Inhibition of cyclin D1 expression by cyclin D1 shRNAs in human oral squamous cell carcinoma cells is associated with increased cisplatin chemosensitivity

The effect and mechanism of erianin on the reversal of oxaliplatin resistance in human colon cancer cells

Multidrug resistance (MDR) is the main cause of chemotherapy failure in the treatment of colon cancer and the high expression of drug efflux protein P-gp is one of the main factors of MDR. P-gp expression is regulated by the signal transducer and activator of transcription 3 (STAT3) signaling pathway. In this study, human colon cancer oxaliplatin-resistant cells were treated with oxaliplatin combined with the natural product erianin. Then, we evaluated the impact of erianin on drug resistance, and explored the relationship between erianin-related oxaliplatin resistance and the Janus kinase 2/STAT3 signaling pathway in vitro. Our research showed that erianin could significantly inhibit the proliferation of human colon cancer oxaliplatin-resistant cells, and suppress the cell cycle of oxaliplatin-resistant cells in the G2/M phase, indicating that erianin could regulate the MDR phenotype of oxaliplatin-resistant cells, and its mechanism might be the inhibition of STAT3 signaling pathway and the significant reduction of P-gp expression. However, this study provides a theoretical basis for the clinical application of erianin in platinum-based chemotherapy for colon cancer.

Inhibition of Kpnβ1 mediated nuclear import enhances cisplatin chemosensitivity in cervical cancer

Background

Inhibition of nuclear import via Karyopherin beta 1 (Kpnβ1) shows potential as an anti-cancer approach. This study investigated the use of nuclear import inhibitor, INI-43, in combination with cisplatin.

Methods

Cervical cancer cells were pre-treated with INI-43 before treatment with cisplatin, and MTT cell viability and apoptosis assays performed. Activity and localisation of p53 and NFκB was determined after co-treatment of cells.

Results

Pre-treatment of cervical cancer cells with INI-43 at sublethal concentrations enhanced cisplatin sensitivity, evident through decreased cell viability and enhanced apoptosis. Kpnβ1 knock-down cells similarly displayed increased sensitivity to cisplatin. Combination index determination using the Chou-Talalay method revealed that INI-43 and cisplatin engaged in synergistic interactions. p53 was found to be involved in the cell death response to combination treatment as its inhibition abolished the enhanced cell death observed. INI-43 pre-treatment resulted in moderately stabilized p53 and induced p53 reporter activity, which translated to increased p21 and decreased Mcl-1 upon cisplatin combination treatment. Furthermore, cisplatin treatment led to nuclear import of NFκB, which was diminished upon pre-treatment with INI-43. NFκB reporter activity and expression of NFκB transcriptional targets, cyclin D1, c-Myc and XIAP, showed decreased levels after combination treatment compared to single cisplatin treatment and this associated with enhanced DNA damage.

Conclusions

Taken together, this study shows that INI-43 pre-treatment significantly enhances cisplatin sensitivity in cervical cancer cells, mediated through stabilization of p53 and decreased nuclear import of NFκB. Hence this study suggests the possible synergistic use of nuclear import inhibition and cisplatin to treat cervical cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-07819-3.

Plasma-Derived Inflammatory Proteins Predict Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a major concern with high morbidity and mortality worldwide, even with the current knowledge and the advancement in treatment. OSCCs diagnosed at late-stage often require wide-excision with or without neck dissection, radiotherapy, or chemotherapy. When deemed successful, treatment often results in diminished quality of life, impaired function, and disfigurement. Strategies for early detection are urgently needed for patients afflicted with this disease. Inflammatory protein plasma biomarkers have shown to be potential tests for early detection and disease monitoring in several cancers. There has been no study on inflammation-related plasma biomarkers in OSCC. The objectives of the study were to use a multiplex approach to screen plasma-derived biomarkers and to examine the association of measurable proteins with OSCC. A total of 260 plasma samples (210 OSCC and 50 normal controls) were collected to measure for concentration of inflammatory related biomarkers using electrochemiluminescence multiplex assay. After screening of 82 potential biomarkers of the first 160 OSCC, 16 cytokines, chemokines, and growth factors were identified and verified in the second set of samples containing 50 OSCC and 50 normal. After adjustment of age and batch effects, the adjusted differential expression analysis showed that the OSCCs were markedly lower in 14 biomarkers and significantly higher level of interleukin 1 receptor antagonist (IL1Ra). By performing unsupervised clustering analysis, we observed distinctive groups of normal and two subgroups of OSCC. Linear regression of IL2, IL1Ra, and macrophage inhibitory factor (MIF) showed high accuracy in classifying OSCC with sensitivity of 0.96 and specificity of 0.92. In conclusion, this is the first paper to identify potential inflammatory plasma protein biomarkers of patients with OSCC. With further validation, the set of biomarkers can potentially be used to assist in early detection of OSCC when the disease is localized and in more treatable stage.

