Ovarian cancer is the most lethal malignancy affecting the female reproductive system. Pharmacological inhibitors targeting CDK4/6 have demonstrated promising efficacy across various cancer types. However, their clinical benefits in ovarian cancer patients fall short of expectations, with only a subset of patients experiencing these advantageous effects. This study aims to provide further clinical and biological evidence for antineoplastic effects of a CDK4/6 inhibitor (TQB4616) in ovarian cancer and explore underlying mechanisms involved. Patient-derived ovarian cancer organoid models were established to evaluate the effectiveness of TQB3616. Potential key genes related to TQB3616 sensitivity were identified through RNA-seq analysis, and TRIM4 was selected as a candidate gene for further investigation. Subsequently, co-immunoprecipitation and GST pull-down assays confirmed that TRIM4 binds to hnRNPDL and promotes its ubiquitination through RING and B-box domains. RIP assay demonstrated that hnRNPDL binded to CDKN2C isoform 2 and suppressed its expression by alternative splicing. Finally, in vivo studies confirmed that the addition of siTRIM4 significantly improved the effectiveness of TQB3616. Overall, our findings suggest that TRIM4 modulates ubiquitin-mediated degradation of hnRNPDL and weakens sensitivity to CDK4/6 inhibitors in ovarian cancer treatment. TRIM4 may serve as a valuable biomarker for predicting sensitivity to CDK4/6 inhibitors in ovarian cancer.
Humans ; Female ; Ovarian Neoplasms/pathology* ; Animals ; Tripartite Motif Proteins/genetics* ; Mice ; Cyclin-Dependent Kinase 4/antagonists & inhibitors* ; Cell Line, Tumor ; Cyclin-Dependent Kinase 6/antagonists & inhibitors* ; Protein Kinase Inhibitors/pharmacology* ; Ubiquitin/metabolism* ; Xenograft Model Antitumor Assays ; Ubiquitination ; Antineoplastic Agents/pharmacology*

Cyclin-dependent kinases 4/6 (CDK4/6) inhibitors are anti-tumor agents for the treatment of hormone receptor-positive breast cancer. Palbociclib, abemaciclib and dalpiciclib have been approved for the treatment of breast cancer in China. Common adverse effects of CDK4/6 inhibitors include bone marrow suppression, gastrointestinal toxicities, liver dysfunction, and skin or subcutaneous tissue adverse reactions (AEs). The Breast Cancer Expert Group of Chinese Society of Clinical Oncology (CSCO) summarized the incidence, clinical manifestations, and grading of the AEs. This expert consensus reports measures of AE management on the basis of experience of clinical practice and the latest advances worldwide, aiming to guide clinical practice by the way of managing AE and help to choose the best treatment regimen.
Female ; Humans ; Aminopyridines/adverse effects* ; Antineoplastic Agents/adverse effects* ; Breast Neoplasms/drug therapy* ; Consensus ; Cyclin-Dependent Kinase 4/antagonists & inhibitors* ; Protein Kinase Inhibitors/adverse effects* ; Cyclin-Dependent Kinase 6/antagonists & inhibitors*

