D-type Cyclins are important downstream effectors of cytokine signaling that regulate the proliferation of normal and neoplastic mammary epithelial cells

Impaired cyclin D3 protein degradation contributes to trastuzumab resistance in HER2 positive breast cancer

As the first anti-HER2 targeted agent approved by FDA in 1998, Trastuzumab has significantly improved the outcome of patients with HER2 positive metastatic breast cancer. Unfortunately, resistance to trastuzumab is a severe obstacle to its therapeutic efficacy in clinical application, and its mechanism has not yet been fully elucidated. In our study, we found that stabilization of cyclin D3 could be one reason for trastuzumab resistance. Trastuzumab could induce G1/G0 phase arrest by downregulating cyclin D3 protein expression. However, the protein expression of cyclin D3 was not affected in trastuzumab-resistant cells, which might be related to aberrant activation of ERK signaling pathway. Furthermore, degradation of cyclin D3 protein by trastuzumab was mainly resulted from ubiquitin-dependent proteasome mechanism instead of transcriptional regulation. In trastuzumab-resistant breast cancer cells, trastuzumab-induced degradation of cyclin D3 protein was abrogated. When the ubiquitin pathway was inhibited, cells would show a predisposition to resistance to trastuzumab. Further, CDK4/6 inhibitor can inhibit the proliferation of trastuzumab-resistant HER-2 positive breast cancer cells. Therefore, combination of CDK4/6 inhibitors and anti-HER2 targeted therapy may be an alternative and promising strategy to overcome trastuzumab resistance in the future.

De novo synthesis of monounsaturated fatty acids modulates exosome-mediated lipid export from human granulosa cells

BACKGROUND

Ovarian somatic cells support the maturation and fertility of oocytes. Metabolic desaturation of fatty acids in these cells has a positive paracrine impact on the maturation of oocytes. We hypothesized that the enzyme stearoyl-CoA desaturase 1 (SCD1) in granulosa cells regulates the lipid cargo of exosomes secreted from these cells by maintaining the balance between saturated and unsaturated lipids. We investigated the effect of SCD1 on exosome lipid content in a cumulus-granulosa cell model under physiologically relevant in vitro conditions.

METHODS

Non-luteinized human COV434 granulosa cells were subjected to treatment with an inhibitor of SCD1 (SCDinhib) alone, in combination with oleic acid, or under control conditions. Subsequently, the exosomes were isolated and characterized via nanoparticle tracking analysis, transmission electron microscopy, and Western blotting. We used liquid chromatography mass spectrometry to investigate the lipidomic profiles. We used quantitative PCR with TaqMan primers to assess the expression of genes involved in lipogenesis and control of cell cycle progression.

RESULTS

A trend toward exosome production was observed with a shift toward smaller exosome sizes in cells treated with SCD1inhib. This trend reached statistical significance when SCDinhib was combined with oleic acid supplementation. SCD1 inhibition led to the accumulation of saturated omega-6 lipids in exosomes. The latter effect was reversed by oleic acid supplementation, which also improved exosome production and suppressed the expression of fatty acid synthase and Cyclin D2.

CONCLUSION

These findings underscore the critical role of de novo fatty acid desaturation in the regulation of the export of specific lipids through exosomes, with potential implications for controlling intercellular communication within the ovary.

CCND2 is a prognostic biomarker and correlates with immune infiltration in lung adenocarcinoma

Background

CCND2 expression influences the growth and proliferation of cancer cells and plays a crucial role in immune response of tumor. However, few studies focused on the correlation between CCND2 and lung adenocarcinoma (LUAD) in terms of prognosis and tumor immune infiltration.

Methods

Original LUAD case data were screened from The Cancer Genome Atlas (TCGA) database. Using R software, we analyzed differently expressed CCND2 between LUAD and adjacent normal tissues. Kaplan-Meier analysis was conducted to determine the relationship between CCND2 expression and the overall survival of LUAD patients, and Cox regression analysis was performed to identify the independently prognostic risk factors for LUAD. Using TIMER (Tumor Immune Estimation Resource) and CIBERSORTx (Cell-type Identification by Estimating Relative Subsets of known RNA Transcripts) databases, the connection between CCND2 expression and LUAD immune infiltration was investigated.

Results

The level of CCND2 was significantly lower in LUAD than in adjacent normal tissues [adjusted P<0.05 and log2 fold change (FC) =-1.33]. LUAD patients who expressed lower CCND2 had a shorter overall survival (P=0.046) and CCND2 was an independently prognostic risk factor for LUAD [hazard ratio (HR): 0.77, P=0.049]. In LUAD patients, CCND2 expression was positively associated with the levels of B cells (r=0.159, P=4.00e-04), CD8+ T cells (r=0.287, P=7.88e-11), CD4+ T cells (r=0.301, P=8.14e-12), macrophages (r=0.128, P=4.57e-03), neutrophils (r=0.373, P=1.07e-17), and myeloid dendritic cells (r=0.284, P=1.43e-10). The levels of B cells and macrophages had significantly association with the overall survival of LUAD patients. CIBERSORTx showed that the proportions of naive B cells, resting dendritic cells, and macrophages M1 were higher in the low CCND2 expression group (P<0.05); whereas macrophages M1, activated natural killer (NK) cells, and resting CD4+ memory cells were lower (P<0.05).

Conclusions

CCND2 can be exploited as a novel prognostic biomarker involved in immune infiltration of LUAD, hence providing new preventative and therapeutic options for LUAD.

The Role of Cyclin-Dependent Kinases (CDK) 4/6 in the Ovarian Tissue and the Possible Effects of Their Exogenous Inhibition

The combination of cyclin-dependent kinase (CDK) 4/6 inhibitors with endocrine therapy is the standard treatment for patients with HR+/HER2- advanced breast cancer. Recently, this combination has also entered the early setting as an adjuvant treatment in patients with HR+/HER2- disease at a high risk of disease recurrence following (neo)adjuvant chemotherapy. Despite their current use in clinical practice, limited data on the potential gonadotoxicity of CDK4/6 inhibitors are available. Hence, fully informed treatment decision making by premenopausal patients concerned about the potential development of premature ovarian insufficiency and infertility with the proposed therapy remains difficult. The cell cycle progression of granulosa and cumulus cells is a critical process for ovarian function, especially for ensuring proper follicular growth and acquiring competence. Due to the pharmacological properties of CDK4/6 inhibitors, there could be a potentially negative impact on ovarian function and fertility in women of reproductive age. This review aims to summarize the role of the cyclin D-CDK4 and CDK6 complexes in the ovary and the potential impact of CDK4/6 inhibition on its physiological processes.