Sulforaphane regulates apoptosis- and proliferation‑related signaling pathways and synergizes with cisplatin to suppress human ovarian cancer

Ovarian cancer is currently the most life‑threatening type of gynecological malignancy with limited treatment options. Therefore, improved targeted therapies are required to combat ovarian cancer across the world. Sulforaphane is found in raw cruciferous vegetables. The chemotherapeutic and anti‑carcinogenic properties of sulforaphane have been demonstrated, however, the underlying mechanisms remain to be fully elucidated, particularly in ovarian cancer. In the present study, the possibility of repurposing sulforaphane as an anti‑ovarian cancer agent was examined. Cell viability and colony formation assay were used to test the anticancer efficiency of sulforaphane. Then wound healing assay, migration assay, cell cycle and apoptosis assays were used to detect how the drug worked on the cells. The mechanism of sulforaphane was investigated by western blot analysis. It was found that sulforaphane effectively suppressed the progression of human ovarian cancer cell proliferation, migration and cell cycle, and promoted apoptosis. Sulforaphane inhibited multiple cancer‑associated signaling pathways, including B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated X protein, cytochrome c, Caspase‑3, phosphorylated AKT, phosphorylated nuclear factor‑κB, P53, P27, Cyclin‑D1 and cMyc, and reduced the expression levels of human epidermal growth factor receptor 2 in human ovarian cancer cells. Sulforaphane synergized with cisplatin to suppress the cancer cell proliferation and enhance ovarian cancer cell apoptosis. Xenograft experiments in vivo confirmed that sulforaphane effectively suppressed tumor growth by inhibiting ovarian cancer cell proliferation through targeting tumor‑related signals. The results indicated that sulforaphane may be repurposed as an effective anti‑ovarian cancer agent, with further preclinical or clinical investigations required.

Protective effect of epigenetic silencing of CyclinD1 against spinal cord injury using bone marrow-derived mesenchymal stem cells in rats

This study focuses on the protective effect of epigenetic silencing of CyclinD1 against spinal cord injury (SCI) using bone marrow-derived mesenchymal stem cells (BMSCs) in rats. Eighty-eight adult female Wistar rats were randomly assigned into the sham group, the control group, the si-CyclinD1 + BMSCs group and the BMSCs group. CyclinD1 protein and mRNA expressions after siRNA transfection were detected by Western blotting and qRT-PCR. The siRNA-CyclinD1 BMSCs were transplanted into rats in the si-CyclinD1 + BMSCs group using stereotaxic method 6 hr after SCI. Hindlimb locomotor performance was determined using inclined plane test and Basso-Beattie-Bresnahan (BBB) locomotor rating scale. Expressions of glial fibrillary acidic protein (GFAP) and nerve growth factor (NGF) were detected by immunohistochemistry. Inclined plane and BBB scores in the control, si-CyclinD1 + BMSCs, and BMSCs groups were significantly lower than the sham group, but these scores were evidently decreased in the control group and increased in the si-CyclinD1 + BMSCs group compared with the BMSCs group. The repair degree of spinal cord tissues of rats in the si-CyclinD1 + BMSCs group was obvious than the BMSCs group. GFAP and NGF protein expressions were markedly decreased in the control, si-CyclinD1 + BMSCs and BMSCs groups when compared with the sham group. GFAP- and NGF-positive cells were significantly increased in the si-CyclinD1 + BMSCs group while decreased in the control group. Our study provides evidence that epigenetic silencing of CyclinD1 using BMSCs might accelerate the repair of SCI in rats.

Biological evaluation of a halogenated triterpenoid, 2α-bromo-dihydrobelulonic acid as inhibitor of human topoisomerase IIα and HeLa cell proliferation

BACKGROUND

The pentacyclic lupane-type (6-6-6-6-5 type) triterpenoid, Betulinic acid (BA) is a potent inhibitor of topoisomerases and is of immense interest as anticancer drugs. However, the compound being highly lipophilic, has limited in vivo uptake capacity. BA derivatives with halogen substituent at C-2 have improved membrane permeability and cytotoxicity against cancer cells.

AIM

The halogenated triterpenoid, 2α-bromo-dihydrobetulonic acid (B1) was synthesized from betulinic acid (BA) isolated from Bischofia javanica. Aim of the study was to determine whether B1 could act as a more efficient inhibitor of Topo IIα activity and HeLa cell proliferation, in comparison to BA.

RESULT

B1 displayed efficient inhibition of DNA relaxation activity of topoisomerase IIα and the inhibitory effect was markedly improved upon pre-incubation of the compound with enzyme. Topoisomerase IIα inhibition by B1 was relieved in presence of increasing concentrations of DNA suggesting the compound as a reversible catalytic inhibitor. Subsequent UV and fluorescence spectroscopy studies indicated that B1 interacts and intercalates with DNA at concentrations signicantly greater than that required for topoisomerase IIα inhibition. The compound showed cytotoxic activity against HeLa cells with significantly lower IC₅₀ value (7.5 μM) as compared to that of BA (30 μM) and had very low damaging/cytotoxic effect on normal cells. Treatment of B1 impaired HeLa cell proliferation by inducing Go-G1 arrest through lowered expression of cyclin D1 and PCNA polypeptides, and enhanced expression of p21. B1 treatment also increased the accumulation of early and late apoptotic cells in a concentration dependent manner as indicated by annexin V-FITC/PI binding assay.

Knockdown of Long Non-Coding RNA KCNQ1OT1 Restrained Glioma Cells' Malignancy by Activating miR-370/CCNE2 Axis

Accumulating evidence has highlighted the potential role of long non-coding RNAs (lncRNAs) as biomarkers and therapeutic targets in solid tumors. Here, we elucidated the function and possible molecular mechanisms of lncRNA KCNQ1OT1 in human glioma U87 and U251 cells. Quantitative Real-Time polymerase chain reaction (qRT-PCR) demonstrated that KCNQ1OT1 expression was up-regulated in glioma tissues and cells. Knockdown of KCNQ1OT1 exerted tumor-suppressive function in glioma cells. Moreover, a binding region was confirmed between KCNQ1OT1 and miR-370 by dual-luciferase assays. qRT-PCR showed that miR-370 was down-regulated in human glioma tissue and cells. In addition, restoration of miR-370 exerted tumor-suppressive function via inhibiting cell proliferation, migration and invasion, while promoting the apoptosis of human glioma cells. Knockdown of KCNQ1OT1 decreased the expression level of Cyclin E2 (CCNE2) by binding to miR-370. Further, miR-370 bound to CCNE2 3′UTR region and decreased the expression of CCNE2. These results provided a comprehensive analysis of KCNQ1OT1-miR-370-CCNE2 axis in human glioma cells and might provide a novel strategy for glioma treatment.

