PRMT5 activates KLF5 by methylation to facilitate lung cancer.

The highly expressed oncogenic factor Krüppel-like factor 5 (KLF5) promotes various cancerous processes, such as cell growth, survival, anti-apoptosis, migration and metastasis, particularly in lung cancer. Nevertheless, the modifications to KLF5 after translation are poorly understood. Protein arginine methyltransferase 5 (PRMT5) is considered as an oncogene known to be involved in different types of carcinomas, including lung cancer. Here, we show that the expression levels of PRMT5 and KLF5 are highly expressed lung cancer. Moreover, PRMT5 interacts with KLF5 and facilitates the dimethylation of KLF5 at Arginine 41 in a manner that depends on methyltransferase activity. Downregulation or pharmaceutical suppression of PRMT5 reduces the expression of KLF5 and its downstream targets both in vitro and in vivo. Mechanistically, the dimethylation of KLF5 by PRMT5 promotes the maintenance and proliferation of lung cancer cells at least partially by stabilising KLF5 via regulation of the Akt/GSK3ß signalling axis. In summary, PRMT5 methylates KLF5 to prevent its degradation, thereby promoting the maintenance and proliferation of lung cancer cells. These results suggest that targeting PRMT5/KLF5 axis may offer a potential therapeutic strategy for lung cancer.

TIMP3 regulates osteosarcoma cell migration, invasion, and chemotherapeutic resistances.

Tissue inhibitors of metalloproteinases (TIMPs) inhibit matrix metalloproteinases (MMPs) to limit degradation of the extracellular matrix. Low levels of TIMP3 have been demonstrated in cancer tissues at advanced clinical stages, with positive distant metastasis and chemotherapeutic resistance. We examined the role of TIMP3 in osteosarcoma (OS) cell invasiveness and chemoresistance. TIMP3 was overexpressed or knocked down in the human OS cell lines Saos2 and MG63. Cell migration and invasion capacities were then evaluated using Transwell assays, and resistance to cisplatin was assessed by CCK-8 assay and flow cytometry. Real-time PCR and western blotting were used to investigate activation of signaling pathways downstream of TIMP3. Overexpression of TIMP3 inhibited the migration and invasion of Saos2 and MG63 cells, while knockdown of TIMP3 had the opposite effect. Cell survival after exposure to cisplatin was inhibited by TIMP3 overexpression in both Saos2 and MG63 cells. Consistently, downregulation of TIMP3 gene expression significantly decreased the sensitivity of OS cells to cisplatin treatment. MMP1, MMP2, Bcl-2, and Akt1 were all downregulated following TIMP3 overexpression, while Bax and cleaved caspase-3 were upregulated. TIMP3 knockdown had opposite effects on the regulation of these genes. Taken together, our findings suggest TIMP3 as a new target for inhibition of OS progression and chemotherapeutic resistance.

Smoking behavior associated upregulation of SERPINB12 promotes proliferation and metastasis via activating WNT signaling in NSCLC.

BACKGROUND: Non-small cell lung cancer (NSCLC) is the leading cause of morality among all malignant tumors. Smoking is one of the most important causes of NSCLC, which contributes not only to the initiation of NSCLC but also to its progression. The identification of specific biomarkers associated with smoking will promote diagnosis and treatment. METHODS: Data mining was used to identify the smoking associated gene SERPINB12. CCK8 assays, colony formation assays, a mouse xenograft model and transwell assays were performed to measure the biological functions of SERPINB12 in NSCLC. GSEA, luciferase reporter assays and immunofluorescence were conducted to explore the potential molecular mechanisms of SERPINB12 in NSCLC. RESULTS: In this study, by data mining the TCGA database, we found that SERPINB12 was greatly upregulated in NSCLC patients with cigarette consumption behavior, while the expression level was positively correlated with disease grade and poor prognosis. SERPINB12 is a kind of serpin peptidase inhibitor, but its function in malignant tumors remains largely unknown. Functionally, knockdown of SERPINB12 observably inhibited the proliferation and metastasis of NSCLC cells in vitro and in vivo. Moreover, downregulation of SERPINB12 attenuated Wnt signaling by inhibiting the nuclear translocation of ß-catenin, which explained the molecular mechanism underlying tumor progression. CONCLUSIONS: In conclusion, SERPINB12 functions as a tumorigenesis factor, which could be a promising biomarker for NSCLC patients with smoking behavior, as well as a therapeutic target.

Strontium-incorporated mineralized PLLA nanofibrous membranes for promoting bone defect repair.

Mineralized scaffolds, which are fabricated by electrodeposition, mimic the chemistry of natural bone and have attracted a great amount of attention due to their rapid and simple production. In this study, mineralized electrospun polylactic acid (PLLA) nanofibrous membranes containing different amounts of strontium (Sr) were fabricated by an electrodeposition method for potential use in bone regeneration applications. In vitro assays, including cell proliferation and osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs) grown on these membranes and in vivo cranial bone defect repair assays, were carried out. It was found that mineral crystals could be uniformly deposited onto the electrospun nanofibrous membranes, while the morphologies of the formed crystals were affected by the amount of Sr. By analysis of the X-ray diffraction (XRD) measurements, the formed crystalline phase was dramatically affected by the incorporation of Sr, which drove a conversion from the hydroxyapatite (HA) phase to the dicalcium phosphate dehydrate (DCPD) phase. The release of Sr2+ from the Sr/PLLA nanofibrous membranes was monitored over 20 d, and the release rates of Ca2+ and PO43- from the Sr-incorporated samples were higher compared with those of the mineralized sample without Sr. In vitro cell proliferation experiments demonstrated that mineralized Sr/PLLA nanofibrous membranes could facilitate BMSC proliferation. Furthermore, the mineralized Sr/PLLA nanofibrous membranes induced a higher degree of osteogenic differentiation in the BMSCs compared with those of pure PLLA and mineralized PLLA, as determined by the results of alkaline phosphatase (ALP) activity, alizarin red (AR) and osteocalcin (OCN) staining and the expression of osteogenesis-related genes. More importantly, in vivo cranial defect experiments revealed that mineralized Sr/PLLA nanofibrous membranes promoted bone regeneration. These findings indicated that mineralized Sr/PLLA nanofibrous membranes are a promising material for bone tissue engineering.

