Translational and oncologic significance of tertiary lymphoid structures in pancreatic adenocarcinoma

Pancreatic adenocarcinoma (PDAC) is an aggressive tumor with poor survival and limited treatment options. PDAC resistance to immunotherapeutic strategies is multifactorial, but partially owed to an immunosuppressive tumor immune microenvironment (TiME). However, the PDAC TiME is heterogeneous and harbors favorable tumor-infiltrating lymphocyte (TIL) populations. Tertiary lymphoid structures (TLS) are organized aggregates of immune cells that develop within non-lymphoid tissue under chronic inflammation in multiple contexts, including cancers. Our current understanding of their role within the PDAC TiME remains limited; TLS are complex structures with multiple anatomic features such as location, density, and maturity that may impact clinical outcomes such as survival and therapy response in PDAC. Similarly, our understanding of methods to manipulate TLS is an actively developing field of research. TLS may function as anti-tumoral immune niches that can be leveraged as a therapeutic strategy to potentiate both existing chemotherapeutic regimens and potentiate future immune-based therapeutic strategies to improve patient outcomes. This review seeks to cover anatomy, relevant features, immune effects, translational significance, and future directions of understanding TLS within the context of PDAC.

Pre-treatment inflamed tumor immune microenvironment is associated with FOLFIRINOX response in pancreatic cancer

Introduction

Pancreatic adenocarcinoma (PDAC) is an aggressive tumor with limited response to both chemotherapy and immunotherapy. Pre-treatment tumor features within the tumor immune microenvironment (TiME) may influence treatment response. We hypothesized that the pre-treatment TiME composition differs between metastatic and primary lesions and would be associated with response to modified FOLFIRINOX (mFFX) or gemcitabine-based (Gem-based) therapy.

Methods

Using RNAseq data from a cohort of treatment-naïve, advanced PDAC patients in the COMPASS trial, differential gene expression analysis of key immunomodulatory genes in were analyzed based on multiple parameters including tumor site, response to mFFX, and response to Gem-based treatment. The relative proportions of immune cell infiltration were defined using CIBERSORTx and Dirichlet regression.

Results

145 samples were included in the analysis; 83 received mFFX, 62 received Gem-based therapy. Metastatic liver samples had both increased macrophage (1.2 times more, p < 0.05) and increased eosinophil infiltration (1.4 times more, p < 0.05) compared to primary lesion samples. Further analysis of the specific macrophage phenotypes revealed an increased M2 macrophage fraction in the liver samples. The pre-treatment CD8 T-cell, dendritic cell, and neutrophil infiltration of metastatic samples were associated with therapy response to mFFX (p < 0.05), while mast cell infiltration was associated with response to Gem-based therapy (p < 0.05). Multiple immunoinhibitory genes such as ADORA2A, CSF1R, KDR/VEGFR2, LAG3, PDCD1LG2, and TGFB1 and immunostimulatory genes including C10orf54, CXCL12, and TNFSF14/LIGHT were significantly associated with worse survival in patients who received mFFX (p = 0.01). There were no immunomodulatory genes associated with survival in the Gem-based cohort.

Discussion

Our evidence implies that essential differences in the PDAC TiME exist between primary and metastatic tumors and an inflamed pretreatment TiME is associated with mFFX response. Defining components of the PDAC TiME that influence therapy response will provide opportunities for targeted therapeutic strategies that may need to be accounted for in designing personalized therapy to improve outcomes.

Pretreatment Health-Related Quality-of-Life Status and Survival in Pancreatobiliary Surgical Patients

BACKGROUND

Pancreatobiliary (PB) disorders, especially cancer, negatively affect patients' health-related quality of life (HRQoL). However, the influence of baseline, preintervention HRQoL on perioperative and oncologic outcomes has not been well defined. We hypothesized that low baseline HRQoL is associated with worse perioperative and long-term survival outcomes for PB surgical patients.

STUDY DESIGN

Pretreatment Functional Assessment of Cancer Therapy - Hepatobiliary Survey results and clinical data from PB patients (2008 to 2016) from a single center's prospective database were analyzed. Survey responses were aggregated into composite scores and divided into quintiles. Patients in the highest quintile of HRQoL were compared to patients in the bottom four quintiles combined. Overall survival (OS) and disease-free survival (DFS) were analyzed using the Kaplan-Meier method. Logistic and Cox regressions were used to determine associations between quintiles of HRQoL scores and 30-day complications and long-term survival, respectively.

RESULTS

Of 162 patients evaluated, 99 had malignancy, and 63 had benign disease. Median follow-up was 31 months. Baseline HRQoL scores were similar for benign and malignant disease (p = 0.42) and were not associated with the development of any (p = 0.08) or major complications (p = 0.64). Patients with highest quintile HRQoL scores had improved 3-year OS (84.6 vs 61.7%, p = 0.03) compared to patients in the lowest four quintiles of HRQoL. Among cancer patients only, those with the highest quintile scores had improved 3-year OS (81.6 vs 47.4%, p = 0.02). On multivariable analysis, highest quintile HRQoL scores were associated with longer OS and DFS for patients with malignancy.

CONCLUSIONS

Pretreatment HRQoL was associated with both OS and DFS among PB patients and might have prognostic utility. Future studies are necessary to determine whether patients with poorer HRQoL may benefit from targeted psychosocial interventions.

Sociodemographic and Facility-Related Disparities in the Delivery of Guideline-Concordant Therapy Among Patients With Esophageal Adenocarcinoma

PURPOSE:

Evidence on health disparities among patients treated with multimodality therapy protocols is still limited. We aimed to evaluate the associations between patient-level and system-level factors and the receipt of guideline-concordant therapy among patients with esophageal adenocarcinoma (EA).

METHODS:

This is a national cohort study of patients with stage I-III EA in the National Cancer Database (2006-2018) treated with either upfront resection or neoadjuvant therapy followed by surgery. Clinical and pathologic staging data were used for defining guideline-concordant therapy. Logistic regression models were built to identify independent associations between deviations from treatment guidelines and clinical, sociodemographic, and hospital-related factors.

RESULTS:

Among 18,803 patients with EA treated at 1,049 hospitals, 4,511 had an endoscopic resection, 4,866 had upfront resection, and 9,426 had neoadjuvant therapy followed by surgery. A total of 16,002 patients (85.1%) received guideline-concordant therapy. Patients who were age 70 years or older (odds ratio [OR] 1.35; 95% CI, 1.14 to 1.60), had a Charlson-Deyo modified score of ≥ 1, and were treated at hospitals with a safety-net burden of ≥ 10% (OR 1.13; 95% CI, 1.02 to 1.25) had higher risk of deviations from guidelines, whereas treatment at high-volume facilities (OR 0.84; 95% CI, 0.74 to 0.95) and diagnosis after 2011 decreased this risk. Relative to cT0-1N0 patients, those with cT2N0 disease had the highest risk of deviations from guideline-concordant therapy (OR 3.76; 95% CI, 3.30 to 4.29). Among patients treated at high-volume facilities, safety-net burden over 10% increased the risk of deviations (OR 1.26; 95% CI, 1.01 to 1.57).

CONCLUSION:

The delivery of guideline-concordant therapy among patients with EA varies significantly across clinical stage groups and is associated with several sociodemographic disparities. This knowledge should be a resource for future quality improvement strategies intended to address inequitable care within vulnerable populations.

Factors associated with inability to return to intended oncologic treatment in pancreatic cancer

BACKGROUND

Return to Intended Oncologic Treatment (RIOT) has been proposed as a quality metric in the care of cancer patients. We sought to define factors associated with inability to RIOT in Pancreatic Ductal Adenocarcinoma (PDAC) patients.

