Abstract C051: Ceramide signaling regulates PDA aggression through exosome reprogramming of the stroma

Ceramide is a bioactive lipid signaling molecule that regulates multiple cellular processes influencing pancreatic tumor progression and drug response. The pleiotropic role of ceramide signaling in cancer includes modulation of exosome biogenesis and secretion. Smpd3 encodes an enzyme that generates ceramide through hydrolysis of sphingomyelin. Employing the KPC mouse model of pancreatic cancer, we demonstrated that Smpd3 regulates exosome biogenesis in pancreatic ductal adenocarcinoma (PDA) cells and is pro-tumorigenic during PDA progression. Ablation of Smdp3 in KPC mice significantly extends survival by 19% when compared to KPC; Smpd3wt/wt controls. KPC; Smpd3f/f mice display significantly less PanIN and tumor burden compared to KPC; Smpd3wt/wt controls. Lipidomics analysis of epithelial cell lines generated from end-stage pancreatic tumors of KPC; Smpd3f/f and KPC; Smpd3wt/wt mice demonstrated an alteration in hundreds of lipid species including ceramides, triacylglycerides, sphingomyelins, and phosphatidylcholines. Analysis of RNA-seq data of these epithelial cell lines showed a switching of primary tumors from the predominant more aggressive basal-like subtype seen in KPC; Smpd3wt/wt mice to classical in KPC; Smpd3f/f mice. Pathways analysis of our RNA-seq dataset showed an enrichment for genes involved in cellular mechanics and regulation of the tumor microenvironment. To query if Smpd3-generated exosomes have a direct effect on pancreatic tumor progression, we injected KPC; Smpd3wt/wt and KPC; Smpd3f/f mice with exosomes isolated from KPC; Smpd3f/f and KPC; Smpd3wt/wt PDA cell lines. Injection of exosomes derived from KPC; Smpd3f/f mice significantly extended survival of both Smpd3wt/wt and KPC; Smpd3f/f mice when compared to injection of exosomes isolated from KPC; Smpd3wt/wt mice, suggesting an anti-tumorigenic effect of exosomes isolated from Smpd3-deficient PDA cell lines. We observed a decrease in extracellular matrix collagen abundance and fewer activated stellate cells and fibroblasts in KPC; Smpd3f/f compared to control KPC; Smpd3wt/wt pancreata. Abrogation of Smpd3 expression also affected immune cell infiltration, as demonstrated by a significant increase in iNOS+ F4/80+ double positive macrophages in KPC; Smpd3f/f pancreata when compared to KPC; Smpd3wt/wt pancreata. Loss of Smpd3 resulted in a significant reduction in CD31+ endothelial cells in pancreatic tumors of KPC; Smpd3f/f mice when compared to KPC; Smpd3wt/wt mice, which may influence the ability of chemotherapeutics to enter pancreatic tumors. Our patient data demonstrate that high SMPD3 expression in surgically resected, treatment naive PDA significantly correlated with longer patient survival when patients received adjuvant chemotherapy, more than 95% of which was gemcitabine. Collectively, our data show that ceramide-dependent exosomes promote tumorigenesis, specifically activation of stellate cells and fibroblasts – which may in turn induce a stiff, fibrotic, proinflammatory tumor microenvironment that also impedes vasculature formation.

Citation Format: Audrey M. Hendley, Atsushi Urano, Xianlu L. Peng, Sudipta Ashe, Natanya R. Kerper, Tuan A. Phu, Martin Ng, Simone Giacometti, David I. Berrios, Gun H. Jang, Jen J. Yeh, Steven Gallinger, David K. Chang, Andrew V. Biankin, Valerie M. Weaver, Grace E. Kim, David W. Dawson, Robert L. Raffai, Matthias Hebrok. Ceramide signaling regulates PDA aggression through exosome reprogramming of the stroma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C051.

