Unique cellular interactions between pancreatic cancer cells and the omentum.

Pancreatic cancer is a common cause of cancer-related mortality. Omental spread is frequent and usually represents an ominous event, leading to patient death. Omental metastasis has been studied in ovarian cancer, but data on its role in pancreatic cancer are relatively scarce and the molecular biology of this process has yet to be explored. We prepared tissue explants from human omental fat, and used conditioned medium from the explants for various in vitro and in vivo experiments designed to evaluate pancreatic cancer development, growth, and survival. Mass spectrometry identified the fat secretome, and mRNA array identified specific fat-induced molecular alternations in tumor cells. Omental fat increased pancreatic cancer cellular growth, migration, invasion, and chemoresistance. We identified diverse potential molecules secreted by the omentum, which are associated with various pro-tumorigenic biological processes. Our mRNA array identified specific omental-induced molecular alternations that are associated with cancer progression and metastasis. Omental fat increased the expression of transcription factors, mRNA of extracellular matrix proteins, and adhesion molecules. In support with our in vitro data, in vivo experiments demonstrated an increased pancreatic cancer tumor growth rate of PANC-1 cells co-cultured for 24 hours with human omental fat conditioned medium. Our results provide novel data on the role of omental tissue in omental metastases of pancreatic cancer. They imply that omental fat secreted factors induce cellular reprogramming of pancreatic cancer cells, resulting in increased tumor aggressiveness. Understanding the mechanisms of omental metastases may enable us to discover new potential targets for therapy

Gastric Cancer-Derived Extracellular Vesicles (EVs) Promote Angiogenesis via Angiopoietin-2

Angiogenesis is an important control point of gastric cancer (GC) progression and metastasis. Angiopoietin-2 (ANG2) is a key driver of tumor angiogenesis and metastasis, and it has been identified in primary GC tissues. Extracellular vesicles (EVs) play an important role in mediating intercellular communication through the transfer of proteins between cells. However, the expression of ANG2 in GC-EVs has never been reported. Here, we characterized the EV-mediated crosstalk between GC and endothelial cells (ECs), with particular focus on the role of ANG2. We first demonstrate that ANG2 is expressed in GC primary and metastatic tissues. We then isolated EVs from two different GC cell lines and showed that these EVs enhance EC proliferation, migration, invasion, and tube formation in vitro and in vivo. Using an angiogenesis protein array, we showed that GC-EVs contain high levels of proangiogenic proteins, including ANG2. Lastly, using Lenti viral ANG2-shRNA, we demonstrated that the proangiogenic effects of the GC-EVs were mediated by ANG2 through the activation of the PI3K/Akt signal transduction pathway. Our data suggest a new mechanism via which GC cells induce angiogenesis. This knowledge may be utilized to develop new therapies in gastric cancer

Development of a New Model of Humeral Hemiarthroplasty in Rats

Purpose In vivo models are anatomically comparable to humans allowing to reproduce the patterns and progression of the disease and giving the opportunity to study the symptoms and responses to new treatments and materials. This study aimed to establish a valid and cost-effective in vivo rat model to assess the effects of implanted shoulder hemiarthroplasty materials on glenoid articular cartilage wear. Methods Eight adult male Wistar rats underwent right shoulder hemi-arthroplasty. A stainless steel metal bearing was used as a shoulder joint prosthesis. X-rays were performed one week after surgery to verify correct implant position. Additional X-rays were performed 30 and 60 days post-implantation. Animals were sacrificed 24 weeks after implantation. All specimens were evaluated with micro-CT for cartilage and bone wear characteristics as well as histologically for signs of osteoarthritis. Samples were compared to the non-operated shoulders. Results All animals recovered and resumed normal cage activity. All X-rays demonstrated correct implant positioning except for one in which the implant was displaced. Histologic evaluation demonstrated arthritic changes in the implanted shoulder. Decreased Trabecular thickness and Trabecular Spacing were documented among the implanted parties (p < .05). Bone Mineral Density and Tissue Mineral Density were reduced in the operated shoulder although not significantly (p = .07). Conclusions This study demonstrated significant glenoid cartilage wearing in the operated shoulder. Furthermore, the presence of an intra-articular hemiarthroplasty implant diminished underlying glenoid bone quality. This novel, in vivo-model will enable researchers to test implant materials and their effects on cartilage and bone tissue in a cost-effective reproducible rat model

Delayed Wound Healing in Heat Stable Antigen (HSA/CD24)-Deficient Mice.

