CPT-11 Converting Enzyme from Rat Serum: Purification and Some Properties.

Tsuji, Tatsuya; Kaneda, Norimasa; Kado, Kunio; Yokokura, Teruo; Yoshimoto, Tadashi; Tsuru, Daisuke

doi:10.1248/bpb1978.14.341

Cited by 126 publications

(50 citation statements)

References 12 publications

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“…CE activities in human tumours vary widely, as reported in 18 different tumour types: interestingly, SCLC tumour tissues were found among those displaying the highest CE activity . Determination of CE activity may pose some technical problems for application in human tumours, as a study in rats and mice showed that endogenous carboxylesterase enzymes are present in several normal tissues, including plasma, intestinal mucosa and liver (Tsuji et al, 1991;Jansen et al, 1997). In our study, however, only a low CE activity was found in human serum compared with that found in the human lung cancer cell lines.…”

Section: Discussioncontrasting

confidence: 79%

“…Carboxylesterase (CE) activity was assessed in all cell lines, culture medium and blood of healthy volunteers by measuring the hydrolysis of pNPA to para-nitrophenol catalysed by CE, as described by Tsuji et al (1991). Briefly, cells were harvested, counted and washed twice with cold phosphate-buffered saline (PBS); cell pellets were then solubilized in 20 mm cold Tris-HCl, pH 7.5, and placed on ice for 1 h. After centrifugation at 14 000 r.p.m.…”

Section: Carboxylesterase Activitymentioning

confidence: 99%

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Determinants of CPT-11 and SN-38 activities in human lung cancer cells

Ark-Otte

Kedde²,

Vijgh³

et al. 1998

Br J Cancer

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Summary Irinotecan (CPT-11) is a semisynthetic camptothecin derivative with a broad spectrum of anti-tumour activity. Carboxylesterase (CE) catalyses the conversion of CPT-11 to , the active form of CPT-11. The antiproliferative effects of CPT-11 and SN-38, CE-activity and topoisomerase protein expression were investigated in five human small-cell lung cancer (SCLC) cell lines and four human non-small-cell lung cancer (NSCLC) cell lines. Antiproliferative activity, expressed as IC50 values, was determined using the MTT assay. CPT-11 was significantly more active in SCLC than in NSCLC cell lines (P = 0.0036), whereas no significant difference between histological types was observed with SN-38. A significant correlation (r2 = 0.52, P = 0.028) was observed between CE activity and chemosensitivity to CPT-11 but not to SN-38, and significantly higher CE activity was observed in SCLC compared with NSCLC cell lines (P = 0.025). Western blotting experiments showed topoisomerase protein expressions within a factor of 2, and a granular nuclear staining was detectable in all cell lines by immunocytochemistry of cytospins. No correlation was observed between protein expression and sensitivity to CPT-11 or SN-38. Cellular and medium concentrations of CPT-11 and SN-38 were measured by high-performance liquid chromatography (HPLC) in one SCLC cell line with high CE activity and high sensitivity to CPT-11, and one NSCLC cell line with low sensitivity to CPT-1i1 and CE activity. Intracellular concentrations of CPT-11 and SN-38 were higher in the SCLC cell line, and this was associated with an increase in cellular uptake of CPT-11 compared with the medium, and an increased intracellular formation of SN-38. In conclusion, CE activity appears to be associated with higher sensitivity to CPT-1i1 in human lung cancer cell lines and may partly explain the difference in the in vitro sensitivity to CPT-11 between SCLC and NSCLC cells. The assessment of CE activity in clinical material of lung cancer patients undergoing treatment with CPT-11 may be warranted. However, other mechanisms may influence sensitivity to CPT-11, possibly including drug transport.

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Section: Discussioncontrasting

confidence: 79%

Section: Carboxylesterase Activitymentioning

confidence: 99%

Determinants of CPT-11 and SN-38 activities in human lung cancer cells

Ark-Otte

Kedde²,

Vijgh³

et al. 1998

Br J Cancer

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“…In fact, the low efficiency of carboxylesterases seems to be a general feature of the human enzymes, and the interspecies comparison of the carboxylesterases with a panel of substrates, demonstrated that the human enzymes were among the less efficient (Hosokawa et al, 1990). However, a specific CPT-CE was isolated from rat serum (Tsuji et al, 1991). These authors demonstrated that the CPT-CE exhibited different enzymatic properties compared to the other carboxylesterases and that the Km was different between p-NPA and CPT-11.…”

mentioning

confidence: 99%

“…These authors demonstrated that the CPT-CE exhibited different enzymatic properties compared to the other carboxylesterases and that the Km was different between p-NPA and CPT-11. The conversion of CPT-11 into SN-38 has been studied in a wide variety of tissues, cell lines and purified enzyme preparations in vitro (Jansen et al, 1997;Kawato et al, 1991;Ogasawara et al, 1995;Rivory et al, 1996;Satoh et al, 1994;Slatter et al, 1997;Tsuji et al, 1991;van Ark-Otte et al, 1998). The sensitivity of proliferating tissues or cell lines to cytotoxic effects of CPT-11 may be related to their carboxylesterase levels (Kawato et al, 1991;Ogasawara et al, 1995).…”

