Cytotoxic and cell cycle effects induced by two herbal extracts on human cervix carcinoma and human breast cancer cell lines

Rosmarinic acid reduces the resistance of gastric carcinoma cells to 5-fluorouracil by downregulating FOXO4-targeting miR-6785-5p

OBJECTIVE

Chemoresistance has been a major problem in cancer chemotherapy. The present study aimed to investigate the effect of Rosmarinic acid (RA) on chemoresistance to 5-Fu and its molecular mechanism in gastric carcinoma.

METHODS

CCK8 cell proliferation and apoptosis assay were used to evaluate the effect of RA on chemoresistance to 5-Fu in GC cells. RNA microarray was used to identify miRNA involved. Expression level of miRNA in GC cells was determined by RT-PCR. Down- or up-regulating of miRNA in the GC cells was performed by transfection of RNA interference or expression vectors in the GC cells. Double luciferase reporter assay was used to verify miRNA target genes. Expression of P-glycoprotein and Bax was analyzed with Western blot.

RESULTS

RA treated SGC7901/5-Fu cells showed significant increased chemosensitivity to 5-Fu. The IC50 of 5-Fu was significantly reduced in RA treated SGC7901/5-Fu cells (70.43 ± 1.06 μg/mL) compared to untreated SGC7901/5-Fu cells (208.6 ± 1.09 μg/mL) (P < 0.05). Apoptosis rate was significantly increased in RA+5-Fu treated SGC7901/5-Fu cells compared to 5-FU treatment alone (P < 0.01). Two miRNAs, namely miR-642a-3p and miR-6785-5p, were identified to be involved in the chemo-sensitizing effect of RA in the SGC7901/5-Fu cells. RA treated SGC7901/5-Fu cells showed reduced expression levels of miR-642a-3p and miR-6785-5p compared to untreated SGC7901/5-Fu cells (P < 0.05). Down- or up-regulation of miR-6785-5p increased or reduced chemosensitivity of gastric carcinoma cells to 5-Fu, respectively. RA treated SGC7901/5-Fu and the SGC7901/5-Fu-Si cells showed significantly increased FOXO4 expression (P < 0.01). Double luciferase reporter assay confirmed miR-6785-5p directly targets FOXO4 to regulate its expression. RA significantly reduced P-gp expression and increased Bax expression in SGC7901/5-Fu and the SGC7901/5-Fu-Si cells (P < 0.05).

CONCLUSION

RA enhances chemosensitivity of resistant gastric carcinoma SGC7901 cells to 5-Fu by downregulating miR-6785-5p and miR-642a-3p and increasing FOXO4 expression. These study suggest the potential for RA as a multidrug resistance-reversing agent in GC.

Thymus vulgaris (thyme) inhibits proliferation, adhesion, migration, and invasion of human colorectal cancer cells

Colorectal cancer (CRC) remains one of the most common malignancies and a leading cause of cancer-related deaths. Its prognosis remains poor for patients with several grades of this disease. This underscores the need for alternative modalities, such as herbal medicines, to treat this disease. A commonly used plant that appears to be of high medicinal value is Thymus vulgaris L. However, the effects of this plant on the malignant behavior of human CRC cells remains poorly investigated. This study was undertaken to determine the anticancer efficacy of T. vulgaris extract (TVE) in CRC cells. Our results show that TVE inhibits proliferation in a concentration- and time-dependent fashion. This decreased proliferation was concomitant with increased apoptotic cell death as evidenced by increased caspase3/7 activity. Moreover, TVE also decreased adhesion to fibronectin in a concentration-dependent manner. The migratory and invasive capacities of HCT116 cells were significantly inhibited by TVE. Taken together, these data suggest that the TVE inhibits malignant phenotype of colon cancer cells. Therefore, T. vulgaris could have an anticancer effect and that some of its bioactive compounds may prove to be effective treatment modalities for human CRC.

Organotypic culture of breast tumor explants as a multicellular system for the screening of natural compounds with antineoplastic potential

Breast cancer is the leading cause of death in women worldwide. The search for novel compounds with antitumor activity, with less adverse effects and higher efficacy, and the development of methods to evaluate their toxicity is an area of intense research. In this study we implemented the preparation and culture of breast tumor explants, which were obtained from precision-cut breast tumor slices. In order to validate the model we are proposing to screen antineoplastic effect of natural compounds, we selected caffeic acid, ursolic acid, and rosmarinic acid. Using the Krumdieck tissue slicer, precision-cut tissue slices were prepared from breast cancer samples; from these slices, 4 mm explants were obtained and incubated with the selected compounds. Viability was assessed by Alamar Blue assay, LDH release, and histopathological criteria. Results showed that the viability of the explants cultured in the presence of paclitaxel (positive control) decreased significantly (P < 0.05); however, tumor samples responded differently to each compound. When the explants were coincubated with paclitaxel and compounds, a synergic effect was observed. This study shows that ex vivo culture of breast cancer explants offers a suitable alternative model for evaluating natural or synthetic compounds with antitumor properties within the complex microenvironment of the tumor.