Cyclin D3 predicts disease-free survival in breast cancer

Cyclin D1 expression in penile cancer

The main goal of the present study was to analyze the expression profile of cyclin D1 in patients with PC, and to determine possible correlations with clinical and histopathological features. A survey was conducted with 100 patients diagnosed with PC, who were treated at two reference hospitals in São Luís, Maranhão, Brazil, between 2013 and 2017. A review of clinical, epidemiological, and histopathological data was performed, Human Papillomavírus (HPV) DNA was detected using polymerase chain reaction (PCR) and cyclin D1 expression analysis was performed using immunohistochemical techniques. The data revealed that the absence of cyclin D1 expression was significantly associated with HPV-positive histological subtypes (p = 0.001), while its expression was associated with high-grade tumors (p = 0.014), histological subtype (p = 0.001), presence of sarcomatoid transformation (p = 0.04), and perineural invasion (p = 0.023). Patients with cyclin D1 expression exhibited lower disease-free survival compared to the cyclin D1-negative group, although the difference was not statistically significant. The results suggest that cyclin D1 may be a potential biomarker for PC, especially for poorer prognosis.

Characterization, modes of interactions with DNA/BSA biomolecules and anti-tumor activity of newly synthesized dinuclear platinum(II) complexes with pyridazine bridging ligand

Platinum-based drugs are widely recognized efficient anti-tumor agents, but faced with multiple undesirable effects. Here, four dinuclear platinum(II) complexes, [{Pt(1,2-pn)Cl}2(μ-pydz)]Cl2 (C1), [{Pt(ibn)Cl}2(μ-pydz)]Cl2 (C2), [{Pt(1,3-pn)Cl}2(μ-pydz)]Cl2 (C3) and [{Pt(1,3-pnd)Cl}2(μ-pydz)]Cl2 (C4), were designed (pydz is pyridazine, 1,2-pn is ( ±)-1,2-propylenediamine, ibn is 1,2-diamino-2-methylpropane, 1,3-pn is 1,3-propylenediamine, and 1,3-pnd is 1,3-pentanediamine). Interactions and binding ability of C1-C4 complexes with calf thymus DNA (CT-DNA) has been monitored by viscosity measurements, UV-Vis, fluorescence emission spectroscopy and molecular docking. Binding affinities of C1-C4 complexes to the bovine serum albumin (BSA) has been monitored by fluorescence emission spectroscopy. The tested complexes exhibit variable cytotoxicity toward different mouse and human tumor cell lines. C2 shows the most potent cytotoxicity, especially against mouse (4T1) and human (MDA-MD468) breast cancer cells in the dose- and time-dependent manner. C2 induces 4T1 and MDA-MD468 cells apoptosis, further documented by the accumulation of cells at sub-G1 phase of cell cycle and increase of executive caspase 3 and caspase 9 levels in 4T1 cells. C2 exhibits anti-proliferative effect through the reduction of cyclin D3 and cyclin E expression and elevation of inhibitor p27 level. Also, C2 downregulates c-Myc and phosphorylated AKT, oncogenes involved in the control of tumor cell proliferation and death. In order to measure the amount of platinum(II) complexes taken up by the cells, the cellular platinum content were quantified. However, C2 failed to inhibit mouse breast cancer growth in vivo. Chemical modifications of tested platinum(II) complexes might be a valuable approach for the improvement of their anti-tumor activity, especially effects in vivo.

BRD4 PROTAC degrader MZ1 exhibits anti-B-cell acute lymphoblastic leukemia effects via targeting CCND3

INTRODUCTION

B-cell acute lymphoblastic leukemia (B-ALL) is the most prevalent malignant tumor affecting children. While the majority of B-ALL patients (90%) experience successful recovery, early relapse cases of B-ALL continue to exhibit high mortality rates. MZ1, a novel inhibitor of Bromodomains and extra-terminal (BET) proteins, has demonstrated potent antitumor activity against hematological malignancies. The objective of this study was to examine the role and therapeutic potential of MZ1 in the treatment of B-ALL.

