Benzo(a)pyrene affects proliferation with reference to metabolic genes and ROS/HIF-1α/HO-1 signaling in A549 and MCF-7 cancer cells.

Benzo(a)pyrene (BaP) is a representative polycyclic aromatic hydrocarbon (PAH) compound, which has been implicated in cancer initiation and promotion. Although BaP is one of the most extensively studied pollutants, the underlying mechanisms through which BaP affects reactive oxygen species (ROS)/hypoxia-inducible factor 1α (HIF-1α)/heme oxygenase 1(HO-1) signaling during lung or breast carcinogenesis are not yet fully understood. In this study, we analyzed the effects of 0 (control), 1, 5, or 25 µM BaP exposure on A549 and MCF-7 cancer cells, by evaluating cell viability, cell cycle, and regulatory protein expression, metabolic gene expression, and ROS/HIF-1α/HO-1 signaling. Cell viability increased following exposure to 1 and 5 µM BaP in A549 cells but decreased following exposure to all concentrations of BaP in MCF-7 cells. BaP significantly increased the proportions of cells in S and G2/M phases, with concomitant reductions in the proportions of cells in G0/G1 phase, following 5 and 25 µM exposure, which was accompanied by the upregulation of the regulatory proteins cyclin A, cyclin B, cyclin-dependent kinase (CDK)1, and CDK2. The subsequent upregulation of cytochrome p450 (CYP)1A1, CYP1B1, CYP3A4, epoxide hydrolase (EH), aldo-keto reductase (AKRC1) expression, and the attenuation of multi-drug resistance protein 4 (MRP4), glutathione-S-transferase (GST)1A1, and GST1B1 were also observed in both cell lines. Moreover, the induction of ROS and the modulation of HIF-1α and HO-1 were observed after BaP exposure. Taken together, these findings suggest that BaP affects proliferation with reference to metabolic genes and ROS/HIF-1α/HO-1 signaling in A549 and MCF-7 cancer cells.

Synergistic antitumor effect of resveratrol and sorafenib on hepatocellular carcinoma through PKA/AMPK/eEF2K pathway.

Although sorafenib (Sor) is the only effective drug for hepatocellular carcinoma (HCC), its therapeutic potential to date is mainly limited to the low tumor response. This study was designed to explore whether resveratrol (Res) could potentiate the anticancerous activity of Sor. We used HepG2 and Huh7 HCC cell lines and BALB/c nude mice for in vitro and in vivo studies, respectively. The cultured cell lines and tumor induction in the mice were treated with different concentrations of Res and Sor alone, and the combination of Res and Sor to observe the antitumor effects. Significant inhibitory effects were observed in the combined treatment of Res and Sor compared to Res and Sor alone treatments both in vitro and in vivo as demonstrated by significantly high number of S phase cells and apoptotic cells. Moreover, these findings were accompanied by the reduction of CDK2, CDC25A, PKA, p-AMPK, and eEF2K protein levels and the increment of cyclin A, cleavage caspase-3, caspase-8, and caspase-9 protein levels. The combinational treatment exhibited more significant anticancerous effect than the Res and Sor alone treatments in mice-bearing HepG2 xenograft. Overall, our results suggest that PKA/AMPK/eEF2K pathway is involved in the synergistic anticancerous activity of Res and Sor combination treatment in HCC cells. Thus, Res and Sor combination therapy may be promising in increasing the tumor response of Sor in the future.

Induction of proliferative and mutagenic activity by benzo(a)pyrene in PC-3 cells via JAK2/STAT3 pathway.

Environmental carcinogen benzo(a)pyrene (BaP) is a representative compound of polycyclic aromatic hydrocarbons (PAHs). BaP is strongly associated with prostate carcinogenesis. However, the molecular mechanism of BaP in development of prostate carcinoma remains largely unknown. The aim of this study was to investigate the effect and mechanism of BaP on the development in prostate cancer. PC-3 cells were exposed to different concentrations of BaP for 24, 48, 72 h, respectively. We analyzed the effect of BaP on PC-3 cell viability, cell cycle, DNA strand breaks, mutagenic activity, and migration. The expression of associated regulatory genes and the effect of JAK2/STAT3 signaling were also measured to explore the relationships among BaP metabolism, the JAK2/STAT3 pathway and proliferative activity in PC-3 cells. We observed significant effects on proliferation, DNA strand breaks and mutagenic activity after BaP exposure in PC-3 cells, and inhibitors of CYP1 and the AhR transcription factor α -naphthoflavone (ANF) and CH223191 treatment clearly reduced both cell survival and mutagenesis associated with BaP exposure. Reduction in G0-G1 phase population and elevation in S phase were observed after BaP exposure. Migratory cells for PC-3 were significantly increased. The results were further confirmed by the expression of mRNA levels in the significant increments of Snail, Slug, MMP-9, CYP1A1, CYP1B1, CycilnD1, CDK4 and significant reduction of E-cadherin. Significant enhancements were found in the expression of JAK2, STAT3 after BaP treatment. Additionally, activator IL-6 significantly enhanced the effect of BaP on cell survival, mutagenic activity, Cyclin D1, CDK4, Snail, and JAK2/STAT3 expression in PC-3 cells. Significant reductions in cell survival, mutagenic activity, Cyclin D1, CDK4, Snail, and JAK2/STAT3 expression were found after inhibitor AG490, ANF and CHJ223191 treatment. These findings reveal that BaP enhances the proliferative and mutagenic activity via JAK2-STAT3 pathway in PC-3 cells, and provide the additional evidence to understand the crucial role of BaP in prostate cancer carcinogenesis.

Calcium promotes differentiation in ameloblast-like LS8 cells by downregulation of phosphatidylinositol 3 kinase /protein kinase B pathway.