Healthy individuals rarely have problems with wound healing. Most skin lesions heal rapidly and efficiently within one to two weeks. However, many medical and surgical complications can be attributed to deficiencies in wound repair. Open wounds have lost the barrier that protects tissues from bacterial invasion and allows the escape of vital fluids. Without expeditious healing, infections become more frequent. The CD24 gene encodes a heavily-glycosylated cell surface protein anchored to the membrane by phosphatidylinositol. CD24 plays an important role in the adaptive immune response and controls an important genetic checkpoint for homeostasis and autoimmune diseases in both mice and humans. We have previously shown that overexpression of CD24 results in increased proliferation and migration rates.To examine the role of CD24 in the wound healing process.An excisional model of wound healing was used and delayed wound healing was studied in genetically modified heat stable antigen (HSA/CD24)-deficient mice (HSA-/-) compared to wild-type (WT) mice.Large full-thickness skin wounds, excised on the back of mice, exhibited a significant delay in the formation of granulation tissue, and in wound closure when compared to their WTHSA+/+ littermates. Wounds were histologically analyzed and scored, based on the degree of cellular invasion, granulation tissue formation, vascularity, and re-epithelialization. Additionally, in stitched wounds, the HSA-/- mice failed to maintain their stitches; they did not hold and fell already 24 hours, revealing erythematous wound fields. Re-expression of HSA, delivered by lentivirus, restored the normal healing phenotype, within 24 hours post-injury, and even improved the healing in WT, and in BalbC mice.Delayed wound-healing in the absence of HSA/CD24 suggests that CD24 plays an important role in this process. Increased expression of CD24, even in the normal state, may be used to enhance wound repair

Omental fat CM enhances pancreatic cancer cell migration and invasion.

<p>(A) Wound healing scratch assay demonstrating the effect of omental fat CM on PANC-1 and MIA-PaCa-2 cell migration; Scale bar = 200 μm. (B); Modified Boyden chamber assays depicting the effects of omental fat CM on pancreatic cancer cell migration (<i>P<</i> .001); (C) Matrigel invasion chamber demonstrating a significant increase in invasion of PANC-1 and MIA-PaCa-2 cells pre-treated with omental fat CM (<i>P</i>< .05); (D) Increased invasion of PANC-1 and MIA-PaCa-2 cells by using omental fat CM as a chemoattractant (<i>P</i> < .01). The upper panel graphs represent the average of 5 repeated experiments ± SD, and the lower panel depicts representative images (magnification, X100).</p

Omental fat CM enhances pancreatic cancer cell growth.

<p>(A) XTT assay demonstrating a significant increase (<i>P</i>< .01) in proliferation of pancreatic cancer cells after incubation with omental fat CM, n = 7; (B) Omental fat CM markedly increased pancreatic cancer cell colony formation capacity (<i>P</i>< .01). The upper panel graphs represent the average of four repeated independent experiments ±SD, and the lower panel depicts representative images of cell colonies in soft agar (magnification, X100); (C) Omental fat CM-induced S-phase population in pancreatic cancer cells; a more pronounced effect was seen in PANC-1 cells than in MIA-PaCa-2 cells (<i>P</i>< .05). Bar plots display the data of 7 independent experiments.</p

Molecular characterization of omental fat CM-treated PANC-1 cells.

<p>(A) PCA of gene expression microarray data. The PCA graphs of global gene expression data were computed using Partek GS, version 6.6; RM control samples are shown as red spheres, n = 3; CM samples are shown as yellow spheres, n = 9. (B) Affymetrix microarray hierarchical clustering performed on mRNA of PANC-1 cells treated with omental fat CM compared to RM. A colored bar indicating the standardized log2 intensities accompanies the expression profile. (C) qRT-PCR validation of the expression levels of OPN in PANC-1 cells pretreated with omental fat CM compared to RM, n = 6. Cells were analyzed by Western blot for the expression of <i>OPN</i> protein levels. α-actinin was used as a protein loading control, n = 6.</p

Cancer-related genes identified by mRNA array analysis of PANC-1 cells pre-treated with omental fat conditioned medium (CM) versus control regular medium (RM).

<p>Cancer-related genes identified by mRNA array analysis of PANC-1 cells pre-treated with omental fat conditioned medium (CM) versus control regular medium (RM).</p

Cancer-related proteins identified by LC-MS/MS analysis of human omental fat (OF) versus subcutaneous fat (SC).

<p>Cancer-related proteins identified by LC-MS/MS analysis of human omental fat (OF) versus subcutaneous fat (SC).</p