Sinularin stabilizes FOXO3 protein to trigger prostate cancer cell intrinsic apoptosis.

Sinularin, a natural product that purified from soft coral, exhibits anti-tumor effects against various human cancers. However, the mechanisms are not well understood. In this study, we demonstrated that Sinularin inhibited the viability of human prostate cancer cells in a dose-dependent manner and displayed significant cytotoxicity only at high concentration against normal prostate epithelial cell RWPE-1. Flow cytometry assay demonstrated that Sinularin induced tumor cell apoptosis. Further investigations revealed that Sinularin exerted anti-tumor activity through intrinsic apoptotic pathway along with up-regulation of pro-apoptotic protein Bax and PUMA, inhibition of anti-apoptotic protein Bcl-2, mitochondrial membrane potential collapses, and release of mitochondrial proteins. Furthermore, we illustrated that Sinularin induced cell apoptosis via up-regulating PUMA through inhibition of FOXO3 degradation by the ubiquitin-proteasome pathway. To explore how Sinularin suppress FOXO3 ubiquitin-proteasome degradation, we tested two important protein kinases AKT and ERK that regulate FOXO3 stabilization. The results revealed that Sinularin stabilized and up-regulated FOXO3 via inhibition of AKT- and ERK1/2-mediated FOXO3 phosphorylation and subsequent ubiquitin-proteasome degradation. Our findings illustrated the potential mechanisms by which Sinularin induced cell apoptosis and Sinularin may be applied as a therapeutic agent for human prostate cancer.

DYRK1A reinforces epithelial-mesenchymal transition and metastasis of hepatocellular carcinoma via cooperatively activating STAT3 and SMAD.

BACKGROUND: Hepatocellular carcinoma (HCC) accounts for the majority of liver cancer cases, while metastasis is considered the leading cause of HCC-related death. However, the currently available treatment strategies for efficient suppression of metastasis are limited. Therefore, novel therapeutic targets to inhibit metastasis and effectively treat HCC are urgently required. METHODS: Wound healing and Transwell assays were used to determine the migration and invasion abilities of HCC cells in vitro. Quantitative real-time PCR (qRT-PCR), protein array, immunofluorescence, and immunoprecipitation experiments were used to study the mechanism of DYRK1A-mediated metastasis. A tail vein metastasis model and H&E staining were utilized to assess metastatic potential in vivo. RESULTS: The results of the current study demonstrated that dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) was upregulated in HCC tissues compared with normal liver tissues. Additionally, the level of DYRK1A was increased in primary HCC tissues of patients with metastasis compared with those of patients without metastasis, and DYRK1A overexpression correlated with worse outcomes in liver cancer patients. Gain- and loss-of-function studies suggested that DYRK1A enhanced the invasion and migration abilities of HCC cells by promoting epithelial-mesenchymal transition (EMT). Regarding the promoting effect of DYRK1A on cell invasion, the results showed that DYRK1A was coexpressed with TGF-ß/SMAD and STAT3 signalling components in clinical tumour samples obtained from patients with HCC. DYRK1A also activated TGF-ß/SMAD signalling by interacting with tuberous sclerosis 1 (TSC1) and enhanced metastasis of HCC cells by activating STAT3. Furthermore, DYRK1A promoted EMT by cooperatively activating STAT3/SMAD signalling. CONCLUSION: Overall, the present study not only uncovered the promoting effect of DYRK1A on HCC metastasis and revealed the mechanism but also provided a new approach to predict and treat metastatic HCC.

Enhanced anticancer activity by the combination of vinpocetine and sorafenib via PI3K/AKT/GSK-3ß signaling axis in hepatocellular carcinoma cells.

