Expression of the clustered NeuAcα2-3Galβ O-glycan determines the cell differentiation state of the cells

Selective targeting of lectins and their macropinocytosis in urothelial tumours: translation from in vitro to ex vivo

Urinary bladder cancer can be treated by intravesical application of therapeutic agents, but the specific targeting of cancer urothelial cells and the endocytotic pathways of the agents are not known. During carcinogenesis, the superficial urothelial cells exhibit changes in sugar residues on the apical plasma membranes. This can be exploited for selective targeting from the luminal side of the bladder. Here we show that the plant lectins Jacalin (from Artocarpus integrifolia), ACA (from Amaranthus caudatus) and DSA (from Datura stramonium) selectively bind to the apical plasma membrane of low- (RT4) and high-grade (T24) cancer urothelial cells in vitro and urothelial tumours ex vivo. The amount of lectin binding was significantly different between RT4 and T24 cells. Endocytosis of lectins was observed only in cancer urothelial cells and not in normal urothelial cells. Transmission electron microscopy analysis showed macropinosomes, endosome-like vesicles and multivesicular bodies filled with lectins in RT4 and T24 cells and also in cells of urothelial tumours ex vivo. Endocytosis of Jacalin and ACA in cancer cells was decreased in vitro after addition of inhibitor of macropinocytosis 5-(N-ethyl-N-isopropyl) amiloride (EIPA) and increased after stimulation of macropinocytosis with epidermal growth factor (EGF). Clathrin, caveolin and flotillin did not colocalise with lectins. These results confirm that the predominant mechanism of lectin endocytosis in cancer urothelial cells is macropinocytosis. Therefore, we propose that lectins in combination with conjugated therapeutic agents are promising tools for improved intravesical therapy by targeting cancer cells.

Carbohydrate 3′-sialyllactose as a novel target for theranostics in pancreatic ductal adenocarcinoma

We previously demonstrated that the carbohydrate 3′-sialyllactose is overexpressed in cancer stem-like cells such as metastatic pancreatic and poorly differentiated gastric cancer cells, and undifferentiated human embryonic stem cells. In this study, we investigated the possibility of 3′-sialyllactose as a target for theranostics in cancers using a recombinant mouse monoclonal antibody r3B1E2 that binds to 3′-sialyllactose. Immunohistochemistry analysis confirmed an elevated expression of 3′-sialyllactose in tumors of pancreas, stomach, and testis, while no expression of 3′-sialyllactose was observed in corresponding normal controls. In addition, a stage-independent expression of 3′-sialyllactose was observed, especially in pancreatic ductal adenocarcinoma (PDAC). The level of serum 3′-sialyllactose in PDAC subjects was significantly higher than that in healthy controls, providing excellent AUC of 0.88. We next explored the therapeutic potential of r3B1E2 for PDAC in vitro. Treatment of r3B1E2 with 3′-sialyllactose-bearing human PDAC cells exhibited a complement-dependent cytotoxicity, whereas no significant activity of r3B1E2 against 3′-sialyllactose-negative cells was observed. Collectively, these findings raise the possibility of 3′-sialyllactose as a novel target for theranostics in PDAC.

TRA-1-60-positive/CD45low cells found in the peripheral blood of prostate cancer patients with metastatic disease - A proof-of-concept study

Purpose

Over 90% of all cancer related deaths are due to metastasis. However, current diagnostic tools can't reliably discriminate between invasive and localized cancers.

Patients and methods

In this proof-of-concept study, we employed the embryonic stem cell marker TRA-1-60 (TRA+) to identify TRA + cells within the blood of prostate cancer patients and searched for TRA + cells in men with metastatic and localized cancers. We isolated whole peripheral blood mononuclear cells from 26 metastatic prostate cancer patients, from 13 patients with localized prostate cancer and from 17 healthy controls. Cells were stained for DAPI, CD45 and TRA + by immunofluorescence and imaged by epi-fluorescence microscopy. Imaged-based software was used both to identify TRA + cells, and to analyze CD45 levels in TRA+ and negative cells.

Results

We found high numbers of TRA + cells within the blood of metastatic cancer patients, whereas healthy individuals or men with localized prostate cancer showed none or very low numbers of TRA + cells. Further analysis of the CD45 levels of TRA + cells revealed a small population of TRA + cells with almost undetectable CD45 levels that were found frequently in metastatic prostate cancer patients. By excluding CD45 positive cells from the TRA + cell pool, we were able to refine the assay to be highly specific in identifying men with metastatic disease. In fact, the difference of CD45 levels between TRA+ and negative cells was a robust measure to distinguish between men with localized and metastatic prostate cancers in this small patient cohort.

