The AKT inhibitor AZD5363 elicits synthetic lethality in ARID1A-deficient gastric cancer cells via induction of pyroptosis.

BACKGROUND: Gastric cancer (GC) is a deadly disease with poor overall survival and limited therapeutic options. Genetic alterations such as mutations and/or deletions in chromatin remodeling gene AT-rich interactive domain 1 A (ARID1A) occur frequently in GC. Although ARID1A mutations/deletions are not a druggable target for conventional treatments, novel therapeutic strategies based on a synthetic lethal approach may be effective for the treatment of ARID1A-deficient cancers. METHODS: A kinase inhibitor library containing 551 compounds was screened in ARID1A isogenic GC cells for the ability to induce synthetic lethality effect. Selected hits' activity was validated, and the mechanism of the most potent candidate drug, AKT inhibitor AD5363 (capivasertib), on induction of the synthetic lethality with ARID1A deficiency was investigated. RESULTS: After robust vulnerability screening of 551 diverse protein kinase inhibitors, we identified the AKT inhibitor AZD5363 as being the most potent lead compound in inhibiting viability of ARID1A-/- cells. A synthetic lethality between loss of ARID1A expression and AKT inhibition by AZD5363 was validated in both GC cell model system and xenograft model. Mechanistically, AZD5363 treatment induced pyroptotic cell death in ARID1A-deficient GC cells through activation of the Caspase-3/GSDME pathway. Furthermore, ARID1A occupied the AKT gene promoter and regulated its transcription negatively, thus the GC cells deficient in ARID1A showed increased expression and phosphorylation of AKT. CONCLUSIONS: Our study demonstrates a novel synthetic lethality interaction and unique mechanism between ARID1A loss and AKT inhibition, which may provide a therapeutic and mechanistic rationale for targeted therapy on patients with ARID1A-defective GC who are most likely to be beneficial to AZD5363 treatment.

OTUD1 enhances gastric cancer aggressiveness by deubiquitinating EBV-encoded protein BALF1 to stabilize the apoptosis inhibitor Bcl-2.

The Epstein-Barr virus (EBV) is implicated in several cancers, including EBV-associated gastric cancer (EBVaGC). This study focuses on EBV-encoded BALF1 (BamH1 A fragment leftward reading frame 1), a key apoptosis regulator in EBV-related cancers, whose specific impact on EBVaGC was previously unknown. Our findings indicate that BALF1 overexpression in gastric cancer cells significantly enhances their proliferation, migration, and resistance to chemotherapy-induced apoptosis, confirming BALF1's oncogenic potential. A novel discovery is that BALF1 undergoes degradation via the ubiquitin-proteasome pathway. Through analysis of 69 deubiquitinating enzymes (DUBs), ovarian tumor protease (OTU) domain-containing protein 1 (OTUD1) emerged as a vital regulator for maintaining BALF1 protein stability. Furthermore, BALF1 was found to play a role in regulating the stability of the B-cell lymphoma-2 (Bcl-2) protein, increasing its levels through deubiquitination. This mechanism reveals BALF1's multifaceted oncogenic role in gastric cancer, as it contributes both directly and indirectly to cancer progression, particularly by stabilizing Bcl-2, known for its anti-apoptotic characteristics. These insights significantly deepen our understanding of EBV's involvement in the pathogenesis of gastric cancer. The elucidation of OTUD1's role in BALF1 regulation and its influence on Bcl-2 stabilization provide new avenues for therapeutic intervention in EBVaGC, bridging the gap between viral oncogenesis and cellular protein regulation and offering a more holistic view of gastric cancer development under the influence of EBV.

Stereoselective Synthesis of Xylodonin A and 22-Hydroxyxylodonin A and Discovery of Analogues with Cytotoxic Activity.

