In vitro assessment of radiobiology of meningioma: A pilot study.

BACKGROUND: Meningioma are the second most common brain tumors in adults and can cause significant morbidity and mortality. The scarcity of in vitro and in vivo models represents the major obstacle to understand the molecular basis of meningioma tumorigenesis. The main aim of this study was to assess a method for radiobiology of meningioma cells colture by means of well-known meningioma lines. NEW METHOD: We carried out a protocol of cells culture for irradiation of meningioma cells. We used the immortalized cell lines IOMM-Lee and CH-157 to study their radiation-reponse by means of clonogenic assays and to evaluate their proliferation and apoptosis. We irradiated the cells with different total doses using two different linear accelerators. RESULTS: We observed a more radiation resistance of the IOMM-Lee than the CH-157. Indeed, the cellular death of CH-157 was obtained at a very low dose irradiation. Moreover, we showed a dose-response effect due to the early and late apoptosis, in fact the rate of apoptotic cells is greater than that of the necrotic cells at any dose of irradiation and at any time of analysis. COMPARISON WITH EXISTING METHODS: There is not a standardized method for radiobiology of meningioma experiments. CONCLUSIONS: Our method of cells culture appears suitable for radiosensitivity studies on meningioma. We can confirm that the response to radiotherapy depends not only on irradiation features, but also on tumor radiosensitivity.

Assessment of the homogeneous efficacy of carbon ions in the spread-out Bragg peak for human lung cancer cell lines.

PURPOSE: The aim of this study was to assess the radiosensitivities and homogeneous efficacy in the spread-out Bragg peak (SOBP) for lung cancer cell lines exposed to carbon ions. MATERIALS AND METHODS: The dose-dependent survival rates of seven cell lines exposed to carbon ions, fast neutrons, and photons were obtained using colony-forming assays in vitro. The relative biological effectiveness (RBE) of carbon ions and fast neutrons to photons was determined by comparing the doses at the 10% and 1% survival levels. RESULTS: The RBEs at 13, 40, 50, and 80 keV/microm were 1.20-1.29, 1.55-1.80, 1.57-2.00, and 1.69-2.58, respectively, at the 10% survival level. The RBE of 290 MeV carbon ions increased with increasing linear energy transfer. The biological dose (relative physical dose x RBE) distributions in the SOBP did not statistically differ at the proximal, mid, or distal points at the 10% (p = 0.945) and 1% (p = 0.211) survival levels, respectively; however, deviation of the biological dose at 10% and 1% survival were 3%-16% and 6%-24%, respectively. Furthermore, 290 MeV carbon ions at 80 keV/microm in the SOBP were nearly equivalent to 30 MeV fast neutrons. CONCLUSION: Our results demonstrate nearly homogeneous effectiveness in the SOBP, although we are aware of the deviation in some cell lines.

Assessment of DNA damage produced by 125I-triplex-forming oligonucleotides in cells.

PURPOSE: Triplex-forming oligodeoxyribonucleotides (TFOs) bind specifically to their target sequences by forming hydrogen bonds within the major groove of the target duplex. When labeled with Auger-electron-emitting radioisotopes, TFOs are able to damage the target gene in a process named antigene radiotherapy. We compared radiotoxicity and the amount of DNA damage produced within cultured cells by two 125I-labeled TFOs, one with a single target in the genome and another with multiple targets. MATERIALS AND METHODS: Radiotoxicity was measured by clonogenic assay while DNA damage was assessed by the number of histone gamma-H2AX foci formed at the sites of DNA double strand breaks (DSBs). RESULTS: The TFO with multiple nuclear targets was 1.7 fold more radiotoxic and produced on average 1.9 fold more gamma-H2AX foci per cell than the TFO with a single target. CONCLUSION: Since the two methods gave comparable results, measuring the number of gamma-H2AX foci per decay may be a useful procedure for the assessment of cytotoxic effects and the intranuclear localization of radionuclides when they produce DSBs.