Effect of the intratumoral microbiota on spatial and cellular heterogeneity in cancer.

The tumour-associated microbiota is an intrinsic component of the tumour microenvironment across human cancer types1,2. Intratumoral host-microbiota studies have so far largely relied on bulk tissue analysis1-3, which obscures the spatial distribution and localized effect of the microbiota within tumours. Here, by applying in situ spatial-profiling technologies4 and single-cell RNA sequencing5 to oral squamous cell carcinoma and colorectal cancer, we reveal spatial, cellular and molecular host-microbe interactions. We adapted 10x Visium spatial transcriptomics to determine the identity and in situ location of intratumoral microbial communities within patient tissues. Using GeoMx digital spatial profiling6, we show that bacterial communities populate microniches that are less vascularized, highly immuno­suppressive and associated with malignant cells with lower levels of Ki-67 as compared to bacteria-negative tumour regions. We developed a single-cell RNA-sequencing method that we name INVADEseq (invasion-adhesion-directed expression sequencing) and, by applying this to patient tumours, identify cell-associated bacteria and the host cells with which they interact, as well as uncovering alterations in transcriptional pathways that are involved in inflammation, metastasis, cell dormancy and DNA repair. Through functional studies, we show that cancer cells that are infected with bacteria invade their surrounding environment as single cells and recruit myeloid cells to bacterial regions. Collectively, our data reveal that the distribution of the microbiota within a tumour is not random; instead, it is highly organized in microniches with immune and epithelial cell functions that promote cancer progression.

Mitochondrial RNA modifications shape metabolic plasticity in metastasis.

Aggressive and metastatic cancers show enhanced metabolic plasticity1, but the precise underlying mechanisms of this remain unclear. Here we show how two NOP2/Sun RNA methyltransferase 3 (NSUN3)-dependent RNA modifications-5-methylcytosine (m5C) and its derivative 5-formylcytosine (f5C) (refs.2-4)-drive the translation of mitochondrial mRNA to power metastasis. Translation of mitochondrially encoded subunits of the oxidative phosphorylation complex depends on the formation of m5C at position 34 in mitochondrial tRNAMet. m5C-deficient human oral cancer cells exhibit increased levels of glycolysis and changes in their mitochondrial function that do not affect cell viability or primary tumour growth in vivo; however, metabolic plasticity is severely impaired as mitochondrial m5C-deficient tumours do not metastasize efficiently. We discovered that CD36-dependent non-dividing, metastasis-initiating tumour cells require mitochondrial m5C to activate invasion and dissemination. Moreover, a mitochondria-driven gene signature in patients with head and neck cancer is predictive for metastasis and disease progression. Finally, we confirm that this metabolic switch that allows the metastasis of tumour cells can be pharmacologically targeted through the inhibition of mitochondrial mRNA translation in vivo. Together, our results reveal that site-specific mitochondrial RNA modifications could be therapeutic targets to combat metastasis.

Oral and non-oral lichen planus show genetic heterogeneity and differential risk for autoimmune disease and oral cancer.

Lichen planus (LP) is a T-cell-mediated inflammatory disease affecting squamous epithelia in many parts of the body, most often the skin and oral mucosa. Cutaneous LP is usually transient and oral LP (OLP) is most often chronic, so we performed a large-scale genetic and epidemiological study of LP to address whether the oral and non-oral subgroups have shared or distinct underlying pathologies and their overlap with autoimmune disease. Using lifelong records covering diagnoses, procedures, and clinic identity from 473,580 individuals in the FinnGen study, genome-wide association analyses were conducted on carefully constructed subcategories of OLP (n = 3,323) and non-oral LP (n = 4,356) and on the combined group. We identified 15 genome-wide significant associations in FinnGen and an additional 12 when meta-analyzed with UKBB (27 independent associations at 25 distinct genomic locations), most of which are shared between oral and non-oral LP. Many associations coincide with known autoimmune disease loci, consistent with the epidemiologic enrichment of LP with hypothyroidism and other autoimmune diseases. Notably, a third of the FinnGen associations demonstrate significant differences between OLP and non-OLP. We also observed a 13.6-fold risk for tongue cancer and an elevated risk for other oral cancers in OLP, in agreement with earlier reports that connect LP with higher cancer incidence. In addition to a large-scale dissection of LP genetics and comorbidities, our study demonstrates the use of comprehensive, multidimensional health registry data to address outstanding clinical questions and reveal underlying biological mechanisms in common but understudied diseases.

