Overexpression of dual-specificity phosphatases 4 and 13 attenuates transforming growth factor β1-induced migration and drug resistance in A549 cells in vitro

Itraconazole Reversing Acquired Resistance to Osimertinib in NSCLC by Inhibiting the SHH/DUSP13B/p-STAT3 Axis

There is an urgent necessity to devise efficient tactics to tackle the inevitable development of resistance to osimertinib, which is a third-generation epidermal growth factor receptor (EGFR) inhibitor used in treating EGFR-mutant nonsmall cell lung cancer (NSCLC). This study demonstrates that combining itraconazole with osimertinib synergistically reduces the proliferation and migration, enhances the apoptosis of osimertinib-resistant cells, and effectively inhibits the growth of osimertinib-resistant tumors. Mechanistically, itraconazole combined with osimertinib promotes the proteasomal degradation of sonic hedgehog (SHH), resulting in inactivation of the SHH/Dual-specificity phosphatase 13B (DUSP13B)/p-STAT3 and Hedgehog pathways, suppressing Myc proto-oncogene protein (c-Myc). Additionally, DUSP13B interacts with signal transducer and activator of transcription 3 (STAT3) and modulates its phosphorylation. Interestingly, it is observed that SHH overexpression partially rescues the synergistic effects of this combination treatment strategy through the SHH/DUSP13B/p-STAT3 signaling axis. Moreover, it is found that SHH, (GLI1), p-STAT3, and DUSP13B play significant predictive roles in osimertinib resistance. In lung adenocarcinoma, p-STAT3 is positively correlated with SHH but negatively correlated with DUSP13B. Together, these results highlight the crucial role of itraconazole in reversing the acquired resistance to osimertinib and provide a scientific rationale for the therapeutic strategy of combining osimertinib with itraconazole.

The Strong Activation of p53 Tumor Suppressor Drives the Synthesis of the Enigmatic Isoform of DUSP13 Protein

The p53 tumor suppressor protein activates various sets of genes depending on its covalent modifications, which are controlled by the nature and intensity of cellular stress. We observed that actinomycin D and nutlin-3a (A + N) collaborate in inducing activating phosphorylation of p53. Our recent transcriptomic data demonstrated that these substances strongly synergize in the upregulation of DUSP13, a gene with an unusual pattern of expression, coding for obscure phosphatase having two isoforms, one expressed in the testes and the other in skeletal muscles. In cancer cells exposed to A + N, DUSP13 is expressed from an alternative promoter in the intron, resulting in the expression of an isoform named TMDP-L1. Luciferase reporter tests demonstrated that this promoter is activated by both endogenous and ectopically expressed p53. We demonstrated for the first time that mRNA expressed from this promoter actually produces the protein, which can be detected with Western blotting, in all examined cancer cell lines with wild-type p53 exposed to A + N. In some cell lines, it is also induced by clinically relevant camptothecin, by nutlin-3a acting alone, or by a combination of actinomycin D and other antagonists of p53-MDM2 interaction-idasanutlin or RG7112. This isoform, fused with green fluorescent protein, localizes in the perinuclear region of cells.

Expression of dual-specificity phosphatases in TGFß1-induced EMT in SKOV3 cells

BACKGROUND

The study aims to profile the dual-specificity phosphatases (DUSP) expression in response to Transforming growth factor β1 (TGFβ1)-induced epithelial- mesenchymal transition (EMT) in ovarian adenocarcinoma cells.

METHODS

The ovarian adenocarcinoma cell line SKOV3 was used as a TGFβ1-induced EMT model. Cells were incubated with 5 ng/mL TGFβ1 to induce EMT. EMT was confirmed with real-time qPCR, western blot, and immunofluorescence analyses of various EMT markers. Western blot was used to analyze phospho- and total MAPK protein levels. Typical and atypical DUSPs mRNA expression profile was determined by real-time qPCR.

RESULTS

The epithelial marker E-cadherin expressions were decreased and mesenchymal EMT markers Snail and Slug expression levelswere increased after TGFβ1 induction. Phosphorylation of ERK1/2 and p38 MAPK were enhanced in response to TGFβ1 treatment. The expression of DUSP2, DUSP6, DUSP8, DUSP10, and DUSP13 were decreased while DUSP7, DUSP16, DUSP18, DUSP21, and DUSP27 were increased by TGFβ1.

