Glabridin arrests cell cycle and inhibits proliferation of hepatocellular carcinoma by suppressing braf/MEK signaling pathway.

Glabridin, an isoflavone isolated from licorice, owns a variety of pharmacological effects. Several reports have demonstrated that glabridin could regulate multiple cellular signaling pathways to inhibit the progression of cancer. However, the target proteins have not been elucidated yet. We used shape screening and induced fit docking to screen the protein data bank against glabridin. Braf and MEK1/2, important intermediate molecules of the braf/MEK cascade, were identified as the potential targets of glabridin. The experimental data showed that glabridin could inhibit the phosphorylation of MEK1/2 and the phosphorylation levels of downstream molecules including ERK1/2 and transcription factors ATF1 and CREB, but had no effect on the phosphorylation of braf. In particular, the in vitro pull-down assay indicated that glabridin selectively bound to braf and MEK1/2. What is more, exposure to glabridin significantly suppressed the proliferation of hepatocellular carcinoma HepG2 cell line. In addition, glabridin might arrest cell cycle in G1 through downregulation of cyclinD3, CDK2, and CDK4. In conclusion, glabridin is a potential multi-molecule-targeting inhibitor in the field of clinical prevention or treatment of cancer.

Mitogen- and stress-activated Kinase 1 mediates Epstein-Barr virus latent membrane protein 1-promoted cell transformation in nasopharyngeal carcinoma through its induction of Fra-1 and c-Jun genes.

BACKGROUND: Mitogen- and Stress-Activated Kinase 1 (MSK1) is a nuclear kinase that serves as active link between extracellular signals and the primary response of gene expression. However, the involvement of MSK1 in malignant transformation and cancer development is not well understood. In this study, we aimed to explore the role of MSK1 in Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1)-promoted carcinogenesis of nasopharyngeal carcinoma (NPC). METHODS: The level of MSK1 phosphorylation at Thr581 was detected by the immunohistochemical analysis in NPC tissues and normal nasopharynx tissues, and its correlation with LMP1 was analyzed in NPC tissues and cell lines. Using MSK1 inhibitor H89 or small interfering RNA (siRNA)-MSK1, the effects of MSK1 on LMP1-promoted CNE1 cell proliferation and transformation were evaluated by CCK-8 assay, flow cytometry and focus-forming assay respectively. Furthermore, the regulatory role of MSK1-mediated histone H3 phosphorylation at Ser10 on the promoter activity and expression of Fra-1 or c-Jun was determined by reporter gene assay and western blotting analysis. RESULTS: Immunohistochemical analysis revealed that the level of MSK1 phosphorylation at Thr581 was significantly higher in the poorly differentiated NPC tissues than that in normal nasopharynx tissues (P < 0.001). Moreover, high level of phosphorylated MSK1 was positively correlated with the expression of LMP1 in NPC tissues (r = 0.393, P = 0.002) and cell lines. MSK1 inhibitor H89 or knockdown of MSK1 by siRNA dramatically suppressed LMP1-promoted CNE1 cell proliferation, which was associated with the induction of cell cycle arrest at G0/G1 phase. In addition, the anchorage-independent growth promoted by LMP1 was blocked in MSK1 knockdown cells. When the activity or expression of MSK1 was inhibited, LMP1-induced promoter activities of Fra-1 and c-Jun as well as their protein levels were greatly reduced. It was found that only H3 WT, but not mutant H3 S10A, dramatically increased LMP1 induction of Fra-1 and c-Jun genes compared with mock cells. CONCLUSION: Increased MSK1 activity is critically important for LMP1-promoted cell proliferation and transformation in NPC, which may be correlated with its induction of Fra-1 and c-Jun through phosphorylation of histone H3 at Ser10.

The human ATF1 rs11169571 polymorphism associated with risk of nasopharyngeal carcinoma in Southern Chinese populations.

