NetrinG1+ cancer-associated fibroblasts generate unique extracellular vesicles that support the survival of pancreatic cancer cells under nutritional stress

It is projected that in 5 years, pancreatic cancer will become the second deadliest cancer in the United States. A unique aspect of pancreatic ductal adenocarcinoma (PDAC) is its stroma; rich in cancer-associated fibroblasts (CAFs) and a dense CAF-generated extracellular matrix (ECM). These pathogenic stroma CAF/ECM units cause the collapse of local blood vessels rendering the tumor microenvironment nutrient-poor. PDAC cells are able to survive this state of nutrient stress via support from CAF-secreted material, which includes small extracellular vesicles (sEVs). The tumor-supportive CAFs possess a distinct phenotypic profile, compared to normal-like fibroblasts, expressing NetrinG1 (NetG1) at the plasma membrane, and active Integrin α₅β₁ localized to the multivesicular bodies; traits indicative of poor patient survival. We herein report that NetG1⁺ CAFs secrete sEVs that stimulate Akt-mediated survival in nutrient-deprived PDAC cells, protecting them from undergoing apoptosis. Further, we show that NetG1 expression in CAFs is required for the pro-survival properties of sEVs. Additionally, we report that the above-mentioned CAF markers are secreted in distinct subpopulations of EVs; with NetG1 being enriched in exomeres, and Integrin α₅β₁ being enriched in exosomes. Finally, we found that NetG1 and Integrin α₅β₁ were detected in sEVs collected from plasma of PDAC patients, while their levels were significantly lower in plasma-derived sEVs of sex/age-matched healthy donors. The discovery of these tumor-supporting CAF-EVs elucidates novel avenues in tumor-stroma interactions and pathogenic stroma detection.

Abstract PR-006: Pulsed low-dose-rate radiation (PLDR) limits pancreatic pro-tumor stroma aggravation: Pre-clinical basis for an ongoing PLDR trail

Radiation, combined with radio-sensitizing chemotherapy, is used preoperatively as neoadjuvant therapy (NT) for borderline resectable pancreatic ductal adenocarcinoma (PDAC) with the intent of facilitating a curative surgical intervention. PDAC is uniquely characterized by an extensive fibrous microenvironment, desmoplasia, which can unintendedly be aggravated by NT to foster its pro-tumoral function. Radiation, as part of NT, is aimed at providing a margin adjacent to un-resectable vessels and sterilizing regional lymph nodes. Yet, to avoid the unintended desmoplastic aggravation, and because of a risk of toxicities associated with high doses due to the radio-sensitivity of adjacent small bowel and stomach, the total dose of NT radiation delivered to PDAC patients is classically modest. Therefore, NT radiation in PDAC patients is often lower than optimal for effective tumor cell elimination. Pulsed low-dose-rate (PLDR) radiation improves the safety of radiation treatment as it allows time for DNA damage repair in non-tumorous cells/tissues while simultaneously remaining as effective as continuous dose rate (CDR) radiation in cancer cells. In theory, PLDR could be amendable for increased radiation dosage. Of interest, the use of PLDR in pre-clinical animal studies revealed a systemic lowering of transforming growth factor beta (TGFβ), a known immunosuppressive factor. Hence, we posit that since cancer-associated fibroblasts (CAFs) produce TGFβ and constitute one of the most abundant cells in PDAC desmoplasia, variations in TGFβ levels in response to NT will inform on desmoplastic dynamic changes. Our team has developed means to assess CAF functions and activation statuses. These efforts were guided by generating a desmoplastic biomarker signature obtained from patient-harvested CAFs during the production of extracellular matrix (ECM), using our well-established in vitro 3D system. We employed this in vivo-mimetic system to test the hypothesis that PLDR limits pro-tumoral desmoplastic CAF aggravation. As part of the CAF functional signature, we tested levels of immunosuppressive TGFβ secretion, expression of netrin-G1, palladin, and others; together with the biogenesis of unique extracellular vesicles, and the production of ECMs capable of nurturing PDAC cells under starvation. During a 5-day assay, human PDAC 3D ECM producing CAFs were treated with gemcitabine (Gem; 5nm) plus 4Gy or 8Gy PLDR vs. CDR. Results indicated that Gem alone or with CDR indeed aggravated CAF’s pro-PDAC phenotype and function, while Gem combined with PDLR limited and sometimes reverted this functional pro-tumor CAF signature. Based on these results, we are poised to test this functional CAF/desmoplasia signature, as laboratory correlatives, in an ongoing clinical trial at Fox Chase Cancer Center. The phase I trial is a dose-escalation study of PLDR radiation and chemotherapy at standard and intensified doses in preoperative pancreatic cancer patients with toxicity, histopathologic, and CAF-informing translational endpoints.

