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Quercetin is a potent cancer therapeutic agent and dietary antioxidant present in fruit and vegetables. Quercetin prevents tumor proliferation by inducing cell cycle arrest and is a well known cancer therapeutic agent and autophagy mediator. Recent studies showed that drug delivery by nanoparticles have enhanced efficacy with reduced side effects. In this regard, gold-quercetin into poly(DL-lactide-co-glycolide) nanoparticles was examined. In this study, we explored the role and possible underlying mechanisms of quercetin nanoparticle in regulation of antitumor activity in liver cancer cells. Treatment with quercetin nanoparticle effectively inhibited the liver cancer cell proliferation, cell migration and colony formation, thus suppressing liver cancer progression. Quercetin nanoparticle also upregulated apoptosis markedly. Further study suggested that quercetin nanoparticle accelerated the cleavage of caspase-9, caspase-3, and induced the up-releasing of cytochrome c (Cyto-c), contributing to apoptosis in liver cancer cells. Quercetin nanoparticles also promoted telomerase reverse transcriptase (hTERT) inhibition through reducing AP-2β expression and decreasing its binding to hTERT promoter. In addition, quercetin nanoparticle had an inhibitory role in cyclooxygenase 2 (COX-2) via suppressing the NF-κB nuclear translocation and its binding to COX-2 promoter. Quercetin nanoparticle also inactivated Akt and ERK1/2 signaling pathway. Taken together, our results suggested that quercetin nanoparticle had an antitumor effect by inactivating caspase/Cyto-c pathway, suppressing AP-2β/hTERT, inhibiting NF-κB/COX-2 and impeding Akt/ERK1/2 signaling pathways. Our results provided new mechanistic basis for further investigation of quercetin nanoparticles to find potential therapeutic strategies and possible targets for liver cancer inhibition.

Structural maintenance of chromosome 1 alpha (SMC1A) gene has been reported to be related to tumor development in some types of human cancers. However, the misregulation of SMC1A and its functions in castration-resistant prostate cancer (CRPC) have not been well understood. In the present study, we found that SMC1A was elevated in androgen-independent PCa cell lines PC-3 and DU-145 compared to androgen sensitive LNCap and 22RV1 cells by qPCR and western blot assay. Knockdown of SMC1A inhibited cell growth, colony formation and cell migration abilities of PC-3 and DU145 cells by MTT, colony formation and transwell assays, and affected cell cycle progression in PC-3 and DU145 cells by flow cytometry. Moreover, SMC1A knockdown significantly reduced tumor growth in vivo in a nude mouse model. Additionally, we also found that the expression of SMC1A gene was higher in prostate cancer tissues than in the adjacent normal tissues by immunohistochemical staining, and was positively correlated to tumor metastasis and recurrence by Oncomine database mining. Taken together, the present study indicates that SMC1A may play an important role in malignant transformation of PCa under conditions of androgen deprivation and act as a new target for PCa diagnosis and treatment.

Objective: To determine the inhibitory effect of 5-aza-2'-deoxycytidine (5-Aza-CdR) on the growth of human colon carcinoma cells and xenografts in nude mice, to observe its effect on CDH13 gene expression and methylation in the xenografts, and to explore the possible mechanisms., Methods: Human colon carcinoma cell line HCT116 cells were treated with 5-Aza-CdR, and the cell morphology was observe by phase contrast microscopy. The cell growth was assessed by MTT assay. A tumor-bearing mouse model was generated by subcutaneous inoculation of human colon carcinoma HCT116 cells into nude mice. The tumor growth in the nude mice was observed, the CDH13 gene expression and its methylation status in the tumors were detected using methylation specific PCR (MSP), RT-PCR, Western blotting and immunohistochemistry., Results: After treatment with 5-Aza-CdR, the inhibition rate of the growth of cultured HCT116 cells was increased as the concentration was increasing. The growth of the xenografts in nude mice was significantly inhibited, and the methylated CDH13 gene was reactivated. After 4 weeks of 5-Aza-CdR treatment, no significant difference was found between the body weights of nude mice in the 5-Aza-CdR group [(18.06 ± 1.29) g] and control group [(17.07 ± 0.84) g], (P > 0.10), and the average volume of xenografts of the 5-Aza-CdR group was (907.00 ± 87.29) mm(3), significantly smaller than the (1370.93 ± 130.20) mm(3) in the control group (P < 0.005). No expression of CDH13 gene was found in the control group. The expression of CDH13 gene in the 5-Aza-CdR group was increased along with the increasing concentration of 5-Aza-CdR., Conclusions: 5-Aza-CdR inhibits the growth of human colon cancer cells in culture and in nude mice, and induces the cancer cells to re-express CDH13 in nude mice. Its mechanism may be that demethylation of the methylated CDH13 promoter induced by 5-Aza-CdR restores CDH13 expression and thus inhibits the tumor growth in nude mice.

Background and Objective: Colon cancer is one of the most common malignant tumors, and its pathogenesis is not fully understood. Transcriptional silencing by DNA methylation is believed to be an important mechanism of carcinogenesis. E-cadherin can suppress tumor cell invasion and metastasis, and is considered as an invasion/metastasis suppressor gene. Inactivation of E-cadherin gene often occurs in colon carcinoma. This study was to investigate the correlation between E-cadherin gene expression and the methylation status of E-cadherin 5' CpG islands in human colon carcinoma cell line HT-29, and to explore the mechanism of carcinogenesis of colon cancer., Methods: Immunocytochemical dicho-step method and reverse transcription-polymerase chain reaction (RT-PCR) were used to detect the expression of E-cadherin protein and mRNA in HT-29 cells after 5-Aza-CdR treatment; methylation specific PCR was used to analyze the methylation status at promoter of E-cadherin gene., Results: The expression of E-cadherin gene could be restored by 5-Aza-CdR treatment, immunocytochemical staining showed the positive expression ratio of E-cadherin increased from (21+/-7)% (1 micromol/L) to (39+/-13)% (5 micromol/L); E-cadherin genes were methylated and not expressed in HT-29 cells in the colon carcinoma., Conclusions: E-cadherin methylation plays an important role in the carcinogenesis of colon carcinoma cells and can re-express after the treatment with 5-Aza-CdR.