Abstract
Pancreatic ductal adenocarcinoma (PDA) shows a rich stroma where cancer-associated fibroblasts (CAFs) represent the major cell type. CAFs are master secretors of proteins with pro-tumor features.
CAF targeting remains a promising challenge for PDA, a devastating disease where treatments focusing on cancer cells have failed.
We previously introduced a novel pharmacological CAF-targeting approach using the somatostatin analog SOM230 (pasireotide) that inhibits protein synthesis in CAFs, and subsequent chemoprotective features of CAF secretome.
Using primary cultures of CAF isolated from human PDA resections, we here report that CAF secretome stimulates in vitro cancer cell survival, migration and invasive features, that are abolished when CAFs are treated with SOM230.
Mechanistically, SOM230 inhibitory effect on CAFs depends on the somatostatin receptor subtype sst1 expressed in CAFs but not in non-activated pancreatic fibroblasts, and on protein synthesis shutdown through eiF4E-Binding Protein-1 (4E-BP1) expression decrease.
We identify interleukin-6 as a SOM230-inhibited CAF-secreted effector, which stimulates cancer cell features through phosphoinositide 3-kinase activation.
In vivo, mice orthotopically co-xenografted with the human pancreatic cancer MiaPaCa-2 cells and CAFs develop pancreatic tumors, on which SOM230 treatment does not inhibit growth but abrogates metastasis.
Consistently, CAF secretome stimulates epithelial-to-mesenchymal transition in cancer cells, which is reversed upon CAF treatment with SOM230.
Our results highlight a novel promising anti-metastatic potential for SOM230 indirectly targeting pancreatic cancer cell invasion through pharmacological inhibition of stromal CAFs.
See also:
- Official Web Site: The Di Bella Method;
- Somatostatin in oncology, the overlooked evidences - In vitro, review and in vivo publications;
- Publication, 2018 Jul: Over-Expression of GH/GHR in Breast Cancer and Oncosuppressor Role of Somatostatin as a Physiological Inhibitor (from Di Bella's Foundation);
- Publication, 2019 Aug: The Entrapment of Somatostatin in a Lipid Formulation: Retarded Release and Free Radical Reactivity (from Di Bella's Foundation);
- Publication, 2019 Sep: Effects of Somatostatin and Vitamin C on the Fatty Acid Profile of Breast Cancer Cell Membranes (from Di Bella's Foundation);
- The Di Bella Method (A Fixed Part - Bromocriptine and/or Cabergoline);
- Pancreatic Adenocarcinoma: clinical records on 17 patients treated with Di Bella's Method;
- Complete objective response to biological therapy of plurifocal breast carcinoma;
- Neuroblastoma: Complete objective response to biological treatment;
- Oesophageal squamocellular carcinoma: a complete and objective response.
Supplementary Files