Comparative Study of Tumor Targeting and Biodistribution of pH (Low) Insertion Peptides (pHLIP® Peptides) Conjugated with Different Fluorescent Dyes

Purpose Acidification of extracellular space promotes tumor development, progression, and invasiveness. pH (low) insertion peptides (pHLIP® peptides) belong to the class of pH-sensitive membrane peptides, which target acidic tumors and deliver imaging and/or therapeutic agents to cancer cells within tumors. Procedures Ex vivo fluorescent imaging of tissue and organs collected at various time points after administration of different pHLIP® variants conjugated with fluorescent dyes of various polarity was performed. Methods of multivariate statistical analyses were employed to establish classification between fluorescently labeled pHLIP® variants in multidimensional space of spectral parameters. Results The fluorescently labeled pHLIP® variants were classified based on their biodistribution profile and ability of targeting of primary tumors. Also, submillimeter-sized metastatic lesions in lungs were identified by ex vivo imaging after intravenous administration of fluorescent pHLIP® peptide. Conclusions Different cargo molecules conjugated with pHLIP® peptides can alter biodistribution and tumor targeting. The obtained knowledge is essential for the design of novel pHLIP®-based diagnostic and therapeutic agents targeting primary tumors and metastatic lesions

Involvement of Cyr61 in growth, migration, and metastasis of prostate cancer cells

Cyr61 has been reported to participate in the development and progression of various cancers; however, its role in prostate cancer (PCa) still remains poorly understood. In this study, we explored the function of Cyr61 in a series of malignant PCa cell lines, including LnCap, Du145, and PC3. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and crystal violet assays demonstrated that Cyr61 was essential for the proliferation of PCa cells. Soft agar assay and xenograft analysis showed that downregulation of Cyr61 suppressed the tumorigenicity of Du145 cells both in vitro and in vivo. Either silencing the cellular Cyr61 by RNA interference or neutralising the endogenous Cyr61 by antibody inhibited the migration of Du145 cells. In contrast, purified protein of Cyr61 promoted the migration of LnCap cells in a dose-dependent manner. These results suggested that Cyr61 was involved in the migration of PCa cells. We also observed the accumulation of mature focal adhesion complexes associated with the impaired migration through Cyr61 downregulation. Also, further studies showed that Cyr61 regulated the level of activated Rac1 as well as its downstream targets, including phosphorylated JNK, E-cadherin, and p27kip1, which are key molecules involved in cell growth, migration, and invasion. The in vivo mouse tail vein injection experiment revealed that Cyr61 affected the metastatic capacity of Du145 cells, suggesting that Cyr61 was required for prostate tumour metastasis. Altogether, our results demonstrated that Cyr61 played an important role in the tumorigenicity and metastasis of PCa cells, which will benefit the development of therapeutic strategy for PCas

Antimitotic drugs in the treatment of cancer

Cancer is a complex disease since it is adaptive in such a way that it can promote proliferation and invasion by means of an overactive cell cycle and in turn cellular division which is targeted by antimitotic drugs that are highly validated chemotherapy agents. However, antimitotic drug cytotoxicity to non-tumorigenic cells and multiple cancer resistance developed in response to drugs such as taxanes and vinca alkaloids are obstacles faced in both the clinical and basic research field to date. In this review, the classes of antimitotic compounds, their mechanisms of action and cancer cell resistance to chemotherapy and other limitations of current antimitotic compounds are highlighted, as well as the potential of novel 17-β estradiol analogs as cancer treatment.Medical Research Council of South Africa, the Research Committee of the Faculty of Health Sciences of the University of Pretoria, the Cancer association of South Africa and the National Research Foundation.http://link.springer.com/journal/280hb201

Normoxic cells remotely regulate the acid‐base balance of cells at the hypoxic core of connexin‐coupled tumor growths

