Assessment of biological organ age using molecular pathology in pre-transplant kidney biopsies.

Organ shortage is a major challenge in kidney transplantation but the use of older donors, often with co-morbidities, is hampered by inconsistent outcomes. Methods of accurately stratifying marginal donor organs by clinical and histological assessment are lacking. To better understand organ variability, we profiled the transcriptomes of 271 kidneys from deceased donors at retrieval. Following correction for biopsy composition, we assessed molecular pathways that associated with delayed, and sub-optimal one-year graft function. Analysis of cortical biopsies identified an adaptive immune gene-rich module that significantly associated with increasing age and worse outcomes. Cellular deconvolution using human kidney reference single cell transcriptomes confirmed an increase in kidney-specific B and T cell signatures, as well as kidney macrophage, myofibroblast and fibroblast gene sets in this module. Surprisingly, innate immune pathway and neutrophil gene signature enrichment was associated with better outcomes. Thus, our work uncovers cellular molecular features of pathological organ ageing, identifiable at kidney retrieval, with translational potential.

What dietary interventions have been tested in heart failure with preserved ejection fraction? A systematic scoping review.

AIMS: To determine what dietary interventions have been tested in heart failure with preserved ejection fraction (HFpEF), the modulation method, and outcomes employed and to summarize any evidence for benefit. METHODS AND RESULTS: We performed key word searches in five bibliographic databases from 2001 to 2021, to identify randomized or experimental dietary interventions tested in HFpEF or mixed heart failure (HF) samples. Study characteristics were summarized according to population, intervention, comparator, outcome categories and intervention complexity was assessed. Twenty-five clinical investigations were retrieved; only 10 (40%) were conducted exclusively in HFpEF; the remainder enrolled mixed HF samples. Most studies employed either highly tailored prescribed diets (n = 12, 48%) or dietary supplementation (n = 10, 40%) modalities. Dietary pattern interventions (n = 3, 12%) are less well represented in the literature. CONCLUSION: Heterogeneity made pooling studies challenging. Better reporting of baseline characteristics and the use of standardized HF lexicon would ensure greater confidence in interpretation of studies involving mixed HF populations. The field would benefit greatly from explicit reporting of the biological mechanism of action (e.g. the causal pathway) that an intervention is designed to modulate so that studies can be synthesized via their underlying mechanism of action by which diet may affect HF. An extension of the current set of core outcomes proposed by the European Society of Cardiology Heart Failure Association would ensure dietary clinical endpoints are more consistently defined and measured. REGISTRATION: PROSPERO: CRD42019145388.

Sustained Inflammation of Breast Tumors after Needle Biopsy.

INTRODUCTION: Needle biopsy is essential for definitive diagnosis of breast malignancy. Significant histologic changes due to tissue damage have been reported in solid tumors. This study investigated the association between time from needle biopsy and inflammation in breast tumors. METHODS: A total of 73 stage I-II invasive breast cancer cases diagnosed by image-guided needle biopsy who had surgery as their first definitive treatment were retrospectively analyzed. Time from biopsy to surgical excision ranged from 8 to 252 days. Histological sections of surgically resected tumors with a visible needle tract were reviewed by histologic evaluation. Data were analyzed by McNemar's test for proportional differences, and the Benjamini-Hochberg procedure was used to assess the association between immune cell prevalence and clinical variables. RESULTS: Characteristic histology changes, including foreign body giant-cell reaction, synovial-cell metaplasia, desmoplastic repair changes, granulation tissue, fat necrosis, and inflammation, were frequently detected adjacent to the needle tract. Spatial comparison indicated that a higher proportion of cases had neutrophils, eosinophils, and macrophages adjacent to the needle tract than tumors distant from it. The presence of inflammatory cells adjacent to the needle tract was not associated with time from biopsy or subtype. Still, plasma cells were associated with residual carrier material from biopsy markers. CONCLUSION: Macrophages and eosinophils are highly abundant and retained adjacent to the needle tract regardless of time from the biopsy.

What are the outcomes of dietary interventions in Heart Failure with preserved Ejection Fraction? A systematic review and meta-analysis.

