Clinical pharmacogenomic testing impacts therapy decisions and supportive medication choices in breast cancer

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Background: Pharmacogenomics, the study of the interaction between the patient’s genome and therapeutic drug response, evaluates the associations between efficacy and toxicity through analysis of drug metabolizing enzymes. As personalized medicine advances to the forefront of cancer care, pharmacogenomics can evaluate the individual’s ability to metabolize key medications in breast cancer treatment including anti-emetics, opioids, and tamoxifen. Women who do not achieve optimal levels of the active metabolites of tamoxifen are at higher risk of recurrence. Patients on chemotherapy who do not respond to anti-emetics can suffer from nausea and vomiting resulting in dehydration and hospitalization. This project evaluates the feasibility and therapeutic impact of real time pharmacogenomics in a selection of patients at the Inova Schar Cancer Institute (ISCI). Methods: An interdisciplinary team was created through the ISCI and the Inova Translational Medicine Institute to implement cheek swab based pharmacogenomic testing in 50 new patients undergoing mastectomy or neoadjuvant chemotherapy for breast cancer. Study patients were assessed for genotypic variability of key CYP enzymes and resulting impact on anti-emetic choices, perioperative pain control, and tamoxifen use. Results: Data was collected in a RedCap database. The 50 women enrolled were ages 28-83. Cheek swabs were performed in clinic and median turn around time was 7 days. 24 distinct genotypes were found in the 50 patients. 20% had abnormal CYP2D6 phenotypes indicating abnormalities in tamoxifen metabolism. 28% of patients had results leading to changes in dose or medication choice of perioperative pain control. 6% of patients had a CYP2D6 ultra-rapid metabolizer phenotype and were given granisetron in lieu of ondansetron. These patients had no documented nausea or vomiting requiring dose adjustments to the treatment plan or medical intervention. 40% of patients had results recommending avoidance of tamoxifen, 75% of which have ER+ breast cancer. 25% of patients had recommended changes to the dose of tamoxifen. Conclusions: Pharmacogenomic testing is feasible and available real-time for immediate use in the clinic. CYP mutations impact treatment decisions in a significant proportion of patients. Individualized treatment plans tailored to pharmacogenomic recommendations can be created in the multi-disciplinary setting and may decrease side effects of treatment and improve efficacy of curative therapy.

Innovations in Clinical Trial Design in the Era of Molecular Profiling

Historically, cancer has been studied, and therapeutic agents have been evaluated based on organ site, clinical staging, and histology. The science of molecular profiling has expanded our knowledge of cancer at the cellular and molecular level such that numerous subtypes are being described based on biomarker expression and genetic mutations rather than traditional classifications of the disease. Drug development has experienced a concomitant revolution in response to this knowledge with many new targeted therapeutic agents becoming available, and this has necessitated an evolution in clinical trial design. The traditional, large phase II and phase III adjuvant trial models need to be replaced with smaller, shorter, and more focused trials. These trials need to be more efficient and adaptive in order to quickly assess the efficacy of new agents and develop new companion diagnostics. We are now seeing a substantial shift from the traditional multiphase trial model to an increase in phase II adjuvant and neoadjuvant trials in earlier-stage disease incorporating surrogate endpoints for long-term survival to assess efficacy of therapeutic agents in shorter time frames. New trial designs have emerged with capabilities to assess more efficiently multiple disease types, multiple molecular subtypes, and multiple agents simultaneously, and regulatory agencies have responded by outlining new pathways for accelerated drug approval that can help bring effective targeted therapeutic agents to the clinic more quickly for patients in need.