METHODS

The NCDB was queried for patients who underwent pancreaticoduodenectomy for pathologic stage IB, IIA, or IIB PDAC from 2010 to 2016. Multivariable binary logistic regression models identified factors associated with failure to RIOT, and Kaplan-Meier survival analysis and Cox multivariable regression models demonstrated the impact of failure to RIOT on survival.

RESULTS

Increasing age (p < .001), Hispanic race (p = .002), pathological stage IB (p = .004) and IIA (p = .001) as compared to IIB, increasing hospital stay (p < .001), and open surgical approach (p = .024) were associated with increased risk of inability to RIOT. Male sex (p < .001), Charlson-Deyo scores of 0 (p < .001) and 1 (p = .001) as compared to >2, negative surgical margins (p = .048), receiving care at academic institutions (p = .001), and increasing institutional case volume (p = .001) were associated with improved odds of RIOT.

CONCLUSIONS

Patient features can impact RIOT and should be considered when designing multi-modality treatment strategies.

High-Fat Diet Drives an Aggressive Pancreatic Cancer Phenotype

BACKGROUND

Emerging evidence indicates associations between high-fat diet (HFD), metabolic syndrome (MetS), and increased risk of pancreatic cancer. However, individual components of an HFD that increase cancer risk have not been isolated. In addition, a specific pattern of cytokine elevation by which MetS drives pancreatic tumor progression is not well described. We hypothesized that oleic acid (OA), a major component of HFD, would augment pancreatic neoplastic processes.

METHODS

An orthotopic pancreatic cancer model with Panc02 cells was used to compare the effect of low-fat diet to OA-based HFD on cancer progression. Tumors were quantitated, analyzed by immunohistochemistry. In addition, serum cytokine levels were quantitated. Proliferation, migration assays, and expression of epithelial-to-mesenchymal transition factors were evaluated on Panc02 and MiaPaCa-2 pancreatic cancer cells cultured in high concentrations of OA.

RESULTS

HFD tumor-bearing mice (n = 8) had an 18% weight increase (P < 0.001) and increased tumor burden (P < 0.05) compared with the low-fat diet tumor-bearing group (n = 6). HFD tumors had significantly increased angiogenesis (P < 0.001) and decreased apoptosis (P < 0.05). Serum of HFD mice demonstrated increased levels of glucagon and glucagon-like peptide-1. Two pancreatic cancer cell lines cultured in OA demonstrated significant increases in proliferation (P < 0.001) and a >2.5-fold increase in cell migration (P < 0.001) when treated with OA. Panc02 treated with OA had increased expression of epithelial-to-mesenchymal transition factors SNAI-1 (Snail) and Zeb-1(P < 0.01).

CONCLUSIONS

High-fat conditions in vitro and in vivo resulted in an aggressive pancreatic cancer phenotype. Our data support further investigations elucidating molecular pathways augmented by MetS conditions to identify novel therapeutic strategies for pancreatic cancer.

Preinvasive Colorectal Lesions of African Americans Display an Immunosuppressive Signature Compared to Caucasian Americans

Background

African Americans (AAs) have higher colorectal cancer (CRC) incidence and mortality rate than Caucasian Americans (CAs). Recent studies suggest that immune responses within CRCs contribute to the disparities. If racially distinct immune signatures are present in the early phases of carcinogenesis, they could be used to develop interventions to prevent or slow disease.

Methods

We selected a convenience sample of 95 patients (48 CAs, 47 AAs) with preinvasive colorectal adenomas from the surgical pathology laboratory at the Medical University of South Carolina. Using immunofluorescent-conjugated antibodies on tissue slides from the lesions, we quantified specific immune cell populations: mast cells (CD117⁺), Th17 cells (CD4⁺RORC⁺), and NK cell ligand (MICA/B) and inflammatory cytokines, including IL-6, IL-17A, and IFN-γ. We compared the mean density counts (MDCs) and density rate ratios (RR) and 95% CI of immune markers between AAs to CAs using negative binomial regression analysis. We adjusted our models for age, sex, clinicopathologic characteristics (histology, location, dysplasia), and batch.

Results

We observed no racial differences in age or sex at the baseline endoscopic exam. AAs compared to CAs had a higher prevalence of proximal adenomas (66% vs. 40%) and a lower prevalence of rectal adenomas (11% vs. 23%) (p =0.04) but no other differences in pathologic characteristics. In age, sex, and batch adjusted models, AAs vs. CAs had lower RRs for cells labeled with IFNγ (RR 0.50 (95% CI 0.32-0.81); p=0.004) and NK cell ligand (RR 0.67 (0.43-1.04); p=0.07). In models adjusted for age, sex, and clinicopathologic variables, AAs had reduced RRs relative to CAs for CD4 (p=0.02), NK cell ligands (p=0.01), Th17 (p=0.005), mast cells (p=0.04) and IFN-γ (p< 0.0001).

Conclusions

Overall, the lower RRs in AAs vs. CAs suggests reduced effector response capacity and an immunosuppressive (‘cold’) tumor environment. Our results also highlight the importance of colonic location of adenoma in influencing these differences; the reduced immune responses in AAs relative to CAs may indicate impaired immune surveillance in early carcinogenesis. Future studies are needed to understand the role of risk factors (such as obesity) in influencing differences in immune responses by race.

Differential immune signatures in the tumor microenvironment are associated with colon cancer racial disparities

Background

Disparities in colon cancer (CC) outcomes may be due to a more aggressive phenotype in African American patients in the setting of a decreased tumor immunity, though the precise mechanism for this result has not been well elucidated. To explore the molecular factors underlying CC disparities, we compared the immunogenomic signatures of CC from African American and European American patients.

Methods

We identified all CC patients from the publicly available Cancer Genome Atlas for whom race and survival data are available. Immunophenotype signatures were established for African American and European American patients. Comparisons were made regarding survival and a multivariable linear regression model was created to determine the association of immune cellular components with race. Differential gene expression was also assessed.

Results

Of the 254 patients identified, 58 (23%) were African American and 196 (77%) were European American. African American patients had a decreased progression free survival (p = 0.04). Tumors from African American patients displayed a reduced fraction of macrophages and CD8⁺ T cells and an increased fraction of B cells compared with tumors from European Americans. Differences persisted when controlling for sex, age, and disease stage. Immunostimulatory and immunoinhibitory gene profiles including major histocompatibility complex expression differed by race.

Conclusions

Differences in the tumor immune microenvironment of African American as compared to European American CC specimens may play a role in the survival differences between the groups. These differences may provide targeted therapeutic opportunities.

Synchronous Upper Intestinal Neurofibromas and Duodenal Periampullary Well-Differentiated Neuroendocrine Tumor Associated With Neurofibromatosis 1

Neurofibromatosis type I (NF1) is an autosomal dominant genetic disorder associated with characteristic skin findings, as well as a fourfold increase in risk of malignancy. NF1 patient malignancies commonly include the central and peripheral nervous system, but these patients are also at high risk of developing gastrointestinal (GI) tumors. While most often these GI tumors are benign upper GI neurofibromas; clinicians should have a high suspicion for malignant tumors, degeneration into a malignant peripheral nerve sheath tumor or less common associated malignancies such as well-differentiated neuroendocrine tumor (formerly carcinoid tumor), when patients present with multiple GI tumors. Our patient underwent a Whipple for symptomatic neurofibromas associated with NF1 and was unexpectedly discovered to have a metastatic duodenal well-differentiated neuroendocrine tumor. The patient is a 66-year-old man with NF1 who presented with hematemesis and was found to have large gastric neurofibromas and an ampullary neurofibroma based on endoscopy and radiological imaging. Another ostensive neurofibroma was noted distally. A pancreatoduodenectomy was performed. Pathological examination identified the neurofibromas but the tumor measuring 1.4cm and arising from the minor duodenal papilla was, in fact, a synchronous well-differentiated neuroendocrine tumor metastatic to regional lymph nodes, consistent with pT2 pN1, Stage IIIB cancer. NF1 patients with multiple GI tumors are at an increased risk for malignancy. Therefore, a high index of suspicion for malignancy in any patient with NF1 presenting with gastrointestinal symptoms has implications for a surgeon, warranting not only a further diagnostic investigation, but also an appropriate surgical intervention and sampling for nodal spread. Because of the possibility of a simultaneous cancer, it is crucial to assess all suspicious tumors even if the masses appear endoscopically benign.