METHODS

In order to ascertain the fundamental mechanism of MZ1, a sequence of in vitro assays was conducted on B-ALL cell lines, encompassing Cell Counting Kit 8 (CCK8) assay, Propidium iodide (PI) staining, and Annexin V/PI staining. Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) were employed to examine protein and mRNA expression levels. Transcriptomic RNA sequencing (RNA-seq) was utilized to screen the target genes of MZ1, and lentiviral transfection was employed to establish stably-expressing/knockdown cell lines.

RESULTS

MZ1 has been observed to induce the degradation of Bromodomain Containing 4 (BRD4), Bromodomain Containing 3 (BRD3), and Bromodomain Containing 2 (BRD2) in B-ALL cell strains, leading to inhibited cell growth and induction of cell apoptosis and cycle arrest in vitro. These findings suggest that MZ1 exhibits cytotoxic effects on two distinct molecular subtypes of B-ALL, namely 697 (TCF3/PBX1) and RS4;11 (MLL-AF4) B-ALL cell lines. Additionally, RNA-sequencing analysis revealed that MZ1 significantly downregulated the expression of Cyclin D3 (CCND3) gene in B-ALL cell lines, which in turn promoted cell apoptosis, blocked cell cycle, and caused cell proliferation inhibition.

CONCLUSION

Our results suggest that MZ1 has potential anti-B-ALL effects and might be a novel therapeutic target.

Targeting diacylglycerol kinase α impairs lung tumorigenesis by inhibiting cyclin D3

BACKGROUND

Diacylglycerol kinase α (DGKA) is the first member discovered from the diacylglycerol kinase family, and it has been linked to the progression of various types of tumors. However, it is unclear whether DGKA is linked to the development of lung cancer.

METHODS

We investigated the levels of DGKA in the lung cancer tissues. Cell growth assay, colony formation assay and EdU assay were used to examine the effects of DGKA-targeted siRNAs/shRNAs/drugs on the proliferation of lung cancer cells in vitro. Xenograft mouse model was used to investigate the role of DGKA inhibitor ritanserin on the proliferation of lung cancer cells in vivo. The downstream target of DGKA in lung tumorigenesis was identified by RNA sequencing.

RESULTS

DGKA is upregulated in the lung cancer cells. Functional assays and xenograft mouse model indicated that the proliferation ability of lung cancer cells was impaired after inhibiting DGKA. And cyclin D3(CCND3) is the downstream target of DGKA promoting lung cancer.

CONCLUSIONS

Our study demonstrated that DGKA promotes lung tumorigenesis by regulating the CCND3 expression and hence it can be considered as a potential molecular biomarker to evaluate the prognosis of lung cancer patients. What's more, we also demonstrated the efficacy of ritanserin as a promising new medication for treating lung cancer.

Fatty Acid Binding Protein 6 Inhibition Decreases Cell Cycle Progression, Migration and Autophagy in Bladder Cancers

Bladder cancer (BC) has a high recurrence rate worldwide. The aim of this study was to evaluate the role of fatty acid binding protein 6 (FABP6) in proliferation and migration in human bladder cancer cells. Cell growth was confirmed by MTT and colony formation assay. Western blotting was used to explore protein expressions. Wound healing and Transwell assays were performed to evaluate the migration ability. A xenograft animal model with subcutaneous implantation of BC cells was generated to confirm the tumor progression. Knockdown of FABP6 reduced cell growth in low-grade TSGH-8301 and high-grade T24 cells. Cell cycle blockade was observed with the decrease of CDK2, CDK4, and Ki67 levels in FABP6-knockdown BC cells. Interestingly, knockdown of FBAP6 led to downregulation of autophagic markers and activation of AKT-mTOR signaling. The application of PI3K/AKT inhibitor decreased cell viability mediated by FABP6-knockdown additionally. Moreover, FABP6-knockdown reduced peroxisome proliferator-activated receptor γ and retinoid X receptor α levels but increased p-p65 expression. Knockdown of FABP6 also inhibited BC cell motility with focal adhesive complex reduction. Finally, shFABP6 combined with cisplatin suppressed tumor growth in vivo. These results provide evidence that FABP6 may be a potential target in BC cells progression.