AIMS: To determine the efficacy of dietary interventions in Heart Failure with preserved Ejection Fraction (HFpEF). METHOD AND RESULTS: Keyword searches were performed in five bibliographic databases to identify randomized or controlled studies of dietary interventions conducted in HFpEF or mixed heart failure (HF) samples published in the English language. Studies were appraised for bias and synthesized into seven categories based on the similarity of the intervention or targeted population. The quality of the body of evidence was assessed via the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) framework. Twenty-five unique interventions were identified; 17 were considered for meta-analysis. Most studies were judged to be at high risk of bias. There was moderate-quality evidence that caloric restriction led to clinically meaningful improvements in blood pressure and body weight. There was moderate-quality evidence that carbohydrate restriction resulted in meaningful reductions in blood pressure. There was very low-quality evidence that protein supplementation improved blood pressure and body weight and moderate-quality evidence for clinically meaningful improvements in function. CONCLUSIONS: While some types of dietary interventions appeared to deliver clinically meaningful change in critical outcomes; the study heterogeneity and overall quality of the evidence make it difficult to make firm recommendations. Greater transparency when reporting the nutritional composition of interventions would enhance the ability to pool studies. REGISTRATION: PROSPERO CRD42019145388.

Using Fourier ptychography microscopy to achieve high-resolution chromosome imaging: an initial evaluation.

SIGNIFICANCE: Searching analyzable metaphase chromosomes is a critical step for the diagnosis and treatment of leukemia patients, and the searching efficiency is limited by the difficulty that the conventional microscopic systems have in simultaneously achieving high resolution and a large field of view (FOV). However, this challenge can be addressed by Fourier ptychography microscopy (FPM) technology. AIM: The purpose of this study is to investigate the feasibility of utilizing FPM to reconstruct high-resolution chromosome images. APPROACH: An experimental FPM prototype, which was equipped with 4 × / 0.1 NA or 10 × / 0.25 NA objective lenses to achieve a theoretical equivalent NA of 0.48 and 0.63, respectively, was developed. Under these configurations, we first generated the system modulation transfer function (MTF) curves to assess the resolving power. Next, a group of analyzable metaphase chromosomes were imaged by the FPM system, which were acquired from the peripheral blood samples of the leukemia patients. The chromosome feature qualities were evaluated and compared with the results accomplished by the corresponding conventional microscopes. RESULTS: The MTF curve results indicate that the resolving power of the 4 × / 0.1 NA FPM system is equivalent and comparable to the 20 × / 0.4 NA conventional microscope, whereas the performance of the 10 × / 0.25 NA FPM system is close to the 60 × / 0.95 NA conventional microscope. When imaging the chromosomes, the feature qualities of the 4 × / 0.1 NA FPM system are comparable to the results under the conventional 20 × / 0.4 NA lens, whereas the feature qualities of the 10 × / 0.25 NA FPM system are better than the conventional 60 × / 0.95 NA lens and comparable to the conventional 100 × / 1.25 NA lens. CONCLUSIONS: This study initially verified that it is feasible to utilize FPM to develop a high-resolution and wide-field chromosome sample scanner.

Mandibular swelling as the initial presentation for renal cell carcinoma: A case report.

INTRODUCTION: Renal cell carcinoma (RCC) is the most common malignant tumour of the kidney. It usually presents in an occult manner, rarely with the classical triad of haematuria, abdominal mass and abdominal pain. Up to a third of patients have metastasis on presentation and only a few case reports have involved the mandible. PRESENTATION OF CASE: We present the case of a renal cell carcinoma that presented, in a 56-year-old lady, with mandibular swelling as its main clinical manifestation. This patient presented with a 3-month history of right sided facial swelling, associated with pain and intermittent paraesthesia to the right side of the tongue and lower lip. Imaging of the mandible revealed a lesion that had caused complete destruction of the right condyle, coronoid and ramus. Ultrasound guided biopsy revealed the nature of the mass to be metastatic renal cell carcinoma. Subsequent computed tomography (CT) imaging of the abdomen and pelvis confirmed the presence of a tumour in the right kidney. Due to the advanced nature of the disease, radical treatment was not suitable, and the patient passed away 11 months after diagnosis with palliative care. DISCUSSION AND CONCLUSION: Whilst mandibular swelling is usually benign, it should be kept in mind that orofacial symptoms can be the initial presentation of systemic disease. Persistent swellings with infection ruled out, or those causing cranial nerve palsy, should be investigated further.

Functional Blockade of E-Selectin in Tumor-Associated Vessels Enhances Anti-Tumor Effect of Doxorubicin in Breast Cancer.

