Isorhamnetin (ISO), a flavonoid compound isolated from sea-buckthorn ( Hippophae rhamnoides L.) fruit, has anti-inflammatory effects.

Pingyangmycin is an anticancer drug known as bleomycin A5 (A5), discovered in the Pingyang County of Zhejiang Province of China. Bleomycin (BLM) is a mixture of mainly two compounds (A2 and B2), which is on the World Health Organization’s list of essential medicines. Both BLM and A5 are hydrophilic molecules that depend on transporters or endocytosis receptors to get inside of cells. Once inside, the anticancer activities rely on their abilities to produce DNA breaks, thus leading to cell death. Interestingly, the half maximal inhibitory concentration (IC₅₀) of BLMs in different cancer cell lines varies from nM to μM ranges. Different cellular uptake, DNA repair rate, and/or increased drug detoxification might be some of the reasons; however, the molecules and signaling pathways responsible for these processes are largely unknown. In the current study, we purified the A2 and B2 from the BLM and tested the cytotoxicities and the molecular mechanisms of each individual compound or in combination with six different cell lines, including a Chinese hamster ovary (CHO) cell line defective in glycosaminoglycan biosynthesis. Our data suggested that glycosaminoglycans might be involved in the cellular uptake of BLMs. Moreover, both BLM and A5 shared similar signaling pathways and are involved in cell cycle and apoptosis in different cancer cell lines.

Cytochrome b5 reductase 2 (CYB5R2) is a potential tumor suppressor that inhibits cell proliferation and motility in nasopharyngeal carcinoma (NPC). Inactivation of CYB5R2 is associated with lymph node metastasis in NPC. This study aimed to explore the mechanisms contributing to the anti-neoplastic effects of CYB5R2. Polymerase chain reaction (PCR) assays were used to analyze the transcription of 84 genes known to be involved in representative cancer pathways in the NPC cell line HONE1. NPC cell lines CNE2 and HONE1 were transiently transfected with CYB5R2, and data was validated by real-time PCR. A chick chorioallantoic membrane (CAM) embryo model was implanted with CYB5R2-expressing CNE2 and HONE1 cells to evaluate the effect of CYB5R2 on angiogenesis. An immunohistochemical assay of the CAM model was used to analyze the protein expression of vascular endothelial growth factor (VEGF). In CYB5R2-transfected NPC cells, PCR assays revealed up-regulated mRNA levels of Fas cell surface death receptor (FAS), FBJ murine osteosarcoma viral oncogene homolog (FOS), phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1), integrin beta 3 (ITGB3), metastasis suppressor 1 (MTSS1), interferon beta 1 (IFNB1), and cyclin-dependent kinase inhibitor 2A (CDKN2A) and down-regulated levels of integrin beta 5 (ITGB5), insulin-like growth factor 1 (IGF1), TEK tyrosine kinase (TEK), transforming growth factor beta receptor 1 (TGFBR1), and VEGF. The angiogenesis in the CAM model implanted with CYB5R2-transfected NPC cells was inhibited. Down-regulation of VEGF by CYB5R2 in NPC cells was confirmed by immunohistochemical staining in the CAM model. CYB5R2 up-regulates the expression of genes that negatively modulate angiogenesis in NPC cells and down-regulates the expression of VEGF to reduce angiogenesis, thereby suppressing tumor formation.

To explore the mechanism of HIF-1α promoting the proliferation, invasion and metastasis of nasopharyngeal carcinoma cells by regulating the expression of MMP-2. 30 nasopharyngeal carcinoma tissues and 30 normal nasopharyngeal epithelial tissues were collected, and the expression of HIF-1α and MMP-2 in the nasopharyngeal carcinoma, normal nasopharyngeal epithelial tissues and their hypoxic environment were systematically analyzed by qRT-PCR and western blot techniques. Lentivirus transfection technology was used to regulate the expression of HIF-1α and MMP-2 genes in the HONE1 cell line under hypoxic environment, and to explore the interaction mechanism of HIF-1α and MMP-2 genes and their role in the proliferation, invasion and metastasis of nasopharyngeal carcinoma. Furthermore, the cytological behavior changes regulated by HIF-1α and MMP-2 genes were further explored by gene chip technology. The expressions of HIF-1α and MMP-2 in nasopharyngeal carcinoma tissues were significantly higher than those in normal nasopharyngeal epithelial tissues (P < 0.05). Compared with normoxic group, the expression of HIF-1α and MMP-2 in the nasopharyngeal carcinoma cell line HONE1 increased in hypoxic group (P < 0.05). Compared with NC-siRNA group, the expression of HIF-1α in si-HIF-1α group decreased, and the cell proliferation ability and invasion and metastasis ability decreased (P < 0.05). PCR array analysis revealed that the mRNA expressions of FAS, BRCA1, TIMP-1 genes were up-regulated in nasopharyngeal carcinoma HONE1 cells with HIF-1α gene silencing. AKT1, VEGFA, MET, MMP-2, MMP-9 and MTA2 were down-regulated. Compared with NC-siRNA group, the expression of MMP-2 in si-MMP-2 group decreased, and the ability of cell proliferation and invasion and metastasis decreased (P < 0.05). HIF-1α could inhibit the proliferation, invasion and metastasis of nasopharyngeal carcinoma by regulating the expression of MMP-2, thus inhibiting tumor growth. Therefore, HIF-1α and MMP-2 might become important therapeutic targets to inhibit the growth, invasion and metastasis of nasopharyngeal carcinoma.

Pingyangmycin is a clinically used anticancer drug and induces lung fibrosis in certain cancer patients. We previously reported that the negatively charged cell surface glycosaminoglycans are involved in the cellular uptake of the positively charged pingyangmycin. However, it is unknown if pingyangmycin affects glycosaminoglycan structures. Seven cell lines and a Lewis lung carcinoma‐injected C57BL/6 mouse model were used to understand the cytotoxicity of pingyangmycin and its effect on glycosaminoglycan biosynthesis. Stable isotope labelling coupled with LC/MS method was used to quantify glycosaminoglycan disaccharide compositions from pingyangmycin‐treated and untreated cell and tumour samples. Pingyangmycin reduced both chondroitin sulphate and heparan sulphate sulphation in cancer cells and in tumours. The effect was persistent at different pingyangmycin concentrations and at different exposure times. Moreover, the cytotoxicity of pingyangmycin was decreased in the presence of soluble glycosaminoglycans, in the glycosaminoglycan‐deficient cell line CHO745, and in the presence of chlorate. A flow cytometry‐based cell surface FGF/FGFR/glycosaminoglycan binding assay also showed that pingyangmycin changed cell surface glycosaminoglycan structures. Changes in the structures of glycosaminoglycans may be related to fibrosis induced by pingyangmycin in certain cancer patients.