What is Elective Oncologic Surgery in the Time of COVID-19? A Literature Review of the Impact of Surgical Delays on Outcomes in Patients with Cancer

Background

The impact of the COVID-19 pandemic has spread beyond those infected with SARS-CoV-2. Its widespread consequences have affected cancer patients whose surgeries may be delayed in order to minimize exposure and conserve resources.

Methods

Experts in each surgical oncology subspecialty were selected to perform a review of the relevant literature. Articles were obtained through PubMed searches in each cancer subtype using the following terms: delay to surgery, time to surgery, outcomes, and survival.

Results

Delays in surgery > 4 weeks in breast cancer, ductal carcinoma in situ, T1 pancreatic cancer, ovarian cancer, and pediatric osteosarcoma, negatively impacted survival. Studies on hepatocellular cancer, colon cancer, and melanoma (Stage I) demonstrated reduced survival with delays > 3 months.

Conclusion

Studies have shown that short-term surgical delays can result in negative impacts on patient outcomes in multiple cancer types as well as in situ carcinoma. Conversely, other cancers such as gastric cancer, advanced melanoma and pancreatic cancer, well-differentiated thyroid cancer, and several genitourinary cancers demonstrated no significant outcome differences with surgical delays.

SLC36A1-mTORC1 signaling drives acquired resistance to CDK4/6 inhibitors

The cyclin-dependent kinase 4/6 (CDK4/6) kinase is dysregulated in melanoma, highlighting it as a potential therapeutic target. CDK4/6 inhibitors are being evaluated in trials for melanoma and additional cancers. While beneficial, resistance to therapy is a concern, and the molecular mechanisms of such resistance remain undefined. We demonstrate that reactivation of mammalian target of rapamycin 1 (mTORC1) signaling through increased expression of the amino acid transporter, solute carrier family 36 member 1 (SLC36A1), drives resistance to CDK4/6 inhibitors. Increased expression of SLC36A1 reflects two distinct mechanisms: (i) Rb loss, which drives SLC36A1 via reduced suppression of E2f; (ii) fragile X mental retardation syndrome-associated protein 1 overexpression, which promotes SLC36A1 translation and subsequently mTORC1. Last, we demonstrate that a combination of a CDK4/6 inhibitor with an mTORC1 inhibitor has increased therapeutic efficacy in vivo, providing an important avenue for improved therapeutic intervention in aggressive melanoma.

Genomics meets immunity in pancreatic cancer: Current research and future directions for pancreatic adenocarcinoma immunotherapy

Pancreatic adenocarcinoma (PDAC) remains a formidable disease that needs improved therapeutic strategies. Even though immunotherapy has revolutionized treatment for various solid tumor types, it remains largely ineffective in treating individuals with PDAC. This review describes how the application of genome-wide analysis is revitalizing the field of PDAC immunotherapy. Major themes include new insights into the body’s immune response to the cancer, and key immunosuppressive elements that blunt that antitumor immunity. In particular, new evidence indicates that T cell-based antitumor immunity against PDAC is more common, and more easily generated, than previously thought. However, equally common are an array of cellular and molecular defenses employed by the tumor against those T cells. These discoveries have changed how current immunotherapies are deployed and have directed development of novel strategies to better treat this disease. Thus, the impact of genomic analysis has been two-fold: both in demonstrating the heterogeneity of immune targets and defenses in this disease, as well as providing a powerful tool for designing and identifying personalized therapies that exploit each tumor’s unique phenotype. Such personalized treatment combinations may be the key to developing successful immunotherapies for pancreatic adenocarcinoma.

miR-145 Antagonizes SNAI1-Mediated Stemness and Radiation Resistance in Colorectal Cancer

Epithelial-to-mesenchymal transition (EMT) has been closely linked with therapy resistance and cancer stem cells (CSCs). However, EMT pathways have proven challenging to therapeutically target. MicroRNA 145 (miR-145) targets multiple stem cell transcription factors and its expression is inversely correlated with EMT. Therefore, we hypothesized that miR-145 represents a therapeutic target to reverse snail family transcriptional repressor 1 (SNAI1)-mediated stemness and radiation resistance (RT). Stable expression of SNAI1 in DLD1 and HCT116 cells (DLD1-SNAI1; HCT116-SNAI1) increased expression of Nanog and decreased miR-145 expression compared to control cells. Using a miR-145 luciferase reporter assay, we determined that ectopic SNAI1 expression significantly repressed the miR-145 promoter. DLD1-SNAI1 and HCT116-SNAI1 cells demonstrated decreased RT sensitivity and, conversely, miR-145 replacement significantly enhanced RT sensitivity. Of the five parental colon cancer cell lines, SW620 cells demonstrated relatively high endogenous SNAI1 and low miR-145 levels. In the SW620 cells, miR-145 replacement decreased CSC-related transcription factor expression, spheroid formation, and radiation resistance. In rectal cancer patient-derived xenografts, CSC identified by EpCAM+/aldehyde dehydrogenase (ALDH)+ demonstrated high expression of SNAI1, c-Myc, and Nanog compared with non-CSCs (EpCAM+/ALDH-). Conversely, patient-derived CSCs demonstrated low miR-145 expression levels relative to non-CSCs. These results suggest that the SNAI1:miR-145 pathway represents a novel therapeutic target in colorectal cancer to overcome RT resistance.

The clinical implications of immunogenomics in colorectal cancer: A path for precision medicine

Colorectal cancer (CRC) remains the third most common malignancy and the second-leading cause of cancer-related deaths in the United States. Large multi-omic databases, such as The Cancer Genome Atlas and the International Colorectal Cancer Subtyping Consortium, have identified distinct molecular subtypes related to anatomy. The identification of genomic alterations in CRC is now critical because of the recent success and US Food and Drug Administration approval of pembrolizumab and nivolumab for microsatellite-instable tumors. In parallel, landmark studies have established the prognostic significance of the CRC tumor-infiltrating lymphocyte and the clinical impact of the tumor immune microenvironment. As a result, there is a growing appreciation for immunogenomics, the interconnected relation between tumor genomics and the immune microenvironment. The clinical implications of CRC immunogenomics continue to expand, and it will likely serve as a guide for next-generation immunotherapy strategies for improving outcomes for this disease. Cancer 2018;124:1650-9. © 2018 American Cancer Society.