Palladin promotes invasion of pancreatic cancer cells by enhancing invadopodia formation in cancer-associated fibroblasts

The stromal compartment surrounding epithelial-derived pancreatic tumors is thought to have a key role in the aggressive phenotype of this malignancy. Emerging evidence suggests that cancer-associated fibroblasts (CAFs), the most abundant cells in the stroma of pancreatic tumors, contribute to the tumor's invasion, metastasis and resistance to therapy, but the precise molecular mechanisms that regulate CAFs behavior are poorly understood. In this study, we utilized immortalized human pancreatic CAFs to investigate molecular pathways that control the matrix-remodeling and invasion-promoting activity of CAFs. We showed previously that palladin, an actin-associated protein, is expressed at high levels in CAFs of pancreatic tumors and other solid tumors, and also in an immortalized line of human CAFs. In this study, we found that short-term exposure of CAFs to phorbol esters reduced the number of stress fibers and triggered the appearance of individual invadopodia and invadopodial rosettes in CAFs. Molecular analysis of invadopodia revealed that their composition resembled that of similar structures (that is, invadopodia and podosomes) described in other cell types. Pharmacological inhibition and small interfering RNA knockdown experiments demonstrated that protein kinase C, the small GTPase Cdc42 and palladin were necessary for the efficient assembly of invadopodia by CAFs. In addition, GTPase activity assays showed that palladin contributes to the activation of Cdc42. In mouse xenograft experiments using a mixture of CAFs and tumor cells, palladin expression in CAFs promoted the rapid growth and metastasis of human pancreatic tumor cells. Overall, these results indicate that high levels of palladin expression in CAFs enhance their ability to remodel the extracellular matrix by regulating the activity of Cdc42, which in turn promotes the assembly of matrix-degrading invadopodia in CAFs and tumor cell invasion. Together, these results identify a novel molecular signaling pathway that may provide new molecular targets for the inhibition of pancreatic cancer metastasis.

A comparative evaluation of ultrasound molecular imaging, perfusion imaging, and volume measurements in evaluating response to therapy in patient-derived xenografts

Most pre-clinical therapy studies use the change in tumor volume as a measure for disease response. However, tumor size measurements alone may not reflect early changes in tumor physiology that occur as a response to treatment. Ultrasonic molecular imaging (USMI) and Dynamic Contrast Enhanced-Perfusion Imaging (DCE-PI) with ultrasound are two attractive alternatives to tumor volume measurements. Since these techniques can provide information prior to the appearance of gross phenotypic changes, it has been proposed that USMI and DCE-PI could be used to characterize response to treatment earlier than traditional methods. This study evaluated the ability of tumor volume measurements, DCE-PI, and USMI to characterize response to therapy in two different types of patient-derived xenografts (known responders and known non-responders). For both responders and non-responders, 7 animals received a dose of 30 mg/kg of MLN8237, an investigational aurora-A kinase inhibitor, for 14 days or a vehicle control. Volumetric USMI (target integrin:α av β3) and DCE-PI were performed on day 0, day 2, day 7, and day 14 in the same animals. For USMI, day 2 was the earliest point at which there was a statistical difference between the untreated and treated populations in the responder cohort (Untreated: 1.20 ± 0.53 vs. Treated: 0.49 ± 0.40; p < 0.05). In contrast, statistically significant differences between the untreated and treated populations as detected using DCE-PI were not observed until day 14 (Untreated: 0.94 ± 0.23 vs. Treated: 1.31 ± 0.22; p < 0.05). Volume measurements alone suggested no statistical differences between treated and untreated populations at any readpoint. Monitoring volumetric changes is the "gold standard" for evaluating treatment in pre-clinical studies, however, our data suggests that volumetric USMI and DCE-PI may be used to earlier classify and robustly characterize tumor response.

Effect of blood transfusion on outcome after pancreaticoduodenectomy for exocrine tumour of the pancreas

BACKGROUND

Blood transfusion is thought to have an immunosuppressive effect. The aims of this study were to examine survival in patients with pancreatic cancer receiving blood transfusion in association with pancreaticoduodenectomy, and to define preoperative risk factors for subsequent transfusion.

METHODS

A retrospective review was performed of a prospective database of patients with exocrine tumours of the head of the pancreas who had undergone pancreaticoduodenectomy between 1998 and 2003. Clinical data, transfusion records and preoperative laboratory values were recorded.

RESULTS

A total of 294 patients underwent pancreaticoduodenectomy for exocrine tumours in the pancreatic head. Of these, 140 (47.6 per cent) received a blood transfusion. Their median survival was 18 months, compared with 24 months for those who did not have a transfusion (P = 0.036). Postoperative transfusion, margin status and node stage were independent predictors of survival. Age and preoperative total bilirubin and haemoglobin levels were the only preoperative factors that correlated with transfusion.

