Targeting nicotinamide N-methyltransferase decreased aggressiveness of osteosarcoma cells

Nicotinamide N-Methyltransferase (NNMT) and Liver Cancer: From Metabolic Networks to Therapeutic Targets

Hepatocellular carcinoma (HCC), the predominant form of primary liver cancer, remains a global health challenge with limited therapeutic options and high mortality rates. Despite advances in understanding its molecular pathogenesis, the role of metabolic reprogramming in HCC progression and therapy resistance demands further exploration. Nicotinamide N-methyltransferase (NNMT), a metabolic enzyme central to NAD+ and methionine cycles, has emerged as a critical regulator of tumorigenesis across cancers. However, its tissue-specific mechanisms in HCC-particularly in the context of viral hepatitis and methionine cycle dependency-remain understudied. This review systematically synthesizes current evidence on NNMT's dual role in HCC: (1) driving NAD+ depletion and homocysteine (Hcy) accumulation via metabolic dysregulation, (2) promoting malignant phenotypes (proliferation, invasion, metastasis, and drug resistance), and (3) serving as a prognostic biomarker and therapeutic target. We highlight how NNMT intersects with epigenetic modifications, immune evasion, and metabolic vulnerabilities unique to HCC. Additionally, we critically evaluate NNMT inhibitors, RNA-based therapies, and non-pharmacological strategies (e.g., exercise) as novel interventions. By bridging gaps between NNMT's molecular mechanisms and clinical relevance, this review provides a roadmap for advancing NNMT-targeted therapies and underscores the urgency of addressing challenges in biomarker validation, inhibitor specificity, and translational efficacy. Our work positions NNMT not only as a metabolic linchpin in HCC but also as a promising candidate for precision oncology.

Synergistic HDAC4/8 Inhibition Sensitizes Osteosarcoma to Doxorubicin via pAKT/RUNX2 Pathway Modulation

Osteosarcoma is a highly aggressive bone malignancy, particularly challenging in metastatic cases, with a 5-year survival rate remaining under 30%. Although doxorubicin (doxo) is a standard first-line chemotherapeutic agent, its clinical utility is often hindered by the development of drug resistance and associated systemic toxicity. Emerging evidence highlights the role of epigenetic alterations, particularly those involving histone deacetylases (HDACs), in promoting chemoresistance. In this context, the present study aimed to evaluate the therapeutic potential of combining doxo with the selective HDAC inhibitors, tasquinimod (Tas, targeting HDAC4) and PCI-34051 (PCI, targeting HDAC8), in SJSA-1 osteosarcoma cells. Utilizing both 2D and 3D in vitro models, the combination treatment (referred to as the T4 group) significantly reduced cell viability by 57.69% in 2D cultures and decreased spheroid volume by 35.19% in 3D models. The apoptotic response was markedly enhanced, with late apoptosis reaching 64.59% and necrosis at 32.07%, both surpassing the effects observed with doxo alone. Furthermore, wound healing assays demonstrated a 37.74% inhibition of migration, accompanied by a decreased expression of the matrix metalloproteinases MMP9 and MMP13. Mechanistically, the combination therapy led to the downregulation of protein kinase B (pAKT) and RUNX2, along with upregulation of apoptotic markers, including caspase 8, caspase 3, and cleaved caspase 3, indicating a disruption of key survival pathways. These findings suggest that dual HDAC inhibition with Tas and PCI can potentiate doxo efficacy by enhancing apoptosis, inhibiting proliferation, and reducing metastatic potential, thus offering a promising strategy to overcome chemoresistance in osteosarcoma. Further preclinical and clinical studies are required to validate these therapeutic benefits.

Exploring NNMT: from metabolic pathways to therapeutic targets

Cellular metabolism-related epigenetic modulation plays a pivotal role in the maintenance of cellular homeostasis. Nicotinamide N-methyltransferase (NNMT) serves as a crucial link between cellular metabolism and epigenetics by catalyzing nicotinamide methylation using the universal methyl donor S-adenosyl-L-methionine. This direct connection bridges the methylation-mediated one-carbon metabolism with nicotinamide adenine dinucleotide levels. Numerous studies have revealed tissue-specific differences in NNMT expression and activity, indicating that its varied physiological and pathological roles depend on its distribution. In this review, we provide an overview of the NNMT involvement in various pathological conditions, including cancer, liver disease, obesity, diabetes, brain disease, pulmonary disease, cardiovascular disease, and kidney disease. By synthesizing this information, our article aims to enhance our understanding of the cellular mechanisms underlying NNMT biology related to diverse diseases and lay the molecular groundwork for developing therapeutic strategies for pharmacological interventions.

Special Issue "Ovarian Cancer: Advances on Pathophysiology and Therapies"

Ovarian cancer is a gynecologic cancer with a high mortality rate, and its incidence has increased significantly over the past 50 years [...].

In Vitro Study of the Proliferation of MG63 Cells Cultured on Five Different Titanium Surfaces

The use of dental implants for prosthetic rehabilitation in dentistry is based on the concept of osteointegration. This concept enables the clinical stability of the implants and a total absence of inflammatory tissue between the implant surface and the bone tissue. For this reason, it is essential to understand the role of the titanium surface in promoting and maintaining or not maintaining contact between the bone matrix and the surface of the titanium implant.

MATERIALS AND METHODS

Five types of titanium discs placed in contact with osteoblast cultures of osteosarcomas were studied. The materials had different roughness. Scanning electron microscopy (SEM) photos were taken before the in vitro culture to analyze the surfaces, and at the end of the culturing time, the different gene expressions of a broad pattern of proteins were evaluated to analyze the osteoblast response, as indicated in the scientific literature.

RESULTS

It was demonstrated that the responses of the osteoblasts were different in the five cultures in contact with the five titanium discs with different surfaces; in particular, the response in the production of some proteins was statistically significant.

DISCUSSION

The key role of titanium surfaces underlines how it is still possible to carry out increasingly accurate and targeted studies in the search for new surfaces capable of stimulating a better osteoblastic response and the long-term maintenance of osteointegration.