(Arg)9-SH2 superbinder: a novel promising anticancer therapy to melanoma by blocking phosphotyrosine signaling

CoDIAC: A comprehensive approach for interaction analysis reveals novel insights into SH2 domain function and regulation

Protein domains are conserved structural and functional units and are the functional building blocks of proteins. Evolutionary expansion means that domain families are often represented by many members in a species, which are found in various configurations with other domains, which have evolved new specificity for interacting partners. Here, we develop a structure-based interface analysis to comprehensively map domain interfaces from available experimental and predicted structures, including interfaces with other macromolecules and intraprotein interfaces (such as might exist between domains in a protein). We hypothesized that a comprehensive approach to contact mapping of domains could yield new insights. Specifically, we use it to gain information about how domains selectivity interact with ligands, whether domain-domain interfaces of repeated domain partnerships are conserved across diverse proteins, and identify regions of conserved post-translational modifications, using relationship to interaction interfaces as a method to hypothesize the effect of post-translational modifications (and mutations). We applied this approach to the human SH2 domain family, an extensive modular unit that is the foundation of phosphotyrosine-mediated signaling, where we identified a novel approach to understanding the binding selectivity of SH2 domains and evidence that there is coordinated and conserved regulation of multiple SH2 domain binding interfaces by tyrosine and serine/threonine phosphorylation and acetylation, suggesting that multiple signaling systems can regulate protein activity and SH2 domain interactions in a regulated manner. We provide the extensive features of the human SH2 domain family and this modular approach, as an open source Python package for COmprehensive Domain Interface Analysis of Contacts (CoDIAC).

Blockade of DDR1/PYK2/ERK signaling suggesting SH2 superbinder as a novel autophagy inhibitor for pancreatic cancer

Pancreatic cancer is highly lethal, of which 90% is pancreatic ductal adenocarcinoma (PDAC), with a 5-year survival rate of less than 12%, lacking effective treatment options and late diagnosis. Furthermore, the tumors show an intense resistance to cytotoxic chemotherapies. As autophagy is elevated in PDAC, targeting the autophagic pathway is regarded as a promising strategy for cancer treatment. Immunofluorescence and transmission electron microscopy were utilized to assess the autophagic flux. Label-free quantitative phosphoproteomics was used to figure out critically altered tyrosine phosphorylation of the proteins. Tumor-bearing mice were used to validate that SH2 TrM-(Arg)9 restrained the growth of tumor cells. SH2 TrM-(Arg)9 inhibited collagen-induced autophagy via blocking the DDR1/PYK2/ERK signaling cascades. SH2 TrM-(Arg)9 improved the sensitivity of PANC-1/GEM cells to gemcitabine (GEM). Inhibition of autophagy by SH2 TrM-(Arg)9 may synergized with chemotherapy and robusted tumor suppression in pancreatic cancer xenografts. SH2 TrM-(Arg)9 could enter into PDAC cells and blockade autophagy through inhibiting DDR1/PYK2/ERK signaling and may be a new treatment strategy for targeted therapy of PDAC.

Au-24 as a Potential Thioredoxin Reductase Inhibitor in Hepatocellular Carcinoma Cells

A novel TrxR inhibitor Au-24 and its inhibitory ability to hepatocellular carcinoma in vitro and in vivo is reported herein. Au-24 can suppress HepG2 cells from proliferating by lowering mitochondrial membrane potential (MMP) and increasing reactive oxygen species (ROS) levels, resulting in oxidative stress, which causes DNA damage, autophagy, cell cycle arrest, and apoptosis. This compound can also affect the normal function of apoptosis, MAPK, PI3K/AKT/mTOR, NF-κB, STAT3 signaling pathways. In vivo experiments revealed that Au-24 inhibited HepG2 tumor growth more effectively than AA1 (chloro(triethylphosphine)gold(I)) by decreasing Ki67 and CD31 protein expression and promoting tumor cell apoptosis and necrosis lesions. As a result, Au-24 was found to be a promising candidate as a TrxR inhibitor for the treatment of hepatocellular carcinoma (HCC) in both in vivo and in vitro experiments.

