Prognostic value of histone H3 serine 10 phosphorylation and histone H4 lysine 12 acetylation in oral squamous cell carcinoma

Lactylome analyses suggest systematic lysine-lactylated substrates in oral squamous cell carcinoma under normoxia and hypoxia

Cancer cells tend to live in hypoxic environment characterized by enhanced glycolysis and accumulation of lactate. Intracellular lactate is shown to drive a novel type of post-translational modification (PTM), lysine lactylation (Kla). Kla has been confirmed to affect the malignant progression of tumors such as hepatocellular carcinoma (HCC) and colon cancer, whereas the global lactylomic profiling of oral squamous cell carcinoma (OSCC) is unclear. Here, the integrative lactylome and proteome analyses by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) identified 1011 Kla sites within 532 proteins and 1197 Kla sites within 608 proteins in SCC25 cells under normoxic and hypoxic environments, respectively. Among these lactylated proteins, histones accounted for only a small fraction, suggesting the presence of Kla modification of OSCC in a large number of non-histone proteins. Notably, Kla preferred to enrich in spliceosome, ribosome and glycolysis/gluconeogenesis pathway in both normoxic and hypoxic cultures. Compared with normoxia, 589 differential proteins with 898 differentially lactylated sites were detected under hypoxia, which were mainly associated with the glycolysis/gluconeogenesis pathway by KEGG analysis. Importantly, we verified the presence of lactylation modification in the spliceosomal proteins hnRNPA1, SF3A1, hnRNPU and SLU7, as well as in glycolytic enzyme PFKP. In addition, the differential alternative splicing analysis described the divergence of pre-mRNA splicing patterns in the presence or absence of sodium lactate and at different oxygen concentrations. Finally, a negative correlation between tissue Kla levels and the prognosis of OSCC patients was revealed by immunohistochemistry. Our study is the first report to elucidate the lactylome and its biological function in OSCC, which deepens our understanding of the mechanisms underlying OSCC progression and provides a novel strategy for targeted therapy for OSCC.

Oral tumor heterogeneity, its implications for patient monitoring and designing anti-cancer strategies

Oral cancer tumors occur in the mouth and are mainly derived from oral mucosa linings. It is one of the most common and fatal malignant diseases worldwide. The intratumor heterogeneity (ITH) of oral cancerous tumor is vast, so it is challenging to study and interpret. Due to environmental selection pressures, ITH arises through diverse genetic, epigenetic, and metabolic alterations. The ITH also talks about peri-tumoral vascular/ lymphatic growth, perineural permeation, tumor necrosis, invasion, and clonal expansion/ the coexistence of multiple subclones in a single tumor. The heterogeneity offers tumors the adaptability to survive, induce growth/ metastasis, and, most importantly, escape antitumor therapy. Unfortunately, the ITH is prioritized less in determining disease pathology than the traditional TNM classifications or tumor grade. Understanding ITH is challenging, but with the advancement of technology, this ITH can be decoded. Tumor genomics, proteomics, metabolomics, and other modern analyses can provide vast information. This information in clinics can assist in understanding a tumor's severity and be used for diagnostic, prognostic, and therapeutic decision-making. Lastly, the oral tumor ITH can lead to individualized, targeted therapy strategies fighting against OC.

Correlation of H3K9ac and H4K12ac With Cell Proliferation Marker Ki-67 in Oral Leukoplakia: An Immunohistochemical Study

This study aimed to analyze the immunohistochemical expression of H3K9ac and H4K12ac in oral leukoplakia (OL) and its association with cell proliferation marker Ki-67 and clinicopathologic data. Paraffin-embedded, formalin-fixed tissue samples from 50 OLs and 15 fragments of the normal oral mucosa (NOM) were submitted to immunohistochemical assay using the streptavidin-biotin-peroxidase method. Quantitative analysis of the antigen-antibody reaction was performed by obtaining integrated optical density (IOD) and the percentage of positive nuclei (PPN) with ImageJ software. OL samples presented higher PPN ( P =0.02) and lower IOD values ( P =0.007) for H4K12ac in comparison to NOM. The area under the receiver operating characteristic curve for PPN and IOD values of H4K12ac immunostaining were 0.70 ( P =0.02) and 0.73 ( P =0.007), respectively. No differences were found between OL and NOM for H3K9ac. Cell proliferation marker Ki-67 had a positive correlation with PPN ( P <0.0001) and IOD ( P =0.0007) for H3K9ac expression and with IOD values ( P =0.002) for H4K12ac expression. The present findings suggest that alterations in the acetylation pattern of H4K12 occur in the early stages of oral carcinogenesis and that both H3K9ac and H4K12ac might have a role in the regulation of epithelial cell proliferation of OL.

miR-15a-5p inhibits metastasis and lipid metabolism by suppressing histone acetylation in lung cancer

Metabolic reprogramme was a key characteristic of malignant tumors. Increased evidences indicated that besides Warburg effect (abnormal glucose metabolism), abnormal lipid metabolism played more and more important in progression and metastasis of malignant tumors. MiR-15a-5p could inhibit development of lung cancer, while its regulating mechanism, especially the role in lipid metabolism still remained unclear. In this study, we confirmed that miR-15a-5p inhibited proliferation, migration and invasion of lung cancer cells. The online analysis of Mirpath v.3 predicted that miR-15a-5p was closely associated with fatty acid synthesis and lipid metabolism. In vitro cell experiments revealed that miR-15a-5p significantly suppressed fatty acid synthesis of lung cancer cells by inhibiting acetate uptake. Extensive analysis indicated that miR-15a-5p could suppress acetyl-CoA activity and decrease histone H4 acetylation by inhibiting ACSS2 expression. In addition, we also observed that ACSS2 located in nucleus under hypoxic conditions, while miR-15a-5p could be transported into nucleus to inhibit the function of ACSS2. Our study unveiled a novel mechanism of miR-15a-5p in inhibiting metastasis of lung cancer cells by suppressing lipid metabolism via suppression of ACSS2 mediated acetyl-CoA activity and histone acetylation.

The role of the histones H3K9ac, H3K9me3, HP1γ, and H3K36me3 in oral squamous cell carcinoma loco-regional metastasis and relapse

Molecular markers with unequivocal significance in predicting cervical lymph node metastasis of oral squamous cell carcinoma (OSCC) has not yet been identified. Histones are DNA-binding proteins that can regulate gene expression, and some studies have shown that such proteins are implicated with tumor development and progression. This study aimed to investigate the expression of some histone modifications in OSCC and their roles in cervical lymph node metastasis. To address this goal, H3K9ac, H3K9me3, HP1γ, and H3K36me3 expression levels were investigated immunohistochemically in a retrospective metastatic and non-metastatic OSCC samples. We analyzed the association between these markers with clinical-pathological data and survival rates. Hyperacetylation of H3K9ac was associated with cervical lymph node metastasis and local relapse. High expression levels of H3K9m3 were related to age and symptomatology. Furthermore, it was also found a statistically significant association between high HP1γ-expressing tumors and tumor size. However, no markers were associated with reduced overall survival rate. Our results suggest that covalent histone modifications contribute to OSCC behavior, and H3K9ac may play a critical role in OSCC-derived cervical lymph node metastasis.