The first and stereoselective synthesis of xylodonin A and 22-hydroxyxylodonin A, two drimane-type sesquiterpenoid natural products, was developed from the readily available (+)-sclareolide. This route features an allylic oxidation and acid-promoted dehydration for construction of the key intermediate 6-hydroxyisodrimenin. Representative analogues were synthesized, and their previously unknown bioactivities were revealed after biological evaluation. The analogue 19a exhibited cytotoxic activity against liver cancer HepG2 cells (IC50: 8.8 vs 5.9 µM) that was comparable to that of the clinical anticancer drug etoposide with lower toxicity to normal liver HL7702 cells (IC50 > 100 µM).

Divergent and Stereoselective Synthesis of Ustusal A, (-)-Albrassitriol, and Elegansin D.

The first synthesis of ustusal A as well as expeditious access to (-)-albrassitriol is described as featuring a singlet oxygen [4 + 2] cycloaddition, achieving the desired stereoselectivity for the 1,4-cis-hydroxyl groups. Transformation of (+)-sclareolide to III followed by a key Horner-Wadsworth-Emmons (HWE) reaction and stereospecific allylic oxidation facilitated the first synthesis of elegansin D. The biological evaluation of these natural products together with seven elegansin D analogues was performed, among which several elegansin D analogues exhibited potential anticancer activity against liver cancer HepG2 cells (IC50 = 11.99-25.58 µM) with low cytotoxicity on normal liver HL7702 cells (IC50 > 100 µM).

Novel Refreshable Braille Display Based on the Layered Electromagnetic Driving Mechanism of Braille Dots.

In the digital era, Braille displays enable visually impaired people to easily access information. Different from traditional piezoelectric Braille displays, a novel electromagnetic Braille display is realized in this study. The novel display has the advantages of a stable performance, a long service life and a low cost and is based on an innovative layered electromagnetic driving mechanism of Braille dots, which can achieve a dense arrangement of Braille dots and provide a sufficient support force for them. The T-shaped screw compression spring, which causes the Braille dots to fall back instantaneously, is optimized to achieve a high refresh frequency and to enable visually impaired people to read Braille quickly. The experimental results show that under an input voltage of 6 V, the Braille display can work stably and reliably and provide a good fingertip touch; the Braille dot support force is greater than 150 mN, the maximum refresh frequency can reach 50 Hz, and the operating temperature is lower than 32 °C. Therefore, this cost-effective Braille display is expected to benefit a vast number of low-income visually impaired people in developing countries and improve their learning, working and living conditions.

Transcriptional Regulation of Siglec-15 by ETS-1 and ETS-2 in Hepatocellular Carcinoma Cells.

Sialic acid-binding immunoglobulin-like lectin 15 (Siglec-15) has been identified as a crucial immune suppressor in human cancers, comparable to programmed cell death 1 ligand (PD-L1). However, the regulatory mechanisms underlying its transcriptional upregulation in human cancers remain largely unknown. Here, we show that the transcription factors ETS-1 and ETS-2 bound to the Siglec-15 promoter to enhance transcription and expression of Siglec-15 in hepatocellular carcinoma (HCC) cells and that transforming growth factor ß-1 (TGF-ß1) upregulated the expression of ETS-1 and ETS-2 and facilitated the binding of ETS-1 and ETS-2 to the Siglec-15 promoter. We further demonstrate that TGF-ß1 activated the Ras/C-Raf/MEK/ERK1/2 signaling pathway, leading to phosphorylation of ETS-1 and ETS-2, which consequently upregulates the transcription and expression of Siglec-15. Our study defines a detailed molecular profile of how Siglec-15 is transcriptionally regulated which may offer significant opportunity for therapeutic intervention on HCC immunotherapy.

Divergent Synthesis of Skeletally Distinct Arboridinine and Arborisidine.

A divergent synthesis of skeletally distinct arboridinine and arborisidine was achieved. The central divergent strategy was inspired by the divergent biosynthetic cyclization mode of arboridinine and arborisidine and their hidden topological connection. The branch point was reached through a Michael and Mannich cascade process. A site-selective intramolecular Mannich reaction was developed to construct the tetracyclic core of arboridinine, while a site-selective intramolecular α-amination of ketone was used to access the tetracyclic core of arborisidine. A strategic Peterson olefination through intramolecular nucleophile delivery was able to set up the exocyclic olefin of arboridinine.