Loss of p53 drives neuron reprogramming in head and neck cancer.

The solid tumour microenvironment includes nerve fibres that arise from the peripheral nervous system1,2. Recent work indicates that newly formed adrenergic nerve fibres promote tumour growth, but the origin of these nerves and the mechanism of their inception are unknown1,3. Here, by comparing the transcriptomes of cancer-associated trigeminal sensory neurons with those of endogenous neurons in mouse models of oral cancer, we identified an adrenergic differentiation signature. We show that loss of TP53 leads to adrenergic transdifferentiation of tumour-associated sensory nerves through loss of the microRNA miR-34a. Tumour growth was inhibited by sensory denervation or pharmacological blockade of adrenergic receptors, but not by chemical sympathectomy of pre-existing adrenergic nerves. A retrospective analysis of samples from oral cancer revealed that p53 status was associated with nerve density, which was in turn associated with poor clinical outcomes. This crosstalk between cancer cells and neurons represents mechanism by which tumour-associated neurons are reprogrammed towards an adrenergic phenotype that can stimulate tumour progression, and is a potential target for anticancer therapy.

The inner mitochondrial membrane fission protein MTP18 serves as a mitophagy receptor to prevent apoptosis in oral cancer.

MTP18 (also known as MTFP1), an inner mitochondrial membrane protein, plays a vital role in maintaining mitochondrial morphology by regulating mitochondrial fission. Here, we found that MTP18 functions as a mitophagy receptor that targets dysfunctional mitochondria into autophagosomes for elimination. Interestingly, MTP18 interacts with members of the LC3 (also known as MAP1LC3) family through its LC3-interacting region (LIR) to induce mitochondrial autophagy. Mutation in the LIR motif (mLIR) inhibited that interaction, thus suppressing mitophagy. Moreover, Parkin or PINK1 deficiency abrogated mitophagy in MTP18-overexpressing human oral cancer-derived FaDu cells. Upon exposure to the mitochondrial oxidative phosphorylation uncoupler CCCP, MTP18[mLIR]-FaDu cells showed decreased TOM20 levels without affecting COX IV levels. Conversely, loss of Parkin or PINK1 resulted in inhibition of TOM20 and COX IV degradation in MTP18[mLIR]-FaDu cells exposed to CCCP, establishing Parkin-mediated proteasomal degradation of outer mitochondrial membrane as essential for effective mitophagy. We also found that MTP18 provides a survival advantage to oral cancer cells exposed to cellular stress and that inhibition of MTP18-dependent mitophagy induced cell death in oral cancer cells. These findings demonstrate that MTP18 is a novel mitophagy receptor and that MTP18-dependent mitophagy has pathophysiologic implications for oral cancer progression, indicating inhibition of MTP18-mitophagy could thus be a promising cancer therapy strategy.

Tumor Necrosis Factor α-Induced Protein 8-Like 1 Binds to Protein Arginine Methyltransferase 1 to Suppress the Methylation of Signal Transducer and Activator of Transcription 3 and Cell Growth in Oral Squamous Cell Carcinoma.