Rosmarinic Acid Decreases the Malignancy of Pancreatic Cancer Through Inhibiting Gli1 Signaling

BACKGROUND

Rosmarinic acid (RA) has been shown to exert anti-tumor effects on various types of cancer. However, its roles in the treatment of pancreatic ductal adenocarcinoma (PDAC) and the underlying mechanisms remain elusive.

PURPOSE

The present study aimed to investigate the therapeutic effects of RA on PDAC as well as the underlying mechanisms.

STUDY DESIGN

Evaluation of the effects of RA on PDAC malignancy both in vitro and in vivo.

METHODS

Cell counting kit 8 (CCK8) assay, colony formation assay, 5-Ethynyl-2'-deoxyuridine (EDU) incorporation assay, cell cycle analysis, and apoptosis assay were conducted to assess the inhibitory effect of RA on PDAC cell proliferation. Meanwhile, western blotting and RT-qPCR assay were performed to detect the target gene expression at protein and mRNA levels, respectively. Moreover, the in vivo anti-tumor activities of RA were assayed in an xenograft mouse model of PDAC.

RESULTS

RA dramatically down-regulated Gli1 and its downstream targets. Further studies showed that RA prevents the nuclear translocation of Gli1, while promoting the degradation of cytosolic Gli1 via the proteasome pathway. Moreover, we observed that RA induced G1/S cell cycle arrest and apoptosis in the PDAC cells through regulating the expression of P21, P27, CDK2, Cyclin E, Bax, and Bcl-2, it inhibited the PDAC cell migration and invasion via E-cadherin and MMP-9. Notably, Gli1 overexpression markedly reversed the above RA-induced effects on PDAC cells, whereas Gli1 knockdown enhanced the effects. Additionally, the in vivo assays demonstrated that RA suppresses the tumor growth of PDAC presumably by inhibiting Gli1.

CONCLUSION

We provided evidence that RA restrained the nuclear translocation of Gli1 and facilitates Gli1 degradation via proteasome pathway, reducing the malignancy of PDAC cells. These findings implicated RA as a therapeutic agent for PDAC.

Aptamer-SH2 superbinder-based targeted therapy for pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) exhibits the poorest prognosis of all solid tumors with a 5-year survival rate of less than 10% and a median survival of 6 months after diagnosis. Numerous targeted agents have been developed and evaluated to improve the survival benefit in patients with PDAC. Unfortunately, most agents have been proven futile mainly owing to the dense stroma and the sophisticated signaling pathways of PDAC. Here, we show the potent effectiveness of Aptamer-SH2 superbinder-(Arg)9 conjugate on the treatment of PDAC. In this conjugate, DNA aptamer selected against PDAC cell line confers the function of specifically recognizing and binding to the PDAC cells and activated pancreatic stellate cells (PSCs) in stroma; cell penetrating peptide (Arg)9 facilitates the intracellular delivery of fused proteins; SH2 superbinder conducts the drastic blockade of multiple phosphotyrosines (pY)-based signaling pathways in tumor cells.

METHODS

PDAC-associated pY were reanalyzed by bioinformatics screen. XQ-2d and SH2 superbinder-(Arg)9 were crosslinked with BMH to form XQ-2d-SH2 CM-(Arg)9 conjugate. Immunofluorescence was utilized to assess the potency of the conjugate entering cells. MTT and wound healing assays were performed to evaluate the proliferation or migration of PANC-1 and BxPC-3 cells, respectively. Western blot and Pulldown assays revealed that conjugate influenced several pY-based signaling pathways. Tumor-bearing mice were used to validate XQ-2d-SH2 CM-(Arg)9, which restrained the growth and metastasis of cancer cells.

RESULTS

XQ-2d-His-SH2 CM-(Arg)9 conjugate restrained proliferation, invasion, and metastasis of PDAC cells with potent efficacy via blocking the activity of several pY-related signaling cascades. XQ-2d-His-SH2 CM-(Arg)9 could eliminate the dense stroma of PDAC and then arrive at tumor tissues.

