Exploring the therapeutic potential of DV-B-120 as an inhibitor of dengue virus infection.

Dengue fever, an infectious disease prevalent in subtropical and tropical regions, currently lacks effective small-molecule drugs as treatment. In this study, we used a fluorescence peptide cleavage assay to screen seven compounds to assess their inhibition of the dengue virus (DENV) NS2B-NS3 protease. DV-B-120 demonstrated superior inhibition of NS2B-NS3 protease activity and lower toxicity compared to ARDP0006. The selectivity index of DV-B-120 was higher than that of ARDP0006. In vivo assessments of the antiviral efficacy of DV-B-120 against DENV replication demonstrated delayed mortality of suckling mice treated with the compound, with 60-80% protection against life-threatening effects, compared to the outcomes of DENV-infected mice treated with saline. The lower clinical scores of DENV-infected mice treated with DV-B-120 indicated a reduction in acute-progressive illness symptoms, underscoring the potential therapeutic impact of DV-B-120. Investigations of DV-B-120's ability to restore the antiviral type I IFN response in the brain tissue of DENV-infected ICR suckling mice demonstrated its capacity to stimulate IFN and antiviral IFN-stimulated gene expression. DV-B-120 not only significantly delayed DENV-2-induced mortality and illness symptoms but also reduced viral numbers in the brain, ultimately restoring the innate antiviral response. These findings strongly suggest that DV-B-120 holds promise as a therapeutic agent against DENV infection and highlight its potential contribution in addressing the current lack of effective treatments for this infectious disease.IMPORTANCEThe prevalence of dengue virus (DENV) infection in tropical and subtropical regions is escalating due to factors like climate change and mosquito vector expansion. With over 300 million annual infections and potentially fatal outcomes, the urgent need for effective treatments is evident. While the approved Dengvaxia vaccine has variable efficacy, there are currently no antiviral drugs for DENV. This study explores seven compounds targeting the NS2B-NS3 protease, a crucial protein in DENV replication. These compounds exhibit inhibitory effects on DENV-2 NS2B-NS3, holding promise for disrupting viral replication and preventing severe manifestations. However, further research, including animal testing, is imperative to assess therapeutic efficacy and potential toxicity. Developing safe and potent treatments for DENV infection is critical in addressing the rising global health threat posed by this virus.

Specific activation of pro-Infliximab enhances selectivity and safety of rheumatoid arthritis therapy.

During rheumatoid arthritis (RA) treatment, long-term injection of antitumor necrosis factor α antibodies (anti-TNFα Abs) may induce on-target toxicities, including severe infections (tuberculosis [TB] or septic arthritis) and malignancy. Here, we used an immunoglobulin G1 (IgG1) hinge as an Ab lock to cover the TNFα-binding site of Infliximab by linking it with matrix metalloproteinase (MMP) -2/9 substrate to generate pro-Infliximab that can be specifically activated in the RA region to enhance the selectivity and safety of treatment. The Ab lock significantly inhibits the TNFα binding and reduces the anti-idiotypic (anti-Id) Ab binding to pro-Infliximab by 395-fold, 108-fold compared with Infliximab, respectively, and MMP-2/9 can completely restore the TNFα neutralizing ability of pro-Infliximab to block TNFα downstream signaling. Pro-Infliximab was only selectively activated in the disease site (mouse paws) and presented similar pharmacokinetics (PKs) and bio-distribution to Infliximab. Furthermore, pro-Infliximab not only provided equivalent therapeutic efficacy to Infliximab but also maintained mouse immunity against Listeria infection in the RA mouse model, leading to a significantly higher survival rate (71%) than that of the Infliximab treatment group (0%). The high-selectivity pro-Infliximab maintains host immunity and keeps the original therapeutic efficiency, providing a novel strategy for RA therapy.

Inhibition of gut microbial ß-glucuronidase effectively prevents carcinogen-induced microbial dysbiosis and intestinal tumorigenesis.