Reduction of paclitaxel neuropathy with cryotherapy

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Background: Chemotherapy induced peripheral neuropathy (CIPN) is a common and potentially debilitating side effect of taxanes. Prior studies indicate weekly paclitaxel results in grade 2 or higher neuropathy in 25% of patients. Patients may experience persistent pain that impacts quality of life. Currently, there is little data that exists on effective therapies for prevention of paclitaxel neuropathy. This study investigates the efficacy and safety of cryotherapy for the prevention of paclitaxel-induced peripheral neuropathy. Methods: This is a single arm, phase II study of the effects of cryotherapy for breast cancer patients undergoing 12 cycles of weekly paclitaxel. Cryotherapy was administered by hypothermia mitts and slippers to patients’ hands and feet during, and 15 minutes before and after paclitaxel treatments. Neurologic assessments and neuropathy questionnaires were evaluated at baseline, every 4 cycles during treatment, and every 6 months follow up for two years. The primary objective is to assess if cryotherapy can decrease the rate of peripheral neuropathy. The primary efficacy endpoint is the rate of neuropathy in patients undergoing weekly paclitaxel treatments. Results: Between November 2014 and June 2015, 41 patients were enrolled in the study. Of 39 evaluable patients, 19 (48.7%) were without neurologic toxicity. 19 (48.7%) had grade 1 toxicity, paresthesia but without pain. Only one patient (2.6%) had grade 2 toxicity. Cryotherapy treatment was well tolerated; one patient could not participate due to cold intolerance. Conclusions: Cryotherapy reduced the incidence of pain and grade 2 or higher sensory neuropathy in patients receiving weekly paclitaxel. Clinical trial information: NCT02230319. [Table: see text]

Non-enzymatic, serum-free tissue culture of pre-invasive breast lesions for spontaneous generation of mammospheres

Breast ductal carcinoma in situ (DCIS), by definition, is proliferation of neoplastic epithelial cells within the confines of the breast duct, without breaching the collagenous basement membrane. While DCIS is a non-obligate precursor to invasive breast cancers, the molecular mechanisms and cell populations that permit progression to invasive cancer are not fully known. To determine if progenitor cells capable of invasion existed within the DCIS cell population, we developed a methodology for collecting and culturing sterile human breast tissue at the time of surgery, without enzymatic disruption of tissue. Sterile breast tissue containing ductal segments is harvested from surgically excised breast tissue following routine pathological examination. Tissue containing DCIS is placed in nutrient rich, antibiotic-containing, serum free medium, and transported to the tissue culture laboratory. The breast tissue is further dissected to isolate the calcified areas. Multiple breast tissue pieces (organoids) are placed in a minimal volume of serum free medium in a flask with a removable lid and cultured in a humidified CO₂ incubator. Epithelial and fibroblast cell populations emerge from the organoid after 10 - 14 days. Mammospheres spontaneously form on and around the epithelial cell monolayer. Specific cell populations can be harvested directly from the flask without disrupting neighboring cells. Our non-enzymatic tissue culture system reliably reveals cytogenetically abnormal, invasive progenitor cells from fresh human DCIS lesions.

Evaluation of autophagy as a therapeutic target for DCIS

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Background: Survival of intraductal, preinvasive proliferating cells under stress may promote genetic instability and the selection of invasive carcinoma cells. Our analysis of the mechanisms used by DCIS cells to survive in the hypoxic, nutrient deprived intraductal niche has revealed autophagy as a therapeutic target. Methods: DCIS spheroid forming cells have been isolated and propagated from fresh human DCIS lesions. We characterized the DCIS cells by organ culture, xenograft transplantation, molecular cytogenetics (300,000 SNPs) and 59 signal pathway profiling endpoints (Reverse Phase Protein Microarray [RPMA]). Results: DCIS spheroid forming cells were tumorigenic in xenograft models. Autophagy is up-regulated in: human DCIS lesions, DCIS spheroid-forming cells, and the xenograft tumors they generate. Autophagy is a means for intraductal neoplastic cells, accumulating in the duct, to digest intracellular contents and generate energy to survive in the face of severe metabolic, oxidative, and hypoxic stress. Suppression of autophagy by chloroquine kills human DCIS spheroid forming cells in culture and prevents them from forming tumors in xenografts (p < .0003). Based on these preclinical insights we have opened a neoadjuvant therapy trial for DCIS (NCT01023477 PINC Trial) to examine the safety and effectiveness of oral 30-day chloroquine for patients with any stage/grade DCIS. At the conclusion of treatment, all patients receive standard of care surgical therapy. MRI is performed before and after the treatment period. Endpoints compared before, versus after, therapy are lesion shrinkage, pathologic regression, disruption of lesion autophagy and proliferation (Ki67), induction of apoptosis, and suppression of xenograft tumorigenicity. Each patient serves as her own control because effectiveness is judged by comparing the patient’s DCIS lesion before and after oral therapy. Conclusions: We hypothesize that the intraductal pre-neoplastic cellular niche will be preferentially sensitive to a short term, anti-autophagy based prevention therapy which targets survival pathways used by pre-invasive carcinomas. Our unique trial design offers a means to functionally screen investigational agents that kill premalignant breast lesions.