CONCLUSIONS

XQ-2d-SH2 CM-(Arg)9 conjugate may efficiently destroy the pancreatic stroma and show potent antitumor efficacy with minimal toxic effect by regulating tumor cell proliferation and metastasis in vitro and in vivo, which makes it to be a promising targeted therapy of PDAC.

miR-362-3p acts as a tumor suppressor by targeting SERBP1 in ovarian cancer

BACKGROUND

Ovarian cancer is the leading lethal gynecological cancer and is generally diagnosed during late-stage presentation. In addition, patients with ovarian cancer still face a low 5-year survival rate. Thus, innovative molecular targeting agents are required to overcome this disease. The present study aimed to explore the function of miR-362-3p and the underlying molecular mechanisms influencing ovarian cancer progression.

METHODS

The expression levels of miR-362-3p were determined using qRT-PCR. Gain-of-function and loss-of-function methods were used to detect the effects of miR-362-3p on cell proliferation, cell migration, and tumor metastasis in ovarian cancer. A luciferase reporter assay was performed to confirm the potential target of miR-362-3p, and a rescue experiment was employed to verify the effect of miR-362-3p on ovarian cancer by regulating its target gene.

RESULTS

miR-362-3p was significantly downregulated in ovarian cancer tissues and cell lines. In vitro, our data showed that miR-362-3p suppressed cell proliferation and migration. In vivo, miR-362-3p inhibited ovarian cancer growth and metastasis. Mechanistically, SERBP1 was identified as a direct target and functional effector of miR-362-3p in ovarian cancer. Moreover, SERBP1 overexpression rescued the biological function of miR-362-3p.

CONCLUSIONS

Our data reveal that miR-362-3p has an inhibitory effect on ovarian cancer. miR-362-3p inhibits the development and progression of ovarian cancer by directly binding its target gene SERBP1.

Revisiting the phosphotyrosine binding pocket of Fyn SH2 domain led to the identification of novel SH2 superbinders

Protein engineering through directed evolution is an effective way to obtain proteins with novel functions with the potential applications as tools for diagnosis or therapeutics. Many natural proteins have undergone directed evolution in vitro in the test tubes in the laboratories worldwide, resulting in the numerous protein variants with novel or enhanced functions. we constructed here an SH2 variant library by randomizing 8 variable residues in its phosphotyrosine (pTyr) binding pocket. Selection of this library by a pTyr peptide led to the identification of SH2 variants with enhanced affinities measured by EC50. Fluorescent polarization was then applied to quantify the binding affinities of the newly identified SH2 variants. As a result, three SH2 variants, named V3, V13 and V24, have comparable binding affinities with the previously identified SH2 triple-mutant superbinder. Biolayer Interferometry assay was employed to disclose the kinetics of the binding of these SH2 superbinders to the phosphotyrosine peptide. The results indicated that all the SH2 superbinders have two-orders increase of the dissociation rate when binding the pTyr peptide while there was no significant change in their associate rates. Intriguingly, though binding the pTyr peptide with comparable affinity with other SH2 superbinders, the V3 does not bind to the sTyr peptide. However, variant V13 and V24 have cross-reactivity with both pTyr and sTyr peptides. The newly identified superbinders could be utilized as tools for the identification of pTyr-containing proteins from tissues under different physiological or pathophysiological conditions and may have the potential in the therapeutics.

