OVOL2 inhibits macrophage M2 polarization by regulating IL-10 transcription, and thus inhibits the tumor metastasis by modulating the tumor microenvironment.

Invasion and metastasis of breast cancer cells is an important cause of death in breast cancer patients. In the tumor microenvironment, M2 polarization of macrophages can promote the invasion and metastasis of tumor cells. OVOL2 is an evolutionarily conserved transcription regulator, but its effect in macrophages has not been described previously. The aim of this study was to investigate the effects of OVOL2 on macrophage polarity and the role of these effects in the tumor metastasis. We found that overexpression of OVOL2 in macrophages significantly inhibited M2 polarization and thus inhibits breast cancer metastasis. We propose a novel mechanism in which OVOL2 inhibits M2 polarization of macrophages and thus reduces their ability to induce invasion and metastasis of breast cancer. By shedding new light on the regulation of metastasis in cancers, our study provides a new strategy for the targeted therapy of cancer.

pH-Sensitive Black Phosphorous-Incorporated Hydrogel as Novel Implant for Cancer Treatment.

In this study, black phosphorus nanosheets (BPNSs) were incorporated into a hydrogel formed from dibenzaldehyde-functionalized polymer (DF-PEG) and polyaspartylhydrazide (PAHy) polymer to create an injectable and pH-sensitive DF-PEG-PAHy/BPNSs hydrogel, which can be used as a smart depot for synergistic chemo-photothermal cancer therapy. The DF-PEG-PAHy/BPNSs hydrogel exhibited excellent gelation characteristics, pH sensitivity, and near-infrared responsiveness. The nanocomposite hydrogel provided controlled drug release and near-infrared irradiation speeded up release of drug from the hydrogel because of the photothermal effect of the BPNSs. Cytotoxicity tests confirmed that the hydrogel has good biocompatibility and exerts its photothermal effect in vitro. Antitumor tests in mice demonstrated the capacity of DF-PEG-PAHy/BPNSs hydrogel for synergistic chemo-photothermal therapy in vivo. The hydrogel showed reduced adverse effects because of stable drug release in the tumor area and an efficient photothermal effect. Together, these data demonstrated the potential of DF-PEG-PAHy/BPNSs hydrogel containing a chemotherapy drug to serve as a novel smart delivery system for combined chemo-photothermal cancer therapy.

OVOL2 antagonizes TGF-ß signaling to regulate epithelial to mesenchymal transition during mammary tumor metastasis.

Great progress has been achieved in the study of the role of TGF-ß signaling in triggering epithelial-mesenchymal transition (EMT) in a variety of cancers; however, the regulation of TGF-ß signaling during EMT in mammary tumor metastasis has not been completely defined. In the present study, we demonstrated that OVOL2, a zinc finger transcription factor, inhibits TGF-ß signaling-induced EMT in mouse and human mammary tumor cells, as well as in mouse tumor models. Data from the Oncomine databases indicated a strong negative relationship between OVOL2 expression and breast cancer progression. Moreover, our experiments revealed that OVOL2 inhibits TGF-ß signaling at multiple levels, including inhibiting Smad4 mRNA expression and inducing Smad7 mRNA expression, blocking the binding between Smad4 and target DNA, and interfering with complex formation between Smad4 and Smad2/3. These findings reveal a novel mechanism that controls the TGF-ß signaling output level in vitro and in vivo. The modulation of these molecular processes may represent a strategy for inhibiting breast cancer invasion by restoring OVOL2 expression.

Ovol2 gene inhibits the Epithelial-to-Mesenchymal Transition in lung adenocarcinoma by transcriptionally repressing Twist1.