Conclusions

The data suggest that metastatic prostate cancer patient have significant numbers of TRA+/CD45^low cells which might represent a potential tool for diagnostic assessment in the future.

Circulating natural antibodies against 3'-sialyllactose complement the diagnostic performance of CA19-9 for the early detection of pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma is a devastating malignancy with an extremely poor prognosis. Although the most widely used biomarker for pancreatic cancer is carbohydrate antigen CA19-9, it is elevated mainly in the late stage of pancreatic cancer. Some serum natural antibodies against carbohydrates have been shown to be possible diagnostic markers for cancer.

OBJECTIVE

This study was conducted to determine whether the level of natural antibodies against carbohydrates fluctuates in pancreatic ductal adenocarcinoma.

METHODS

Serum from pancreatic cancer subjects (n= 55) and 43 subjects free of malignant disease were studied. The contents of natural antibodies against sialyl glycans and CA19-9 in serum were determined by enzyme-linked immunosorbent assay.

RESULTS

The level of serum anti-3'-sialyllactose antibodies in pancreatic cancer subjects was significantly lower than that in healthy controls. In contrast, the amounts of serum antibodies against other sialyl glycans were comparable between the two groups. Concentration of serum anti-3'-sialyllactose IgG provided excellent AUC of 0.86, with sensitivity 82%, specificity 81%, and accuracy 82%. The combination of serum anti-3'-sialyllactose IgG with CA19-9 improved the sensitivity of pancreatic cancer detection at an early stage.

CONCLUSIONS

Natural antibodies against 3'-sialyllactose constitute a promising biomarker for pancreatic cancer detection. The measurement of serum anti-3'-sialyllactose antibodies could play a supportive role in diagnostics and complement the performance of CA19-9 for the early detection of pancreatic ductal adenocarcinoma.

Intracellular Catalysis with Selected Metal Complexes and Metallic Nanoparticles: Advances toward the Development of Catalytic Metallodrugs

Platinum-containing drugs (e.g., cisplatin) are among the most frequently used chemotherapeutic agents. Their tremendous success has spurred research and development of other metal-based drugs, with notable achievements. Generally, the vast majority of metal-based drug candidates in clinical and developmental stages are stoichiometric agents, i.e., each metal complex reacts only once with their biological target. Additionally, many of these metal complexes are involved in side reactions, which not only reduce the effective amount of the drug but may also cause toxicity. On a separate note, transition metal complexes and nanoparticles have a well-established history of being potent catalysts for selective molecular transformations, with examples such as the Mo- and Ru-based catalysts for metathesis reactions (Nobel Prize in 2005) or palladium catalysts for C-C bond forming reactions such as Heck, Negishi, or Suzuki reactions (Nobel Prize in 2010). Also, notably, no direct biological equivalent of these transformations exists in a biological environment such as bacteria or mammalian cells. It is, therefore, only logical that recent interest has focused on developing transition-metal based catalytic systems that are capable of performing transformations inside cells, with the aim of inducing medicinally relevant cellular changes. Because unlike in stoichiometric reactions, a catalytically active compound may turn over many substrate molecules, only very small amounts of such a catalytic metallodrug are required to achieve a desired pharmacologic effect, and therefore, toxicity and side reactions are reduced. Furthermore, performing catalytic reactions in biological systems also opens the door for new methodologies to study the behavior of biomolecules in their natural state, e.g., via in situ labeling or by increasing/depleting their concentration at will. There is, of course, an art to the choice of catalysts and reactions which have to be compatible with biological conditions, namely an aqueous, oxygen-containing environment. In this review, we aim to describe new developments that bring together the far-distant worlds of transition-metal based catalysis and metal-based drugs, in what is termed "catalytic metallodrugs". Here we will focus on transformations that have been performed on small biomolecules (such as shifting equilibria like in the NAD⁺/NADH or GSH/GSSG couples), on non-natural molecules such as dyes for imaging purposes, or on biomacromolecules such as proteins. Neither reactions involving release (e.g., CO) or transformation of small molecules (e.g., ¹O₂ production), degradation of biomolecules such as proteins, RNA or DNA nor light-induced medicinal chemistry (e.g., photodynamic therapy) are covered, even if metal complexes are centrally involved in those. In each section, we describe the (inorganic) chemistry involved, as well as selected examples of biological applications in the hope that this snapshot of a new but quickly developing field will indeed inspire novel research and unprecedented interactions across disciplinary boundaries.