Keratin 19 interacts with GSK3β to regulate its nuclear accumulation and degradation of cyclin D3

Cyclin D3 regulates the G1/S transition and is frequently overexpressed in several cancer types including breast cancer, where it promotes tumor progression. Here we show that a cytoskeletal protein keratin 19 (K19) physically interacts with a serine/threonine kinase GSK3β and prevents GSK3β-dependent degradation of cyclin D3. The absence of K19 allowed active GSK3β to accumulate in the nucleus and degrade cyclin D3. Specifically, the head (H) domain of K19 was required to sustain inhibitory phosphorylation of GSK3β Ser9, prevent nuclear accumulation of GSK3β, and maintain cyclin D3 levels and cell proliferation. K19 was found to interact with GSK3β and K19–GSK3β interaction was mapped out to require Ser10 and Ser35 residues on the H domain of K19. Unlike wildtype K19, S10A and S35A mutants failed to maintain total and nuclear cyclin D3 levels and induce cell proliferation. Finally, we show that the K19–GSK3β-cyclin D3 pathway affected sensitivity of cells toward inhibitors to cyclin-dependent kinase 4 and 6 (CDK4/6). Overall, these findings establish a role for K19 in the regulation of GSK3β-cyclin D3 pathway and demonstrate a potential strategy for overcoming resistance to CDK4/6 inhibitors.

Transcriptomic Properties of HER2+ Ductal Carcinoma In Situ of the Breast Associate with Absence of Immune Cells

The identification of transcriptomic alterations of HER2+ ductal carcinoma in situ (DCIS) that are associated with the density of tumor-infiltrating lymphocytes (TILs) could contribute to optimizing choices regarding the potential benefit of immune therapy. We compared the gene expression profile of TIL-poor HER2+ DCIS to that of TIL-rich HER2+ DCIS. Tumor cells from 11 TIL-rich and 12 TIL-poor DCIS cases were micro-dissected for RNA isolation. The Ion AmpliSeq Transcriptome Human Gene Expression Kit was used for RNA sequencing. After normalization, a Mann-Whitney rank sum test was used to analyze differentially expressed genes between TIL-poor and TIL-rich HER2+ DCIS. Whole tissue sections were immunostained for validation of protein expression. We identified a 29-gene expression profile that differentiated TIL-rich from TIL-poor HER2+ DCIS. These genes included CCND3, DUSP10 and RAP1GAP, which were previously described in breast cancer and cancer immunity and were more highly expressed in TIL-rich DCIS. Using immunohistochemistry, we found lower protein expression in TIL-rich DCIS. This suggests regulation of protein expression at the posttranslational level. We identified a gene expression profile of HER2+ DCIS cells that was associated with the density of TILs. This classifier may guide towards more rationalized choices regarding immune-mediated therapy in HER2+ DCIS, such as targeted vaccine therapy.

DRIM: A Web-Based System for Investigating Drug Response at the Molecular Level by Condition-Specific Multi-Omics Data Integration