OBJECTIVES: To investigate the effect and mechanism of calcium on LS8 cell differentiation, especially on phosphatidylinositol 3 kinase (PI3K) /protein kinase B(AKT) pathway. MATERIALS AND METHODS: Ameloblast-like LS8 cell line was used and additional 0-3.5 mmol/L calcium chloride was treated for 24 h, 48 h. Cell viability and morphological changes, cell cycle and associated regulatory proteins were analyzed. RESULTS: No significant effects on morphological changes were observed. Decreased cell viability and increased S phase cells were accompanied by the significant decrease of cyclin A and cyclin B proteins, and significant increase of cyclin D protein in LS8 cells. Additionally, kallikrein-4 and amelotin expressions were significantly increased. Finally, the levels of PI3K, AKT, p-AKT and forkhead box O3 (FOXO3) significantly downregulated after calcium treatment in LS8 cells. CONCLUSIONS: Calcium inhibit proliferation and promotes differentiation in LS8 cells, this is closely related to the downregulation of PI3K/AKT signal in LS8 cells.

ß-Cryptoxanthin induced anti-proliferation and apoptosis by G0/G1 arrest and AMPK signal inactivation in gastric cancer.

ß-Cryptoxanthin has been associated with reduced-risk of some cancers. However, the mechanisms of ß-cryptoxanthin still remain unclearly understood in gastric cancer (GC). In this study, we examined the effect of ß-cryptoxanthin on AMPK signal in human gastric cancer cells. AGS and SGC-7901 cells were treated with ß-cryptoxanthin (0-40 µM) and AGS cells were injected in BALB/c (nu/nu) mice to analyze the effect of ß-cryptoxanthin on GC. We found that ß-cryptoxanthin induced inhibitory effect on the cell viability in a time- and concentration-dependent manner. The number of migrated cells and protein levels of matrix metalloproteinase (MMP) -2 and MMP-9 were obviously decreased. ß-Cryptoxanthin treatment induced G0/G1 arrest, and reduced the expression of Cyclin E, Cyclin D1, cyclin-dependent kinases (CDK) of CDK4 and CDK6, and increased the expression of p53 and p21 in the two GC cells. Additionally, ß-cryptoxanthin induced apoptosis and increased the expression of cleaved caspase-3, -8, -9 as well as cytochrome C (cyt C). ß-Cryptoxanthin induced AMP-activated protein kinase (AMPK) signal inactivation by the down-regulation of protein kinase A (PKA), p-AMPK, eukaryotic elongation factor 2 kinase (eEF2k). Furthermore, ß-cryptoxanthin inhibited tumor growth through suppressing the tumor volume and weight, inducing apoptotic cells. Besides, ß-cryptoxanthin induced significant reductions of vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9). In conclusion, our data provide the novel evidence to understand the mechanism of anti-pcancer of ß-cryptoxanthin and indicate that ß-cryptoxanthin can serve as a promising chemopreventive agent against gastric cancer.

Acute benzo[a]pyrene treatment causes different antioxidant response and DNA damage in liver, lung, brain, stomach and kidney.

Acute effects of oxidative damage induced by benzo[a]pyrene (B[a]P) on various organs are still not clear. In this study, we investigated oxidative stress and DNA damage in liver, lung, stomach, brain and kidney of ICR male mice induced by acute B[a]P treatment. B[a]P treatment led to a significant decrease at the different doses in body weight. For the variations of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione (GSH) and GSH/GSSG, significant increases were observed at 24 h, then decreased till 72 h after B[a]P injection. The increase percent indicated in a dose- dependent decrease manner. However, glutathione peroxidase (GPx), GSSG and MDA were significantly increased in a time- and dose-dependent increase manner. DNA damage showed the significant and top levels at 24 h, and increased in proportion to the doses of B[a]P treatment. The total induction could be indicated by the variation of MDA at 24 h after B[a]P injection and showed the following order of predominance: lung > liver > kidney = stomach > brain. This was further certificated by histopathological changes in the examined organs. Additionally, the levels of serum glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), and blood urea nitrogen (UN), creatinine were also significantly increased at 24 h after B[a]P injection. These findings suggested the disturbance of antioxidant responses and aggravation of DNA damages, and the different responses on various organs induced by acute B[a]P treatment in organism.

[Application of 18F-FDG PET/CT scan in following-up of nasopharyngeal carcinoma after radiotherapy].

BACKGROUND & OBJECTIVE: Local relapse,tumor residue, and whole body metastases of nasopharyngeal carcinoma (NPC) after radiotherapy were mainly confirmed by CT, MRI, SPE/CT, and PET examinations. This study was to discuss the value of F-18-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (PET/CT) in detecting suspected recurrence or tumor residue, and whole body metastases of NPC after radiotherapy. METHODS: PET/CT were performed on 38 NPC patients 3-36 months after radiotherapy. The images of PET/CT, CT, and PET were observed. PET standardized uptake value (SUV) was calculated, and SUV of > 2.5 was considered as positive. The Patients were divided into 4 groups by diagnosis: (1) no recurrence/residue, and no whole body metastases; (2) with recurrence/residue, but no whole body metastases; (3) no recurrence/residue, but with whole body metastases; (4) with both recurrence/residue and whole body metastases. Diagnoses of all patients were referred to the proved follow-up clinical information. The following-up time was 6-10 months. RESULTS: The sensitivity, and specificity of PET/CT (100%,and 89.5%) were better than that of CT alone (77.8%, and 84.2%), a litter better than that of PET alone (100%, and 80.0%). CONCLUSIONS: FDG-PET scan is a better tool than CT alone for the detection of recurrene or residue, and whole body metastases of NPC, a litter better than PET alone. PET/CT may provide valuable information for judging whether the focus is metastasis.