Inhibition of USP10 induces myeloma cell apoptosis by promoting cyclin D3 degradation

The cell cycle regulator cyclin D3 (CCND3) is highly expressed in multiple myeloma (MM) and it promotes MM cell proliferation. After a certain phase of cell cycle, CCND3 is rapidly degraded, which is essential for the strict control of MM cell cycle progress and proliferation. In the present study, we investigated the molecular mechanisms regulating CCND3 degradation in MM cells. By utilizing affinity purification-coupled tandem mass spectrometry, we identified the deubiquitinase USP10 interacting with CCND3 in human MM OPM2 and KMS11 cell lines. Furthermore, USP10 specifically prevented CCND3 from K48-linked polyubiquitination and proteasomal degradation, therefore enhancing its activity. We demonstrated that the N-terminal domain (aa. 1-205) of USP10 was dispensable for binding to and deubiquitinating CCND3. Although Thr283 was important for CCND3 activity, it was dispensable for CCND3 ubiquitination and stability modulated by USP10. By stabilizing CCND3, USP10 activated the CCND3/CDK4/6 signaling pathway, phosphorylated Rb, and upregulated CDK4, CDK6 and E2F-1 in OPM2 and KMS11 cells. Consistent with these findings, inhibition of USP10 by Spautin-1 resulted in accumulation of CCND3 with K48-linked polyubiquitination and degradation that synergized with Palbociclib, a CDK4/6 inhibitor, to induce MM cell apoptosis. In nude mice bearing myeloma xenografts with OPM2 and KMS11 cells, combined administration of Spautin-l and Palbociclib almost suppressed tumor growth within 30 days. This study thus identifies USP10 as the first deubiquitinase of CCND3 and also finds that targeting the USP10/CCND3/CDK4/6 axis may be a novel modality for the treatment of myeloma.

Analysis of circRNA and miRNA expression profiles in IGF3-induced ovarian maturation in spotted scat (Scatophagus argus)

Insulin-like growth factor 3 (IGF3) induces ovarian maturation in teleosts; however, research on its molecular regulatory mechanism remains deficient. Circular RNAs (circRNAs) and microRNAs (miRNAs) are involved in various biological processes, including reproduction. In this study, circRNAs and miRNAs involved in IGF3-induced ovarian maturation were evaluated in spotted scat (Scatophagus argus). In ovarian tissues, we identified 176 differentially expressed (DE) circRNAs and 52 DE miRNAs between IGF3 treatment and control groups. Gene Ontology (GO) enrichment analyses showed that host genes of DE circRNAs and target genes of DE miRNAs were enriched for various processes with a high degree of overlap, including cellular process, reproduction, reproductive process, biological adhesion, growth, extracellular region, cell junction, catalytic activity, and transcription factor activity. Enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways included cell adhesion molecules, ECM-receptor interaction, regulation of actin cytoskeleton, focal adhesion, cell cycle, Hedgehog signaling pathway, phosphatidylinositol signaling system, PI3K-Akt signaling pathway, Apelin signaling pathway, Notch signaling pathway, insulin signaling pathway, and Rap1 signaling pathway. A circRNA-miRNA-mRNA regulatory network was constructed, including DE genes involved in reproduction (e.g., oocyte maturation, oocyte meiosis, and ECM remodeling), such as ccnd2, hecw2, dnm2, irs1, adam12, and cdh13. According to the regulatory network and tissue distribution, we identified one circRNA (Lachesis_group5:6245955|6270787) and three miRNAs (novel_miR_622, novel_miR_980, and novel_miR_64) that may exert regulatory effects in IGF3-induced ovarian maturation in S. argus. Taken together, this study provides a novel insight into the molecular mechanisms by which IGF3 functions in ovaries and highlights the effects of circRNAs and miRNAs in reproduction in S. argus.

Lysine stimulates the development of the murine mammary gland at puberty via PI3K/AKT/mTOR signalling axis

Lysine is one of the essential amino acids. The effect of lysine on milk protein and milk fat anabolism has been reported, but the effect on mammary glands development has not been studied in detail. The normal development of the mammary glands at puberty is crucial to lactation of mammals. In this study, to explore the effect of lysine on mammary glands development, we fed different concentrations of lysine (0.025%, 0.05%, 0.1%) to pubertal mice and found that the addition of 0.1% lysine to drinking water significantly promoted mammary glands development. Furthermore, we treated mMECs (mouse mammary epithelial cells) with different concentrations of lysine (0, 0.2, 0.4, 0.6, 0.8 and 1 mM) to explore the underlying mechanism, and found that lysine promoted the proliferation of mMECs and development of mammary glands through PI3K/AKT/mTOR signalling pathway in pubertal mice. Overall, the results of this study revealed that lysine activated the PI3K/AKT/mTOR signal axis, elevated protein concentrations of cell proliferation markers, such as PCNA, Cyclin D1 and D3, and enhanced the proliferation of mMECs, finally promoted the murine mammary glands development at puberty.

Gene identification and functional analysis of a D-type cyclin (CCND2) in freshwater pearl mussel (Hyriopsis cumingii)

BACKGROUND

Cyclin D (CCND) plays an important role in the cell cycle and is a rate-limiting factor that facilitates the G1/S transition.

METHODS

In this study, the full-length cDNA of Hc-CCND2 was isolated from freshwater pearl mussel (Hyriopsis cumingii; Hc) and amplified using the 3´/5´ RACE system. The Hc-CCND2 expression profiles were analysed by quantitative real-time PCR. Functional analysis of the Hc-CCND2 genes was examined by both RNA interference (RNAi) and overexpression in H. cumingii.

RESULTS

Hc-CCND2 protein sequences were 295 amino acids long, possessed D-type cyclin signature motifs and contained conserved cyclin box domains. Hc-CCND2 was expressed in all examined tissues (adductor, foot, visceral mass, gill, outer mantle, inner mantle and gonad), with the highest expression levels found in the gill (P < 0.05). During the different developmental periods of the embryo, the relative expression of Hc-CCND2 increased with embryonic development, peaking at the blastula stage and decreasing significantly in the gastrula stage. After knockdown of Hc-CCND2 by RNAi, a significant decrease in CDK6 expression levels was found, while the percentage of cells in the G0/G1 phase significantly increased. Overexpression of Hc-CCND2 in mantle cells led to increased proliferation of cultured cells (P < 0.05).

CONCLUSIONS

Our results demonstrated that Hc-CCND2 may promote cell cycle progression in H. cumingii, and that overexpression of Hc-CCND2 promotes mantle cell proliferation. These findings may provide a novel approach for improving the slow proliferation rate of shellfish cells in in vitro cultures.

