RNA sequencing of control and DAC-treated CT26 cells.
Ontology highlight
ABSTRACT: PD-1 blockade has demonstrated impressive clinical outcomes in colorectal cancers that have high microsatellite instability. However, the therapeutic efficacy for patients with tumors with low microsatellite instability or stable microsatellites needs further improvement. Here, we have demonstrated that low-dose decitabine could increase the expression of immune-related genes such as major histocompatibility complex genes and cytokine-related genes as well as the number of lymphocytes at the tumor site in CT26 colorectal cancer-bearing mice. A more significant inhibition of tumor growth and a prolongation of survival were observed in the CT26 mouse model after treatment with a combination of PD-1 blockade and decitabine than in mice treated with decitabine or PD-1 blockade alone. The anti-tumor effect of the PD-1 blockade was enhanced by low-dose decitabine. The results of RNA sequencing and whole-genome bisulfite sequencing of decitabine-treated CT26 cells and tumor samples with microsatellite stability from the patient tumor-derived xenograft model have shown that many immune-related genes, including antigen processing and antigen-presenting genes, were upregulated, whereas the promoter demethylation was downregulated after decitabine exposure. Therefore, decitabine-based tumor microenvironment re-modulation could improve the effect of the PD-1 blockade. The application of decitabine in PD-1 blockade-based immunotherapy may elicit more potent immune responses, which can provide clinical benefits to the colorectal cancer patients with low microsatellite instability or stable microsatellites.
Project description:PD-1 blockade has demonstrated impressive clinical outcomes in colorectal cancers that have high microsatellite instability. However, the therapeutic efficacy for patients with tumors with low microsatellite instability or stable microsatellites needs further improvement. Here, we have demonstrated that low-dose decitabine could increase the expression of immune-related genes such as major histocompatibility complex genes and cytokine-related genes as well as the number of lymphocytes at the tumor site in CT26 colorectal cancer-bearing mice. A more significant inhibition of tumor growth and a prolongation of survival were observed in the CT26 mouse model after treatment with a combination of PD-1 blockade and decitabine than in mice treated with decitabine or PD-1 blockade alone. The anti-tumor effect of the PD-1 blockade was enhanced by low-dose decitabine. The results of RNA sequencing and whole-genome bisulfite sequencing of decitabine-treated CT26 cells and tumor samples with microsatellite stability from the patient tumor-derived xenograft model have shown that many immune-related genes, including antigen processing and antigen-presenting genes, were upregulated, whereas the promoter demethylation was downregulated after decitabine exposure. Therefore, decitabine-based tumor microenvironment re-modulation could improve the effect of the PD-1 blockade. The application of decitabine in PD-1 blockade-based immunotherapy may elicit more potent immune responses, which can provide clinical benefits to the colorectal cancer patients with low microsatellite instability or stable microsatellites.
Project description:PD-1 blockade has demonstrated impressive clinical outcomes in colorectal cancers that have high microsatellite instability. However, the therapeutic efficacy for patients with tumors with low microsatellite instability or stable microsatellites needs further improvement. Here, we have demonstrated that low-dose decitabine could increase the expression of immune-related genes such as major histocompatibility complex genes and cytokine-related genes as well as the number of lymphocytes at the tumor site in CT26 colorectal cancer-bearing mice. A more significant inhibition of tumor growth and a prolongation of survival were observed in the CT26 mouse model after treatment with a combination of PD-1 blockade and decitabine than in mice treated with decitabine or PD-1 blockade alone. The anti-tumor effect of the PD-1 blockade was enhanced by low-dose decitabine. The results of RNA sequencing and whole-genome bisulfite sequencing of decitabine-treated CT26 cells and tumor samples with microsatellite stability from the patient tumor-derived xenograft model have shown that many immune-related genes, including antigen processing and antigen-presenting genes, were upregulated, whereas the promoter demethylation was downregulated after decitabine exposure. Therefore, decitabine-based tumor microenvironment re-modulation could improve the effect of the PD-1 blockade. The application of decitabine in PD-1 blockade-based immunotherapy may elicit more potent immune responses, which can provide clinical benefits to the colorectal cancer patients with low microsatellite instability or stable microsatellites.
