether or not adaptive response of hPARP-1 protein normal and deficient cells is induced by low dose of hydroquinone (HQ), and to analyze the relationship between the adaptive response and micronuclei formation, and cell cycle alteration in human embryo lung fibroblasts (HLF), so as to elucidate the mechanism of adaptive response.</p><p><b>METHODS</b>HLF, HLFC and HLFP cells pretreated with low concentration were retreated by high concentration of HQ. Cellular viability, the rate of micronuclei and abnormal nuclei, cell cycle and DNA strand break were determined.</p><p><b>RESULTS</b>The tolerance to 80.0 micromol/L concentration of HQ was enhanced when HLF, HLFC and HLFP cells were pretreated with HQ from 0.001 - 0.050 micromol/L. There were varying degrees of micronuclei and abnormal nuclei in three cells pretreated with low concentration of HQ and then retreated with high concentration of HQ; the cell numbers of G1, G2, S phase in cell cycle were obviously different. When compared with only high attack dose, the micronuclei rate and abnormal nuclei rate of HLF, HLFC and HLFP decreased by pretreatment with HQ at high concentration (P < 0.05), meanwhile increased by pretreatment with HQ at low concentration (P < 0.05). HLF, HLFC and HLFP showed blockage in G2 phase when pretreated with HQ at 0 approximately 0.05 micromol/L, but HLFP showed blockage in G1 phase, and in S phase at 1.0 and 2.0 micromol/L.</p><p><b>CONCLUSION</b>The level of adaptive response of hPARP-1 protein deficient cells was lower than normal cell, suggesting that hPARP-1 protein may play an important role in the adaptive response of cells, which may be related with the regulation of cell cycle.</p>