Sarcosine Up-Regulates Expression of Genes Involved in Cell Cycle Progression of Metastatic Models of Prostate Cancer

The effects of sarcosine on the processes driving prostate cancer (PCa) development remain still unclear. Herein, we show that a supplementation of metastatic PCa cells (androgen independent PC-3 and androgen dependent LNCaP) with sarcosine stimulates cells proliferation in vitro. Similar stimulatory effects were observed also in PCa murine xenografts, in which sarcosine treatment induced a tumor growth and significantly reduced weight of treated mice (p < 0.05). Determination of sarcosine metabolism-related amino acids and enzymes within tumor mass revealed significantly increased glycine, serine and sarcosine concentrations after treatment accompanied with the increased amount of sarcosine dehydrogenase. In both tumor types, dimethylglycine and glycine-N-methyltransferase were affected slightly, only. To identify the effects of sarcosine treatment on the expression of genes involved in any aspect of cancer development, we further investigated expression profiles of excised tumors using cDNA electrochemical microarray followed by validation using the semi-quantitative PCR. We found 25 differentially expressed genes in PC-3, 32 in LNCaP tumors and 18 overlapping genes. Bioinformatical processing revealed strong sarcosine-related induction of genes involved particularly in a cell cycle progression. Our exploratory study demonstrates that sarcosine stimulates PCa metastatic cells irrespectively of androgen dependence. Overall, the obtained data provides valuable information towards understanding the role of sarcosine in PCa progression and adds another piece of puzzle into a picture of sarcosine oncometabolic potential.

Phase I trial of palbociclib, a selective cyclin dependent kinase 4/6 inhibitor, in combination with cetuximab in patients with recurrent/metastatic head and neck squamous cell carcinoma

OBJECTIVES

To test the safety of the CDK4/6 inhibitor palbociclib with cetuximab in patients with recurrent/metastatic head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

A phase I trial using 3+3 design was performed to determine the dose limiting toxicity (DLT) and maximum tolerated dose (MTD) of palbociclib with standard dose weekly cetuximab. Palbociclib was administered orally days 1-21 every 28days: dose level 1 (100mg/d) and 2 (125mg/d; approved monotherapy dose). Pharmacokinetic assessments were performed on cycle 2, day 15. Cyclin D1, p16(INK4a), and Rb protein expression were measured on pre-treatment tumor. Tumor response was assessed using RECIST1.1.

RESULTS

Nine patients (five p16(INK4a) negative; four positive) were enrolled across dose levels 1 (n=3) and 2 (n=6) and none experienced a DLT. A MTD of palbociclib was not reached. Myelosuppression was the most common adverse event. Six of nine patients had cetuximab-resistant and 4/9 had platin-resistant disease. Disease control (DC) occurred in 89%, including partial response (PR) in two (22%) and stable disease in six (67%) patients. PRs occurred in p16(INK4a) negative HNSCC. Five patients (56%) had measurable decreases in tumor target lesions. In cetuximab-resistant HNSCC, best tumor response was PR in 1 and DC in 5 and median TTP was 112days (range: 28-168). In platin-resistant HNSCC, best tumor response: PR in 1, DC in 3 and median TTP was 112days (range: 28-112). The Cmax and AUC0-24h appeared comparable in patients receiving 125 vs 100mg dose of palbociclib.

CONCLUSION

This trial, the first to evaluate a CDK4/6 inhibitor in HNSCC, determined that palbociclib 125mg/day on days 1-21 every 28days with cetuximab was safe. Tumor responses were observed, even in cetuximab- or platin-resistant disease.

Redox Control of Multidrug Resistance and Its Possible Modulation by Antioxidants

Clinical efficacy of anticancer chemotherapies is dramatically hampered by multidrug resistance (MDR) dependent on inherited traits, acquired defence against toxins, and adaptive mechanisms mounting in tumours. There is overwhelming evidence that molecular events leading to MDR are regulated by redox mechanisms. For example, chemotherapeutics which overrun the first obstacle of redox-regulated cellular uptake channels (MDR1, MDR2, and MDR3) induce a concerted action of phase I/II metabolic enzymes with a temporal redox-regulated axis. This results in rapid metabolic transformation and elimination of a toxin. This metabolic axis is tightly interconnected with the inducible Nrf2-linked pathway, a key switch-on mechanism for upregulation of endogenous antioxidant enzymes and detoxifying systems. As a result, chemotherapeutics and cytotoxic by-products of their metabolism (ROS, hydroperoxides, and aldehydes) are inactivated and MDR occurs. On the other hand, tumour cells are capable of mounting an adaptive antioxidant response against ROS produced by chemotherapeutics and host immune cells. The multiple redox-dependent mechanisms involved in MDR prompted suggesting redox-active drugs (antioxidants and prooxidants) or inhibitors of inducible antioxidant defence as a novel approach to diminish MDR. Pitfalls and progress in this direction are discussed.