The bidirectional interaction between carcinogens and gut microbiota that contributes to colorectal cancer is complicated. Reactivation of carcinogen metabolites by microbial ß-glucuronidase (ßG) in the gut potentially plays an important role in colorectal carcinogenesis. We assessed the chemoprotective effects and associated changes in gut microbiota induced by pre-administration of bacterial-specific ßG inhibitor TCH-3511 in carcinogen azoxymethane (AOM)-treated APCMin/+ mice. AOM induced intestinal ßG activity, which was reflected in increases in the incidence, formation, and number of tumors in the intestine. Notably, inhibition of gut microbial ßG by TCH-3511 significantly reduced AOM-induced intestinal ßG activity, decreased the number of polyps in both the small and large intestine to a frequency that was similar in mice without AOM exposure. AOM also led to lower diversity and altered composition in the gut microbiota with a significant increase in mucin-degrading Akkermansia genus. Conversely, mice treated with TCH-3511 and AOM exhibited a more similar gut microbiota structure as mice without AOM administration. Importantly, TCH-3511 treatment significant decreased Akkermansia genus and produced a concomitant increase in short-chain fatty acid butyrate-producing gut commensal microbes Lachnoospiraceae NK4A136 group genus in AOM-treated mice. Taken together, our results reveal a key role of gut microbial ßG in promoting AOM-induced gut microbial dysbiosis and intestinal tumorigenesis, indicating the chemoprotective benefit of gut microbial ßG inhibition against carcinogens via maintaining the gut microbiota balance and preventing cancer-associated gut microbial dysbiosis. Thus, the bacterial-specific ßG inhibitor TCH-3511 is a potential chemoprevention agent for colorectal cancer.

Ab locks for improving the selectivity and safety of antibody drugs.

Monoclonal antibodies (mAbs) are a major targeted therapy for malignancies, infectious diseases, autoimmune diseases, transplant rejection and chronic inflammatory diseases due to their antigen specificity and longer half-life than conventional drugs. However, long-term systemic antigen neutralization by mAbs may cause severe adverse events. Improving the selectivity of mAbs to distinguish target antigens at the disease site from normal healthy tissue and reducing severe adverse events caused by the mechanisms-of-action of mAbs is still a pressing need. Development of pro-antibodies (pro-Abs) by installing a protease-cleavable Ab lock is a novel and advanced recombinant Ab-based strategy that efficiently masks the antigen binding ability of mAbs in the normal state and selectively "turns on" the mAb activity when the pro-Ab reaches the proteolytic protease-overexpressed diseased tissue. In this review, we discuss the design and advantages/disadvantages of different Ab lock strategies, focusing particularly on spatial-hindrance-based and affinity peptide-based approaches. We expect that the development of different masking strategies for mAbs will benefit the local reactivity of mAbs at the disease site, increase the therapeutic efficacy and safety of long-term treatment with mAbs in chronic diseases and even permit scientists to develop Ab drugs for formerly undruggable targets and satisfy the unmet medical needs of mAb therapy.

Optimization of an Anti-poly(ethylene glycol) (anti-PEG) Cell-Based Capture System To Quantify PEG and PEGylated Molecules.