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CPT-11 converting carboxylesterase and topoisomerase I activities in tumour and normal colon and liver tissues

et al. 1999

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Summary CPT-11 is a prodrug activated by carboxylesterases to the active metabolite SN-38 which is a potent inhibitor of topoisomerase I. CPT-11 is of clinical interest in the treatment of colorectal cancer. We evaluated the activities of CPT-11 converting carboxylesterase (CPT-CE) and topoisomerase I (topo I) in 53 colorectal tumours, in eight liver metastases and in normal tissue adjacent to the tumours. Both CPT-CE and topo I activities were widely variable in the malignant and the normal tissue of patients with colorectal carcinomas. CPT-CE was only two to threefold lower in primary tumours compared to normal liver, suggesting that a local conversion to SN-38 might occur in tumour cells. CPT-CE was similar in liver and in normal colon tissues. Levels of topo I in tumour ranged from 580 to 84 900 U mg protein -1 and was above 40 000 U mg protein -1 in 11 of 53 patients. Similarly, a very high ratio (> 5) between tumour and normal tissues were observed in 12 of 53 patients. An inverse correlation was observed between the topo I activity and the clinical stage of disease. Clinical studies are in progress in our institution to explore a possible relationship between CPT-CE and topo I activities in tumour cells and the response to CPT-11-based chemotherapy in patients with colorectal cancer.

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“…(1-piperidino)-1-piperidino] carbonyloxycamptothecin) is an anticancer agent that is approved for first-line treatment of metastatic colon cancer. In order to be fully active, CPT-11 needs to be activated into the active compound by carboxylesterase (CE) enzymes (Tsuji et al, 1991;Satoh et al, 1994). Although SN-38 is detected in the plasma of cancer patients only minutes after administration of CPT-11 (Gupta et al, 1997), 90 -95% of the prodrug is not converted to SN-38 (Rivory et al, 1997).…”

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Adenoviral vector-mediated expression of a gene encoding secreted, EpCAM-targeted carboxylesterase-2 sensitises colon cancer spheroids to CPT-11

et al. 2005

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CPT-11 (irinotecan or 7-ethyl-10[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin) is an anticancer agent in use for the treatment of colon cancer. In order to be fully active, CPT-11 needs to be converted into by the enzyme carboxylesterase (CE). In humans, only a minority of CPT-11 is converted to SN-38. To increase the antitumour effect of CPT-11 by gene-directed enzyme prodrug therapy, we constructed a replication-deficient adenoviral vector Ad.C28-sCE2 containing a fusion gene encoding a secreted form of human liver CE2 targeted to the surface antigen epithelial cell adhesion molecule (EpCAM) that is highly expressed on most colon carcinoma cells. By targeting CE2 to EpCAM, the enzyme should accumulate specifically in tumours and leakage into the circulation should be minimised. Ad.C28-sCE2-transduced colon carcinoma cells expressed and secreted active CE that bound specifically to EpCAM-expressing cells. In sections of three-dimensional colon carcinoma spheroids transduced with Ad.C28-sCE2, it was shown that C28-sCE2 was capable of binding untransduced cells. Most importantly, treatment of these spheroids with nontoxic concentrations of CPT-11 resulted in growth inhibition comparable to treatment with SN-38. Therefore, Ad.C28-sCE2 holds promise in gene therapy approaches for the treatment of colon carcinoma.

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CPT-11 Converting Enzyme from Rat Serum: Purification and Some Properties.

Cited by 126 publications

References 12 publications

Determinants of CPT-11 and SN-38 activities in human lung cancer cells

Determinants of CPT-11 and SN-38 activities in human lung cancer cells

CPT-11 converting carboxylesterase and topoisomerase I activities in tumour and normal colon and liver tissues

Adenoviral vector-mediated expression of a gene encoding secreted, EpCAM-targeted carboxylesterase-2 sensitises colon cancer spheroids to CPT-11

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