Biomarkers predicting chemotherapy response in head and neck squamous cell carcinoma: a review

BACKGROUND

Biomarkers are increasingly being used in many cancers to select patients for oncological treatment paradigms based on their inherent genetic properties. However, in head and neck cancers, there are no personalised therapies available outside the context of a clinical trial. A number of studies suggest there are intrinsic tumour properties of head and neck cancers that affect their response to chemotherapeutic agents. This paper aimed to review their evidence base.

METHOD

A narrative review was conducted following a search of the PubMed database.

RESULTS AND CONCLUSION

The review identified a number of biomarkers predicting response to chemotherapy in head and neck cancers. The paper discusses these in detail, and explores where future research could be directed in order to deliver personalised therapies for patients with head and neck cancers.

RNA interference of Biot2 induces G1 phase arrest and apoptosis in mouse colorectal cancer cell line

Biot2 is a tumor-associated antigen, and it is a novel gene (GenBank EF100607) that was first identified with the SEREX technique and named by our laboratory. It is highly expressed in cancer cells and testis, with low or no expression in normal tissues. In our previous study, RNA interference of human Biot2 can inhibit tumor cell growth, and it is associated with poor prognosis of patients in clinical study; however, the mechanism of Biot2 that effects tumor growth is not yet clear. Here, in this study, we explore further the mechanism of Biot2 by silencing Biot2 in CT26 cells. It provides some theoretical basis for Biot2 as a new target for gene therapy. In CT26 cells, the expression of Biot2 was downregulated by Biot2-shRNA. It also promoted G₁ phase arrest, the expression of p16 and p21, and cell apoptosis. In the mouse model, the tumor volume and the expression of PCNA of the Biot2-shRNA group significantly decreased. These results suggest that silencing Biot2 in CT26 cells by RNA interference can inhibit cell growth in vitro and in vivo. It also induces cell cycle arrest in the G₁ phase and apoptosis throughout regulation of p16 and p21. Taken together, our data demonstrate that Biot2 can be a potential target of gene therapy.

MicroRNAs Used in Combination with Anti-Cancer Treatments Can Enhance Therapy Efficacy

MicroRNAs (miRNAs), a recently discovered class of small non-coding RNAs, constitute a promising approach to anti-cancer treatments when they are used in combination with other agents. MiRNAs are evolutionarily conserved non-coding RNAs that negatively regulate gene expression by binding to the complementary sequence in the 3'-untranslated region (UTR) of target genes. MiRNAs typically suppress gene expression by direct association with target transcripts, thus decreasing the expression levels of target proteins. The delivery to cells of synthetic miRNAs that mimic endogenous miRNA targeting genes involved in the DNA-Damage Response (DDR) can perturb the process, making cells more sensitive to chemotherapy or radiotherapy. This review examines how cells respond to combined therapy and it provides insights into the role of miRNAs in targeting the DDR repair pathway when they are used in combination with chemical compounds or ionizing radiation to enhance cellular sensitivity to treatments.

Emerging strategies to overcome the resistance to current mTOR inhibitors in renal cell carcinoma

The mammalian target of rapamycin (mTOR) has emerged as an attractive cancer therapeutic target. Treatment of metastatic renal cell carcinoma (mRCC) has improved significantly with the advent of agents targeting the mTOR pathway, such as temsirolimus and everolimus. Unfortunately, a number of potential mechanisms that may lead to resistance to mTOR inhibitors have been proposed. In this paper, we discuss the mechanisms underlying resistance to mTOR inhibitors, which include the downstream effectors of the phosphoinositide 3-kinase (PI3K)/AKT/mTOR pathway, the activation of hypoxia-inducible factor (HIF), the PIM kinase family, PTEN expression, elevated superoxide levels, stimulation of autophagy, immune cell response and ERK/MAPK, Notch and Aurora signaling pathways. Moreover, we present an updated analysis of clinical trials available on PubMed Central and www.clinicaltrials.gov, which were pertinent to the resistance to rapalogs. The new frontier of inhibiting the mTOR pathway is to identify agents targeting the feedback loops and cross talks with other pathways involved in the acquired resistance to mTOR inhibitors. The true goal will be to identify biomarkers predictive of sensitivity or resistance to efficiently develop novel agents with the aim to avoid toxicities and to better choose the active drug for the right patient.

Lentivirus-mediated shRNA targeting of cyclin D1 enhances the chemosensitivity of human gastric cancer to 5-fluorouracil

Gastric cancer is one of the major public health problems. Despite new chemotherapeutic treatments, the prognosis of gastric cancer remains poor. 5-Fluorouracil (5-FU) is used as a standard chemotherapy drug in gastric cancer. However, 5-FU resistance develops frequently and is a main cause of chemotherapy failure in human gastric cancer. Overexpression of cyclin D1 is related to rapid cell growth, a poor prognosis and increased chemoresistance in several types of cancers. In this study, we investigated whether treatment of gastric cancer cells with shRNA targeting cyclin D1 (ShCCND1) or 5-FU, alone or in combination, influences the activation of phosphorylated AKT (pAKT) and pNFκB, which are markers that are increased in 5-FU chemoresistance. We also investigated the effect of combined treatment with ShCCND1 and 5-FU on cell growth and chemosensitivity to 5-FU in the gastric cancer cell line AGS. The data showed that ShCCND1-mediated cyclin D1 downregulation in AGS cells significantly inhibited cell proliferation, cell mobility and clonogenicity. In addition, combined treatment with ShCCND1 and 5-FU significantly decreased the survival rate of AGS cells, compared to single-treatment with either agent. These results demonstrated that ShCCND1 increases 5-FU chemosensitivity, a conclusion that is also supported by the concomitant reduction in expression of pAKT and pNFκB, increase of G1 arrest and induction of apoptosis. Taken together, these data provide further evidence that therapeutic strategies targeting cyclin D1 may have the dual advantage of suppressing the growth of cancer cells, while enhancing their chemosensitivity.

