Effects of losartan and l-serine in a mouse liver fibrosis model

Hepatic fibrosis is a common liver disease caused by excessive collagen deposition in the liver. Since liver transplantation is the only current treatment for cirrhosis with worsened fibrosis, a new strategy to develop anti-fibrosis drugs with no adverse effects is necessary. In recent studies, amino acids have been applied as a type of therapy in various fields. l-serine plays a major role in antioxidant production via the maintenance of nicotinamide adenine dinucleotide phosphate hydride production in the mitochondria. l-serine may reduce fibrotic lesions in a mouse model of chronic liver injury. This study used 27 six-week-old C57BL/6 mice and injected them three times a week for eight weeks with carbon tetrachloride (CCl₄) (1.5 mg/kg, 10% v/v CCl₄ in olive oil) to create a hepatic fibrosis mouse model. The mice, which weighed approximately 20-30 g, were randomly classified into four groups: 1) the olive oil group, which received intraperitoneal injection of olive oil (1.5 mg/kg, 3 times per week for 8 weeks); 2) the CCl4-only group; 3) the CCl4 + losartan (10 mg/kg, PO, 5 days on, weekend off for 8 weeks) group; and 4) the CCl4 + l-serine (100 g/L, free access for 8 weeks) group. Hematoxylin and eosin staining and Masson's trichrome staining showed reduced inflammatory cell deposition and collagen deposition in the liver tissue in the l-serine supplemented group. l-serine was found to reduce the spread of hepatic fibrosis and has potential use in clinical settings. Based on these histopathological observations, l-serine is a potential anti-fibrosis drug.

Molecular profiling of Asian patients with advanced melanoma receiving check-point inhibitor treatment

Objective

Melanoma is major medical challenge and being able to monitor treatment response is critical. This study aimed to use molecular profiling of Asian patients with advanced melanoma who were receiving treatment with check-point inhibitors (CPIs) to identify novel biomarkers of tumor response.

Methods

Next-generation sequencing (NGS) was performed using tumor specimens collected from 178 Asian patients with metastatic melanoma receiving CPIs. The NGS data and clinical-pathological factors were analyzed for potential genetic biomarkers of tumor response to CPI treatment.

Results

The most common melanoma subtype was acral melanoma (40%), followed by cutaneous melanoma (32%), mucosal melanoma (26%), and others (2%). For calculation of treatment efficacy, 164 of the patients could be evaluated. The overall response rate was 45.7%, of which 41 cases exhibited complete responses (25.0%) and 34 showed partial responses (20.7%). There were no significant differences in tumor responses based on melanoma subtype (P = 0.295). Genetically, NRAS mutations, TP53 mutations, and NF2 deletions were significantly associated with resistance to CPIs (P < 0.05). In contrast, MYC and RPS6KB1 amplifications were associated with responsiveness to CPIs (P < 0.05). Median progression-free survival (PFS) for patients treated with CPIs was 5.9 months (95% CI, 3.8-8.05 months). Univariate analysis identified TP53 and BRAF mutations, NF2 deletions, and BIRC2 amplifications as poor prognostic factors for PFS (P < 0.05).

Conclusions

This study determined the integrated genomic profiles of Asian patients with metastatic melanoma receiving CPIs and identified candidate biomarkers that reflected treatment outcomes.

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The molecular characterization of Asian melanoma patients receiving check-point inhibitors (CPIs) using NGS has not been reported.

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NRAS and TP53 mutations and NF2 deletions were significantly associated with resistance to CPIs.

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MYC and RPS6KB1 amplifications were associated with responsiveness to CPIs.

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TP53 and BRAF mutations, NF2 deletions, and BIRC2 amplifications were poor prognostic factors for progression-free survival.

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This is the largest integrated genomic study to date that identifying novel biomarkers of CPIs in Asian melanoma patients.

Evaluation of class I HDAC isoform selectivity of largazole analogues

Largazole is a potent class I selective histone deacetylase (HDAC) inhibitor. The majority of largazole analogues to date have modified the thiazole-thiazoline and the warhead moiety. In order to elucidate class I-specific structure-activity relationships, a series of analogues with modifications in the valine or the linker region were prepared and evaluated for their class I isoform selectivity. The inhibition profile showed that the C2 position of largazole has an optimal steric requirement for efficient HDAC inhibition and that substitution of the trans-alkene in the linker with an aromatic group results in complete loss of activity. This data will aid the design of class I isoform selective HDAC inhibitors.

Anticolon cancer activity of largazole, a marine-derived tunable histone deacetylase inhibitor

Histone deacetylases (HDACs) are validated targets for anticancer therapy as attested by the approval of suberoylanilide hydroxamic acid (SAHA) and romidepsin (FK228) for treating cutaneous T cell lymphoma. We recently described the bioassay-guided isolation, structure determination, synthesis, and target identification of largazole, a marine-derived antiproliferative natural product that is a prodrug that releases a potent HDAC inhibitor, largazole thiol. Here, we characterize the anticancer activity of largazole by using in vitro and in vivo cancer models. Screening against the National Cancer Institute's 60 cell lines revealed that largazole is particularly active against several colon cancer cell types. Consequently, we tested largazole, along with several synthetic analogs, for HDAC inhibition in human HCT116 colon cancer cells. Enzyme inhibition strongly correlated with the growth inhibitory effects, and differential activity of largazole analogs was rationalized by molecular docking to an HDAC1 homology model. Comparative genomewide transcript profiling revealed a close overlap of genes that are regulated by largazole, FK228, and SAHA. Several of these genes can be related to largazole's ability to induce cell cycle arrest and apoptosis. Stability studies suggested reasonable bioavailability of the active species, largazole thiol. We established that largazole inhibits HDACs in tumor tissue in vivo by using a human HCT116 xenograft mouse model. Largazole strongly stimulated histone hyperacetylation in the tumor, showed efficacy in inhibiting tumor growth, and induced apoptosis in the tumor. This effect probably is mediated by the modulation of levels of cell cycle regulators, antagonism of the AKT pathway through insulin receptor substrate 1 down-regulation, and reduction of epidermal growth factor receptor levels.