Coordinated regulation of gene expression and microRNA changes in adipose tissue and circulating extracellular vesicles in response to pioglitazone treatment in humans with type 2 diabetes

Pioglitazone, a PPARγ agonist, is used to treat type 2 diabetes (T2D). PPARγ is highly expressed in adipose tissue (AT), however the effects of pioglitazone to improve insulin sensitivity are also evident in other tissues and PPARγ agonism has been shown to alter cancer derived extracellular vesicle (EV)-miRNAs. We hypothesized that pioglitazone modifies the cargo of circulating AT-derived EVs to alter interorgan crosstalk in people with diabetes. We tested our hypothesis in a 3-month trial in which 24 subjects with T2D were randomized to treatment with either pioglitazone 45 mg/day or placebo (NCT00656864). Levels of 42 adipocyte-derived EV-miRNAs were measured in plasma EVs using low density TaqMan arrays. Levels of differentially expressed EV-miRNAs and their most relevant target genes were also measure in adipose tissue from the same participants, using individual TaqMan assays. Levels of 5 miRNAs (i.e., miR-7-5p, miR-20a-5p, miR-92a-3p, miR-195-5p, and miR-374b-5p) were significantly downregulated in EVs in response to pioglitazone treatment relative to placebo. The opposite occurred for miR-195-5p in subcutaneous AT. Changes in miRNA expression in EVs and AT correlated with changes in suppression of lipolysis and improved insulin sensitivity, among others. DICER was downregulated and exosomal miRNA sorting-related genes YBX1 and hnRNPA2B1 displayed a downregulation trend in AT. Furthermore, analysis of EV-miRNA targeted genes identified a network of transcripts that changed in a coordinated manner in AT. Collectively, our results suggest that some beneficial pharmacologic effects of pioglitazone are mediated by adipose-specific miRNA regulation and exosomal/EV trafficking.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, identifier NCT00656864.

Overexpression of miR-221 stimulates proliferation of rat neural stem cell with activating Phosphatase and tensin homolog/protein kinase B signaling pathway

Neural stem cells (NSCs) are self-renewing, multipotent cells, and remain in our brains throughout life. They could be activated by brain damage and involved in the central nervous system (CNS) repair and motor functional recovery. Previous research demonstrated that miR-221 could regulate proliferation, differentiation, and survival. However, the effect of miR-221 on NSCs remains unknown. In this study, we showed that overexpression of miR-221 inhibited the expression of phosphatase and tensin homolog (PTEN) protein and increased the phosphorylation level of protein kinase B (AKT). More importantly, an AKT-specific inhibitor abolished the effect of miR-221 on the phosphorylation level of AKT. 5-Bromo-2-deoxyUridine (BrdU) incorporation assay and Cyclin D1 expression showed that miR-221 overexpression further promoted the NSCs proliferation. However, knocking down miR-221 inhibited cell proliferation. The AKT-specific inhibitor also blocked the proliferative efficiency of miR-221. These results demonstrated that miR-221 overexpression promoted the proliferation of cultured rat NSCs, for which the PTEN/AKT pathway activation was one possible mechanism. Our research may provide a novel investigating strategy to improve stem cell treatment for CNS diseases.

Chondroprotective Effects of Combination Therapy of Acupotomy and Human Adipose Mesenchymal Stem Cells in Knee Osteoarthritis Rabbits via the GSK3β-Cyclin D1-CDK4/CDK6 Signaling Pathway

Adipose-derived stem cells (ASCs) are highly chondrogenic and can be used to treat knee osteoarthritis (KOA) by alleviating cartilage defects. Acupotomy, a biomechanical therapy guided by traditional Chinese medicine theory, alleviates cartilage degradation and is widely used in the clinic to treat KOA by correcting abnormal mechanics. However, whether combining acupotomy with ASCs will reverse cartilage degeneration by promoting chondrocyte proliferation in KOA rabbits is unknown. The present study aimed to investigate the effects of combination therapy of acupotomy and ASCs on chondrocyte proliferation and to determine the underlying mechanism in rabbits with KOA induced by knee joint immobilization for 6 weeks. After KOA modeling, five groups of rabbits (acupotomy, ASCs, acupotomy + ASCs, model and control groups) received the indicated intervention for 4 weeks. The combination therapy significantly restored the KOA-induced decrease in passive range of motion (PROM) in the knee joint and reduced the elevated serum level of cartilage oligomeric matrix protein (COMP), a marker for cartilage degeneration. Furthermore, magnetic resonance imaging (MRI) and scanning electron microscopy (SEM) images showed that the combination therapy inhibited cartilage injury. The combination therapy also significantly blocked increases in the mRNA and protein expression of glycogen synthase kinase-3β (GSK3β) and decreases in the mRNA and protein expression of cyclin D1/CDK4 and cyclin D1/CDK6 in cartilage. These findings indicated that the combination therapy mitigated knee joint immobility, promoted chondrocyte proliferation and alleviated cartilage degeneration in KOA rabbits, and these effects may be mediated by specifically regulating the GSK3β-cyclin D1-CDK4/CDK6 pathway.

RPL21 siRNA Blocks Proliferation in Pancreatic Cancer Cells by Inhibiting DNA Replication and Inducing G1 Arrest and Apoptosis

Background

Our previous study showed that the ribosomal protein L21 (RPL21) may play an important role in the development and survival of pancreatic cancer. In this article, RNA interference (RNAi) experiments were performed with RPL21-specific small interfering RNA (siRNA) to elucidate the mechanism by which RPL21 controls PC PANC-1 and BxPC-3 cell proliferation.

Methods

In the present study, PANC-1, BxPC-3 cells, and BALB/c nude mice were used to investigate antitumor effect and mechanism by which RPL21 controls cell proliferation and apoptosis in vitro and in vivo. The effects of RPL21 knockdown on PANC-1 and BxPC-3 cell proliferation, cell cycle and cell apoptosis in vitro were determined using 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assays and flow cytometry assay. The mechanism of RPL21 regulating cell proliferation was investigated using transcriptome sequencing analysis and luciferase reporter assay. The effects of RPL21 knockdown on PANC-1 and BxPC-3 cell proliferation in vivo were determined using BALB/c nude mice tumor model.

Results

In PANC-1 and BxPC-3 cells, the knockdown of RPL21 expression with corresponding siRNA suppressed cell proliferation in vitro and in vivo, inhibited DNA replication, and induced arrests in the G1 phase of the cell cycle. Further results showed that the mini-chromosome maintenance (MCM) protein family (MCM2-7), CCND1 and CCNE1 were down-regulated significantly in PANC-1 and BxPC-3 cells after transfected with RPL21 siRNA, which suggests that the suppression of DNA replication is due to the reduced expression of MCM2-7 family, and the induction of G1 arrest is correlated with the inhibition of CCND1 and CCNE1. Luciferase reporter assay showed that RPL21 controls the DNA replication and G1-S phase progression possibly through the regulation of E2F1 transcription factor in PC cells. Moreover, RPL21 siRNA showed an apoptosis-inducing effect only in BxPC-3 and PANC-1 cells but not in normal HPDE6-C7 cells. The increase of caspase-8 activities and the loss of mitochondrial membrane potential after RPL21 silencing indicates that the RPL21 gene may be involved in caspase-8-related mitochondrial apoptosis.

Conclusion

Our findings suggest that siRNA against the RPL21 gene possesses a potential anti-cancer activity for PC cells by inhibiting their proliferation and DNA replication, as well as inducing cell cycle G1 arrest and cell apoptosis.