Chemotherapy is a mainstay of treatment for solid tumors. However, little is known about how therapy-induced immune cell infiltration may affect therapy response. We found substantial CD45+ immune cell density adjacent to E-selectin expressing inflamed vessels in doxorubicin (DOX)-treated residual human breast tumors. While CD45 level was significantly elevated in DOX-treated wildtype mice, it remained unchanged in DOX-treated tumors from E-selectin null mice. Similarly, intravenous administration of anti-E-selectin aptamer (ESTA) resulted in a significant reduction in CD45+ immune cell density in DOX-treated residual tumors, which coincided with a delay in tumor growth and lung metastasis in MMTV-pyMT mice. Additionally, both tumor infiltrating T-lymphocytes and tumor associated-macrophages were skewed towards TH2 in DOX-treated residual breast tumors; however, ESTA suppressed these changes. This study suggests that DOX treatment instigates de novo intratumoral infiltration of immune cells through E-selectin, and functional blockade of E-selectin may reduce residual tumor burden as well as metastasis through suppression of TH2 shift.

Decidualized Stroma in Pelvic Lymph Nodes in a Pregnant Patient With Cervical Squamous Cell Carcinoma: A Case Report.

Decidualized endometrial stroma is an uncommon finding in lymph nodes but is typically found in the setting of endometriosis where endometrial glands give a hint toward the diagnosis. On the other hand, endometrial stroma with no identifiable endometrial glands can be challenging to differentiate from metastatic squamous cell carcinoma. We report a case of a 22-year-old female who presented to our medical center as a known case of cervical squamous cell carcinoma. The patient desired future fertility and became pregnant. She was treated during her second trimester and underwent a radical cesarean hysterectomy at 37 weeks' gestation with bilateral pelvic lymph node dissection. Resection showed residual moderately differentiated squamous cell carcinoma of the cervix with lymphovascular invasion. Two pelvic lymph nodes were found to have decidualized stroma. Immunohistochemistry was done to rule out metastasis and no metastatic carcinoma was identified in any of the lymph nodes. It is necessary to be aware of the possibility of decidualized stromal changes in pelvic lymph nodes to avoid misdiagnosis.

miR-23b and miR-27b are oncogenic microRNAs in breast cancer: evidence from a CRISPR/Cas9 deletion study.

BACKGROUND: Altered expression of microRNAs (miRNAs) is known to contribute to cancer progression. miR-23b and miR-27b, encoded within the same miRNA cluster, are reported to have both tumor suppressive and oncogenic activity across human cancers, including breast cancer. METHODS: To clarify this dichotomous role in breast cancer, miR-23b and miR-27b were knocked out using CRISPR/Cas9 gene knockout technology, and the role of endogenous miR-23b and miR-27b was examined in a breast cancer model system in vitro and in vivo. RESULTS: Characterization of the knockout cells in vitro demonstrated that miR-23b and miR-27b are indeed oncogenic miRNAs in MCF7 breast cancer cells. miR-23b and miR-27b knockout reduced tumor growth in xenograft nude mice fed a standard diet, supporting their oncogenic role in vivo. However, when xenograft mice were provided a fish-oil diet, miR-27b depletion, but not miR-23b depletion, compromised fish-oil-induced suppression of xenograft growth, indicating a context-dependent nature of miR-27b oncogenic activity. CONCLUSIONS: Our results demonstrate that miR-23b and miR-27b are primarily oncogenic in MCF7 breast cancer cells and that miR-27b may have tumor suppressive activity under certain circumstances.

Cytologic patterns of cervical adenocarcinomas with emphasis on factors associated with underdiagnosis.

BACKGROUND: New cervical cancers continue to be diagnosed despite the success of Papanicolaou (Pap) tests. In an effort to identify pitfalls that limit the diagnosis of adenocarcinoma, the authors reviewed the cytologic characteristics of endocervical adenocarcinomas in their patient population. METHODS: Liquid-based cytology slides from 45 women who had concurrent, histologically confirmed cervical adenocarcinomas were reviewed retrospectively and semiquantitatively for 25 key cytologic traits. The original sign-out diagnosis, available clinical findings, and high-risk human papillomavirus (HR HPV) results also were noted. RESULTS: Abundant tumor cellularity, nuclear size from 3 to 6 times normal, abundant 3-dimensional tumor cell groups, round cell shape, and cytoplasmic neutrophils characterized the 23 cases that were identified correctly as adenocarcinomas. Key reasons for undercalls included low tumor cellularity and low-grade columnar morphology; these also tended to correlate with low-grade or unusual adenocarcinoma variants on histology. Overall, 73% of adenocarcinomas had a concurrent positive HR HPV test. CONCLUSIONS: Most endocervical adenocarcinomas can be diagnosed accurately in cases with classical features, but some cases continue to be problematic when evaluated based on cytologic features alone. Reflex HPV testing may help increase Pap test sensitivity for challenging cases that have atypical glandular cells of undetermined significance. Occasional cases with negative HR HPV test results remain of concern.

