Short-term starvation synergistically enhances cytotoxicity of Niraparib via Akt/mTOR signaling pathway in ovarian cancer therapy

NEK6 dampens FOXO3 nuclear translocation to stabilize C-MYC and promotes subsequent de novo purine synthesis to support ovarian cancer chemoresistance

De novo purine synthesis metabolism plays a crucial role in tumor cell survival and malignant progression. However, the specific impact of this metabolic pathway on chemoresistance in ovarian cancer remains unclear. This study aims to elucidate the influence of de novo purine synthesis on chemoresistance in ovarian cancer and its underlying regulatory mechanisms. We analyzed metabolic differences between chemosensitive and chemoresistant ovarian cancer tissues using mass spectrometry-based metabolomics. Cell growth, metabolism, chemoresistance, and DNA damage repair characteristics were assessed in vitro using cell line models. Tumor growth and chemoresistance were assessed in vivo using ovarian cancer xenograft tumors. Intervention of purines and NEK6-mediated purine metabolism on chemoresistance was investigated at multiple levels. Chemoresistant ovarian cancers exhibited higher purine abundance and NEK6 expression. Inhibiting NEK6 led to decreased de novo purine synthesis, resulting in diminished chemoresistance in ovarian cancer cells. Mechanistically, NEK6 directly interacted with FOXO3, contributing to the phosphorylation of FOXO3 at S7 through its kinase activity, thereby inhibiting its nuclear translocation. Nuclear FOXO3 promoted FBXW7 transcription, leading to c-MYC ubiquitination and suppression of de novo purine synthesis. Paeonol, by inhibiting NEK6, suppressed de novo purine synthesis and enhanced chemosensitivity. The NEK6-mediated reprogramming of de novo purine synthesis emerges as a critical pathway influencing chemoresistance in ovarian cancer. Paeonol exhibits the potential to interfere with NEK6, thereby inhibiting chemoresistance.

Advancements and Obstacles of PARP Inhibitors in Gastric Cancer

Gastric cancer (GC) is a common and aggressive cancer of the digestive system, exhibiting high aggressiveness and significant heterogeneity. Despite advancements in improving survival rates over the past few decades, GC continues to carry a worrisome prognosis and notable mortality. As a result, there is an urgent need for novel therapeutic approaches to address GC. Recent targeted sequencing studies have revealed frequent mutations in DNA damage repair (DDR) pathway genes in many GC patients. These mutations lead to an increased reliance on poly (adenosine diphosphate-ribose) polymerase (PARP) for DNA repair, making PARP inhibitors (PARPi) a promising treatment option for GC. This article presents a comprehensive overview of the rationale and development of PARPi, highlighting its progress and challenges in both preclinical and clinical research for treating GC.

Human PARP1 substrates and regulators of its catalytic activity: An updated overview

Poly (ADP-ribose) polymerase 1 (PARP1) is a key DNA damage sensor that is recruited to damaged sites after DNA strand breaks to initiate DNA repair. This is achieved by catalyzing attachment of ADP-ribose moieties, which are donated from NAD⁺, on the amino acid residues of itself or other acceptor proteins. PARP inhibitors (PARPi) that inhibit PARP catalytic activity and induce PARP trapping are commonly used for treating BRCA1/2-deficient breast and ovarian cancers through synergistic lethality. Unfortunately, resistance to PARPi frequently occurs. In this review, we present the novel substrates and regulators of the PARP1-catalyzed poly (ADP-ribosyl)ation (PARylatison) that have been identified in the last 3 years. The overall aim is the presentation of protein interactions of potential therapeutic intervention for overcoming the resistance to PARPi.