The cyclin-dependent kinase 11 interacts with 14-3-3 proteins

Transcriptional activation of CBFβ by CDK11p110 is necessary to promote osteosarcoma cell proliferation

BACKGROUND

Aberrant expression of cyclin-dependent protein kinases (CDK) is a hallmark of cancer. CDK11 plays a crucial role in cancer cell growth and proliferation. However, the molecular mechanisms of CDK11 and CDK11 transcriptionally regulated genes are largely unknown.

METHODS

In this study, we performed a global transcriptional analysis using gene array technology to investigate the transcriptional role of CDK11 in osteosarcoma. The promoter luciferase assay, chromatin immunoprecipitation assay, and Gel Shift assay were used to identify direct transcriptional targets of CDK11. Clinical relevance and function of core-binding factor subunit beta (CBFβ) were further accessed in osteosarcoma.

RESULTS

We identified a transcriptional role of protein-DNA interaction for CDK11p110, but not CDK11p58, in the regulation of CBFβ expression in osteosarcoma cells. The CBFβ promoter luciferase assay, chromatin immunoprecipitation assay, and Gel Shift assay confirmed that CBFβ is a direct transcriptional target of CDK11. High expression of CBFβ is associated with poor outcome in osteosarcoma patients. Expression of CBFβ contributes to the proliferation and metastatic behavior of osteosarcoma cells.

CONCLUSIONS

These data establish CBFβ as a mediator of CDK11p110 dependent oncogenesis and suggest that targeting the CDK11- CBFβ pathway may be a promising therapeutic strategy for osteosarcoma treatment.

CDK11 Loss Induces Cell Cycle Dysfunction and Death of BRAF and NRAS Melanoma Cells

Cyclin dependent kinase 11 (CDK11) is a protein kinase that regulates RNA transcription, pre-mRNA splicing, mitosis, and cell death. Targeting of CDK11 expression levels is effective in the experimental treatment of breast and other cancers, but these data are lacking in melanoma. To understand CDK11 function in melanoma, we evaluated protein and RNA levels of CDK11, Cyclin L1 and Cyclin L2 in benign melanocytes and BRAF- as well as NRAS-mutant melanoma cell lines. We investigated the effectiveness of reducing expression of this survival kinase using RNA interference on viability, clonal survival, and tumorsphere formation in melanoma cell lines. We examined the impact of CDK11 loss in BRAF-mutant melanoma on more than 700 genes important in cancer signaling pathways. Follow-up analysis evaluated how CDK11 loss alters cell cycle function in BRAF- and NRAS-mutant melanoma cells. We present data on CDK11, CCNL1 and CCNL2 mRNA expression in melanoma patients, including prognosis for survival. In sum, we found that CDK11 is necessary for melanoma cell survival, and a major impact of CDK11 loss in melanoma is to cause disruption of the cell cycle distribution with accumulation of G1- and loss of G2/M-phase cancer cells.

Increased Sat2 expression is associated with busulfan-induced testicular Sertoli cell injury

Busulfan is a chemotherapeutic agent used to treat chronic myelogenous leukemia and other myeloproliferative disorders. Increasing evidence has demonstrated that busulfan may induce testicular dysfunction by targeting genes that are expressed in the testis. Here, we showed that spermidine/spermine N1-acetyltransferase 2 (Sat2) was present in testicular Sertoli cells, and its expression was significantly increased by busulfan treatment. To investigate the implications of Sat2 upregulation for cell growth and function, a Sat2-overexpressing TM4 Sertoli cell model was established. Increased Sat2 expression led to inhibited cell proliferation and arrested cell cycle. Based on iTRAQ proteomics analysis, we revealed that Sat2 overexpression is detrimental to cell cycle progression and cell communication, and notably, Sat2 may disturb protein metabolic processes by altering translation regulation and protein complex subunit organization. In summary, the present study provides evidence that Sat2 upregulation induces alterations in the growth and function of Sertoli cells. In testis tissue subjected to busulfan, increased expression of Sat2 can cause cellular injury and subsequent organ damage, which could lead to male infertility. Therefore, Sat2 may be a novel molecular target for treating busulfan-induced testicular toxicity.