The tumor necrosis factor α-induced protein 8 (TIPE, also TNFAIP8 or OXi-α) family is a newly discovered series of proteins involved in immune regulation and tumorigenesis. TIPE1, a member of the TIPE/TNFAIP8/OXi-α family, has emerged as an anticancer-drug target, as it promotes cancer cell apoptosis and inhibits cell proliferation. The current study aimed to systematically reveal that TIPE1 regulates the activity of protein arginine methyltransferase (PRMT)-1 and the subsequent methylation of signal transducer and activator of transcription (STAT)-3 to suppress oral squamous cell carcinoma (OSCC) growth. TIPE1 was down-regulated in the OSCC cell lines (Tca8113, SCC25, Cal27, SCC15, and HSC27). TIPE1 overexpression significantly inhibited cell proliferation, colony formation, in vivo tumorgenicity, and Ki-67 expression in OSCC. TIPE1 interacted with the catalytic region of PRMT1 and inhibited STAT3 methylation. The effects of TIPE1 on OSCC cells were alleviated after PRMT1 overexpression, confirming the importance of this interaction to the tumor-suppressive effects of TIPE1. Together, these findings confirmed that TIPE1 mediated PRMT1 suppression through direct binding to its catalytic domain and subsequently inhibited the methylation and expression of STAT3 in OSCC cells, thereby inhibiting cell growth and tumorgenicity.

Targeting ENPP1 depletion may be a promising therapeutic strategy for treating oral squamous cell carcinoma via cytotoxic autophagy-related apoptosis.

ENPP1 depletion closely related with modulation immunotherapy of several types of cancer. However, the role of ENPP1 correlation with autophagy in oral squamous cell carcinoma (OSCC) pathogenesis remain unknown. In this study, effects of ENPP1 on OSCC cells in vitro were examined by cell proliferation assay, transwell chamber assay, flow cytometry analysis and shRNA technique. Cellular key proteins related to cell autophagy and apoptosis were evaluated by Western blot and immunofluorescent staining. Moreover, functions of ENPP1 on OSCC process were observed in nude mouse model. We reported that overexpression of ENPP1 promote the growth of OSCC cell xenografts in nude mouse model. In contrast, ENPP1 downregulation significantly inhibits OSCC cancer growth and induces apoptosis both in vitro and in vivo, which are preceded by cytotoxic autophagy. ENPP1downregulation induces a robust accumulation of autophagosomes, increases LC3B-II and decreases SQSTM1/p62 in ENPP1-shRNA-treated cells and xenografts. Mechanistic studies show that ENPP1 downregulation increases PRKAA1 phosphorylation leading to ULK1 activation. AMPK-inhibition abrogates ENPP1 downregulation-induced ULK1-activation, LC3B-turnover and SQSTM1/p62-degradation while AMPK-activation potentiates it's effects. Collectively, these data uncover that ENPP1 downregulation induces autophagic cell death in OSCC cancer, which may provide a potential therapeutic target for the treatment of OSCC.

LAMA3 Promotes Tumorigenesis of Oral Squamous Cell Carcinoma by METTL3-Mediated N6-Methyladenosine Modification.

Laminin subunit alpha 3 (LAMA3) is a cancer regulator. However, its effects and regulatory pathways in oral squamous cell carcinoma (OSCC) progression remain unknown. This research aimed to determine the influence of LAMA3 regulation via methyltransferase-like 3 (METTL3) on OSCC progression. Using quantitative real-time polymerase chain reaction and bioinformatics analysis, the expression levels of LAMA3 and METTL3 in OSCC tissues were examined. The functional roles of LAMA3 and METTL3 were analyzed using cell functional experiments. Using methylated RNA immunoprecipitation and mRNA stability assays, LAMA3 and METTL3 regulation was investigated. In OSCC tissues, LAMA3 was upregulated. LAMA3 inhibition hampered OSCC cell proliferation, invasion, and migration while its overexpression facilitated OSCC cell progression. METTL3 serves as a crucial upstream regulator of LAMA3 in OSCC and upregulates LAMA3 expression via an m6A-dependent mechanism. The low METTL3 expression partially restored the enhanced malignant phenotype induced by LAMA3 overexpression. Our findings indicate that METTL3 and LAMA3 act as pro-oncogenic factors in OSCC, with METTL3 promoting OSCC malignancy via m6A modification-dependent stabilization of LAMA3 transcripts, representing a novel regulatory mechanism in OSCC.

