RNAi-mediated downregulation of cyclin Y to attenuate human breast cancer cell growth

The role of cyclin Y in normal and pathological cells

The family protein of cyclins, as well as cyclin-dependent kinases (CDKs) cooperating with them, are broadly researched, as a matter of their dysfunction may lead to tumor transformation. Cyclins are defined as key regulators that have a controlling function of the mammalian nuclear cell divides. Cyclin Y (CCNY) is a recently characterized member of the cyclin family and was first identified from the human testis cDNA library. It is an actin-binding protein acting through decreased actin dynamics at a steady state and during glycine-induced long-term potentiation (LTP) and involves the inhibition of cofilin activation. What is more, CCNY is a positive regulatory subunit of the CDK14/PFTK1 complexes affected by the activation of the Wnt signaling pathway in the G2/M phase by recruiting CDK14/PFTK1 to the plasma membrane and promoting phosphorylation of LRP6. The expression of CCNY has been significantly mentioned within the cell migration and invasion activity both in vivo and in vitro. The aim of this review is evaluation of the expression of CCNY in the physiology processes and compare the expression of this protein in cancer cells, taking into account the impact of the level of expression on tumor progression.

CDK16 promotes the progression and metastasis of triple-negative breast cancer by phosphorylating PRC1

Background

Cyclin-dependent kinase 16 (CDK16) is an atypical PCTAIRE kinase, and its activity is dependent on the Cyclin Y (CCNY) family. Ccnys have been reported to regulate mammary stem cell activity and mammary gland development, and CCNY has been recognized as an oncoprotein in various cancers, including breast cancer. However, it remains unclear whether CDK16 has a role in breast cancer and whether it can be used as a therapeutic target for breast cancer.

Methods

Publicly available breast cancer datasets analyses and Kaplan-Meier survival analyses were performed to reveal the expression and clinical relevance of atypical CDKs in breast cancer. CDK16 protein expression was further examined by immunohistochemical and immunoblot analyses of clinical samples. Cell proliferation was measured by colony formation and MTT analyses. Cell cycle and apoptosis were examined by fluorescence-activated cell sorting (FACS) analysis. Wound-healing and trans-well invasion assays were conducted to test cell migration ability. The functions of CDK16 on tumorigenesis and metastasis were evaluated by cell line-derived xenograft, patient-derived organoid/xenograft, lung metastasis and systemic metastasis mouse models. Transcriptomic analysis was performed to reveal the potential molecular mechanisms involved in the function of CDK16. Pharmacological inhibition of CDK16 was achieved by the small molecular inhibitor rebastinib to further assess the anti-tumor utility of targeting CDK16.

Results

CDK16 is highly expressed in breast cancer, particularly in triple-negative breast cancer (TNBC). The elevated CDK16 expression is correlated with poor outcomes in breast cancer patients. CDK16 can improve the proliferation and migration ability of TNBC cells in vitro, and promote tumor growth and metastasis of TNBC in vivo. Both genetic knockdown and pharmacological inhibition of CDK16 significantly suppress the tumor progression of TNBC. Mechanistically, CDK16 exerts its function by phosphorylating protein regulator of cytokinesis 1 (PRC1) to regulate spindle formation during mitosis.

Conclusion

CDK16 plays a critical role in TNBC and is a novel promising therapeutic target for TNBC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02362-w.

Proteomic analysis of inhibitor of apoptosis protein‑like protein‑2 on breast cancer cell proliferation

Although inhibitor of apoptosis protein-like protein-2 (ILP-2) is considered to be a novel enhancer of breast cancer proliferation, its underlying mechanism of action remains unknown. Therefore, the present study aimed to investigate the expression profile of ILP-2-related proteins in MCF-7 cells to reveal their effect on promoting breast cancer cell proliferation. The isobaric tags for relative and absolute quantification (iTRAQ) method was used to analyse the expression profile of ILP-2-related proteins in MCF-7 breast cancer cells transfected with small interfering (si)RNA against ILP-2 (siRNA-5 group) and the negative control (NC) siRNA. The analysis of the iTRAQ data was carried out using western blotting and reverse transcription-quantitative PCR. A total of 4,065 proteins were identified in MCF-7 cells, including 241 differentially expressed proteins (DEPs; fold change ≥1.20 or ≤0.83; P<0.05). Among them, 156 proteins were upregulated and 85 were downregulated in the siRNA-5 group compared with in the NC group. The aforementioned DEPs were mainly enriched in ‘ECM-receptor interaction’. In addition, the top 10 biological processes related to these proteins were associated with signal transduction, cell proliferation and immune system processes. Furthermore, ILP-2 silencing upregulated N(4)-(β-N-acetylglucosaminyl)-L-asparaginase, metallothionein-1E and tryptophan 2,3-dioxygenase, whereas ILP-2 overexpression exerted the opposite effect. The results of the present study suggested that ILP-2 could promote breast cancer growth via regulating cell proliferation, signal transduction, immune system processes and other cellular physiological activities.

