• Astragalus saponins induce growth inhibition and apoptosis in human colon cancer cells and tumor xenograft.

      Tin, Mandy; Cho, Chi-Hin; Chan, Kelvin C.; James, Anthony; Ko, Joshua (Oxford Journals, 2007)
      Astragalus memebranaceus is used as immunomodulating agent in treating immunodeficiency diseases and to alleviate the adverse effects of chemotherapeutic drugs. In recent years, it has been proposed that Astragalus may possess anti-tumorigenic potential in certain cancer cell types. In this study, the anti-carcinogenic effects of Astragalus saponin extract were investigated in HT-29 human colon cancer cells and tumor xenograft. Our findings have shown that Astragalus saponins (AST) inhibit cell proliferation through accumulation in S phase and G2/M arrest, with concomitant suppression of p21 expression and inhibition of cyclin-dependent kinase activity. Besides, AST promotes apoptosis in HT-29 cells through caspase 3 activation and poly(ADP-ribose) polymerase cleavage, which is indicated by DNA fragmentation and nuclear chromatin condensation. Nevertheless, we also demonstrate the anti-tumorigenic effects of AST in vivo, of which the reduction of tumor volume as well as pro-apoptotic and anti-proliferative effects in HT-29 nude mice xenograft are comparable with that produced by the conventional chemotherapeutic drug 5-fluorouracil (5-FU). In addition, the side effects (body weight drop and mortality) associated with the drug combo 5-FU and oxaliplatin are not induced by AST. These results indicate that AST could be an effective chemotherapeutic agent in colon cancer treatment, which might also be used as an adjuvant in combination with other orthodox chemotherapeutic drugs to reduce the side effects of the latter compounds.
    • In vitro evaluation of cancer-specific NF-kappaB-CEA enhancer-promoter system for 5-fluorouracil prodrug gene therapy in colon cancer cell lines.

      Guo, X.; Evans, T.R.J.; Somanath, S.; Armesilla, Angel; Darling, John L.; Schatzlein, A.; Cassidy, James; Wang, Weiguang (Nature Publishing Group, 2007)
      Nuclear factor-kappa B (NF-kappaB) is a transcription factor with high transcriptional activity in cancer cells. In this study, we developed a novel enhancer-promoter system, kappaB4-CEA205, in which the basal carcinoembryonic antigen (CEA) promoter sequence (CEA205) was placed downstream of the four tandem-linked NF-kappaB DNA-binding sites (kappaB4). In combination with a kappaB4 enhancer, the transcriptional activity of the CEA promoter was significantly enhanced (three- to eight-fold) in cancer cell lines but not in normal cells. In cancer cell lines, the transcriptional activity of kappaB4-CEA205 was comparable with that of the SV40 promoter. We also constructed vectors in which the thymidine phosphorylase (TP) cDNA was under the control of CEA205, kappaB4, kappaB4-CEA205 and CMV promoters, respectively. TP protein and enzyme activity were detected at comparable levels in kappaB4-CEA205- and CMV-driven TP cDNA-transfected cancer cell lines (H630 and RKO). The kappaB4-TP and CEA205-TP-transfected cell lines, respectively, only demonstrated negligible and low levels of TP protein and enzyme activity. Both CMV- and kappaB4-CEA205-driven TP cDNA transiently transfected cells were 8- to 10-fold sensitised to 5-fluorouracil (5-FU) prodrug, 5'-deoxy-5-fluorouradine (5'-DFUR), in contrast to only 1.5- to 2-fold sensitised by the kappaB4- and CEA205-driven TP cDNA-transfected cells. The bystander killing effect of CMV- and kappaB4-CEA205-driven TP cDNA-transfected cells was comparable. This is the first report that indicates that the NF-kappaB DNA-binding site could be used as a novel cancer-specific enhancer to improve cancer-specific promoter activity in gene-directed enzyme prodrug therapy.
    • Validation of epigenetic markers to identify colitis associated cancer: Results of module 1 of the ENDCAP-C study

      Beggs, Andrew D; Mehta, Samir; Deeks, Jonathan J; James, Jonathan D; Caldwell, Germaine M; Dilworth, Mark P; Stockton, Joanne D; Blakeway, Daniel; Pestinger, Valerie; Vince, Alexandra; et al. (Elsevier, 2018-11-22)
      BACKGROUND:Chronic inflammation caused by ulcerative colitis (UC) causes a pro-neoplastic drive in the inflamed colon, leading to a markedly greater risk of invasive malignancy compared to the general population. Despite surveillance protocols, 50% of cases proceed to cancer before neoplasia is detected. The Enhanced Neoplasia Detection and Cancer Prevention in Chronic Colitis (ENDCaP-C) trial is an observational multi-centre test accuracy study to ascertain the role of molecular markers in improving the detection of dysplasia. We aimed to validate previously identified biomarkers of neoplasia in a retrospective cohort and create predictive models for later validation in a prospective cohort. METHODS:A retrospective analysis using bisulphite pyrosequencing of an 11 marker panel (SFRP1, SFRP2, SRP4, SRP5, WIF1, TUBB6, SOX7, APC1A, APC2, MINT1, RUNX3) in samples from 35 patients with cancer, 78 with dysplasia and 343 without neoplasia undergoing surveillance for UC associated neoplasia across 6 medical centres. Predictive models for UC associated cancer/dysplasia were created in the setting of neoplastic and non-neoplastic mucosa. FINDINGS:For neoplastic mucosa a five marker panel (SFRP2, SFRP4, WIF1, APC1A, APC2) was accurate in detecting pre-cancerous and invasive neoplasia (AUC = 0.83; 95% CI: 0.79, 0.88), and dysplasia (AUC = 0.88; (0.84, 0.91). For non-neoplastic mucosa a four marker panel (APC1A, SFRP4, SFRP5, SOX7) had modest accuracy (AUC = 0.68; 95% CI: 0.62,0.73) in predicting associated bowel neoplasia through the methylation signature of distant non-neoplastic colonic mucosa. INTERPRETATION:This multiplex methylation marker panel is accurate in the detection of ulcerative colitis associated dysplasia and neoplasia and is currently being validated in a prospective clinical trial. FUNDING:The ENDCAP-C study was funded by the National Institute for Health Research Efficacy and Mechanism Evaluation (EME) Programme (11/100/29).