Abstract 1265: Tissue is alive: Preserving phosphoproteins and tissue morphology in clinical trial samples

An urgent clinical goal is to identify subpopulations of cancer patients that may respond to targeted kinase inhibitors and/or their phosphorylated substrates. Consequently, phosphorylated signal pathway proteins have emerged as a critical class of analytes for therapeutic stratification. Technologies now exist that can measure protein phosphorylations and map cell signaling pathways in a single core-needle biopsy, thus relying on the inhibition of any kinase/phosphatase activity within the sample immediately following excision. Unfortunately applying these technologies to clinical samples has been hindered because phosphoprotein epitopes are not adequately preserved by formalin fixation and paraffin embedding, while freezing tissue samples may not be feasible in multi-center clinical trial sites and cannot adequately preserve morphology. To facilitate clinical trial molecular profiling, where immediate snap-freezing of tumor biopsies is not feasible, we have created a novel, one-step, room temperature preservative that stabilizes proteins/phosphoproteins equivalent to snap-freezing and tissue/cell morphology equivalent to neutral buffered formalin fixation. In addition, our preservative solution simultaneously fixes and decalcifies bony tissue, thus permitting molecular profiling of bony tissues that was never before possible. We have utilized our Biomarker and Histology Preservative (BHP-Cell and/or BHP-Tissue) in a breast cancer multi-site clinical trial (US Oncology 05-074/GSK LPT109096) and a clinical research multiple myeloma trial. BHP has been validated to a) function as a transport medium while preserving histomorphology, b) maintain full antigenicity for clinical immunohistochemistry (such as Ki-67, ER, PR, Her2, p63, and phosphorylated epitopes), c) preserve phosphoprotein epitopes for cell signaling pathway profiling by reverse phase protein microarray (RPMA), d) be compatible with frozen sections or paraffin embedding, and e) obviate the need for additional decalcification. Preservation of tissue morphology has been demonstrated in 25 mouse, feline, and human tissues with enhanced immunohistochemical properties for &gt;20 antigens using standard IHC protocols. RPMA data from LPT10906 shows differentially deranged signaling networks in the pre-treatment biopsies for patients that did not have a pathologic complete response compared to responders. Our multiple myeloma trial quantifies cell signaling pathway expression pre/post kinase inhibitor treatment, in an ex vivo treatment model, on both myeloma and bone marrow cells, preserved in BHP. We are currently evaluating the integrity of nucleic acid preservation in parallel with proteins to provide a universal one step biospecimen tissue fixative for clinical trials.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1265. doi:1538-7445.AM2012-1265

Clinical trial design in the age of molecular profiling

The accelerating science of molecular profiling has necessitated a rapid evolution in clinical trial design. Traditional clinical research begins with Phase I studies to characterize dose-limiting toxicities and defines maximally tolerated doses of drugs in small numbers of patients. Traditional Phase II studies test these drugs at the doses discovered during Phase I drug development in small numbers of patients evaluating efficacy and safety. Phase III studies test new therapies to demonstrate improved activity or improved tolerability compared with a standard of care regimen or a placebo. The rapid advances in the understanding of signal transduction, and the identification of new potential diagnostic and therapeutic targets, now require the design and implementation of molecular clinical trials that are very different than traditional Phase I, II, or III trials. The main differentiating factor is the use of a molecular end point to stratify a subset of patients to receive a specific treatment regimen. This chapter focuses on the issues surrounding (a) the definition of clinical end points and the assessment of tumor response; (b) clinical trial design models to define the targeted pathway; and (c) the need for appropriate biomarkers to monitor the response.

