Targeting kelch-like (KLHL) proteins: achievements, challenges and perspectives.

Kelch-like proteins (KLHLs) are a large family of BTB-containing proteins. KLHLs function as the substrate adaptor of Cullin 3-RING ligases (CRL3) to recognize substrates. KLHLs play pivotal roles in regulating various physiological and pathological processes by modulating the ubiquitination of their respective substrates. Mounting evidence indicates that mutations or abnormal expression of KLHLs are associated with various human diseases. Targeting KLHLs is a viable strategy for deciphering the KLHLs-related pathways and devising therapies for associated diseases. Here, we comprehensively review the known KLHLs inhibitors to date and the brilliant ideas underlying their development.

Casitas b cell lymphoma­B (Cbl-b): A new therapeutic avenue for small-molecule immunotherapy.

Immunotherapy has revolutionized the area of cancer treatment. Although most immunotherapies now are antibodies targeting membrane checkpoint molecules, there is an increasing demand for small-molecule drugs that address intracellular pathways. The E3 ubiquitin ligase Casitas B cell lymphoma­b (Cbl-b) has been regarded as a promising intracellular immunotherapy target. Cbl-b regulates the downstream proteins of multiple membrane receptors and co-receptors, restricting the activation of the innate and adaptive immune system. Recently, Cbl-b inhibitors have been reported with promising effects on immune surveillance activation and anti-tumor efficacy. Several molecules have entered phase Ⅰ clinical trials. In this review, the biological rationale of Cbl-b as a promising target for cancer immunotherapy and the latest research progress of Cbl-b are summarized, with special emphasis on the allosteric small-molecule inhibitors of Cbl-b.

Deletion of RNF186 expression suppresses diet-induced hepatic steatosis by regulating insulin activity.

RING finger protein186 (RNF186) is dramatically upregulated in steatotic livers. The physiological role of RNF186 in non-alcoholic fatty liver disease (NAFLD) remains obscure. Here, we found that hepatocyte-specific RNF186 knockout (RNF186 LKO ) mice were protected from HFD-induced obesity. RNF186 ablation in liver suppressed inflammatory responses and ER stress and alleviated insulin tolerance, leading to improved glucose and lipid metabolism under HFD conditions. RNA-seq and western blot analyses revealed a significant downregulation of peroxisome proliferator-activated receptor γ, stearoyl-CoA desaturase 1, and cluster of differentiation 36 in the liver of RNF186 knockout mice consuming HFD. RNF186 deletion in liver results in less weight gain during HFD feeding and is associated with reduced liver fat, inflammation, and improved glucose and insulin tolerance. In contrast, upregulation of RNF186 in C57BL/6J mice livers impaired lipid metabolism and insulin tolerance. The collective results suggest that RNF186 may be a potential regulator of NAFLD in obesity.

An affinity prediction approach for the ligand of E3 ligase Cbl-b and an insight into substrate binding pattern.

Protein-protein interactions (PPIs) are essentially fundamental to all cellular processes, so that developing small molecule inhibitors of PPIs have great significance despite representing a huge challenge. Studying PPIs with the help of peptide motifs could obtain the structural information and reference significance to reduce the difficulty in the development of small molecules. Computational methods are powerful tools to characterize peptide-protein interactions, especially molecular dynamics simulation and binding free energy calculation. Here, we established an affinity prediction model suitable for Casitas B lymphoma-b (Cbl-b) and phosphorylated motif system. According to the affinity data set of multiple truncated peptides, the force field, solvent model, and internal dielectric constant of molecular mechanics/generalized Born surface area (MM/GBSA) method were optimized. Further, we predicted the affinity of the rationally designed new sequences through this model and obtained a new 6-mer motif with a 7-fold increase in affinity and the comprehensive structure-activity relationship. Moreover, we proposed an insight of unexpected activity of the truncated 5-mer peptide and revealed the possible binding mode of the new highly active 6-mer motif by extended simulation. Our results showed that the activity enhancement of the truncated peptide was caused by the acetyl-mediated conformation change. The side chain of Arg and pTyr in the 6-mer motif co-occupied the site p1 to form numerous hydrogen bond interactions and increased hydrophobic interaction formed with Tyr266, leading to the higher affinity. The present work provided a reference to investigate the PPI of Cbl-b and phosphorylated substrates and guided the development of Cbl-b inhibitors.

The role and mechanism of action of RNF186 in colorectal cancer through negative regulation of NF-κB.

Colorectal cancer (CRC) is one of the most common malignant gastrointestinal cancers worldwide. RING finger protein 186 (RNF186) is a member of the RING finger protein family. RNF186 has been reported to be involved in the regulation of the intestinal homeostasis through the regulation of endoplasmic reticulum (ER) stress in colonic epithelial cells. However, its role in CRC remains unclear. In this study, we found that colorectal tumours from human patients had decreased levels of RNF186. We demonstrated that overexpression of RNF186 suppressed the growth and migration of CRC-derived cell lines in vitro and inhibited tumour proliferation in vivo. Further, our findings indicated that forced expression of RNF186 inhibited nuclear factor-κB (NF-κB) activation by reducing the phosphorylation of NF-κB. In addition, our results showed that RNF186-/- mice exhibited significantly increased tumour burden compared to the wild type (WT) mice following treatment with azoxymethane/dextran sulfate sodium (AOM/DSS). Compared to WT mice, the percentage of Ki67 positive cells was increased in the RNF186-/- mice, indicating that RNF186 is crucial for intestinal cell proliferation during tumorigenesis. Taken together, our data suggest that RNF186 inhibits the development of CRC, and that this effect is mediated through the suppression of NF-κB activity.