Citation Format: Janusz Franco-Barraza, Tiffany Luong, Jessica K. Wong, Debora B. Vendramini-Costa, Ralph Francescone, Jaye C. Gardiner, Kristopher S. Raghavan, Joshua E. Meyer, Edna Cukierman. Pulsed low-dose-rate radiation (PLDR) limits pancreatic pro-tumor stroma aggravation: Pre-clinical basis for an ongoing PLDR trail [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PR-006.

Palladin isoforms 3 and 4 regulate cancer-associated fibroblast pro-tumor functions in pancreatic ductal adenocarcinoma

Pancreatic Ductal Adenocarcinoma (PDAC) has a five-year survival under 10%. Treatment is compromised due to a fibrotic-like stromal remodeling process, known as desmoplasia, which limits therapeutic perfusion, supports tumor progression, and establishes an immunosuppressive microenvironment. These processes are driven by cancer-associated fibroblasts (CAFs), functionally activated through transforming growth factor beta1 (TGFβ1). CAFs produce a topographically aligned extracellular matrix (ECM) that correlates with reduced overall survival. Paradoxically, ablation of CAF populations results in a more aggressive disease, suggesting CAFs can also restrain PDAC progression. Thus, unraveling the mechanism(s) underlying CAF functions could lead to therapies that reinstate the tumor-suppressive features of the pancreatic stroma. CAF activation involves the f-actin organizing protein palladin. CAFs express two palladin isoforms (iso3 and iso4) which are up-regulated in response to TGFβ1. However, the roles of iso3 and iso4 in CAF functions remain elusive. Using a CAF-derived ECM model, we uncovered that iso3/iso4 are required to sustain TGFβ1-dependent CAF activation, secrete immunosuppressive cytokines, and produce a pro-tumoral ECM. Findings demonstrate a novel role for CAF palladin and suggest that iso3/iso4 regulate both redundant and specific tumor-supportive desmoplastic functions. This study highlights the therapeutic potential of targeting CAFs to restore fibroblastic anti-tumor activity in the pancreatic microenvironment.

Engineering clinically-relevant human fibroblastic cell-derived extracellular matrices

Three-dimensional (3D) culturing models, replicating in vivo tissue microenvironments that incorporate native extracellular matrix (ECM), have revolutionized the cell biology field. Fibroblastic cells generate lattices of interstitial ECM proteins. Cell interactions with ECMs and with molecules sequestered/stored within these are crucial for tissue development and homeostasis maintenance. Hence, ECMs provide cells with biochemical and biomechanical cues to support and locally control cell function. Further, dynamic changes in ECMs, and in cell-ECM interactions, partake in growth, development, and temporary occurrences such as acute wound healing. Notably, dysregulation in ECMs and fibroblasts could be important triggers and modulators of pathological events such as developmental defects, and diseases associated with fibrosis and chronic inflammation such as cancer. Studying the type of fibroblastic cells producing these matrices and how alterations to these cells enable changes in ECMs are of paramount importance. This chapter provides a step-by-step method for producing multilayered (e.g., 3D) fibroblastic cell-derived matrices (fCDM). Methods also include means to assess ECM topography and other cellular traits, indicative of fibroblastic functional statuses, like naïve/normal vs. inflammatory and/or myofibroblastic. For these, protocols include indications for isolating normal and diseased fibroblasts (i.e., cancer-associated fibroblasts known as CAFs). Protocols also include means for conducting microscopy assessments, querying whether fibroblasts present with fCDM-dependent normal or CAF phenotypes. These are supported by discrete semi-quantitative digital imaging analyses, providing some imaging processing advice. Additionally, protocols include descriptions for effective fCDM decellularization, which renders cellular debris-free patho/physiological in vivo-like scaffolds, suitable as 3D substrates for subsequent cell culturing.

