Anti-proliferative activity of yerba mate (Ilex paraguariensis) aqueous extracts on human colorectal cancer cell lines

Background: Yerba mate, a popular, tea-like beverage prepared from the dried leaves of Ilex paraguariensis, is widely consumed, and has several reported health benefits. Compared with other herbal teas, the effect of yerba mate on human cells in the context of cancer has not been extensively studied. The method of extraction of bioactive compounds from the yerba mate leaves plays an important role in its effect on cancer cells. Methods: In this study we assessed the viability, anti-proliferative, and apoptotic effect of the aqueous yerba mate extract, prepared using the same conditions employed for consumption, on different human colorectal cancer cell lines (Caco-2, HT-29, and HCT116) and on the non-tumorigenic human colon epithelial cell line (NCM460).Results: Cytotoxicity of aqueous yerba mate extract was studied and a dose-dependent decrease in viability was observed in all the tested cell lines. At 24 hrs., viability decreased to 19.7% with Caco-2 cells, 2.7% with HCT116, and 8.4% with HT-29 cells at a concentration of 4.8 mg/mL of yerba mate extract. The effect was less prominent on the NCM460 cell line where the viability of cells at the same concentration was 65.2%. Yerba mate extract also showed concentration-dependent anti-proliferative effects as determined by the WST-1 proliferation kit. IC50 values ranged between 0.22-0.69 mg/mL at 24 hr for cell lines tested. To study whether cell death was due to apoptosis, Caco-2 cells were stained with Annexin V-FITC assay and an increase in the percentage of late apoptotic Caco-2 cells was observed with yerba mate extract at 0.6-4.8 mg/mL. Cell cycle analysis using DNA content by flow cytometry showed an increase in the percentage of Caco-2 cells in the subG0/G1 phase and the G0/G1 phase after treatment with 2.4 mg/mL extract. Collectively, our data suggest that yerba mate aqueous extract exhibits an anti-proliferative effect on tested cell lines by inducing apoptosis. Conclusions: Yerba mate aqueous extract exhibits a strong anti-proliferative activity against adenocarcinoma cell lines studied and constitutes a promising functional food adjuvant to anti-cancer therapy. Further work is needed to identify active components and mechanisms of action. Keywords: Aqueous extract, yerba mate, anti-proliferative activity, adenocarcinoma cell lines

Suppression of autophagy promotes fibroblast activation in p53-deficient colorectal cancer cells

Deficiency of p53 in cancer cells activates the transformation of normal tissue fibroblasts into carcinoma-associated fibroblasts; this promotes tumor progression through a variety of mechanisms in the tumor microenvironment. The role of autophagy in carcinoma-associated fibroblasts in tumor progression has not been elucidated. We aimed to clarify the significance of autophagy in fibroblasts, focusing on the TP53 status in co-cultured human colorectal cancer cell lines (TP53-wild-type colon cancer, HCT116; TP53-mutant colon cancer, HT29; fibroblast, CCD-18Co) in vitro. Autophagy in fibroblasts was significantly suppressed in association with ACTA2, CXCL12, TGFβ1, VEGFA, FGF2, and PDGFRA mRNA levels, when co-cultured with p53-deficient HCT116sh p53 cells. Exosomes isolated from the culture media of HCT116sh p53 cells significantly suppressed autophagy in fibroblasts via inhibition of ATG2B. Exosomes derived from TP53-mutant HT29 cells also suppressed autophagy in fibroblasts. miR-4534, extracted from the exosomes of HCT116sh p53 cells, suppressed ATG2B in fibroblasts. In conclusion, a loss of p53 function in colon cancer cells promotes the activation of surrounding fibroblasts through the suppression of autophagy. Exosomal miRNAs derived from cancer cells may play a pivotal role in the suppression of autophagy.

