Integrated proteomic profiling identifies amino acids selectively cytotoxic to pancreatic cancer cells.

Pancreatic adenocarcinoma (PDAC) is one of the most deadly cancers, characterized by extremely limited therapeutic options and a poor prognosis, as it is often diagnosed during late disease stages. Innovative and selective treatments are urgently needed, since current therapies have limited efficacy and significant side effects. Through proteomics analysis of extracellular vesicles, we discovered an imbalanced distribution of amino acids secreted by PDAC tumor cells. Our findings revealed that PDAC cells preferentially excrete proteins with certain preferential amino acids, including isoleucine and histidine, via extracellular vesicles. These amino acids are associated with disease progression and can be targeted to elicit selective toxicity to PDAC tumor cells. Both in vitro and in vivo experiments demonstrated that supplementation with these specific amino acids effectively eradicated PDAC cells. Mechanistically, we also identified XRN1 as a potential target for these amino acids. The high selectivity of this treatment method allows for specific targeting of tumor metabolism with very low toxicity to normal tissues. Furthermore, we found this treatment approach is easy-to-administer and with sustained tumor-killing effects. Together, our findings reveal that exocytosed amino acids may serve as therapeutic targets for designing treatments of intractable PDAC and potentially offer alternative treatments for other types of cancers.

Integrin ß1 is a key determinant of the expression of angiotensin-converting enzyme 2 (ACE2) in the kidney epithelial cells.

The expression of the angiotensin-converting enzyme 2 (ACE2) is altered in multiple chronic kidney diseases like hypertension and renal fibrosis, where the signaling from the basal membrane proteins is critical for the development and progression of the various pathologies. Integrins are heterodimeric cell surface receptors that have important roles in the progression of these chronic kidney diseases by altering various cell signaling pathways in response to changes in the basement membrane proteins. It is unclear whether integrin or integrin-mediated signaling affects the ACE2 expression in the kidney. The current study tests the hypothesis that integrin ß1 regulates the expression of ACE2 in kidney epithelial cells. The role of integrin ß1 in ACE2 expression in renal epithelial cells was investigated by shRNA-mediated knockdown and pharmacological inhibition. In vivo studies were carried out using epithelial cell-specific deletion of integrin ß1 in the kidneys. Deletion of integrin ß1 from the mouse renal epithelial cells reduced the expression of ACE2 in the kidney. Furthermore, the downregulation of integrin ß1 using shRNA decreased ACE2 expression in human renal epithelial cells. ACE2 expression levels were also decreased in renal epithelial cells and cancer cells when treated with an integrin α2ß1 antagonist, BTT 3033. SARS-CoV-2 viral entry to human renal epithelial cells and cancer cells was also inhibited by BTT 3033. This study demonstrates that integrin ß1 positively regulates the expression of ACE2, which is required for the entry of SARS-CoV-2 into kidney cells.

Integrin ß1 Promotes Pancreatic Tumor Growth by Upregulating Kindlin-2 and TGF-ß Receptor-2.

The tumor microenvironment plays a critical role in defining the growth and malignancy of solid tumors. Extracellular matrix (ECM) proteins such as collagen, vitronectin, and fibronectin are major components of the tumor microenvironment. Tumor growth-promoting reciprocal interaction between ECM and cytoplasmic proteins is regulated by the cell surface receptors called integrins. This study investigated the mechanism by which integrin ß1 promotes pancreatic tumor growth. In MIA PaCa-2 pancreatic cancer cell line, the loss of integrin ß1 protein reduced the ability of cells to proliferate in a 3D matrix and compromised the ability to form a focal adhesion complex. Decreased expression of integrin α5 was observed in KO cells, which resulted in impaired cell spreading and adhesion on vitronectin and fibronectin. Reduced expression of the integrin-associated protein, kindlin-2 was also recorded. The downregulation of kindlin-2 decreased the phosphorylation of Smad2/3 by reducing the expression of TGF-ß receptor 2. These results unravel a new mechanism of integrin ß1 in tumor growth by modifying the expression of kindlin-2 and TGF-ß receptor 2 signaling.