Fatty acid synthase mediates high glucose-induced EGFR activation in oral dysplastic keratinocytes

A review on diabetes and oral cancer: Molecular links and implications

Diabetes mellitus has been linked to an increased risk of oral cancer, with hyperglycemia and chronic inflammation contributing to malignant transformation. Accumulating evidence has highlighted the role of specific genes and biomarkers associated with the process. While hyperglycemia accelerates cancer progression, Metformin, an anti-diabetic medication, is found to reduce the recurrence. Future research should focus on understanding molecular mechanisms, developing early diagnostic tools, and assessing the impact of glycemic control in managing potentially oral malignant lesions in diabetic patients.

Aberrant Energy Metabolism in Tumors and Potential Therapeutic Targets

Energy metabolic reprogramming is frequently observed during tumor progression as tumor cells necessitate adequate energy production for rapid proliferation. Although current medical research shows promising prospects in studying the characteristics of tumor energy metabolism and developing anti-tumor drugs targeting energy metabolism, there is a lack of systematic compendiums and comprehensive reviews in this field. The objective of this study is to conduct a systematic review on the characteristics of tumor cells' energy metabolism, with a specific focus on comparing abnormalities between tumor and normal cells, as well as summarizing potential targets for tumor therapy. Additionally, this review also elucidates the aberrant mechanisms underlying four major energy metabolic pathways (glucose, lipid, glutamine, and mitochondria-dependent) during carcinogenesis and tumor progression. Through the utilization of graphical representations, we have identified anomalies in crucial energy metabolism pathways, encompassing transporter proteins (glucose transporter, CD36, and ASCT2), signaling molecules (Ras, AMPK, and PTEN), as well as transcription factors (Myc, HIF-1α, CREB-1, and p53). The key molecules responsible for aberrant energy metabolism in tumors may serve as potential targets for cancer therapy. Therefore, this review provides an overview of the distinct energy-generating pathways within tumor cells, laying the groundwork for developing innovative strategies for precise cancer treatment.

Inhibitory Effects of the Polyphenols from the Root of Rhizophora apiculata Blume on Fatty Acid Synthase Activity and Human Colon Cancer Cells

Marine mangrove vegetation has been traditionally employed in folk medicine to address various ailments. Notably, Rhizophora apiculata Blume has exhibited noteworthy properties, demonstrating efficacy against cancer, viruses, and bacteria. The enzyme fatty acid synthase (FAS) plays a pivotal role in de novo fatty acid synthesis, making it a promising target for combating colon cancer. Our study focused on evaluating the FAS inhibitory effects of both the crude extract and three isolated compounds from R. apiculata. The n-butanol fraction of R. apiculata extract (BFR) demonstrated a significant inhibition of FAS, with an IC50 value of 93.0 µg/mL. For inhibition via lyoniresinol-3α-O-β-rhamnopyranoside (LR), the corresponding IC50 value was 20.1 µg/mL (35.5 µM). LR competitively inhibited the FAS reaction with acetyl-CoA, noncompetitively with malonyl-CoA, and in a mixed manner with NADPH. Our results also suggest that both BFR and LR reversibly bind to the KR domain of FAS, hindering the reduction of saturated acyl groups in fatty acid synthesis. Furthermore, BFR and LR displayed time-dependent inhibition for FAS, with kobs values of 0.0045 min-1 and 0.026 min-1, respectively. LR also exhibited time-dependent inhibition on the KR domain, with a kobs value of 0.019 min-1. In human colon cancer cells, LR demonstrated the ability to reduce viability and inhibit intracellular FAS activity. Notably, the effects of LR on human colon cancer cells could be reversed with the end product of FAS-catalyzed chemical reactions, affirming the specificity of LR on FAS. These findings underscore the potential of BFR and LR as potent FAS inhibitors, presenting novel avenues for the treatment of human colon cancer.

Glucose upregulates amphiregulin in oral dysplastic keratinocytes: A potential role in diabetes-associated oral carcinogenesis

BACKGROUND

Compelling evidence implicates diabetes-associated hyperglycemia as a promoter of tumor progression in oral potentially malignant disorders (OPMD). Yet, information on hyperglycemia-induced cell signaling networks in oral oncology remains limited. Our group recently reported that glucose-rich conditions significantly enhance oral dysplastic keratinocyte viability and migration through epidermal growth factor receptor (EGFR) activation, a pathway strongly linked to oral carcinogenesis. Here, we investigated the basal metabolic phenotype in these cells and whether specific glucose-responsive EGFR ligands mediate these responses.