One-step preservation of phosphoproteins and tissue morphology at room temperature for diagnostic and research specimens

Background

There is an urgent need to measure phosphorylated cell signaling proteins in cancer tissue for the individualization of molecular targeted kinase inhibitor therapy. However, phosphoproteins fluctuate rapidly following tissue procurement. Snap-freezing preserves phosphoproteins, but is unavailable in most clinics and compromises diagnostic morphology. Formalin fixation preserves tissue histomorphology, but penetrates tissue slowly, and is unsuitable for stabilizing phosphoproteins. We originated and evaluated a novel one-step biomarker and histology preservative (BHP) chemistry that stabilizes signaling protein phosphorylation and retains formalin-like tissue histomorphology with equivalent immunohistochemistry in a single paraffin block.

Results

Total protein yield extracted from BHP-fixed, routine paraffin-embedded mouse liver was 100% compared to snap-frozen tissue. The abundance of 14 phosphorylated proteins was found to be stable over extended fixation times in BHP fixed paraffin embedded human colon mucosa. Compared to matched snap-frozen tissue, 8 phosphoproteins were equally preserved in mouse liver, while AMPKβ1 Ser108 was slightly elevated after BHP fixation. More than 25 tissues from mouse, cat and human specimens were evaluated for preservation of histomorphology. Selected tissues were evaluated in a multi-site, independent pathology review. Tissue fixed with BHP showed equivalent preservation of cytoplasmic and membrane cytomorphology, with significantly better nuclear chromatin preservation by BHP compared to formalin. Immunohistochemical staining of 13 non-phosphorylated proteins, including estrogen receptor alpha, progesterone receptor, Ki-67 and Her2, was equal to or stronger in BHP compared to formalin. BHP demonstrated significantly improved immunohistochemical detection of phosphorylated proteins ERK Thr202/Tyr204, GSK3-α/β Ser21/Ser9, p38-MAPK Thr180/Tyr182, eIF4G Ser1108 and Acetyl-CoA Carboxylase Ser79.

Conclusion

In a single paraffin block BHP preserved the phosphorylation state of several signaling proteins at a level comparable to snap-freezing, while maintaining the full diagnostic immunohistochemical and histomorphologic detail of formalin fixation. This new tissue fixative has the potential to greatly facilitate personalized medicine, biobanking, and phospho-proteomic research.

Breast cancer stem cells: a new target for therapy

Normal adult tissue stem cells awake from a dormant state to grow, differentiate, and regenerate damaged tissue. They also travel in the circulation and colonize distant organs at sites undergoing tissue repair. These same traits are utilized or co-opted by metastatic cancer cells. The cancer stem cell theory proposes that tumors emerge from a subpopulation of cancer cells that possess stem cell properties. This theory has profound implications for therapy. A small number of cancer stem cells may lie dormant following conventional therapy and tumor remission, only to re-emerge and regenerate the entire recurrent cancer. Consequently, it has been proposed that targeting cancer stem cells is the only way to obtain durable cancer treatment responses. Several strategies for targeting cancer stem cells have been proposed. Nevertheless, a number of issues must be investigated and resolved before effective treatments targeting cancer stem cells can enter clinical testing.