A tetraprenylated benzophenone 7-epiclusianone induces cell cycle arrest at G1/S transition by modulating critical regulators of cell cycle in breast cancer cell lines

Breast cancer is a complex disease and encompassing different types of tumor. Although advances in understanding of the molecular bases of breast cancer biology, the therapeutic proposals available still are not effective. In this scenario, the present study aimed to evaluate the mechanisms associated to antitumor activity of 7-Epiclusianone (7-Epi), a tetraprenylated benzophenone, on luminal A (MCF-7) and claudin-low (Hs 578T) breast cancer cell lines. We found that 7-Epi efficiently inhibited cell proliferation and migration of these cells; however MCF-7 was slightly more responsive than Hs 578T. Cell cycle analysis showed accumulation of cells at G0/G1 phase with drastic reduction of S population in treated cultures. This effect was associated to downregulation of CDKN1A (p21) and cyclin E in both cell lines. In addition, 7-Epi reduced cyclin D1 and p-ERK expression levels in MCF-7 cell line. Cytotoxic effect of 7-Epi on breast cancer cell lines was associated to its ability to increase BAX/BCL-2 ratio. In conclusion, our findings showed that 7-Epi is a promising antitumor agent against breast cancer by modulating critical regulators of the cell cycle and apoptosis.

Efficient tissue-type specific expression of target genes in a tetracycline-controlled manner from the ubiquitously active Eef1a1 locus

Using an efficient gene targeting approach, we developed a novel mouse line that expresses the tetracycline-controlled transactivator (tTA) from the constitutively active Eef1a1 locus in a Cre recombinase-inducible manner. The temporally and spatially controlled expression of the EF1-LSL-tTA knockin and activation of tTA-driven responder transgenes was tested using four transgenic lines that express Cre under tissue-specific promoters of the pancreas, mammary gland and other secretory tissues, as well as an interferon-inducible promoter. In all models, the endogenous Eef1a1 promoter facilitated a cell-type-specific activation of target genes at high levels without exogenous enhancer elements. The applicability of the EF1-LSL-tTA strain for biological experiments was tested in two studies related to mammary gland development and tumorigenesis. First, we validated the crucial role of active STAT5 as a survival factor for functionally differentiated epithelial cells by expressing a hyperactive STAT5 mutant in the mammary gland during postlactational remodeling. In a second experiment, we assessed the ability of the EF1-tTA to initiate tumor formation through upregulation of mutant KRAS. The collective results show that the EF1-LSL-tTA knockin line is a versatile genetic tool that can be applied to constitutively express transgenes in specific cell types to examine their biological functions at defined developmental stages.

Cyclin D1 differential activation and its prognostic impact in patients with advanced breast cancer treated with trastuzumab

Introduction

We sought to determine the level of activation of the critical components of the cyclin D1-mediated pathway and to evaluate their prognostic significance across the different molecular subtypes of advanced breast cancer.

Patients and methods

The study population comprised 219 female patients with advanced breast cancer who had been found to have human epidermal growth factor receptor 2 (HER2)-positive disease by local testing and were all treated with trastuzumab-based regimens. For all tumours, central testing for HER2 was performed, and cyclin D1 gene (CCND1) amplification, mRNA and protein expression were assessed by FISH, quantitative real-time-PCR and immunohistochemistry, respectively. Prognostic impact on clinical endpoints was evaluated with Cox regression analyses.

Results

After central testing, only 134 (61.2%) of 219 patients were confirmed to have HER2 gene amplification by FISH and/or 3+ HER2 protein expression by immunohistochemistry. After a median follow-up time of 136.0 months (95% CI 123.3 to 148.9), 105 (78.4%) HER2-positive patients and 76 (89.4%) HER2-negative patients had died, while 80% of the former and 87.1% of the latter had experienced a disease relapse. Patients with positive oestrogen receptor/progesterone receptor status presented with higher cyclin D1 mRNA expression. In the HER2-negative subgroup, patients with negative cyclin D1 protein expression were at higher risk of progression (HR= 1.66, 95%CI 1.01 to 2.72, Wald’s p=0.045). Among de novo metastatic patients, the risk of progression was higher for patients with non-amplified CCND1 tumours (HR= 2.00, 95% CI 1.03 to 3.90, p=0.041).

Conclusion

Aberrant activation of the cyclin D1-mediated pathway appears to reduce the risk of progression in HER2-negative tumours, but not in HER2-positive ones.

miR‑145 suppresses ovarian cancer progression via modulation of cell growth and invasion by targeting CCND2 and E2F3

MicroRNAs (miRNA/miRs) have been demonstrated to be critical post‑transcriptional modulators of gene expression during tumorigenesis. Numerous miRNAs have been revealed to be downregulated in human epithelial ovarian cancer (EOC). In the present study, it was observed that the expression of miR‑145 was decreased in EOC tissues and cell lines. Overexpression of miR‑145 inhibited the proliferation, migration and invasion of EOC cells. The D‑type cyclin 2, cyclin D2 (CCND2), and E2F transcription factor 3 (E2F3) were confirmed to be targets of miR‑145. In addition, restoration of these 2 genes significantly reversed the tumor suppressive effects of miR‑145. Collectively, the results indicated that miR‑145 serves a critical role in suppressing the biological behavior of EOC cells by targeting CCND2 and E2F3. Therefore, miR‑145 was suggested to be a potential miRNA‑based therapeutic target in ovarian cancer.

An RNA Aptamer Targeting the Receptor Tyrosine Kinase PDGFRα Induces Anti-tumor Effects through STAT3 and p53 in Glioblastoma

Human glioblastoma (GBM) is the most aggressive malignancy of the CNS, with less than 5% survival. Despite great efforts to find effective therapeutics, current options remain very limited. To develop a targeted cancer therapeutic, we selected RNA aptamers against platelet-derived growth factor receptor α (PDGFRα), which is a receptor tyrosine kinase. One RNA aptamer (PDR3) with high affinity (0.25 nM) showed PDGFRα specificity and was internalized in U251-MG cells. Following treatment with the PDR3 aptamer, expression of the transcription factor STAT3 (signal transducer and activator of transcription 3) was inhibited, whereas the expression of the histone demethylase JMJD3 and the tumor suppressor p53 were upregulated. PDR3 also upregulated serine phosphorylation of p53, which subsequently mediated apoptosis through the death receptors: tumor necrosis factor (TNF)-related apoptosis-inducing ligand receptors 1/2 (TRAIL-R1/R2), Fas-associated via death domain (FADD), and Fas. PDR3 significantly decreased cell viability in a dose-dependent manner. Furthermore, translocation of PDR3 into the nucleus induced hypomethylation at the promoters of cyclin D2. To assess the feasibility of targeted delivery, we conjugated PDR3 aptamer with STAT3-siRNA for a chimera. The PDR3-siSTAT3 chimera successfully inhibited the expression of target genes and showed significant inhibition of cell viability. In summary, our results show that well-tailored RNA aptamers targeting the PDGFRα-STAT3 axis have the potential to act as anti-cancer therapeutics in GBM.

