Increased expression of SRPK1 (serine/arginine-rich protein-specific kinase 1) is associated with progression and unfavorable prognosis in cervical squamous cell carcinoma

JAK2/ULK1 axis promotes cervical cancer progression by autophagy induction and SRPK1 phosphorylation

Cervical cancer is the most common gynecologic cancer. Autophagy is involved in the progression of CCa. ULK1 is a crucial kinase in autophagy initiation. However, few studies have investigated the role of ULK1 phosphorylation at tyrosine residues in the progression of CCa, and the underlying mechanism remains elusive. In this study, we demonstrated that JAK2 is a novel upstream kinase that phosphorylates ULK1 at the tyrosine site. JAK2 interacts with and phosphorylates ULK1 at Tyr1007. The phosphorylation of ULK1 at Y1007 increases its activity and stability, activates autophagy, and promotes the progression of CCa. We further showed that the phosphorylation of ULK1 at Y1007 is a predictive marker of CCa patient outcome. Furthermore, we identified SRPK1 as a potential downstream substrate of ULK1 to promote the progression of CCa. Our research sheds light on the molecular mechanism of CCa progression, through JAK2/ULK1 axis, and emphasizes the phosphorylation of ULK1 at Y1007 as a predictor of CCa.

SRPK1 Promotes Glioma Proliferation, Migration, and Invasion through Activation of Wnt/β-Catenin and JAK-2/STAT-3 Signaling Pathways

Currently, the treatment of gliomas still relies primarily on surgery and radiochemotherapy. Although there are various drugs available, including temozolomide, the overall therapeutic effect is unsatisfactory, and the prognosis remains poor. Therefore, the in-depth study of the mechanism of glioma development and a search for new therapeutic targets are the keys to improving the therapeutic treatment of gliomas and improving the prognosis of patients. Immunohistochemistry is used to detect the expression of relevant molecules in tissues, qPCR and Western blot are used to detect the mRNA and protein expression of relevant molecules, CCK-8 (Cell Counting Kit-8) is used to assess cell viability and proliferation capacity, Transwell is used to evaluate cell migration and invasion ability, and RNA transcriptome sequencing is used to identify the most influential pathways. SRPK1 (SRSF protein kinase 1) is highly expressed in gliomas but is not expressed in normal tissues. Its expression is positively correlated with the grades of gliomas and negatively correlated with prognosis. SRPK1 significantly promotes the occurrence and development of gliomas. Knocking down SRPK1 leads to a significant decrease in the proliferation, migration, and invasion abilities of gliomas. Loss of SRPK1 expression induces G2/M phase arrest and mitotic catastrophe, leading to apoptosis in cells. Overexpression of SRPK1 activates the Wnt/β-catenin (wingless-int1/β-catenin) and JAK-2/STAT-3 (Janus kinase 2/signal transducer and activator of transcription 3) signaling pathways, promoting the proliferation, migration, and invasion of gliomas. Overexpression of SRPK1 rescues the reduced cell proliferation, migration, and invasion abilities caused by the silencing of β-catenin or JAK-2. A stable shRNA-LN229 cell line was constructed, and using a nude mouse model, it was found that stable knockout of SRPK1 significantly reduced the tumorigenic ability of glioma cells, as evidenced by a significant decrease in the subcutaneous tumor volume and weight in nude mice. We have demonstrated that SRPK1 is highly expressed in gliomas. Overexpression of SRPK1 activates the Wnt/β-catenin and JAK-2/STAT-3 signaling pathways, promoting the proliferation, migration, and invasion of gliomas. Silencing SRPK1-related signaling pathways may provide potential therapeutic options for glioma patients.

SRPKs: a promising therapeutic target in cancer

Cancers such as lung, breast, colon, and prostate have been linked to dysregulation of SRPKs. In preclinical studies, inhibition of SRPKs has been shown to reduce the growth and survival of cancer cells, suggesting that SRPKs may be potential therapeutic targets. Research is ongoing to develop small molecule inhibitors of SRPKs, identify specific SRPKs that are important in different cancer types, and explore the use of RNA interference (RNAi) to target SRPKs. In addition, researchers are examining the potential of using SRPK inhibitors in combination with other cancer therapies, such as chemotherapy or immunotherapy, to improve treatment outcomes. However, more research is needed to fully understand the role of SRPKs in cancer and determine the most effective ways to target them. In the present review, we shed light on the role of SRPKs in most common cancers, its role in cancer resistance, and targeting it for cancer treatment.

