Fat mass and obesity-associated protein (FTO) is an N6-methyladenosine (m6A) demethylase and plays critical oncogenic roles in multiple cancers. Here we show that FTO is an effective target in hepatocellular carcinoma (HCC). FTO is highly expressed in patients with HCC. Genetic depletion of Fto dramatically attenuated HCC progression in mice. Pharmacological inhibition of FTO by FB23/FB23-2 markedly suppressed the proliferation and migration of HCC cell lines in vitro and inhibited HCC tumorigenicity in xeno-transplanted mice. Mechanistically, FB23-2 suppressed the expression of Erb-b2 receptor tyrosine kinase 3 (ERBB3) and human tubulin beta class Iva (TUBB4A) by increasing the m6A level in these mRNA transcripts. The decrease in ERBB3 expression resulted in the inhibition of Akt-mTOR signaling, which subsequently impaired the proliferation and survival of HCC cells. Moreover, FB23-2 disturbed the stability of the tubulin cytoskeleton, whereas overexpression of TUBB4A rescued the migration of HCC cells. Collectively, our study demonstrates that FTO plays a critical role in HCC by maintaining the proliferation and migration of cells and highlights the potential of FTO inhibitors for targeting HCC.

Background: Melanoma is one of the most malignant skin carcinomas with high metastatic potential. Increasing evidence has demonstrated that β-tubulin 4A (TUBB4A) plays a key role in the development and progression of several types of human cancer. However, the potential function of TUBB4A in cutaneous melanoma remains to be determined. Methods: We first performed a differential expression analysis based on skin melanoma tissues and normal tissues from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) datasets and then a survival analysis to identify prognostic-related key genes. We further conducted in vitro biochemical experiments to verify the functional roles of the key gene TUBB4A. Two small-molecule inhibitors of TUBB4A, Dihydroartemisinin (DHA) and Nocodazole, were used to validate the effect of TUBB4A on the apoptosis and cell cycle of melanoma cells. Results: We found that TUBB4A expression was positively correlated to the overall survival (OS) of cutaneous melanoma patients. The coexpressed genes with TUBB4A were enriched in melanoma-related pathways and functions. The experimental results showed that knockdown of TUBB4A inhibited the proliferation and migration of A375 and B16-F10 melanoma cells. Moreover, DHA and Nocodazole promoted the apoptosis of melanoma cells and blocked the melanoma tumor cell cycle in the G2/M stage. Conclusion: TUBB4A may be a prognostic biomarker and therapeutic target for melanoma.

OBJECTIVE: Skin cutaneous melanoma(SKCM) is the most severe, and complex disease of all skin cancers. The molecular mechanisms of this cancer progression are not well understood.
METHODS: GEPIA online database was used to validate the differentially expressed genes from two GEO datasets. The prognostic value was calculated by the Kaplan-Meier method. RT-qPCR verified the expression of TUBB4A in SKCM cell line, and the immunohistochemistry of TUBB4A in SKCM and normal skin tissues were gained from Human Protein Atlas. Seven target prediction databases predicted potential microRNAs(miRNAs), and upstream long non-coding RNAs(lncRNAs) were predicted by starBase. The co-expressed gene of TUBB4A was obtained using the two online analysis sites UALCAN and starBase. These co-expressed genes were performed by enrichment analysis, and immune infiltration result was obtained by the TIMER2 online database. The receiver operating characteristic( ROC) curve was applied to evaluate the diagnostic value of TUBB4A in the SKCM and normal skin group. A new nomogram about TUBB4A was constructed to forecast the survival rate of SKCM patients at 1, 3, and 5 years.
RESULTS: Firstly, we found that DLL3 and TUBB4A were significantly higher expressed in skin cutaneous melanoma than normal skin. Subsequently, by analyzing progress-free interval(PFI), diseasespecific survival(DSS), and disease-free survival(DFS), only TUBB4A was the most potent gene for inhibiting shin cutaneous melanoma progression. In gene ontology(GO)/ kyoto encyclopedia of genes and genomes(KEGG) analysis, TUBB4A may play a key role in the progression of skin cutaneous melanoma by regulating mitochondrial function and affecting cellular metabolism, possibly related to the immune infiltration of CD4+Th1 cells and NK cells. The upstream non-coding RNA(ncRNA) acts through the SNHG16-hsa-let-7b-5p-TUBB4A axis.
CONCLUSIONS: In conclusion, we elucidated the regulatory role of the SNHG16-hsa-let-7b-5p-TUBB4A axis in the progression of skin cutaneous melanoma by modulating mitochondrial function to affect cellular metabolism. TUBB4A may be a promising diagnostic biomarker and therapeutic target for cutaneous skin melanoma.

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Dominant TUBB4A variants result in different phenotypes, including hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC), dystonia type 4 (DYT4), and isolated hypomyelination. Here, we report four new patients with a novel TUBB4A variant (p.K324T) and three new patients with previously reported variants (p.Q292K, p.V255I, p.E410K). The individual carrying the novel p.K324T variant exhibits epilepsy of infancy with migrating focal seizures (EIMFS), while the other three have isolated hypomyelination phenotype. We also present a study of the cellular effects of TUBB4A variants responsible for H-ABC (p.D249N), DYT4 (p.R2G), a severe combined phenotype with combination of hypomyelination and EIMFS (p.K324T), and isolated hypomyelination (p.Q292K and p.E410K) on microtubule stability and dynamics, neurite outgrowth, dendritic spine development, and kinesin binding. Cellular-based assays reveal that all variants except p.R2G increase microtubule stability, decrease microtubule polymerization rates, reduce axonal outgrowth, and alter the density and shape of dendritic spines. We also find that the p.K324T and p.E410K variants perturb the binding of TUBB4A to KIF1A, a neuron-specific kinesin required for transport of synaptic vesicle precursors. Taken together, our data suggest that impaired microtubule stability and dynamics, defected axonal growth, and dendritic spine development form the common molecular basis of TUBB4A-related leukodystrophy. Impairment of TUBB4A binding to KIF1A is more likely to be involved in the isolated hypomyelination phenotype, which suggests that alterations in kinesin binding may cause different phenotypes. In conclusion, our study extends the spectrum of TUBB4A mutations and related phenotypes and provides insight into why different TUBB4A variants cause distinct clinical phenotypes.