Osteosarcoma is the most common primary sarcoma of bone, and it is a leading cause of cancer death among adolescents and young adults. However, the molecular mechanism underlying osteosarcoma carcinogenesis remains poorly understood. Recently, cyclin-dependent kinase 6 (CDK6) was identified as an important oncogene. We found that CDK6 protein level, rather than CDK6 mRNA level, is much higher in osteosarcoma tissues than in normal adjacent tissues, which indicates a post-transcriptional mechanism involved in CDK6 regulation in osteosarcoma. MiRNAs are small non-coding RNAs that repress gene expression at the post-transcriptional level and have widely been shown to play important roles in many human cancers. In this study, we investigated the role of miR-29b as a novel regulator of CDK6 using bioinformatics methods. We demonstrated that CDK6 can be downregulated by miR-29b via binding to the 3'-UTR region in osteosarcoma cells. Furthermore, we identified an inverse correlation between miR-29b and CDK6 protein levels in osteosarcoma tissues. Finally, we examined the function of miR-29b-driven repression of CDK6 expression in osteosarcoma cells. The results revealed that miR-29b acts as a tumor suppressor of osteosarcoma by targeting CDK6 in the proliferation and migration processes. Taken together, our results highlight an important role for miR-29b in the regulation of CDK6 in osteosarcoma and may open new avenues for future osteosarcoma therapies.
3' Untranslated Regions ; Animals ; Base Sequence ; Bone Neoplasms ; metabolism ; pathology ; Cell Line, Tumor ; Cell Movement ; Cell Proliferation ; Cyclin-Dependent Kinase 6 ; antagonists & inhibitors ; genetics ; metabolism ; Humans ; Mice ; MicroRNAs ; metabolism ; Osteosarcoma ; metabolism ; pathology ; RNA Interference ; RNA, Messenger ; metabolism ; RNA, Small Interfering ; metabolism ; Rats ; Sequence Alignment ; Up-Regulation

OBJECTIVETo investigate the effects of bromodomain-containing protein 4 (BRD4) inhibitor GSK525762A on the proliferation and apoptosis of primary common B-cell acute lymphoblastic leukemia (common B-ALL) cells from adult patients, then to further explore the possible mechanisms.

METHODSPurified leukemia cells from 14 common B-ALL adult patients (4 Ph⁺ and 10 Ph⁻ cases) were obtained by flow cytometry sorting, and maintained in a mimic bone marrow microenvironment culture system for short-term culture. Leukemia cells were treated with various concentrations of GSK525762A. The inhibitory effects of BRD4 inhibitor on common B-ALL leukemia cells were measured by CCK-8 assay and the apoptosis of those cells was determined by AnnexinⅤ/7-AAD staining using flow cytometry. The transcripts of c-MYC, CDK6 and Bcl-2 were detected by quantitative RT-PCR, and the expression of c-MYC, CDK6 and Bcl-2 proteins were detected via Western blot.

RESULTSGSK525762A could inhibit the proliferation of leukemia cells from all 14 common B-ALL patients in a dose-dependent manner, the median value of IC50 was 256.25 (90.64-1 378.39)nmol/L. GSK525762A could promote cells apoptosis of B-ALL leukemia cells in a dose-dependent manner, the median apoptosis rates respectively were 45.17%(9.38%-70.91%), 66.02% (24.36%-96.34%) and 89.29% (39.29%-99.37%) after treated by 500, 1 000 and 2 500 nmol/L GSK525762A. GSK525762A has a similar effect on Ph⁺ ALL and Ph⁻ B-ALL, but the effect of proliferation inhibition and apoptosis enhancement on Ph+ B-ALL is weaker than that on Ph⁻ B-ALL. Compared with vehicle control group, the levels of c-MYC, Bcl-2 and CDK6 transcripts in leukemic cells were reduced after treatment for 24 h and 48 h by 1 000 nmol/L GSK525762A, and there are no significant differences in the downregulation of c-MYC and CDK6 mRNA between Ph⁺ and Ph⁻ B-ALL; however, the inhibitory effect on Bcl-2 transcription was weaker in Ph⁺ B-ALL cells than that in Ph⁻ B-ALL cells. Moreover, c-MYC, Bcl-2 and CDK6 protein levels decreased in GSK525762A treated group.

CONCLUSIONGSK525762A could strongly inhibit the proliferation of common B-ALL and trigger apoptosis; meanwhile it has certain effects against Ph⁺ ALL in vitro. The effect may be achieved by down-regulation of c-MYC, CDK6 and Bcl-2 expression.

Apoptosis ; Benzodiazepines ; pharmacology ; Cell Line, Tumor ; drug effects ; Cyclin-Dependent Kinase 6 ; metabolism ; Down-Regulation ; Flow Cytometry ; Humans ; Nuclear Proteins ; antagonists & inhibitors ; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma ; pathology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Proto-Oncogene Proteins c-myc ; metabolism ; Transcription Factors ; antagonists & inhibitors