The emerging roles and therapeutic potential of cyclin-dependent kinase 11 (CDK11) in human cancer

Overexpression and/or hyperactivation of cyclin-dependent kinases (CDKs) are common features of most cancer types. CDKs have been shown to play important roles in tumor cell proliferation and growth by controlling cell cycle, transcription, and RNA splicing. CDK4/6 inhibitor palbociclib has been recently approved by the FDA for the treatment of breast cancer. CDK11 is a serine/threonine protein kinase in the CDK family and recent studies have shown that CDK11 also plays critical roles in cancer cell growth and proliferation. A variety of genetic and epigenetic events may cause universal overexpression of CDK11 in human cancers. Inhibition of CDK11 has been shown to lead to cancer cell death and apoptosis. Significant evidence has suggested that CDK11 may be a novel and promising therapeutic target for the treatment of cancers. This review will focus on the emerging roles of CDK11 in human cancers, and provide a proof-of-principle for continued efforts toward targeting CDK11 for effective cancer treatment.

Cyclin-Dependent Kinase 11 (CDK11) Is Required for Ovarian Cancer Cell Growth In Vitro and In Vivo, and Its Inhibition Causes Apoptosis and Sensitizes Cells to Paclitaxel

Ovarian cancer is currently the most lethal gynecologic malignancy with limited treatment options. Improved targeted therapies are needed to combat ovarian cancer. Here, we report the identification of cyclin-dependent kinase 11 (CDK11) as a mediator of tumor cell growth and proliferation in ovarian cancer cells. Although CDK11 has not been implicated previously in this disease, we have found that its expression is upregulated in human ovarian cancer tissues and associated with malignant progression. Metastatic and recurrent tumors have significantly higher CDK11 expression when compared with the matched, original primary tumors. RNAi-mediated CDK11 silencing by synthetic siRNA or lentiviral shRNA decreased cell proliferation and induced apoptosis in ovarian cancer cells. Moreover, CDK11 knockdown enhances the cytotoxic effect of paclitaxel to inhibit cell growth in ovarian cancer cells. Systemic in vivo administration of CDK11 siRNA reduced the tumor growth in an ovarian cancer xenograft model. Our findings suggest that CDK11 may be a promising therapeutic target for the treatment of ovarian cancer patients. Mol Cancer Ther; 15(7); 1691-701. ©2016 AACR.

Cyclin-dependent kinase 11(p110) (CDK11(p110)) is crucial for human breast cancer cell proliferation and growth

Cyclin-dependent kinases (CDKs) play important roles in the development of many types of cancers by binding with their paired cyclins. However, the function of CDK11 larger protein isomer, CDK11(p110), in the tumorigenesis of human breast cancer remains unclear. In the present study, we explored the effects and molecular mechanisms of CDK11(p110) in the proliferation and growth of breast cancer cells by determining the expression of CDK11(p110) in breast tumor tissues and examining the phenotypic changes of breast cancer cells after CDK11(p110) knockdown. We found that CDK11(p110) was highly expressed in breast tumor tissues and cell lines. Tissue microarray analysis showed that elevated CDK11(p110) expression in breast cancer tissues significantly correlated with poor differentiation, and was also associated with advanced TNM stage and poor clinical prognosis for breast cancer patients. In vitro knockdown of CDK11(p110) by siRNA significantly inhibited cell growth and migration, and dramatically induced apoptosis in breast cancer cells. Flow cytometry demonstrated that cells were markedly arrested in G1 phase of the cell cycle after CDK11(p110) downregulation. These findings suggest that CDK11(p110) is critical for the proliferation and growth of breast cancer cells, which highlights CDK11(p110) may be a promising therapeutic target for the treatment of breast cancer.

Shotgun proteomic analysis on the diapause and non-diapause eggs of domesticated silkworm Bombyx mori

To clarify the molecular mechanisms of silkworm diapause, it is necessary to investigate the molecular basis at protein level. Here, the spectra of peptides digested from silkworm diapause and non-diapause eggs were obtained from liquid chromatography tandem mass spectrometry (LC-MS/MS) and were analyzed by bioinformatics methods. A total of 501 and 562 proteins were identified from the diapause and non-diapause eggs respectively, of which 309 proteins were shared commonly. Among these common-expressed proteins, three main storage proteins (vitellogenin precursor, egg-specific protein and low molecular lipoprotein 30 K precursor), nine heat shock proteins (HSP19.9, 20.1, 20.4, 20.8, 21.4, 23.7, 70, 90-kDa heat shock protein and heat shock cognate protein), 37 metabolic enzymes, 22 ribosomal proteins were identified. There were 192 and 253 unique proteins identified in the diapause and non-diapause eggs respectively, of which 24 and 48 had functional annotations, these unique proteins indicated that the metabolism, translation of the mRNA and synthesis of proteins were potentially more highly represented in the non-dipause eggs than that in the diapause eggs. The relative mRNA levels of four identified proteins in the two kinds of eggs were also compared using quantitative reverse transcription PCR (qRT-PCR) and showed some inconsistencies with protein expression. GO signatures of 486 out of the 502 and 545 out of the 562 proteins identified in the diapause and non-diapause eggs respectively were available. In addition, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed the Metabolism, Translation and Transcription pathway were potentially more active in the non-dipause eggs at this stage.

