Yongri Zheng

Downregulation of miR-221/222 sensitizes glioma cells to temozolomide by regulating apoptosis independently of p53 status

A previous study showed that miR-221/222 can regulate cell apoptosis. p53 is a well known tumor suppressor which can influence the chemosensitivity of glioma cells. However, the effect of miR-221/222 in gliomas with different p53 status is unknown. Here, we demostrate that knockdown of miR-221/222 increases apoptosis in human gliomas of different p53 types (U251 cells, p53 mutant-type; LN308 cells, p53 null-type; and U87 cells, p53 wild-type). Furthermore, the effect of miR-221/22 caused no change of p53 expression in the glioma cells studied. In addition, when a specific siRNA against p53 was employed in U87 cells, no attenuation of apoptosis was found after knockdown of miR-221/222. Importantly, we found that As-miR-221/222-treated cells increased expression of Bax, cytochrome c, Apaf-1 and cleaved-caspase-3. Our results showed that low expression of miR-221/222 sensitized glioma cells to temozolomide (TMZ); in addition, ectopic expression of PUMA by pcDNA-PUMA had a similar effect. Taken together, our study indicates that downregulated miR-221/222 can sensitize glioma cells to TMZ by regulating apoptosis independently of p53 status.

Expression and function of miR-27b in human glioma.

Our previous miRNAs profiling study showed that miR-27b was up-regulated in glioma cells compared with H4 low grade astrocytoma cells. However, the main function of miR-27b in glioma in not known yet. The aim of this study was to investigate the expression and function of miR-27b in the pathogenesis of glioma. Real-time PCR showed that miR-27b was up-regulated in glioma samples and glioma cells. Down-regulation of miR-27b triggered growth inhibition, induced apoptosis and inhibited invasion in glioma cells. Furthermore, TOPflash luciferase activity was decreased significantly, while FOPflash luciferase did not change significantly. In addition, Western blot assay showed that STAT3, c-myc and cyclin D1 were knocked down after treatment with miR-27b inhibitor. These findings suggest that aberrantly up-regulated miR-27b may be one of the critical factors that contribute to malignancy in human gliomas.

LY294002 enhances cytotoxicity of temozolomide in glioma by down-regulation of the PI3K/Akt pathway

The introduction of temozolomide (TMZ) has advanced chemotherapy for malignant gliomas. However, a considerable number of glioblastoma (GBM) cases are refractory to TMZ. Previous studies have revealed that the PI3K/Akt pathway is activated in an ataxia telangiectasia and Rad3 related-dependent manner in response to TMZ. Thus, we hypothesized that PI3K inhibitors may act as antitumor agents against gliomas and potentiate the cytotoxicity of TMZ. The cytotoxicity of a PI3K inhibitor, LY294002, was examined both alone and in combination with TMZ in human glioma cell lines. Proliferation of tumor cells treated with LY294002 in combination with TMZ was significantly suppressed compared to treatment with either drug used alone. The combination treatment induced a higher apoptosis rate, while reducing the invasive capability of U87 cells. The apoptosis-associated proteins, cleaved-caspase-3 and Bax, were more significantly up-regulated by the combined treatment than by TMZ used alone. In addition, p-Akt and Bcl-2, which can promote TMZ resistance, were markedly decreased by LY294002. These findings suggest that LY294002 enhances the cytotoxicity of TMZ by down‑regulation of the PI3K/Akt pathway.

MicroRNA-300 inhibited glioblastoma progression through ROCK1

Glioblastoma is a common type of brain aggressive tumors and has a poor prognosis. MicroRNAs (miRNAs) are a class of small, endogenous and non-coding RNAs that play crucial roles in cell proliferation, survival and invasion. Deregulated expression of miR-300 has been studied in a lot of cancers. However, the role of miR-300 in glioblastoma is still unknown. In this study, we demonstrated that miR-300 expression was downregulated in glioblastoma tissues compared with the normal tissues. Lower expression level of miR-300 was observed in thirty cases (75 %, 30/40) of glioblastoma samples compared with the normal samples. Moreover, the overall survival of glioblastoma patients with lower miR-300 expression level was shorter than those with higher miR-300 expression level. In addition, miR-300 expression was also downregulated in glioblastoma cell lines. Overexpression of miR-300 inhibited cell proliferation, cell cycle and invasion in glioblastoma cell line U87 and U251. Moreover, we identified ROCK1 as a direct target of miR-300 in U87 and U251 cells. Overexpression of ROCK1 partially rescued the miR-300-mediated cell growth. ROCK1 expression levels in glioblastoma tissues were higher than that in normal tissues. ROCK1 expression levels were higher in thirty-one cases of glioblastoma samples than their normal samples. Furthermore, the expression level ROCK1 was inversely correlated with the expression level of miR-300. Importantly, overexpression of miR-300 suppressed glioblastoma progression in an established xenograft model. In conclusion, we revealed that miR-300 might act as a tumor suppressor gene through inhibiting ROCK1 in glioblastoma.

Genipin Inhibits LPS-Induced Inflammatory Response in BV2 Microglial Cells.

