Project description:Understanding mechanisms underlying anti-tumor immunity is pivotal for improving immune-based cancer therapies. Here we demonstrate that growth of inoculated BRAF-mutant melanoma cells was inhibited, up to complete loss, in Siah2-/- mice.
Project description:Understanding the mechanisms underlying anti-tumor immunity is pivotal for improving immune-based cancer therapies. Here, we report that growth of BRAF-mutant melanoma cells is inhibited, up to complete rejection, in Siah2-/- mice. Growth-inhibited tumors exhibit increased numbers of intra-tumoral activated T cells and decreased expression of Ccl17, Ccl22, and Foxp3. Marked reduction in Treg proliferation and tumor infiltration coincide with G1 arrest in tumor infiltrated Siah2-/- Tregs in vivo or following T cell stimulation in culture, attributed to elevated expression of the cyclin-dependent kinase inhibitor p27, a Siah2 substrate. Growth of anti-PD-1 therapy resistant melanoma is effectively inhibited in Siah2-/- mice subjected to PD-1 blockade, indicating synergy between PD-1 blockade and Siah2 loss. Low SIAH2 and FOXP3 expression is identified in immune responsive human melanoma tumors. Overall, Siah2 regulation of Treg recruitment and cell cycle progression effectively controls melanoma development and Siah2 loss in the host sensitizes melanoma to anti-PD-1 therapy.
Project description:Understanding mechanisms underlying anti-tumor immunity is pivotal for improving immune-based cancer therapies. Here we demonstrate that growth of inoculated BRAF mutant melanoma cells was inhibited in Siah2-/- mice, up to a complete loss. Melanoma grown in Siah2-/- mice exhibited increased proinflammatory immune components, signified by enhanced intra-tumoral activated T cells, along with decreased expression of Ccl17 and Ccl22, and decreased Foxp3 expression. A marked reduction in Treg proliferation was associated with inhibition of Treg cell cycle progression. Correspondingly, G1 cell cycle arrest in Siah2-/- Tregs coincided with elevated expression of the cyclin dependent kinase inhibitor p27, a Siah2 substrate. Growth of PD1-unresponsive melanoma was effectively inhibited up to complete tumor rejection in Siah2-/- mice subjected to PD1 blockade, highlighting synergy between PD1 inhibition and Siah2 loss. Siah2 regulation of Treg recruitment and cell cycle progression effectively controls melanoma development and confers synthetic lethality when combined with anti-PD1 therapy.
Project description:The NanoString analysis of 784 genes expressed by 24 immune cell types in the melanoma cell at 11 days after injection were performed. The Nanostring analysis uncovered marked difference in key immune regulatory networks associated with T, DC, NC and macrophage function
Project description:Gene expression profiling was performed to identify Siah2-dependent changes in cells subjected to ER stress, hypoxia, and combined glucose/oxygen deprivation. To establish the magnitude of the Siah2 effect on the ER stress response, we have compared gene expression profiles of WT and Siah1a-/-::Siah2-/- mouse embryo fibroblasts (MEFs) that were subjected to glycosylation inhibitor tunicamycin (TM), thapsigargin (TG), glucose deprivation, or glucose/oxygen deprivation. Overall, this analysis confirmed changes associated with ER stress that had not previously been associated with Siah2 signaling, substantiating Siah2 as a key coordinator of ER stress through the ATF4 and sXbp1 pathways. WT and Siah1a/Siah2 KO MEF cells were treated with TM or TG for 6 h, or subjected for 12 h to oxygen deprivation, glucose deprivation or a combination of oxygen and glucose deprivation, in duplicate.
Project description:Gene expression profiling was performed to identify Siah2-dependent changes in cells subjected to ER stress, hypoxia, and combined glucose/oxygen deprivation. To establish the magnitude of the Siah2 effect on the ER stress response, we have compared gene expression profiles of WT and Siah1a-/-::Siah2-/- mouse embryo fibroblasts (MEFs) that were subjected to glycosylation inhibitor tunicamycin (TM), thapsigargin (TG), glucose deprivation, or glucose/oxygen deprivation. Overall, this analysis confirmed changes associated with ER stress that had not previously been associated with Siah2 signaling, substantiating Siah2 as a key coordinator of ER stress through the ATF4 and sXbp1 pathways.