Sunitinib represses regulatory T cells to overcome immunotolerance in a murine model of hepatocellular cancer

Successful development of immunotherapeutic strategies for hepatocellular cancer (HCC) has been impeded by limited understanding of tumor-induced profound tolerance and lack of a clinically faithful HCC model. Recently, we developed a novel model that recapitulates typical features of human HCC. Using this clinically relevant model, we demonstrate that tumor growth impairs host immunity and causes a profound exhaustion of tumor antigen-specific (TAS) CD8⁺ T cells. Increase in frequency and suppressive function of regulatory T cells (Tregs) is critically involved in this tumor-induced immune dysfunction. We further demonstrate that sunitinib suppresses Tregs and prevents tumor-induced immune tolerance, allowing TAS immunization to activate endogenous CD8⁺ T cells. As a result, this combinational strategy delays tumor growth. Importantly, the additional integration of exogenous naïve TAS CD8⁺ T cells by adoptive cell transfer (ACT) leads to the elimination of the established tumors without recurrence and promotes long-term survival of the treated mice. Mechanistically, sunitinib treatment primes the antitumor immune response by significantly decreasing Treg frequency, reducing TGF-β and IL-10 production by Tregs, and also protecting TAS CD8⁺ T cells from tumor-induced deletion in the setting of HCC. Taken together, sunitinib quantitatively and qualitatively modifies Tregs to overcome tumor-induced immune deficiency, suggesting the potential of sunitinib as a therapeutic immune activator for HCC control.

Therapeutic implications of bioactive sphingolipids: A focus on colorectal cancer

Therapy of colorectal cancer (CRC), especially a subset known as locally advanced rectal cancer, is challenged by progression and recurrence. Sphingolipids, a lipid subtype with vital roles in cellular function, play an important role in CRC and impact on therapeutic outcomes. In this review we discuss how dietary sphingolipids or the gut microbiome via alterations in sphingolipids influence CRC carcinogenesis. In addition, we discuss the expression of sphingolipid enzymes in the gastro-intestinal tract, their alterations in CRC, and the implications for therapy responsiveness. Lastly, we highlight some novel therapeutics that target sphingolipid signaling and have potential applications in the treatment of CRC. Understanding how sphingolipid metabolism impacts cell death susceptibility and drug resistance will be critical toward improving therapeutic outcomes.

The impact of metabolic syndrome on outcome and response to neoadjuvant chemoradiation in locally advanced rectal cancer patients

BACKGROUND AND OBJECTIVES

Metabolic syndrome (MetS) is a constellation of cardiovascular risk factors shown to increase the risk of developing various malignancies, as well as diminish tumor response to conventional therapies. The effects of MetS and its individual components on therapeutic response and treatment-related outcomes were examined in patients with locally advanced rectal cancer (LARC).

METHODS

Data was retrospectively collected on LARC patients treated with neoadjuvant chemoradiation (nCRT) and surgery. Medical records were reviewed for patient characteristics, staging, treatment plan, and outcomes.

RESULTS

One hundred two patients were included in the study. Patients with HTN had a significantly decreased nCRT response and were four times more likely to experience a poor response to treatment compared to patients without HTN. Additionally, HTN was found to significantly increase the rate of surgical complications. Neither DM nor obesity exhibited any significant effect on therapeutic response or complication rates, either individually or in combination with another risk factor.

CONCLUSION

This study demonstrates the importance of considering underlying MetS risk factors, especially HTN, when predicting tumor response in LARC patients undergoing nCRT followed by radical surgery. The results provide support for an increased focus on pre-treatment risk factor control to optimize cancer therapy outcomes.

CCR 20th Anniversary Commentary: RAS as a Biomarker for EGFR--Targeted Therapy for Colorectal Cancer-From Concept to Practice

Clinical data support the use of EGFR mAbs in patients with metastatic colorectal cancer (mCRC) with wild-type RAS status. This notion, hypothesized in the review article by Camp, Ellis, and colleagues in the January 1, 2005, issue of Clinical Cancer Research, serves as an example of the successful application of basic science principles to clinical practice. The exclusion of patients with mCRC with Ras-mutated tumors from therapy with EGFR mAbs has led to improved outcomes while sparing patients unnecessary and potentially harmful therapy. See related article by Camp et al., Clin Cancer Res 2005;11(1): January 1, 2005;397-405.

Evaluation and management of intrahepatic and extrahepatic cholangiocarcinoma

Cholangiocarcinomas are rare biliary tract tumors that are often challenging to diagnose and treat. Cholangiocarcinomas are generally categorized as intrahepatic or extrahepatic depending on their anatomic location. The majority of patients with cholangiocarcinoma do not have any of the known or suspected risk factors and present with advanced disease. The optimal evaluation and management of patients with cholangiocarcinoma requires thoughtful integration of clinical information, imaging studies, cytology and/or histology, as well as prompt multidisciplinary evaluation. The current review focuses on recent advances in the diagnosis and treatment of patients with cholangiocarcinoma and, in particular, on the role of endoscopy, surgery, transplantation, radiotherapy, systemic therapy, and liver-directed therapies in the curative or palliative treatment of these individuals. Cancer 2016;122:1349-1369. © 2016 American Cancer Society.

MicroRNA-510 promotes cell and tumor growth by targeting peroxiredoxin1 in breast cancer

Introduction

MicroRNAs are small non-coding RNAs that are involved in the post-transcriptional negative regulation of mRNAs. MicroRNA 510 (miR-510) was initially shown to have a potential oncogenic role in breast cancer by the observation of its elevated levels in human breast tumor samples when compared to matched non-tumor samples. Few targets have been identified for miR-510. However, as microRNAs function through the negative regulation of their direct targets, the identification of those targets is critical for the understanding of their functional role in breast cancer.

Methods

Breast cancer cell lines were transfected with pre-miR-510 or antisense miR-510 and western blotting and quantitative real time PCR were performed. Functional assays performed included cell growth, migration, invasion, colony formation, cytotoxicity and in vivo tumor growth. We performed a PCR assay to identify novel direct targets of miR-510. The study focused on peroxiredoxin 1 (PRDX1) as it was identified through our screen and was bioinformatically predicted to contain a miR-510 seed site in its 3' untranslated region (3'UTR). Luciferase reporter assays and site-directed mutagenesis were performed to confirm PRDX1 as a direct target. The Student's two-sided, paired t-test was used and a P-value less than 0.05 was considered significant.

Results

We show that miR-510 overexpression in non-transformed and breast cancer cells can increase their cell growth, migration, invasion and colony formation in vitro. We also observed increased tumor growth when miR-510 was overexpressed in vivo. We identified PRDX1 through a novel PCR screen and confirmed it as a direct target using luciferase reporter assays. The reintroduction of PRDX1 into breast cancer cell lines without its regulatory 3'UTR confirmed that miR-510 was mediating its migratory phenotype at least in part through the negative regulation of PRDX1. Furthermore, the PI3K/Akt pathway was identified as a positive regulator of miR-510 both in vitro and in vivo.

Conclusions

In this study, we provide evidence to support a role for miR-510 as a novel oncomir. We show that miR-510 directly binds to the 3'UTR of PRDX1 and blocks its protein expression, thereby suppressing migration of human breast cancer cells. Taken together, these data support a pivotal role for miR-510 in breast cancer progression and suggest it as a potential therapeutic target in breast cancer patients.