EGR1 regulates cellular metabolism and survival in endocrine resistant breast cancer

About 70% of all breast cancers are estrogen receptor alpha positive (ER+; ESR1). Many are treated with antiestrogens. Unfortunately, de novo and acquired resistance to antiestrogens is common but the underlying mechanisms remain unclear. Since growth of cancer cells is dependent on adequate energy and metabolites, the metabolomic profile of endocrine resistant breast cancers likely contains features that are deterministic of cell fate. Thus, we integrated data from metabolomic and transcriptomic analyses of ER+ MCF7-derived breast cancer cells that are antiestrogen sensitive (LCC1) or resistant (LCC9) that resulted in a gene-metabolite network associated with EGR1 (early growth response 1). In human ER+ breast tumors treated with endocrine therapy, higher EGR1 expression was associated with a more favorable prognosis. Mechanistic studies showed that knockdown of EGR1 inhibited cell growth in both cells and EGR1 overexpression did not affect antiestrogen sensitivity. Comparing metabolite profiles in LCC9 cells following perturbation of EGR1 showed interruption of lipid metabolism. Tolfenamic acid, an anti-inflammatory drug, decreased EGR1 protein levels and synergized with antiestrogens in inhibiting cell proliferation in LCC9 cells. Collectively, these findings indicate that EGR1 is an important regulator of breast cancer cell metabolism and is a promising target to prevent or reverse endocrine resistance.

A study on gelatin capsule brittleness: moisture tranfer between the capsule shell and its content

Variation in moisture content of the capsule shells either due to the change of storage conditions or the moisture transfer between the capsule shell and its contents may lead to undesired physical properties, such as capsule brittleness and stickiness. DMP 504, a developmental bile-acid sequestrant, is a strongly basic anion-exchange polymer which contains randomly distributed primary, secondary, tertiary, and quaternary amine groups in their hydrochoride salt form. The alkylammonium groups which comprise this polymer form a random network containing a high level of branching and a low level of cross-linking. DMP 504 is very hygroscopic and has a tendency to gain or lose moisture with ease. The transfer of moisture from the capsule shell to DMP 504 powder contained in a hard gelatin capsule can be expected, and if a low water content of the capsule shell is achieved, the capsules become brittle and fracture easily. The sorption isotherm for DMP 504 was generated by storing the drug substance under various relative humidity conditions. After equilibrium, the moisture contents for the samples of individual isotherm points were measured by thermogravimetric analyses. This report applies the sorption-desorption moisture transfer (SDMT) model to predict the equilibrium relative humidity in a system containing DMP 504 in hard gelatin capsules and to establish target loss on drying values for DMP 504 and the capsule shell. Application of this SDMT model resulted in finding a solution to the brittleness problem. The moisture levels of capsule shells and contents for two formulations in a 12-month stability program are also reported here. Results of this study further demonstrate that the SDMT model can be used as a tool to guide the formulator to select optimal initial moisture contents for the empty capsule shell and the formulation to avoid the incidence of brittle capsule problems.

Physical and chemical properties of DMP 504, a polyalkylammonium-based bile acid sequestrant

The purpose of this study was to characterize the physicochemical properties of DMP 504 and lay the foundation for formulation development. Thermal properties were characterized by DSC and TGA and moisture sorption and desorption by TGA. The association rate and equilibrium binding capacity of the polymer for a prototype bile acid was evaluated using cholic acid, and solid state stability was examined at 25 degrees C, 40 degrees C (with and without 5% added water), 60 degrees C, and 600 foot candles/25 degrees C. The solid state excipient compatibility of binary mixtures of DMP 504 and several commonly used pharmaceutical excipients was also evaluated. Thermal analysis of the polymer showed a glass transition temperature at approximately 95 degrees C and no melting point, indicating a highly amorphous macromolecular structure with thermal stability up to 250 degrees C. Moisture sorption and desorption isotherms at controlled humidity ranging from 11% to 97% RH did not display hysteresis. Cholic acid associated with DMP 504 extremely rapidly so that binding was essentially complete within 5 min. Scatchard analysis of the equilibrium binding of cholic acid to DMP 504 was unconventional, and indicated that the system was exhibiting positive cooperative behavior. Modeling the binding curve for a system exhibiting cooperative behavior indicated a maximum binding capacity of DMP 504 for cholic acid in phosphate buffered saline (pH 7.0) of 4.9 mumol/mg, and a cooperativity value, P, of 2.2 implying that binding of one molecule promotes the binding of additional molecules. DMP 504, a hygroscopic, amorphous cross-linked polymer with a tendency to gain or lose moisture with ease, is stable in the solid state, either drug substance alone or in presence of excipients, at normal storage temperatures and light, and under controlled conditions of humidity.