Pharmacogenomics is the study of how genes affect a person's response to drugs. Thus, understanding the effect of drug at the molecular level can be helpful in both drug discovery and personalized medicine. Over the years, transcriptome data upon drug treatment has been collected and several databases compiled before drug treatment cancer cell multi-omics data with drug sensitivity (IC 50, AUC) or time-series transcriptomic data after drug treatment. However, analyzing transcriptome data upon drug treatment is challenging since more than 20,000 genes interact in complex ways. In addition, due to the difficulty of both time-series analysis and multi-omics integration, current methods can hardly perform analysis of databases with different data characteristics. One effective way is to interpret transcriptome data in terms of well-characterized biological pathways. Another way is to leverage state-of-the-art methods for multi-omics data integration. In this paper, we developed Drug Response analysis Integrating Multi-omics and time-series data (DRIM), an integrative multi-omics and time-series data analysis framework that identifies perturbed sub-pathways and regulation mechanisms upon drug treatment. The system takes drug name and cell line identification numbers or user's drug control/treat time-series gene expression data as input. Then, analysis of multi-omics data upon drug treatment is performed in two perspectives. For the multi-omics perspective analysis, IC 50-related multi-omics potential mediator genes are determined by embedding multi-omics data to gene-centric vector space using a tensor decomposition method and an autoencoder deep learning model. Then, perturbed pathway analysis of potential mediator genes is performed. For the time-series perspective analysis, time-varying perturbed sub-pathways upon drug treatment are constructed. Additionally, a network involving transcription factors (TFs), multi-omics potential mediator genes, and perturbed sub-pathways is constructed, and paths to perturbed pathways from TFs are determined by an influence maximization method. To demonstrate the utility of our system, we provide analysis results of sub-pathway regulatory mechanisms in breast cancer cell lines of different drug sensitivity. DRIM is available at: http://biohealth.snu.ac.kr/software/DRIM/.

The Zn(S-pr-thiosal)2 complex attenuates murine breast cancer growth by inducing apoptosis and G1/S cell cycle arrest

Aim: We investigated the antitumor effects of zinc(II) complex with S-propyl thiosalicylic acid [Zn(S-pr-thiosal)₂] in 4T1 murine breast cancer model. Results: The Zn(S-pr-thiosal)₂ complex reduced primary tumor growth in vivo and induced tumor cell apoptosis. The Zn(S-pr-thiosal)₂ complex disrupted the balance between pro- and antiapoptotic Bcl-2 family members in 4T1 cells and induced G1/S cell cycle arrest. The Zn(S-pr-thiosal)₂ complex increased the percentage of p16, p21 and p27 positive 4T1 cells. There was a significantly decrease in expression of STAT3 and its targets c-Myc and cyclin D3 in 4T1 cells treated with the Zn(S-pr-thiosal)₂ complex thus contributing to G1/S cell cycle arrest and/or apoptosis. Conclusion: Our data suggest that the Zn(S-pr-thiosal)₂ complex restricted tumor growth through induction of mitochondrial-driven apoptosis and suppression of cell cycle progression.

The functions and targets of miR-212 as a potential biomarker of cancer diagnosis and therapy

Cancer is a major health problem worldwide. An increasing number of researchers are studying the diagnosis, therapy and mechanisms underlying the development and progression of cancer. The study of noncoding RNA has attracted a lot of attention in recent years. It was found that frequent alterations of miRNA expression not only have various functions in cancer but also that miRNAs can act as clinical markers of diagnosis, stage and progression of cancer. MiR-212 is an important example of miRNAs involved in cancer. According to recent studies, miR-212 may serve as an oncogene or tumour suppressor by influencing different targets or pathways during the oncogenesis and the development and metastasis of cancer. Its deregulation may serve as a marker for the diagnosis or prognosis of cancer. In addition, it was recently reported that miR-212 was related to the sensitivity or resistance of cancer cells to chemotherapy or radiotherapy. Here, we summarize the current understanding of miR-212 functions in cancer by describing the relevant signalling pathways and targets. The role of miR-212 as a biomarker and its therapeutic potential in cancer is also described. The aim of this review was to identify new methods for the diagnosis and treatment of human cancers.

