Assistant Professor University of North Carolina School of Medicine New York, New York, United States
Introduction: Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor and is ultimately fatal. Despite aggressive treatment, glioma rapidly recur, necessitating research on innovative therapies to improve prognosis and survival. One mechanism of interest is ferroptosis, a novel, non-apoptotic form of iron-dependent cell death. Previous research has demonstrated promise for ferroptosis-inducing drugs in the treatment of some cancers, including primary glioma. However, the efficacy of these drugs in recurrent glioma lines has yet to be determined. We aimed to generate a recurrent glioma line utilizing the well-characterized KR158b GBM line in C57 mice following primary resection and radiation treatment. We then investigated this line’s response to ferroptosis-inducing agents such as Ras-selective lethal (RSL3) with and these drugs’ synergism with cysteine-methionine depletion ex vivo.
Methods: KR158b cells were injected into 5mm x 5mm x 1mm cranial windows in C57 mice on day 0. Primary tumors were resected on post-injection day 14, and mice received 5 Gy radiation on days 18 and 20 (n = 2) or days 18, 20, and 22 (n = 3). The control group received no radiation (n = 2). Recurrent tumors were resected and plated with fibronectin coating media on day 30. Once confluent, ex-vivo recurrent tumors underwent puromycin selection (1 microgram/mL) for 7 days. Recurrent tumor cells were treated with RSL3 to determine sensitivity to ferroptosis in complete media as well as cysteine-methionine deficient (CMD) media.
Results: Recurrent tumors demonstrated resistance to ferroptosis following RSL3 treatment in normal media compared to the parent glioma line. The three-fraction glioma line demonstrated greater resistance to RSL3 compared to the two-fraction and control group. When treated with RSL3 in CMD media, sensitivity to ferroptosis was not increased over the complete-media response.
Conclusion : Radiation-treated recurrent glioma demonstrated resistance to ferroptosis-inducing agents compared to parent lines, with the three-fraction radiation group demonstrating the most resistance. This response was not enhanced when treated with RSL3 in CMD media.