METHODS

Cell energy phenotype and lactate concentration were evaluated via commercially available assays. EGFR ligands in response to normal (5 mM) or high (20 mM) glucose were analyzed by quantitative real-time PCR, ELISA, and western blotting. Cell viability and migration assays were performed in the presence of pharmacological inhibitors or RNA interference.

RESULTS

When compared to normal keratinocytes, basal glycolysis in oral dysplastic keratinocytes was significantly elevated. In highly glycolytic cells, high glucose-activated EGFR increasing viability and migration. Notably, we identified amphiregulin (AREG) as the predominant glucose-induced EGFR ligand. Indeed, enhanced cell migration in response to high glucose was blunted by EGFR inhibitor cetuximab and AREG siRNA. Conversely, AREG treatment under normal glucose conditions significantly increased cell viability, migration, lactate levels, and expression of glycolytic marker pyruvate kinase M2.

CONCLUSION

These novel findings point to AREG as a potential high glucose-induced EGFR activating ligand in highly glycolytic oral dysplastic keratinocytes. Future studies are warranted to gain more insight into the role of AREG in hyperglycemia-associated OPMD tumor progression.

Novel dental resin infiltrant containing smart monomer dodecylmethylaminoethyl methacrylate

Objectives

White spot lesions (WSLs) are prevalent and often lead to aesthetic problems and progressive caries. The objectives of this study were to: (1) develop a novel resin infiltrant containing smart monomer dodecylmethylaminoethyl methacrylate (DMAEM) to inhibit WSLs, and (2) investigate the effects of DMAEM incorporation on cytotoxicity, mechanical properties, biofilm-inhibition and protection of enamel hardness for the first time.

Methods

DMAEM was synthesized using 1-bromododecane, 2-methylamino ethanol and methylmethacrylate. DMAEM with mass fractions of 0%, 1.25%, 2.5% and 5% were incorporated into a resin infiltant containing BisGMA and TEGDMA. Cytotoxicity, mechanical properties and antibacterial effects were tested. After resin infiltration, bovine enamel was demineralized with saliva biofilm acids, and enamel hardness was measured.

Result

DMAEM infiltration did not increase the cytotoxicity or compromise the physical properties when DMAEM mass fraction was below 5% (p > 0.05). Biofilm metabolic activity was reduced by 90%, and biofilm lactic acid production was reduced by 92%, via DMAEM (p < 0.05). Mutans streptococci biofilm CFU was reduced by 3 logs (p < 0.05). When demineralized in acid and then under biofilms, the infiltrant + 5% DMAEM group produced an enamel hardness (mean ± sd; n = 6) of 2.90 ± 0.06 GPa, much higher than 0.85 ± 0.12 GPa of the infiltrant + 0% DMAEM group (p < 0.05).

Significance

A novel resin infiltrant with excellent mechanical properties, biocompability, strong antibacterial activity and anti-demineralization effect was developed using DMAEM for the first time. The DMAEM resin infiltrant is promising for inhibiting WSLs, arresting early caries, and protecting enamel hardness.

Metformin Downregulates the Expression of Epidermal Growth Factor Receptor Independent of Lowering Blood Glucose in Oral Squamous Cell Carcinoma

PURPOSE

Type 2 diabetes mellitus (T2DM) is among the risk factors for the occurrence and development of cancer. Metformin is a potential anticancer drug. Epidermal growth factor receptor (EGFR) plays an important role in the progression of oral squamous cell carcinoma(OSCC), but the relationship between metformin and EGFR expression in OSCC remains unclear.

METHODS

This study involved the immunohistochemical detection of EGFR expression in cancer tissues of patients with T2DM and OSCC. The patients were divided into groups according to whether they were taking metformin for the treatment of T2DM, and the expression of EGFR in different groups was compared. Correlation analysis between the expression of EGFR and the fluctuation value of fasting blood glucose (FBG) was carried out. Immunohistochemistry was used to detect the expression of EGFR in cancer tissues of patients with recurrent OSCC. These patients had normal blood glucose and took metformin for a long time after the first operation.

RESULTS

EGFR expression in T2DM patients with OSCC taking metformin was significantly lower than that in the non-metformin group. FBG fluctuations were positively correlated with the expression of EGFR in the OSCC tissues of the non-metformin group of T2DM patients. In patients with recurrent OSCC with normal blood glucose, metformin remarkably reduced the expression of EGFR in recurrent OSCC tissues.

CONCLUSION

Metformin may regulate the expression of EGFR in a way that does not rely on lowering blood glucose. These results may provide further evidence for metformin in the treatment of OSCC.