"Every Cloud Has a Silver Lining": How Three Rare Diseases Defend Themselves from COVID-19 and What We Have Learnt from It

The process of SARS-CoV-2 infection, responsible for the COVID-19 pandemic, is carried out through different steps, with the interaction between ACE2 and Spike protein (S) being crucial. Besides of that, the acidic environment of endosomes seems to play a relevant role in the virus uptake into cells and its intracellular replication. Patients affected by two rare genetic tubulopathies, Gitelman's and Bartter's Syndromes, and a rare genetic metabolic disease, Fabry Disease, have shown intrinsic protection from SARS-CoV-2 infection and COVID-19 on account of specific intrinsic features that interfere with the virus uptake into cells and its intracellular replication, which will be reported and discussed in this paper, providing interesting insights for present and future research.

Molecular docking and dynamic simulations of quinoxaline 1,4-di-N-oxide as inhibitors for targets from Trypanosoma cruzi, Trichomonas vaginalis, and Fasciola hepatica

CONTEXT

Quinoxaline 1,4-di-N-oxide is a scaffold with a wide array of biological activities, particularly its use to develop new antiparasitic agents. Recently, these compounds have been described as trypanothione reductase (TR), triosephosphate isomerase (TIM), and cathepsin-L (CatL) inhibitors from Trypanosoma cruzi, Trichomonas vaginalis, and Fasciola hepatica, respectively.

METHODS

Therefore, the main objective of this work was to analyze quinoxaline 1,4-di-N-oxide derivatives of two databases (ZINC15 and PubChem) and literature by molecular docking, dynamic simulation and complemented by MMPBSA, and contact analysis of molecular dynamics' trajectory on the active site of the enzymes to know their potential effect inhibitory. Interestingly, compounds Lit_C777 and Zn_C38 show preference as potential TcTR inhibitors over HsGR, with favorable energy contributions from residues including Pro398 and Leu399 from Z-site, Glu467 from γ-Glu site, and His461, part of the catalytic triad. Compound Lit_C208 shows potential selective inhibition against TvTIM over HsTIM, with favorable energy contributions toward TvTIM catalytic dyad, but away from HsTIM catalytic dyad. Compound Lit_C388 was most stable in FhCatL with a higher calculated binding energy by MMPBSA analysis than HsCatL, though not interacting with catalytic dyad, holding favorable energy contribution from residues oriented at FhCatL catalytic dyad. Therefore, these kinds of compounds are good candidates to continue researching and confirming their activity through in vitro studies as new selective antiparasitic agents.

Structural and Biochemical Analysis of the Dual Inhibition of MG-132 against SARS-CoV-2 Main Protease (Mpro/3CLpro) and Human Cathepsin-L

After almost two years from its first evidence, the COVID-19 pandemic continues to afflict people worldwide, highlighting the need for multiple antiviral strategies. SARS-CoV-2 main protease (Mpro/3CLpro) is a recognized promising target for the development of effective drugs. Because single target inhibition might not be sufficient to block SARS-CoV-2 infection and replication, multi enzymatic-based therapies may provide a better strategy. Here we present a structural and biochemical characterization of the binding mode of MG-132 to both the main protease of SARS-CoV-2, and to the human Cathepsin-L, suggesting thus an interesting scaffold for the development of double-inhibitors. X-ray diffraction data show that MG-132 well fits into the Mpro active site, forming a covalent bond with Cys145 independently from reducing agents and crystallization conditions. Docking of MG-132 into Cathepsin-L well-matches with a covalent binding to the catalytic cysteine. Accordingly, MG-132 inhibits Cathepsin-L with nanomolar potency and reversibly inhibits Mpro with micromolar potency, but with a prolonged residency time. We compared the apo and MG-132-inhibited structures of Mpro solved in different space groups and we identified a new apo structure that features several similarities with the inhibited ones, offering interesting perspectives for future drug design and in silico efforts.

Cancer-associated mutations reveal a novel role for EpCAM as an inhibitor of cathepsin-L and tumor cell invasion

Background

EpCAM (Epithelial cell adhesion molecule) is often dysregulated in epithelial cancers. Prior studies implicate EpCAM in the regulation of oncogenic signaling pathways and epithelial-to-mesenchymal transition. It was recently demonstrated that EpCAM contains a thyroglobulin type-1 (TY-1) domain. Multiple proteins with TY-1 domains are known to inhibit cathepsin-L (CTSL), a cysteine protease that promotes tumor cell invasion and metastasis. Analysis of human cancer sequencing studies reveals that somatic EpCAM mutations are present in up to 5.1% of tested tumors.

