Copper metabolism and cuproptosis in human malignancies: Unraveling the complex interplay for therapeutic insights

Copper, a vital trace element, orchestrates diverse cellular processes ranging from energy production to antioxidant defense and angiogenesis. Copper metabolism and cuproptosis are closely linked in the context of human diseases, with a particular focus on cancer. Cuproptosis refers to a specific type of copper-mediated cell death or copper toxicity triggered by disruptions in copper metabolism within the cells. This phenomenon encompasses a spectrum of mechanisms, such as oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, and perturbations in metal ion equilibrium. Mechanistically, cuproptosis is driven by copper binding to the lipoylated enzymes within the tricarboxylic acid (TCA) cycle. This interaction participates in protein aggregation and proteotoxic stress, ultimately culminating in cell death. Targeting copper metabolism and its associated pathways in cancer cells hold therapeutic potential by selectively targeting and eliminating cancerous cells. Strategies to modulate copper levels, enhance copper excretion, or interfere with cuproptotic pathways are being explored to identify novel therapeutic targets for cancer therapy and improve patient outcomes. Understanding the relationship between cuproptosis and copper metabolism in human malignancies remains an active area of research. This review provides a comprehensive overview of the association among copper metabolism, copper homeostasis, and carcinogenesis, explicitly emphasizing the cuproptosis mechanism and its implications for cancer pathogenesis. Additionally, we emphasize the therapeutic aspects of targeting copper and cuproptosis for cancer treatment.

Epigenetic regulation of bone remodeling and bone metastasis

Bone remodeling is a continuous and dynamic process of bone formation and resorption to maintain its integrity and homeostasis. Bone marrow is a source of various cell lineages, including osteoblasts and osteoclasts, which are involved in bone formation and resorption, respectively, to maintain bone homeostasis. Epigenetics is one of the elementary regulations governing the physiology of bone remodeling. Epigenetic modifications, mainly DNA methylation, histone modifications, and non-coding RNAs, regulate stable transcriptional programs without causing specific heritable alterations. DNA methylation in CpG-rich promoters of the gene is primarily correlated with gene silencing, and histone modifications are associated with transcriptional activation/inactivation. However, non-coding RNAs regulate the metastatic potential of cancer cells to metastasize at secondary sites. Deregulated or altered epigenetic modifications are often seen in many cancers and interwound with bone-specific tropism and cancer metastasis. Histone acetyltransferases, histone deacetylase, and DNA methyltransferases are promising targets in epigenetically altered cancer. High throughput epigenome mapping and targeting specific epigenetics modifiers will be helpful in the development of personalized epi-drugs for advanced and bone metastasis cancer patients. This review aims to discuss and gather more knowledge about different epigenetic modifications in bone remodeling and metastasis. Further, it provides new approaches for targeting epigenetic changes and therapy research.

Immunotherapy: an emerging modality to checkmate brain metastasis

The diagnosis of brain metastasis (BrM) has historically been a dooming diagnosis that is nothing less than a death sentence, with few treatment options for palliation or prolonging life. Among the few treatment options available, brain radiotherapy (RT) and surgical resection have been the backbone of therapy. Within the past couple of years, immunotherapy (IT), alone and in combination with traditional treatments, has emerged as a reckoning force to combat the spread of BrM and shrink tumor burden. This review compiles recent reports describing the potential role of IT in the treatment of BrM in various cancers. It also examines the impact of the tumor microenvironment of BrM on regulating the spread of cancer and the role IT can play in mitigating that spread. Lastly, this review also focuses on the future of IT and new clinical trials pushing the boundaries of IT in BrM.

Abstract 3760: MicroRNA-1 run down the growth and metastasis of small cell lung cancer

Small cell lung cancer (SCLC) is a highly aggressive and metastatic lung cancer subtype with universal relapse and poor prognosis. The lack of potential drug targets limits targeted therapies for SCLC patients. To track down the potential therapeutic molecules in SCLC, we performed micro-RNA sequencing from the serum samples of SCLC patients and compared with the bulk RNA-sequencing data from SCLC tumor tissues. A consistent downregulation of microRNA-1 (miR-1) was observed in the SCLC patient serum samples, cell lines, and tumor tissues compared to their matched normal control. Overexpression of miR-1 in SCLC cell lines decreased cell growth and oncogenic signaling. Metastatic studies using the intracardiac injection model of SCLC cell lines showed that miR-1 overexpression decreases distant organ metastasis. Interestingly, the loss of function studies using miR-1Zip/sponging showed increased tumorigenesis and metastasis in SCLC subcutaneous and intracardiac xenografts. Mechanistic investigations revealed the CXCR4/FOXM1/RRM2 axis as a unique downstream target of miR-1 in SCLC. We found that FOXM1 transcriptionally regulates the RRM2 expression by directly binding to its promoter site, and miR-1 modulates these interactions through CXCR4. The results of the present study provided a strong preclinical rationale that miR-1 has a high potential for developing innovative SCLC therapies.