Inhibition of BMI1, a Therapeutic Approach in Endometrial Cancer.

With rising incidence rates, endometrial cancer is one of the most common gynecologic malignancies in the United States. Although surgery provides significant survival benefit to early-stage patients, those with advanced or recurrent metastatic disease have a dismal prognosis. Limited treatment options include chemotherapy and radiotherapy. Hence, there is a compelling need for developing molecularly targeted therapy. Here, we show that the polycomb ring finger protein BMI1, also known as a stem cell factor, is significantly overexpressed in endometrial cancer cell lines, endometrial cancer patient tissues as well as in nonendometrioid histologies and associated with poor overall survival. PTC-028, a second-generation inhibitor of BMI1 function, decreases invasion of endometrial cancer cells and potentiates caspase-dependent apoptosis, while normal cells with minimal expression of BMI1 remain unaffected. In an aggressive uterine carcinosarcoma xenograft model, single-agent PTC-028 significantly delayed tumor growth and increased tumor doubling time compared with the standard carboplatin/paclitaxel therapy. Therefore, anti-BMI1 strategies may represent a promising targeted approach in patients with advanced or recurrent endometrial cancer, a population where treatment options are limited. Mol Cancer Ther; 17(10); 2136-43. ©2018 AACR.

Classification of Tumor Epithelium and Stroma by Exploiting Image Features Learned by Deep Convolutional Neural Networks.

The tumor-stroma ratio (TSR) reflected on hematoxylin and eosin (H&E)-stained histological images is a potential prognostic factor for survival. Automatic image processing techniques that allow for high-throughput and precise discrimination of tumor epithelium and stroma are required to elevate the prognostic significance of the TSR. As a variant of deep learning techniques, transfer learning leverages nature-images features learned by deep convolutional neural networks (CNNs) to relieve the requirement of deep CNNs for immense sample size when handling biomedical classification problems. Herein we studied different transfer learning strategies for accurately distinguishing epithelial and stromal regions of H&E-stained histological images acquired from either breast or ovarian cancer tissue. We compared the performance of important deep CNNs as either a feature extractor or as an architecture for fine-tuning with target images. Moreover, we addressed the current contradictory issue about whether the higher-level features would generalize worse than lower-level ones because they are more specific to the source-image domain. Under our experimental setting, the transfer learning approach achieved an accuracy of 90.2 (vs. 91.1 for fine tuning) with GoogLeNet, suggesting the feasibility of using it in assisting pathology-based binary classification problems. Our results also show that the superiority of the lower-level or the higher-level features over the other ones was determined by the architecture of deep CNNs.

Circulating Tumor Cells Accurately Predicting Progressive Disease After Treatment in a Patient with Non-small Cell Lung Cancer Showing Response on Scans.

Lung cancer is the leading cause of cancer-related deaths worldwide. Most patients present with advanced inoperable disease. Traditionally, responses to treatments are evaluated using different imaging modalities, which can sometimes be confusing. This is particularly more relevant in stage 3 disease where, after radiation therapy, persistent tumors on scans can represent active disease or scar tissue. We have been evaluating role of circulating tumor cells (CTCs) in that setting. Here we present the case of a 68-year-old male with stage 3 disease whose primary tumor responded to chemoradiotherapy on imaging, but whose CTC count was higher than the pre-treatment value. The patient later developed liver metastases. In this case, the CTC count more accurately predicted the patient's prognosis and highlights the need for exploration of the CTC count as a tool supplemental to imaging modalities.

Pathologic evaluation of tumor-associated macrophage density and vessel inflammation in invasive breast carcinomas.

