Focal adhesion kinase regulates the phosphorylation protein tyrosine phosphatase-α at Tyr789 in breast cancer cells

Phosphoinositide Conversion Inactivates R-RAS and Drives Metastases in Breast Cancer

Breast cancer is the most prevalent cancer and a major cause of death in women worldwide. Although early diagnosis and therapeutic intervention significantly improve patient survival rate, metastasis still accounts for most deaths. Here it is reported that, in a cohort of more than 2000 patients with breast cancer, overexpression of PI3KC2α occurs in 52% of cases and correlates with high tumor grade as well as increased probability of distant metastatic events, irrespective of the subtype. Mechanistically, it is demonstrated that PI3KC2α synthetizes a pool of PI(3,4)P2 at focal adhesions that lowers their stability and directs breast cancer cell migration, invasion, and metastasis. PI(3,4)P2 locally produced by PI3KC2α at focal adhesions recruits the Ras GTPase activating protein 3 (RASA3), which inactivates R-RAS, leading to increased focal adhesion turnover, migration, and invasion both in vitro and in vivo. Proof-of-concept is eventually provided that inhibiting PI3KC2α or lowering RASA3 activity at focal adhesions significantly reduces the metastatic burden in PI3KC2α-overexpressing breast cancer, thereby suggesting a novel strategy for anti-breast cancer therapy.

PBN11-8, a Cytotoxic Polypeptide Purified from Marine Bacillus, Suppresses Invasion and Migration of Human Hepatocellular Carcinoma Cells by Targeting Focal Adhesion Kinase Pathways

The development of antitumor drugs has attracted cancer researchers and the identification of novel antitumor lead compounds is certainly of great interest. The fermentation broth of Bacillus sp. N11-8, which was isolated from the Antarctic waters, showed cytotoxicity towards different cells. A cytotoxic polypeptide, PBN11-8, was purified from the fermentation broth of Bacillus sp. N11-8 using ultrafiltration, ammonium sulfate precipitation, anion exchange liquid chromatography and high performance liquid chromatography (HPLC). Cloning and sequence analysis showed that PBN11-8 polypeptide (MW: ~19 kDa by the electrospray-ionization (ESI)) displayed high similarity with peptidase M84 from Bacillus pumilus. PBN11-8 possessed moderate cytotoxicity towards several cancer cell lines with IC₅₀ values of 1.56, 1.80, 1.57, and 1.73 µg/mL against human hepatocellular carcinoma cell line BEL-7402, human renal clear cell adenocarcinoma cell line 786-0, human hepatocellular carcinoma cell line HepG2, and human pancreatic cancer cell line Panc-28, respectively. Moreover, the polypeptide displayed weak cytotoxicity towards normal cell line renal tubular epithelial cell line HK2 and human normal liver cell line L02 cells. Wound healing migration and Transwell experiments demonstrate that PBN11-8 could inhibit the migration and invasion of BEL-7402. Further investigation revealed that PBN11-8 suppresses focal adhesion kinase (FAK)-mediated adhesion, migration, and invasion by disturbing FAK/extracellular regulated protein kinases (ERK) signaling and matrix metalloproteinase-2(MMP-2) and matrix metalloproteinase-9 (MMP-9) in BEL-7402 cells. Thus, PBN11-8 represents a potential novel anti-cancer lead compound.

Zirconia stimulates ECM-remodeling as a prerequisite to pre-osteoblast adhesion/proliferation by possible interference with cellular anchorage

The biological response to zirconia (ZrO₂) is not completely understood, which prompted us to address its effect on pre-osteoblastic cells in both direct and indirect manner. Our results showed that zirconia triggers important intracellular signaling mainly by governing survival signals which leads to cell adhesion and proliferation by modulating signaling cascade responsible for dynamic cytoskeleton rearrangement, as observed by fluorescence microscopy. The phosphorylations of Focal Adhesion Kinase (FAK) and Rac1 decreased in response to ZrO₂ enriched medium. This corroborates the result of the crystal violet assay, which indicated a significant decrease of pre-osteoblast adhesion in responding to ZrO₂ enriched medium. However, we credit this decrease on pre-osteoblast adhesion to the need to govern intracellular repertory of intracellular pathways involved with cell cycle progression, because we found a significant up-phosphorylation of Mitogen-Activated Protein Kinase (MAPK)-p38 and Cyclin-dependent kinase 2 (CDK2), while p15 (a cell cycle suppressor) decreased. Importantly, Protein phosphatase 2 A (PP2A) activity decreased, guaranteeing the significant up-phosphorylation of MAPK -p38 in response to ZrO₂ enriched medium. Complementarily, there was a regulation of Matrix Metalloproteinases (MMPs) in response to Zirconia and this remodeling could affect cell phenotype by interfering on cell anchorage. Altogether, our results show a repertory of signaling molecules, which suggests that ECM remodel as a pre-requisite to pre-osteoblast phenotype by affecting their anchoring in responding to zirconia.