Sensitive determination of the pharmacokinetics of PEGylated molecules can accelerate the process of drug development. Here, we combined different anti-PEG Fab expressing 293T cells as capture cells (293T/3.3, 293T/6.3, and 293T/15-2b cells) with four detective anti-PEG antibodies (3.3, 6.3, 7A4, or 15-2b) to optimize an anti-PEG cell-based sandwich ELISA. Then, we quantified free PEG (mPEG2K-NH2 and mPEG5K-NH2) or PEG-conjugated small molecules (mPEG5K-biotin and mPEG5K-NIR797), proteins (PegIntron and Pegasys), and nanoparticles (Liposomal-Doxorubicin and quantum-dots). The combination of 293T/15-2b cells and the 7A4 detection antibody was best sensitivity for free PEG, PEG-like molecules, and PEGylated proteins with detection at ng mL-1 levels. On the other hand, 293T/3.3 cells combined with the 15-2b antibody had the highest sensitivity for quantifying Lipo-Dox at 2 ng mL-1. All three types of anti-PEG cells combined with the 15-2b antibody had high sensitivity for quantum dot quantification down to 7 pM. These results suggest that the combination of 293T/15-2b cells and 7A4 detection antibody is the optimal pair for sensitive quantification of free PEG, PEG-like molecules, and PEGylated proteins, whereas the 293T/3.3 cells combined with 15-2b are more suitable for quantifying PEGylated nanoparticles. The optimized anti-PEG cell-based sandwich ELISA can provide a sensitive, precise, and convenient tool for the quantification of a range of PEGylated molecules.

Discovery of specific inhibitors for intestinal E. coli ß-glucuronidase through in silico virtual screening.

Glucuronidation is a major metabolism process of detoxification for carcinogens, 4-(methylnitrosamino)-1-(3-pyridy)-1-butanone (NNK) and 1,2-dimethylhydrazine (DMH), of reactive oxygen species (ROS). However, intestinal E. coli ß-glucuronidase (eßG) has been considered pivotal to colorectal carcinogenesis. Specific inhibition of eßG may prevent reactivating the glucuronide-carcinogen and protect the intestine from ROS-mediated carcinogenesis. In order to develop specific eßG inhibitors, we found that 59 candidate compounds obtained from the initial virtual screening had high inhibition specificity against eßG but not human ßG. In particular, we found that compounds 7145 and 4041 with naphthalenylidene-benzenesulfonamide (NYBS) are highly effective and selective to inhibit eßG activity. Compound 4041 (IC50 = 2.8 µM) shows a higher inhibiting ability than compound 7145 (IC50 = 31.6 µM) against eßG. Furthermore, the molecular docking analysis indicates that compound 4041 has two hydrophobic contacts to residues L361 and I363 in the bacterial loop, but 7145 has one contact to L361. Only compound 4041 can bind to key residue (E413) at active site of eßG via hydrogen-bonding interactions. These novel NYBS-based eßG specific inhibitors may provide as novel candidate compounds, which specifically inhibit eßG to reduce eßG-based carcinogenesis and intestinal injury.

Discovery of Akt kinase inhibitors through structure-based virtual screening and their evaluation as potential anticancer agents.

Akt acts as a pivotal regulator in the PI3K/Akt signaling pathway and represents a potential drug target for cancer therapy. To search for new inhibitors of Akt kinase, we performed a structure-based virtual screening using the DOCK 4.0 program and the X-ray crystal structure of human Akt kinase. From the virtual screening, 48 compounds were selected and subjected to the Akt kinase inhibition assay. Twenty-six of the test compounds showed more potent inhibitory effects on Akt kinase than the reference compound, H-89. These 26 compounds were further evaluated for their cytotoxicity against HCT-116 human colon cancer cells and HEK-293 normal human embryonic kidney cells. Twelve compounds were found to display more potent or comparable cytotoxic activity compared to compound H-89 against HCT-116 colon cancer cells. The best results were obtained with Compounds a46 and a48 having IC50 values (for HCT-116) of 11.1 and 9.5 µM, respectively, and selectivity indices (IC50 for HEK-293/IC50 for HCT-116) of 12.5 and 16.1, respectively. Through structure-based virtual screening and biological evaluations, we have successfully identified several new Akt inhibitors that displayed cytotoxic activity against HCT-116 human colon cancer cells. Especially, Compounds a46 and a48 may serve as useful lead compounds for further development of new anticancer agents.

Selective activation of IFNγ-ipilimumab enhances the therapeutic effect and safety of ipilimumab.