Vinpocetine is widely used to treat cerebrovascular diseases. However, the effect of vinpocetine to treat hepatocellular carcinoma (HCC) has not been investigated. In this study, we revealed that vinpocetine was associated with antiproliferative activity in HCC cells, but induced cytoprotective autophagy, which restricted its antitumor activity. Autophagy inhibitors improved the antiproliferative activity of vinpocetine in HCC cells. Sorafenib is effective to treat advanced HCC, but the effect of autophagy induced by sorafenib is indistinct. We demonstrated vinpocetine plus sorafenib suppressed the cytoprotective autophagy activated by vinpocetine in HCC cells and significantly induced apoptosis and suppressed cell proliferation in HCC cells. In addition, vinpocetine plus sorafenib activates glycogen synthase kinase 3ß (GSK-3ß) and subsequently inhibits cytoprotective autophagy induced by vinpocetine in HCC cells. Meanwhile, overexpression of GSK-3ß was efficient to increase the apoptosis induced by vinpocetine plus sorafenib in HCC cells. Our study revealed that vinpocetine plus sorafenib could suppress the cytoprotective autophagy induced by vinpocetine and subsequently show synergistically anti-HCC activity via activating GSK-3ß and the combination of vinpocetine and sorafenib might reverse sorafenib resistance via the PI3K/protein kinase B/GSK-3ß signaling axis. Thus, vinpocetine may be a potential candidate for sorafenib sensitization and HCC treatment, and our results may help to elucidate more effective therapeutic options for HCC patients with sorafenib resistance.

ApoC1 promotes the metastasis of clear cell renal cell carcinoma via activation of STAT3.

Clear cell renal cell carcinoma (ccRCC) is the most common renal cancer and frequently diagnosed at an advanced stage. It is prone to develop unpredictable metastases even with proper treatment. Antiangiogenic therapy is the most effective medical treatment for metastatic ccRCC. Thus, exploration of novel approaches to inhibit angiogenesis and metastasis may potentially lead to a better therapeutic option for ccRCC. Among all the types of cancer, renal cancer samples exhibited the maximum upregulation of ApoC1 as referred to in the Oncomine database. The expression of ApoC1 was increased accompanied by ccRCC progression. A high level of ApoC1 was closely related to poor survival time in ccRCC patients. Furthermore, ApoC1 was over-expressed in the highly invasive ccRCC cells as compared to that in the low-invasive ccRCC cells. Besides, ApoC1 promoted metastasis of ccRCC cells via EMT pathway, whereas depletion of ApoC1 alleviated these effects. ApoC1 as a novel pro-metastatic factor facilitates the activation of STAT3 and enhances the metastasis of ccRCC cells. Meanwhile, ApoC1 in the exosomes were transferred from the ccRCC cells to the vascular endothelial cells and promoted metastasis of the ccRCC cells via activating STAT3. Finally, the metastatic potential of the ccRCC cells driven by ApoC1 was suppressed by DPP-4 inhibition. Our study not only identifies a novel ApoC1-STAT3 pathway in ccRCC metastasis but also provides direction for the exploration of novel strategies to predict and treat metastatic ccRCC in the future.

A natural anthraquinone derivative shikonin synergizes with AZD9291 against wtEGFR NSCLC cells through reactive oxygen species-mediated endoplasmic reticulum stress.

BACKGROUND: NSCLC is the major type of lung cancer and the survival rates of NSCLC patients remain low. AZD9291 is a third-generation EGFR-TKI and approved to treat NSCLC patients harboring EGFR T790M mutation and common targetable activating EGFR mutations, but it has a limited effect for wtEGFR NSCLC. PURPOSE: The current study investigated whether shikonin could enhance the antitumor effect of AZD9291 in wtEGFR NSCLC cells. METHODS: SRB and colony formation assay were used to detect the proliferation of NSCLC cells, propidium iodide staining was performed to detect the apoptosis, ROS was analyzed using DCFH-DA staining, and western blot was used to detect the expression of indicated proteins. RESULTS: We demonstrated that shikonin, a natural ROS inducer, could enhance the antitumor effect of AZD9291 in wtEGFR NSCLC cells. In addition, shikonin increased AZD9291-induced apoptosis accompanying with the generation of ROS and activation of ER stress. Furthermore, ROS inhibition by NAC or GSH reversed the apoptosis induced by shikonin plus AZD9291, and recovered the ER stress activated by combination treatment, indicating that ROS mediated ER stress played a vital role in this combination therapy. Moreover, shikonin increased the anticancer activity of AZD9291 in primary wtEGFR NSCLC cells through ROS-mediated ER stress. CONCLUSION: Our study suggests that combining shikonin with AZD9291 is a promising therapeutic strategy for treating wtEGFR NSCLC patients.