TIMP3 Overexpression Improves the Sensitivity of Osteosarcoma to Cisplatin by Reducing IL-6 Production.

Osteosarcoma is the most common bone cancer in children and adolescents. Tissue inhibitors of metalloproteinases (TIMPs)-3 inhibit matrix metalloproteinases to limit extracellular matrix degradation. Cisplatin is a widely used chemotherapeutic drug used to cure osteosarcoma. Interleukin (IL)-6 and TIMP3 play important roles in the drug resistance of osteosarcoma; however, their relationship in this process remains unclear. This study aimed to explore the role of TIMP3 in the cisplatin sensitivity of osteosarcoma and its underlying molecular mechanisms in vitro and in vivo. We compared TIMP3 expression levels between patients with cisplatin-sensitive and -insensitive osteosarcoma. TIMP3 was overexpressed or knocked down in the Saos2-lung cell line, which is a Saos2 subtype isolated from pulmonary metastases that has higher cisplatin chemoresistance than Saos2 cells. IL-6 expression, cell proliferation, sensitivity to cisplatin, migration, and invasion after TIMP3 overexpression or knockdown were determined. The same experiments were performed using MG63 and U2OS cells. Subsequently, luciferase-labeled Saos2-lung cells overexpressing TIMP3 were injected into the tibiae of nude mice treated with cisplatin. The results showed that IL-6 inhibited TIMP3 expression in Saos2 and Saos2-lung cells via signal transducer and activator of transcription 3 (STAT3) activation. STAT3 knockdown reversed the effect of IL-6. The expression of TIMP3 was higher in patients with cisplatin-sensitive osteosarcoma than in those with insensitive osteosarcoma. IL-6 expression was downregulated upon TIMP3 overexpression, and upregulated by TIMP3 knockdown. TIMP3 overexpression suppressed cell proliferation and enhanced cisplatin sensitivity by activating apoptosis-related signal pathways and inhibiting IL-6 expression in vitro and in vivo. In conclusion, cisplatin sensitivity correlated positively with TIMP3 expression, which is regulated by the IL-6/TIMP3/caspase pathway. The TIMP3 pathway could represent a target for new therapies to treat osteosarcoma.

Dihydroartemisinin-induced apoptosis in human acute monocytic leukemia cells.

Dihydroartemisinin (DHA) is a derivative of artemisinin. The present study aimed to investigate whether DHA induces apoptosis in the THP-1 human acute monocytic leukemia cell line (AMoL), and to identify the relative molecular mechanisms. The results of the present study demonstrated that the viability of THP-1 cells were inhibited by DHA in a dose- and time-dependent manner, which was accompanied by morphological characteristics associated with apoptosis. After 24 h of 200 µM DHA treatment, the proportion of apoptotic cells was significantly increased compared with the untreated controls (P<0.01). In addition, DHA downregulated the levels of B-cell lymphoma (Bcl)-2, protein kinase B (Akt)1, Akt2 and Akt3 gene expression, and increased the expression of the Bcl-2-associated X protein apoptosis regulator. The protein expression of phospho-Akt and phospho-extracellular signal-regulated kinase (ERK) was also decreased, and the protein expression level of cleaved caspase-3 was increased following treatment with DHA. Therefore, DHA may induce apoptosis in the AMoL THP-1 cell line via currently unknown underlying molecular mechanisms, including the downregulation of ERK and Akt, and the activation of caspase-3.

Cordycepin induces apoptosis of human acute monocytic leukemia cells via downregulation of the ERK/Akt signaling pathway.

The aim of the present study was to examine the apoptotic effect of cordycepin (COR) on human THP-1 acute monocytic leukemia cells. THP-1 cells were exposed to different concentrations of COR for 24, 48, 72 or 96 h. The cell viability and apoptotic rate were analyzed. The gene expression of Akt1, Akt2, Akt3, B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) were assessed by reverse-transcription quantitative PCR. Western blot analysis was used to detect the protein levels of phosphorylated (p)-Akt, p-extracellular signal-regulated kinase (ERK) and cleaved caspase-3. It was found that the viability of THP-1 cells was inhibited by COR in a dose- and time-dependent manner. After treatment with 200 µM COR for 24 h, the percentage of apoptotic cells was significantly increased. COR also downregulated the levels of Bcl-2, Akt1, Akt2 and Akt3, and elevated the expression of Bax. The protein levels of p-Akt and p-ERK were suppressed and cleaved caspase-3 was increased after treatment of COR. In conclusion, COR was found to induce apoptosis of THP-1 acute monocytic leukemia cells through downregulation of ERK/Akt signaling.