A portrait of tissue phosphoprotein stability in the clinical tissue procurement process

Little is known about the preanalytical fluctuations of phosphoproteins during tissue procurement for molecular profiling. This information is crucial to establish guidelines for the reliable measurement of these analytes. To develop phosphoprotein profiles of tissue subjected to the trauma of excision, we measured the fidelity of 53 signal pathway phosphoproteins over time in tissue specimens procured in a community clinical practice. This information provides strategies for potential surrogate markers of stability and the design of phosphoprotein preservative/fixation solutions. Eleven different specimen collection time course experiments revealed augmentation (+/-20% from the time 0 sample) of signal pathway phosphoprotein levels as well as decreases over time independent of tissue type, post-translational modification, and protein subcellular location (tissues included breast, colon, lung, ovary, and uterus (endometrium/myometrium) and metastatic melanoma). Comparison across tissue specimens showed an >20% decrease of protein kinase B (AKT) Ser-473 (p < 0.002) and myristoylated alanine-rich C-kinase substrate protein Ser-152/156 (p < 0.0001) within the first 90-min postexcision. Proteins in apoptotic (cleaved caspase-3 Asp-175 (p < 0.001)), proliferation/survival/hypoxia (IRS-1 Ser-612 (p < 0.0003), AMP-activated protein kinase beta Ser-108 (p < 0.005), ERK Thr-202/Tyr-204 (p < 0.003), and GSK3alphabeta Ser-21/9 (p < 0.01)), and transcription factor pathways (STAT1 Tyr-701 (p < 0.005) and cAMP response element-binding protein Ser-133 (p < 0.01)) showed >20% increases within 90-min postprocurement. Endothelial nitric-oxide synthase Ser-1177 did not change over the time period evaluated with breast or leiomyoma tissue. Treatment with phosphatase or kinase inhibitors alone revealed that tissue kinase pathways are active ex vivo. Combinations of kinase and phosphatase inhibitors appeared to stabilize proteins that exhibited increases in the presence of phosphatase inhibitors alone (ATF-2 Thr-71, SAPK/JNK Thr-183/Tyr-185, STAT1 Tyr-701, JAK1 Tyr-1022/1023, and PAK1/PAK2 Ser-199/204/192/197). This time course study 1) establishes the dynamic nature of specific phosphoproteins in excised tissue, 2) demonstrates augmented phosphorylation in the presence of phosphatase inhibitors, 3) shows that kinase inhibitors block the upsurge in phosphorylation of phosphoproteins, 4) provides a rational strategy for room temperature preservation of proteins, and 5) constitutes a foundation for developing evidence-based tissue procurement guidelines.

Development of reverse phase protein microarrays for clinical applications and patient-tailored therapy

While genomics provide important information about the somatic genetic changes, and RNA transcript profiling can reveal important expression changes that correlate with outcome and response to therapy, it is the proteins that do the work in the cell. At a functional level, derangements within the proteome, driven by post-translational and epigenetic modifications, such as phosphorylation, is the cause of a vast majority of human diseases. Cancer, for instance, is a manifestation of deranged cellular protein molecular networks and cell signaling pathways that are based on genetic changes at the DNA level. Importantly, the protein pathways contain the drug targets in signaling networks that govern overall cellular survival, proliferation, invasion and cell death. Consequently, the promise of proteomics resides in the ability to extend analysis beyond correlation to causality. A critical gap in the information knowledge base of molecular profiling is an understanding of the ongoing activity of protein signaling in human tissue: what is activated and "in use" within the human body at any given point in time. To address this gap, we have invented a new technology, called reverse phase protein microarrays, that can generate a functional read-out of cell signaling networks or pathways for an individual patient obtained directly from a biopsy specimen. This "wiring diagram" can serve as the basis for both, selection of a therapy and patient stratification.

Technology insight: pharmacoproteomics for cancer--promises of patient-tailored medicine using protein microarrays

Patient-tailored medicine can be defined as the selection of specific therapeutics to treat disease in a particular individual based on genetic, genomic or proteomic information. While individualized treatments have been used in medicine for years, advances in cancer treatment have now generated a need to more precisely define and identify those patients who will derive the most benefit from new-targeted agents. Cellular signaling pathways are a protein-based network, and the intended drug effect is to disrupt aberrant protein phosphorylation-based enzymatic activity and epigenetic phenomena. Pharmacoproteomics, or the tailoring of therapy based on proteomic knowledge, will begin to take a central role in this process. A new type of protein array platform, the reverse-phase protein microarray, shows potential for providing detailed information about the state of the cellular 'circuitry' from small samples such as patient biopsy specimens. Measurements of hundreds of specific phosphorylated proteins that span large classes of important signaling pathways can be obtained at once from only a few thousand cells. Clinical implementation of these new proteomic tools to aid the clinical, medical and surgical oncologist in making decisions about patient care will now require thoughtful communication between practicing clinicians and research scientists.