Systematic kinome shRNA screening identifies CDK11 (PITSLRE) kinase expression is critical for osteosarcoma cell growth and proliferation

PURPOSE

Identification of new targeted therapies is critical to improving the survival rate of patients with osteosarcoma. The goal of this study is to identify kinase based potential therapeutic target in osteosarcomas.

EXPERIMENTAL DESIGN

We used a lentiviral-based shRNA kinase library to screen for kinases which play a role in osteosarcoma cell survival. The cell proliferation assay was used to evaluate cell growth and survival. siRNA assays were applied to confirm the observed phenotypic changes resulting from the loss of kinase gene expression. CDK11 (PITSLRE) was identified as essential for the survival of osteosarcoma cells, and its expression was confirmed by Western blot analysis and immunohistochemistry. Overall patient survival was correlated with the CDK11 expression and its prognosis. The role of CDK11 expression in sustaining osteosarcoma growth was further evaluated in an osteosarcoma xenograft model in vivo.

RESULTS

Osteosarcoma cells display high levels of CDK11 expression. CDK11 expression knocked down by either lentiviral shRNA or siRNA inhibit cell growth and induce apoptosis in osteosarcoma cells. Immunohistochemical analysis showed that patients with osteosarcoma with high CDK11 tumor expression levels were associated with significantly shorter survival than patients with osteosarcoma with low level of tumor CDK11 expression. Systemic in vivo administration of in vivo ready siRNA of CDK11 reduced the tumor growth in an osteosarcoma subcutaneous xenograft model.

CONCLUSIONS

We show that CDK11 signaling is essential in osteosarcoma cell growth and survival, further elucidating the regulatory mechanisms controlling the expression of CDK11 and ultimately develop a CDK11 inhibitor that may provide therapeutic benefit against osteosarcoma.

Proteomic dissection of agonist-specific TLR-mediated inflammatory responses on macrophages at subcellular resolution

Upon stimulation by distinct bacterial/viral products/agonists, APCs including macrophages tend to express particular TLR molecules to coordinate the signaling that ultimately target at chromatin and mediate the activity of downstream transcriptional factors in regulating characteristic sets of gene expression for innate immune response. To investigate largely unknown regulatory mechanism underlying agonist-specific TLR-mediated innate immune responses, at subcellular resolution, we first analyzed Pam3CSK4-induced proteome changes in living macrophages and identified the differentially expressed proteins in the cytosol and chromatin-associated fractions, respectively, by using AACT/SILAC-based quantitative proteomic approach. In the cytosol fraction, we found that the proteins with notable Pam3CSK4-induced expression changes were primarily involved in post-translational events, energy metabolism, protein transporting, and apoptosis. Among them, a ubiquitous and highly conserved iron-binding protein, Ferritin, was further characterized as a modulator for the expression of a TLR2-specific cytokine IL-10 in murine macrophage cells by using small-interfering RNA (siRNA). Interestingly, we simultaneously identified multiple apoptosis-related proteins showing opposite trend in their regulated expressions, which clearly indicated the existence of systems regulation in differentially modulating the signal for the cross-road balance between protecting cell from apoptosis and the apoptosis of infected cells. For those regulated proteins identified in the nuclear fraction, we integrated bioinformatics to find the interactions of certain chromatin-associated proteins, which suggested their interconnected involvements in proteasome-ubiquitin pathway, DNA replication, and post-translational activity upon Pam3CSK4 stimulation. Certain regulated proteins in our quantitative proteomic data set showed the similar trend of up-regulation in both Pam3CSK4- and LPS-stimulated macrophages (Nature 2007, 447, 972), suggesting their belonging to the recently identified class of pro-inflammatory genes. The regulatory discrepancy between both data sets for other set of genes indicated their agonist-specific nature in innate immune responses.