Genetic association between cyclin D1 polymorphism and breast cancer susceptibility

The critical role of SETDB1-mediated CCND1/PI3K/AKT pathway via p53-RS di-methylation at K370 in the proliferation of WRL68 cells induced by nicotine

Constituents of cigarette smoke are known to be carcinogens. Additionally, there is mounting evidence that the liver is an organ susceptible to tobacco carcinogenicity. Nicotine, the primary constituent of tobacco, plays a role in cancer progression. In our previous study, it was found that nicotine enhances the proliferation of a human normal fetal hepatic (WRL68) cell due to the activation of p53 mutation at Ser249 (p53-RS)/STAT1/CCND1 signaling pathway. Here, we further elucidated the mechanism of regulating this pathway. Firstly, dose-dependent increase of SETDB1 protein level in WRL68 cells upon exposure to nicotine (1.25, 2.5, and 5 μM), significantly enhanced cellular proliferation. In addition, the upregulation of SETDB1 protein was necessary for the nuclear translocation of p53-RS to establish a ternary complex with STAT1 and SETDB1, which facilitated p53-RS di-methylation at K370 (p53-RS/K370me2). After that, the activation of CCND1/PI3K/AKT pathway was initiated when STAT1 stability was enhanced by p53-RS/K370me2, ultimately resulting in cell proliferation. Altogether, the study revealed that the increase in SETDB1 expression could potentially have a significant impact on the activation of CCND1/PI3K/AKT pathway through p53-RS/K370me2, leading to the proliferation of WRL68 cells induced by nicotine, which could contribute to hepatocellular carcinoma for smokers. Besides, the results of this study provided a foundation for the development of anticancer therapies for cancers associated with tobacco use.

Dlx5 promotes cancer progression through regulation of CCND1 in oral squamous cell carcinoma (OSCC)

Genetic studies have revealed a critical role of the distal-less homeobox gene 5 (Dlx5) in the pathogenesis of ovarian cancer, lung cancer, and T-cell lymphoma; however, the role and underlying mechanisms of Dlx5 in oral squamous cell carcinoma (OSCC) are largely unknown. In this study, we demonstrated that Dlx5 is up-regulated in OSCC tissues and cell lines, compared with their control groups. The results from our immunohistochemistry (IHC) analyses show that high expression levels of Dlx5 correlated with advanced TNM stages (P = 0.0001), lymph node metastasis (P = 0.0049), poor cellular differentiation (P = 0.0491), location of the tumors (P = 0.0132), and poor prognosis for the patient. We also demonstrated that knockdown of Dlx5 inhibited the viability, proliferation, and colony formation of OSCC cell lines CAL-27 and WSU-HN6 cells, probably by blocking cell cycle in the G1 phase. Furthermore, we revealed that Dlx5 exerts its biological functions via direct regulation of CCND1 in CAL-27 and WSU-HN6 cells. Ultimately, we have demonstrated that silencing of Dlx5 inhibits the growth of xenograft tumors in vivo, and that Dlx5 affects the progression of OSCC both in vitro and in vivo via directly regulating CCND1, providing a potential diagnostic biomarker and therapeutic target for OSCC.

Downregulation of lncRNA ZFAS1 inhibits the hallmarks of thyroid carcinoma via the regulation of miR‑302‑3p on cyclin D1

At present, treatment options for thyroid carcinoma remain limited. The present study aimed to investigate the role of ZFAS1 in various major hallmarks of cancer and the underlying mechanisms in thyroid carcinoma cells. The interactions between long non‑coding RNAs (lncRNAs), microRNAs (miRs) and target genes were predicted by bioinformatics and confirmed by performing dual‑luciferase assays. The mRNA and protein expressions were determined by reverse transcription‑quantitative PCR and western blotting. Cell invasion, migration, and viability were evaluated via Transwell, wound‑healing and Cell Counting Kit‑8 assays, respectively. The results demonstrated that lncRNA ZFAS1 expression was upregulated in thyroid carcinoma tissues, TT and SW579 cells, and was associated with the proliferation of these two cell lines. Notably, downregulation ZFAS1 reduced migration and invasion, and reversed the promotive effects of miR‑302a‑3p inhibitor on the proliferation, migration and invasion of TT and SW579 cells. Moreover, cyclin D1 (CCND1) is targeted by miR‑302a‑3p, and was regulated by ZFAS1. In addition, the downregulation of ZFAS1 not only reversed the promotive effects of miR‑302a‑3p inhibitor on CCND1 expression and the epithelial‑mesenchymal transition (EMT) of TT and SW579 cells, but also targeted and increased the expression of miR‑302a‑3p, and further reduced the expression of CCND1, resulting in suppression of the proliferation, migration, invasion and EMT of thyroid carcinoma cells.

Meningioma Tumor Microenvironment

The tumor microenvironment consists of noncancerous cells, such as immune cells and fibroblasts, and the proteins produced by these cells as well as the extracellular matrix components in the environment around a tumor. Tumor influences the behavior of the cells present in the surrounding environment, while the cells in the tumor microenvironment modulate the evolution of the tumor. Little is known about the microenvironment of meningioma, the most common benign intracranial tumor. Here, we review the current knowledge of the tumor microenvironment of meningioma and discusses its importance in meningioma tumorigenesis as well as in the designation of novel therapeutic approaches.

