Genomic alterations drive metastases formation in pancreatic ductal adenocarcinoma cancer: deciphering the role of CDKN2A and CDKN2B in mediating liver tropism.

Metastases are often the direct cause of death from pancreatic ductal adenocarcinoma (PDAC). The role of genomic alterations (GA) in mediating tropism and metastasis formation by PDAC cells is currently unknown. We aimed to identify GAs predisposing colonization of PDAC cells to the liver and decipher mechanisms enabling this process. In order to reveal specific genes, we studied the frequency of GA in 8,880 local and 7,983 metastatic PDAC samples. We observed differential pattern of GA in the local tumor and specific metastatic sites, with liver metastases characterized by deletion of CDKN2A/B (encoding p16/p15, respectively). The role of CDKN2A/B in promoting liver metastasis was evidenced by enhanced tumorigenic phenotype of p15/p16-deleted PDAC cells when exposed to hepatocytes conditioned media. The liver is characterized by high-ammonia low-glutamine environment and transcriptomic assays indicated unique adaptation of PDAC cells to these conditions, including regulation of genes leading to reduced glutaminolysis, like overexpression of GLUL and reduction in GLS2. Furthermore, metabolic assays indicated an increase in glutamate derived from [U-13C]-glucose in p15/p16-deleted cells. Importantly, these cells thrived under high ammonia condition. These data suggest a unique role for genomic alterations in mediating tropism of PDAC. Among these alterations, p15/16 deletion was identified as a promoter of liver metastases. Further studies indicated a unique role for p15/16 in regulating glutaminolysis. These findings reveal vulnerabilities in PDAC cells, which may pave the way for the development of novel therapeutic strategies aiming at the prevention of liver metastases formation.

Ligand-binding Domain-activating Mutations of ESR1 Rewire Cellular Metabolism of Breast Cancer Cells.

PURPOSE: Mutations in the ligand-binding domain (LBD) of estrogen receptor α (ER) confer constitutive transcriptional activity and resistance to endocrine therapies in patients with breast cancer. Accumulating clinical data suggest adverse outcome for patients harboring tumors expressing these mutations. We aimed to elucidate mechanisms conferring this aggressive phenotype. EXPERIMENTAL DESIGN: Cells constitutively expressing physiologic levels of ER-harboring activating LBD mutations were generated and characterized for viability, invasiveness, and tumor formation in vivo. Gene expression profile was studied using microarray and RNAseq technologies. Metabolic properties of the cells were assessed using global metabolite screen and direct measurement of metabolic activity. RESULTS: Cells expressing mutated ER showed increased proliferation, migration, and in vivo tumorigenicity compared with cells expressing the wild-type ER (WT-ER), even in the presence of estrogen. Expression of the mutated ER was associated with upregulation of genes involved in invasion and metastases, as well as elevation of genes associated with tumor cell metabolism. Indeed, a metabolic examination revealed four distinct metabolic profiles: WT-ER-expressing cells either untreated or estrogen treated and mutated ER-expressing cells either untreated or estrogen treated. Pathway analyses indicated elevated tricarboxylic acid cycle activity of 537S-ER-expressing cells. Thus, while WT-ER cells were mostly glucose-dependent, 537S-ER were not addicted to glucose and were able to utilize glutamine as an alternative carbon source. CONCLUSIONS: Taken together, these data indicate estrogen-independent rewiring of breast cancer cell metabolism by LBD-activating mutations. These unique metabolic activities may serve as a potential vulnerability and aid in the development of novel treatment strategies to overcome endocrine resistance.