Matrine inhibits the development and progression of ovarian cancer by repressing cancer associated phosphorylation signaling pathways

Ovarian cancer remains the most lethal gynecologic malignancy with late detection and acquired chemoresistance. Advanced understanding of the pathophysiology and novel treatment strategies are urgently required. A growing body of proteomic investigations suggest that phosphorylation has a pivotal role in the regulation of ovarian cancer associated signaling pathways. Matrine has been extensively studied for its potent anti-tumor activities. However, its effect on ovarian cancer cells and underlying molecular mechanisms remain unclear. Herein we showed that matrine treatment inhibited the development and progression of ovarian cancer cells by regulating proliferation, apoptosis, autophagy, invasion and angiogenesis. Matrine treatment retarded the cancer associated signaling transduction by decreasing the phosphorylation levels of ERK1/2, MEK1/2, PI3K, Akt, mTOR, FAK, RhoA, VEGFR2, and Tie2 in vitro and in vivo. Moreover, matrine showed excellent antitumor effect on chemoresistant ovarian cancer cells. No obvious toxic side effects were observed in matrine-administrated mice. As the natural agent, matrine has the potential to be the targeting drug against ovarian cancer cells with the advantages of overcoming the chemotherapy resistance and decreasing the toxic side effects.

miR-4739 mediates pleural fibrosis by targeting bone morphogenetic protein 7

BACKGROUND

Pleural fibrosis is defined as excessive depositions of matrix components that result in pleural tissue architecture destruction and dysfunction. In severe cases, the progression of pleural fibrosis leads to lung entrapment, resulting in dyspnea and respiratory failure. However, the mechanism of pleural fibrosis is poorly understood.

METHODS

miR-4739 levels were detected by miRNA array and real-time PCR. Real-time PCR, western blotting and immunofluorescence were used to identify the expression profile of indicators related to fibrosis. Target gene of miR-4739 and promoter activity assay was measured by using dual-luciferase reporter assay system. In vivo, pleural fibrosis was evaluated by Masson staining and miR-4739 level was detected by In situ hybridization histochemistry.

FINDINGS

We found that bleomycin induced up-regulation of miR-4739 in pleural mesothelial cells (PMCs). Over-regulated miR-4739 mediated mesothelial-mesenchymal transition and increased collagen-I synthesis in PMCs. Investigation on the clinical specimens revealed that high levels of miR-4739 and low levels of bone morphogenetic protein 7 (BMP-7) associated with pleural fibrosis in patients. Then we next identified that miR-4739 targeted and down-regulated BMP-7 which further resulted in unbalance between Smad1/5/9 and Smad2/3 signaling. Lastly, in vivo studies revealed that miR-4739 over-expression induced pleural fibrosis, and exogenous BMP-7 prevented pleural fibrosis in mice.

INTERPRETATION

Our data indicated that miR-4739 targets BMP-7 which mediates pleural fibrosis. The miR-4739/BMP-7 axis is a promising therapeutic target for the disease. FUND: The National Natural Science Foundation of China.

[Design and synthesis of imidazo-fused heterocycles derivatives and their anti-tumor activity against breast cancer in mice]

OBJECTIVE

To synthesize compounds based on imidazo-fused heterocycles and evaluate their anti-tumor activity against breast cancer.

METHODS

The compounds 1a-1e, 2a and 2b were synthesized by aerobic copper-catalyzed halocyclization of methyl N-heteroaromatics with aliphatic amines; 3a and 3b were generated by sonogashira reaction and Suzuki reaction, respectively; the compounds 4a-4c were obtained by Buchwald-Hartwig reaction of the corresponding amines and 1e. The effects of these compounds against breast cancer cells and their nephrotoxicity were determined using MTT assay. Annexin VFITC/PI apoptosis detection kit was used to assess the apoptosis-inducing effects of these compounds in breast cancer cells. With normal saline as the control, the safety and anti-tumor activity of the compound 2a (daily dose of 10 mg/kg for 14 days) was tested in a mouse model bearing human breast cancer xenografts.

RESULTS

The compounds 2a, 4a, 4b and 4c all showed obvious anti-tumor activities. Among these compounds, 2a showed the most potent anti-tumor effect against breast cancer cells with an IC₅₀ of 9.77 ± 2.32 μmol/L, similar to that of cisplatin (IC₅₀=8.96 ± 2.35 μmol/L); 2a also showed a slightly lower nephrotoxicity than cisplatin, and their CC₅₀ was 10.79±0.87 μmol/L and 8.45±0.68 μmol/L, respectively. 2a obviously promoted apoptosis of breast cancer cells in vitro and caused a moderate suppression of the breast cancer growth in the tumor-bearing mouse models without producing serious adverse effects.

