Glioma stem-like cells (GSCs) are a subpopulation of cells in tumors that are believed to mediate self-renewal and relapse in glioblastoma (GBM), the most deadly form of primary brain cancer. In radiation oncology, hyperthermia is known to radiosensitize cells and it is re-emerging as a treatment option for patients with GBM. In this study, we investigated the mechanisms of hyperthermic radiosensitization in GSCs by a phospho-kinase array that revealed the survival kinase AKT as a critical sensitization determinant. GSCs treated with radiation alone exhibited increased AKT activation, but the addition of hyperthermia before radiotherapy reduced AKT activation and impaired GSC proliferation. Introduction of constitutively active AKT in GSCs compromised hyperthermic radiosensitization. Pharmacologic inhibition of PI3K further enhanced the radiosensitizing effects of hyperthermia. In a preclinical orthotopic transplant model of human GBM, thermoradiotherapy reduced pS6 levels, delayed tumor growth and extended animal survival. Together, our results offer a preclinical proof-of-concept for further evaluation of combined hyperthermia and radiation for GBM treatment.

Self-renewing colorectal cancer stem/progenitor cells (CSC) contribute to tumor maintenance and resistance to therapy. Therapeutic targeting of CSCs could improve treatment response and prolong patient survival. ONC201/TIC10 is a first-in-class antitumor agent that induces TRAIL pathway–mediated cell death in cancer cells without observed toxicity. We have previously described that ONC201/TIC10 exposure leads to transcriptional induction of the TRAIL gene via transcription factor Foxo3a, which is activated by dual inactivation of Akt and ERK. The Akt and ERK pathways serve as important targets in CSCs. Foxo3a is a key mediator of Akt and ERK-mediated CSC regulation. We hypothesized that the potent antitumor effect of ONC201/TIC10 in colorectal cancer involves targeting CSCs and bulk tumor cells. ONC201/TIC10 depletes CD133+, CD44+, and Aldefluor+ cells in vitro and in vivo. TIC10 significantly inhibits colonosphere formation of unsorted and sorted 5-fluorouracil–resistant CSCs. ONC201/TIC10 significantly reduces CSC-initiated xenograft tumor growth in mice and prevents the passage of these tumors. ONC201/TIC10 treatment also decreased xenograft tumor initiation and was superior to 5-fluorouracil treatment. Thus, ONC201/TIC10 inhibits CSC self-renewal in vitro and in vivo. ONC201/TIC10 inhibits Akt and ERK, consequently activating Foxo3a and significantly induces cell surface TRAIL and DR5 expression in both CSCs and non-CSCs. ONC201/TIC10-mediated anti-CSC effect is significantly blocked by the TRAIL sequestering antibody RIK-2. Overexpression of Akt, DR5 knockdown, and Foxo3a knockdown rescues ONC201/TIC10-mediated depletion of CD44+ cells and colonosphere inhibition. In conclusion, ONC201/TIC10 is a promising agent for colorectal cancer therapy that targets both non-CSCs and CSCs in an Akt–Foxo3a–TRAIL–dependent manner. Cancer Res; 75(7); 1–10. ©2015 AACR.

Self-renewing colorectal cancer stem/progenitor cells (CSCs) contribute to tumor maintenance and resistance to therapy. Therapeutic targeting of CSCs could improve treatment response and prolong patient survival. ONC201/TIC10 is a first-in-class anti-tumor agent that induces TRAIL pathway mediated cell death in cancer cells without observed toxicity. We have previously described that ONC201/TIC10 exposure leads to transcriptional induction of the TRAIL gene via transcription factor Foxo3a, which is activated by dual inactivation of Akt and ERK. The Akt and ERK pathways serve as important targets in CSCs. Foxo3a is a key mediator of Akt and ERK-mediated CSC regulation. We hypothesized that the potent anti-tumor effect of ONC201/TIC10 in colorectal cancer involves targeting CSCs and bulk tumor cells. ONC201/TIC10 depletes CD133(+), CD44(+) and Aldefluor(+) cells in vitro and in vivo. TIC10 significantly inhibits colonosphere formation of unsorted and sorted 5-Fluorouracil-resistant CSCs. ONC201/TIC10 significantly reduces CSC-initiated xenograft tumor growth in mice and prevents the passage of these tumors. ONC201/TIC10 treatment also decreased xenograft tumor initiation and was superior to 5-Fluorouracil treatment. Thus, ONC201/TIC10 inhibits CSC self-renewal in vitro and in vivo. ONC201/TIC10 inhibits Akt and ERK, consequently activating Foxo3a and significantly induces cell surface TRAIL and DR5 expression in both CSCs and non-CSCs. ONC201/TIC10-mediated anti-CSC effect is significantly blocked by the TRAIL sequestering antibody RIK-2. Overexpression of Akt, DR5 knockdown and Foxo3a knockdown rescues ONC201/TIC10-mediated depletion of CD44(+) cells and colonosphere inhibition. In conclusion, ONC201/TIC10 is a promising agent for colorectal cancer therapy that targets both non-CSCs and CSCs in an Akt-Foxo3a-TRAIL-dependent manner.

TP53 is the most frequently altered gene in head and neck squamous cell carcinoma (HNSCC), with mutations occurring in over two thirds of cases; however, the predictive response of these mutations to cisplatin-based therapy remains elusive. In the current study, we evaluate the ability of the Evolutionary Action score of TP53-coding variants (EAp53) to predict the impact of TP53 mutations on response to chemotherapy. The EAp53 approach clearly identifies a subset of high-risk TP53 mutations associated with decreased sensitivity to cisplatin both in vitro and in vivo in preclinical models of HNSCC. Furthermore, EAp53 can predict response to treatment and, more importantly, a survival benefit for a subset of head and neck cancer patients treated with platinum-based therapy. Prospective evaluation of this novel scoring system should enable more precise treatment selection for patients with HNSCC. Cancer Res; 75(7); 1–11. ©2015 AACR.

TP53 is the most frequently altered gene in head and neck squamous cell carcinoma (HNSCC) with mutations occurring in over two third of cases, however, the predictive response of these mutations to cisplatin based therapy remains elusive. In the current study, we evaluate the ability of the Evolutionary Action score of TP53 coding variants (EAp53) to predict the impact of TP53 mutations on response to chemotherapy. The EAp53 approach clearly identifies a subset of high risk TP53 mutations associated with decreased sensitivity to cisplatin both in vitro and in vivo in pre-clinical models of HNSCC. Furthermore, EAp53 can predict response to treatment and more importantly a survival benefit for a subset of head and neck cancer patients treated with platinum based therapy. Prospective evaluation of this novel scoring system should enable more precise treatment selection for patients with HNSCC.