Carcinoembryonic antigen induction of IL-10 and IL-6 inhibits hepatic ischemic/reperfusion injury to colorectal carcinoma cells

Tumor cells cause ischemia/reperfusion (I/R) injury as they arrest within the hepatic microvasculature with the production of nitric oxide (NO) and reactive oxygen species (ROS) that kill both host liver and implanting tumor cells. Carcinoembryonic antigen (CEA) both facilitates the survival of experimental metastasis to nude mouse liver by weakly metastatic human colorectal carcinomas (CRCs) and induces the release of the proinflammatory cytokine IL-6. We hypothesized that CEA also stimulates the release of the antiinflammatory cytokine IL-10 causing inhibition of the toxicity of hepatic I/R injury and indirect stimulation of tumor cell colonization of the liver. Intravenous injection of CEA produced more than 1 ng/ml of IL-10 in the systemic circulation within 1 hr which subsided by 8 hr. The IL-10 response is specific to CEA since the pentapeptide sequence in CEA that binds to the CEA receptor stimulated isolated Kupffer cells to produce IL-10. IL-10, but not IL-6, increased the survival of weakly metastatic CRC cocultured with ischemic-reoxygenated liver fragments but did not affect the survival of CRC exposed to oxidative stress in the absence of any host cells. CEA, IL-6 and IL-10 pretreatment reduced expression of iNOS but only CEA and IL-10 strongly inhibited NO and total reactive species production by ischemic-rexoygenated liver. IL-6 was toxic to CRC exposed to oxidative stress while IL-10 did not have a direct effect on CRC. Thus, CEA stimulates production of IL-10 that may enhance metastasis by promoting the ability of circulating CRC cells to survive the I/R injury of implantation.

Carcinoembryonic antigen facilitates experimental metastasis through a mechanism that does not involve adhesion to liver cells

Carcinoembryonic antigen (CEA) injected intravenously into athymic nude mice increases the ability of weakly metastatic human colorectal carcinoma (CRC) cells to colonize liver in an experimental metastasis assay. Since CEA acts as an intercellular adhesion molecule in vitro, several investigators have postulated that this facilitation of experimental metastasis may be mediated through adhesion between CEA on CRC and CEA-binding proteins on Kupffer or other cells lining the hepatic sinusoid. The present work tested this postulate both by intravital fluorescence videomicroscopy in vivo and in adhesion assays in vitro to enriched populations of Kupffer cells and hepatic sinusoidal endothelial cells (SEC). The data indicate that CEA expression does not effect adhesion to enriched Kupffer cells or SEC in vitro. These data suggest that CEA enhances liver colonization through another mechanism, possibly one that involves modulation of the hepatic response to tumor cell implantation.

Reactive nitrogen and oxygen radicals formed during hepatic ischemia-reperfusion kill weakly metastatic colorectal cancer cells

Microscopic infarcts develop within the livers of athymic nude mice during the first 24 h after human colorectal carcinoma (CRC) cells arrest within hepatic sinusoids. Because these regions are reperfused, essentially all weakly metastatic clone A and MIP-101 CRC cells die, whereas many highly metastatic CX-1 CRC cells survive. Because hepatic sinusoidal endothelial cells kill tumor cells in vitro by producing nitric oxide, superoxide anion, and other reactive oxygen and nitrogen species, our purpose was to determine whether reoxygenation of ischemic hepatic cultures in vitro forms toxic oxygen and nitrogen radicals that kill weakly but not highly metastatic CRC cells. CRC cells (10(7)) were labeled with rhodamine-dextran and calcein AM, cultured with cells from one mouse liver in a rotating suspension culture system for up to 24 h, and the metabolic activity of the CRC cells was determined. Liver fragments oxygenated normally before harvest were not toxic to either CRC cell line, but coculture with liver made ischemic by a 3-min ligation of the portal vein and hepatic artery in vivo before harvest and then cultured in oxygenated medium killed 50-70% of weakly metastatic clone A and MIP-101 cells at 24 h but <15% of highly metastatic CX-1 cells. Inhibition of nitric oxide synthase, addition of exogenous superoxide dismutase, but not catalase or hypoxia, during coculture blocked the killing of weakly metastatic CRC cells. Thus, reoxygenation of hepatic parenchymal and nonparenchymal cells after ischemia may form toxic species that eliminate weakly metastatic CRCs within 24 h of their arrest in the liver.