RETRACTED: Tea polyphenols enhance cisplatin chemosensitivity in cervical cancer cells via induction of apoptosis

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief. Multiple figures in this article appear to be falsified/fabricated. Figure 2A and C. The representative dot plots from the EGCG (15ug/ml)+CDDP (10ug/ml) and TF (15ug/ml) groups appear to be duplicated. Figures 3, 4 and 6. Multiple Western blot bands appear to be rotated and reused throughout Figure 3 (A and B); 4 (A and B) and 6 (A, B, C). In particular, the Cytochrome-c blot in Figure 3B is duplicated and flipped in Figure 6B as p-NFKB. The p53 blot in Figure 3B is duplicated in Figure 6C as p-NFKB. The B-actin blot in Figure 3B is shown as an unmarked control lane (flipped in Figure 6B. The p53 band in Figure 3C is very similar to the Caspase 9 blot in Figure 4B and is cropped and duplicated in Figure 6A as p-NFKB by cisplatin in SiHa cells. The Caspase 3 blot in Figure 4A is rotated and flipped and appears in Figure 6B as p-IKBa.

In vitro and in vivo anti-tumor effect of metformin as a novel therapeutic agent in human oral squamous cell carcinoma

Background

Metformin, which is widely used as an antidiabetic agent, has recently been reported to reduce cancer risk and improve prognosis in certain malignancies. However, the specific mechanisms underlying the effect of metformin on the development and progression of several cancers including oral squamous cell carcinoma (OSCC) remain unclear. In the present study, we investigated the effects of metformin on OSCC cells in vitro and in vivo.

Methods

OSCC cells treated with or without metformin were counted using a hemocytometer. The clonogenic ability of OSCC cells after metformin treatment was determined by colony formation assay. Cell cycle progression and apoptosis were assessed by flow cytometry, and the activation of related signaling pathways was examined by immunoblotting. The in vivo anti-tumor effect of metformin was examined using a xenograft mouse model. Immunohistochemistry and TUNEL staining were used to determine the expression of cyclin D1 and the presence of apoptotic cells in tumors from mice treated with or without metformin.

Results

Metformin inhibited proliferation in the OSCC cell lines CAL27, WSU-HN6 and SCC25 in a time- and dose-dependent manner, and significantly reduced the colony formation of OSCC cells in vitro. Metformin induced an apparent cell cycle arrest at the G0/G1 phase, which was accompanied by an obvious activation of the AMP kinase pathway and a strongly decreased activation of mammalian target of rapamycin and S6 kinase. Metformin treatment led to a remarkable decrease of cyclin D1, cyclin-dependent kinase (CDK) 4 and CDK6 protein levels and phosphorylation of retinoblastoma protein, but did not affect p21 or p27 protein expression in OSCC cells. In addition, metformin induced apoptosis in OSCC cells, significantly down-regulating the anti-apoptotic proteins Bcl-2 and Bcl-xL and up-regulating the pro-apoptotic protein Bax. Metformin also markedly reduced the expression of cyclin D1 and increased the numbers of apoptotic cells in vivo, thus inhibiting the growth of OSCC xenografts.

Conclusions

Our data suggested that metformin could be a potential candidate for the development of new treatment strategies for human OSCC.

Toll-like receptor-9 agonists increase cyclin D1 expression partly through activation of activator protein-1 in human oral squamous cell carcinoma cells

Increasing evidence suggests that malignant transformation can result from chronic infection, and Toll-like receptors (TLRs) may play an important role in this process. We have previously reported that the increased expression of TLR-9 is associated with tumor cell proliferation in oral cancer. However, the mechanisms involved have not been elucidated. The aim of this study was to investigate whether CpG-oligodeoxynucleotides (CpG-ODN), a special TLR-9 agonist, is able to exert the proliferation-promoting effect in human oral squamous cell carcinoma (OSCC), and to explore the possible underlying molecular mechanism. Flow cytometry, MTT, and colony formation assay were used to evaluate cell proliferation and cell cycle distribution. The mRNA and protein levels were analyzed by quantitative RT-PCR and Western blot assay. Luciferase reporter gene, EMSA, and ChIP assays were used to detect the activity of activator protein-1 (AP-1) and nuclear factor-κB (NF-κB) in HB cells. Results showed that CpG-ODN could stimulate proliferation of HB cells in a dose- and time-dependent manner with a promoted G(1) /S cell cycle progression. Increased cyclin D1 expression was detected in the nuclear region after CpG-ODN treatment. Moreover, CpG-ODN promoted nuclear translocation and activation of AP-1, which appeared to be required for TLR-9-mediated cyclin D1 expression and subsequently cell proliferation, but seemed to have little impact on NF-κB activity. Our results indicate that CpG-ODN stimulates tumor cell proliferation through TLR-9-mediated AP-1-activated cyclin D1 expression in OSCC HB cells. Pharmacologic inhibition of the TLR-9/AP-1/cyclin D1 pathway may be a new therapeutic approach for prevention as well as treatment of OSCC.

CyclinD1 protein plays different roles in modulating chemoresponses in MCF7 and MDA-MB231 cells

Background:

CyclinD1 is an essential sensor and activator of cell cycle initiation and progression; overexpression of cyclinD1 is linked to various human cancers, including breast cancer. The elevated cyclinD1 in some types of cancers is believed to be associated with tumor progression and response to systemic treatments.

