Novel Approaches and Challenges of Discovery of Exosite Modulators of a Disintegrin and Metalloprotease 10

Combined proteomics and CRISPR‒Cas9 screens in PDX identify ADAM10 as essential for leukemia in vivo

BACKGROUND

Acute leukemias represent deadly malignancies that require better treatment. As a challenge, treatment is counteracted by a microenvironment protecting dormant leukemia stem cells.

METHODS

To identify responsible surface proteins, we performed deep proteome profiling on minute numbers of dormant patient-derived xenograft (PDX) leukemia stem cells isolated from mice. Candidates were functionally screened by establishing a comprehensive CRISPR‒Cas9 pipeline in PDX models in vivo.

RESULTS

A disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) was identified as an essential vulnerability required for the survival and growth of different types of acute leukemias in vivo, and reconstitution assays in PDX models confirmed the relevance of its sheddase activity. Of translational importance, molecular or pharmacological targeting of ADAM10 reduced PDX leukemia burden, cell homing to the murine bone marrow and stem cell frequency, and increased leukemia response to conventional chemotherapy in vivo.

CONCLUSIONS

These findings identify ADAM10 as an attractive therapeutic target for the future treatment of acute leukemias.

Differential expression of "A Disintegrin and Metalloproteinase 10" in hepatocellular carcinoma and the noncancerous hepatic tissues: Contribution to HCV-promoted hepatocarcinogenesis

Background

A disintegrin and metalloproteinases (ADAMs) have emerged as therapeutic targets in many cancers. ADAM10 was particularly studied in hepatocellular carcinoma (HCC) for its potential role in hepatocarcinogenesis and HCC progression.

Objective

To investigate the immunohistochemical (IHC) expression of ADAM10 in HCCs and the adjacent noncancerous tissues from 70 HCC patients, attempting to elucidate any association between ADAM10 and HCC development and/or progression.

Materials and Methods

IHC staining for anti-ADAM10 was performed using horseradish peroxidase technique. An extent and intensity-dependent scoring was applied dividing samples into high- and low-expression groups. HCCs were statistically compared in relation with gender, age, cirrhosis, hepatitis C virus (HCV) status, alpha-fetoprotein (AFP) serum level, tumor size, multiplicity, encapsulation/invasion, grade, histological pattern and variant, mitosis, necrosis, vascular emboli, portal thrombosis, stage, recurrence, and mortality. Kaplan-Meier's method was used to analyze disease-free and overall survival (DFS and OS).

Results

ADAM10 was expressed in 77.1% of HCCs compared with 42.9% of noncancerous tissues. Differential expression showed significant statistical difference (P = 0.02), as 38.6% of HCCs showed high expression, whereas 92.8% of noncancerous samples showed low expression. No significant differences were observed when high- and low-ADAM10 expression HCCs were compared with respect to all tested prognostic parameters except the HCV status. Patients whose tumors showed high-ADAM10 expression had relatively longer DFS and OS times, but with insignificant log-rank differences.

Conclusions

ADAM10 is frequently expressed in HCCs compared with noncancerous hepatic tissues suggesting its role in hepatocarcinogenesis, especially in association with HCV. It has no association with HCC progression or survival. Further studies should be sought to investigate its validity as a therapeutic target.

ADAM10-a "multitasker" in sepsis: focus on its posttranslational target

BACKGROUND

Sepsis has a complex pathogenesis in which the uncontrolled systemic inflammatory response triggered by infection leads to vascular barrier disruption, microcirculation dysfunction and multiple organ dysfunction syndrome. Numerous recent studies reveal that a disintegrin and metalloproteinase 10 (ADAM10) acts as a "molecular scissor" playing a pivotal role in the inflammatory response during sepsis by regulating proteolysis by cleaving various membrane protein substrates, including proinflammatory cytokines, cadherins and Notch, which are involved in intercellular communication. ADAM10 can also act as the cellular receptor for Staphylococcus aureus α-toxin, leading to lethal sepsis. However, its substrate-specific modulation and precise targets in sepsis have not yet to be elucidated.

METHODS

We performed a computer-based online search using PubMed and Google Scholar for published articles concerning ADAM10 and sepsis.

CONCLUSIONS

In this review, we focus on the functions of ADAM10 in sepsis-related complex endothelium-immune cell interactions and microcirculation dysfunction through the diversity of its substrates and its enzymatic activity. In addition, we highlight the posttranslational mechanisms of ADAM10 at specific subcellular sites, or in multimolecular complexes, which will provide the insight to intervene in the pathophysiological process of sepsis caused by ADAM10 dysregulation.

MT1-MMP and ADAM10/17 exhibit a remarkable overlap of shedding properties

Membrane-type-I matrix metalloproteinase (MT1-MMP) is one of six human membrane-bound MMPs and is responsible for extracellular matrix remodelling by degrading several substrates like fibrillar collagens, including types I-III, or fibronectin. Moreover, MT1-MMP was described as a key player in cancer progression and it is involved in various inflammatory processes, as well as in the pathogenesis of Alzheimer's disease (AD). The membrane-tethered metalloprotease meprin β as well as a disintegrin and metalloproteinase 10 (ADAM10) and ADAM17 are also associated with these diseases. Interestingly, meprin β, ADAM10/17 and MT1-MMP also have a shared substrate pool including the interleukin-6 receptor and the amyloid precursor protein. We investigated the interaction of these proteases, focusing on a possible connection between MT1-MMP and meprin β, to elucidate the potential mutual regulations of both enzymes. Herein, we show that besides ADAM10/17, MT1-MMP is also able to shed meprin β from the plasma membrane, leading to the release of soluble meprin β. Mass spectrometry-based cleavage site analysis revealed that the cleavage of meprin β by all three proteases occurs between Pro₆₀₂ and Ser₆₀₃ , N-terminal of the EGF-like domain. Furthermore, only inactive human pro-meprin β is shed by MT1-MMP, which is again in accordance with the shedding capability observed for ADAM10/17. Vice versa, meprin β also appears to shed MT1-MMP, indicating a complex regulatory network. Further studies will elucidate this well-orchestrated proteolytic web under distinct conditions in health and disease and will possibly show whether the loss of one of the above-mentioned sheddases can be compensated by the other enzymes.