Our previous work reported activating transcription factor 1 (ATF1) is a promotive factor of nasopharyngeal carcinoma (NPC) tumorigenesis. This study is to further explore the association between the human ATF1 rs11169571 polymorphism and the risk of NPC occurrence. The association between ATF1 rs11169571 and risk of NPC occurrence was investigated in clinical samples of 560 patients and 661 controls obtained from southern China with high incidence of NPC. The genotypes were detected by PCR-RFLP. The differential expression activity of alleles -T and -C was analyzed with CNE-2 and C666-1 cells by luciferase reporter assay. Our data suggested that the allelic frequency and genotypes were significantly different between patients and controls. Compared to the TT homozygote, the TC and CC genotypes have been shown to be significantly decreased in NPC patients (OR = 0.494, 95% CI = 0.387-0.629, P < 0.001 and OR = 0.556, 95% CI = 0.364-0.851, P = 0.007, respectively). Compared to the -T allele, the -C allele is a factor of decreased risk in NPC (OR = 0.642, 95% CI = 0.537-0.767, P < 0.001). Luciferase reporter activity revealed that the -T allele confers a higher expression activity than the -C allele in CNE2 cells and C666-1 cells. In conclusion, ATF1 rs11169571 which could affect the expression of ATF1 is associated with NPC risk.

Association of microRNA-423 rs6505162 C>A polymorphism with susceptibility and metastasis of colorectal carcinoma.

Studies have evaluated the association between the SNP miRNA-423 rs6505162 C>A and cancer risk in several cancers with contradictory outcomes. It was reported that miRNA-423 rs6505162 C>A polymorphism was associated with the overall survival and the recurrence-free survival of colorectal carcinoma. However, no studies have reported the association between miRNA-423 rs6505162 C>A polymorphism and susceptibility of colorectal carcinoma.In this study, we investigated the association between miRNA-423 polymorphism with risk and clinicopathological parameters of colorectal carcinoma. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to genotype 117 colorectal carcinoma patients and 84 healthy controls.Our data indicated the frequencies of rs6505162 genotypes and alleles were significantly different between colorectal carcinoma patients and controls. Compared with CC homozygote, the AC heterozygote exhibited a significantly decreased risk of colorectal carcinoma; and the combination of AC and AA genotype was associated with decreased risk of colorectal carcinoma. The allele distribution of rs6505162 was significantly different between cases and controls. Furthermore, miR-423 rs6505162 C>A genotype showed a significant association with metastasis in patients (P = .022).Our study suggested that miR-423 rs6505162 C>A polymorphism was associated with the susceptibility and metastasis of colorectal carcinoma, and that miR-423 rs6505162 C>A polymorphism might be a potential biomarker for colorectal carcinoma.

Functional PIN1 promoter polymorphisms associated with risk of nasopharyngeal carcinoma in Southern Chinese populations.

Our previous work reported the association between two single nucleotide polymorphisms (SNPs) in PIN1 promoter and nasopharyngeal carcinoma (NPC) risk with a small sample size in a low incidence area. This study investigated the association between the two SNPs and NPC risk in 733 patients and 895 controls from a high incidence area. The results indicated the genotype and allele frequencies of -842G > C and -667C > T were both significantly different between patients and controls even using the resampling statistics. The -842GC and -667TT genotypes showed a significantly increased risk of NPC (OR = 1.977, 95% CI = 1.339-2.919, P = 0.001 and OR = 1.438, 95% CI = 1.061-1.922, P = 0.019, respectively). Compared to the most common -842G-667C haplotype, -842G-667T haplotype and -842C-667C haplotype showed a significantly increased risk of NPC (OR = 1.215, 95% CI = 1.053-1.402, P = 0.008 and OR = 2.268, 95% CI = 1.530-3.362, P = 0.001, respectively). Further reporter gene expression suggested that variant -842C-667C and -842G-667T were associated with an enhanced transcriptional activity. In conclusion, our findings suggest that -842G > C and -667C > T in PIN1 promoter are associated with NPC risk; as well as the promoter activity is mediated by functional PIN1 variants.

