Desmoglein 2 and desmocollin 2 depletions promote malignancy through distinct mechanisms in triple-negative and luminal breast cancer.

BACKGROUND: Aberrant expressions of desmoglein 2 (Dsg2) and desmocollin 2(Dsc2), the two most widely distributed desmosomal cadherins, have been found to play various roles in cancer in a context-dependent manner. Their specific roles on breast cancer (BC) and the potential mechanisms remain unclear. METHODS: The expressions of Dsg2 and Dsc2 in human BC tissues and cell lines were assessed by using bioinformatics analysis, immunohistochemistry and western blotting assays. Wound-healing and Transwell assays were performed to evaluate the cells' migration and invasion abilities. Plate colony-forming and MTT assays were used to examine the cells' capacity of proliferation. Mechanically, Dsg2 and Dsc2 knockdown-induced malignant behaviors were elucidated using western blotting assay as well as three inhibitors including MK2206 for AKT, PD98059 for ERK, and XAV-939 for ß-catenin. RESULTS: We found reduced expressions of Dsg2 and Dsc2 in human BC tissues and cell lines compared to normal counterparts. Furthermore, shRNA-mediated downregulation of Dsg2 and Dsc2 could significantly enhance cell proliferation, migration and invasion in triple-negative MDA-MB-231 and luminal MCF-7 BC cells. Mechanistically, EGFR activity was decreased but downstream AKT and ERK pathways were both activated maybe through other activated protein tyrosine kinases in shDsg2 and shDsc2 MDA-MB-231 cells since protein tyrosine kinases are key drivers of triple-negative BC survival. Additionally, AKT inhibitor treatment displayed much stronger capacity to abolish shDsg2 and shDsc2 induced progression compared to ERK inhibition, which was due to feedback activation of AKT pathway induced by ERK inhibition. In contrast, all of EGFR, AKT and ERK activities were attenuated, whereas ß-catenin was accumulated in shDsg2 and shDsc2 MCF-7 cells. These results indicate that EGFR-targeted therapy is not a good choice for BC patients with low Dsg2 or Dsc2 expression. Comparatively, AKT inhibitors may be more helpful to triple-negative BC patients with low Dsg2 or Dsc2 expression, while therapies targeting ß-catenin can be considered for luminal BC patients with low Dsg2 or Dsc2 expression. CONCLUSION: Our finding demonstrate that single knockdown of Dsg2 or Dsc2 could promote proliferation, motility and invasion in triple-negative MDA-MB-231 and luminal MCF-7 cells. Nevertheless, the underlying mechanisms were cellular context-specific and distinct.

Doxycycline inhibits the adhesion and migration of melanoma cells by inhibiting the expression and phosphorylation of focal adhesion kinase (FAK).

Doxycycline has been found to induce apoptosis and to inhibit the growth of a variety of tumor cells, in addition to its use as an antibiotic. However, the mechanism of its actions, especially at the molecular level, remains unknown and needs to be resolved. A crucial step possibly lies in the early period of doxycycline administration, which leads to a series of cascading effects depicting the consequential biological action of doxycycline on tumor cells. The present study focuses on the early-stage effects of doxycycline administration, specifically at the stages of treatment (before 16h). In this paper, we report that doxycycline inhibits the adhesion and migration of melanoma cells. Afterwards, the cells undergo apoptosis (aniokis). Remarkably, doxycycline also inhibits the expression and phosphorylation of focal adhesion kinase (FAK), a protein tyrosine kinase involved in the regulation of cell adhesion and migration. We further demonstrate that doxycycline down-regulates the activities of MMP-2 and MMP-9, and its effects are stronger than those of an Integrin beta1 antibody. Finally, we suggest that doxycycline might exert its anti-tumor effects by inhibiting FAK signaling pathway. These results provide an insight into the possible mechanisms that underlie the multiple drug actions of doxycycline. The potential use of doxycycline in anti-tumor treatment is promising and warrants further studies.

A pilot study on acute inflammation and cancer: a new balance between IFN-gamma and TGF-beta in melanoma.