Genipin, an aglycon of geniposide, has been reported to have anti-inflammatory effect. However, the anti-inflammatory activity of genipin on LPS-stimulated BV2 microglial cells has not been reported. In this study, we investigated the molecular mechanisms responsible for the anti-inflammatory activity of genipin both in vivo and in vitro. The levels of TNF-α, IL-1β, NO and PGE2 were detected by ELISA. The expression of Nrf2, HO-1, and NF-κB were detected by western blot analysis. In vivo, genipin significantly attenuated LPS-induced memory deficit in the Morris water maze and passive avoidance tasks. Genipin also inhibited LPS-induced TNF-α and IL-1β expression in brain tissues. In vitro, our results showed that genipin inhibited LPS-induced TNF-α, IL-1β, NO and PGE2 production in a concentration-dependent manner. Genipin also suppressed LPS-induced NF-κB activation. In addition, the expression of Nrf2 and HO-1 were up-regulated by treatment of genipin. Furthermore, the inhibition of genipin on inflammatory mediator production was attenuated by transfection with Nrf2 siRNA. In conclusion, genipin inhibited LPS-induced inflammatory response by activating Nrf2 signaling pathway in BV2 microglia.

Antagomirs Targeting MiroRNA-134 Attenuates Epilepsy in Rats through Regulation of Oxidative Stress, Mitochondrial Functions and Autophagy

The effects of the existing anti-epileptic drugs are unsatisfactory to almost one third of epileptic patients. MiR-134 antagomirs prevent pilocarpine-induced status epilepticus. In this study, a lithium chloride-pilocarpine-induced status epilepticus model was established and treated with intracerebroventricular injection of antagomirs targeting miR-134 (Ant-134). The Ant-134 treatment significantly improved the performance of rats in Morris water maze tests, inhibited mossy fiber sprouting in the dentate gyrus, and increased the survival neurons in the hippocampal CA1 region. Silencing of miR-134 remarkably decreased malonaldehyde and 4-hydroxynonenal levels and increased superoxide dismutase activity in the hippocampus. The Ant-134 treatment also significantly increased the production of ATP and the activities of mitochondrial respiratory enzyme complexes and significantly decreased the reactive oxygen species generation in the hippocampus compared with the status epilepticus rats. Finally, the Ant-134 treatment remarkably downregulated the hippocampal expressions of autophagy-associated proteins Atg5, beclin-1 and light chain 3B. In conclusion, Ant-134 attenuates epilepsy via inhibiting oxidative stress, improving mitochondrial functions and regulating autophagy in the hippocampus.

Antagomirs Targeting MicroRNA-134 Increase Limk1 Levels After Experimental Seizures in Vitro and in Vivo

Background: MiR-134 is enriched in dendrites of hippocampal neurons and plays crucial roles in the progress of epilepsy. The present study aims to investigate the effects of antagomirs targeting miroRNA-134 (Ant-134) on limk1 expression and the binding of miR-134 and limk1 in experimental seizure. Methods: Status epilepticus (SE) rat model was established by lithium chloride-pilocarpine injection and was treated with Ant-134 by intracerebroventricular injection. Low Mg2+-exposed primary neurons were used as an in vitro model of SE. The expression of miR-134 was determined using real-time PCR. Protein expressions of limk1 and cofilin were determined by Western blotting. Luciferase reporter assay was used to examine the binding between miR-134 and limk1 3’-untranslated region. Results: The expression of miR-134 was markedly enhanced in hippocampus of the SE rats and low Mg2+-exposed neurons. Ant-134 increased the expression of limk1 and reduced the expression of cofilin in the SE hippocampus and Low Mg2+-exposed neurons. In addition, luciferase reporter assay confirmed that miR-134 bound limk1 3’-UTR. MiR-134 overexpression inhibited limk1 mRNA and protein expressions in neurons. Conclusion: Blockage of miR-134 upregulates limk1 expression and downregulated cofilin expression in hippocampus of the SE rats. This mechanism may contribute to the neuroprotective effects of Ant-134.

Cdc20 overexpression is involved in temozolomide-resistant glioma cells with epithelial-mesenchymal transition

ABSTRACT Glioma remains one of the most aggressive and lethal cancers in central nervous system. Temozolomide (TMZ) is the most commonly used chemotherapeutic agent in gliomas. However, therapeutic benefits of TMZ could be very limited and all patients would finally suffer from tumor progression as the tumors develop resistance to TMZ. In this study, we aim to investigate the underlying mechanism of chemoresistance in glioma cell line and to identify whether there is still a close link between epithelial-mesenchymal transition (EMT) and TMZ resistance in gliomas. The real-time RT-PCR and Western blotting were used to measure the expression of EMT markers in TMZ-resistant cells. The migration and invasion assays were conducted to detect the cell motility activity in TMZ-resistant cells. The transfection was used to down-regulate the Cdc20 expression. The student t-test was applied for data analysis. We established stable TMZ-resistant glioma cells and designated as TR. Our results revealed that TR cells exhibited a significantly increased resistance to TMZ compared with their parental cells. Moreover, TMZ-resistant cells had acquired EMT-like changes. For the mechanism study, we measured a significant increased expression of CDC20 and decreased expression of Bim in TR cells. Moreover, upon suppression of CDC20 by shRNA transfection, TR cells underwent a reverse of EMT features. Importantly, knockdown of CDC20 enhanced the drug sensitivity of TR cells to TMZ. Our results suggested that inactivation of CDC20 could contribute to the future therapy that possibly overcomes drug resistance in human cancers.