RIPOR2 Expression Decreased by HPV-16 E6 and E7 Oncoproteins: An Opportunity in the Search for Prognostic Biomarkers in Cervical Cancer

High-risk human papillomavirus (HPV) infection is the main risk factor for cervical cancer (CC) development, where the continuous expression of E6 and E7 oncoproteins maintain the malignant phenotype. In Mexico, around 70% of CC cases are diagnosed in advanced stages, impacting the survival of patients. The aim of this work was to identify biomarkers affected by HPV-16 E6 and E7 oncoproteins that impact the prognosis of CC patients. Expression profiles dependent on E6 and E7 oncoproteins, as well as their relationship with biological processes and cellular signaling pathways, were analyzed in CC cells. A comparison among expression profiles of E6- and E7-expressing cells and that from a CC cohort obtained from The Cancer Genome Atlas (TCGA) demonstrated that the expression of 13 genes impacts the overall survival (OS). A multivariate analysis revealed that the downregulated expression of RIPOR2 was strongly associated with a worse OS. RIPOR2, including its transcriptional variants, were overwhelmingly depleted in E6- and E7-expressing cells. Finally, in a Mexican cohort, it was found that in premalignant cervical lesions, RIPOR2 expression decreases as the lesions progress; meanwhile, decreased RIPOR2 expression was also associated with a worse OS in CC patients.

Inhibition of SRPK1, a key splicing regulator, exhibits antitumor and chemotherapeutic-sensitizing effects on extranodal NK/T-cell lymphoma cells

BACKGROUND

Increasing evidence has convincingly shown that abnormal pre-mRNA splicing is implicated in the development of most human malignancies. Serine/arginine-rich protein kinase 1 (SRPK1), a key splicing regulator, is reported to be overexpressed in leukemia and other cancer types, which suggests the therapeutic potential of targeting SRPK1.

METHODS

SRPK1 expression was measured in 41 ENKTL patients by immunohistochemistry and mRNA expression was analyzed by qRT‒PCR. We knocked down SRPK1 expression in the ENKTL cell line YT by siRNA transfection and inhibited SRPK1 using inhibitors (SPHINX31 and SRPIN340) in YT cells and peripheral blood lymphocytes (PBLs) isolated from ENKTL patients to investigate its role in cell proliferation and apoptosis. Then, RNA-seq analysis was performed to predict the potential signaling pathway by which SRPK1 inhibition induces cell death and further verified this prediction by Western blotting.

RESULTS

In the present study, we initially evaluated the clinical significance of SRPK1 in extranodal natural killer/T-cell lymphoma (ENKTL), a very aggressive subtype of non-Hodgkin lymphoma. The expression of SRPK1 in ENKLT patients was examined by immunohistochemistry and qRT‒PCR, which revealed SRPK1 overexpression in more than 60% of ENKTL specimens and its association with worse survival. Cellular experiments using the human ENKTL cell line YT and PBLs from ENKTL patients, demonstrated that inhibition of SRPK1 suppressed cell proliferation and induced apoptosis. Subsequently, we investigated the downstream targets of SRPK1 by RNA-seq analysis and found that SRPK1 inhibition induced ATF4/CHOP pathway activation and AKT1 inhibition. Furthermore, ENKTL patients presenting high SRPK1 expression showed resistance to cisplatin-based chemotherapy. The association of SRPK1 expression with cisplatin resistance was also confirmed in YT cells. SRPK1 overexpression via pLVX-SRPK1 plasmid transfection dramatically decreased the sensitivity of YT cells to cisplatin, while siRNA-mediated SRPK1 knockdown or SRPK1 inhibitor treatment significantly increased cisplatin cytotoxicity.

CONCLUSION

In summary, these results support that SRPK1 might be a useful clinical prognostic indicator and therapeutic target for ENKTL, especially for patients who relapse after cisplatin-based chemotherapies.

Luteolin impacts deoxyribonucleic acid repair by modulating the mitogen-activated protein kinase pathway in colorectal cancer

This study aimed to investigate the effects of luteolin on colorectal cancer (CRC) and explore its underlying mechanism. HCT-116 and HT-29 cells were treated with luteolin, cisplatin, or selumetinib. The cell survival, cell proliferation, apoptosis and cell cycle distribution, and DNA damage were detected using Cell Counting Kit-8, colony formation, flow cytometry, and immunofluorescence staining analysis, respectively. Western blotting was used to detect the expression of apoptosis-related, cycle-related, DNA-damage-related, and mitogen-activated protein kinase (MAPK) pathway-related proteins. Luteolin showed inhibitory effects on cellular growth by reducing cell survival and proliferation, inducing apoptosis and DNA damage, and arresting the cell cycle in a concentration-dependent manner in HCT-116 and HT-29 cells. Meanwhile, luteolin increased the expression of pro-apoptotic proteins, p-CHK1 (central to the induction of cell cycle arrest), and DNA excision repair protein and decreased anti-apoptotic proteins, G2-M phase-related proteins, and DNA repair proteins. The combination of cisplatin and luteolin significantly decreased cell survival and increased the apoptosis rate of HCT-116 and HT-29 cells compared with cisplatin alone. Bioinformatic analysis using the Comparative Toxicogenomics Database and STITCH and MalaCards databases showed that the MAPK pathway is involved in the pharmacology of luteolin. Furthermore, western blotting demonstrated that luteolin plays an inhibitory role by suppressing the MAPK signaling pathway in CRC, which is enhanced when combined with selumetinib. Luteolin can also prevent tumourigenesis in CRC in vivo. In conclusion, luteolin suppressed cell proliferation, blocked the cell cycle, and induced DNA damage and apoptosis progression in CRC cells by mediating the MAPK pathway