The competitive mechanism of EZH1 and EZH2 in promoting oral squamous cell carcinoma.

Enhancer of Zeste Homolog 1 (EZH1) and Enhancer of Zeste Homolog 2 (EZH2) are the key components of polycomb repressive complex 2 (PRC2); however, the roles of these proteins in oral squamous cell carcinoma (OSCC) have yet to be elucidated. In this study, we aimed to determine the respective roles of these proteins in OSCC by investigating the expression levels of EZH1 and EZH2 in OSCC tissues (N = 63) by immunohistochemistry. In addition, we used lentiviruses to construct stable OSCC cell lines that overexpressed EZH1 and EZH2. Then, we investigated these cell lines for cell viability, colony formation capacity, stemness, and epithelial-mesenchymal transition (EMT). Binding competition between EZH1 and EZH2 with PRC2 was further evaluated using Co-immunoprecipitation (Co-IP). Compared with normal tissues, the expression levels of EZH2 in OSCC tissues was up-regulated, while the expression of EZH1 was down-regulated. EZH2 enhanced cell viability, colony formation capacity, stemness, and EMT, while EZH1 did not. Furthermore, analysis indicated that EZH1 and EZH2 bound competitively to PRC2 and influenced the methylation status of H3K27. In conclusion, our findings verified that EZH1 and EZH2 play opposing roles in OSCC and that EZH1 and EZH2 compete as the key component of PRC2, thus affecting the characteristics of OSCC via the methylation of H3K27.

CLSPN actives Wnt/ß-catenin signaling to facilitate glycolysis and cell proliferation in oral squamous cell carcinoma.

OBJECTIVE: Oral squamous cell carcinoma (OSCC) is a common malignancy with a poor prognosis. This study aimed to determine the influence and underlying mechanisms of CLSPN on OSCC. METHODS: CLSPN expression was tested using quantitative real-time polymerase chain reaction, immunohistochemistry, and western blotting. Flow cytometry, cell counting kit, and colony formation assays were performed to determine OSCC cell apoptosis, viability, and proliferation, respectively. In OSCC cells, the extracellular acidification rate (ECAR), oxygen consumption rate (OCR), glucose uptake, and lactate production were determined using the corresponding kits. Changes in the protein levels of HK2, PKM2, LDHA, Wnt3a, and ß-catenin were assessed using western blotting. RESULTS: CLSPN expression was increased in OSCC tissues. Overexpression of CLSPN in HSC-2 cells promoted cell proliferation, increased the levels of ECAR, glucose uptake, and lactate production, and increased the protein levels of HK2, PKM2, LDHA, Wnt3a, and ß-catenin, but inhibited OCR levels and apoptosis. The knockdown of CLSPN in CAL27 cells resulted in the opposite results. Moreover, the effects of CLSPN overexpression on glycolysis and OSCC cell proliferation were reversed by Wnt3a knockdown. In vivo, knockdown of CLSPN restrained tumor growth, glycolysis, and the activation of Wnt/ß-catenin signaling. CONCLUSION: CLSPN promoted glycolysis and OSCC cell proliferation, and reduced apoptosis, which was achieved by the activation of Wnt/ß-catenin signaling pathway.

EphA2 promotes the transcription of KLF4 to facilitate stemness in oral squamous cell carcinoma.

Ephrin receptor A2 (EphA2), a member of the Ephrin receptor family, is closely related to the progression of oral squamous cell carcinoma (OSCC). Cancer stem cells (CSCs) play essential roles in OSCC development and occurrence. The underlying mechanisms between EphA2 and CSCs, however, are not yet fully understood. Here, we found that EphA2 was overexpressed in OSCC tissues and was associated with poor prognosis. Knockdown of EphA2 dampened the CSC phenotype and the tumour-initiating frequency of OSCC cells. Crucially, the effects of EphA2 on the CSC phenotype relied on KLF4, a key transcription factor for CSCs. Mechanistically, EphA2 activated the ERK signalling pathway, promoting the nuclear translocation of YAP. Subsequently, YAP was bound to TEAD3, leading to the transcription of KLF4. Overall, our findings revealed that EphA2 can enhance the stemness of OSCC cells, and this study identified the EphA2/KLF4 axis as a potential target for treating OSCC.