SNAI2 modulates colorectal cancer 5-fluorouracil sensitivity through miR145 repression

Epithelial-to-mesenchymal transition (EMT) has been associated with poor treatment outcomes in various malignancies and is inversely associated with miRNA145 expression. Therefore, we hypothesized that SNAI2 (Slug) may mediate 5-fluorouracil (5FU) chemotherapy resistance through inhibition of miR145 in colorectal cancer and thus represents a novel therapeutic target to enhance current colorectal cancer treatment strategies. Compared with parental DLD1 colon cancer cells, 5FU-resistant (5FUr) DLD1 cells demonstrated features of EMT, including >2-fold enhanced invasion (P < 0.001) and migration, suppressed E-cadherin expression, and 2-fold increased SNAI2 expression. DLD1 and HCT116 cells with stable expression of SNAI2 (DLD1/SNAI2; HCT116/SNAI2) also demonstrated EMT features such as the decreased E-cadherin as well as significantly decreased miR145 expression, as compared with control empty vector cells. On the basis of an miR145 luciferase promoter assay, we demonstrated that SNAI2 repressed activity of the miR145 promoter in the DLD1 and HCT116 cells. In addition, the ectopic expressing SNAI2 cell lines demonstrated decreased 5FU sensitivity, and, conversely, miR145 replacement significantly enhanced 5FU sensitivity. In the parental SW620 colon cancer cell line with high SNAI2 and low miR145 levels, inhibition of SNAI2 directly with short hairpin sequence for SNAI2 and miR145 replacement therapy both decreased vimentin expression and increased in vitro 5FU sensitivity. In pretreatment rectal cancer patient biopsy samples, low miR145 expression levels correlated with poor response to neoadjuvant 5FU-based chemoradiation. These results suggested that the SNAI2:miR145 pathway may represent a novel clinical therapeutic target in colorectal cancer and may serve as a response predictor to chemoradiation therapy.

Phase 2 trial of induction gemcitabine, oxaliplatin, and cetuximab followed by selective capecitabine-based chemoradiation in patients with borderline resectable or unresectable locally advanced pancreatic cancer

PURPOSE

To evaluate, in a phase 2 study, the safety and efficacy of induction gemcitabine, oxaliplatin, and cetuximab followed by selective capecitabine-based chemoradiation in patients with borderline resectable or unresectable locally advanced pancreatic cancer (BRPC or LAPC, respectively).

METHODS AND MATERIALS

Patients received gemcitabine and oxaliplatin chemotherapy repeated every 14 days for 6 cycles, combined with weekly cetuximab. Patients were then restaged; "downstaged" patients with resectable disease underwent attempted resection. Remaining patients were treated with chemoradiation consisting of intensity modulated radiation therapy (54 Gy) and concurrent capecitabine; patients with borderline resectable disease or better at restaging underwent attempted resection.

RESULTS

A total of 39 patients were enrolled, of whom 37 were evaluable. Protocol treatment was generally well tolerated. Median follow-up for all patients was 11.9 months. Overall, 29.7% of patients underwent R0 surgical resection (69.2% of patients with BRPC; 8.3% of patients with LAPC). Overall 6-month progression-free survival (PFS) was 62%, and median PFS was 10.4 months. Median overall survival (OS) was 11.8 months. In patients with LAPC, median OS was 9.3 months; in patients with BRPC, median OS was 24.1 months. In the group of patients who underwent R0 resection (all of which were R0 resections), median survival had not yet been reached at the time of analysis.

CONCLUSIONS

This regimen was well tolerated in patients with BRPC or LAPC, and almost one-third of patients underwent R0 resection. Although OS for the entire cohort was comparable to that in historical controls, PFS and OS in patients with BRPC and/or who underwent R0 resection was markedly improved.

The Diagnostic Significance of a Mucocele of the Appendix

Appendiceal mucoceles are rare lesions with a variable clinical presentation often identified incidentally on imaging or at laparotomy/laparoscopy for an unrelated diagnosis. Mucocele of the appendix may be a benign or malignant process, making early recognition based on symptoms and key radiographic characteristics of the utmost importance for optimal patient management. Here we present the case of a patient presenting with non-specific abdominal complaints suffering from appendiceal mucocele perforation due to low-grade mucinous adenocarcinoma.

Slug expression inhibits calcitriol-mediated sensitivity to radiation in colorectal cancer

Recently, a reciprocal relationship between calcitriol and epithelial-to-mesenchymal transition has been described. Therefore, we hypothesized that calcitriol (1α,25-dihydroxyvitamin D₃) would enhance radiation sensitivity in colorectal cancer regulated by epithelial mesenchymal transition. Vitamin-D receptor, E-cadherin and vimentin protein as well as E-cadherin, Snail and Slug mRNA levels were assessed in a panel of human colorectal cancer cell lines at baseline and in response calcitriol. We defined cell lines as calcitriol sensitive based on demonstrating an enhanced epithelial phenotype with increased E-cadherin, reduced vimentin and decreased expression of Snail and Slug as well as decreased cellular migration in response to calcitriol. In calcitriol sensitive cells, including DLD-1 and HCT116, 24 h calcitriol pre-treatment enhanced the radiation sensitivity by 2.3- and 2.6-fold, respectively, at 4 Gy (P < 0.05). In contrast, SW620 cells with high baseline mesenchymal features including high Slug and vimentin expression with low E-cadherin expression demonstrated no significant radiation sensitizing response to calcitriol treatment. Similarly, transfection of Slug in the calcitriol sensitive colon cancer cell lines, DLD-1 and HCT 116, completely inhibited the radiation sensitizing effect of calcitriol. Collectively, we demonstrate that calcitriol can enhance the therapeutic effects of radiation in colon cancer cells and Slug expression mitigates this observed effect potentially representing an effective biomarker for calcitriol therapy.

Abstract 3012: The CaSm oncogene promotes proliferation, invasion, and chemoresistance of pancreatic cancer cells

Introduction: The Cancer associated Sm-like (CaSm) oncogene is overexpressed in 87% of human pancreatic tumor samples and its expression is necessary for in vivo tumor formation. Evidence supports that CaSm modulates mRNA degradation; however, CaSm's target genes and the mechanisms by which CaSm promotes pancreatic cancer remain largely unknown. We hypothesize that CaSm overexpression promotes neoplastic development by altering several hallmarks of cancer - including proliferation, metastasis, and chemoresistance.

Methods and Results: Human CaSm was overexpressed in Panc1 cells (tet-on CaSm Panc1) using the Clontech Retro-X doxycycline inducible system with tet-on driver Panc1 cells used as controls in all experiments. Trypan blue cell counts presented a 2-fold increase in cellular proliferation following CaSm overexpression compared with driver and noninduced controls. Using SRB assays to evaluate cytotoxicity, CaSm induction increased resistance to gemcitabine at all drug concentrations (0.1-100uM) and CaSm overexpression also significantly decreased apoptosis (sub-G1 DNA content by cell cycle analysis) after treatment with 200nM gemcitabine. Real-time PCR-based microarray analysis was used to identify altered gene expression upon CaSm induction, showing decreased Bad and E2F1 expression and increased Bcl-xL mRNA levels; results were confirmed using qPCR and western blot analysis. These genes have been implicated in gemcitabine resistance in multiple cancers and provide a possible mechanism behind CaSm-mediated chemoresistance.

To analyze migration and invasion, tet-on CaSm and tet-on driver Panc1 cells were plated onto fibronectin- or matrigel-coated Boyden chambers for 4 and 48 hours respectively. CaSm overexpression significantly increased transwell migration by more than 2-fold and invasion by nearly 4-fold. Microarrays identified increased MMP1 and uPAR mRNA upon CaSm induction, congruent with increased metastasis in vivo. Furthermore, western blot demonstrated that CaSm overexpression decreased E-cadherin and increased N-cadherin, characteristic of epithelial-to-mesenchymal transition (EMT) that is also known to promote both metastasis and chemoresistance in vivo. Investigation of EMT transcription factors by qPCR revealed that CaSm overexpression increases mRNA levels of Slug demonstrating a possible mechanism behind CaSm-induced EMT.

Conclusions: Induced CaSm expression results in increased proliferation, decreased chemotherapeutic sensitivity, and enhanced migration/invasion in pancreatic cancer cells. CaSm upregulation alters the gene expression of critical mediators of apoptosis, metastasis, and EMT, which complements CaSm's proposed role in mRNA regulation and provides a mechanism for CaSm-mediated neoplastic progression.