Harmine suppresses the proliferation of pancreatic cancer cells and sensitizes pancreatic cancer to gemcitabine treatment.

PURPOSE: Pancreatic carcinoma is one of the most deadliest types of cancer, and relatively insensitive to the currently available chemotherapy. Thus, the discovery of novel therapeutic agents to prolong the survival times of patients with pancreatic cancer is urgently required. METHODS: Cell proliferation was assessed using the sulforhodamine B and cell clone formation assay, apoptosis was analyzed through Annexin V/PI staining, analysis of cell cycle distribution was determined by PI staining, and the expression of proteins was detected via Western blotting. RESULTS: Our data showed that harmine exerted an anti-proliferative effect and cell cycle arrest at G2/M in pancreatic cancer cells. Meanwhile, harmine plus gemcitabine showed strong synergy in inhibiting the proliferation of pancreatic cancer cells. Furthermore, harmine induced apoptosis and enhanced the gemcitabine-induced apoptosis in pancreatic cancer cells. The AKT/mTOR pathway is involved in mechanisms of gemcitabine resistance in pancreatic cancer cells, our data demonstrated that harmine plus gemcitabine significantly suppressed the AKT/mTOR signaling pathway. CONCLUSION: Harmine may be a potential candidate for the treatment of pancreatic cancer. Morever, the combination of harmine with gemcitabine appears to be an attractive option for the treatment of patients with pancreatic cancer.

Suppression of LSD1 enhances the cytotoxic and apoptotic effects of regorafenib in hepatocellular carcinoma cells.

Regorafenib has been approved to treat patients who have HCC progression after sorafenib failure, however, regorafenib also faces the risk of drug resistance and subsequent progression of HCC patients. As LSD1 inhibitors can alleviate acquired resistance to sorafenib, in this context, we are interested to investigate the role of LSD1 in regorafenib treatment. Firstly, over-expressed LSD1 was observed in HCC patients and predicted poor prognosis. However, regorafenib failed to suppress the expression of LSD1 in HCC cells. Thus, we hypothesized that LSD1 inhibition could enhance the anti-HCC activity of regorafenib. As expected, LSD1 knockdown could enhance anti-proliferation effect of regorafenib in HCC cells. LSD1 inhibitor SP2509 could enhance the cytotoxic and apoptotic effects of regorafenib in HCC cells. In addition, clinically used LSD1 inhibitor tranylcypromine also enhanced anti-HCC effect of regorafenib. Furthermore, LSD1 suppressed by SP2590 or tranylcypromine could alleviate the activated p-AKT (ser473) induced by regorafenib in HCC cells. Thus, inhibiting LSD1 might be an attractive target for regorafenib sensitization and clinical HCC therapy, our findings could help to elucidate more effective therapeutic options for HCC patients.

The anti-tumor effect of regorafenib in lung squamous cell carcinoma in vitro.

Lung squamous cell carcinoma (LSCC) is a common type of non-small-cell lung cancer (NSCLC) and lacks effective treatment. Regorafenib, an oral multikinase inhibitor, has demonstrated promising anti-tumor activity in various solid tumors. To study whether regorafenib inhibits LSCC cells, we investigate the compound in several LSCC cell lines and explore the possible mechanism. In this study, we confirmed that regorafenib had anti-proliferation effect on LSCC cell lines by inducing G0/G1 arrest. In addition, glycogen synthase kinase 3ß (GSK3ß) remained at the same level and Ser9 phosphorylation of GSK3ß decreased with increasing incubation time and increasing regorafenib concentration in LSCC cells. GSK3ß inhibition enhanced the anti-tumor activity of regorafenib. Thus, GSK3ß activation restricted the anti-cancer effect of regorafenib on LSCC. In conclusion, regorafenib might be a promising drug for LSCC therapy. GSK3ß might be a potential target to increase the anti-tumor effect of regorafenib in LSCC cells.