Keratin 19 regulates cell cycle pathway and sensitivity of breast cancer cells to CDK inhibitors

Keratin 19 (K19) belongs to the keratin family of proteins, which maintains structural integrity of epithelia. In cancer, K19 is highly expressed in several types where it serves as a diagnostic marker. Despite the positive correlation between higher expression of K19 in tumor and worse patient survival, the role of K19 in breast cancer remains unclear. Therefore, we ablated K19 expression in MCF7 breast cancer cells and found that K19 was required for cell proliferation. Transcriptome analyses of KRT19 knockout cells identified defects in cell cycle progression and levels of target genes of E2F1, a key transcriptional factor for the transition into S phase. Furthermore, proper levels of cyclin dependent kinases (CDKs) and cyclins, including D-type cyclins critical for E2F1 activation, were dependent on K19 expression, and K19-cyclin D co-expression was observed in human breast cancer tissues. Importantly, K19 interacts with cyclin D3, and a loss of K19 resulted in decreased protein stability of cyclin D3 and sensitivity of cells towards CDK inhibitor-induced cell death. Overall, these findings reveal a novel function of K19 in the regulation of cell cycle program and suggest that K19 may be used to predict the efficacy of CDK inhibitors for treatments of breast cancer.

Prognostic significance of cyclin D3 expression in malignancy patients: a meta-analysis

Background

As a pivotal regulator, cyclin D3 gives play to a crucial value in conversion from the G1 stage to the S stage of cell cycle, which is implicated in tumor progression, especially proliferation and migration. Recent literatures have reported that cyclin D3 could predict survival time of malignancy patients. But, its prognostic role of cyclin D3 in neoplasms remains controversial.

Methods

Databases involving EMBASE, PubMed and Web of Science were carefully searched, and literatures investigating the prognostic effect of aberrantly expressing cyclin D3 among human cancers were collected for further analysis. We used both hazards ratios and its corresponding 95% confidence intervals to evaluate the connection among the survival rate of malignancy patients and the expression of cyclin D3.

Results

There were 13 eligible researches involving 16 cohorts and 2395 participants which were included in this study. The outcomes suggested that highly expressing cyclin D3 was significantly correlated with worse clinical prognosis of overall survival (HR 1.88; 95% CI 1.31–2.69) and disease specific survival (HR 2.68; 95% CI 1.35–5.31). But there existed no significant connection between the elevated expression of cyclin D3 with disease free survival (HR 2.65; 95% CI 0.83–8.46), recurrence-free survival (HR 2.86; 95% CI 0.82–9.96) and progression-free survival (HR 5.24; 95% CI 0.46–60.25) of diffident kinds of malignancy patients. Moreover, we discovered that elevated cyclin D3 expression was significantly connected with decreased overall survival in lymphoma (HR 3.72; 95% CI 2.18–6.36) while no significant relevance between highly expressing cyclin D3 and the overall survival in breast cancer was obtained (HR 2.12; 95% CI 0.76–5.91).

Conclusions

This meta-analysis demonstrated that highly expressing cyclin D3 might be an unfavorable prognostic biomarker for various malignancy patients, which can make great contributions to the clinical diagnosis and treatment.

Prognostic role of cyclin D2/D3 in multiple human malignant neoplasms: A systematic review and meta-analysis

Cyclin D2/D3 (CCND2/3) are core components of the machinery that drives cell cycle progression and therefore, are associated with tumorigenesis. Currently, there are contradictory evidences on the function of CCND2/3 in tumorigenesis. Thus, we conducted a comprehensive meta‐analysis to derive a precise predictive value of CCND2/3 in various tumors. We searched PubMed, EMBASE, Web of Science for eligible studies up to October 8, 2018. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) of OS or DFS/PFS/RFS were calculated using Forest plot analysis to demonstrate their associations. A total of 14 studies were ultimately included in this meta‐analysis. Our results indicated CCND2/3 played an oncogenic role in all of the cancer patients (CCND2: pooled HR = 2.21, 95% CI: 1.67‐2.93; CCND3: pooled HR = 2.29, 95% CI: 1.05‐5.03). In tumor subgroup, CCND2 was associated with shorter OS in patients with gastric cancer (HR = 2.20, 95% CI: 1.66‐2.92), whereas it might be a tumor suppressor in NSCLC (HR = 0.28, 95% CI: 0.12‐0.64). In addition, CCND3 was correlated to reduced OS in breast cancer patients (HR = 1.64, 95% CI: 1.07‐2.52) and shorter DFS/PFS/RFS in bladder cancer patients (HR = 4.60, 95% CI: 1.89‐12.57). Taken together, CCND2/3 could be the promising biomarkers for predicting the prognosis of patients with malignant neoplasms.