Aims:

In this study, we anticipate to address the questions in human breast cancer; the function of cyclinD1 in mediating chemoresponses; and the signaling pathway cooperating with cyclinD1 to interfere with the drug functions.

Materials and Methods:

Using the cell clones, concurrent ectopic expression of the wild-type or K112E-mutated human cyclinD1 protein in the MCF7 and MDA-MB231 (MB231) breast cancer cells to study the function of cyclinD1 in responses to the chemotherapeutic treatments. Three drugs, cisplatin (CDDP), 5-fluorouracil (5-FU), and Gemzar were used in this study; the 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, cell cycle and cell death analysis, clonogenic survival assay, acridine orange (AO)/ethidium bromide (EB) staining, and Western blot assay were conducted to evaluate the drugs’ effects in the cell clones.

Results:

The cell clones expressing the D1 protein in MCF7 and MB231 cells result in distinct effects on the responses to chemotherapeutic treatments. Particularly with Gemzar, ectopic expression of cyclinD1 protein in MCF7 cells results in a potentiated effect, which is CDK4 kinase activity dependent, whereas in MB231 cells, an opposite effect was observed. Moreover, our results suggested that the distinct chemosensitivities among those cell clones were not resulted from accelerated cell cycle, cell proliferation driven by the cyclinD1CDK4/6-Rb-E2F signaling chain, rather, they were results of the cell cycle-independent functions led by cyclinD1 alone or in complex with CDK4.

Conclusions:

Our results suggest that the functions of cyclinD1 protein in modulating chemoresponses in the MCF7 and MB231 cells are independent to its function as cell cycle initiator through activation of CDK4/6. Furthermore, the signals modulated by cyclinD1 upon treatment are determined by the drug and the cellular network.

Epigenetic and genetic alterations-based molecular classification of head and neck cancer

The long-term survival rates for patients diagnosed with advanced head and neck cancer (HNC) remain poor. Many perplexing factors, including etiology and comorbidity, lead to different molecular malfunctions of HNC cells and determine the prognosis of the disease. Traditional diagnostic methods are limited in that they fail to provide an effective classification diagnosis, such as a more precise prediction of prognosis and decisions for personalized treatment regimens. Recently, molecular biology techniques, especially epigenetic and genetic techniques, have been developed that have enabled us to gain a greater insight into the molecular pathways underlying the cancers. Translating the research into a format that will facilitate effective molecular classification, support personalized treatment and determine prognosis remains a challenge. In this review, the authors provide an overview of cancer epigenetic and genetic alterations, tissue banks, and several promising biomarkers or candidates that may ultimately prove to be beneficial in a clinical setting for patients with HNC.

Baicalein induces G1 arrest in oral cancer cells by enhancing the degradation of cyclin D1 and activating AhR to decrease Rb phosphorylation

Baicalein is a flavonoid, known to have anti-inflammatory and anti-cancer effects. As an aryl hydrocarbon receptor (AhR) ligand, baicalein at high concentrations blocks AhR-mediated dioxin toxicity. Because AhR had been reported to play a role in regulating the cell cycle, we suspected that the anti-cancer effect of baicalein is associated with AhR. This study investigated the molecular mechanism involved in the anti-cancer effect of baicalein in oral cancer cells HSC-3, including whether such effect would be AhR-mediated. Results revealed that baicalein inhibited cell proliferation and increased AhR activity in a dose-dependent manner. Cell cycle was arrested at the G1 phase and the expression of CDK4, cyclin D1, and phosphorylated retinoblastoma (pRb) was decreased. When the AhR was suppressed by siRNA, the reduction of pRb was partially reversed, accompanied by a decrease of cell population at G1 phase and an increase at S phase, while the reduction of cyclin D1 and CDK4 did not change. This finding suggests that the baicalein activation of AhR is indeed associated with the reduction of pRb, but is independent of the reduction of cyclin D1 and CDK4. When cells were pre-treated with LiCl, the inhibitor of GSK-3β, the decrease of cyclin D1 was blocked and the reduction of pRb was recovered. The data indicates that in HSC-3 the reduction of pRb is both mediated by baicalein through activation of AhR and facilitation of cyclin D1 degradation, which causes cell cycle arrest at the G1 phase, and results in the inhibition of cell proliferation.

Up-regulation of enhancer of zeste homolog 2 is associated positively with cyclin D1 overexpression and poor clinical outcome in head and neck squamous cell carcinoma

BACKGROUND

The authors previously observed that enhancer of zeste homolog 2 (EZH2) overexpression was associated significantly with the development of oral cancer. In the current study, they investigated whether EZH2 can function as a prognostic predictor for patients with head and neck squamous cell carcinoma (HNSCC).

METHODS

Expression levels of EZH2 in HNSCC cells were detected using reverse transcriptase-polymerase chain reaction (PCR) and Western blot analyses. In addition, the effects of EZH2 ablation on the proliferation and invasion of HNSCC cells were investigated through small interfering RNA (siRNA)-mediated knockdown. Real-time PCR and immunohistochemistry were used to evaluate EZH2 and cyclin D1 expression in 46 HNSCC samples, and the expression levels also were re-evaluated in 124 independent samples by immunohistochemistry.

RESULTS

EZH2 expression was elevated remarkably in HNSCC specimens and cell lines. Upon EZH2 silencing, the proliferation and invasion of HNSCC cells were remarkably suppressed. EZH2 expression frequently was correlated with cyclin D1 expression (P = .034) and tumor differentiation (P = .020). In addition, both EZH2 messenger RNA levels and EZH2 protein levels were strongly associated with signs of histologic severity (P = .012 and P = .032, respectively). Univariate analysis revealed that high EZH2 expression was associated with worse overall survival (P = .001) and disease-free survival (P = .002). The combined expression of EZH2 and cyclin D1 had superior prognostic ability for patients with HNSCC than the expression of either marker alone. In multivariate analysis, EZH2 expression was identified as an independent predictor of overall and disease-free survival.