Degradation kinetics of DMP 777, an elastase inhibitor

PURPOSE

The objective was to evaluate the degradation profile of the elastase inhibitor DMP 777 and lay the foundation for formulation development.

METHODS

The pKa was determined by potentiometric titration in mixed-aqueous solvents. The degradation kinetics were studied as a function of pH, buffer concentration, ionic strength, methanol concentration and temperature using a stability-indicating HPLC assay. The degradation products were identified by LC-MS, NMR, and by comparison with authentic samples.

RESULTS

The pKa for the protonated piperazine nitrogen was estimated to be 7.04. The pH-rate profile is described by specific acid-, water-, and specific base-catalyzed pathways. The pH of maximum stability is in the range of 4 to 4.5 where water is the principal catalyst in the reaction. Buffer catalysis, primary salt effects and medium effects were observed. The proposed mechanism for acid catalyzed degradation is the rarely observed AAL1 which involves alkyl-nitrogen heterolysis. The driving force for the reaction appears to lie in the stability of the benzylic carbocation. The proposed mechanism for base catalyzed degradation is BAC2 which involves beta-lactam ring opening. The beta-lactam ring of DMP 777, a monolactam, appears to be as reactive as that in benzylpenicillin in the KOH controlled region where a similar mechanism of hydrolysis should be operative. A contributing factor to this increased reactivity may lie in the reduced basicity of the beta-lactam nitrogen making it a good leaving group.

CONCLUSIONS

The degradation profile indicates that development of a solution dosage form of DMP 777 with adequate shelf-life stability at room temperature is feasible.

Solubility enhancement of a bisnaphthalimide tumoricidal agent, DMP 840, through complexation

The purpose of this research was to enhance the aqueous solubility of DMP 840 by complexation with water-soluble and nontoxic agents, and to understand the nature of the interactions involved in complex formation using nuclear magnetic resonance (1H-NMR). The solubility of DMP 840 in water, saline, acetate buffers, and cosolvent mixtures was determined by high-performance liquid chromatography, and the effect of nicotinamide and pyridoxine concentrations on the solubility of DMP 840 was examined by the phase solubility method. 1H-NMR spectra were acquired in deuterated acetate buffer at 400 MHz on a Varian Unity-400 spectrometer. The aqueous solubility of DMP 840 was sensitive to the presence of chloride and acetate anions in solution, and did not improve in the presence of cosolvents. The use of the nontoxic and water-soluble complex-forming agents nicotinamide and pyridoxine, however, resulted in a linear increase in the aqueous solubility of DMP 840 with both ligands. The solubilization appears to be due to formation of 1:1 complexes between DMP 840 and the bioorganic ligands. The complexation constants were 15.57 M-1 for the DMP 840:nicotinamide complex and 13.36 M-1 for the DMP 840:pyridoxine complex. The NMR results indicate that the interaction is a result of vertical or plane-to-plane stacking and the complexation constants were in agreement with that obtained by phase solubility. The results suggest that the aqueous solubility of a poorly water soluble drug substance such as DMP 840 can be significantly enhanced by its complexation with water-soluble and nontoxic agents.

A phosphinic acid dipeptide analogue to stabilize peptide drugs during their intranasal absorption

A major challenge in intranasal delivery of peptides is to overcome the enzymatic barrier that limits their absorption. Aminopeptidase inhibitors may be useful for improving systemic delivery of peptide drugs administered nasally. A phosphinic acid dipeptide analogue, a transition-state analogue aminopeptidase inhibitor in which the phosphinate moiety exists in a tetrahedral state mimicking peptides during their enzymatic hydrolysis, was synthesized and tested nasally in situ in rats. This inhibitor was found to inhibit greatly the degradation of the model peptide leucine-enkephalin in the nasal perfusate at less than or equal to 2 microM concentrations. The nasal peptidase hydrolytic activity was reversible after exposure to the inhibitor. This inhibitor has the advantage of efficacy at very low concentrations and reversibility of effects.