[A study on clinical differential diagnosis between hemangioma and vascular malformation in infant].

OBJECTIVE: To explore the main points of clinical differentiation between hemangioma and vascular malformation in infant. METHODS: Based on Mulliken and Waner's classification, from March, 1997 to February, 1999, 81 baby patients with hemangioma were included in this study. Thirty-eight cases, 43 cases received medical treatment of steroids. RESULTS: All the patients were followed up from 5 to 7 years. Thirty-eight cases of red strawberry-like lesions limited in the skin began to involute within two years old. Of the 30 patients with strawberry-like lesions and subcutaneous mass, 20 cases involuted in varying degree; 10 cases' subcutaneous mass grew gradually and didn't involute, in 4 cases biopsy was performed, 3 cases were confirmed as hemangioma accompanied with venous malformation by pathology, 1 case was hemangioma accompanied with arteriovenous malformation. Of 13 cases with light blue or normal skin and subcutaneous mass, 7 cases involuted in varying degree; 6 cases grow gradually and didn't disappear, 2 cases were confirmed as venous malformation by biopsy. CONCLUSIONS: Hemangioma in infant begins to involute within two years old. Vascular malformation or hemangioma with deep vascular malformation grows persistently and does not disappear. Skin temperature of lesion surface and dilative veins on the skin artery pulsation, are indexes compressibility, for differentiation between hemangioma and vascular malformation in clinical diagnosis.

[Clinical analysis of 13 cases of hemangioma and vascular malformation associated with thrombopenia].

PURPOSE: To explore the diagnosis and treatment of hemangioma and vascular malformation associated with thrombopenia (Kasabach-Merritt syndrome, KMS). METHODS: From October 1997 to December 2003, 13 cases of KMS were treated in our hospital. Among the 13 patients, 4 were located in the maxillofacial region, 3 were located in the trunk, 6 were located in the lower limb. The size of the lesion of all patients exceeded 8 cm; 10 were hemangioma, 1 was arteriovenous malformation (AVM), 1 was venous malformation (VM), 1 was Klippel-Trenaunay Syndrome (KTS). The platelet count was all lower than 70 x 10(9)/L, the lowest was 10 x 10(9)/L, the average was 41 x 10(9)/L. The clinical characteristics and course of treatment were analyzed. RESULTS: 9 patients were cured, 1 improved, 1 had no response, and 2 died. The treatment of choice for KMS was steroids, but the response rate was not high (23.08% in this series). If patients had no response to steroids, they also had no response to interferon. CONCLUSIONS: If a proper treatment was taken in early stage, most patients could get a good result, but for patients with an extensive vascular malformation that can't be removed, the prognosis was poor. For lesions in the limbs and trunk, pneumatic compression therapy has certain curative effect, fewer side effects, therefore worthy of popularization.

[The clinical classification and treatment of arteriovenous malformations of maxilloface].

OBJECTIVE: To explore the clinical classification and ideal therapy for maxillofacial AVMs. METHODS: According to the clinical characteristics, 106 patients with maxillofacial AVMs were divided into the 4 types Of them, 38 cases were cystic dilatation lesions, 22 cases were limited thicken lesions, 42 case were diffuse thicken lesions, 4 cases were central maxillary hemangioma. 106 patients with maxillofacial AVMs were treated in our hospital, of them, 8 cases received operation (group 1); 23 cases received embolization of supplying artery alone (group 2); 37 cases received embolization of supplying artery plus hardener intra-tumorous injection (group 3); 38 cases received embolization of supplying artery plus tumor resection (group 4). RESULTS: Of all the patients were followed up 1 - 11 years, In group 1, 2, 3, and 4, the cure rates is 62.50%, 17.39%, 89.19%, and 97.37% respectively. one patient died of embolization of abnormal communication branches between external carotid and intra-cranical arteries. CONCLUSIONS: (1) This new clinical classification is beneficial for selecting method of treatment. (2) It is necessary that a good digital subtraction angiography for maxillofacial AVMs. (3) The embolization of tumor supplying artery alone could cure the small AVM with single branch terminal blood supply. (4) The embolization of supplying artery plus hardener intratumorous injection or the embolization of supplying artery plus tumor resection is an effective method for maxillofacial AVMs.

[Interventions for nasal hemangiomas in children].

OBJECTIVE: To explore an ideal therapy for nasal hemangiomas in children. METHODS: From June 1998 to April 2001, 110 patients with nasal hemangiomas in children were treated. Of them, 76 cases received Pingyangmycin intralesional injection (group I); 11 cases received steroids injection (group II); 7 cases received intralesional injection of absolute ethanol (group III); 6 cases received cryotherapy (group IV) and 10 cases with tumor resection (group V). RESULTS: In group I, II, III, IV and V, the cure rates were 88.16%, 27.27%, 100%, 50% and 80%, respectively. The satisfactory rates of the nasal contour after treatment were 86.84%, 18.18%, 0,0% and 10.00%, respectively. CONCLUSION: The nose is a special portion of the body with fine configuration. Once destroyed, it is difficult to restore. Therefore, it is necessary to adopt an effective therapy in the earlier stage. It is not advocated to wait for spontaneous involution. Intralesional injection of Pingyangmycin is an effective method in the treatment of nasal hemangiomas in children; Its result is exact, without significant side effects. The nasal appearance remains good after treatment.