ROR2 regulates cellular plasticity in pancreatic neoplasia and adenocarcinoma.

Cellular plasticity is a hallmark of pancreatic ductal adenocarcinoma (PDAC) starting from the conversion of normal cells into precancerous lesions to the progression of carcinoma subtypes associated with aggressiveness and therapeutic response. We discovered that normal acinar cell differentiation, maintained by the transcription factor Pdx1, suppresses a broad gastric cell identity that is maintained in metaplasia, neoplasia, and the classical subtype of PDAC in mouse and human. We have identified the receptor tyrosine kinase Ror2 as marker of a gastric metaplasia (SPEM)-like identity in the pancreas. Ablation of Ror2 in a mouse model of pancreatic tumorigenesis promoted a switch to a gastric pit cell identity that largely persisted through progression to the classical subtype of PDAC. In both human and mouse pancreatic cancer, ROR2 activity continued to antagonize the gastric pit cell identity, strongly promoting an epithelial to mesenchymal transition, conferring resistance to KRAS inhibition, and vulnerability to AKT inhibition.

Engineering tumor constructs to study matrix-dependent angiogenic signaling of breast cancer cells.

Breast cancer is the leading cause of cancer deaths among females globally. The crosstalk between tumor microenvironment and neoplastic cells is the key for promoting tumor growth, stimulating tumor angiogenesis, and metastasis to distant organs. Thus, it is highly important to investigate tumor cell-matrix interactions to facilitate screening of different anti-cancer agents, individually or in combination. We, herein report, the development of an in vitro three-dimensional (3D) breast cancer model to investigate the effect of stromal crosslinking and consequent, stiffening on the angiogenic activity of cancer cells. Crosslinking of collagen gels was altered via non-enzymatic glycation and highly aggressive breast cancer cells, MDA-MB-231, were encapsulated in these gels. Cells encapsulated in glycated/stiffer matrices displayed an increased expression of pro-angiogenesis-related signals. Inhibition of mechanotransduction pathways on the angiogenic activity of aggressive tumor cells in stiff matrices was investigated using Y-27632, blebbistatin, and cytochalasin D. Rho-associated kinase (ROCK) inhibitor, Y-27632, diminished the pro-angiogenic signaling, thereby suggesting the potential dependence of breast cancer cells on the Rho/ROCK pathway in regulating tumor angiogenesis. Our findings highlight the potential of the developed model to be used as a tool to investigate matrix-associated tumor angiogenesis and screen different therapeutic agents towards inhibiting it.

Potency of Combining Eucalyptus camaldulensis subsp. camaldulensis with Low-Dose Cisplatin in A549 Human Lung Adenocarcinomas and MCF-7 Breast Adenocarcinoma.

Background: Lung and breast cancers are common in the world and represent major public health problems. Systemic chemotherapy is an effective way to prolong survival but it is associated with side effects. Plants are used as traditional treatments for many types of cancers, mostly in combination with chemotherapy. We investigated the antitumor effect of ethanolic (EE) and aqueous (AE) extracts of Eucalyptus camaldulensis on human alveolar adenocarcinoma basal epithelial cells (A549) and breast adenocarcinoma cell line (MCF-7) and checked the synergistic effect of the combination with low-dose cisplatin (CDDP). Methods: AE and EE were characterized for their secondary metabolites including content of phenol and antioxidant activity of both extracts. Cell viability was tested by the neutral red assay and MTT. Combinations of extract with low-dose CDDP on A549, MCF-7 cells, and normal cells peripheral blood mononuclear cells was used to study cell viability. Results: AE contains higher level of active constituents than EE. Higher antioxidant activity was observed in AE. Both extracts showed cytotoxic activity on A549 and MCF-7 cells. Moreover, combining E. camaldulensis with low-dose CDDP increases significantly the cell death of treated cells in comparison to those treated with CDDP alone. Conclusions: Our results highlight a new therapeutic concept that combines Eucalyptus camaldulensis with low-dose CDDP to treat lung and breast adenocarcinoma.

Engineering microenvironments towards harnessing pro-angiogenic potential of mesenchymal stem cells.

Mesenchymal stem cell (MSC)-based therapy for promoting vascular regeneration is a promising strategy for treating ischemic diseases. However, low engraftment and retention rate of MSCs at the target site highlights the importance of paracrine signaling of MSCs in the reparative process. Thus, harnessing MSC-secretome is essential for rational design of MSC-based therapies. The role of microenvironment in regulating the paracrine signaling of MSCs is not well known. In this study, human bone marrow-derived MSCs were seeded on matrices with varying stiffness or cell adhesive sites, and conditioned media was collected. The concentrations of angiogenic molecules in the media was measured via ELISA. In addition, the bioactivity of the released molecules was investigated via assessing the proliferation and capillary morphogenesis of human umbilical vein endothelial cells (HUVECs) incubated with conditioned media. Our study revealed that secretion of vascular endothelial growth factor (VEGF) is dependent on substrate stiffness. Maximal secretion was observed when MSCs were seeded on hydrogel matrices of 5.0 kPa stiffness. Proliferation and tubulogenesis of HUVECs supported ELISA data. On the other hand, variation of cell adhesive sites while maintaining a uniform optimal stiffness, did not influence the pro-angiogenic activity of MSCs.

Investigation of Integrated Effects of Hydroxyapatite and VEGF on Capillary Morphogenesis of Endothelial Cells.

Major drawbacks of using autografts and allografts for repairing large bone defects/injuries are the shortage of available tissues and potential disease transmission. Bone tissue engineering is believed to be a promising alternative to bone grafts. The concomitant formation of vascular networks within the tissue engineered constructs for successful bone regeneration still remains a challenge. The physicochemical properties of a tissue microenvironment are known to regulate vascular network formation. However, our understanding of the mechanism, by which endothelial cells integrate these physicochemical signals emanating from the microenvironment to undergo capillary morphogenesis, is limited. In this study, the integrated effects of the vascular endothelial growth factor (VEGF), pro-angiogenic molecule, and hydroxyapatite (HA), widely used as an additive and a scaffold in bone reconstructive surgery, on capillary formation of human umbilical vein endothelial cells (HUVECs) were investigated. Toward this, HUVECs were seeded on scaffolds composed of 15% (w/v) poly(ethylene glycol) diacrylate, 5% (w/v) gelatin methacrylate (GelMA), and 1% (w/v) photoinitiator. The concentration of HA was varied from 0% to 0.2% (w/v). The study demonstrated that HA elicited an inhibitory response. The presence of VEGF promoted a sprouting response with a significant enhancement in the number of sprouts observed in the case of gels with higher concentrations of HA.