DISCUSSION

TGFβ1 induced EMT which was accompanied by increased activity of MAPKs, and led to marked changes in expressions of several DUSPs in SKOV3 cells.

Systemic analysis identifying PVT1 / DUSP13 axis for microvascular invasion in hepatocellular carcinoma

BACKGROUND

Microvascular invasion (MVI) is an independent detrimental risk factor for tumor recurrence and poor survival in hepatocellular carcinoma (HCC). Competitive endogenous RNA (ceRNA) networks play a pivotal role in the modulation of carcinogenesis and progression among diverse tumor types. However, whether the ceRNA mechanisms are engaged in promoting the MVI process in patients with HCC remains unknown.

METHODS

A ceRNA regulatory network was constructed based on RNA-seq data of patients with HCC from The Cancer Genome Atlas (TCGA) database. In total, 10 hub genes of the ceRNA network were identified using four algorithms: "MCC," "Degree," "Betweenness," and "Stress." Transcriptional expressions were verified by in situ hybridization using clinical samples. Interactions between ceRNA modules were validated by luciferase reporting assay. Logistic regression analysis, correlation analysis, enrichment analysis, promoter region analysis, methylation analysis, and immune infiltration analysis were performed to further investigate the molecular mechanisms and clinical transformation value.

RESULTS

The ceRNA regulatory network featuring a tumor invasion phenotype consisting of 3 long noncoding RNAs, 3 microRNAs, and 93 mRNAs was constructed using transcriptional data from the TCGA database. Systemic analysis and experimentally validation identified a ceRNA network (PVT1/miR-1258/DUSP13 axis) characterized by lipid regulatory potential, immune properties, and abnormal methylation states in patients with HCC and MVI. Meanwhile, 28 transcriptional factors were identified as potential promotors of PVT1 with 3 transcriptional factors MXD3, ZNF580, and KDM1A promising as therapeutic targets in patients with HCC and MVI. Furthermore, miR-1258 was an independent predictor for MVI in patients with HCC.

CONCLUSION

The PVT1/DUSP13 axis is significantly associated with MVI progression in HCC patients. This study provides new insight into mechanisms related to lipids, immune phenotypes, and abnormal epigenetics in oncology research.

Upregulation of dual-specificity phosphatase-26 is required for transforming growth factor β1(TGFβ1)-induced Epithelial-mesenchymal transition in A549 and PANC1 cells

BACKGROUND

Transforming Growth Factor β (TGFβ) proteins are potent inducers of the epithelial-mesenchymal transition (EMT) in tumor cells. Although mitogen-activated protein kinase (MAPK) family has been shown to be involved in TGFβ-induced EMT, role of Dual Specificity Phosphatases (DUSP), key regulators of MAPK activity, in TGFβ-induced EMT is largely unkonwn.

METHODS AND RESULTS

Real-time qPCR analyses were performed to determine the effect of TGFβ1 on expression of EMT genes and DUSP proteins in the non-small cell lung cancer model A549 and pancreatic adenocarcinoma model PANC1 cells. Western blot analyses were conducted to study the changes in protein levels of EMT proteins and select DUSP proteins, as well as phosphorylations of MAPK proteins upon TGFβ1 stimulation. Small interfering RNA (siRNA) was utilized to reduce expressions of DUSP genes. We observed that the EMT phenotype coincided with increases in phosphorylations of the MAPK proteins ERK1/2, p38MAPK, and JNK upon TGFβ1 stimulation. Real-time qPCR analysis showed increases in DUSP15 and DUSP26 mRNA levels and Western blot analysis confirmed the increase in DUSP26 protein levels in both A549 and PANC1 cells treated with TGFβ1 relative to control. Silencing of DUSP26 expression by siRNA markedly suppressed the effect of TGFβ1 on E-cadherin and mesenchymal genes in the cells.

CONCLUSIONS

Data provided suggest that TGFβ1 modulates the expression of DUSP genes and that upregulation of DUSP26 may be required for TGFβ1-promoted EMT in A549 and PANC1 cells. Further studies should be carried out to elucidate the requirement of individual DUSPs in TGFβ1-associated EMT in tumor cells.