The organic ester O,O'-diethyl-(S,S)-ethylenediamine-N,N'-di-2-(3-cyclohexyl)propanoate dihydrochloride attenuates murine breast cancer growth and metastasis

Pharmacological treatment of cancer is mostly limited by drug-toxicity and resistance. It has been noticed that new organic ester ligand, O,O’-diethyl-(S,S)-ethylenediamine-N,N’-di-2-(3-cyclohexyl)propanoate dihydrochloride (named DE-EDCP) showed effective cytotoxic capacities against several human and mouse cancer cell lines. However, its effects on tumor growth and metastasis are unexplored. The aim of present study was to examine the ability of DE-EDCP to inhibit 4T1 murine breast cancer growth and progression and to explore possible molecular mechanisms. DE-EDCP exhibited significant tumoricidal activity on human and murine breast cancer cell lines. Further, marked reduction of murine breast cancer growth and progression by DE-EDCP was shown. DE-EDCP exhibits fewer side-effects compared to cisplatin as a conventional chemotherapeutic. Results obtained from in vivo and in vitro experiments indicate that DE-EDCP induces apoptosis and inhibits proliferation of 4T1 cells. DE-EDCP increases percentage of 4T1 cells in late apoptosis, expression of pro-apoptotic Bax and caspase-3, while decreases expression of anti-apoptotic Bcl-2. DE-EDCP treatment increased the percentage of TUNEL-positive nuclei and reduced Ki-67 expression in breast cancer tissue. DE-EDCP decreased expression of cyclin D3 and Ki-67, increased expression of cyclin-dependent kinase inhibitors p16, p21 and p27 and arrested 4T1 cells in G0/G1 cell cycle phase. Expression of STAT3 and downstream regulated molecules, NANOG and SOX2, was reduced in 4T1 cells after DE-EDCP treatment.

In conclusion, DE-EDCP impairs breast cancer growth and progression by triggering cancer cell death and inhibition of cancer cell proliferation. DE-EDCP might be of interest in the development of the new anticancer agent.

Widespread alternative exon usage in clinically distinct subtypes of Invasive Ductal Carcinoma

Cancer cells can have different patterns of exon usage of individual genes when compared to normal tissue, suggesting that alternative splicing may play a role in shaping the tumor phenotype. The discovery and identification of gene variants has increased dramatically with the introduction of RNA-sequencing technology, which enables whole transcriptome analysis of known, as well as novel isoforms. Here we report alternative splicing and transcriptional events among subtypes of invasive ductal carcinoma in The Cancer Genome Atlas (TCGA) Breast Invasive Carcinoma (BRCA) cohort. Alternative exon usage was widespread, and although common events were shared among three subtypes, ER+ HER2−, ER− HER2−, and HER2+, many events on the exon level were subtype specific. Additional RNA-seq analysis was carried out in an independent cohort of 43 ER+ HER2− and ER− HER2− primary breast tumors, confirming many of the exon events identified in the TCGA cohort. Alternative splicing and transcriptional events detected in five genes, MYO6, EPB41L1, TPD52, IQCG, and ACOX2 were validated by qRT-PCR in a third cohort of 40 ER+ HER2− and ER− HER2− patients, showing that these events were truly subtype specific.

