Analysis of the nischarin expression across human tumor types reveals its context-dependent role and a potential as a target for drug repurposing in oncology

Nischarin was reported to be a tumor suppressor that plays a critical role in breast cancer initiation and progression, and a positive prognostic marker in breast, ovarian and lung cancers. Our group has found that nischarin had positive prognostic value in female melanoma patients, but negative in males. This opened up a question whether nischarin has tumor type-specific and sex-dependent roles in cancer progression. In this study, we systematically examined in the public databases the prognostic value of nischarin in solid tumors, regulation of its expression and associated signaling pathways. We also tested the effects of a nischarin agonist rilmenidine on cancer cell viability in vitro. Nischarin expression was decreased in tumors compared to the respective healthy tissues, most commonly due to the deletions of the nischarin gene and promoter methylation. Unlike in healthy tissues where it was located in the cytoplasm and at the membrane, in tumor tissues nischarin could also be observed in the nuclei, implying that nuclear translocation may also account for its cancer-specific role. Surprisingly, in several cancer types high nischarin expression was a negative prognostic marker. Gene set enrichment analysis showed that in tumors in which high nischarin expression was a negative prognostic marker, signaling pathways that regulate stemness were enriched. In concordance with the findings that nischarin expression was negatively associated with pathways that control cancer growth and progression, nischarin agonist rilmenidine decreased the viability of cancer cells in vitro. Taken together, our study lays a ground for functional studies of nischarin in a context-dependent manner and, given that nischarin has several clinically approved agonists, provides rationale for their repurposing, at least in tumors in which nischarin is predicted to be a positive prognostic marker.

Abstract 2476: Nischarin is a potential druggable target in both epithelial and stromal compartments of pancreatic ductal adenocarcinoma

Nischarin is a scaffolding protein involved in the regulation of cell cytoskeletal organization and metabolic homeostasis. In breast and ovarian cancers, nischarin has been demonstrated to have tumor suppressive functions. We have found that nischarin was expressed in both the epithelial and stromal compartments of the PDAC patient tissue, in cancer cell lines and patient-derived stellate cells. Of interest, nischarin is a functional imidazoline 1 receptor for which there are several FDA-approved agonists used for treatment of hypertension. The aim of this study was to examine the effects of nischarin agonists on PDAC cancer cells and stellate cells, separately and in co-culture and determine the potential for their repurposing in treatment of PDAC. mRNA sequencing revealed that cancer cell treatment with nischarin agonist rilmenidine induced transcriptional changes associated with regulation of cell adhesion, EMT and vesicular transport. In vitro, rilmenidine treatment of cancer cells decreased their migration and invasion potential and treatment of stellate cells decreased the αSMA-positive fraction. Treatment of cancer cell-stellate cell co-cultures decreased the production of pro-inflammatory cytokines IL-6, IL-8 and CCL-2, known drivers of the metastatic progression. Ultimately, rilmenidine treatment decreased PDAC cell invasion in Tg(fli1: EGFP) zebrafish model. Taken together, nischarin agonist rilmenidine has a potential for limiting the processes involved in PDAC metastatic cascade and may be a good candidate for drug repurposing.

Citation Format: Jelena Grahovac, Kristina Živić, Marijana Pavlović, Marija Ostojić, Ana Đurić, Tatjana Srdić-Rajić, Aleksandar Pavić, Danijel Galun. Nischarin is a potential druggable target in both epithelial and stromal compartments of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2476.

Chemical Characterization and Bioactive Properties of the Edible and Medicinal Honey Mushroom Armillaria Mellea (Agaricomycetes) from Serbia

Honey mushroom, Armillaria mellea, is an edible and medicinal lignicolous basidiomycete. In this study, we investigated the chemical composition and bioactive properties of its methanolic and acetonic extracts. The chemical characterization of extracts was done with the HPLC-DAD-MS/MS method. The results showed that potassium was the most abundant mineral; chlorogenic acid was the most abundant polyphenol; malic acid was the most abundant organic acid; and among carbohydrates, the most abundant were sorbitol, glucose, fructose, and saccharose. Antioxidative activity was assessed by DPPH (IC50 of the methanolic extract was 608.32 μg/mL and of the acetonic extract 595.71 μg/mL) and reducing power assays (the results ranged between 0.034 and 0.102 μg/mL). Total phenolic content was determined as gallic acid equivalent (methanolic extract: 4.74 mg GAE/g; acetonic extract: 5.68 mg GAE/g). The microdilution assay was used to evaluate the antimicrobial activity of the extracts, and the results ranged from 1.25 to 20 mg/mL. The antidiabetic effect of the extracts was tested by the α-amylase (the results ranged from 34.90% to 41.98%) and α-glucosidase assays (the results were in the range of 0.55-2.79%). The neuroprotective activity was explored by the acetylcholinesterase inhibition assay (the results were in the range of 1.94-7.76%). The microtetrazolium assay was used to investigate the cytotoxic activity of the extracts (the IC50 values ranged from 212.06 to > 400 μg/mL). Although some results suggest that some activities of the extracts are relatively moderate, the honey mushroom can still be considered an excellent source of food and bioactive compounds with medicinal value.

Bioactivity and phenolics profile of aqueous and ethyl acetate extracts of Satureja kitaibelii Wierzb. ex Heuff. obtained by ultrasound-assisted extraction

The aim of the study was to investigate the biological activity and chemical composition of Satureja kitaibelii Wierzb. ex Heuff. LC-PDA/MS analyses for the aqueous extracts (A1-stem, leaves and flowers, A2-leaves and flowers) and ethyl-acetate extracts (E1-stem, leaves and flowers, E2-leaves and flowers) obtained by ultrasound-assisted extraction enabled the identification of thirty-four compounds. Quantitative analysis revealed that the aqueous extract obtained from leaves and flowers was the richest in total phenolic acids (65.36 mg/g) and flavonoids (21.17 mg/g). The total polyphenol content was the highest in the aqueous extract obtained from leaves and flowers (274 ± 2.4 mg Gallic Acid equivalents/g). The best antioxidant activity was observed for the same extract using the DPPH (SC50 20 ± 10 µg/mL), ABTS (2.834 ± 0.02 mg Ascorbic Acid/g), FRAP (1.922 ± 0.03 mmol Fe²⁺/mg), and total reducing power tests (16.4 ± 1.0 mg Ascorbic Acid/g). Both ethyl acetate extracts were the most active against strains of Bacillus cereus and Micrococcus flavus (MIC 1.70-1.99 mg/mL and 1.99-3.41 mg/mL, respectively). They were more efficient against Aspergillus ochraceus (MFC 0.86 mg/mL) and towards HeLa cell lines. All the obtained results implied the good potential of the investigated extracts to be used as effective preservatives and functional ingredients in food products and dietary supplements.