A significant proportion of ATP fuels the removal of metabolic end-products, particularly H+ ions which profoundly affect biological activities. Since energetic resources in hypoxic tumor-regions are constrained by low-yielding glycolysis, any means of reducing the cost of acid-extrusion, without compromising pH homeostasis, would be advantageous. Some cancers express connexin channels for allowing solute exchange, and we propose that, via this route, normoxic cells supply hypoxic neighbors with acid-neutralizing HCO3 − ions. This was tested by imaging cytoplasmic pH in spheroidal tissue-growths of connexin43-positive pancreatic cancer Colo357 cells during light-controlled H+ -uncaging at the hypoxic core. Acid-retention in hypoxic cells was halved in the presence of CO2/HCO3 − , but requires a restorative flux of HCO3 − ions. The effect of CO2/HCO3 − was ablated by connexin43 inhibition or knockdown. In connexin-decoupled spheroids, DIDS, an inhibitor of extracellular HCO3 − uptake, had no effect on cytoplasmic [H+ ] in the H+ -uncaging region, indicating that DIDS-sensitive transport is not an adequate pH-regulatory strategy at the hypoxic core. Under functional connexin-coupling, acid-retention in hypoxic cells increased with DIDS, indicating that HCO3 − ions are taken-up actively by peripheral cells and then transmitted passively to hypoxic cells. Thus, the energetic burden of pH regulation is off-loaded from hypoxic cells onto metabolically-altruistic normoxic neighbors

Polyamine-dependent activation of Rac1 is stimulated by focal adhesion-mediated Tiam1 activation

Integrin receptors cluster on the cell surface and bind to extra cellular matrix (ECM) proteins triggering the formation of focal contacts and the activation of various signal transduction pathways that affect the morphology, motility, gene expression and survival of adherent cells. Polyamine depletion prevents the increase in autophosphorylation of focal adhesion kinase (FAK) and Src during attachment. Rac activity also shows a steady decline, and its upstream guanine nucleotide exchange factor (GEF), Tiam1 also shows a reduction in total protein level when cells are depleted of polyamines. When Tiam1 and Rac1 interaction was inhibited by NSC-23766, there was not only a decrease in Rac1 activity as expected but also a decrease in FAK auto-phosphorylation. Inhibition of Src activity by PP2 also reduced FAK autophosphorylation, which implies that Src modulates FAK autophosphorylation. From the data obtained in this study we conclude that FAK and Src are rapidly activated upon fibronectin mediated signaling leading to Tiam1-mediated Rac1 activation and that intracellular polyamines influence the signaling strength by modulating interaction of Src with Tiam1 using focal adhesion kinase as a scaffolding site

Precision medicine in pancreatic disease-knowledge gaps and research opportunities: Summary of a national institute of diabetes and digestive and kidney diseases workshop

A workshop on research gaps and opportunities for Precision Medicine in Pancreatic Disease was sponsored by the National Institute of Diabetes and Digestive Kidney Diseases on July 24, 2019, in Pittsburgh. The workshop included an overview lecture on precision medicine in cancer and 4 sessions: (1) general considerations for the application of bioinformatics and artificial intelligence; (2) omics, the combination of risk factors and biomarkers; (3) precision imaging; and (4) gaps, barriers, and needs to move from precision to personalized medicine for pancreatic disease. Current precision medicine approaches and tools were reviewed, and participants identified knowledge gaps and research needs that hinder bringing precision medicine to pancreatic diseases. Most critical were (a) multicenter efforts to collect large-scale patient data sets from multiple data streams in the context of environmental and social factors; (b) new information systems that can collect, annotate, and quantify data to inform disease mechanisms; (c) novel prospective clinical trial designs to test and improve therapies; and (d) a framework for measuring and assessing the value of proposed approaches to the health care system. With these advances, precision medicine can identify patients early in the course of their pancreatic disease and prevent progression to chronic or fatal illness

Animal Models: Challenges and Opportunities to Determine Optimal Experimental Models of Pancreatitis and Pancreatic Cancer.

At the 2018 PancreasFest meeting, experts participating in basic research met to discuss the plethora of available animal models for studying exocrine pancreatic disease. In particular, the discussion focused on the challenges currently facing the field and potential solutions. That meeting culminated in this review, which describes the advantages and limitations of both common and infrequently used models of exocrine pancreatic disease, namely, pancreatitis and exocrine pancreatic cancer. The objective is to provide a comprehensive description of the available models but also to provide investigators with guidance in the application of these models to investigate both environmental and genetic contributions to exocrine pancreatic disease. The content covers both nongenic and genetically engineered models across multiple species (large and small). Recommendations for choosing the appropriate model as well as how to conduct and present results are provided