High expression of CREPT promotes tumor growth and is correlated with poor prognosis in colorectal cancer

CREPT (cell cycle-related and expression elevated protein in tumor) is highly expressed in many kinds of cancer, and has been shown to be prognostic in certain cancers. However, the clinical significance of CREPT in colorectal cancer (CRC) has not been sufficiently investigated. In this study, we examined the CREPT expression in 225 clinical CRC tissues and paired adjacent normal tissues, and analyzed the correlation between CREPT expression and other clinicopathological features. We also evaluated the biological function of CREPT both in vitro and in vivo using knockdown or overexpressing CRC cells. Our results showed that CREPT expressed in 175 of 225 (77.8%) CRC patients and the CREPT expression was significantly associated with tumor differentiation (P = 0.000), Dukes' stages (P = 0.013) and metastasis (P = 0.038). Patients with high CREPT expression tended to have shorter survival time. Multivariate analysis showed that positive CREPT expression can be used as an independent predictor for CRC prognosis. CREPT knockdown cells showed inhibited cell proliferation and arrested cell cycle, while CREPT overexpressing cells showed increased proliferation and promoted cell cycle. In addition, CREPT overexpression significantly promoted tumor growth in vivo. Mechanism study showed that CREPT may regulate cell proliferation and cell cycle through the regulation on cyclin D3, CDK4 and CDK6.

Cortactin promotes cell migration and invasion through upregulation of the dedicator of cytokinesis 1 expression in human colorectal cancer

Cortactin (CTTN), a major substrate of the Src tyrosine kinase, has been implicated in cell proliferation, motility and invasion in various types of cancer. However, the molecular mechanisms of CTTN-driven malignant behavior remain unclear. In the current study, we determined the expression of CTTN in colorectal cancer and investigated its underlying mechanism in the metastasis of colorectal cancer. We confirmed increased CTTN expression in lymph node-positive CRC specimens and highly invasive CRC cell lines. Further study has shown that overexpression of CTTN promoted CRC cell migration and invasion, whereas CTTN silencing inhibited CRC cell migratory and invasive capacities in vitro. Mechanistically, CTTN increases expression of dedicator of cytokinesis 1 (DOCK1) and gene silencing of DOCK1 partially abolishes the migration and invasion capacity by CTTN. Our findings indicate that CTTN promotes metastasis of CRC cells by increasing DOCK1 expression and this could offer a promising therapeutic target for colorectal cancer treatment.

Restoration of microRNA-212 causes a G0/G1 cell cycle arrest and apoptosis in adult T-cell leukemia/lymphoma cells by repressing CCND3 expression

Adult T-cell leukemia/lymphoma (ATL) is a highly aggressive T-cell malignancy. This study was designed to explore the expression and functional significance of microRNA (miR)-212 in ATL. The expression of miR-212 in human ATL tissues and cell lines were investigated. Gain-of-function experiments were carried out to determine the roles of miR-212 in cell proliferation, tumorigenesis, cell cycle progression, and apoptosis. We also identified and functionally characterized the target genes of miR-212 in ATL cells. Compared with normal lymph node biopsies, lymphoma samples from ATL patients displayed underexpression of miR-212 (p=0.0032). Consistently, miR-212 was downregulated in human ATL cell lines, compared with normal T lymphocytes. Restoration of miR-212 significantly (p<0.05) inhibited ATL cell proliferation and tumorigenesis in mice. Overexpression of miR-212 led to an accumulation of G0/G1-phase cells and a concomitant reduction of S-phase cells. Moreover, enforced expression of miR-212-induced significant apoptosis in ATL cells. CCND3, which encodes a cell cycle regulator cyclin D3, was identified as a direct target of miR-212 in ATL cells. Rescue experiments with a miR-212-resistant variant of CCND3 demonstrated that overexpression of CCND3 restored cell-cycle progression and attenuated apoptotic response in miR-212-overexpressing ATL cells. Taken together, miR-212 exerts growth-suppressive effects in ATL cells largely by targeting CCND3 and may have therapeutic potential in ATL.