Niflumic acid exhibits anti-tumor activity in nasopharyngeal carcinoma cells through affecting the expression of ERK1/2 and the activity of MMP2 and MMP9.

Niflumic acid (NFA) was known to inhibit cell proliferation or migration in several types of cancer. However, the function of NFA in human nasopharyngeal carcinoma (NPC) cells was not clarified. The proliferation of NPC cell line CNE-2Z cells with NFA treatment was detected using the cell counting kit-8 method and transwell assay was employed to assess the effect of NFA on the CNE-2Z cell migration and invasion. The activity of MMP2 and MMP9 was detected by Gelatin Zymography. Cell cycle distribution and apoptosis were detected using flow cytometry. In vitro pull-down assay, western blot, and computational technique were applied to investigate the NFA regulating signaling pathway. Our results indicated that the growth capacity and colony formation potential of CNE-2Z cells in soft agar were significantly suppressed by treatment with NFA. NFA inhibited the proliferation of CNE-2Z cells in a concentration and time-dependent manner. NFA exerted an S phase arrest on the CNE-2Z cells in a concentration-dependent manner, while promoting apoptosis in a dose-dependent manner. Migration and invasion potential of CNE-2Z cells were decreased by NFA treatment in vitro. In vitro pull-down assay and molecular modeling indicated that NFA directly bound with early respond kinase 1 (ERK1). Finally, the anti-tumor effect of NFA was suggested to be mediated by inhibiting early respond kinases (ERK) expression and the MMP2 and MMP9 activities. NFA has proliferation-inhibiting, invasion-suppressing, cell cycle-blocking and apoptosis-promoting effects on CNE-2Z cells through regulation of ERK/MAPK and our results indicates that NFA may serve as a candidate of anticancer drug for NPC.

Cyclin D1 G870A polymorphism and risk of nasopharyngeal carcinoma: a case-control study and meta-analysis.

BACKGROUND: Cyclin D1 (CCND1) plays a key role in cell cycle regulation. It is a well-established human oncogene which is frequently amplified or overexpressed in cancers. The association between CCND1 G870A polymorphism and cancer risk has been widely assessed. However, a definitive conclusion between CCND1 G870A polymorphism and risk of nasopharyngeal carcinoma (NPC) remains elusive. METHODS: We firstly performed a hospital-based case-control study involving 165 NPC cases and 191 cancer-free controls in central-south China, and then conducted a meta-analysis with six case-control studies to evaluate the association between NPC risk and CCND1 G870A polymorphism. RESULTS: The case-control study found a significant association between CCND1 G870A polymorphism and NPC risk in various comparison models (AA vs. GG: OR = 2.300, 95% CI 1.089-4.857, p = 0.029; AG vs. GG: OR = 2.832, 95% CI 1.367-5.867, p = 0.005; AA/AG vs. GG: OR = 2.597, 95% CI 1.288-5.237, p = 0.008; AA vs. AG/GG: OR = 0.984, 95% CI 0.638-1.518, p = 0.944). Further meta-analysis showed that there was no significant association between CCND1 G870A polymorphism and NPC risk in overall analysis. In the stratified analysis by race, however, significant associations were only found in Caucasians (for the allele model A vs. G: OR = 0.75, 95% CI 0.59-0.97, p = 0.03; for the co-dominant model AA vs. GG: OR = 0.52, 95% CI 0.32-0.86, p = 0.01; for the dominant model AA/AG vs. GG: OR = 0.49, 95% CI 0.32-0.74, p<0.01; for the recessive model AA vs. AG/GG: OR = 0.90, 95% CI 0.61-1.34, p = 0.60). CONCLUSIONS: A significant association between CCND1 G870A polymorphism and NPC risk was found in the central-southern Chinese population. The meta-analysis indicated that CCND1 G870A polymorphism may contribute to the development of NPC in Caucasians.