Role of E2F transcription factor in oral cancer: Recent insight and advancements.

The family of mammalian E2F transcription factors (E2Fs) comprise of 8 members (E2F1-E2F8) classified as activators (E2F1-E2F3) and repressors (E2F4-E2F8) primarily regulating the expression of several genes related to cell proliferation, apoptosis and differentiation, mainly in a cell cycle-dependent manner. E2F activity is frequently controlled via the retinoblastoma protein (pRb), cyclins, p53 and the ubiquitin-proteasome pathway. Additionally, genetic or epigenetic changes result in the deregulation of E2F family genes expression altering S phase entry and apoptosis, an important hallmark for the onset and development of cancer. Although studies reveal E2Fs to be involved in several human malignancies, the mechanisms underlying the role of E2Fs in oral cancer lies nascent and needs further investigations. This review focuses on the role of E2Fs in oral cancer and the etiological factors regulating E2Fs activity, which in turn transcriptionally control the expression of their target genes, thus contributing to cell proliferation, metastasis, and drug/therapy resistance. Further, we will discuss therapeutic strategies for E2Fs, which may prevent oral tumor growth, metastasis, and drug resistance.

TLR9 activation induces immunosuppression and tumorigenesis via PARP1/PD-L1 signaling pathway in oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer, and metastasis and immunosuppression are responsible for the poor prognosis of OSCC. Previous studies have shown that poly(ADP-ribose) polymerase (PARP)1 plays a key role in the pathogenesis of OSCC. Therefore, PARP1 may serve as an important research target for the potential treatment of OSCC. Here, we aimed to investigate the role of PARP1 in the tumorigenesis of OSCC and elucidate the key molecular mechanisms of its upstream and downstream regulation in vivo and in vitro. In human OSCC tissues and cells, Toll-like receptor (TLR)9 and PD-L1 were highly expressed and PARP1 was lowly expressed. Suppression of TLR9 remarkably repressed CAL27 and SCC9 cell proliferation, migration, and invasion. After coculture, we found that low expression of TLR9 inhibited PD-L1 expression and immune escape. In addition, TLR9 regulated PD-L1 expression through the PARP1/STAT3 pathway. PARP1 mediated the effects of TLR9 on OSCC cell proliferation, migration, and invasion and immune escape. Additionally, in vivo experiments further verified that TLR9 promoted tumor growth and immune escape by inhibiting PARP1. Collectively, TLR9 activation induced immunosuppression and tumorigenesis via PARP1/PD-L1 signaling pathway in OSCC, providing important insights for subsequent in-depth exploration of the mechanism of OSCC.NEW & NOTEWORTHY In this research, we took PARP1 as the key target to explore its regulatory effect on oral squamous cell carcinoma (OSCC). The key molecular mechanisms involved in its upstream and downstream regulation were elucidated in OSCC cell lines in vitro and tumor-bearing mice in vivo, combined with clinical OSCC tissues.

Splicing factor ESRP1 derived circ_0068162 promotes the progression of oral squamous cell carcinoma via the miR-186/JAG axis.