CONCLUSION

In patients with exocrine tumours of the pancreas, blood transfusion should be avoided when possible. Preoperative risk factors can identify patients who are likely to require transfusion and would therefore benefit most from blood conservation methods.

Predictors of intensive care unit admission and related outcome for patients after pancreaticoduodenectomy

High-volume centers have low morbidity and mortality after pancreaticoduodenectomy (PD). Less is known about treatment pathways and their influence on intensive care unit (ICU) utilization. Patients who underwent PD at a tertiary cancer center during the five-year period between January 1998 and December 2003 were identified from a prospective database. Preoperative and intraoperative factors relating to ICU admission and outcome were analyzed. Five hundred ninety-one pancreaticoduodenectomies were performed during the study period. Of these, 536 patients had complete records for analysis. Of the 536 patients, 51 (10%) were admitted to the ICU after surgery. Admission to the ICU was associated with decreased overall survival (P < .0001). Of the preoperative predictors of ICU admission, serum creatinine, albumin, and increased body mass index (BMI) were associated with ICU admission (P = .02, .05, and .002, respectively). Age, blood glucose, diagnosis of diabetes mellitus, and chronic obstructive pulmonary disease were not predictive of ICU admission on univariate analysis. Of the intraoperative factors, longer operative time and estimated blood loss (EBL) correlated with ICU admission (P = .003 and .0001, respectively). On multivariate analysis, only preoperative BMI and intraoperative EBL were independent predictors of ICU admission (P = .03 and .003, respectively). Patients with a preoperative BMI greater than 30 had a substantially higher risk of ICU admission (relative risk 2.4). The majority of patients who undergo PD do not require admission to the ICU. Factors most associated with ICU admission after PD are increased preoperative BMI and intraoperative blood loss.

Transient attenuation of protein kinase Cepsilon can terminate a chronic hyperalgesic state in the rat

Recently we demonstrated that a single 3-day episode of carrageenan-induced acute cutaneous inflammation can create a chronic state of increased susceptibility to inflammatory hyperalgesia. In this latent "primed" state, although there is no ongoing hyperalgesia, the hyperalgesic response to subsequent challenges with inflammatory agent (prostaglandin E2; PGE2) is greatly enhanced. Furthermore, the PGE2-induced hyperalgesia in primed skin was found to require activity of the epsilon isozyme of protein kinase C (PKCepsilon), a second messenger that is not required for PGE2-induced hyperalgesia in control animals. In the present study we tested the hypothesis that activity of PKCepsilon not only plays a critical role in the expression of primed PGE2-induced hyperalgesia, but also in the development and maintenance of the primed state itself. Antisense oligodeoxynucleotide was employed to produce a decrease in PKCepsilon in the nerve, verified by Western blot analysis. PKCepsilon was found to be essential both for the development of carrageenan-induced hyperalgesic priming, as well as for the maintenance of the primed state. Furthermore, hyperalgesic priming could be induced by an agonist of PKCepsilon (pseudo-receptor octapeptide for activated PKCepsilon) at a dose that itself causes no hyperalgesia. The finding that transient inhibition of PKCepsilon can not only prevent the development of priming, but can also terminate a fully developed state of priming suggests the possibility that selective targeting PKCepsilon might be an effective new strategy in the treatment of chronic inflammatory pain.

Predicting chemotherapy response to paclitaxel-based therapy in advanced non-small-cell lung cancer with P-glycoprotein expression

BACKGROUND

It was reported that multidrug resistance gene 1 (MDR1) encoding human P-glycoprotein (Pgp) may play an important role in multidrug resistance of lung cancer. Therefore, before initiating chemotherapy, it is important to accurately determine the presence of Pgp in lung cancer, to achieve a satisfactory chemotherapy response.

OBJECTIVES

The aim of this study was to compare immunohistochemical analyses of Pgp expression and response to paclitaxel in non-small-cell lung cancer (NSCLC).

METHODS

Before chemotherapy with paclitaxel, 50 patients with stage IIIb or IV NSCLC were enrolled in this study. Immunohistochemical analyses were performed on multiple nonconsecutive sections of the biopsy specimens to determine Pgp expression. Chemotherapy response was evaluated in the 3rd month after completion of treatment by clinical and radiological methods.