INTRODUCTION: Immune checkpoint inhibitor therapy is a highly promising strategy for clinical treatment of cancer. Among these inhibitors, ipilimumab stands out for its ability to induce cytotoxic T cell proliferation and activation by binding to CTLA-4. However, ipilimumab also gives rise to systemic immune-related adverse effects and tumor immune evasion, limiting its effectiveness. OBJECTIVES: We developed IFNγ-ipilimumab and confirmed that the addition of INF-γ does not alter the fundamental properties of ipilimumab. RESULTS: IFNγ-ipilimumab can be activated by matrix metalloproteinases, thereby promoting the IFNγ signaling pathway and enhancing the cytotoxicity of T cells. In vivo studies demonstrated that IFNγ-ipilimumab enhances the therapeutic effect of ipilimumab against colorectal cancer by increasing CD8+ and CD4+ lymphocyte infiltration into the tumor area and inducing MHC-I expression in tumor cells. Mice treated with IFNγ-ipilimumab showed higher survival rates and body weight, as well as lower CD4+ and CD8+ lymphocyte activation rates in the blood and reduced organ damage. CONCLUSION: IFNγ-ipilimumab improved the effectiveness of ipilimumab while reducing its side effects. It is likely that future immunotherapies would rely on such antibodies to activate local cancer cells or immune cells, thereby increasing the therapeutic effectiveness of cancer treatments and ensuring their safety.

Sensitivity of PEGylated interferon detection by anti-polyethylene glycol (PEG) antibodies depends on PEG length.

Attachment of poly(ethylene glycol) to proteins can mask immune epitopes to increase serum half-life, reduce immunogenicity, and enhance in vivo biological efficacy. However, PEGylation mediated epitope-masking may also limit sensitivity and accuracy of traditional ELISA. We previously described an anti-PEG-based sandwich ELISA for universal assay of PEGylated molecules. Here, we compared the quantitative assessment of PEGylated interferons by anti-PEG and traditional anti-interferon sandwich ELISA. The detection limits for PEG-Intron (12k-PEG) and Pegasys (40k-PEG) were 1.9 and 0.03 ng/mL for anti-PEG ELISA compared to 0.18 and 0.42 ng/mL for traditional anti-interferon sandwich ELISA. These results indicate that the anti-PEG sandwich ELISA was insensitive to PEGylation mediated epitope-masking and the sensitivity increased in proportion to the length of PEG. By contrast, PEG-masking interfered with detection by traditional anti-interferon sandwich ELISA. Human and mouse serum did not affect the sensitivity of anti-PEG ELISA but impeded traditional anti-interferon sandwich ELISA. The anti-PEG sandwich ELISA was comparable to anti-interferon sandwich ELISA and radioassay of 131I-Pegasys in pharmacokinetic studies in mice. The anti-PEG sandwich ELISA provides a sensitive, accurate, and convenient quantitative measurement of PEGylated protein drugs.

XPF-ERCC1 Blocker Improves the Therapeutic Efficacy of 5-FU- and Oxaliplatin-Based Chemoradiotherapy in Colorectal Cancer.