In situ delivery of biobutyrate by probiotic Escherichia coli for cancer therapy

Butyrate has a bioactive function to reduce carcinogenesis. To achieve targeted cancer therapy, this study developed bacterial cancer therapy (BCT) with butyrate as a payload. By metabolic engineering, Escherichia coli Nissle 1917 (EcN) was reprogrammed to synthesize butyrate (referred to as biobutyrate) and designated EcN-BUT. The adopted strategy includes construction of a synthetic pathway for biobutyrate and the rational design of central metabolism to increase the production of biobutyrate at the expense of acetate. With glucose, EcN-BUT produced primarily biobutyrate under the hypoxic condition. Furthermore, human colorectal cancer cell was administrated with the produced biobutyrate. It caused the cell cycle arrest at the G1 phase and induced the mitochondrial apoptosis pathway independent of p53. In the tumor-bearing mice, the injected EcN-BUT exhibited tumor-specific colonization and significantly reduced the tumor volume by 70%. Overall, this study opens a new avenue for BCT based on biobutyrate.

Adenine Inhibits the Invasive Potential of DLD-1 Human Colorectal Cancer Cell via the AMPK/FAK Axis

Tumor metastasis is a major cause of death of patients with colorectal cancer (CRC). Our previous findings show that adenine has antiproliferation activity against tumor cells. However, whether adenine reduces the invasiveness of DLD-1 and SW480 CRC cells has not been thoroughly explored. In this study, we aimed to explore the effects of adenine on the invasion potential of DLD-1 cells. Our findings showed that adenine at concentrations of ≤200 μM did not influence the cell viability of DLD-1 and SW480 CRC cells. By contrast, adenine reduced the migratory potential of the CRC cells. Moreover, it decreased the invasion capacity of the CRC cells in a dose-dependent manner. We further observed that adenine downregulated the protein levels of tissue plasminogen activator, matrix metalloproteinase-9, Snail, TWIST, and vimentin, but upregulated the tissue inhibitor of metalloproteinase-1 expression in DLD-1 cells. Adenine decreased the integrin αV level and reduced the activation of integrin-associated signaling components, including focal adhesion kinase (FAK), paxillin, and Src in DLD-1 cells. Further observations showed that adenine induced AMP-activated protein kinase (AMPK) activation and inhibited mTOR phosphorylation in DLD-1 cells. The knockdown of AMPK restored the reduced integrin αV level and FAK/paxillin/Src signaling inhibited by adenine in DLD-1 cells. Collectively, these findings reveal that adenine reduces the invasion potential of DLD-1 cells through the AMPK/integrin/FAK axis, suggesting that adenine may have anti-metastatic potential in CRC cells.

Inhibitory effect of an anti-prokineticin-1 antibody on liver metastasis in mice injected with human colorectal cancer cell lines

Controlling hematogenous metastases is an effective treatment strategy for colorectal cancer. Multidisciplinary treatment for colorectal cancer has made great strides, and molecularly-targeted drugs have greatly improved the prognosis of patients. However, currently accepted molecularly-targeted therapeutic agents require concomitant use with anticancer agents. Thus, new molecularly-targeted drugs need to be developed. The prokineticin family of angiogenic factors has the potential of becoming target molecules. Among them, prokineticin-1 (PROK1) is involved in the promotion of angiogenesis, tumor growth, and liver metastases in colorectal cancer. We manufactured our own anti-PROK1 antibody and verified its effect in inhibiting liver metastases and prolonging survival. The method involved creating liver metastasis model mice using human colorectal cancer cell lines. These mice were divided into anti-PROK1 antibody administration and control groups. Mice were treated intraperitoneally with antibodies or phosphate-buffered saline (control) every 3 days. The number of liver metastatic lesions and survival time of each group were compared. The number of metastatic lesions decreased, and survival time was significantly prolonged in the antibody-treated group. Furthermore, using microarray and immunostaining in both groups, we confirmed the effect of administering the anti-PROK1 antibody on the oxidation, reduction, and apoptotic processes, and cell division of tumors, and that alterations were suppressed in 72.1% of the genes examined. The expression of transforming growth factor-β (TGF-β), a tumor suppressor gene, was increased. The increased expression of TGF-β via PROK1 antibody administration may suppress the cancer cell proliferation ability, leading to liver metastasis suppression and prolonging the survival time of mice.