Myosin 1e promotes breast cancer malignancy by enhancing tumor cell proliferation and stimulating tumor cell de-differentiation

Despite advancing therapies, thousands of women die every year of breast cancer. Myosins, actin-dependent molecular motors, are likely to contribute to tumor formation and metastasis via their effects on cell adhesion and migration and may provide promising new targets for cancer therapies. Using the MMTV-PyMT murine model of breast cancer, we identified Myosin 1e (MYO1E) as a novel tumor promoter. Tumor latency in mice lacking MYO1E was significantly increased, and tumors formed in the absence of MYO1E displayed unusual papillary morphology, with well-differentiated layers of epithelial cells covering fibrovascular cores, rather than solid sheets of tumor cells typically observed in this cancer model. These tumors were reminiscent of papillary breast cancer in humans that is typically non-invasive and often cured by tumor excision. MYO1E-null tumors exhibited decreased expression of the markers of cell proliferation, which was recapitulated in primary tumor cells derived from MYO1E-null mice. In agreement with our findings, meta-analysis of patient survival data indicated that MYO1E expression level was associated with reduced recurrence-free survival in basal-like breast cancer. Overall, our data suggests that MYO1E contributes to breast tumor malignancy and regulates the differentiation and proliferation state of breast tumor cells.

Transcriptome profiling of whitefly guts in response to Tomato yellow leaf curl virus infection

BACKGROUND

Plant viruses in agricultural crops are of great concern worldwide, and over 75% of them are transmitted from infected to healthy plants by insect vectors. Tomato yellow leaf curl virus (TYLCV) is a begomovirus, which is the largest and most economically important group of plant viruses, transmitted by the whitefly Bemisia tabaci. The circulation of TYLCV in the insect involves complex insect-virus interactions, whereas the molecular mechanisms of these interactions remain ambiguous. The insect gut as a barrier for viral entry and dissemination is thought to regulate the vector specificity. However, due to its tiny size, information for the responses of whitefly gut to virus infection is limited.

METHODS

We investigated the transcriptional response of the gut of B. tabaci Middle East-Asia Minor 1 species to TYLCV infection using Illumina sequencing.

RESULTS

A total of 5207 differentially expressed genes (DEGs) between viruliferous and non-viruliferous whitefly guts were identified. Enrichment analyses showed that cargo receptor and ATP-binding cassette (ABC) transporters were enriched in DEGs, and might help the virus to cross gut barrier. TYLCV could perturb cell cycle and DNA repair as a possible result of its replication in the whitefly. Our data also demonstrated that TYLCV can activate whitefly defense responses, such as antimicrobial peptides. Meanwhile, a number of genes involved in intracellular signaling were activated by TYLCV infection.

CONCLUSIONS

Our results reveal the complex insect-virus relationship in whitefly gut and provide substantial molecular information for the role of insect midguts in virus transmission.

Assessment of a FBXW8 frameshift mutation, c.1312_1313delGT, in breast cancer patients and controls from Central Europe

F-box proteins participate in multiple cellular processes through ubiquitylation and subsequent degradation of target proteins, such as cyclin D1 as target of FBXW8. To investigate the spectrum of FBXW8 germ-line mutations in patients with breast cancer and healthy controls, we analyzed the whole FBXW8 coding region and flanking untranslated portions in germ-line DNA samples of 91 breast cancer patients and 277 healthy controls using next-generation amplicon sequencing. Five missense variants, one splice site variant, one frameshift variant, one synonymous variant, and one variant in the 3'-UTR were identified. Frameshift mutation FBXW8 c.1312_1313delGT was considered functionally relevant and was investigated for its potential association with breast cancer risk through subsequent genotyping in two hospital-based breast cancer case-control series from Belarus and Germany, respectively, comprising a total of 2740 breast cancer cases and 2174 controls. The mutation was found in 30 cases and 23 controls with an adjusted Odds Ratio 1.02 (95% CI 0.59-1.77; p = 0.94) in the combined analysis. There was no statistically significant difference when patients were stratified by ER status, PR status, age at diagnosis, ductal histology, contralateral status, family history or tumor grade. Altogether, our data exclude clinically actionable breast cancer risks above two-fold for the FBXW8 c.1312_1313delGT mutation, although larger studies would be needed to exclude low-penetrance associations.

Curcumol induces cell cycle arrest in colon cancer cells via reactive oxygen species and Akt/ GSK3β/cyclin D1 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Curcuma kwangsiensis S. G. Lee & C. F. Liang (Guangxi ezhu, in Chinese) belongs to the Zingiberaceae family, has been used as a traditionally Chinese medicine nearly 2000 year. Curcumol is one of the guaiane-type sesquiterpenoid hemiketal isolated from medicine plant Curcuma kwangsiensis S. G. Lee & C. F. Liang, which has been reported possesses anti-cancer effects. Our previous study found that the most contribution to inhibit nasopharyngeal carcinoma cell growth was curcumol.

AIM OF THE STUDY

To assess the effect of curcumol on cell cycle arrest against human colon cancer cells (CRC) cells (LoVo and SW480) and explore its mechanism in vitro and in vivo.

MATERIALS AND METHODS

Curcumol was dissolved in absolute ethyl alcohol. The concentration of absolute ethyl alcohol in the control group or in experimental samples was always 1/500 (v/v) of the final medium volume. LoVo and SW480 cells were treated with different concentrations of curcumol (0, 53, 106, 212 and 424μM). And then the cell cycle of each group was examined by flow cytometry. The protein levels of PI3K, p-Akt, cyclin D1, cyclin E, CDK2, CDK4 and GSK3β were determined by Western blot. The mRNA expression of PI3K, Akt, cyclin D1, CDK4, P27, p21, and P16 in the treated cells were analyzed by real-time RT-PCR. In addition, the antitumor activity of curcumol was evaluated in nude mice bearing orthotopic tumor implants.

RESULTS

Curcumol induced cell cycle arrest in G1/S phase. RT-qPCR and Western blot data showed that curcumol enhanced the expression of GSK3β, P27, p21 and P16, and decreased the levels of PI3K, phosphorylated Akt (p-Akt), cyclin D1, CDK4, cyclin E and CDK2. Furthermore, curcumol induced reactive oxygen species (ROS) generation in LoVo cells, and ROS scavenger N-acetylcysteine (NAC) significantly reversed curcumol-induced cell growth inhibition. Besides, curcumol also prevented the growth of human colon cancer cells xenografts in nude mouse, accompanied by the reduction of PI3K, Akt, cyclin D1, CDK4, cycln E and significant increase of GSK3β.

CONCLUSIONS

Curcumol caused cell cycle arrest at the G0/G1 phase by ROS production and Akt/ GSK3β/cyclin D1 pathways inactivation, indicating the potential of curcumol in the prevention of colon cancer carcinogenesis.

Protein expression patterns of cell cycle regulators in operable breast cancer

Background-Aim

To evaluate the prognostic role of elaborate molecular clusters encompassing cyclin D1, cyclin E1, p21, p27 and p53 in the context of various breast cancer subtypes.

Methods

Cyclin E1, cyclin D1, p53, p21 and p27 were evaluated with immunohistochemistry in 1077 formalin-fixed paraffin-embedded tissues from breast cancer patients who had been treated within clinical trials. Jaccard distances were computed for the markers and the resulted matrix was used for conducting unsupervised hierarchical clustering, in order to identify distinct groups correlating with prognosis.