A double-blind evaluation of alprazolam and imipramine in the treatment of major depression

This report describes the results of a multicentre collaborative study comparing the safety and efficacy of alprazolam with imipramine in patients suffering from major depressive disorder. Two hundred and eight patients diagnosed as major depression as per DSM-III criteria were randomly allocated to alprazolam (N= 105) or imipramine (N = 103) in a double-blind fashion. Detailed assessments were carried out for a period of six weeks. Results revealed that alprazolam was as effective as imipramine as an antidepressant. Side effects were less frequently reported with alprazolam.

Improved delivery through biological membranes. XXX. Synthesis and biological aspects of a 1,4-dihydropyridine based chemical delivery system for brain-sustained delivery of hydroxy CCNU

A redox chemical delivery system based on the NADH in equilibrium NAD+ model was applied to an active metabolite (D) of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), i.e. CCNU-OH. The 1,4-dihydrotrigonelline ester of CCNU-OH, N-(2-chloro ethyl)-N'-[trans-4-(1,4-dihydro-1-methyl-3-pyridinecarbonyloxy)cyc lohexyl]- N-nitrosourea (D-CDS) was prepared by a direct hydride transfer reaction of the corresponding pyridinium precursor (D-Q+) with a highly reactive 1-benzyl-1,2-dihydroisonicotinamide. The in vitro kinetics in biological fluids indicated facile oxidative conversion of D-CDS to D-Q+. An in vivo study showed that one intravenous injection to rats of D-CDS resulted in rapid brain accumulation of D-Q+, followed by a sustained release of CCNU-OH, while D-Q+ was rapidly eliminated from systemic circulation. The ratio of brain/blood concentration of D-Q+ was found to increase progressively with time. At an equimolar dose of CCNU-OH, the ratio of brain/blood concentration for CCNU-OH was found to be close to unity.

Midtrimester abortion with intravenous administration of 15 methyl prostaglandin F2 alpha

In a trial of 71 women, 15(S) 15 methyl PGF2 alpha was administered intravenously at the dose level of 1 microgram/min for termination of pregnancy of between 11 weeks and 20 weeks of gestation. Sixty-one subjects (85.9%) aborted within 30 h of administration of the drug. The mean induction abortion interval was 15.65 h. The mean number of episodes of vomiting and diarrhea was 0.9 and 0.6, respectively. The effectiveness of the method is comparable to that of intramuscular method of administration, but the side effects are much less in comparison.

Stability of serum lithium levels-usefulness and relevance in Indian conditions

Two groups of patients on regular lithium therapy were studied to find out the stability in values of serum lithium over a period of time. Serum samples of one group was stored at -4°C while that of other group at room temperature. These samples were subsequently analysed over a period of eight days and subjected to statistical analysis. It was seen that values on the first day did not differ significantly from values of subsequent days. Implications of this findings are discussed in Indian conditions as lithium estimation facilities are available only at a few centres.

Radioimmunoassay of oxytocin

The evaluation of a radioimmunoassay of oxytocin is described. The method involved careful collection and transportation of blood at 4 degrees C, acidification of the plasma, extraction with Fuller's earth and radioimmunoassay using antisera raised in rabbits immunized against oxytocin conjugated to bovine serum albumin and 125I-labelled oxytocin. The antisera showed insignificant cross-reaction with a variety of small peptides including vasopressin and vasotocin. The limit of detection of the assay was 2.5 pg with intra-assay and interassay coefficients of variation of 7-15% and 12-18% respectively. Seventy-seven per cent (88 out of 116) of the pregnant women tested had detectable maternal plasma oxytocin. Serial samples of maternal plasma showed a significant increase in oxytocin from the first to the second stage of labour and a significant decrease in the third stage. Oxytocin concentrations in the umbilical arterial plasma were significantly higher in patients in labour. The significance of these findings is discussed.

Effect of prostaglandin F2 alpha and hypertonic saline on the placental function during midtrimester abortion

Changes in placental function during the induction of midtrimester abortion by prostaglandin F2 alpha and hypertonic saline were investigated. Serial estimations of human placental lactogen (HPL) and cystine aminopeptidase (CAP) were carried out in 17 subjects. There was a significant (P smaller than 0.01) reduction in the plasma CAP and HPL levels 4 hours after PGF2 alpha administration. In the case of hypertonic saline abortions only HPL levels showed a reduction at 8 and 12 hours after induction.