Project description:PD-1 blockade has demonstrated impressive clinical outcomes in colorectal cancers that have high microsatellite instability. However, the therapeutic efficacy for patients with tumors with low microsatellite instability or stable microsatellites needs further improvement. Here, we have demonstrated that low-dose decitabine could increase the expression of immune-related genes such as major histocompatibility complex genes and cytokine-related genes as well as the number of lymphocytes at the tumor site in CT26 colorectal cancer-bearing mice. A more significant inhibition of tumor growth and a prolongation of survival were observed in the CT26 mouse model after treatment with a combination of PD-1 blockade and decitabine than in mice treated with decitabine or PD-1 blockade alone. The anti-tumor effect of the PD-1 blockade was enhanced by low-dose decitabine. The results of RNA sequencing and whole-genome bisulfite sequencing of decitabine-treated CT26 cells and tumor samples with microsatellite stability from the patient tumor-derived xenograft model have shown that many immune-related genes, including antigen processing and antigen-presenting genes, were upregulated, whereas the promoter demethylation was downregulated after decitabine exposure. Therefore, decitabine-based tumor microenvironment re-modulation could improve the effect of the PD-1 blockade. The application of decitabine in PD-1 blockade-based immunotherapy may elicit more potent immune responses, which can provide clinical benefits to the colorectal cancer patients with low microsatellite instability or stable microsatellites.
Project description:Inflammatory conditions caused by obstruction or perforation are common complications in colorectal cancer (CRC) and play important roles in tumor progression and immunosuppression. However, the significance of inflammatory conditions in the tumor response to immune checkpoint inhibitors (ICIs) remains unclear. We found a high microsatellite instability (MSI-H) CRC patient (Patient 1) whose primary tumor progressed and liver metastasis regressed during PD-1 blockade after having inflammatory conditions. Then, in 73 MSI-H CRCs, inflammatory conditions during ICI treatment were correlated with a poor tumor response, and an elevated NLR was associated with a poor immune status and resistance to ICIs. An organoid-T cell coculture model demonstrated an inhibited local immune response to treatment instead of systemic immunosuppression in Patient 1. Single-cell RNA sequencing suggested that neutrophils suppress the immune microenvironment mostly through CTLA-4-associated pathways. Therefore, inflammatory conditions in MSI-H CRCs correlate with resistance to ICIs through neutrophil-associated immunosuppression. Additional CTLA-4 blockade may improve the sensitivity to PD-1 blockade.
Project description:Dickkopf 1 (DKK1) could promote tumor progression by suppressing immunity. Therefore, we investigated whether DKK1 influence prognosis and sensitivity to PD-1 blockade in colorectal cancers (CRCs) with defective DNA mismatch repair genes (dMMR) or microsatellite instability (MSI). We found that elevated DKK1 expression was associated with recurrence and dismissed CD8+ T cell infiltrations, and patients with high serum DKK1 had poor anti-PD-1 response. RNA interference or neutralization of DKK1 in CRCs enhanced CD8+ T cell cytotoxicity, and down-regulation of T-bet and E2F1 following GSK3β activation was detected in DKK1-treated CD8+ T cells. In organoid-lymphocyte co-culture model, apoptosis proportions were elevated after individual neutralization of both PD-1 and DKK1, and the combined neutralization resulted in further increases. In conclusion, DKK1 suppresses tumor immunity in dMMR/MSI CRCs by inactivating CD8+ T cells through GSK3β/E2F1/T-bet axis. DKK1 neutralization may improve the sensitivity to PD-1 blockade in dMMR/MSI CRCs.
Project description:Goal: Microsatellite-instable (MSI) tumors are one of the few cancers that respond to immune checkpoint blockade (ICB); however, the mechanism of MSI status development is unclear. Here, we report that protein phosphatase 2A (PP2A) deletion or inactivation converted cold microsatellite-stable (MSS) into MSI tumors. Objectives: Using RNA sequencing data of three CT26-shppp2r1a data and a CT26-scr data, we demonstrate that these intestinal tumors display differential core driver pathways.