Results

Luminal B and triple-negative (TNBC) tumors presented with the highest and lowest levels of cyclin D1 expression, respectively. By contrast, TNBC frequently expressed Cyclin E1, whereas ER-positive tumors did not. Absence of Cyclin D1 predicted for worse OS, while absence of Cyclin E1 for poorer DFS. The expression patterns of all examined proteins yielded 3 distinct clusters; (1) Cyclin D1 and/or E1 positive with moderate p21 expression; (2) Cyclin D1 and/or E1, and p27 positive, p53 protein negative; and, (3) Cyclin D1 or E1 positive, p53 positive, p21 and p27 negative or moderately positive. The 5-year DFS rates for clusters 1, 2 and 3 were 70.0%, 79.1%, 67.4% and OS 88.4%, 90.4%, 78.9%, respectively.

Conclusions

It seems that the expression of cell cycle regulators in the absence of p53 protein is associated with favorable prognosis in operable breast cancer.

[Redox-dependent mechanisms of regulation of breast epithelial cell proliferation]

Activation of free radical oxidation in different cell types, including breast epithelial cells, may result in damage to macromolecules, in particular, proteins taking part in regulation of cell proliferation and apoptosis. The glutathione, glutaredoxin and thioredoxin systems play an essential role in maintaining intracellular redox homeostasis. Due to this fact, modulation of cellular redox status under the effect of an SH group inhibitor and an SH group protector may be used as a model for studying the role of redox proteins and glutathione in regulating cell proliferation in different pathological processes. In this study we have evaluated the state of the thioredoxin, glutaredoxin and glutathione systems as well as their role in regulating proliferation of HBL-100 breast epithelial cells under redox status modulation with N-ethylmaleimide (NEM) and 1,4-dithioerythriol (DTE). Modulating the redox status of breast epithelial cells under the effect of NEM and DTE influences the functional activity of glutathione-dependent enzymes, glutaredoxin, thioredoxin, and thioredoxin reductase through changes in the GSH and GSSG concentrations. In HBL-100 cells under redox-status modulation, we have found an increase in the number of cells in the S-phase of the cell cycle and a decrease in the number of cells in the G0/G1 and G2/М phases, as opposed to the values in the intact culture. The proposed model of proliferative activity of cells under redox status modulation may be used for development of new therapeutic approaches for treatment of diseases accompanied by oxidative stress generation.

Cyclin G2 promotes cell cycle arrest in breast cancer cells responding to fulvestrant and metformin and correlates with patient survival

Definition of cell cycle control proteins that modify tumor cell resistance to estrogen (E2) signaling antagonists could inform clinical choice for estrogen receptor positive (ER+) breast cancer (BC) therapy. Cyclin G2 (CycG2) is upregulated during cell cycle arrest responses to cellular stresses and growth inhibitory signals and its gene, CCNG2, is directly repressed by E2-bound ER complexes. Our previous studies showed that blockade of HER2, PI3K and mTOR signaling upregulates CycG2 expression in HER2+ BC cells, and that CycG2 overexpression induces cell cycle arrest. Moreover, insulin and insulin-like growth factor-1 (IGF-1) receptor signaling strongly represses CycG2. Here we show that blockade of ER-signaling in MCF7 and T47D BC cell lines enhances the expression and nuclear localization of CycG2. Knockdown of CycG2 attenuated the cell cycle arrest response of E2-depleted and fulvestrant treated MCF7 cells. These muted responses were accompanied by sustained inhibitory phosphorylation of retinoblastoma (RB) protein, expression of cyclin D1, phospho-activation of ERK1/2 and MEK1/2 and expression of cRaf. Our work indicates that CycG2 can form complexes with CDK10, a CDK linked to modulation of RAF/MEK/MAPK signaling and tamoxifen resistance. We determined that metformin upregulates CycG2 and potentiates fulvestrant-induced CycG2 expression and cell cycle arrest. CycG2 knockdown blunts the enhanced anti-proliferative effect of metformin on fulvestrant treated cells. Meta-analysis of BC tumor microarrays indicates that CCNG2 expression is low in aggressive, poor-prognosis BC and that high CCNG2 expression correlates with longer periods of patient survival. Together these findings indicate that CycG2 contributes to signaling networks that limit BC.

Genistein suppresses leptin-induced proliferation and migration of vascular smooth muscle cells and neointima formation

Obesity is a strong risk factor for the development of cardiovascular diseases and is associated with a marked increase in circulating leptin concentration. Leptin is a peptide hormone mainly produced by adipose tissue and is regulated by energy level, hormones and various inflammatory mediators. Genistein is an isoflavone that exhibits diverse health‐promoting effects. Here, we investigated whether genistein suppressed the atherogenic effect induced by leptin. The A10 cells were treated with leptin and/or genistein, and then the cell proliferation and migration were analysed. The reactive oxygen species (ROS) and proteins levels were also measured, such as p44/42MAPK, cell cycle‐related protein (cyclin D1 and p21) and matrix metalloproteinase‐2 (MMP‐2). Immunohistochemistry and morphometric analysis were used for the neointima formation in a rat carotid artery injury model. Genistein (5 μM) significantly inhibited both the proliferation and migration of leptin (10 ng/ml)‐stimulated A10 cells. In accordance with these finding, genistein decreased the leptin‐stimulated ROS production and phosphorylation of the p44/42MAPK signal transduction pathway. Meanwhile, genistein reversed the leptin‐induced expression of cyclin D1, and cyclin‐dependent kinase inhibitor, p21. Genistein attenuated leptin‐induced A10 cell migration by inhibiting MMP‐2 activity. Furthermore, the leptin (0.25 mg/kg)‐augmented neointima formation in a rat carotid artery injury model was attenuated in the genistein (5 mg/kg body weight)‐treated group when compared with the balloon injury plus leptin group. Genistein was capable of suppressing the atherogenic effects of leptin in vitro and in vivo, and may be a promising candidate drug in the clinical setting.

The Silencing of CCND2 by Promoter Aberrant Methylation in Renal Cell Cancer and Analysis of the Correlation between CCND2 Methylation Status and Clinical Features

Cyclin D2 (CCND2) is a member of the D-type cyclins, which plays a pivotal role in cell cycle regulation, differentiation and malignant transformation. However, its expression status and relative regulation mechanism remains unclear in renal cell cancer (RCC). In our study, the mRNA expression level of CCND2 is down-regulated in 22/23 paired RCC tissues (p<0.05). In addition, its protein expression level is also decreased in 43/43 RCC tumor tissues compared with its corresponding non-malignant tissues (p<0.001). We further detected that CCND2 was down-regulated or silenced in 6/7 RCC cell lines, but expressed in “normal” human proximal tubular (HK-2) cell line. Subsequently, MSP and BGS results showed that the methylation status in CCND2 promoter region is closely associated with its expression level in RCC cell lines. Treatment with 5-Aza with or without TSA restored CCND2 expression in several methylated RCC cell lines. Among the 102 RCC tumors, methylation of CCND2 was detected in 29/102 (28%) cases. Only 2/23 (8.7%) adjacent non-malignant tissues showed methylation. We then analyzed the correlation of clinical features and its promoter methylation. Collectively, our data suggested that loss of CCND2 expression is closely associated with the promoter aberrant methylation.