Citation Format: Elizabeth C. Little, E. Ramsay Camp, Cindy Wang, Patricia M. Watson, Dennis K. Watson, David J. Cole. The CaSm oncogene promotes proliferation, invasion, and chemoresistance of pancreatic cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3012. doi:10.1158/1538-7445.AM2013-3012

Transferrin receptor targeting nanomedicine delivering wild-type p53 gene sensitizes pancreatic cancer to gemcitabine therapy

To overcome gene therapy barriers such as low transfection efficiency and nonspecific delivery, liposomal nanoparticles targeted by a single-chain antibody fragment to the transferrin receptor (TfRscFv) delivering wild-type (wt) human p53 (SGT-53) were developed for tumor-specific targeting. We hypothesize that SGT-53 in combination with gemcitabine will demonstrate enhanced therapeutic benefit in an in vivo metastatic pancreatic cancer model. Intrasplenic injection of 1 × 10(6) Panc02 murine pancreatic cancer cells was used to generate in vivo hepatic metastatic tumors. Nanoparticle localization was assessed by tail vein injection of TfRscFv with fluorescently labeled oligonucleotides (6-carboxyfluorescein phosphoramidite (6FAM) ODN) imaged by Xenogen IVIS 200 scan. SGT-53 (equivalent to 30 μg of p53 intravenously) and gemcitabine (20 mg/kg intraperitoneally) alone and in combination were administered biweekly and compared with untreated mice. Survival was determined by blinded daily assessment of morbidity. Human wtp53 expression and transferrin levels in the tumors were assessed by western blot analysis. Tumor burden was quantified by liver weight. Xenogen imaging demonstrated tumor-specific uptake of TfRscFv-6FAM ODN. Exogenous human wtp53 protein was detected in the SGT-53-treated tumors compared with control. Compared with untreated mice with metastatic tumors demonstrating median survival of 20 days, SGT-53, gemcitabine and the combination demonstrated improved median survival of 29, 30 and 37 days, respectively. The combination treatment prolonged median survival when compared with single drug treatment and decreased tumor burden. The tumor targeting liposomal-based SGT-53 nanoparticle is capable of sensitizing pancreatic cancer to conventional chemotherapy in pancreatic cancer models. This approach has the potential to be translated into a new, more effective therapy for pancreatic cancer. Further optimization is ongoing, moving towards a Phase 1B/2 clinical trial.

Merkel cell carcinoma: identification of prognostic factors unique to tumors located in the head and neck based on analysis of SEER data

OBJECTIVES/HYPOTHESIS

Merkel cell carcinoma (MCC) is an aggressive cutaneous neoplasm that occurs most frequently in the head and neck region. Because of its rarity, prognostic factors are poorly characterized. Head and neck MCC (HN-MCC) may require separate consideration from MCC that occurs in other anatomic regions. Our objective was to determine the relevance of clinicopathologic parameters as prognostic factors in a large series of patients with HN-MCC and to compare these to a series of patients with non-head and neck MCC (NHN-MCC).

STUDY DESIGN

Retrospective analysis of large population database.

METHODS

Patients with MCC were identified using the Surveillance, Epidemiology, and End Results database and categorized according to tumor location either 1) within or 2) outside of the head and neck region. Clinicopathologic data were compared between groups. Retrospective univariable and multivariable analyses of factors associated with disease-specific survival (DSS) were performed.

RESULTS

We identified 2,104 patients with HN-MCC and 2,272 with NHN-MCC. DSS was similar between groups. Independent prognostic factors in HN-MCC are male sex (P < .001), lip primary site (P = .005), tumor extension beyond the dermis (P = .03), histologically confirmed nodal disease (P < .001), absence of histologic lymph node evaluation (P = .01), and distant metastasis (P = .001). Male sex and tumor extension limited to the subcutis are prognostic factors that are unique to HN-MCC.

CONCLUSIONS

Because independent markers of aggressive disease appear to be unique in HN-MCC, it is important that future studies provide separate consideration for HN-MCC to allow for the most accurate identification of prognostic indicators and assessment of treatment outcomes accordingly.

Slug expression enhances tumor formation in a noninvasive rectal cancer model

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) is a series of molecular changes allowing epithelial cancer cells to acquire properties of mesenchymal cells: increased motility, invasion, and protection from apoptosis. Transcriptional regulators such as Slug mediate EMT, working in part to repress E-cadherin transcription. We report a novel, noninvasive in vivo rectal cancer model to explore the role of Slug in colorectal cancer (CRC) tumor development.

METHODS

For the generation of DLD-1 cells overexpressing Slug (Slug DLD-1), a Slug or empty (Empty DLD-1) pCMV-3Tag-1 (kanamycin-resistant) vector was used for transfection. Cells were evaluated for Slug and E-cadherin expression, and cell migration and invasion. For the in vivo study, colon cancer cells (parental DLD-1, Slug DLD-1, empty DLD-1, and HCT-116) were submucosally injected into the posterior rectum of nude mice using endoscopic guidance. After 28 d, tumors were harvested and tissue was analyzed.

RESULTS

Slug expression in our panel of colon cancer cell lines was inversely correlated with E-cadherin expression and enhanced migration/invasion. Slug DLD-1 cells demonstrated a 21-fold increased Slug and 19-fold decreased E-cadherin expression compared with empty DLD-1. Similarly, the Slug DLD-1 cells had significantly enhanced cellular migration and invasion. In the orthotopic rectal cancer model, Slug DLD-1 cells formed rectal tumors in 9/10 (90%) of the mice (mean volume = 458 mm(3)) compared with only 1/10 (10%) with empty DLD-1 cells.

CONCLUSION

Slug mediates EMT with enhanced in vivo rectal tumor formation. Our noninvasive in vivo model enables researchers to explore the molecular consequences of altered genes in a clinically relevant rectal cancer in an effort to develop novel therapeutic approaches for patients with rectal cancer.

Effect of chemotherapeutic stress on induction of vascular endothelial growth factor family members and receptors in human colorectal cancer cells

Vascular endothelial growth factor (VEGF) is induced by stress. We determined whether chemotherapy (genotoxic stress) could induce expression of VEGF and VEGF receptors (VEGFR) in human colorectal cancer cells. The colorectal cancer cell lines HT29, RKO, and HCT116 were acutely exposed to increasing doses of oxaliplatin or 5-fluorouracil for 2, 6, and 24 h in vitro. Expression of VEGF ligand family members, VEGFRs, and signaling intermediates was determined by reverse transcription-PCR and Northern and Western blotting. The effect of oxaliplatin on VEGF-A transcriptional activity was determined by promoter assays. Acute exposure of human colorectal cancer cells to oxaliplatin led to a marked induction of VEGF-A mRNA and protein, whereas 5-fluorouracil alone or when added to oxaliplatin did not cause a further increase in VEGF levels. VEGF-A promoter activity was induced by oxaliplatin exposure. Expression of VEGF-C, placental growth factor, VEGFR-1, and neuropilin-1 levels were also increased when cells were treated with oxaliplatin. Oxaliplatin led to an increase in Akt and Src activation in HT29 cells. In contrast, Akt activation did not change in RKO cells whereas phospho-Src and phospho-p44/42 mitogen-activated protein kinase was dramatic increased by oxaliplatin. Inhibition of Akt or Src activation with wortmannin or PP2 blocked induction of VEGF-A by oxaliplatin in HT29 or RKO cells, respectively. VEGFRs may reflect the adaptive stress responses by which tumor cells attempt to protect themselves from genotoxic stress. Neutralization of prosurvival responses with anti-VEGF therapy might explain, in part, some of the beneficial effects of anti-VEGF therapy when added to chemotherapy.

