USP18 enhances the resistance of BRAF-mutated melanoma cells to vemurafenib by stabilizing cGAS expression to induce cell autophagy.

This study aims to discern the possible molecular mechanism of the effect of ubiquitin-specific peptidase 18 (USP18) on the resistance to BRAF inhibitor vemurafenib in BRAF V600E mutant melanoma by regulating cyclic GMP-AMP synthase (cGAS). The cancer tissues of BRAF V600E mutant melanoma patients before and after vemurafenib treatment were collected, in which the protein expression of USP18 and cGAS was determined. A BRAF V600E mutant human melanoma cell line (A2058R) resistant to vemurafenib was constructed with its viability, apoptosis, and autophagy detected following overexpression and depletion assays of USP18 and cGAS. Xenografted tumors were transplanted into nude mice for in vivo validation. Bioinformatics analysis showed that the expression of cGAS was positively correlated with USP18 in melanoma, and USP18 was highly expressed in melanoma. The expression of cGAS and USP18 was up-regulated in cancer tissues of vemurafenib-resistant patients with BRAF V600E mutant melanoma. Knockdown of cGAS inhibited the resistance to vemurafenib in A2058R cells and the protective autophagy induced by vemurafenib in vitro. USP18 could deubiquitinate cGAS to promote its protein stability. In vivo experimentations confirmed that USP18 promoted vemurafenib-induced protective autophagy by stabilizing cGAS protein, which promoted resistance to vemurafenib in BRAF V600E mutant melanoma cells. Collectively, USP18 stabilizes cGAS protein expression through deubiquitination and induces autophagy of melanoma cells, thereby promoting the resistance to vemurafenib in BRAF V600E mutant melanoma.

GDC-0084 inhibits cutaneous squamous cell carcinoma cell growth.

GDC-0084 is a novel and potent small-molecule PI3K-mTOR dual inhibitor. The present study examined its potential activity in cutaneous squamous cell carcinoma (cSCC) cells. Our results show that GDC-0084 treatment at nanomole concentrations potently inhibited survival and proliferation of established (A431, SCC-13 and SCL-1 lines) and primary human cSCC cells. GDC-0084 induced apoptosis activation and cell cycle arrest in the cSCC cells. It was more efficient than other known PI3K-Akt-mTOR inhibitors in killing cSCC cells, but was non-cytotoxic to the normal human skin fibroblasts/keratinocytes. In A431 cells and primary cSCC cells, GDC-0084 blocked phosphorylation of key PI3K-Akt-mTOR components, including p85, Akt, S6K1 and S6. GDC-0084 also inhibited DNA-PKcs activation in cSCC cells. Significantly, restoring DNA-PKcs activation by a constitutively active-DNA-PKcs (S2056D) partially inhibited GDC-0084-induced cell death and apoptosis in A431 cells. In vivo, GDC-0084 daily gavage potently inhibited A431 xenograft tumor growth in mice. In GDC-0084-treated tumor tissues PI3K-Akt-mTOR and DNA-PKcs activation were significantly inhibited. In summary, GDC-0084 inhibits human cSCC cell growth in vitro and in vivo through blocking PI3K-Akt-mTOR and DNA-PKcs signalings.

[Effect of salvia miltiorrhiza and Ligustrazine injection on the early myocardial damage of patients with severe burn].

OBJECTIVE: To observe the effect of salvia miltiorrhiza and ligustrazine injection on the early myocardial damage of severely burned patients. METHODS: Twenty severely burned patients hospitalized from January 2010 to August 2011, with burn area equal to or more than 50% TBSA, were divided into two groups following hospitalization sequence, with odd number patients entering treatment group (T, n = 10) and even number patients entering control group (C, n = 10). Patients in C group were treated with routine methods, including fluid resuscitation based on the Third Military Medical University formula, anti-infection treatment, support treatment, and organ-protection treatment, etc. In addition to routine treatment methods, patients in T group received intravenous infusion of 250 mL glucose injection (50 g/L) containing 10 mL salvia miltiorrhiza and ligustrazine concoction, once a day, and continued for three days. Venous blood of patients was drawn at post burn hour (PBH) 12, 24, 48, and 72 to determine the plasma levels of cardiac troponin I (cTnI), creatine kinase isozyme MB (CK-MB), and atrial natriuretic peptide (ANP). Data were processed with t test. RESULTS: At each time point, levels of cTnI, CK-MB, and ANP were lower in T group than in C group. Differences in contents of these parameters between two groups were statistically significant at most time points, with t values from 2.136 to 2.918, P < 0.05 or P < 0.01. Plasma levels of cTnI, CK-MB, and ANP in both groups peaked at PBH 12, which were respectively (28 ± 10) ng/mL, (76 ± 13) U/L, (430 ± 87) pg/mL in T group, and (38 ± 11) ng/mL, (87 ± 10) U/L, (453 ± 91) pg/mL in C group. From PBH 24 to 72, contents of above-mentioned parameters decreased gradually in both groups. CONCLUSIONS: Early use of salvia miltiorrhiza and ligustrazine injection in severely burned patients can effectively reduce myocardial damage, thus protect the myocardium from injury.