Abstract P3-07-22: RS1008805 polymorphism in CYP19A1 gene is related to the efficacy of hormone therapy in early breast cancer

Purpose It has been suggested that genetic polymorphisms in CYP19A1 gene were related to aromatase activity as well as circulating steroid hormone levels in postmenopausal women. Therefore, it is biologically reasonable that CYP19A1 rs1008805 (A/G) polymorphism may be associated with clinical outcome for hormone therapy. Methods Genotyping for CYP19A1 polymorphism rs1008805 was performed on 287 women with HR-positive early breast cancer. Associations were evaluated between CYP19A1 rs1008805 genotypes and disease-free survival (DFS). Results Based on the analysis of the whole cohort, no significant differences were observed between rs1008805 genotypes and DFS, 5-year DFS rate. However, in postmenopausal women, rs1008805 genotypes were significantly associated with DFS and 5-years DFS rate (AA versus AG versus GG: 89.2 months versus 58.2 versus 32.7 months; 55.9% versus 47.8% versus 0%; P = 0.019). In addition, when the population was subgrouped into two cohorts, women carrying GG variant have a poorer DFS, 5-years DFS rate (GG versus AA or AG: 32.7 months versus 70.6 months; 0% versus 52.1%; HR, 3.613; 95% CI,1.380-9.457; P = 0.005). Furthermore, being adjusted by patients features in multivariate analyses, GG genotype remained an independent prognostic factor for DFS (HR, 3.439; 95% CI, 1.251-9.456; P = 0.017). However, there was no significant differences in DFS and 5-years DFS rate between women harbor the minor allele and those with the homozygous common allele (AG or GG versus AA: 52.4 months versus 89.2 months; 41.0% versus 52.9%; HR, 1.288; 95% CI, 0.705-2.353; P = 0.408). In addition, there were no differences between rs1008805 polymorphisms and DFS among premenopausal women. Conclusions The homozygous minor allele (GG) of CYP19A1 rs1008805 is significantly associated with worse clinical outcome of hormone therapy in postmenopausal HR-positive early breast cancer patients. If confirmed, genotyping for CYP19A1 polymorphisms rs1008805 may provide predictive information for better selection of endocrine treatment. Citation Format: Wang X, Shao X, Zheng Y, Shi L, Huang Y. RS1008805 polymorphism in CYP19A1 gene is related to the efficacy of hormone therapy in early breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-22.

Abstract P6-03-19: Rs1008805 polymorphism in the CYP19A1 gene is related to the prognosis of stage I–II and operable stage III breast cancer

Purpose Aromatase, encoded by CYP19A1 gene, is a rate-limiting enzyme in the conversion of androgens into estrogens. It has been demonstrated that genetic polymorphisms in CYP19A1 gene were significantly correlated with altered hormone levels in urine and serum, providing an explication for an elevated risk for progression in relation with increasing estrogen exposure. Consequently, it is biologically plausible that CYP19A1 gene polymorphisms may be related to the prognosis of breast cancer. Methods CYP19A1 gene rs1008805 polymorphism were genotyped on 406 Chinese Han women with stage I-II and operable stage III breast cancer. Associations were evaluated between CYP19A1 rs1008805 genotypes and disease-free survival (DFS). Results Totally, there were 200 (49.3%) patients with AA genotype, 169 (41.6%) with AG variant, and 37 (9.1%) carrying GG variant. No significant differences were found in DFS among the whole population with these three genotypes. However, postmenopausal women with GG variant had a poorer DFS when compared with those carrying AG or AA genotype (13.7 months versus 56.3 months; HR, 2.462; 95 % CI, 1.310-4.628; P = 0.004). And what9s more, being adjusted by patients features in multivariate analyses, GG genotype remained an independent prognostic factor for DFS (HR, 2.706; 95 % CI, 1.393-5.257; P = 0.003). Premenopausal women with GG variant had a marginally improved DFS when compared with those carrying AG or AA genotypes (87.0 months versus 48.7 months; HR, 0.544; 95% CI, 0.295-1.003; P = 0.051). However, this difference was not confirmed by multivariate analyses. Conclusions The present study indicated that GG genotype of rs1008805 SNP in the first exon of CYP19A1 gene was significantly related to a worse DFS in postmenopausal women with early breast cancer. This founding is novel, if confirmed, CYP19A1 rs1008805 genotypes may turn to be a prognostic biomarker for early breast cancer. Citation Format: Shao X, Zheng Y, Shi L, Huang Y, Wang X. Rs1008805 polymorphism in the CYP19A1 gene is related to the prognosis of stage I–II and operable stage III breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-03-19.