CONCLUSIONS

The current results indicated that EZH2 is an independent prognostic indicator for patients with HNSCC. In addition, an analysis of the combined expression of EZH2 and cyclin D1 can serve as a more powerful prognostic predictor for patients with HNSCC.

CCND1 as a predictive biomarker of neoadjuvant chemotherapy in patients with locally advanced head and neck squamous cell carcinoma

Background

Cyclin D1 (CCND1) has been associated with chemotherapy resistance and poor prognosis. In this study, we tested the hypothesis that CCND1 expression determines response and clinical outcomes in locally advanced head and neck squamous cell carcinoma (HNSCC) patients treated with neoadjuvant chemotherapy followed by surgery and radiotherapy.

Methodology and Findings

224 patients with HNSCC were treated with either cisplatin-based chemotherapy followed by surgery and radiotherapy (neoadjuvant group, n = 100) or surgery and radiotherapy (non-neoadjuvant group, n = 124). CCND1 expression was assessed by immunohistochemistry. CCND1 levels were analyzed with chemotherapy response, disease-free survival (DFS) and overall survival (OS). There was no significant difference between the neoadjuvant group and non-neoadjuvant group in DFS and OS (p = 0.929 and p = 0.760) when patients treated with the indiscriminate administration of cisplatin-based chemotherapy. However, in the neoadjuvant group, patients whose tumors showed a low CCND1 expression more likely respond to chemotherapy (p<0.001) and had a significantly better OS and DFS than those whose tumors showed a high CCND1 expression (73% vs 8%, p<0.001; 63% vs 6%, p<0.001). Importantly, patients with a low CCND1 expression in neoadjuvant group received more survival benefits than those in non-neoadjuvant group (p = 0.016), however patients with a high CCND1 expression and treated with neoadjuvant chemotherapy had a significantly poor OS compared to those treated with surgery and radiotherapy (p = 0.032). A multivariate survival analysis also showed CCND1 expression was an independent predictive factor (p<0.001).

Conclusions

This study suggests that some but not all patients with HNSCC may benefit from neoadjuvant chemotherapy with cisplatin-based regimen and CCND1 expression may serve as a predictive biomarker in selecting patients undergo less than two cycles of neoadjuvant chemotherapy.

Cyclin D1 predicts the prognosis of advanced serous ovarian cancer

We previously reported that cyclin E (CCNE1) amplification is strongly associated with resistance to treatment in serous ovarian cancer by high-resolution oligonucleotide copy number analysis. Dysregulation of cell cycle control has been implicated as the key event in human oncogenesis, and aberrant expression of G1-S phase-related genes in particular has been reported in epithelial ovarian cancer (EOC). Nevertheless, there are conflicting results concerning the prognostic values of these abnormalities in EOC. This study focused on advanced serous EOC cases and investigated the association between the expression of G1-S phase-regulatory proteins and clinicopathological parameters. The utility of these proteins as prognostic factors was assessed, and whether these targets reflect chemoresistance of advanced serous EOC was investigated. A total of 66 patients treated by primary surgery were evaluated in this study. Immunohistochemical analysis for cyclin D1, pRb, p16, p53, p27(Kip1), p21(Waf1/Cip1) and cyclin E was performed on formalin-fixed tissue sections collected from primary surgical specimens. The correlations between the expression of these proteins and the clinicopathological parameters, including progression-free survival (PFS), overall survival (OS) and chemosensitivity, were examined. Upon univariate analysis, overexpression of cyclin D1 was positively correlated with reduced PFS (p=0.00062) and OS (p=0.00037). Reduced expression of p27(Kip1) was associated with shorter OS (p=0.064). Upon multivariate analysis, overexpression of cyclin D1 (p=0.0019), reduced expression of p27(Kip1) (p=0.042) and residual tumor volume (p=0.0092) were identified as independent predictors of OS. Overexpression of cyclin D1 (p=0.011) as well as residual tumor volume (p=0.006) were significantly associated with first-line chemosensitivity. In advanced serous EOC, overexpression of cyclin D1 contributed largely to poor prognosis, and this may have been in part mediated by chemoresistance. Cyclin D1 is a possible target for overcoming the refractory nature of advanced serous EOC.

Dentin sialophosphoprotein (DSPP) gene-silencing inhibits key tumorigenic activities in human oral cancer cell line, OSC2

Background

We determined recently that dentin sialophosphoprotein (DSPP), a member of the SIBLING (Small integrin-binding ligand N-linked glycoproteins) family of phosphoglycoproteins, is highly upregulated in human oral squamous cell carcinomas (OSCCs) where upregulation is associated with tumor aggressiveness. To investigate the effects of DSPP-silencing on the tumorigenic profiles of the oral cancer cell line, OSC2, short-hairpin RNA (shRNA) interference was employed to silence DSPP in OSC2 cells.