Management of bevacizumab-associated bowel perforation: a case series and review of the literature

BACKGROUND

This study examined the various approaches to the management of perforation and the associated outcomes in patients with bevacizumab-associated bowel perforation at a tertiary cancer center.

PATIENTS AND METHODS

Our institutional pharmacy database was searched to identify all patients who had received bevacizumab over a 2-year period (January 2004 to October 2006). Medical records of these patients were examined for reports of confirmed bowel perforation or fistula, associated clinicopathological factors, treatment, and outcomes.

RESULTS

We identified 1442 patients who had been treated with bevacizumab over the study period with perforation occurring in 24 (1.7%). The breakdown of these 24 patients by disease site was as follows: ovarian (3 of 50, 6%), gastroesophageal (2 of 38, 5.3%), pancreatic (7 of 141, 5%), unknown primary (1 of 60, 1.7%), lung (1 of 67, 1.5%), colorectal (6 of 478, 1.3%), and renal cell (4 of 269, 1.5%). The majority of patients (n = 19, 79%) were initially managed nonoperatively. Only five (21%) patients ultimately underwent surgical exploration, with a subsequent anastomotic leak developing in one patient. The overall 30-day mortality rate was 12.5%.

CONCLUSIONS

Bevacizumab-associated bowel perforation occurs in patients with various malignancies, with an incidence of 1.7%. Nonoperative treatment is a viable approach to management in selected patients.

The development and characterization of a human midgut carcinoid cell line

PURPOSE

Gastrointestinal neuroendocrine tumors (NET) are rare heterogeneous tumors that hypersecrete neuropeptides. The scarcity of good gastrointestinal NET models has limited the ability to study potential therapeutic agents. We describe and characterize the establishment of a human midgut carcinoid tumor cell line carcinoid tumor 2 (CNDT2).

EXPERIMENTAL DESIGN

Tumor cells (CNDT2) were isolated from a liver metastasis from a patient with a primary ileal carcinoid. After 9 weeks in culture, the cells were plated in soft agar, and cells from a single colony were put back in culture (CNDT2.1). Those CNDT2.1 cells were injected s.c. into nude mice. Cells were isolated from a single resultant tumor (CNDT2.5), cultured, and characterized by electron microscopy, reverse transcription-PCR, serotonin enzyme immunoassay, Western blotting, and immunohistochemical analysis for NET markers and potential therapeutic targets.

RESULTS

CNDT2 cells grew in monolayers in vitro, formed colonies in soft agar, and formed tumors in mice. Electron microscopy revealed round, pleomorphic, electron-dense neurosecretory granules characteristic of NETs. Tumor xenografts exhibited the appearance of NETs with small "salt-and-pepper" nuclei on H&E staining and chromogranin A, synaptophysin, and CD56 on immunohistochemical staining. CNDT2.5 cells produced serotonin and expressed insulin-like growth factor receptor-I, platelet-derived growth factor receptor-beta, vascular endothelial growth factor receptor-1, cMET, epidermal growth factor receptor, neuropilin-1, and somatostatin receptors 1 to 5. Cytogenetic analysis revealed the presence of deletions at 2p and 6q and numerous translocations.

CONCLUSION

The establishment of this human midgut carcinoid tumor cell line may serve as a useful model system for studying cell biology and novel targeted agents in preclinical models.

Tyrosine kinase receptor RON in human pancreatic cancer: expression, function, and validation as a target

BACKGROUND

Specific tyrosine kinase receptors such as c-MET mediate epithelial-mesenchymal (EMT) transition, leading to phenotypic alterations associated with increased cell motility. It was hypothesized that RON, a tyrosine kinase receptor related to c-MET, would be expressed in human pancreatic cancer cells, induce EMT, and would thus serve as a target for therapy in a preclinical model.

METHODS

RON expression in human pancreatic cancer specimens was assessed by immunohistochemistry. In pancreatic cancer cell lines, RON expression was assessed by reverse-transcriptase polymerase chain reaction (PCR) and Western blot analysis. The human pancreatic cancer cell line L3.6pl, with high RON expression, was exposed to macrophage stimulating protein (MSP), the RON ligand, and assessed for cell migration, invasion, and changes associated with EMT. Western blot analysis and immunofluorescent staining were used to assess alterations in protein expression and cellular location, respectively. A RON monoclonal antibody (MoAb) was used to block ligand-induced activation of RON.

RESULTS

Immunohistochemical staining revealed RON overexpression in 93% of human pancreatic cancer specimens relative to nonmalignant ductal tissue. RON mRNA and protein was expressed in 9 of 9 human pancreatic cancer cell lines. Treatment of L3.6pl cells with MSP increased Erk phosphorylation, cell migration, and invasion (P < .001). RON activation led to a decrease in membrane-bound E-cadherin in association with nuclear translocation of beta-catenin. RON MoAb inhibited downstream signaling as well as cell migration and invasion. In nude mice, RON MoAb inhibited subcutaneous and orthotopic tumor growth by about 60%.

CONCLUSIONS

RON activation induced molecular and cellular alterations consistent with EMT. Inhibition of RON activation inhibited tumor growth in vivo. Novel antineoplastic therapies designed to inhibit RON activity may hinder mechanisms critical for pancreatic tumor progression.

Chronic oxaliplatin resistance induces epithelial-to-mesenchymal transition in colorectal cancer cell lines

PURPOSE

Epithelial-to-mesenchymal transition (EMT) is a process whereby cells acquire molecular alterations that facilitate cell motility and invasion. In preliminary studies, we observed that oxaliplatin-resistant (OxR) colorectal cancer (CRC) cells underwent morphologic changes suggestive of a migratory phenotype, leading us to hypothesize that OxR CRC cells undergo EMT.

EXPERIMENTAL DESIGN

The human CRC cell lines KM12L4 and HT29 were exposed to increasing doses of oxaliplatin to establish stable cell lines resistant to oxaliplatin. Migration and invasion were assessed by modified Boyden chamber assays. Morphologic and molecular changes characteristic of EMT were determined by immunofluorescence staining and Western blot analyses.

RESULTS

The OxR cells showed phenotypic changes consistent with EMT: spindle-cell shape, loss of polarity, intercellular separation, and pseudopodia formation. KM12L4 and HT29 OxR cells exhibited an approximately 8- to 15-fold increase in migrating and invading cells, respectively (P < 0.005 for both). Immunofluorescence staining of OxR cells revealed translocation of E-cadherin and beta-catenin from their usual membrane-bound complex to the cytoplasm and nucleus, respectively. The OxR cells also had decreased expression of the epithelial adhesion molecules E-cadherin and plakoglobin and an increase in the mesenchymal marker vimentin. The KM12L4 OxR cells exhibited increased nuclear expression of Snail, an EMT-regulatory transcription factor, whereas the HT29 OxR cells exhibited an increase in nuclear expression of the EMT-associated transcription factor nuclear factor kappaB.

CONCLUSION

We hypothesize that induction of EMT may contribute to the decreased efficacy of therapy in chemoresistant CRC, as the tumor cells switch from a proliferative to invasive phenotype. Further understanding of the mechanisms of chemoresistance in CRC will enable improvements in chemotherapy for metastatic disease.

Roles of nitric oxide synthase inhibition and vascular endothelial growth factor receptor-2 inhibition on vascular morphology and function in an in vivo model of pancreatic cancer

PURPOSE

Both nitric oxide (NO) and vascular endothelial growth factor (VEGF) mediate tumor vascular function. Because these molecules regulate one another's expression, we hypothesized that NO synthase (NOS) inhibition produces effects comparable to those of anti-VEGF therapy on human pancreatic cancer xenografts.