OBJECTIVES: Oral squamous cell carcinoma (OSCC) is a common malignancy in the oral and maxillofacial regions with an increasing incidence rate. Circular RNA (circRNA) is a recently discovered long-chain non-coding RNA family member. The objective of this study was to analyze the role of circ_0068162 in OSCC development. METHODS: We downloaded sample data GSE145608 from the Gene Expression Omnibus database. Online databases Starbase, TargetScan and miRDB were used to predict the target microRNAs (miRNAs) and genes. Cell viability and proliferation were assessed using the CCK-8 and EdU assays, respectively. Cell migration and invasion abilities were detected using transwell assay. The double luciferase reporter and RNA immunoprecipitation (RIP) assays were performed to verify the interaction relationship between the identified target molecules. RNase R and actinomycin D treatment were performed to analyze the stability of circ_0068162. RESULTS: We found that circ_0068162 was overexpressed in the cytoplasm of OSCC cells and clinical OSCC tissues. Knockdown of circ_0068162 inhibited the growth, migration and invasion of OSCC cells. We also identified miR-186 as the target miRNA of circ_0068162, and JAG1 and JAG2 as the target genes of miR-186. The miR-186 inhibitor rescued the effects of sh-circ_0068162 and JAG1/JAG2 overexpression rescued the effects of miR-186 mimic in OSCC cells. Furthermore, ESRP1 promoted the biosynthesis of circ_0068162. CONCLUSIONS: The circ_0068162/miR-186/JAGs/ESRP1 feedback loop is closely related to OSCC development.

Hellebrigenin induces oral cancer cell apoptosis by modulating MAPK signalling and XIAP expression.

Oral squamous cell carcinoma (OSCC), which accounts for 90% of all oral cancers, has become a public health crisis worldwide. despite advances in therapeutic interventions, the prognosis remains poor for advanced-stage OSCC. In this study, we investigate the anticancer activity and the mode of action of hellebrigenin in human OSCC. The findings demonstrated that hellebrigenin exerted cytotoxic effects in OSCC cells through cell cycle arrest at the G2/M phase and downregulation of cell cycle-related proteins (cyclins A2, B1 and D3, Cdc2, CDK4 and CDK6). Moreover, hellebrigenin caused activation of PARP and caspase 3, 8 and 9, followed by downregulation of antiapoptotic proteins (Bcl-2 and Bcl-xL) and upregulation of pro-apoptotic proteins (Bax and Bak). The hellebrigenin treatment also increased Fas, DR5, DcR2 and DcR3 expressions in oral cancer cells, indicating the compound causes oral cancer cell apoptosis through both intrinsic and extrinsic pathways. Regarding upstream signalling, hellebrigenin was found to reduce the phosphorylation of ERK, p38, and JNK, indicating that hellebrigenin triggers caspase-mediated apoptosis by downregulating MAPK signalling pathway. Finally, the human apoptosis array findings revealed that hellebrigenin specifically suppressed the expression of XIAP to execute its pro-apoptotic activities. Taken together, the study suggests that hellebrigenin can act as a potent anticancer compound in human OSCC.

Up-regulation of TNF-alpha/NFkB/SIRT1 axis drives aggressiveness and cancer stem cells accumulation in chemoresistant oral squamous cell carcinoma.

Tumor resistance remains an obstacle to successfully treating oral squamous cell carcinoma (OSCC). Cisplatin is widely used as a cytotoxic drug to treat solid tumors, including advanced OSCC, but with low efficacy due to chemoresistance. Therefore, identifying the pathways that contribute to chemoresistance may show new possibilities for improving the treatment. This work explored the role of the tumor necrosis factor-alpha (TNF-alpha)/NFkB signaling in driving the cisplatin resistance of OSCC and its potential as a pharmacological target to overcome chemoresistance. Differential accessibility analysis demonstrated the enrichment of opened chromatin regions in members of the TNF-alpha/NFkB signaling pathway, and RNA-Seq confirmed the upregulation of TNF-alpha/NFkB signaling in cisplatin-resistant cell lines. NFkB was accumulated in cisplatin-resistant cell lines and in cancer stem cells (CSC), and the administration of TNF-alpha increased the CSC, suggesting that TNF-alpha/NFkB signaling is involved in the accumulation of CSC. TNF-alpha stimulation also increased the histone deacetylases HDAC1 and SIRT1. Cisplatin-resistant cell lines were sensitive to the pharmacological inhibition of NFkB, and low doses of the NFkB inhibitors, CBL0137, and emetine, efficiently reduced the CSC and the levels of SIRT1, increasing histone acetylation. The NFkB inhibitors decreased stemness potential, clonogenicity, migration, and invasion of cisplatin-resistant cell lines. The administration of the emetine significantly reduced the tumor growth of cisplatin-resistant xenograft models, decreasing NFkB and SIRT1, increasing histone acetylation, and decreasing CSC. TNF-alpha/NFkB/SIRT1 signaling regulates the epigenetic machinery by modulating histone acetylation, CSC, and aggressiveness of cisplatin-resistant OSCC and the NFkB inhibition is a potential strategy to treat chemoresistant OSCC.

