PT  - JOURNAL ARTICLE
AU  - Sharma, Rituka I.
AU  - Smith, Tim A.D.
TI  - Colorectal Tumor Cells Treated with 5-FU, Oxaliplatin, Irinotecan, and Cetuximab Exhibit Changes in <sup>18</sup>F-FDG Incorporation Corresponding to Hexokinase Activity and Glucose Transport
AID  - 10.2967/jnumed.107.047886
DP  - 2008 Aug 01
TA  - Journal of Nuclear Medicine
PG  - 1386--1394
VI  - 49
IP  - 8
4099  - http://jnm.snmjournals.org/content/49/8/1386.short
4100  - http://jnm.snmjournals.org/content/49/8/1386.full
SO  - J Nucl Med2008 Aug 01; 49
AB  - The purpose of this study was to determine therapy-induced changes in 18F-FDG incorporation at the colorectal tumor cell level in response to conventional and novel chemotherapy agents and examine how these changes relate to factors involved in 18F-FDG incorporation. Methods: SW620 cells were treated with inhibitory concentration of 50% (IC50) doses (determined by MTT) of 5-fluorouracil (5-FU), oxaliplatin, and irinotecan; HCT-8 cells were treated with IC50 doses of irinotecan, cetuximab, and irinotecan plus cetuximab. 18F-FDG incorporation, glucose transport, hexokinase (HK) activity, adenosine triphosphate (ATP) content, annexin V binding, and cell cycle distribution were determined after 24-, 48-, and 72-h treatments. Eight-hour treatments with and without subsequent incubation in drug-free medium were also examined. A clonogenic assay was used to determine the tumor-forming ability of treated cells. Results: Apoptosis was evident in SW620 cells, especially after treatment with irinotecan and 5-FU. 18F-FDG incorporation was increased in SW620 cells after 24- or 48-h treatments with some agents and in HCT-8 cells after irinotecan treatment but was decreased in all 72-h treatments or cell-line combinations including cetuximab. Treatment of SW620 cells for 8 h followed by 64 h in drug-free medium also resulted in decreased 18F-FDG incorporation. Decreased 18F-FDG incorporation broadly corresponded to glucose transport in HCT-8 cells and to HK activity in SW620 cells. Inhibition of glucose transport decreased 18F-FDG incorporation into HCT-8 but not into SW620 cells. ATP levels were decreased by oxaliplatin treatment and increased at 48 or 72 h after irinotecan treatment. Conclusion: 18F-FDG incorporation is modulated by therapy-induced changes in both glucose transport and HK activity depending on the tumor cell. Colorectal cells treated with IC50 doses of cetuximab also exhibit decreased 18F-FDG.