Methods

The Catalogue of Somatic Mutations in Cancer (COSMIC) database was queried to tabulate the position and amino acid changes of cancer associated EpCAM mutations. To determine how EpCAM mutations affect cancer biology we studied C66Y, a damaging TY-1 domain mutation identified in liver cancer, as well as 13 other cancer-associated EpCAM mutations. In vitro and in vivo models were used to determine the effect of wild type (WT) and mutant EpCAM on CTSL activity and invasion. Immunoprecipitation and localization studies tested EpCAM and CTSL protein binding and determined compartmental expression patterns of EpCAM mutants.

Results

We demonstrate that WT EpCAM, but not C66Y EpCAM, inhibits CTSL activity in vitro, and the TY-1 domain of EpCAM is responsible for this inhibition. WT EpCAM, but not C66Y EpCAM, inhibits tumor cell invasion in vitro and lung metastases in vivo. In an extended panel of human cancer cell lines, EpCAM expression is inversely correlated with CTSL activity. Previous studies have demonstrated that EpCAM germline mutations can prevent EpCAM from being expressed at the cell surface. We demonstrate that C66Y and multiple other EpCAM cancer-associated mutations prevent surface expression of EpCAM. Cancer-associated mutations that prevent EpCAM cell surface expression abrogate the ability of EpCAM to inhibit CTSL activity and tumor cell invasion.

Conclusions

These studies reveal a novel role for EpCAM as a CTSL inhibitor, confirm the functional relevance of multiple cancer-associated EpCAM mutations, and suggest a therapeutic vulnerability in cancers harboring EpCAM mutations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08239-z.

A Cathepsin-L is required for invasive behavior during Air Sac Primordium development in Drosophila melanogaster

The Drosophila Air Sac Primordium (ASP) has emerged as an important structure where cellular, genetic and molecular events responsible for invasive behavior and branching morphogenesis can be studied. In this report we present data which demonstrate that a Cathepsin-L encoded by the gene CP1 in Drosophila is necessary for invasive behavior during ASP development. We find that CP1 is expressed in ASP and knockdown of CP1 results in suppression of migratory and invasive behavior observed during ASP development. We further show that CP1 possibly regulates invasive behavior by promoting degradation of Basement Membrane. Our data provide clues to the possible role of Cathepsin L in human lung development and tumor invasion, especially, given the similarities between human lung and Drosophila ASP development.

Serum HE4, CA125, YKL-40, bcl-2, cathepsin-L and prediction optimal debulking surgery, response to chemotherapy in ovarian cancer

Background

The most important prognostic factor in the ovarian cancer is optimal cytoreduction. The neoadjuvant chemotherapy, an only optional method of treatment in this case and is still the subject of debate. The object of this study was to evaluate the usefulness of markers: CA 125, HE4, YKL-40 and bcl-2 as well as cathepsin L in predicting optimal cytoreduction and response to chemotherapy.

Methods

Sera were secured preoperatively. The division into groups was performed retrospectively depending on the method of treatment (surgery vs neoadjuvant chemotherapy) as well as on response to chemotherapy (sensitive vs resistant vs refractory). Comparisons were made between groups, and the diagnostic usefulness of tested proteins was examined.

Results

We found that statistically significant differences between primary operated patients and patients undergoing neoadjuvant chemotherapy were applicable only to the tumour markers (CA125 1206.79 vs 2432.38, p = 0.000191; HE4 78.87 vs 602.45, p = 0.000004; YKL-40 108.13 vs 203.96, p = 0.003991). Cathepsin-L and Bcl-2 were statistically insignificant. The cut-off point values were determined for the CA 125 (345 mIU/ml), HE4 (218.43 pmol/L) and YKL-40 (140.9 ng/ml). The sensitivity, specificity, PPV and NPV were as follows: CA125 (83.3%; 75%; 80.6%; 78.3%), HE4 (86.6%; 91.3%; 92.9%; 84%) and YKL-40 (75%; 83.3%; 84%; 74.1%).

Conclusion

Among the tested proteins the HE4 marker appears to be helpful in forecasting of optimal cytoreduction and possibly also of the prediction of response to platinum analogues used in first-line treatment of ovarian cancer.