Recent data have redefined the concept of inflammation as a critical component of tumor progression. However, there has been little development on cases where inflammation on or near a wound and a tumor exist simultaneously. Therefore, this pilot study aims to observe the impact of a wound on a tumor, to build a new mouse tumor model with a manufactured surgical wound representing acute inflammation, and to evaluate the relationship between acute inflammation or wound healing and the process of tumor growth. We focus on the two phases that are present when acute inflammation influences tumor. In the early phase, inhibitory effects are present. The process that produces these effects is the functional reaction of IFN-gamma secretions from a wound inflammation. In the latter phase, the inhibited tumor is made resistant to IFN-gamma through the release of TGF-beta to balance the inflammatory factor effect on the tumor cells. A pair of cytokines IFN-gamma/TGF-beta established a new balance to protect the tumor from the interference effect of the inflammation. The tumor was made resistant to IFN-gamma through the release of TGF-beta to balance the inflammatory effect on the tumor cells. This balance mechanism that occurred in the tumor cells increased proliferation and invasion. In vitro and in vivo experiments have confirmed a new view of clinical surgery that will provide more detailed information on the evaluation of tumors after surgery. This study also provides a better understanding of the relationship between tumor and inflammation, as well as tumor cell attacks on inflammatory factors.

[Correlation of vasculogenic mimicry with clinicopathologic features and prognosis of ovarian carcinoma].

OBJECTIVE: To explore the existence of vasculogenic mimicry (VM) in ovarian carcinoma and its correlationship with the clinicopathologic features and prognosis of the tumor. METHODS: A total of 84 ovarian carcinoma cases were collected with complete clinical and prognostic data. CD31 immunohistochemistry and PAS special stain were used to investigate VM in the tumor tissue. Immunohistochemical staining of VEGF, MMP-2, MMP-9, E-cadherin, beta-catenin, and Vimentin were used to explore the pathogenesis of VM. RESULTS: Totally 36 of 84 cases exhibited evidence of VM. FIGO classification, pathologic grades and histological types were significantly different between the VM and non-VM groups. Expression of VEGF, MMP-2, MMP-9, E-cadherin and beta-catenin were higher in the VM group than in the non-VM group. Kaplan-Meier survival curve analysis showed that cases of the VM group had a lower survival rate than that of the non-VM group (P = 0.04). CONCLUSIONS: Vasculogenic mimicry exists in ovarian carcinoma. Ovarian carcinomas with a high grade malignancy have a high incidence of VM formation, a higher incidence of metastases and a lower survival rate. High expression of MMP-2 and MMP-9 may contribute to the formation of VM in the ovarian cancer.

Functional significance of VEGF-a in human ovarian carcinoma: role in vasculogenic mimicry.

Ovarian cancer is a silent killer, and shows early extensive tumor invasion and peritoneal metastasis. The microcirculation of most tumors includes cooperation of pre-existing vessels, intussusceptive microvascular growth, postnatal vasculogenesis, glomeruloid angiogenesis and vasculogenic mimicry (VM). VM is critical for a tumor blood supply and is asscociated with aggressive features and metastasis. Our studies highlight the plasticity of aggressive human ovarian carcinoma cells and call into question the underlying significance of their ability to form VM in vitro induced by VEGF-a. These studies also show their clinicalpathological features of the cancers with human Paraffin-embedded tumor tissue samples. Results show that the process: VEGF-a-->EphA2-->MMPs-->VM is the main pathway for VM formation and VEGF-a appears to play an important role in the formation of VM based on our in vitro assays and clinical immunohistochemical analyses. VM-targeting strategies for ovarian cancer include anti-VEGF-a treatment, knocking down the EphA2 gene and using antibodies against human MMPs if the tumor is VM positive. This strategy may be of significant value in laying the foundation for a more explicit anti-tumor angiogenesis therapy.

Pilot study on the interaction between B16 melanoma cell-line and bone-marrow derived mesenchymal stem cells.