DNMT1-targeting remodeling global DNA hypomethylation for enhanced tumor suppression and circumvented toxicity in oral squamous cell carcinoma.

BACKGROUND: The faithful maintenance of DNA methylation homeostasis indispensably requires DNA methyltransferase 1 (DNMT1) in cancer progression. We previously identified DNMT1 as a potential candidate target for oral squamous cell carcinoma (OSCC). However, how the DNMT1- associated global DNA methylation is exploited to regulate OSCC remains unclear. METHODS: The shRNA-specific DNMT1 knockdown was employed to target DNMT1 on oral cancer cells in vitro, as was the use of DNMT1 inhibitors. A xenografted OSCC mouse model was established to determine the effect on tumor suppression. High-throughput microarrays of DNA methylation, bulk and single-cell RNA sequencing analysis, multiplex immunohistochemistry, functional sphere formation and protein immunoblotting were utilized to explore the molecular mechanism involved. Analysis of human samples revealed associations between DNMT1 expression, global DNA methylation and collaborative molecular signaling with oral malignant transformation. RESULTS: We investigated DNMT1 expression boosted steadily during oral malignant transformation in human samples, and its inhibition considerably minimized the tumorigenicity in vitro and in a xenografted OSCC model. DNMT1 overexpression was accompanied by the accumulation of cancer-specific DNA hypomethylation during oral carcinogenesis; conversely, DNMT1 knockdown caused atypically extensive genome-wide DNA hypomethylation in cancer cells and xenografted tumors. This novel DNMT1-remodeled DNA hypomethylation pattern hampered the dual activation of PI3K-AKT and CDK2-Rb and inactivated GSK3ß collaboratively. When treating OSCC mice, targeting DNMT1 achieved greater anticancer efficacy than the PI3K inhibitor, and reduced the toxicity of blood glucose changes caused by the PI3K inhibitor or combination of PI3K and CDK inhibitors as well as adverse insulin feedback. CONCLUSIONS: Targeting DNMT1 remodels a novel global DNA hypomethylation pattern to facilitate anticancer efficacy and minimize potential toxic effects via balanced signaling synergia. Our study suggests DNMT1 is a crucial gatekeeper regarding OSCC destiny and treatment outcome.

Inhibition of transforming growth factor-ß signals suppresses tumor formation by regulation of tumor microenvironment networks.