The G1/S Specific Cyclin D2 Is a Regulator of HIV-1 Restriction in Non-proliferating Cells

Macrophages are a heterogeneous cell population strongly influenced by differentiation stimuli that become susceptible to HIV-1 infection after inactivation of the restriction factor SAMHD1 by cyclin-dependent kinases (CDK). Here, we have used primary human monocyte-derived macrophages differentiated through different stimuli to evaluate macrophage heterogeneity on cell activation and proliferation and susceptibility to HIV-1 infection. Stimulation of monocytes with GM-CSF induces a non-proliferating macrophage population highly restrictive to HIV-1 infection, characterized by the upregulation of the G1/S-specific cyclin D2, known to control early steps of cell cycle progression. Knockdown of cyclin D2, enhances HIV-1 replication in GM-CSF macrophages through inactivation of SAMHD1 restriction factor by phosphorylation. Co-immunoprecipitation experiments show that cyclin D2 forms a complex with CDK4 and p21, a factor known to restrict HIV-1 replication by affecting the function of the downstream cascade that leads to SAMHD1 deactivation. Thus, we demonstrate that cyclin D2 acts as regulator of cell cycle proteins affecting SAMHD1-mediated HIV-1 restriction in non-proliferating macrophages.

MiR-34a Promotes Osteogenic Differentiation of Human Adipose-Derived Stem Cells via the RBP2/NOTCH1/CYCLIN D1 Coregulatory Network

MiR-34a was demonstrated to be upregulated during the osteogenic differentiation of human adipose-derived stem cells (hASCs). Overexpression of miR-34a significantly increased alkaline phosphatase activity, mineralization capacity, and the expression of osteogenesis-associated genes in hASCs in vitro. Enhanced heterotopic bone formation in vivo was also observed upon overexpression of miR-34a in hASCs. Mechanistic investigations revealed that miR-34a inhibited the expression of retinoblastoma binding protein 2 (RBP2) and reduced the luciferase activity of reporter gene construct comprising putative miR-34a binding sites in the 3′ UTR of RBP2. Moreover, miR-34a downregulated the expression of NOTCH1 and CYCLIN D1 and upregulated the expression of RUNX2 by targeting RBP2, NOTCH1, and CYCLIN D1. Taken together, our results suggested that miR-34a promotes the osteogenic differentiation of hASCs via the RBP2/NOTCH1/CYCLIN D1 coregulatory network, indicating that miR-34a-targeted therapy could be a valuable approach to promote bone regeneration.

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MiR-34a promotes osteogenesis of hASCs in vitro and in vivo

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MiR-34a directly binds to the 3′ UTR of RBP2 mRNA in hASCs

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MiR-34a promotes osteogenesis of hASCs via the RBP2/NOTCH1/CYCLIN D1 network

Puberty-specific promotion of mammary tumorigenesis by a high animal fat diet

INTRODUCTION

Increased animal fat consumption is associated with increased premenopausal breast cancer risk in normal weight, but not overweight, women. This agrees with our previous findings in obesity-resistant BALB/c mice, in which exposure to a high saturated animal fat diet (HFD) from peripuberty through adulthood promoted mammary tumorigenesis. Epidemiologic and animal studies support the importance of puberty as a life stage when diet and environmental exposures affect adult breast cancer risk. In this study, we identified the effects of peripubertal exposure to HFD and investigated its mechanism of enhancing tumorigenesis.

METHODS

Three-week-old BALB/c mice fed a low-fat diet (LFD) or HFD were subjected to 7,12-dimethylbenz[a]anthracene (DMBA)-induced carcinogenesis. At 9 weeks of age, half the mice on LFD were switched to HFD (LFD-HFD group) and half the mice on HFD were switched to LFD (HFD-LFD group). Tumor gene expression was evaluated in association with diet and tumor latency.

RESULTS

The peripubertal HFD reduced the latency of DMBA-induced mammary tumors and was associated with tumor characteristics similar to those in mice fed a continuous HFD. Notably, short-latency tumors in both groups shared gene expression characteristics and were more likely to have adenosquamous histology. Both HFD-LFD and continuous HFD tumors showed similar gene expression patterns and early latency. Adult switch from HFD to LFD did not reverse peripubertal HFD tumor promotion. Increased proliferation, hyperplasia, and macrophages were present in mammary glands before tumor development, implicating these as possible effectors of tumor promotion. Despite a significant interaction between pubertal diet and carcinogens in tumor promotion, peripubertal HFD by itself produced persistent macrophage recruitment to mammary glands.

CONCLUSIONS

In obesity-resistant mice, peripubertal HFD is sufficient to irreversibly promote carcinogen-induced tumorigenesis. Increased macrophage recruitment is likely a contributing factor. These results underscore the importance of early life exposures to increased adult cancer risk and are consistent with findings that an HFD in normal weight premenopausal women leads to increased breast cancer risk. Notably, short-latency tumors occurring after peripubertal HFD had characteristics similar to human basal-like breast cancers that predominantly develop in younger women.

MiR-622 inhibited colorectal cancer occurrence and metastasis by suppressing K-Ras

Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide, with many oncogenes and anti-oncogenes involved. MicroRNAs (miRNAs) are a class of small, noncoding RNA molecules that can adjust downstream targets. Accumulating evidence has revealed that microRNAs govern the occurrence and development of cancer. Here, we studied the role of miR-622 in CRC and clarified the underlying mechanism. We detected that miR-622 was down-regulated in colorectal tumor tissues and cell lines and that miR-622 was lower in metastatic CRC tissues compared with that in non-metastatic specimens. Furthermore, we confirmed that miR-622 inhibited tumor proliferation and migration in vitro. Through dual-luciferase reporter assay, we found kirsten rat sarcoma (K-Ras) gene was the direct target of miR-622. More importantly, K-Ras overexpression can rescue the inhibitory effect of miR-622 on CRC development. All these data were validated in colon xenograft tumor model. MiR-622-K-Ras signal pathway was a potentially new direction in the development of screening target and therapeutic treatments for CRC. © 2015 Wiley Periodicals, Inc.