Diallyl disulfide effect on the invasion and migration ability of HL-60 cells with a high expression of DJ-1 in the nucleus through the suppression of the Src signaling pathway

The present study examined the effect of diallyl disulfide (DADS) on the invasion and migration ability of HL-60 cells with a high expression of parkinsonism associated deglycase (DJ-1) in the nucleus (HHDN), and its molecular mechanism. A western blot assay was used to measure the effects of DADS and an Src inhibitor on the expression of DJ-1 and the Src signal pathway in HHDN. The effects of DADS and Src inhibitors on the invasion and migration ability of HHDN was detected using Transwell migration and invasion chamber experiments. The experiments were divided into three groups: A control group (HL-60 cells), an empty vector group and a high expression group (HHDN cells). Western blot assays revealed that the expression of DJ-1 in HHDN was inhibited in a time-dependent manner following treatment with DADS for 24, 48 and 72 h. Following DADS treatment, the expression of phosphorylated Src (p-Src) and phosphorylated Fak (p-Fak) were significantly decreased in all groups compared with the untreated groups, however the expression level of Src, Fak and integrin did not change significantly. Western blot analysis results revealed that following treatment with DADS and Src inhibitor, the expression levels of p-Src and p-Fak significantly decreased in all three groups compared with untreated groups, whereas the expression levels of Src, Fak and integrin did not change significantly. The expression of DJ-1 in HHND was inhibited in time-dependent manner following treatment with DADS and Src inhibitor for 24, 48 and 72 h. Transwell migration and invasion assay results revealed that DADS and Src inhibitors may suppress migration and invasion in leukemic cells, and a combination of the two treatments may result in more efficient suppression. DADS may downregulate DJ-1-mediated invasion and migration in leukemic cells through suppressing the Src-Fak-Integrin signaling pathway, and the Src inhibitor may enhance the antitumor effect of DADS.

Nano hydroxyapatite-blasted titanium surface creates a biointerface able to govern Src-dependent osteoblast metabolism as prerequisite to ECM remodeling

Over the last several years, we have focused on the importance of intracellular signaling pathways in dynamically governing the biointerface between pre-osteoblast and surface of biomaterial. Thus, this study investigates the molecular hallmarks involved in the pre-osteoblast relationship with different topography considering Machined (Mc), Dual Acid-Etching (DAE), and nano hydroxyapatite-blasted (nHA) groups. There was substantial differences in topography of titanium surface, considering Atomic Force Microscopy and water contact angle (Mc = 81.41 ± 0.01; DAE = 97.18 ± 0.01; nHA = 40.95 ± 0.02). Later, to investigate their topography differences on biological responses, pre-osteoblast was seeded on the different surfaces and biological samples were collected after 24 h (to consider adhesion signaling) and 10 days (to consider differentiation signaling). Preliminary results evidenced significant differences in morphological changes of pre-osteoblasts mainly resulting from the interaction with the DAE and nHA, distinguishing cellular adaptation. These results pushed us to analyze activation of specific genes by exploring qPCR technology. In sequence, we showed that Src performs crucial roles during cell adhesion and later differentiation of the pre-osteoblast in relationship with titanium-based biomaterials, as our results confirmed strong feedback of the Src activity on the integrin-based pathway, because integrin-ß1 (∼5-fold changes), FAK (∼12-fold changes), and Src (∼3.5-fold changes) were significantly up-expressed when Src was chemically inhibited by PP1 (5 μM). Moreover, ECM-related genes were rigorously reprogrammed in response to the different surfaces, resulting on Matrix Metalloproteinase (MMP) activities concomitant to a significant decrease of MMP inhibitors. In parallel, we showed PP1-based Src inhibition promotes a significant increase of MMP activity. Taking all our results into account, we showed for the first time nano hydroxyapatite-blasted titanium surface creates a biointerface able to govern Src-dependent osteoblast metabolism as pre-requisite to ECM remodeling.