CONCLUSIONS

Four compounds synthesized based on imidazo-fused heterocycles have anti-tumor activities against breast cancer. The compound 2a is capable of dose-dependently promoting apoptosis of breast cancer cells in vitro and has a good safety and a moderate efficacy for suppressing tumor growth in mouse models bearing human breast cancer xenografts.

N-acetylcysteine decreases malignant characteristics of glioblastoma cells by inhibiting Notch2 signaling

BACKGROUND

Glioblastomas multiforme (GBM) is the most devastating primary intracranial malignancy lacking effective clinical treatments. Notch2 has been established to be a prognostic marker and probably involved in GBM malignant progression. N-acetylcysteine (NAC), a precursor of intracellular glutathione (GSH), has been widely implicated in prevention and therapy of several cancers. However, the role of NAC in GBM remains unclear and the property of NAC independent of its antioxidation is largely unknown.

METHODS

The mRNA and protein levels of Notch family and other related factors were detected by RT-PCR and western blot, respectively. In addition, intracellular reactive oxygen species (ROS) was measured by flow cytometry-based DCFH-DA. Moreover, cell viability was assessed by CCK8 and cell cycle was analyzed by flow cytometry-based PI staining. The level of apoptosis was checked by flow cytometry-based Annexin V/PI. Cell migration and invasion were evaluated by wound healing and transwell invasion assays. At last, U87 Xenograft model was established to confirm whether NAC could restrain the growth of tumor.

RESULTS

Our data showed that NAC could decrease the protein level of Notch2. Meanwhile, NAC had a decreasing effect on the mRNA and protein levels of its downstream targets Hes1 and Hey1. These effects caused by NAC were independent of cellular GSH and ROS levels. The mechanism of NAC-mediated Notch2 reduction was elucidated by promoting Notch2 degradation through Itch-dependent lysosome pathway. Furthermore, NAC could prevent proliferation, migration, and invasion and might induce apoptosis in GBM cells via targeting Notch2. Significantly, NAC could suppress the growth of tumor in vivo.

CONCLUSIONS

NAC could facilitate Notch2 degradation through lysosomal pathway in an antioxidant-independent manner, thus attenuating Notch2 malignant signaling in GBM cells. The remarkable ability of NAC to inhibit cancer cell proliferation and tumor growth may implicate a novel application of NAC on GBM therapy.

1988-2018: Thirty years of drug smuggling at the nano scale. Challenges and opportunities of cell-penetrating peptides in biomedical research

In 1988, two unrelated papers reported the discovery of peptide vectors with innate cell translocation properties, setting the ground for a new area of research that over the years has grown into considerable therapeutic potential. The vectors, named cell-penetrating peptides (CPPs), constitute a now large and diversified family, sharing the extraordinary ability to diffuse unaltered across cell membranes while ferrying diverse associated cargos. Such properties have made CPPs ideal tools for delivery of nucleic acids, proteins and other therapeutic/diagnostic molecules to cells and tissues via covalent conjugation or complexation. This year 2018 marks the 30^th anniversary of a peptide research landmark opening new perspectives in drug delivery. Given its vastness, exhaustive coverage of the main features and accomplishments in the CPP field is virtually impossible. Hence this manuscript, after saluting the above 30^th jubilee, focuses by necessity on the most recent contributions, providing a comprehensive list of recognized CPPs and their latest-reported applications over the last two years. In addition, it thoroughly reviews three areas of peptide vector research of particular interest to us, namely (i) efficient transport of low-bioavailability drugs into the brain; (ii) CPP-delivered disruptors of G protein-coupled receptor (GPCRs) heteromers related to several disorders, and (iii) CPP-mediated delivery of useful but poorly internalized drugs into parasites.