RESULTS

All of the 28 (100%) cases with good response had negative Pgp expression and 15 of the 22 (68%) cases with poor response had positive Pgp expression (p < 0.05). No significant differences were found for other prognostic factors (age, sex, body weight loss, performance status, tumor cell type, and tumor stage) between good response and poor response groups.

CONCLUSIONS

Although Pgp expression in NSCLC does not fully predict chemotherapy response to paclitaxel-based therapy, detection of Pgp expression will aid in planning paclitaxel-based therapy for patients with advanced NSCLC. Further studies with a larger number of patients and a longer time of follow-up are necessary to confirm our findings.

Neuronal nicotinic acetylcholine receptor alpha3 subunit protein in rat brain and sympathetic ganglion measured using a subunit-specific antibody: regional and ontogenic expression

A synthetic peptide corresponding to the C-terminus of the alpha 3 subunit of the rat neuronal nicotinic acetylcholine receptor (nAChR) was used to generate a rabbit polyclonal alpha 3 antibody. The specificity of this antibody was characterized by immunoblotting, immunohistochemical and immunoprecipitation techniques. Using this antibody, the relative densities of the alpha 3 subunit were quantitatively determined in different brain regions and in superior cervical ganglion (SCG). Among these regions, SCG, interpeduncular nucleus (IPN) and pineal gland showed the highest levels of alpha 3 protein expression. Habenula and superior colliculi had intermediate levels of expression. Low levels were found in cerebral cortex, hippocampus and cerebellum. The ontogenic profile of the alpha 3 subunit in the SCG was also determined. The alpha 3 protein level is low at postnatal day (P 1), but increases rapidly during the first seven postnatal days. This level then plateaus and remains stable through postnatal day 35. These findings suggest that neuronal nAChRs containing the alpha 3 subunit participate in important roles in specific regions of the rat brain and the SCG.

Differential nuclear and cytoplasmic expression of PTEN in normal thyroid tissue, and benign and malignant epithelial thyroid tumors

Germline mutations in PTEN (MMAC1/TEP1) are found in patients with Cowden syndrome, a familial cancer syndrome which is characterized by a high risk of breast and thyroid neoplasia. Although somatic intragenic PTEN mutations have rarely been found in benign and malignant sporadic thyroid tumors, loss of heterozygosity (LOH) has been reported in up to one fourth of follicular thyroid adenomas (FAs) and carcinomas. In this study, we examined PTEN expression in 139 sporadic nonmedullary thyroid tumors (55 FA, 27 follicular thyroid carcinomas, 35 papillary thyroid carcinomas, and 22 undifferentiated thyroid carcinomas) using immunohistochemistry and correlated this to the results of LOH studies. Normal follicular thyroid cells showed a strong to moderate nuclear or nuclear membrane signal although the cytoplasmic staining was less strong. In FAs the neoplastic nuclei had less intense PTEN staining, although the cytoplasmic PTEN-staining intensity did not differ significantly from that observed in normal follicular cells. In thyroid carcinomas as a group, nuclear PTEN immunostaining was mostly weak in comparison with normal thyroid follicular cells and FAs. The cytoplasmic staining was more intense than the nuclear staining in 35 to 49% of carcinomas, depending on the histological type. Among 81 informative tumors assessed for LOH, there seemed to be an associative trend between decreased nuclear and cytoplasmic staining and 10q23 LOH (P = 0.003, P = 0.008, respectively). These data support a role for PTEN in the pathogenesis of follicular thyroid tumors.

Somatic mitochondrial DNA (mtDNA) mutations in papillary thyroid carcinomas and differential mtDNA sequence variants in cases with thyroid tumours

Somatic mutations in mtDNA have recently been identified in colorectal tumours. Studies of oncocytic tumours have led to hypotheses which propose that defects in oxidative phosphorylation may result in a compensatory increase in mitochondrial replication and/or gene expression. Mutational analysis of mtDNA in thyroid neoplasia, which is characterised by increased numbers of mitochondria and is also one of the most common sites of oncocytic tumours. has been limited to date. Using the recently developed technique of two-dimensional gene scanning, we have successfully examined 21 cases of thyroid tumours, six cases of non-neoplastic thyroid pathology, 30 population controls, nine foetal thyroid tissues and nine foetal tissues of non-thyroid origin, either kidney or liver. We have identified three different somatic mutations (23%) in papillary thyroid carcinomas. In addition, we have found significant differential distributions of mtDNA sequence variants between thyroid carcinomas and controls. Interestingly, these variants appear to be more frequent in the genes which encode complex I of the mitochondrial electron transport chain compared to normal population controls. These findings suggest first, that somatic mtDNA mutations may be involved in thyroid tumorigenesis and second, that the accumulation of certain non-somatic variants may be related to tumour progression in the thyroid.