Generation of Novel Anti-MUC1 Monoclonal Antibodies with Designed Carbohydrate Specificities Using MUC1 Glycopeptide Library

Numerous anti-mucin 1 (anti-MUC1) antibodies that recognize O-glycan core structures have already been developed. However, most of them show low specificities toward O-glycan structures and/or low affinity toward a monovalent epitope. In this study, using an MUC1 glycopeptide library, we established two novel anti-MUC1 monoclonal antibodies (1B2 and 12D10) with designed carbohydrate specificities. Compared with previously reported anti-MUC1 antibodies, 1B2 and 12D10 showed quite different features regarding their specificities, affinities, and reactivity profiles to various cell lines. Both antibodies recognized specific O-glycan structures at the PDT*R motif (the asterisk represents an O-glycosylation site). 1B2 recognized O-glycans with an unsubstituted O-6 position of the GalNAc residue (Tn, T, and 23ST), whereas 12D10 recognized Neu5Ac at the same position (STn, 26ST, and dST). Neither of them bound to glycopeptides with core 2 O-glycans that have GlcNAc at the O-6 position of the GalNAc residue. Furthermore, 1B2 and 12D10 showed a strong binding to not only native MUC1 but also 20-mer glycopeptide with a monovalent epitope. These anti-MUC1 antibodies should thus become powerful tools for biological studies on MUC1 O-glycan structures. Furthermore, the strategy of using glycopeptide libraries should enable the development of novel antibodies with predesigned O-glycan specificities.

Generation of Rat Monoclonal Antibodies Against Human Pancreatic Ductal Adenocarcinoma Cells

Pancreatic ductal adenocarcinoma is an aggressive tumor with a poor prognosis. Biomarkers that can detect the tumor in its early stages when it may be amenable to curative resection might improve prognosis. To discover novel markers expressed in primary pancreatic cancer, we generated a panel of monoclonal antibodies against pancreatic ductal adenocarcinoma cell line BxPC3 using a rat medial iliac lymph node method. The antigen recognized by 1B5A5 was expressed on the cell surface and secreted into the conditioned medium of BxPC3 cells, and characterized as glycoproteins with molecular mass between 60 and 90 kDa. A wide range of molecular weights of 1B5A5 antigen in several pancreatic cancer cell lines were observed. Immunohistochemistry using a human multiple organ tumor tissue array showed an enhanced expression of 1B5A5 antigen in pancreas, lung, stomach, breast, urinary bladder, colon, and cervix uteri cancers. Immunoprecipitation followed by proteomic analyses identified CEACAM6 as a 1B5A5 antigen. In addition, western blot analysis results indicated that the 1B5A5 epitope is located within an amino-terminal domain of CEACAM6. These results raised the possibility that our approach could lead to discovery of novel biomarkers for the early stage of cancers in a relatively short period of time.

Process of hepatic metastasis from pancreatic cancer: biology with clinical significance

PURPOSE

Pancreatic cancer shows a remarkable preference for the liver to establish secondary tumors. Selective metastasis to the liver is attributed to the development of potential microenvironment for the survival of pancreatic cancer cells. This review aims to provide a full understanding of the hepatic metastatic process from circulating pancreatic cancer cells to their settlement in the liver, serving as a basic theory for efficient prediction and treatment of metastatic diseases.

METHODS

A systematic search of relevant original articles and reviews was performed on PubMed, EMBASE and Cochrane Library for the purpose of this review.

RESULTS

Three interrelated phases are delineated as the contributions of the interaction between pancreatic cancer cells and the liver to hepatic metastasis process. Chemotaxis of disseminated pancreatic cancer cells and simultaneous defensive formation of platelets or neutrophils facilitate specific metastasis toward the liver. Remodeling of extracellular matrix and stromal cells in hepatic lobules and angiogenesis induced by proangiogenic factors support the survival and growth of clinical micrometastasis colonizing the liver. The bimodal role of the immune system or prevalence of cancer cells over the immune system makes metastatic progression successfully proceed from micrometastasis to macrometastasis.

CONCLUSIONS

Pancreatic cancer is an appropriate research object of cancer metastasis representing more than a straight cascade. If any of the successive or simultaneous phases, especially tumor-induced immunosuppression, is totally disrupted, hepatic metastasis will be temporarily under control or even cancelled forever. To shrink cancers on multiple fronts and prolong survival for patients, novel oral or intravenous anti-cancer agents covering one or different phases of metastatic pancreatic cancer are expected to be integrated into innovative strategies on the premise of safety and efficacious biostability.