Tumor-associated macrophages (TAMs) are major constituents of the tumor microenvironment in solid tumors and have been implicated as mediators of tumor progression, invasion and metastasis. Correspondingly, accumulation of TAMs is associated with unfavorable clinical outcomes in numerous types of solid tumors. E-selectin is a hallmark of inflammation and a key adhesion molecule that accommodates the initial contact of circulating immune cells with the inflamed vessel surface. Currently, the association between E-selectin and TAMs is not fully elucidated; therefore, the present study investigated the association between vessel inflammation, TAM infiltration, and clinical outcome in breast cancer. A total of 53 procedure-naïve invasive breast cancer cases were immunohistochemically analyzed for the presence of cluster of differentiation (CD)68+ TAMs, E-selectin+ vessels and tumor inflammation. The association between CD68 and E-selectin expression, and tumor inflammation as well as overall survival was evaluated using Kaplan-Meier survival curves and multivariable Cox's proportional hazards regression analysis. The abundance of TAMs was identified to be positively associated with tumor inflammation, estrogen receptor and E-selectin expression levels. A greater prevalence of TAMs and tumor inflammation was significantly associated with shorter overall survival times. E-selectin expression levels were significantly higher in tumor vessels among elderly patients, but were not associated with overall survival. The abundance of TAMs was associated with the presence of E-selectin-expressing inflamed tumor vessels and tumor inflammation, as well as overall survival in patients with invasive breast carcinoma.

Docosahexaenoic acid and disulfiram act in concert to kill cancer cells: a mutual enhancement of their anticancer actions.

We previously reported a synergistic anticancer action of clioquinol and docosahexaenoic acid (DHA) in human cancer cells. However, clioquinol has been banned from the clinic due to its neurotoxicity. This study identified disulfiram (DSF) as a substitute compound to clioquinol, acting in concert with DHA to more effectively kill cancer cells and suppress tumor growth. Treatment with DSF and DHA induced greater apoptotic cell death and suppression of tumor growth in vitro and in vivo, as compared to DSF and DHA used alone. Mechanistic studies demonstrated that DSF enhances DHA-induced cellular oxidative stress as evidenced by up-regulation of Nrf2-mediated heme oxygenase 1 (HO-1) gene transcription. On the other hand, DHA was found to enhance DSF-induced suppression of mammosphere formation and stem cell frequency in a selected cancer model system, indicating that alterations to cancer cell stemness are involved in the combinatory anticancer action of DSF and DHA. Thus, DHA and DSF, both clinically approved drugs, act in concert to more effectively kill cancer cells. This combinatory action involves an enhancement of cellular oxidative stress and suppression of cancer cell stemness.

Distribution of cell types differs in Papanicolaou tests of squamous cell carcinomas and adenocarcinomas.

INTRODUCTION: Successful cervical cancer screening has led to decreasing numbers of malignant Papanicolaou tests in most laboratories. A previous study demonstrated a greater trend to unsatisfactory Papanicolaou tests in women with squamous carcinoma when compared with adenocarcinoma cases. However, adenocarcinomas were less frequently recognized as malignant. MATERIALS AND METHODS: In an effort to elucidate differences in Papanicolaou tests from these tumor types, the relative distribution of cells was blindly and semi-quantitatively assessed in ThinPrep Papanicolaou slides from 332 women with biopsy-proven squamous carcinoma (237 cases), adenocarcinoma (45), and noninvasive lesions (50). RESULTS: Significant differences (P < 0.0001) among the three categories were observed in total cellularity, amount of blood and diathesis, normal endocervical cells, and normal squamous cells. When slides from squamous carcinomas and adenocarcinomas were compared, the amount of blood (P < 0.4) and presence of diathesis (P > 0.004) were more prominent in squamous carcinomas. The number of endocervical cells (P < 0.0001) was greater in adenocarcinomas, but adenocarcinomas were less likely to be recognized as malignant. CONCLUSIONS: This systematic evaluation reinforces earlier suggestions that the presence of blood and tumor diathesis allow easier recognition of squamous carcinoma. A more detailed analysis of adenocarcinoma's cellular characteristics in Papanicolaou tests is needed to understand the reasons for undercalls in this tumor type.

E-selectin Targeting PEGylated-thioaptamer Prevents Breast Cancer Metastases.

