Schedule-dependent cytotoxicity of 5-fluorouracil and irinotecan in a colon cancer cell line

Association between mismatch repair gene and irinotecan-based chemotherapy in metastatic colon cancer

Mismatch repair (MMR) gene is closely related to the pathogenesis of colon cancer. This study aimed to evaluate the association between MMR status and efficacy of irinotecan-based chemotherapy. As a target of 5-FU, thymidylate synthase (TS) expression level might be influenced by irinotecan. Understanding whether this influence of TS is related with MMR status is helpful to the further exploration of the mechanism of irinotecan sensitivity in metastatic colon cancer with different MMR status. One hundred eighty-four patients with metastatic colon cancer receiving irinotecan-based chemotherapy for the first-line treatment were included. Correlations between MMR and clinicopathological characteristics and prognosis were determined. Two pairs of colon cancer cell lines (HCT-116-hMLH1(Vector) (deficient MMR, dMMR) versus HCT-116-hMLH1(+) (proficient MMR, pMMR); SW480-shRNA-hMLH1 (dMMR) versus SW480-shRNA-Control (pMMR)) were established by regulating MMR status. Sensitivity of these cell lines to irinotecan was determined by MTT assay. Regulation of TS by irinotecan was evaluated by western blotting and quantitative real-time PCR assay. dMMR accounted for 18.5 % and was related with proximal colon cancer (p = 0.005), poorly differentiated tumors (p = 0.018) and favorable efficacy with a higher disease control rate (DCR), a longer progression-free survival (PFS) and a trend of longer overall survival (OS). dMMR colon cancer cells were more sensitive to irinotecan. TS expression level was reduced more in dMMR cells after irinotecan treatment (p < 0.05). Our study favors an increased sensitivity of irinotecan in colon cancer with dMMR status. MMR status may be a predictive biomarker of response to irinotecan-based chemotherapy in metastatic colon cancer.

Clinical implications of CES2 RNA expression in neuroblastoma

BACKGROUND/PURPOSE

Human carboxylesterase 2 (CES2) is the key enzyme for metabolic activation of irinotecan (CPT-11). The aim was to evaluate the clinical implications of CES2 RNA expression in neuroblastoma cells.

METHODS

CES2 RNA expression was determined by real-time reverse transcription-polymerase chain reaction in five neuroblastoma cell lines and 42 clinical samples of untreated neuroblastoma. Sensitivity to CPT-11 was assessed by WST-8 colorimetric assays. Induction of apoptosis was evaluated by flow cytometry after CPT-11 exposure. Protein expression of CES2 was evaluated by Western blotting analysis. CES2 RNA expression in clinical samples was investigated for its associations with the clinicopathological characteristics.

RESULTS

CES2 RNA expression was observed in neuroblastoma cells, and its expression in neuroblastoma cell lines was positively correlated with sensitivity to CPT-11 and apoptosis after CPT-11 exposure in vitro. CES2 RNA expression was correlated with the protein levels of CES2 in vitro. CES2 RNA expression was significantly higher in patients with a characteristic related to advanced disease.

CONCLUSIONS

Our results suggest the potential of clinical application of CPT-11 in neuroblastoma treatment for patients with advanced disease.

Vitamin C Induces Apoptosis in Human Colon Cancer Cell Line, HCT-8 Via the Modulation of Calcium Influx in Endoplasmic Reticulum and the Dissociation of Bad from 14-3-3β

It has been reported that vitamin C plays an effective role in the treatment and prevention of cancer, but its specific mechanisms are still largely unknown. The incidence of colon cancer is now increasing in Korea. Therefore, we have examined here the effect of vitamin C on the induction of the apoptosis on colon cancer and its related mechanisms. We have found that remarkable increase of the apoptosis and the calcium influx in endoplasmic reticulum (ER) in human colon cancer cell line, HCT-8. However, vitamin C-induced apoptosis was effectively inhibited by the pre-treatment of BAPTA-AM (1,2-bis(o-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid), which is well-known as a calcium specific chelator. During the apoptosis, we found the increase of the translocation of Bad to mitochondria from cytosol, after releasing from 14-3-3β. In this process, the expression of Bax, a well-known pro-apoptotic protein, was also increased. Taken together, vitamin C induces apoptosis of colon cancer cell line, HCT-8 through the increase of 1) the calcium influx in endoplasmic reticulum (ER), 2) the translocation of Bad to mitochondria, and 3) the expression of Bax.

Therapeutic strategy in unresectable metastatic colorectal cancer

While surgery is the cornerstone treatment for early-stage colorectal cancer, chemotherapy is the first treatment option for metastatic disease when tumor lesions are frequently not fully resectable at presentation. Mortality from colon cancer has decreased over the past 30 years, but there is still a huge heterogeneity in survival rates that can be mainly explained by patient and tumor characteristics, host response factors, and treatment modalities. The management of unresectable metastatic colorectal cancer is a global treatment strategy, which applies several lines of therapy, salvage surgery, maintenance, and treatment-free intervals. The individualization of cancer treatment is based on the evaluation of prognostic factors for survival (serum lactate dehydrogenase level, performance status), and predictive factors for treatment efficacy [Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation status]. The available treatment modalities for metastatic colorectal cancer are chemotherapy (fluoropyrimidine, oxaliplatin, irinotecan), anti-angiogenic agents (e.g. bevacizumab), and anti-epidermal growth factor agents (cetuximab, panitumumab). The increasing number of active compounds dictates the strategy of trials evaluating these treatments either in combination or sequentially. Alternative outcomes that can be measured earlier than overall survival are needed to shorten the duration and reduce the size and cost of clinical trials.