Walter Hundt MD, Presenter: Nothing to Disclose

Caitlin O Connell-Rodwell, Abstract Co-Author: Nothing to Disclose

Dirk Mayer, Abstract Co-Author: Nothing to Disclose

Samira Guccione PhD, Abstract Co-Author: Nothing to Disclose

Christopher H. Contag MD, PhD, Abstract Co-Author: Nothing to Disclose

Mark David Bednarski PhD, Abstract Co-Author: Nothing to Disclose

In vivo imaging of HSP70 expression in three different tumor lines exposed to different levels of thermal stress in correlation with diffusion weighted imaging.

Three tumor cell lines, M21, SCCVII and NIH3T3 were stable transfected with a plasmid, pHsp70A1-luc. M21 and NIH3T3 cells were injected into the flank of nude mice and the SCCVII cells into C3H/Km. To each treatment group 5 animals were assigned. At a size of 1500 mm3 the tumors were exposed to thermal stress (40ºC, 42ºC, 44ºC, 46ºC) for 20 min in a waterbath. MRI and bioluminescence imaging was performed prior to heat and at 8h, 48h, 96h and 192h after heat exposure. For MRI imaging (1.5 T GE Signa) a diffusion weighted steam sequence (TR=6000ms, TE=30ms, NEX=8, δ=9ms, Δ=170ms, b-values = 50, 250, 500, 750, 1000 (s/mm2)) was applied. Bioluminescence imaging of the tumors were performed by using a cooled CCD camera in a light tight box (IVIS, Xenogen Corp., Alameda, CA).

NIH3T3 tumors revealed the highest HSP70 expression after heat exposure. After 8 hours at 42°C a 368159%, at 44°C a 845001%, and at 46°C a 4610%, higher HSP70 expression could be found. The diffusion coefficient increased 16% at 42°C, 10% at 44° C and 6% at 46°C. M21 tumors showed after 8 hours at 42°C a 736%, higher, at 44°C a 18%, lower and at 46°C a 90% lower HSP70 expression compared to the baseline expression. The diffusion coefficient increased 0.6% at 42°C, 10% at 44° C and 11% at 46°C. SCCVII-tumors revealed the lowest heat tolerance. 8 hours after the exposure to 42ºC a 1208% higher, at 44°C a 16158% higher and at 46°C a 5.4% higher HSP70 expression increasemwas seen. The diffusion coefficient changed dramatically. The diffusion coefficient increased 6.9% at 42°C, 44% at 44° C and 34% at 46°C.

Different cell lines have a different HSP70 expression ability. In each tissue type diffusion imaging is different and depending on the temperature exposure. Diffusion imaging can be used as indirect parameter giving information about HSP70 expression changes depending of the tissue type.

Hundt, W, O Connell-Rodwell, C, Mayer, D, Guccione, S, Contag, C, Bednarski, M, In Vivo Imaging of HSP70 Expression in Correlation with Diffusion-weighted Imaging in Three Different Tumor Lines.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4419056.html