Methodology/Principal Findings

Multiple regions of DSPP transcript were targeted for shRNA interference using hDSP-shRNA lentiviral particles designed to silence DSPP gene expression. Control shRNA plasmid encoding a scrambled sequence incapable of degrading any known cellular mRNA was used for negative control. Following puromycin selection of stable lines of DSSP-silenced OSC2 cells, phenotypic hallmarks of oral carcinogenesis were assayed by western blot and RT-PCR analyses, MTT (cell-viability), colony-formation, modified Boyden-Chamber (migration and invasion), and flow cytometry (cell-cycle and apoptosis) analyses. DSPP-silenced OSC2 cells showed altered cell morphology, reduced viability, decreased colony-formation ability, decreased migration and invasion, G0/G1 cell-cycle arrest, and increased tumor cell sensitivity to cisplatin-induced apoptosis. Furthermore, MMP-2, MMP-3, MMP-9, VEGF, Ki-67, p53, and EGFR were down-regulated. There was a direct correlation between the degree of DSPP-silencing and MMP suppression, as indicated by least squares regression: MMP-2 {(y = 0.850x, p<0.001) (y = 1.156x, p<0.001)}, MMP-3 {(y = 0.994x, p<0.001) (y = 1.324x, p = 0.004)}, and MMP-9 {(y = 1.248x, p = 0.005, y = 0.809, p = 0.013)}.

Conclusions/Significance

DSPP-silencing in OSC2 cell decreased salient hallmarks of oral tumorigenesis and provides the first functional evidence of a potential key role for DSPP in oral cancer biology. The down-regulation of MMP-2, MMP-3, MMP-9, p53 and VEGF in DSPP-silenced OSC2 cells provides a significant functional/molecular framework for deciphering the mechanisms of DSPP activities in oral cancer biology.

Programmed cell death 4 enhances chemosensitivity of ovarian cancer cells by activating death receptor pathway in vitro and in vivo

Chemoresistance is a major cause of treatment failure in ovarian cancer. Therefore, it is necessary to explore alternative therapeutic methods to overcome drug resistance for ovarian cancer treatment. We previously reported that programmed cell death 4 (PDCD4), a tumor suppressor, significantly suppresses the malignant phenotype of ovarian cancer cells and its lost or low expression in ovarian cancer is associated with unfavorable prognosis of patients. Here we show that PDCD4 improves the sensitivity of ovarian cancer cells to platinum-based chemotherapy. Overexpression of PDCD4 enhanced chemosensitivity in SKOV3 and CAOV3 cells with low levels of PDCD4, whereas knockdown of PDCD4 reduced chemosensitivity in OVCAR3 cells with high levels of PDCD4. Subsequently, the combination of enforced PDCD4 expression with cisplatin treatment significantly suppressed ovarian tumor growth in a xenograft animal model. The PDCD4 effect appears to be specific for cisplatin and carboplatin, not affecting cyclophosphamide, etoposide, or paclitaxel. Mechanistically, PDCD4 significantly increased cisplatin-induced cleavage of caspase-3 and caspase-8, but had only a slight impact on caspase-9 cleavage and the expression of Bax and Bcl-2 in vitro and in vivo. A specific caspase-8 inhibitor, Z-ITED-FMK, attenuated cisplatin-induced apoptosis in PDCD4-overexpressing ovarian cancer cells. Taken together, our results indicate that PDCD4 enhances cisplatin-induced apoptosis by mainly activating the death receptor pathway, and PDCD4 gene transfer in combination with cisplatin therapy may break the resistance of ovarian cancer cells to chemotherapy.

The association of CCND1 overexpression and cisplatin resistance in testicular germ cell tumors and other cancers

Development of chemoresistance limits the clinical efficiency of platinum-based therapy. Although many resistance mechanisms have been demonstrated, genetic/molecular alterations responsible for drug resistance in the majority of clinical cases have not been identified. We analyzed three pairs of testicular germ cell tumor cell lines using Affymetrix expression microarrays and revealed a limited number of differentially expressed genes across the cell lines when comparing the parental and resistant cells. Among them, CCND1 was the most significantly differentially expressed gene. Analysis of testicular germ cell tumor clinical samples by quantitative reverse transcription PCR analysis revealed that overall expression of CCND1 was significantly higher in resistant cases compared with sensitive samples (P < 0.0001). We also found that CCND1 was dramatically overexpressed both in induced and intrinsically resistant samples of ovarian and prostate cancer. Finally combined CCND1 knockdown using small-interfering RNA and cisplatin treatment inhibited cell growth in vitro significantly more effectively than any of these single treatments. Therefore, deregulation of CCND1 may be a major cause of cisplatin resistance in testicular germ cell tumors and may also be implicated in ovarian and prostate cancers. CCND1 could be potentially used as a marker for treatment stratification and as a molecular target to improve the treatment of platinum-resistant tumors.

Detection of copy number amplification of cyclin D1 (CCND1) and cortactin (CTTN) in oral carcinoma and oral brushed samples from areca chewers

Oral squamous cell carcinoma (OSCC) in Asians is highly associated with the abuse of areca (betel) chewing. There are several hundred million Asians who chew areca and are therefore at high risk of OSCC. Aberrance in cyclin D1 (CCND1) and/or cortactin (CTTN), which are localized on 11q13, seems to be critical events for the development of oral carcinogenesis. This study identified amplifications of CCND1 and CTTN by quantitative (Q)-PCR analysis in 50% and 45% of OSCC samples, respectively. Co-amplification of both genes was identified in 20% of tumors. Higher CTTN expression was associated with nodal metastasis of the OSCC, while the amplification of CCND1 was identified in 28% of oral brushed samples from areca chewers, who form a high risk group for OSCC. This study confirms the importance of alterations in CCND1 and CTTN with respect to areca-associated OSCC, and demonstrates that there is an early occurrence of amplification of these genes in the risk population. The non-invasive brushing sampling method coupling with Q-PCR analysis needs to be validated for use as an early detection system for gene copy changes, which should aid oral cancer prevention.