The effect of ferulic acid ethyl ester on leptin-induced proliferation and migration of aortic smooth muscle cells

Leptin is a peptide hormone, which has a central role in the regulation of body weight; it also exerts many potentially atherogenic effects. Ferulic acid ethyl ester (FAEE) has been approved for antioxidant properties. The aim of this study was to investigate whether FAEE can inhibit the atherogenic effects of leptin and the possible molecular mechanism of its action. Both of cell proliferation and migration were measured when the aortic smooth muscle cell (A10 cell) treated with leptin and/or FAEE. Phosphorylated p44/42MAPK, cell cycle-regulatory protein (for example, cyclin D1, p21, p27), β-catenin and matrix metalloproteinase-9 (MMP-9) proteins levels were also measured. Results demonstrated that leptin (10, 100 ng ml⁻¹) significantly increased the proliferation of cells and the phosphorylation of p44/42MAPK in A10 cells. The proliferative effect of leptin was significantly reduced by the pretreatment of U0126 (0.5 μM), a MEK inhibitor, in A10 cells. Meanwhile, leptin significantly increased the protein expression of cyclin D1, p21, β-catenin and decreased the expression of p27 in A10 cells. In addition, leptin (10 ng ml⁻¹) significantly increased the migration of A10 cells and the expression of MMP-9 protein. Above effects of leptin were significantly reduced by the pretreatment of FAEE (1 and 10 μM) in A10 cells. In conclusion, FAEE exerts multiple effects on leptin-induced cell proliferation and migration, including the inhibition of p44/42MAPK phosphorylation, cell cycle-regulatory proteins and MMP-9, thereby suggesting that FAEE may be a possible therapeutic approach to the inhibition of obese vascular disease.

Diacylglycerol kinase α promotes 3D cancer cell growth and limits drug sensitivity through functional interaction with Src

Diacylglycerol kinase (DGK)α converts diacylglycerol to phosphatidic acid. This lipid kinase sustains survival, migration and invasion of tumor cells, with no effect over untransformed cells, suggesting its potential as a cancer-specific target. Nonetheless the mechanisms that underlie DGKα specific contribution to cancer survival have not been elucidated. Using three-dimensional (3D) colon and breast cancer cell cultures, we demonstrate that DGKα upregulation is part of the transcriptional program that results in Src activation in these culture conditions. Pharmacological or genetic DGKα silencing impaired tumor growth in vivo confirming its function in malignant transformation. DGKα-mediated Src regulation contributed to limit the effect of Src inhibitors, and its transcriptional upregulation in response to PI3K/Akt inhibitors resulted in reduced toxicity. Src oncogenic properties and contribution to pharmacological resistance have been linked to its overactivation in cancer. DGKα participation in this central node helps to explain why its pharmacological inhibition or siRNA-mediated targeting specifically alters tumor viability with no effect on untransformed cells. Our results identify DGKα-mediated stabilization of Src activation as an important mechanism in tumor growth, and suggest that targeting this enzyme, alone or in combination with other inhibitors in wide clinical use, could constitute a treatment strategy for aggressive forms of cancer.

MiR-217 Promotes Tumor Proliferation in Breast Cancer via Targeting DACH1

Objective: The expression of DACH1 was frequently lost in human breast cancer, which significantly correlated with poor prognosis. Herein, we aim to investigate its underlying mechanisms.

Methods: The expression of miR-217 was detected by Taqman PCR. The mRNA and protein level of DACH1 were investigated by real time PCR and western blot. The dual-luciferase reporter system was used to determine the direct interaction between miR-217 and DACH1. A series of gain&loss of function assays were performed to measure the affects of miR-217 on tumor proliferation and cell cycle distribution.

Results: Compared to that in normal breast samples, the expression of miR-217 was significantly upregulated in breast cancer tissues. High level of miR-217 was notably correlated with highly histological grade, the triple negative subtype and advanced tumor stage. Moreover, the expression of miR-217 was negatively correlated with the expression of DACH1. The results of dual-luciferase reporter assay demonstrated that miR-217 directly targets and inhibits the transcriptive activity of DACH1. In vitro, treatment with miR-217 mimics significantly suppressed the proliferation of MCF-7 cells, induced G1 phase arrest and inhibited the expression of cyclin D1; while these effects were significantly reversed by the restoration of DACH1. In MDA-MB-231 cells, treatment with miR-217 inhibitors enhanced the cellular proliferation, promoted cell cycle progression and upregulated the expression of cyclin D1, which were neutralized by the pre-treatment of siRNA-DACH1. In vivo, inhibition of miR-217 significantly suppressed the xenografts growth and downregulated the expression of cyclin D1.

Conclusion: We found that miR-217 was commonly overexpressed in breast cancer, which could enhance tumor proliferation via promoting cell cycle progression. Moreover, the DACH1 (the cell fate determination factor) was identified as a novel target of miR-217. Our results proposed inhibiting miR-217 to be a potent therapeutic strategy for breast cancer.

Silica nanoparticles induced metabolic stress through EGR1, CCND, and E2F1 genes in human mesenchymal stem cells

The SiO2 synthesized in bulk form, adopting the conventional methods for application in food industry applications, may also contain nano-sized particles. On account of the unique physico-chemical properties, the SiO2 particulates, such as size and shape, cause metabolic toxicity in cells. Poor understanding of the molecular level nanotoxicity resulting from high-volume synthetic SiO2 exposures in humans is a serious issue, since these particles may also contribute to metabolic stress-mediated chronic diseases. In the present study, we examined the structural characteristics of these nano-sized silica particles adopting SEM and dynamic light scattering (DLS) and assessed the alterations in the cell cycle induced by these silica particles in human mesenchymal stem cells (hMSCs) adopting 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay, morphological changes in the cells adopting fluorescent microscopy, cell cycle analysis adopting flow cytometry, and the expression of genes linked to cell cycle (i.e., proliferating cell nuclear antigen (PCNA), early growth response protein (EGR1), E2F transcription factor (E2F1), cyclin D1, cyclin C, and cyclin D3) adopting qPCR. The SEM and DLS studies indicated that the commercial grade SiO2-NPs were in the nano-scale range. Alterations in the cytoplasmic organization, nuclear morphology, cell cycle progression, and expression of genes linked to cell cycle-dependent metabolic stress through EGR1, CCND, and E2F1 genes were the primary indicators of metabolic stress. Overall, the results of this study demonstrate that synthetic SiO2 acutely affects hMSC through cell cycle-dependent oxidative stress gene network. The toxicity mechanisms (both acute and chronic) of food grade silica should be investigated in greater depth with special reference to food safety.

Biphasic ER-α36-mediated estrogen signaling regulates growth of gastric cancer cells

To examine the expression patterns of ER-α36 and Cyclin D1 in human gastric cancer tissues and to investigate the effects of ER-α36-mediated estrogen signaling on the growth of gastric cancer cells, 117 samples of formalin-fixed and paraffin-embedded gastric cancer tumor tissues and 40 fresh gastric cancer tumor tissues were analyzed with immunohistochemistry assay and western blot analysis. ER-α36 expression was well correlated with gender (male:female ratio 2.88:1, P=0.01), invasion to serosa (P=0.01) as well as Cyclin D1 expression (P<0.01). The effects of different concentrations of estrogen on the growth of different gastric cancer cells and normal gastric cells as well as gastric cancer SGC7901 cells with different levels of ER-α36 expression were examined. SGC7901 cells with high levels of ER-α36 expression exhibited estrogen hypersensitivity, high growth rate and high levels of Cyclin D1 expression while SGC7901 cells with knocked-down levels of ER-α36 expression were insensitive to estrogen stimulation, grew slowly and expressed less Cyclin D1. Our results indicate that ER-α36 mediates biphasic estrogen signaling in the growth of gastric cancer cells.