Role of nitric oxide and superoxide anion in elimination of low metastatic human colorectal carcinomas by unstimulated hepatic sinusoidal endothelial cells

Human colorectal carcinoma (CRC) cell survival for the first 24 h after implantation in the hepatic sinusoid determines its potential to colonize the liver. Nearly 10-fold more highly metastatic CX-1 cells survive within the livers of nude mice 24 h after intrasplenic injection than weakly metastatic clone A cells. Because CRCs contact sinusoidal endothelial cells (SECs) during implantation, we sought to determine whether SECs were more toxic to clone A than to CX-1 cells. When 2 x 10(4) vital dye-labeled CRC cells were added to murine SEC monolayers, more than 30% of clone A cells lost calcein AM fluorescence compared to fewer than 5% of CX-1 cells after 24 h of coculture with SECs. Kupffer cells did not mediate this effect, because neither enriched Kupffer cells nor SECs treated with a Kupffer cell inhibitor altered the SEC-mediated toxic effect to clone A cells. Pretreatment with a nitric oxide synthase inhibitor, N(G)-monomethyl-L-arginine, superoxide dismutase, or dexamethasone, blocked SEC-mediated toxicity to clone A cells, whereas calcium chelation and catalase did not. In addition, clone A cells were more sensitive to a superoxide donor, 3-morpholinosydnonimine N-ethylcarbamide, than were CX-1 cells, and neither cell line was sensitive to sodium nitroprusside, a nitric oxide donor. Thus, unstimulated murine SECs produce reactive oxygen species that are selectively toxic to weakly metastatic clone A cells. This may be a mechanism by which host liver cells eliminate weakly metastatic neoplastic cells.

In vivo induction of murine cytokine production by carcinoembryonic antigen

Carcinoembryonic antigen (CEA) may promote experimental metastasis through production of cytokines. The effect of systemic CEA on the production of proinflammatory cytokines was investigated in mice and compared to levels induced by lipopolysaccharide (LPS). Serum concentrations of interleukin (IL)-6 peaked 1 h after an i.v. CEA injection of 40 microg/mouse to 37-54% of the maximal level induced by a 1 microg/mouse injection of LPS in both normal and immunoincompetent mice. The CEA induction of IL-6 was a specific response, because the peptide PELPK (the pentapeptide on CEA that is the ligand for the CEA receptor on Kupffer cells) conjugated to albumin induced 30% of the maximal CEA response for IL-6, whereas the specificity control PELGK-conjugated albumin did not. IL-1alpha and tumor necrosis factor (TNF)-alpha levels after i.v. injection of CEA were only 3-5% of those induced by LPS. The IL-6 responses of mice pretreated with 100 microg/kg genistein were decreased by more than 40%. However, genistein inhibited the TNF-alpha response to LPS by 46% but increased the CEA-induced response by 300%. When murine Kupffer cells were stimulated with LPS or CEA in vitro, LPS increased tyrosine phosphorylation of a Mr 30,000 protein, whereas CEA decreased phosphorylation of a Mr 60,000 protein and did not increase phosphorylation of the Mr 30,000 protein. Thus, i.v. CEA stimulates production of IL-6 and TNF-alpha after binding to Kupffer cells through signal transduction pathways that appear to be different from those stimulated by LPS.