Cytoplasmic Localization Isoform of Cyclin Y Enhanced the Metastatic Ability of Lung Cancer via Regulating Tropomyosin 4

Cyclin Y (CCNY) is a novel cyclin and highly conserved in metazoan species. Previous studies from our and other laboratory indicate that CCNY play a crucial role in tumor progression. There are two CCNY isoform which has different subcellular distributions, with cytoplasmic isoform (CCNYc) and membrane distribution isoform (CCNYm). However, the expression and function of CCNY isoforms is still unclear. We firstly found CCNYc was expressed in natural lung cancer tissue and cells through the subcellular distribution. Co-IP and immunofluorescence showed that both CCNYm and CCNYc could interact with PFTK1. Further studies illustrated that CCNYc but not CCNYm enhanced cell migration and invasion activity both in vivo and vitro. The function of CCNYc could be inhibited by suppression of PFTK1 expression. In addition, our data indicated that tropomyosin 4 (TPM4), a kind of actin-binding proteins, was down-regulated by suppression of CCNY. F-actin assembly could be controlled by CCNYc as well as PFTK1 and TPM4. As a result, CCNY was mainly expressed in lung cancer. CCNYc could promote cell motility and invasion. It indicated that CCNYc/PFTK1 complex could promote cell metastasis by regulating the formation of F-actin via TPM4.

Cyclin Y binds and activates CDK4 to promote the G1/S phase transition in hepatocellular carcinoma cells via Rb signaling

Inactivation of Rb is a major event in the development of hepatocellular carcinoma (HCC). The activity of CDK4, determined by T172 phosphorylation, correlates with the onset of RB phosphorylation and G1/S cell cycle transition. However, the regulation of CDK4 activation and of the Rb pathway in HCC remain unclear. Here, we report that cyclin Y, a novel member of the cyclin family, is a potential regulator of the Rb pathway. We demonstrate that the Cyclin Y protein was overexpressed in human HCC tissues and that it was associated with poor patient prognosis. Cyclin Y could regulate the G1/S phase transition in human HCC cell lines. We found that CDK4 can bind to Cyclin Y in vitro. Furthermore, the accumulation of Cyclin Y could activate CDK4 through T172 phosphorylation of CDK4, inactivate Rb with increasing Rb phosphorylation, and enable the expression of E2F target genes such as CDK2 and Cyclin A. Thus, our findings suggest that Cyclin Y plays a role in the G1/S phase transition of HCC cells via Cyclin Y/CDK4/Rb signaling and that Cyclin Y could be used as a potential prognostic biomarker in HCC.

CCNY Accelerates Cylcin E Expression to Regulate the Proliferation of Laryngeal Carcinoma Cells via MEK/ERK Signaling Pathway

Background

Laryngeal carcinoma is a common cancer among head and neck tumors, accounting for 0.5–1% new cancer cases or deaths of all tumors throughout the body. Despite improvements in diagnostic and therapy, the prognosis of laryngeal carcinoma patients still remains poor. Thus, it is very important to identify the biomarkers involved in the molecular pathogenesis of laryngeal carcinoma. Cyclin Y (CCNY) is a conserved cell cycle regulator that acts as a growth factor in many cancers. The clinical significance of CCNY in laryngeal carcinoma remains unknown. The function of CCNY in laryngocarcinoma was studied in this paper.

Materials and Methods

CCNY knock-out cells were constructed by CRISPR/CAS9 technique. CCNY overexpression cells were also constructed based on CCNY knock-out cells. Cell growth ability was detected by MTS assay, high-content cell analysis, colony formation assays, and anchorage-independent growth assays. The protein levels in laryngocarcinoma cells were determined by Western blot. The role of CCNY in cell cycle progression was evaluated by flow cytometry.

Results

CCNY knock-out cells and CCNY up-regulation cell models were obtained successfully. Suppression of CCNY expression inhibited Hep2 cell growth. Cell growth was enhanced by the up-regulation of CCNY. The percentage of cells in G1 phase was altered when CCNY expression was down-regulated or up-regulated. The phosphorylation level of MEK and ERK as well as cyclin E protein level was also regulated by the expression level of CCNY.

Conclusion

In laryngocarcinoma cell line Hep2 cells, cell proliferation was controlled by CCNY. The expression of CCNY was involved in the cell cycle progress of Hep2 cells. It indicated that CCNY could promote cell growth by activating MEK/ERK/cyclin E signaling pathway.

Atypical cyclins in cancer: New kids on the block?

