The introduction of MAPK pathway inhibitors paved the road for significant advancements in the treatment of BRAF mutant (BRAFMUT) melanoma. However, even BRAF/MEK inhibitor combination therapy has failed to offer a curative treatment option, most likel...

miR-124 targets the androgen receptor (AR) transcript, acting as a tumor suppressor to broadly limit the growth of prostate cancer. In this study, we unraveled the mechanisms through which miR-124 acts in this setting. miR-124 inhibited proliferation o...

Tumors contain a heterogeneous myeloid fraction comprised of discrete MHC-IIhi and MHC-IIlo tumor-associated macrophage (TAM) subpopulations that originate from Ly6Chi monocytes. However, the mechanisms regulating the abundance and phenotype of distinc...

The treatment of glioblastoma (GBM) remains challenging in part due to the presence of stem-like tumor-propagating cells that are resistant to standard therapies consisting of radiation and temozolomide. Among the novel and targeted agents under evaluation for the treatment of GBM are BRAF/MAPK inhibitors, but their effects on tumor-propagating cells are unclear. Here, we characterized the behaviors of CD133+ tumor-propagating cells isolated from primary GBM cell lines. We show that CD133+ cells exhibited decreased sensitivity to the antiproliferative effects of BRAF/MAPK inhibition compared to CD133− cells. Furthermore, CD133+ cells exhibited an extended G2–M phase and increased polarized asymmetric cell divisions. At the molecular level, we observed that polo-like kinase (PLK) 1 activity was elevated in CD133+ cells, prompting our investigation of BRAF/PLK1 combination treatment effects in an orthotopic GBM xenograft model. Combined inhibition of BRAF and PLK1 resulted in significantly greater antiproliferative and proapoptotic effects beyond those achieved by monotherapy (P < 0.05). We propose that PLK1 activity controls a polarity checkpoint and compensates for BRAF/MAPK inhibition in CD133+ cells, suggesting the need for concurrent PLK1 inhibition to improve antitumor activity against a therapy-resistant cell compartment. Cancer Res; 75(24); 1–12. ©2015 AACR.

The rapidly advancing field of cancer immunotherapy is currently limited by the scarcity of noninvasive and quantitative technologies capable of monitoring the presence and abundance of CD8+ T cells and other immune cell subsets. In this study, we desc...