Serotonin/HTR1E signaling blocks chronic stress-promoted progression of ovarian cancer.

Rationale: Psychological stress has been linked to cancer development and resistance to therapy by many epidemiological and clinical studies. Stress-induced immunosuppressive microenvironment by stress hormones, in particular glucocorticoids, has been extensively studied. However, the impacts of other stress-related neurotransmitters, such as serotonin (5-hydroxytryptamine, 5-HT), on cancer development just start to be revealed. Here, we aimed to identify novel neurotransmitters involved in stress-induced growth and dissemination of ovarian cancer (OC) and reveal the major underlying signaling pathway and the therapeutic significance. Methods: Through a genome-wide CRISPR/Cas9 knockout screen in the murine orthotopic model of ovarian carcinoma (OC), we identified candidate genes regulating the peritoneal dissemination of OC. Among them, we picked out HTR1E, one member of 5-HT receptor family specifically expressed in the ovary and endometrium in addition to brain. The correlation of HTR1E expression with OC progression was analyzed in OC patient specimen by quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blot, and immunohistochemistry (IHC). Gain-of-function and loss-of-function analyses were performed to explore the functions of 5-HT/HTR1E signaling in OC growth and dissemination in vitro and in vivo. In addition, we investigated the therapeutic values of HTR1E specific agonist and small molecular inhibitors against HTR1E downstream factor SRC in a stressed murine OC xenograft model. Results: In OC patients, the HTR1E expression is dramatically decreased in peritoneal disseminated OC cells, which correlates with poor clinical outcome. Silence of HTR1E in OC cells greatly promotes cell proliferation and epithelial mesenchymal transition (EMT) by the activation of SRC-mediated downstream signaling pathways. Furthermore, chronic stress results in significantly decreased serotonin in the ovary and the enhanced OC growth and peritoneal dissemination in mice, which can be strongly inhibited by specific HTR1E agonist or the SRC inhibitor. Conclusions: We discovered the essential role of serotonin/HTR1E signaling in preventing the chronic psychological stress-promoted progression of OC, suggesting the potential therapeutic value of the HTR1E specific agonist and the SRC inhibitor for OC patients who are suffering from psychological stress.

Overexpression of microRNA-9 enhances cisplatin sensitivity in hepatocellular carcinoma by regulating EIF5A2-mediated epithelial-mesenchymal transition.

We investigated the role of microRNA (miR)-9 in modulating chemoresistance in hepatocellular carcinoma (HCC) cells. MiR-9 was overexpressed or knocked down in HCC cell lines. Cell viability, cell proliferation, the expression of EIF5A2 and the epithelial-mesenchymal transition (EMT)-related proteins were examined. HCC cells overexpressing miR-9 were more sensitive to cisplatin; miR-9 knockdown yielded the opposite result. The in vivo nude mouse HCC xenograft tumors yielded the same results. EIF5A2 was identified as a potential target of miR-9, where miR-9 regulated EIF5A2 expression at mRNA and protein level. EIF5A2 knockdown reversed miR-9 inhibition-mediated cisplatin resistance. Altering miR-9 and EIF5A2 expression changed E-cadherin and vimentin expression. Furthermore, EIF5A2 mediated miR-9 EMT pathway regulation, indicating that miR-9 can enhance cisplatin sensitivity by targeting EIF5A2 and inhibiting the EMT pathway. Targeting miR-9 may be useful for overcoming drug resistance in HCC.

Curcumin Inhibits the Proliferation, Migration, Invasion, and Apoptosis of Diffuse Large B-Cell Lymphoma Cell Line by Regulating MiR-21/VHL Axis.

PURPOSE: Curcumin exerts its anti-cancer effects, partly by targeting special microRNAs, in human cancers. MiR-21 is a key oncomir in carcinogenesis of multiple human cancers. Here, we aimed to further explore the mechanistic insight into the link between curcumin and miR-21 on diffuse large B-cell lymphoma (DLBCL). MATERIALS AND METHODS: Quantitative real-time PCR assays were performed to assess the levels of miR-21 and Von Hippel-Lindau (VHL) mRNA. In situ hybridization assay was used for miR-21 expression visualization in lymphoma tissues. Western blot was used for determination of VHL protein, Ki-67, caspase-3, and cleaved caspase-3 levels. Dual-luciferase reporter assay and RNA immunoprecipitation assay were employed to confirm the direct target of miR-21. MTT assay, flow cytometric analysis, and transwell assay were used to evaluate cell proliferation, apoptosis, and migration and invasion capacities, respectively. RESULTS: Curcumin repressed the proliferation, migration, and invasion abilities and promoted apoptosis in SU-DHL-8 cells. Curcumin inhibited miR-21 expression and curcumin exerted its anti-proliferation, anti-migration, anti-invasion, and pro-apoptosis effects by miR-21 in SU-DHL-8 cells. VHL was a direct target of miR-21. Moreover, curcumin exerted its regulatory effects on SU-DHL-8 cells by VHL. CONCLUSION: Curcumin exerted its anti-proliferation, anti-migration, anti-invasion, and pro-apoptosis functions, at least partly, by repressing miR-21 and regulating VHL expression in DLBCL cell line. Our findings provided a possible molecular mechanism of curcumin-mediated anti-cancer effect.

