Project description:We used CRISPR/Cas9 genome editing to inactivate KRAS in pancreatic cancer cells and isolated cell populations that still produce tumors in mice. We show that the malignant phenotype of KRAS knockout cells is stable. However, KRAS deficient cancer cells fail to avoid detection and elimination by the host immune system, indicating that a key aspect of tumor maintenance by oncogenic KRAS is to promote immune evasion. Our study uncovers changes both in cancer cells and stromal immunoreactive cells attributable to KRAS expression. Complementation studies indicate that BRAF, AKT and MYC are causative drivers of KRAS-mediated immune suppression. These results show that combination treatments that both target KRAS signaling and boost antitumor immunity will be an effective strategy to treat PDAC.
Project description:Pancreatic cancer is characterised by the prevalence of oncogenic mutations in KRAS. Previous studies have reported that altered Kras gene dosage drives progression and metastatic incidence in pancreatic cancer. While the role of oncogenic KRAS mutation is well characterised, the relevance of the partnering wild-type KRAS allele in pancreatic cancer is less well understood and controversial. Using in vivo mouse modelling of pancreatic cancer, we demonstrate that wild-type Kras restrains the oncogenic impact of mutant Kras, and drastically impacts both Kras-mediated tumourigenesis and therapeutic response. Mechanistically, deletion of wild-type Kras increases oncogenic Kras signalling through the downstream MAPK effector pathway, driving pancreatic intraepithelial neoplasia (PanIN) initiation. In addition, in the KPC mouse model, a more aggressive model of pancreatic cancer, loss of wild-type KRAS leads to accelerated initiation but delayed tumour progression. These tumours had altered stroma, downregulated Myc levels and an enrichment for immunogenic gene signatures. Importantly, loss of wild-type Kras sensitises Kras mutant tumours to MEK1/2 inhibition though tumours eventually become resistant and then rapidly progress. This study demonstrates the repressive role of wild-type Kras during pancreatic tumourigenesis and highlights the critical impact of the presence of wild-type KRAS on tumourigenesis and therapeutic response in pancreatic cancer.
Project description:Kirsten rat sarcoma virus (KRAS) signaling drives pancreatic ductal adenocarcinoma (PDAC) malignancy, which is an unmet clinical need. Here we identify a disintegrin and metalloproteinase domain 9 (ADAM9) as a modulator of PDAC progression via stabilization of wild-type and mutant KRAS proteins. Mechanistically, ADAM9 loss increases the interaction of KRAS with plasminogen activator inhibitor-1 (PAI-1), which functions as a selective autophagy receptor in conjunction with LC3, triggering the lysosomal degradation of KRAS. Suppression of ADAM9 by a small molecule inhibitor restricts disease progression in spontaneous models, and the combination with gemcitabine elicits dramatic regression of patient-derived tumors. Our findings provide a promising strategy to target the KRAS signaling cascade and demonstrate a potential modality to enhance sensitivity to chemotherapy in PDAC.
Project description:We discovered that KRAS-mutant lung adenocarcinomas (LADC) co-opt CREB in order to evade the innate immune system: KRAS-driven CREB activation in LADC suppresses the expression of CXCR1 ligands that would otherwise recruit neutrophils to the tumor site. CREB was overexpressed in murine KRAS-mutant LADC, pulmonary Creb1-deletion inhibited disease development, and Creb1-overexpression boosted the tumorigenicity of KRAS-mutant cells. Conditional Creb1 deletion in Kras-mutant LADC cells caused overexpression of CXCR1/2 ligands, and lung tumor-bearing Creb1-deleted mice displayed increased pulmonary neutrophils. Cxcr1-deficient mice were selectively permissive to KRAS-mutant tumor growth and showed defective neutrophil recruitment. The pro-tumor effects of CREB required intact host-Cxcr1 and those of host-Cxcr1 necessitated mutant KRAS in cancer cells. Pharmacologic CREB blockade prevented tumor growth and restored neutrophil recruitment only when initiated before immune evasion of KRAS-mutant LADC cells. CREB and CXCR1 expression were respectively restricted to tumor and stromal cells of human LADC, while CREB-controlled genes profoundly impacted survival. In summary, CREB-mediated immune evasion of KRAS-mutant LADC rests on signaling to myeloid CXCR1 and is actionable.
Project description:We utilized non-transformed, human pancreatic ductal epithelial (HPDE) cells, previously engineered with the E6 and E7 proteins of the HPV16 virus to emulate loss of p53 and inactivation of the Rb pathway, respectively. Given the frequent activation of KRAS (>90% PDAC tumors) and its early role in pancreatic neoplasia, we sought to engineer HPDE cells containing KRASG12D to provide the appropriate context in which to screen for novel drivers that might represent KRAS effectors. The KRAS-induced transcription analysis was conducted using RNAs extracted from HPDE cells transduced with either control, wild-type KRAS or KRASG12D(pInducer) with or without DOX (100ng/ml) for 72 h, followed by hybridization of labeled cDNA onto Agilent arrays (Agilent G3 Human GE 8x60K) by the Baylor College of Medicine Genome Profiling Core Facility. multi-group comparison
Project description:Kirsten rat sarcoma virus (KRAS) signaling drives pancreatic ductal adenocarcinoma (PDAC) malignancy, which is an unmet clinical need. Here we identify a disintegrin and metalloproteinase domain 9 (ADAM9) as a modulator of PDAC progression via stabilization of wild-type and mutant KRAS proteins. Mechanistically, ADAM9 loss increases the interaction of KRAS with plasminogen activator inhibitor-1 (PAI-1), which functions as a selective autophagy receptor in conjunction with LC3, triggering the lysosomal degradation of KRAS. Suppression of ADAM9 by a small molecule inhibitor restricts disease progression in spontaneous models, and the combination with gemcitabine elicits dramatic regression of patient-derived tumors. Our findings provide a promising strategy to target the KRAS signaling cascade and demonstrate a potential modality to enhance sensitivity to chemotherapy in PDAC.