E-selectin is an adhesion molecule expressed on the luminal surface of inflamed blood vessels that mediates hematogenous metastasis by assisting shear-resistant adhesion of circulating tumor cells to the vessel surface under dynamic blood flow. Previously, we developed an E-selectin antagonistic thioaptamer (ESTA) for the prevention of hematogenous metastasis through the blockade of CD44high breast cancer cells (BCa) adhesion to E-selectin-expressing premetastatic endothelial niche. The current study focuses on developing a PEGylated E-selectin targeting thioaptamer with improved pharmaceutical properties. A serial deletion of stem-loops reveled that loop-1 and -2 (ESTA7) are the minimally effective backbone structure necessary to obtain inhibition of the E-selectin/CD44 interaction and shear resistant adhesion of CD44high BCa to E-selectin-expressing human endothelial cells (HMVECs) at a level equal to ESTA. Chemical conjugation of methoxy-polyethylene-glycol (PEG) at the sizes of 5 and 10 kDa did not interfere with ESTA7-mediated shear-resistant adhesion. However, in vivo study demonstrated that only 10 kDa PEG-conjugated ESTA7 (ESTA7-p10) retains the activity to inhibit metastases at a level equal to parental ESTA. Additionally, a single intravenous injection of ESTA7-p10 inhibited the development of lung, brain, and bone metastases of MDA-MB-231, through the blockade of E-selectin. Moreover, PEGylation led to an extension of elimination half-life and increase of AUC, resulting in superior inhibition of metastasis development compared to parental ESTA with a longer interval between dosing in a spontaneous metastasis model. Lastly, repeated intravenous administration of ESTA7-p10 was tolerated in mice, highlighting the potential prophylactic application of ESTA7-p10 for metastasis prevention.

FaceTime validation study: Low-cost streaming video for cytology adequacy assessment.

BACKGROUND: Adequacy assessment for fine-needle aspiration procedures is a standard of care in large medical centers. Although the benefits of this approach include higher adequacy rates with fewer passes, it costs cytopathologist time and affects other clinical responsibilities. The objective of the current study was to evaluate the use of mobile video streaming (FaceTime) technology with the help of smartphone adapters attached to microscopes for remote adequacy assessment of cytologic samples. METHODS: The study consisted of 2 phases: Phase 1 was a retrospective assessment of 25 samples by a primary pathologist with simultaneous streaming to a second pathologist using a smartphone (iPhone/iPad) FaceTime connection. Data on the adequacy of each sample and preliminary diagnoses were recorded. In phase 2, live cases were assessed prospectively by an onsite primary pathologist and by a remote pathologist using an iPhone/iPad-FaceTime connection. The testing phase involved prospective assessment of additional samples with a resident or cytotechnologist as the slide driver. RESULTS: In phase 1, retrospective evaluation of 25 samples yielded considerable agreement (22 of 25 samples; 88%) between onsite and remote adequacy assessments. Three samples (12%) yielded results that did not agree, including 2 samples that were read as adequate in the onsite evaluation that were assessed as indeterminate using FaceTime. In phase 2 and in the testing phase, 14 samples exhibited considerable agreement on both adequacy and preliminary diagnosis (6 samples in phase 2 and 8 samples in the testing phase) and are currently available for reporting. Problems encountered include software version standardization, camera alignment, and (rarely) comprehension of the audio stream. CONCLUSIONS: The current data indicate that iPhone/iPad FaceTime technology can be used to perform remote adequacy assessments of fine-needle aspirations and can help save valuable time for pathologists.

Suppression of tumor growth in mice by rationally designed pseudopeptide inhibitors of fibroblast activation protein and prolyl oligopeptidase.

Tumor microenvironments (TMEs) are composed of cancer cells, fibroblasts, extracellular matrix, microvessels, and endothelial cells. Two prolyl endopeptidases, fibroblast activation protein (FAP) and prolyl oligopeptidase (POP), are commonly overexpressed by epithelial-derived malignancies, with the specificity of FAP expression by cancer stromal fibroblasts suggesting FAP as a possible therapeutic target. Despite overexpression in most cancers and having a role in angiogenesis, inhibition of POP activity has received little attention as an approach to quench tumor growth. We developed two specific and highly effective pseudopeptide inhibitors, M83, which inhibits FAP and POP proteinase activities, and J94, which inhibits only POP. Both suppressed human colon cancer xenograft growth >90% in mice. By immunohistochemical stains, M83- and J94-treated tumors had fewer microvessels, and apoptotic areas were apparent in both. In response to M83, but not J94, disordered collagen accumulations were observed. Neither M83- nor J94-treated mice manifested changes in behavior, weight, or gastrointestinal function. Tumor growth suppression was more extensive than noted with recently reported efforts by others to inhibit FAP proteinase function or reduce FAP expression. Diminished angiogenesis and the accompanying profound reduction in tumor growth suggest that inhibition of either FAP or POP may offer new therapeutic approaches that directly target TMEs.