5-FU-based chemoradiotherapy (CRT) and oxaliplatin-based CRT are commonly used therapies for advanced colorectal cancer (CRC). However, patients with a high expression of ERCC1 have a worse prognosis than those with a low expression. In this study, we investigated the effect of XPF-ERCC1 blockers on chemotherapy and 5-FU-based CRT and oxaliplatin (OXA)-based CRT in colorectal cancer cell lines. We investigated the half-maximal inhibitory concentration (IC50) of 5-FU, OXA, XPF-ERCC1 blocker, and XPF-ERCC1 blocker, and 5-FU or OXA combined and analyzed the effect of XPF-ERCC1 blocker on 5-FU-based CRT and oxaliplatin-based CRT. Furthermore, the expression of XPF and γ-H2AX in colorectal cells was analyzed. In animal models, we combined the XPF-ERCC1 blocker with 5-FU and OXA to investigate the effects of RC and finally combined the XPF-ERCC1 blocker with 5-FU- and oxaliplatin-based CRT. In the IC50 analysis of each compound, the cytotoxicity of the XPF-ERCC1 blocker was lower than that of 5-FU and OXA. In addition, the XPF-ERCC1 blocker combined with 5-FU or OXA enhanced the cytotoxicity of the chemotherapy drugs in colorectal cells. Furthermore, the XPF-ERCC1 blocker also increased the cytotoxicity of 5-FU-based CRT and OXA -based CRT by inhibiting the XPF product DNA locus. In vivo, the XPF-ERCC1 blocker was confirmed to enhance the therapeutic efficacy of 5-FU, OXA, 5-FU-based CRT, and OXA CRT. These findings show that XPF-ERCC1 blockers not only increase the toxicity of chemotherapy drugs but also increase the efficacy of combined chemoradiotherapy. In the future, the XPF-ERCC1 blocker may be used to improve the efficacy of 5-FU- and oxaliplatin-based CRT.

Development of NS2B-NS3 protease inhibitor that impairs Zika virus replication.

Zika virus (ZIKV) is a mosquito-borne flavivirus that causes severe neurological disorders, such as microcephaly in fetuses. Most recently, an outbreak of ZIKV started in Brazil in 2015. To date, no therapeutic agents have been approved to treat ZIKV infection in the clinic. Here, we screened a small molecule inhibitor that can inhibit the function of ZIKV non-structural protein 2B (NS2B)-NS3 protease (ZIKV NS2B-NS3 protease), thereby interfering with viral replication and spread. First, we identified the half maximal inhibitory concentration (IC50) of compound 3 (14.01 µM), 8 (6.85 µM), and 9 (14.2 µM) and confirmed that they are all non-competitive inhibitors. In addition, we have used the blind molecular docking method to simulate the inhibition area of three non-competitive inhibitors (compound 3, 8, and 9) with the ZIKV NS2B-NS3 protease. The results indicated that the four allosteric binding residues (Gln139, Trp148, Leu150, and Val220) could form hydrogen bonds or non-bonding interactions most frequently with the three compounds. The interaction might induce the reaction center conformation change of NS2B-NS3 protease to reduce catalyzed efficiency. The concentration of compounds required to reduce cell viability by 50% (CC50), and the concentration of compounds required to inhibit virus-induced cytopathic effect by 50% (EC50) of three potential compounds are >200 µM, 2.15 µM (compound 3), > 200 µM, 0.52 µM (compound 8) and 61.48 µM, 3.52 µM (compound 9), and Temoporfin are 61.05 µM, 2 µM, respectively. To select candidate compounds for further animal experiments, we analyzed the selectivity index (SI) of compound 3 (93.02), 8 (384.61), 9 (17.46), and Temoporfin (30.53, FDA-approved drug against cancer). Compound 8 has the highest SI value. Therefore, compound 8 was selected for verification in animal models. In vivo, compound 8 significantly delayed ZIKV-induced lethality and illness symptoms and decreased ZIKV-induced weight loss in a ZIKV-infected suckling mouse model. We conclude that compound 8 is worth further investigation for use as a potential future therapeutic agent against ZIKV infection.

An activity-based near-infrared glucuronide trapping probe for imaging ß-glucuronidase expression in deep tissues.

