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| IJCEM Copyright © 2008-All rights reserved. Published by e-Century Publishing Corporation, Madison, WI 53711 |
Int J Clin Exp Med 1(2),117-129;2008
Original Article
Alteration of Drug Sensitivity in Human Colon Cancer Cells after Exposure to Heat:
Implications for Liver Metastasis Therapy Using RFA and Chemotherapy
Ryouji Makizumi, Weng-Lang Yang, Randall P. Owen, Rohit R. Sharma and T. S. Ravikumar
Department of Surgery, North Shore University Hospital and Long Island Jewish Medical Center, The Feinstein Institute for Medical
Research, Manhasset, New York; Department of Surgery, Montefiore Medical Center, cAlbert Einstein College of Medicine, Bronx, New
York.
Received January 4, 2008; accepted January 17, 2008; available online February 28, 2008
Abstract: Radiofrequency ablation (RFA) is gaining popularity for treating colorectal liver metastases by inducing image guided tumor
hyperthermia. In order to reduce tumor recurrence, adjuvant therapies have been administered post-RFA. We hypothesized that tumor
cells escaping RFA cytotoxicity by being in the sublethal zones of tumor might develop differential behavior toward cytotoxic drugs. Here,
we used cultured human colorectal cancer cells to evaluate the interaction between heat treatment and chemotherapeutic agents.
Human colon cancer cell lines HT29 and HCT116 were subjected to temperatures of 42º to 50ºC for 15 min, in combination with 5-
fluorouracil, oxaliplatin, or irinotecan at different sequences. Cytotoxicity was determined by MTT assay. The cell cycle progression was
analyzed by flow cytometry with propidium iodide staining. The expression of several genes associated with drug sensitivity was
quantitated by real-time RT-PCR before and after heat treatment. Either heat treatment at 45ºC by simultaneous or pre-treatment with
three different chemotherapeutic agents didn’t affect the cytotoxicity of the combined treatment to HT29 and HCT116 cells, except for
irinotecan treatment in HCT116 cells. However, when pre-exposure to 45ºC, HCT116 cells, but not HT29 cells, developed resistance to
these three drugs. In an analysis of cell cycle profile after the drug followed heat treatment, a longer delay in cell cycle progression in
HCT116 cells was observed in comparison to HT29 cells. Furthermore, HCT116 and HT29 cells exhibited different expression profiles
of several drug-related genes in response to heat treatment at 45ºC. An observation of a differential response to the drug and heat
treatment sequences between two human colon cancer cell lines suggests that tumor heterogeneity and selection of
chemotherapeutic agents need to be under consideration in the clinical setting. (IJCEM801003).
Key Words: Hyperthermia; Chemotherapy; Colon cancer; Drug resistance; Cell cycle; Gene expression.
Full Text PDF
Address all correspondence to: T. S. Ravikumar, MD, Department of Surgery, North Shore University Hospital, 300 Community Drive,
Manhasset, NY 11030; Tel: (516) 562-2870; E-mail: tsravi@nshs.edu
Original Article
Alteration of Drug Sensitivity in Human Colon Cancer Cells after Exposure to Heat:
Implications for Liver Metastasis Therapy Using RFA and Chemotherapy
Ryouji Makizumi, Weng-Lang Yang, Randall P. Owen, Rohit R. Sharma and T. S. Ravikumar
Department of Surgery, North Shore University Hospital and Long Island Jewish Medical Center, The Feinstein Institute for Medical
Research, Manhasset, New York; Department of Surgery, Montefiore Medical Center, cAlbert Einstein College of Medicine, Bronx, New
York.
Received January 4, 2008; accepted January 17, 2008; available online February 28, 2008
Abstract: Radiofrequency ablation (RFA) is gaining popularity for treating colorectal liver metastases by inducing image guided tumor
hyperthermia. In order to reduce tumor recurrence, adjuvant therapies have been administered post-RFA. We hypothesized that tumor
cells escaping RFA cytotoxicity by being in the sublethal zones of tumor might develop differential behavior toward cytotoxic drugs. Here,
we used cultured human colorectal cancer cells to evaluate the interaction between heat treatment and chemotherapeutic agents.
Human colon cancer cell lines HT29 and HCT116 were subjected to temperatures of 42º to 50ºC for 15 min, in combination with 5-
fluorouracil, oxaliplatin, or irinotecan at different sequences. Cytotoxicity was determined by MTT assay. The cell cycle progression was
analyzed by flow cytometry with propidium iodide staining. The expression of several genes associated with drug sensitivity was
quantitated by real-time RT-PCR before and after heat treatment. Either heat treatment at 45ºC by simultaneous or pre-treatment with
three different chemotherapeutic agents didn’t affect the cytotoxicity of the combined treatment to HT29 and HCT116 cells, except for
irinotecan treatment in HCT116 cells. However, when pre-exposure to 45ºC, HCT116 cells, but not HT29 cells, developed resistance to
these three drugs. In an analysis of cell cycle profile after the drug followed heat treatment, a longer delay in cell cycle progression in
HCT116 cells was observed in comparison to HT29 cells. Furthermore, HCT116 and HT29 cells exhibited different expression profiles
of several drug-related genes in response to heat treatment at 45ºC. An observation of a differential response to the drug and heat
treatment sequences between two human colon cancer cell lines suggests that tumor heterogeneity and selection of
chemotherapeutic agents need to be under consideration in the clinical setting. (IJCEM801003).
Key Words: Hyperthermia; Chemotherapy; Colon cancer; Drug resistance; Cell cycle; Gene expression.
Full Text PDF
Address all correspondence to: T. S. Ravikumar, MD, Department of Surgery, North Shore University Hospital, 300 Community Drive,
Manhasset, NY 11030; Tel: (516) 562-2870; E-mail: tsravi@nshs.edu