Project description:CD8+ exhausted T (Tex) cells are heterogeneous with distinct transcriptional and epigenetic landscapes. PD-1 inhibitors reinvigorate progenitor Tex cells, which subsequently differentiate into irresponsive terminal Tex cells and impair the longlasting antitumor response of PD-1 blockade therapy. How to maintain durable proliferative capacity of progenitor Tex cells is important but remains largely unknown. Here, we showed that low-dose DNA demethylating agent decitabine-pretreated CD8+ progenitor Tex cells had enhanced cytolytic activity against tumors after anti-PD-1 treatment in vitro and could not reactivate the terminal Tex cells. Decitabine-plus-anti-PD-1 treatment promoted the activation and expansion of endogenous tumor-infiltrated CD8+ progenitor Tex cells and efficiently suppressed tumor growth in multiple mice tumor models. The single-cell RNA-sequencing, TCR-sequencing and ATAC-sequencing demonstrated that decitabine-plus-anti-PD-1 combination altered the transcriptional and epigenetic status of CD8+ Tex cells and markedly elevated the clonally expansion and effector function of progenitor Tex cells as compared with anti-PD-1 monotherapy, presenting increased expression of genes associated with T cell activation, proliferation, cytolytic activity, memory and mitochondrial metabolism. Strikingly, decitabine-plus-anti-PD-1 combination sustained the expression and activity of AP-1 transcription factor JunD, which was reduced following PD-1 blockade therapy. Suppressing JNK/AP-1 signaling in CD8+ T cells blunted decitabine-plus-anti-PD-1-induced activation of CD8+ T cells. Together, our findings show that the epigenetic therapy remodels CD8+ progenitor Tex subset, improves responsiveness to anti-PD-1 therapy and suppresses CD8+ T cell terminal differentiation.
Project description:Immune checkpoint blockade (ICB) offers therapeutic options for patients with advanced colorectal cancer; however, only a subset of patients with microsatellite instability-high (MSI-H) tumors respond to treatment. Therefore, strategies to enhance immunotherapy sensitivity are urgently needed. In this study, we demonstrate that RBM15 is highly expressed in colorectal cancer and is associated with poor prognosis. Loss of RBM15 increases the expression of fumarate hydratase (FH), leading to a reduction in its substrate fumarate, which acts as a suppressor of anti-tumor immunity. Notably, RBM15 depletion delays tumor growth by promoting CD8+ T cell infiltration. Our findings identify RBM15 as a key suppressor of anti-tumor immunity, suggesting that targeting RBM15 could be a promising therapeutic strategy in colorectal cancer.
Project description:Colorectal cancer (CRC), a malignant tumor worldwide consists of microsatellite instability (MSI) and microsatellite stable (MSS) phenotypes. Although SHP2 is a potential target for cancer therapy, its relationship with innate immunosuppression remains elusive. To address that, single-cell RNA sequencing was performed to explore the role of SHP2 in all cell types of tumor microenvironment (TME) from murine MC38 xenografts.
Project description:Exercise training (ExT) has shown antitumor effects in many preclinical cancer models. In the present study, we utilize MC38 and CT26 cells, which represent MSI and MSS colorectal carcinomas respectively, to study the effects and mechanisms of ExT alone or in combination with PD-1 based immunotherapy. Using treadmill running and PD-1/PD-L1 blockade, we demonstrated that post-implant exercise training has broad anticancer activities in murine models of CRC. Specifically, in MSI CRC models, ExT induces beneficial metabolic and immunological adaptations, leading to a more significant inhibition in tumors treated with PD-1/PD-L1 blockade, suggesting a genotype-directed combinatory therapy for the subgroup of CRC patients. Moreover, ExT might be a safe and alternative anticancer strategy for cancers resistant to the PD-1 based immunotherapy, such as patients with MSS CRC tumors.