The tumor microenvironment (TME) consists of cancer cells surrounded by stromal components including tumor vessels. Transforming growth factor-ß (TGF-ß) promotes tumor progression by inducing epithelial-mesenchymal transition (EMT) in cancer cells and stimulating tumor angiogenesis in the tumor stroma. We previously developed an Fc chimeric TGF-ß receptor containing both TGF-ß type I (TßRI) and type II (TßRII) receptors (TßRI-TßRII-Fc), which trapped all TGF-ß isoforms and suppressed tumor growth. However, the precise mechanisms underlying this action have not yet been elucidated. In the present study, we showed that the recombinant TßRI-TßRII-Fc protein effectively suppressed in vitro EMT of oral cancer cells and in vivo tumor growth in a human oral cancer cell xenograft mouse model. Tumor cell proliferation and angiogenesis were suppressed in tumors treated with TßRI-TßRII-Fc. Molecular profiling of human cancer cells and mouse stroma revealed that K-Ras signaling and angiogenesis were suppressed. Administration of TßRI-TßRII-Fc protein decreased the expression of heparin-binding epidermal growth factor-like growth factor (HB-EGF), interleukin-1ß (IL-1ß) and epiregulin (EREG) in the TME of oral cancer tumor xenografts. HB-EGF increased proliferation of human oral cancer cells and mouse endothelial cells by activating ERK1/2 phosphorylation. HB-EGF also promoted oral cancer cell-derived tumor formation by enhancing cancer cell proliferation and tumor angiogenesis. In addition, increased expressions of IL-1ß and EREG in oral cancer cells significantly enhanced tumor formation. These results suggest that TGF-ß signaling in the TME controls cancer cell proliferation and angiogenesis by activating HB-EGF/IL-1ß/EREG pathways and that TßRI-TßRII-Fc protein is a promising tool for targeting the TME networks.

LINC00629, a HOXB4-downregulated long noncoding RNA, inhibits glycolysis and ovarian cancer progression by destabilizing c-Myc.

Ovarian cancer (OC) cells typically reprogram their metabolism to promote rapid proliferation. However, the role of long noncoding RNAs (lncRNAs) in the metabolic reprogramming of ovarian cancer, especially in glucose metabolic reprogramming, remains largely unknown. LINC00629 has been reported in our previous study to promote osteosarcoma progression. Upregulated LINC00629 was found to enhance the growth-suppressive effect of apigenin on oral squamous cell carcinoma. However, the precise function of LINC00629 in ovarian cancer development remains poorly understood. In this study, we found that LINC00629 was significantly downregulated in OC tissues and that low LINC00629 expression was associated with poor survival. Inhibition of LINC00629 was required for increased glycolysis activity and cell proliferation in ovarian cancer. In vivo, overexpression of LINC00629 dramatically inhibited tumor growth and lung metastasis. Mechanistically, LINC00629 interacted with and destabilized c-Myc, leading to its ubiquitination and proteasome degradation, further resulting in increased expression of downstream glycolysis-related genes and glucose metabolic reprogramming in OC. Interestingly, HOXB4 bound to the LINC00629 promoter and inhibited its transcription, indicating that LINC00629 is a transcriptional target of HOXB4. Collectively, these findings establish a direct role for LINC00629 in suppressing glucose metabolism, and HOXB4/LINC00629/c-Myc might serve as a potential biomarker and an effective therapeutic strategy for OC cancer treatment.

Antiapoptotic PON2 expression and its clinical implications in locally advanced oral squamous cell carcinoma.

Locally advanced oral squamous cell carcinoma poses a significant challenge in oncology due to its rising incidence and mortality rates. Despite therapeutic progress, understanding molecular intricacies is essential. This study explored the role of PON2, a multifunctional enzyme implicated in antiapoptotic mechanisms. Aberrant PON2 expression in oral cancers raises questions regarding its involvement in evading programmed cell death and treatment resistance. Patients with locally advanced disease were enrolled, and molecular analyses were undertaken on the collected tumor and normal tissues. Utilizing computational datasets, this study used in silico gene expression analysis, differential gene expression analysis in our patient cohort, survival analysis, and gene set enrichment analysis to unravel role of PON2 in disease prognosis. The results showed elevated PON2 levels in advanced tumor stages, correlating with factors such as tobacco exposure, higher tumor grade, and nodal metastasis. Survival analysis revealed prognostic relevance of PON2, with lower expression linked to extended survival rates. Gene set enrichment analysis identified pathways aiding in cancer metastasis influenced by PON2. This study underscores the significance of PON2 expression as a prognostic marker for oral malignancies, with increased expression associated with advanced disease stages. Understanding the molecular profile of the PON2 gene suggests its potential as a valuable biomarker for the management of cancer.