EXPERIMENTAL DESIGN

L3.6pl human pancreatic cancer cells were s.c. implanted in nude mice. On day 6, mice were randomized to receive (a) PBS (control), (b) DC101 [VEGF receptor 2 (VEGFR-2) antibody] by i.p. injection, (c) N-nitro-l-arginine (NNLA; NOS inhibitor) in the drinking water, or (d) both DC101 and NNLA. Mice were killed on day 20.

RESULTS

DC101 and NNLA as single agents inhibited tumor growth by approximately 50% to 60% (P < 0.008 for both). Furthermore, combined therapy inhibited mean tumor growth by 89% (P < 0.008). Combined inhibition of VEGFR-2 and NOS also decreased mean vessel counts by 65% (P < 0.03) and vessel area by 80% versus controls (P < 0.001). In contrast to DC101 where vessel diameter was similar to control, NNLA decreased mean vessel diameter by 42% (P < 0.001). NNLA also led to a 54% (P < 0.03) decrease in tumor uptake of the perfusion marker Hoechst 33342 versus controls whereas DC101 decreased Hoechst 33342 staining by 43% (P < 0.03). The combination of inhibitors decreased perfusion by 73% (P < 0.03).

CONCLUSIONS

Although VEGFR-2 can mediate NOS activity, the combination of VEGFR-2 and NOS inhibition significantly increased the antivascular effect over single agent therapy. The addition of NOS inhibition led to an even further alteration of tumor vessel morphology and vascular perfusion compared with VEGFR-2 blockade, suggesting that NO and VEGFR-2 have distinct but complementary effects on the tumor vasculature.

The role of nitric oxide in mediating tumour blood flow

Nitric oxide (NO) is a ubiquitous molecule with a myriad of physiological and pathophysiological roles. It has numerous direct and indirect effects on tumour vasculature as both a regulatory and effector molecule. NO affects tumour blood flow through its effects on tumour angiogenesis, vascular tone and vascular permeability, partly via its interaction with vascular endothelial growth factor. In this review, the authors examine the basic tenants of NO biology, the association of NO with tumour progression, and the role NO plays in mediating alterations in vascular functions in tumours.

Vascular endothelial growth factor receptor-1 activation mediates epithelial to mesenchymal transition in human pancreatic carcinoma cells

Our laboratory has shown that vascular endothelial growth factor receptor-1 (VEGFR-1) expression on human pancreatic cancer cell lines mediates cell migration and invasion. Because epithelial to mesenchymal transition (EMT) also plays a role in cell motility by altering the cell phenotype and morphology, we hypothesized that VEGFR-1 activation induces molecular alterations that mediate EMT. Our treatment of the human pancreatic cancer cell line L3.6pl with the VEGFR-1 ligands VEGF-A and VEGF-B led to morphologic changes characteristic of EMT, including loss of polarity, increased intercellular separation, and the presence of pseudopodia. Immunofluorescent staining with antibodies to E-cadherin and beta-catenin showed that VEGFR-1 activation led to translocation of E-cadherin and beta-catenin from their usual cell membrane-bound location to the cytoplasm and nucleus, respectively. Western blotting showed that VEGFR-1 activation led to decreased expression of the epithelial markers E-cadherin and plakoglobin, increased expression of the mesenchymal markers vimentin and N-cadherin, and increased nuclear expression of beta-catenin. Pretreatment of tumor cells with a VEGFR-1 blocking antibody inhibited the VEGFR-1-induced immunohistochemical and molecular changes in E-cadherin. VEGFR-1 activation led to an increase in expression of the EMT-associated transcription factors Snail, Twist, and Slug. The changes mediated by VEGFR-1 in this pancreatic carcinoma cell line are highly consistent with the changes characteristic of EMT. Given our previous finding of VEGFR-1-mediated tumor cell invasion and migration in pancreatic carcinoma cells, we hypothesize that VEGFR-1 plays a role in tumor progression in pancreatic cancer through the induction of EMT.

Minimizing local recurrence after breast conserving therapy using intraoperative shaved margins to determine pathologic tumor clearance

BACKGROUND

This study analyzed survival, locoregional recurrence, and reexcision rates after breast conserving therapy, based on the margin analysis technique used at the University of Florida, which incorporates frozen section analysis of shaved breast tissue from the lumpectomy cavity.

STUDY DESIGN

A retrospective review was done of 257 patients who underwent 267 consecutive lumpectomy operations and completed radiation therapy at our institution. Margins in 189 patients were assessed using frozen section analysis of shaved margins from the lumpectomy cavity.

RESULTS

Breast conserving therapy was performed for 220 (83%) patients with early breast cancer (T1 and T2 tumors) and 47 (17%) with ductal carcinoma in situ. With a median followup of 5.6 years, the crude locoregional recurrence rates for patients who had margins analyzed intraoperatively by frozen section analysis or margins analyzed by permanent analysis were 1.9% (3 of 157) and 3.1% (2 of 63), respectively, for early breast cancer and 15.6% (5 of 32) and 6.6% (1 of 15) for ductal carcinoma in situ (p=NS). Survival rates were 97% and 78%, at 5 and 10 years, respectively, for the early breast cancer patients, and 98% and 98%, respectively, for ductal carcinoma in situ patients. Permanent intraoperative frozen section analysis reexcision rates were 33.3% (26 of 78) and 5.8% (11 of 189).

CONCLUSIONS

Regardless of the technique used for margin analysis, breast conserving therapy led to low locoregional recurrence relative to national figures, pointing to the importance of the technique of radiation therapy at our institution. Reexcision rate was reduced with the use of frozen section analysis.

Improving delivery of antineoplastic agents with anti-vascular endothelial growth factor therapy

It is believed that impairments in delivery of antineoplastic agents to solid tumors result from abnormalities of the tumor microenvironment. Vascular endothelial growth factor (VEGF), the prototypical angiogenic molecule, is one of the main factors responsible for the development and maintenance of the aberrant tumor vascular network, which is characterized by chaotic, leaky blood vessels with high interstitial fluid pressure and inefficient blood flow. The authors proposed that anti-VEGF therapy would reduce the elevated interstitial fluid pressure in tumors, thereby improving blood flow and potentially improving delivery of cytotoxic agents to tumor cells. For the current report, the authors reviewed characteristics of the abnormal tumor vasculature created under the influence of VEGF, the resulting tumor microenvironment, how the tumor microenvironment may impede delivery of antineoplastic agents, and how the combination of anti-VEGF and cytotoxic therapy may maximize the efficacy of antineoplastic treatment regimens.

RON, a Tyrosine Kinase Receptor Involved in Tumor Progression and Metastasis

Tyrosine kinase receptors mediate many critical cellular functions that contribute to tumor progression and metastasis and thus are potential targets for molecular-based cancer therapy. As has been found for many receptor tyrosine kinases, RON (recepteur d'origine nantais) and its ligand, macrophage-stimulating protein, have recently been implicated in the progression and metastasis of tumors. In in vitro experiments using colon and breast cancer cell lines, overexpression of RON led to increased invasion and migration of cancer cells and prevented apoptosis and anoikis. In addition, transgenic mice engineered to overexpress RON in the lung epithelium developed multiple pulmonary tumors, suggesting a role for RON in tumorigenesis. In human cancer specimens, increased RON expression has been demonstrated in colon, breast, ovarian, and lung tumors. Therefore, therapies designed to inhibit RON activation may hinder critical tumor survival mechanisms and play a role in the treatment of advanced disease.