Bone-marrow derived mesenchymal stem cells (BMSCs) have the potential to differentiate into osteocytes, chondrocytes, adipocytes and endothelial cells. The interaction between BMSCs and epithelial tumor cell was enhanced on proliferation. Our previous study had shown that BMSCs maybe participate in angiogenesis in melanoma in vivo. The aim of this study was to investigate the interaction between B16 melanoma cells and BMSCs in vitro, the mechanism of BMSCs participating in melanoma angiogenesis in vivo is unclear, so a co-culture system containing BMSCs and B16 melanoma cells, based on transwell indirect model, was established, and the interaction between BMSCs and B16 melanoma cells was studied in vitro. In our study, BMSCs were generated out of bone marrow from C57 mouse, isolated BMSCs were positive for the markers CD105, CD90, CD73, CD44 and CD166 and negative for endothelial markers, which acquired endothelial phenotype (including the expression of VEGFR-1, VEGFR-2, Factor VIII) after co-culture with B16 melanoma cells; at the same time, B16 melanoma cells also up-regulated the expression of VEGF-a, VEGFR-1, VEGFR-2 and Factor VIII. The proliferation rate of B16 melanoma cells and BMSCs were also found to be increased. We could show the differentiation of BMSCs into cells with phenotypic features of endothelial cells. BMSCs promoted proliferation of tumor cells and improved the microenvironment in tumor. Our study suggests that the BMSCs may play an important role in tumor angiogenesis.

[The influence of different microenvironments on melanoma invasiveness and microcirculation patterns].

OBJECTIVE: To investigate the influence of different microenvironments on tumor microcirculation patterns and invasive capability. METHODS: Melanoma B16 cells were injected into the peritoneal cavity and skeletal muscle of C57 mice synchronously. CK18 expression in melanoma was assessed to distinguish the malignant phenotype of tumors in the peritoneal cavity from that in the skeletal muscle. HIF-1alpha, MMP-2 and MMP-9 protein and mRNA expression were compared in the two microenvironments. Cells positive for each immunohistochemical stain and the vessels representative of each type of microcirculation pattern were evaluated in two microenvironments. RESULTS: CK18 and HIF-1alpha expression in melanoma were significantly higher in the skeletal muscle than in the peritoneal cavity (t = 8.142, t = 3.645, P < 0.05). Compared with the peritoneal cavity, melanoma cells in the skeletal muscle overexpressed MMP-2 and MMP-9 (t = 4.916, t = 7.782, P < 0.05). Real time-PCR results also showed that MMP-2 and MMP-9 mRNA levels in melanoma were higher in the skeletal muscle than in the peritoneal cavity (t = 36.814, t = 26.025, P < 0.05). Vasculogenic mimicry channels and endothelium-dependent vessels were the major microcirculation patterns in the skeletal muscle and in the peritoneal cavity respectively. CONCLUSIONS: Different microenvironments affect invasiveness and blood supply patterns of melanoma. Different microenvironment induced tumor cell secretion of more invasion-related proteins and affect invasiveness and blood supply patterns of melanoma.

[Study on the molecular mechanism of endostatin and doxycycline in suppressing melanoma growth].

OBJECTIVE: To investigate the molecular mechanism of endostatin and doxycycline effect on melanoma growth. METHODS: A B16 melanoma mice model was established by intracutaneous injection of B16 cell suspension. The mice were treated with endostatin, doxycycline, endostatin and doxycycline respectively, the control group received no treatment. A time course study of tumor volume was performed to observe the antitumor effect. The expression of matrix metalloproteinase (MMP-9), MMP-2, TIMP-2 were examined by immunohistochemistry staining. RESULTS: Tumors in endostatin treatment group, doxycycline treatment group, endostatin and doxycycline treatment group grew slower than in the control group. The difference of the average tumor volume in the doxycycline group and control group, in the doxycycline with endostatin treatment group and control group were statistically different. The positive expression ratio of MMP-2, MMP-9, TIMP-2 in each treatment group were statistically different from their control groups (F = 12.79, F = 5.56, F = 4.64; P < 0.05). CONCLUSION: Doxycycline and endostatin are able to inhibit the expression of MMPs and promote expression of TIMP, which ultimately inhibits the growth of B16 melonoma.