Atypical cyclins have recently emerged as a new subfamily of cyclins characterized by common structural features and interactor pattern. Interestingly, atypical cyclins are phylogenetically close to canonical cyclins, which have well-established roles in cell cycle regulation and cancer. Therefore, although the function of atypical cyclins is still poorly characterized, it seems likely that they are involved in cancer pathogenesis as well. Here, we coupled gene expression and prognostic significance analysis to bibliographic search in order to provide new insights into the role of atypical cyclins in cancer. The information gathered suggests that atypical cyclins intervene in critical processes to sustain cancer growth and have potential to become novel prognostic markers and drug targets in cancer.

Establishing a detection method for CCNY: a potentially significant clinical investigative marker in NSCLC patients

Background

CCNY, a novel cyclin family member, plays an increasingly important role in the progression of tumor invasion and metastasis, including lung cancer. However, the clinical significance of CCNY in non-small-cell lung cancer (NSCLC) patients is unknown.

Patients and methods

We prepared CCNY monoclonal antibodies, validated specific peptides by a peptide array, and established a double-antibody sandwich ELISA detection method. Then, we measured CCNY levels in 100 NSCLC patients and 50 healthy controls. A blinded validation was subsequently performed in 399 NSCLC patients and 150 healthy controls.

Results

We successfully prepared two specific mouse anti-human CCNY monoclonal antibodies and established a reliable and stable detection method. In the training set, serum CCNY was markedly increased in the NSCLC patients (P<0.05) with an integrated area under the curve of 0.751. With further analysis of the CCNY levels, there were no differences in age, sex, smoking status, tumor location, histologic subtype, or tumor size, but differences were observed in lymphatic (P<0.001) and distant (P<0.001) metastases in NSCLC patients. The CCNY[+] patients had a shorter survival time and progression-free survival than CCNY[−] patients at 3-year follow-up (P<0.001). The results were confirmed by the validation set.

Conclusion

Our study suggests that CCNY may be useful as a latent tumor marker to facilitate diagnosis and may be an effective indicator of tumor aggressiveness, playing an important role in the prognosis of NSCLC patients.

New frontiers in oncolytic viruses: optimizing and selecting for virus strains with improved efficacy

Oncolytic viruses have demonstrated selective replication and killing of tumor cells. Different types of oncolytic viruses – adenoviruses, alphaviruses, herpes simplex viruses, Newcastle disease viruses, rhabdoviruses, Coxsackie viruses, and vaccinia viruses – have been applied as either naturally occurring or engineered vectors. Numerous studies in animal-tumor models have demonstrated substantial tumor regression and prolonged survival rates. Moreover, clinical trials have confirmed good safety profiles and therapeutic efficacy for oncolytic viruses. Most encouragingly, the first cancer gene-therapy drug – Gendicine, based on oncolytic adenovirus type 5 – was approved in China. Likewise, a second-generation oncolytic herpes simplex virus-based drug for the treatment of melanoma has been registered in the US and Europe as talimogene laherparepvec.

Latest trends in cancer therapy applying viral vectors

Gene therapy based on viral vectors has demonstrated steady progress recently, not only in the area of cancers. A multitude of viral vectors has been engineered for both preventive and therapeutic applications. Two main approaches comprise of viral vector-based delivery of toxic or anticancer genes or immunization with anticancer antigens. Tumor growth inhibition and tumor regression have been observed, providing improved survival rates in animal tumor models. Furthermore, vaccine-based cancer immunotherapy has demonstrated both tumor regression and protection against challenges with lethal doses of tumor cells. Several clinical trials with viral vectors have also been conducted. Additionally, viral vector-based cancer drugs have been approved. This review gives an overview of different viral vector systems and their applications in cancer gene therapy.

Structure and inhibitor specificity of the PCTAIRE-family kinase CDK16

CDK16 (also known as PCTAIRE1 or PCTK1) is an atypical member of the cyclin-dependent kinase (CDK) family that has emerged as a key regulator of neurite outgrowth, vesicle trafficking and cancer cell proliferation. CDK16 is activated through binding to cyclin Y via a phosphorylation-dependent 14-3-3 interaction and has a unique consensus substrate phosphorylation motif compared with conventional CDKs. To elucidate the structure and inhibitor-binding properties of this atypical CDK, we screened the CDK16 kinase domain against different inhibitor libraries and determined the co-structures of identified hits. We discovered that the ATP-binding pocket of CDK16 can accommodate both type I and type II kinase inhibitors. The most potent CDK16 inhibitors revealed by cell-free and cell-based assays were the multitargeted cancer drugs dabrafenib and rebastinib. An inactive DFG-out binding conformation was confirmed by the first crystal structures of CDK16 in separate complexes with the inhibitors indirubin E804 and rebastinib, respectively. The structures revealed considerable conformational plasticity, suggesting that the isolated CDK16 kinase domain was relatively unstable in the absence of a cyclin partner. The unusual structural features and chemical scaffolds identified here hold promise for the development of more selective CDK16 inhibitors and provide opportunity to better characterise the role of CDK16 and its related CDK family members in various physiological and pathological contexts.