Katja Lindel, Presenter: Nothing to Disclose

Marco Vercruysse, Abstract Co-Author: Nothing to Disclose

Stefan Rieken, Abstract Co-Author: Nothing to Disclose

Sigrid Daffinger, Abstract Co-Author: Nothing to Disclose

Juergen Debus MD, PhD, Abstract Co-Author: Nothing to Disclose

Purpose/Objective(s): To compare the effect of photon and carbon-ion radiation on four cell lines with different HPV-status regarding cell cycle regulation and HPV associated protein expression. Hypothesis is that carbon ion radiation might overcome radiation resistance of HPV-negative or HPV-integrated cells.Materials/Methods: W12 cell line was derived from a low grade cervical lesion by Stanley MA et al. 1989, and is unique among HPV16-containing cell lines in carrying its HPV 16 genome as a multicopy episome. W12 cells contain episomal HPV 16 genomes, whereas S12 cells, which derived from the W12 line, contain HPV DNA as integrated copies. Caski cells have their origin in epidermoid cell cervical cancer and are reported to contain an HPV 16 genome as well as sequences related to HPV-18. C33A is a HPV-negative human cervical cancer derived cell line. Cell cycle analyses were performed using flow cytometry (PI staining) 24 h and 48 h after RT with 2 and 7 Gy using photon RT and 2 GyE and 7 GyE carbon ion RT(C12). Expression of pRb and p53 after irradiation with 2 and 7 Gy were analyzed by flow cytometry using intracellular staining comparing the mean fluorescence of 10000 gated cells.Results: C33A cells (HPV-negative) showed a minimal enhanced expression of pRB after RT with photons or C12 (0 Gy=1.0, 2 Gy=1.09, 7 Gy=1. 4, 2 GyE= 1.3, 7 GyE=1.1). There was no effect of photon or C12 irradiation on p53 expression in C33A cells. Caski cells (HPV16/18 positive) showed increased expression after photon RT (2 Gy=1.3, 7 Gy=1.7). Irradiation with C12 induced a strong increase of pRb expression (2 GyE=7.7, 7 GyE=8.3). There was a minimal change of p53 expression after RT (2 Gy=1.3; 7 Gy=1.2, 2 GyE=1.6, 7 GyE=1.5). S12 cells (HPV 16 integrated) showed a decrease of pRB expression after RT with photons (2 Gy=0.47, 7 Gy=0.38). Irradiation with C12 enhanced the expression of pRb positive cells (2 GyE= 1.8,7 GyE=1.94), but showed no significant expression of p53 in the control group. W12 cells (HPV 16 episomal) showed no change of pRb expression in the control group or after RT. C12 RT induced an increase of pRb expression (2 GyE=1.5, 7 Gy=2.9). There was no significant change of p53 expression in W12 and S12 cells after RT. C12-RT showed no effect on cell cycle distribution in W12/S12 and C33A cells. 48 h after irradiation with 7 Gy photons in C33A cells and 24 h after RT in S12 cells a G2/M-block was induced.Conclusions: The effect of carbon-ion-RT on protein expression seems to be dependent on HPV-status and type of protein with no effect on p53 or on HPV-negative cells, but a strong effect on pRb expression in HPV-positive cells. The converse effect of carbon-ion-RT compared to photon-RT on HPV positive cell with integrated HPV regarding pRb expression indicates that carbon-ion therapy might overcome HPV-integration induced radioresistance.

Lindel, K, Vercruysse, M, Rieken, S, Daffinger, S, Debus, J, Carbon-ion and Photon Radiation Effects on Human Papilloma Virus—Positive and—Negative Cervical Carcinoma Cells.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14043397.html