Enhanced apoptotic reaction correlates with suppressed tumor glucose utilization after cytotoxic chemotherapy: use of 99mTc-Annexin V, 18F-FDG, and histologic evaluation.
Cancer chemotherapy enhances the apoptosis, whereas apoptosis is a suicidal mechanism requiring energy. We determined the relationship between apoptosis and glucose utilization during cancer chemotherapy using (99m)Tc-annexin V ((99m)Tc-annexin A5) and (18)F-FDG and compared their uptake with histologic findings in a rat tumor model.


METHODS
Allogenic hepatoma cells (KDH-8) were inoculated into the left calf muscle of male Wistar rats (WKA). Eleven days after the inoculation, the rats were randomly divided into 3 groups: The first group (n = 7) received a single dose of gemcitabine (90 mg/kg, intravenously), the second group (n = 8) received cyclophosphamide (150 mg/kg, intraperitoneally), and the third group (n = 7) was untreated and served as the control group. We injected (99m)Tc-annexin V 48 h after the chemotherapy and then injected (18)F-FDG to all rats 1 h before sacrifice. Six hours after (99m)Tc-annexin V injection, the rats were sacrificed and the organs, including the tumor, were removed and radioactivity was counted. The radioactivities of (18)F and (99m)Tc in the organs were determined using normalization by tissue weight. Histologic evaluation by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) method and the immunostaining of glucose transporter-1 (GLUT-1) were also performed to obtain the indices of apoptosis and glucose utilization, respectively. The rate of positively stained cells was calculated and analyzed statistically.


RESULTS
After chemotherapy using gemcitabine and cyclophosphamide, the (99m)Tc-annexin V uptake (percentage injected dose per gram x kg [(%ID/g) x kg]; mean +/- SD) in tumor increased significantly (0.062 +/- 0.012 (%ID/g) x kg in the gemcitabine-treated group and 0.050 +/- 0.012 (%ID/g) x kg in the cyclophosphamide group vs. 0.031 +/- 0.005 (%ID/g) x kg in the control group; P < 0.01). In contrast, the (18)F-FDG in tumor decreased significantly (0.483 +/- 0.118 (%ID/g) x kg in the gemcitabine group and 0.583 +/- 0.142 (%ID/g) x kg in the cyclophosphamide group) compared with that in the control group (0.743 +/- 0.084 (%ID/g) x kg; P < 0.01). In addition, (18)F-FDG uptake in tumor negatively correlated with (99m)Tc-annexin V uptake (r = -0.75; P < 0.01). In the gemcitabine and cyclophosphamide groups, the rate of TUNEL positively stained cells was significantly higher than that in the control group (10.2% +/- 1.7% and 8.0% +/- 1.5% vs. 5.2% +/- 1.5%; P < 0.01), whereas the GLUT-1 expression level showed no definite changes in histologic analyses.


CONCLUSIONS
These data indicate that an enhanced apoptotic reaction correlated with suppressed tumor glucose utilization after cytotoxic chemotherapy as determined using radiotracers and histologic evaluation. The increase in (99m)Tc-annexin V and the decrease in (18)F-FDG in tumor can be useful markers for predicting therapeutic outcomes and for prognosis at the early stage of chemotherapy.
Takei
Toshiki
T
Department of Nuclear Medicine, Graduate School of Medicine, Hokkaido University, Kita 15 Nishi 7, Kita-ku, Sapporo 060-8638, Japan.
Kuge
Yuji
Y
Zhao
Songji
S
Sato
Masayuki
M
Strauss
H William
HW
Blankenberg
Francis G
FG
Tait
Jonathan F
JF
Tamaki
Nagara
N
D000818:Animals; D017304:Annexin A5 / Q000493:pharmacokinetics; D000970:Antineoplastic Agents / Q000008:administration & dosage; D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D003520:Cyclophosphamide / Q000008:administration & dosage*; D003841:Deoxycytidine / Q000008:administration & dosage* / Q000031:analogs & derivatives*; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D005947:Glucose / Q000378:metabolism*; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D008297:Male; D008657:Metabolic Clearance Rate / Q000187:drug effects; D009928:Organ Specificity; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics; D011379:Prognosis; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D051381:Rats; D017208:Rats, Wistar; D013223:Statistics as Topic; D014018:Tissue Distribution / Q000187:drug effects; D000093542:Gemcitabine
D017304:Annexin A5; D000970:Antineoplastic Agents; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C117287:technetium Tc 99m HYNIC annexin V; D003841:Deoxycytidine; D019788:Fluorodeoxyglucose F18; D003520:Cyclophosphamide; D005947:Glucose; D000093542:Gemcitabine