ß-glucuronidase is an attractive reporter and prodrug-converting enzyme. The development of near-IR (NIR) probes for imaging of ß-glucuronidase activity would be ideal to allow estimation of reporter expression and for personalized glucuronide prodrug cancer therapy in preclinical studies. However, NIR glucuronide probes are not yet available. In this work, we developed two fluorescent probes for detection of ß-glucuronidase activity, one for the NIR range (containing IR-820 dye) and the other for the visible range [containing fluorescein isothiocyanate (FITC)], by utilizing a difluoromethylphenol-glucuronide moiety (TrapG) to trap the fluorochromes in the vicinity of the active enzyme. ß-glucuronidase-mediated hydrolysis of the glucuronyl bond of TrapG generates a highly reactive alkylating group that facilitates the attachment of the fluorochrome to nucleophilic moieties located near ß-glucuronidase-expressing sites. FITC-TrapG was selectively trapped on purified ß-glucuronidase or ß-glucuronidase-expressing CT26 cells (CT26/mßG) but not on bovine serum albumin or non-ß-glucuronidase-expressing CT26 cells used as controls. ß-glucuronidase-activated FITC-TrapG did not interfere with ß-glucuronidase activity and could label bystander proteins near ß-glucuronidase. Both FITC-TrapG and NIR-TrapG specifically imaged subcutaneous CT26/mßG tumors, but only NIR-TrapG could image CT26/mßG tumors transplanted deep in the liver. Thus NIR-TrapG may provide a valuable tool for visualizing ß-glucuronidase activity in vivo.

A regularly spaced and self-revealing protein ladder for anti-tag Western blot analysis.

We designed a protein ladder (hereafter referred to as "Mega-tag") that contains 14 of the most commonly used epitope tags fused to molecular weight markers. The Mega-tag ladder can be simultaneously visualized when anti-tag antibodies are used to detect epitope-tagged recombinant proteins in Western blots. The logarithm of molecular weights and relative mobility of the Mega-tag protein ladder are highly correlated (R(2)=0.997±0.00232), indicating that the dye-free Mega-tag protein ladder is accurate. It can also serve as a positive control for anti-epitope tag immunoblots. The Mega-tag protein ladder should provide a convenient and precise tool for Western blot analysis.

Evaluation of Clove Extract for Drug Therapy of Ciliate Infection in Coral (Goniopora columna).

In recent years, ciliate infections have caused serious casualties to corals in the ocean. Infected corals die within a short period of time, which not only poses a threat to wild coral reefs, but also has a major impact on large scale aquaculture of coral. Clove is a kind of Chinese medicine with antifungal, antibacterial, antiviral, insecticidal, and other functions. Clove is a natural product. If it can be used in the treatment of coral ciliates, it will reduce this threat to the environment. The clove extract was diluted with sterile seawater to 500 ppm, 1500 ppm, 2500 ppm, 5000 ppm, 7500 ppm, and 10,000 ppm to carry out virulence test on ciliates. The results show that the LC50 value is 1500 ppm, which can cause the death of ciliates in 10 min without causing significant changes in G. columna SOD, CAT, chlorophyll a, and zooxanthellae. In addition, observation of tissue slices revealed that no ciliates and vacuum were found in the G. columna tissue after 10 min of medicated bathing. In summary, 1500 ppm of clove extract can be used for the treatment of coral ciliates.

ERCC1 Overexpression Increases Radioresistance in Colorectal Cancer Cells.

Preoperative concurrent chemoradiotherapy (CCRT) is a standard treatment for locally advanced rectal cancer patients, but 20-30% do not benefit from the desired therapeutic effects. Previous reports indicate that high levels of ERCC1 reduce the effectiveness of cisplatin-based CCRT; however, it remains unclear as to whether ERCC1 overexpression increases radiation resistance. To clarify the correlation between ERCC1 levels and radiation (RT) resistance, we established two cell lines (HCT116-Tet-on and COLO205-Tet-on), induced them to overexpress ERCC1, detected cell survival following exposure to radiation, established HCT116-Tet-on and COLO205-Tet-on heterotopic cancer animal models, and detected tumor volume following exposure to radiation. We found that ERCC1 overexpression increased radiation resistance. After regulating ERCC1 levels and radiation exposure to verify the correlation, we noted that increased radiation resistance was dependent on ERCC1 upregulation in both cell lines. For further verification, we exposed HCT116-Tet-on and COLO205-Tet-on heterotopic cancer animal models to radiation and observed that ERCC1 overexpression increased colorectal cancer tumor radioresistance in both. Combined, our results suggest that ERCC1 overexpression may serve as a suitable CCRT prognostic marker for colorectal cancer patients.