Fine-structure deletion mapping of 10q22-24 identifies regions of loss of heterozygosity and suggests that sporadic follicular thyroid adenomas and follicular thyroid carcinomas develop along distinct neoplastic pathways

Previous studies have demonstrated frequent loss of heterozygosity (LOH) of markers on chromosome arm 10q in both follicular thyroid carcinomas (FTCs) and follicular thyroid adenomas (FAs). A novel tumor suppressor gene, PTEN, has been mapped to 10q23.3 and is the susceptibility gene for Cowden syndrome, an autosomal dominant disorder characterized by multiple hamartomas and a risk of benign and malignant tumors of the breast and thyroid. Studies examining the relationship of somatic PTEN status and follicular thyroid neoplasms have only demonstrated a variable subset of tumors that have somatic monoallelic deletions of PTEN, suggesting that other tumor suppressor genes may be present in this region. We therefore sought to conduct a detailed examination of LOH of 20 polymorphic markers in a 19-cM region spanning 10q22-24, including PTEN, in 44 FAs and 17 FTCs. Using this fine-structure somatic mapping approach, we defined at least two novel regions of LOH in follicular adenomas and follicular carcinomas, suggesting the presence of at least two distinct tumor suppressor genes that may play a role in thyroid neoplasia. Furthermore, the difference in patterns of LOH in adenomas versus carcinomas lends additional support to the hypothesis that adenomas and carcinomas can develop along two separate, nonserial pathways. Genes Chromosomes Cancer 26:322-328, 1999.

Synthesis of Platinum Ultrafine Particles in AOT Reverse Micelles

The synthesis of platinum ultrafine particles by the reduction of H2PtCl6 with hydrazine in AOT/isooctane reverse micellar solutions has been studied. By high-resolution electron microscope, electron diffraction pattern, and XRD analyses, the resultant particles have been found to be pure platinum of fcc structure. Their sizes were observed to increase with the increases in the molar ratio of water to AOT (omegaO) and in the concentration of H2PtCl6, while they decreased with the increase of hydrazine concentration. At a constant omegaO value, the size of platinum ultrafine particles was not affected significantly when the concentration ratio of hydrazine to H2PtCl6 was above 10, the AOT concentration increased from 0.1 to 0.6 M, and the temperature varied from 15 to 35 degrees C. Furthermore, the kinetic study of particle formation indicated that the nucleation time needed several minutes. The time for the growth of platinum ultrafine particles to their final size after nucleation was about one to several hours. It was observed that the formation rates increased with the increase of omegaO value and the concentrations of AOT and H2PtCl6, but they were not affected by hydrazine concentration when the concentration ratio of hydrazine to H2PtCl6 was above 10. Copyright 1999 Academic Press.

Reliability Study of Holographic Optical Elements Made with DuPont Photopolymer

We report reliability-test results of transmission-type holographic optical elements (HOE's) made with the DuPont photopolymer HRF-600. The reliability tests performed include 6000 cycles of liquid-to-liquid thermal-shock cycling (-55 degrees C-125 degrees C), 2200 cycles of air-to-air thermal cycling (-55 degrees C-125 degrees C), 1500 h of humidity testing (85 degrees C and a relative humidity of 85%), and 675 h of burn-in testing at 125 degrees C. A total of 210 holograms was tested, with 532 data points collected for diffraction-efficiency measurements. The results show that the average efficiency change after these tests is in the range of -4% to 0% and the standard deviation is only ~10%.

Alexandrite laser frequency doubling in beta-BaB(2)O(4) crystals

Efficient and tunable coherent ultraviolet (360-390 nm) generation in beta-BaB(2)O(4) crystals using type-I phase matching at room temperature is presented. The phase-matching angle is characterized with an alexandrite laser with a wavelength tuning range of 725-785 nm. The crystal angular bandwidth of 0.9 mrad-cm and spectralbandwidth of 1.15 nm-cm are also measured. UV output pulse energy of 105 mJ at 378 nm with 31% energy conversion efficiency is achieved.