Effect of down-regulation of miR-221 on cell proliferation and cisplatin sensitivity in cisplatin-resistant gastric cancer cells and underlying mechanism

BACKGROUND

Patients with advanced gastric cancer (GC) usually undergo chemotherapy as the primary treatment. However, the effectiveness of chemotherapy is often limited by the development of drug resistance in GC cells. This study aimed to investigate the expression pattern, biological role, and potential mechanism of microRNA-221 (miR-221) in cisplatin (DDP)-resistant GC cells, in order to provide a reference for clinical treatment of this malignancy.

AIM

To investigate the effect of down-regulation of miR-221 on cell proliferation and DDP sensitivity in DDP-resistant GC cells and to explore the underlying mechanism.

METHODS

AGS and MGC-803 cells were screened for DDP-resistant cells (AGS/DDP and MGC-803/DDP). The expression levels of miR-221 in GC tissues, matched tumor adjacent tissues, DDP-sensitive tissues, DDP-resistant tissues, GC cells, and DDP-resistant GC cells were detected by RT-PCR. After AGS/DDP and MGC-803/DDP cells were transfected with LV-miR-221-shRNA, cell proliferation and DDP sensitivity in those cells were measured by MTT assay, cell apoptosis was detected by Annexin V-FITC/PI staining, and the mRNA and protein expression of CCND1 was detected by RT-qPCR and Western blot, respectively. The potential target genes of miR-221 were predicted by bioinformatics analysis.

RESULTS

The expression of miR-221 was up-regulated in GC tissues and gastric cells, especially in DDP-resistant tissues and DDP-resistant GC cells. Down-regulation of miR-221 inhibited the proliferation of AGS/DDP and MGC-803/DDP cells, but increased their apoptosis and chemosensitivity to DDP. CCND1 was found to be a direct target gene of miR-221. Transfection with LV-miR-221-shRNA inhibited the mRNA and protein expression of CCND1.

CONCLUSION

Down-regulation of miR-221 can inhibit cell proliferation and promote chemosensitivity to DDP in DDP-resistant GC cells, which may be achieved by inhibiting the expression of its target gene CCND1.

MicroRNA-623 Targets Cyclin D1 to Inhibit Cell Proliferation and Enhance the Chemosensitivity of Cells to 5-Fluorouracil in Gastric Cancer

The dysregulation of microRNAs (miRNAs) plays an important function in the onset and progression of gastric cancer (GC). In addition, aberrantly expressed miRNAs affect the chemosensitivity of GC cells to chemotherapeutic drugs. Hence, miRNA-based targeted therapy might be applied to treat patients with GC exhibiting chemotherapeutic resistance. In this study, miRNA-623 (miR-623) expression was downregulated in GC tissues and cell lines. Functional analysis showed that the restored miR-623 expression could inhibit the proliferation of GC cells and enhance their chemosensitivity to 5-FU via the cell apoptosis pathway. Cyclin D1 (CCND1) was identified as a direct target gene of miR-623 in GC. The overexpressed CCND1 in GC tissues was negatively correlated with miR-623 level. The recovered CCND1 expression counteracted the effects of miR-623 on GC cell proliferation, chemosensitivity, and 5-FU-induced apoptosis. Thus, our results suggest that miR-623 might function as a tumor suppressor in GC and could be a promising therapeutic target for patients with GC, especially those with chemotherapeutic resistance.

microRNA-374a suppresses colon cancer progression by directly reducing CCND1 to inactivate the PI3K/AKT pathway

microRNA-374a (miR-374a) exhibits oncogenic functions in various tumor types. Here we report that miR-374a suppresses proliferation, invasion, migration and intrahepatic metastasis in colon adenocarcinoma cell lines HCT116 and SW620. Notably, we detected that PI3K/AKT signaling and its downstream cell cycle factors including c-Myc, cyclin D1 (CCND1), CDK4 and epithelial-mesenchymal transition (EMT)-related genes including ZEB1, N-cadherin, Vimentin, Slug, and Snail were all significantly downregulated after miR-374a overexpression. Conversely, cell cycle inhibitors p21 and p27 were upregulated. Expression of E-cadherin was only decreased in HCT116, without any obvious differences observed in SW620 cells. Furthermore, luciferase reporter assays confirmed that miR-374a could directly reduce CCND1. Interestingly, when CCND1 was silenced or overexpressed, levels of pPI3K, pAkt as well as cell cycle and EMT genes were respectively downregulated or upregulated. We examined miR-374a levels by in situ hybridization and its correlation with CCND1 expression in CRC tumor tissues. High miR-374a expression with low level of CCND1 was protective factor in CRC. Together these findings indicate that miR-374a inactivates the PI3K/AKT axis by inhibiting CCND1, suppressing of colon cancer progression.

Downregulation of miR-503 Promotes ESCC Cell Proliferation, Migration, and Invasion by Targeting Cyclin D1

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive cancers in China, but the underlying molecular mechanism of ESCC is still unclear. Involvement of microRNAs has been demonstrated in cancer initiation and progression. Despite the reported function of miR-503 in several human cancers, its detailed anti-oncogenic role and clinical significance in ESCC remain undefined. In this study, we examined miR-503 expression by qPCR and found the downregulation of miR-503 expression in ESCC tissue relative to adjacent normal tissues. Further investigation in the effect of miR-503 on ESCC cell proliferation, migration, and invasion showed that enhanced expression of miR-503 inhibited ESCC aggressive phenotype and overexpression of CCND1 reversed the effect of miR-503-mediated ESCC cell aggressive phenotype. Our study further identified CCND1 as the target gene of miR-503. Thus, miR-503 functions as a tumor suppressor and has an important role in ESCC by targeting CCND1.