HIF-1α Expression Increases Preoperative Concurrent Chemoradiotherapy Resistance in Hyperglycemic Rectal Cancer.

Purpose: Preoperative concurrent chemoradiotherapy (CCRT) is the standard treatment for locally advanced rectal cancer patients. However, the poor therapeutic efficacy of CCRT was found in rectal cancer patients with hyperglycemia. This study investigated how hyperglycemia affects radiochemotherapy resistance in rectal cancer. Methods and Materials: We analyzed the correlation between prognosis indexes with hypoxia-inducible factor-1 alpha (HIF-1α) in rectal cancer patients with preoperative CCRT. In vitro, we investigated the effect of different concentrated glucose of environments on the radiation tolerance of rectal cancers. Further, we analyzed the combined HIF-1α inhibitor with radiation therapy in hyperglycemic rectal cancers. Results: The prognosis indexes of euglycemic or hyperglycemic rectal cancer patients after receiving CCRT treatment were investigated. The hyperglycemic rectal cancer patients (n = 13, glycosylated hemoglobin, HbA1c > 6.5%) had poorer prognosis indexes. In addition, a positive correlation was observed between HIF-1α expression and HbA1c levels (p = 0.046). Therefore, it is very important to clarify the relationship between HIF-1α and poor response in patients with hyperglycemia receiving pre-operative CCRT. Under a high glucose environment, rectal cancer cells express higher levels of glucose transport 1 (GLUT1), O-GlcNAc transferase (OGT), and HIF-1α, suggesting that the high glucose environment might stimulate HIF-1α expression through the GLUT1-OGT-HIF-1α pathway promoting tolerance to Fluorouracil (5-FU) and radiation. In the hyperglycemic rectal cancer animal model, rectal cancer cells confirmed that radiation exposure reduces apoptosis by overexpressing HIF-1α. Combining HIF-1α inhibitors was able to reverse radioresistance in a high glucose environment. Lower HIF-1α levels increased DNA damage in tumors leading to apoptosis. Conclusions: The findings here show that hyperglycemia induces the expression of GLUT1, OGT, and HIF-1α to cause CCRT tolerance in rectal cancer and suggest that combining HIF-1α inhibitors could reverse radioresistance in a high glucose environment. HIF-1α inhibitors may be useful for development as CCRT sensitizers in patients with hyperglycemic rectal cancer.

Micro-PET imaging of hepatitis C virus NS3/4A protease activity using a protease-activatable retention probe.

Hepatitis C virus (HCV) NS3/4A protease is an attractive target for direct-acting antiviral agents. Real-time tracking of the NS3/4A protease distribution and activity is useful for clinical diagnosis and disease management. However, no approach has been developed that can systemically detect NS3/4A protease activity or distribution. We designed a protease-activatable retention probe for tracking HCV NS3/4A protease activity via positron emission topography (PET) imaging. A cell-penetrating probe was designed that consisted of a cell-penetrating Tat peptide, HCV NS3/4A protease substrate, and a hydrophilic domain. The probe was labeled by fluorescein isothiocyanate (FITC) and 124I in the hydrophilic domain to form a TAT-ΔNS3/4A-124I-FITC probe. Upon cleavage at NS3/4A substrate, the non-penetrating hydrophilic domain is released and accumulated in the cytoplasm allowing PET or optical imaging. The TAT-ΔNS3/4A-FITC probe selectively accumulated in NS3/4A-expressing HCC36 (NS3/4A-HCC36) cells/tumors and HCV-infected HCC36 cells. PET imaging showed that the TAT-ΔNS3/4A-124I-FITC probe selectively accumulated in the NS3/4A-HCC36 xenograft tumors and liver-implanted NS3/4A-HCC36 tumors, but not in the control HCC36 tumors. The TAT-ΔNS3/4A-124I-FITC probe can be used to represent NS3/4 protease activity and distribution via a clinical PET imaging system allowing. This strategy may be extended to detect any cellular protease activity for optimization the protease-based therapies.