Upregulation of MLK4 promotes migratory and invasive potential of breast cancer cells.

Metastasis to distant organs is a major cause for solid cancer mortality, and the acquisition of migratory and invasive phenotype is a key factor in initiation of malignancy. In this study we investigated the contribution of Mixed-Lineage Kinase 4 (MLK4) to aggressive phenotype of breast cancer cells. Our TCGA cancer genomic data analysis revealed that amplification or mRNA upregulation of MLK4 occurred in 23% of invasive breast carcinoma cases. To find the association between MLK4 expression and the specific subtype of breast cancer, we performed a transcriptomic analysis of multiple datasets, which showed that MLK4 is highly expressed in triple-negative breast cancer compared to other molecular subtypes. Depletion of MLK4 in cell lines with high MLK4 expression impaired proliferation and anchorage-dependent colony formation. Moreover, silencing of MLK4 expression significantly reduced the migratory potential and invasiveness of breast cancer cells as well as the number of spheroids formed in 3D cultures. These in vitro findings translate into slower rate of tumor growth in mice upon MLK4 knock-down. Furthermore, we established that MLK4 activates NF-κB signaling and promotes a mesenchymal phenotype in breast cancer cells. Immunohistochemical staining of samples obtained from breast cancer patients revealed a strong positive correlation between high expression of MLK4 and metastatic potential of tumors, which was predominantly observed in TNBC subgroup. Taken together, our results show that high expression of MLK4 promotes migratory and invasive phenotype of breast cancer and may represent a novel target for anticancer treatment.

The Effect of EPO Gene Overexpression on Proliferation and Migration of Mouse Bone Marrow-Derived Mesenchymal Stem Cells.

The aim of this study is to investigate the effect of erythropoietin (EPO) gene overexpression on proliferation and migration of mouse bone marrow-derived mesenchymal stem cells (MSCs), and to determine the underlying signaling pathway. Mouse MSCs were cultured in vitro and EPO gene was transfected into the 6th generation of MSCs via lentivirus vector. The transfected cells were identified by flow cytometry and the EPO levels in supernatant were measured with ELISA. In addition, cell proliferation was assessed by CCK-8 assay and cell migration was evaluated by Transwell assay. The activation of Akt, ERK1/2, and p38MAPK signaling was detected by western blotting. The lentivirus vector containing EPO was successfully constructed and transfected into MSCs. No remarkable change was found in the cell surface markers after transfection while a significant increase of EPO level in supernatant was noticed in transfected MSCs compared to controls (P < 0.01). In addition, transfected MSCs showed a significantly enhanced proliferation (P < 0.01) as well as a notable increase in migration (P < 0.01) compared to controls. Furthermore, we also found that EPO modification enhanced the phosphorylation of PI3K/Akt and ERK signaling pathway, and suppressed the phosphorylation of p38MAPK without affecting the levels of total Akt, ERK1/2, and p38MAPK in MSCs. After transfection, MSCs secreted more EPO which enhanced the capability of proliferation and migration. Moreover, our results suggested that the enhanced proliferation and migration might be associated with activation of PI3K/Akt and ERK or inhibition of P38MAPK signaling pathway.

The interaction of the second Kunitz-type domain (KD2) of TFPI-2 with a novel interaction partner, prosaposin, mediates the inhibition of the invasion and migration of human fibrosarcoma cells.

TFPI-2 (tissue factor pathway inhibitor-2) has recently been recognized as a new tumour suppressor gene. Low expression of this protein in several types of cancers allows for enhanced tumour growth, invasion and metastasis. To investigate the molecular mechanism responsible for the tumour-suppressor effects of TFPI-2, we performed yeast two-hybrid analysis and identified PSAP (prosaposin) as a TFPI-2-interacting partner. This interaction was confirmed by co-immunoprecipitation and immunofluorescence. The region of TFPI-2 that interacts with PSAP is located in the KD2 (Kunitz-type domain 2). Further study showed that PSAP does not affect the function of TFPI-2 as a serine proteinase inhibitor, but that TFPI-2 could inhibit the invasion-promoting effects of PSAP in human HT1080 fibrosarcoma cells. The results of the present study revealed that TFPI-2 interacts with PSAP, which may play an important role in the physiology and pathology of diseases such as cancer.