BACKGROUND: Associated with recent achievements in therapy for advanced lung adenocarcinoma, there will still be an unmet medical need for effective treatment of stage IIIb/IV, and the prognosis of lung cancer is not optimistic till now. OBJECTIVE: In order to obtain some essential evidences for a potential targeted therapy in lung adenocarcinoma, the effects of Ovol2 gene on Epithelial-to-Mesenchymal Transition (EMT) was observed and the probable mechanisms were analyzed. METHODS: Ovol2 expression was previously evaluated by immunochemistry in lung adenocarcinoma tissue, and Ovol2 was overexpressed by lentivirus infection in A549 cells. Subsequently, the migration and invasion ability of A549 cells was tested by Transwell and Wound healing experiments. The mRNA level of genes correlated to EMT was detected by Real-time PCR, and the expression of reasonable makers was probed by Western Blot. Finally, rescue experiment, Luciferase assay, and chromatin immunoprecipitation assay were performed to explore the probable mechanisms. RESULTS: After treated with Ovol2 overexpression, the expression level of E-cadherin was increased, while the expression level of Vimentin and Twist1 was declined not only in the mRNA level but also in the protein level. Moreover, we found that Ovol2 represses transcription of Twist1 by binding to its promoter directly. Wound healing and Transwell assays indicate that the migration and invasion ability were downregulated by Ovol2 in A549 cells. CONCLUSION: Ovol2 can suppress migration and invasion ability of A549 cells, and prevent EMT by inhibition of Twist1 transcription directly.

OVOL2, an Inhibitor of WNT Signaling, Reduces Invasive Activities of Human and Mouse Cancer Cells and Is Down-regulated in Human Colorectal Tumors.

BACKGROUND & AIMS: Activation of WNT signaling promotes the invasive activities of several types of cancer cells, but it is not clear if it regulates the same processes in colorectal cancer (CRC) cells, or what mechanisms are involved. We studied the expression and function of OVOL2, a member of the Ovo family of conserved zinc-finger transcription factors regulated by the WNT signaling pathway, in intestinal tumors of mice and human beings. METHODS: We analyzed the expression of OVOL2 protein and messenger RNA in CRC cell lines and tissue arrays, as well as CRC samples from patients who underwent surgery at Xiamen University in China from 2009 to 2012; clinical information also was collected. CRC cell lines (SW620) were infected with lentivirus expressing OVOL2, analyzed in migration and invasion assays, and injected into nude mice to assess tumor growth and metastasis. Tandem affinity purification was used to purify the OVOL2-containing complex from CRC cells; the complex was analyzed by liquid chromatography, tandem mass spectrometry, and immunoprecipitation experiments. Gene promoter activities were measured in luciferase reporter assays. We analyzed mice with an intestine-specific disruption of Ovol2 (Ovol2(flox/+) transgenic mice), as well as Apc(min/+) mice; these mice were crossed and analyzed. RESULTS: Analysis of data from patients indicated that the levels of OVOL2 messenger RNA were significantly lower in colon carcinomas than adenomas, and decreased significantly as carcinomas progressed from grades 2 to 4. Immunohistochemical analysis of a tissue array of 275 CRC samples showed a negative association between tumor stage and OVOL2 level. Overexpression of OVOL2 in SW620 cells decreased their migration and invasion, reduced markers of the epithelial-to-mesenchymal transition, and suppressed their metastasis as xenograft tumors in nude mice; knockdown of OVOL2 caused LS174T cells to transition from epithelial to mesenchymal phenotypes. OVOL2 bound T-cell factor (TCF)4 and ß-catenin, facilitating recruitment of histone deacetylase 1 to the TCF4-ß-catenin complex; this inhibited expression of epithelial-to-mesenchymal transition-related genes regulated by WNT, such as SLUG, in CRC cell lines. OVOL2 was a downstream target of WNT signaling in LS174T and SW480 cells. The OVOL2 promoter was hypermethylated in late-stage CRC specimens from patients and in SW620 cells; hypermethylation resulted in OVOL2 down-regulation and an inability to inhibit WNT signaling. Disruption of Ovol2 in Apc(min/+) mice increased WNT activity in intestinal tissues and the formation of invasive intestinal tumors. CONCLUSIONS: OVOL2 is a colorectal tumor suppressor that blocks WNT signaling by facilitating the recruitment of histone deacetylase 1 to the TCF4-ß-catenin complex. Strategies to increase levels of OVOL2 might be developed to reduce colorectal tumor progression and metastasis.