Improved skin permeability and whitening effect of catechin-loaded transfersomes through topical delivery.

The aim of the study was to prepare catechin-loaded transfersomes to enhance drug permeability through topical administration for the skin protection against ultraviolet radiation induced photo-damage. The results showed that the catechin-loaded transfersomes were monodispersed with polydispersity index (PDI) < 0.2, <200 nm in particle size and with high encapsulation efficiency (E.E.%) greater than 85%. The in vitro skin permeation test indicated that the catechin-loaded transfersomes enhanced the skin permeability by 85% compared to the catechin aqueous solution. Similarly, the in-vivo skin whitening study demonstrated that F5 transfersome formulation was effective in tyrosinase inhibition and had good biocompatibility to the guinea pig skin. Finally, the stability study showed that both physicochemical properties and E.E.% of the F5 transferosome formulation were fairly stable after 3 months storage. Therefore, topical administration of catechin-loaded transfersomes could be considered as a potential strategy for the treatment of UV-induced oxidative damage to the skin.

Correction: Development of a structure-based computational simulation to optimize the blocking efficacy of pro-antibodies.

[This corrects the article DOI: 10.1039/D1SC01748A.].

Development of a structure-based computational simulation to optimize the blocking efficacy of pro-antibodies.

The on-target toxicity of monoclonal antibodies (Abs) is mainly due to the fact that Abs cannot distinguish target antigens (Ags) expressed in disease regions from those in normal tissues during systemic administration. In order to overcome this issue, we "copied" an autologous Ab hinge as an "Ab lock" and "pasted" it on the binding site of the Ab by connecting a protease substrate and linker in between to generate a pro-Ab, which can be specifically activated in the disease region to enhance Ab selectivity and reduce side effects. Previously, we reported that 70% of pro-Abs can achieve more than 100-fold blocking ability compared to the parental Abs. However, 30% of pro-Abs do not have such efficient blocking ability. This is because the same Ab lock linker cannot be applied to every Ab due to the differences in the complementarity-determining region (CDR) loops. Here we designed a method which uses structure-based computational simulation (MSCS) to optimize the blocking ability of the Ab lock for all Ab drugs. MSCS can precisely adjust the amino acid composition of the linker between the Ab lock and Ab drug with the assistance of molecular simulation. We selected αPD-1, αIL-1ß, αCTLA-4 and αTNFα Ab as models and attached the Ab lock with various linkers (L1 to L7) to form pro-Abs by MSCS, respectively. The resulting cover rates of the Ab lock with various linkers compared to the Ab drug were in the range 28.33-42.33%. The recombinant pro-Abs were generated by MSCS prediction in order to verify the application of molecular simulation for pro-Ab development. The binding kinetics effective concentrations (EC-50) for αPD-1 (200-250-fold), αIL-1ß (152-186-fold), αCTLA-4 (68-150-fold) and αTNFα Ab (20-123-fold) were presented as the blocking ability of pro-Ab compared to the Ab drug. Further, there was a positive correlation between cover rate and blocking ability of all pro-Ab candidates. The results suggested that MSCS was able to predict the Ab lock linker most suitable for application to αPD-1, αIL-1ß, αCTLA-4 and αTNFα Ab to form pro-Abs efficiently. The success of MSCS in optimizing the pro-Ab can aid the development of next-generation pro-Ab drugs to significantly improve Ab-based therapies and thus patients' quality of life.