Purpose: Colorectal cancer patients diagnosed with stage I or II disease are not routinely offered adjuvant chemotherapy following resection of the primary tumor. However, up to 10% of stage I and 30% of stage II patients relapse within 5 years of surgery from recurrent or metastatic disease. The aim of this study was to determine if tumor-associated markers could detect disseminated malignant cells and so identify a subgroup of patients with early-stage colorectal cancer that were at risk of relapse. Experimental Design: We recruited consecutive patients undergoing curative resection for early-stage colorectal cancer. Immunobead reverse transcription-PCR of five tumor-associated markers (carcinoembryonic antigen, laminin g2, ephrin B4, matrilysin, and cytokeratin 20) was used to detect the presence of colon tumor cells in peripheral blood and within the peritoneal cavity of colon cancer patients perioperatively. Clinicopathologic variables were tested for their effect on survival outcomes in univariate analyses using the Kaplan-Meier method. A multivariate Cox proportional hazards regression analysis was done to determine whether detection of tumor cells was an independent prognostic marker for disease relapse. Results: Overall, 41 of 125 (32.8%) early-stage patients were positive for disseminated tumor cells. Patients who were marker positive for disseminated cells in post-resection lavage samples showed a significantly poorer prognosis (hazard ratio, 6.2; 95% confidence interval, 1.9-19.6; P = 0.002), and this was independent of other risk factors. Conclusion: The markers used in this study identified a subgroup of early-stage patients at increased risk of relapse post-resection for primary colorectal cancer.This method may be considered as a new diagnostic tool to improve the staging and management of colorectal cancer.
Colorectal cancer (CRC) is the second most prevalent and deadly cancer worldwide. Due to the mortality and morbidity associated with chemotherapeutic regimes, research is turning to natural product enhancement of the acute apoptotic response to genotoxic carcinogens (AARGC). Although Tyrian purple dye pigments and precursors from muricid molluscs are known for their anti-proliferative and proapoptotic activity, the chemoprotective properties of these edible molluscs has not been assessed. Enhancement of AARGC by oral administration of muricid extract (ME), containing a mixture of the cytotoxins tyrindoleninone and 6-bromoisatin, was assessed in an azoxymethane (AOM) rodent model. A dose-dependent increase in apoptotic index was observed in the distal colon, with a significant increase detected at an ME dose of 1.0 mg/g (p < 0.01). Proliferation (PCNA) index failed to vary significantly at this ME concentration, which confirms the ME-induced increase in apoptotic response to DNA alkylation. ME also appears to confer no major toxic side effects, as all mice consistently gained weight during the trial and colonic crypt height was maintained (p > 0.05) independent of ME dose. Although, this is the first example of AARGC enhancement by indole-based compounds, bioactive precursor degradation in simulated gastric fluid may prevent introduction of muricids as a chemopreventative food. Nevertheless, the protective effect of ME against CRC in vivo clearly substantiates further research into the chemopreventative efficacy of Muricidae natural products.
Marine molluscs from the family Muricidae are the source of a homeopathic remedy Murex, which is used to treat a range of conditions, including cancer. The aim of this study was to evaluate the in vitro bioactivity of egg mass extracts of the Australian muricid Dicathais orbita, in comparison to the Murex remedy, against human carcinoma and lymphoma cells. Liquid chromatography coupled with mass spectrometry (LC-MS) was used to characterize the chemical composition of the extracts and homeopathic remedy, focusing on biologically active brominated indoles. The MTS (tetrazolium salt) colorimetric assay was used to determine effects on cell viability, while necrosis and apoptosis induction were investigated using flow cytometry (propidium iodide and Annexin-V staining, resp.). Cells were treated with varying concentrations (1–0.01 mg/mL) of crude and semi-purified extracts or preparations (dilute 1 M and concentrated 4 mg/mL) from the Murex remedy (4 h). The Murex remedy showed little biological activity against the majority of cell lines tested. In contrast, the D. orbita egg extracts significantly decreased cell viability in the majority of carcinoma cell lines. Flow cytometry revealed these extracts induce necrosis in HT29 colorectal cancer cells, whereas apoptosis was induced in Jurkat cells. These findings highlight the biomedical potential of Muricidae extracts in the development of a natural therapy for the treatment of neoplastic tumors and lymphomas.
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