METTL5 promotes gastric cancer progression via sphingomyelin metabolism.

BACKGROUND: The treatment of gastric cancer (GC) has caused an enormous social burden worldwide. Accumulating studies have reported that N6-methyladenosine (m6A) is closely related to tumor progression. METTL5 is a m6A methyltransferase that plays a pivotal role in maintaining the metabolic stability of cells. However, its aberrant regulation in GC has not been fully elucidated. AIM: To excavate the role of METTL5 in the development of GC. METHODS: METTL5 expression and clinicopathological characteristics were analyzed via The Cancer Genome Atlas dataset and further verified via immunohistochemistry, western blotting and real-time quantitative polymerase chain reaction in tissue microarrays and clinical samples. The tumor-promoting effect of METTL5 on HGC-27 and AGS cells was explored in vitro by Cell Counting Kit-8 assays, colony formation assays, scratch healing assays, transwell assays and flow cytometry. The tumor-promoting role of METTL5 in vivo was evaluated in a xenograft tumor model. The EpiQuik m6A RNA Methylation Quantification Kit was used for m6A quantification. Next, liquid chromatography-mass spectrometry was used to evaluate the association between METTL5 and sphingomyelin metabolism, which was confirmed by Enzyme-linked immunosorbent assay and rescue tests. In addition, we investigated whether METTL5 affects the sensitivity of GC cells to cisplatin via colony formation and transwell experiments. RESULTS: Our research revealed substantial upregulation of METTL5, which suggested a poor prognosis of GC patients. Increased METTL5 expression indicated distant lymph node metastasis, advanced cancer stage and pathological grade. An increased level of METTL5 correlated with a high degree of m6A methylation. METTL5 markedly promotes the proliferation, migration, and invasion of GC cells in vitro. METTL5 also promotes the growth of GC in animal models. METTL5 knockdown resulted in significant changes in sphingomyelin metabolism, which implies that METTL5 may impact the development of GC via sphingomyelin metabolism. In addition, high METTL5 expression led to cisplatin resistance. CONCLUSION: METTL5 was found to be an oncogenic driver of GC and may be a new target for therapy since it facilitates GC carcinogenesis through sphingomyelin metabolism and cisplatin resistance.

Bone metastases in oral squamous cell carcinoma: A real-world retrospective study based on the SEER database.

BACKGROUND: Bone metastases are rare in oral squamous cell carcinoma (OSCC). It has not been defined on the risk and prognosis of OSCC patients with bone metastases. The purpose of this study was to assess the factors associated with the development and prognosis of bone metastases among OSCC patients. METHODS: Demographic and clinicopathological characteristics of OSCC patients diagnosed between 2010 and 2019 was retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. To explore risk factors for developing bone metastases and prognosis, the univariate and multivariate logistic and Cox regression analysis were performed, further the predictive nomogram models were constructed. RESULTS: The incidence rate of bone metastases in newly diagnosed OSCC patients was 0.91 % (95 %CI 0.81% -1.02 %). Ultimately, 137 OSCC patients with bone metastases and 19,469 OSCC patients without bone metastases were included in the present study. Pathological grade, primary site, T/N stage and distant organ metastases (liver/lung/brain) were independently associated with the risk of developing bone metastases among OSCC patients. The C-index of a constructed risk-predicting nomogram was 0.86 (95 %CI 0.83-0.89). Multivariate Cox regression analysis indicated that lung metastases, the use of surgery as well as chemotherapy were three independent prognostic factors. The C-indexes of constructed risk-predicting nomograms were 0.70 (95 %CI 0.65-0.75), 0.68 (95 %CI 0.63-0.73) for OS and CSS, respectively. Calibration plots demonstrated an agreementbetween the established nomogram's predicted survival and actual survival. In addition, decision curve analysis (DCA) indicated these established nomograms had considerable net benefits and clinical utilities. CONCLUSION: This study defined the risk and prognostic factors for bone metastases among OSCC patients and the established nomograms were well calibrated for discrimination to predict bone metastasis development and prognosis.

Regioselective Diels-Alder Reactions of Anthracenes with Olefins via Visible Light Photocatalysis in a Homogeneous Solution.

Diels-Alder cycloaddition of anthracene with olefin is achieved in a homogeneous solution via energy transfer under visible light. A series of substrates including electroneutral styrene derivatives can be successfully converted into the corresponding cycloadducts in a head-to-head orientation with high to excellent yields. The high ortho-regioselectivity, mild condition, and broad substrate scope enable promising advances in organic transformation.