Citation Format: Parvez Khan, Jawed A. Siddiqui, Shailendra Kumar Maurya, Tamara Mirzapoiazova, Prakash G. Kshirsagar, Ramakanth Chirravuri Venkata, Sanjib Chaudhary, Ranjana Kanchan, Naveenkumar Perumal, Mahek Fatima, Md Arafat Khan, Asad Ur Rehman, Imayavaramban Lakshmanan, Sidharth Mahapatra, Prakash Kulkarni, Apar Kishor Ganti, Maneesh Jain, Ravi Salgia, Surinder Kumar Batra, Mohd Wasim Nasser. MicroRNA-1 run down the growth and metastasis of small cell lung cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3760.

MicroRNA-1 attenuates the growth and metastasis of small cell lung cancer through CXCR4/FOXM1/RRM2 axis

BACKGROUND

Small cell lung cancer (SCLC) is an aggressive lung cancer subtype that is associated with high recurrence and poor prognosis. Due to lack of potential drug targets, SCLC patients have few therapeutic options. MicroRNAs (miRNAs) provide an interesting repertoire of therapeutic molecules; however, the identification of miRNAs regulating SCLC growth and metastasis and their precise regulatory mechanisms are not well understood.

METHODS

To identify novel miRNAs regulating SCLC, we performed miRNA-sequencing from donor/patient serum samples and analyzed the bulk RNA-sequencing data from the tumors of SCLC patients. Further, we developed a nanotechnology-based, highly sensitive method to detect microRNA-1 (miR-1, identified miRNA) in patient serum samples and SCLC cell lines. To assess the therapeutic potential of miR-1, we developed various in vitro models, including miR-1 sponge (miR-1Zip) and DOX-On-miR-1 (Tet-ON) inducible stable overexpression systems. Mouse models derived from intracardiac injection of SCLC cells (miR-1Zip and DOX-On-miR-1) were established to delineate the role of miR-1 in SCLC metastasis. In situ hybridization and immunohistochemistry were used to analyze the expression of miR-1 and target proteins (mouse and human tumor specimens), respectively. Dual-luciferase assay was used to validate the target of miR-1, and chromatin immunoprecipitation assay was used to investigate the protein-gene interactions.

RESULTS

A consistent downregulation of miR-1 was observed in tumor tissues and serum samples of SCLC patients compared to their matched normal controls, and these results were recapitulated in SCLC cell lines. Gain of function studies of miR-1 in SCLC cell lines showed decreased cell growth and oncogenic signaling, whereas loss of function studies of miR-1 rescued this effect. Intracardiac injection of gain of function of miR-1 SCLC cell lines in the mouse models showed a decrease in distant organ metastasis, whereas loss of function of miR-1 potentiated growth and metastasis. Mechanistic studies revealed that CXCR4 is a direct target of miR-1 in SCLC. Using unbiased transcriptomic analysis, we identified CXCR4/FOXM1/RRM2 as a unique axis that regulates SCLC growth and metastasis. Our results further showed that FOXM1 directly binds to the RRM2 promoter and regulates its activity in SCLC.

CONCLUSIONS

Our findings revealed that miR-1 is a critical regulator for decreasing SCLC growth and metastasis. It targets the CXCR4/FOXM1/RRM2 axis and has a high potential for the development of novel SCLC therapies. MicroRNA-1 (miR-1) downregulation in the tumor tissues and serum samples of SCLC patients is an important hallmark of tumor growth and metastasis. The introduction of miR-1 in SCLC cell lines decreases cell growth and metastasis. Mechanistically, miR-1 directly targets CXCR4, which further prevents FOXM1 binding to the RRM2 promoter and decreases SCLC growth and metastasis.

Emerging role of chemokines in small cell lung cancer: Road signs for metastasis, heterogeneity, and immune response

Small cell lung cancer (SCLC) is a recalcitrant, relatively immune-cold, and deadly subtype of lung cancer. SCLC has been viewed as a single or homogenous disease that includes deletion or inactivation of the two major tumor suppressor genes (TP53 and RB1) as a key hallmark. However, recent sightings suggest the complexity of SCLC tumors that comprises highly dynamic multiple subtypes contributing to high intratumor heterogeneity. Furthermore, the absence of targeted therapies, the understudied tumor immune microenvironment (TIME), and subtype plasticity are also responsible for therapy resistance. Secretory chemokines play a crucial role in immunomodulation by trafficking immune cells to the tumors. Chemokines and cytokines modulate the anti-tumor immune response and wield a pro-/anti-tumorigenic effect on SCLC cells after binding to cognate receptors. In this review, we summarize and highlight recent findings that establish the role of chemokines in SCLC growth and metastasis, and sophisticated intratumor heterogeneity. We also discuss the chemokine networks that are putative targets or modulators for augmenting the anti-tumor immune responses in targeted or chemo-/immuno-therapeutic strategies, and how these combinations may be utilized to conquer SCLC.

Chemokines and cytokines: Axis and allies in prostate cancer pathogenesis

Chemokines are recognized as the major contributor to various tumorigenesis, tumor heterogeneity, and failures of current cancer therapies. The tumor microenvironment (TME) is enriched with chemokines and cytokines and plays a pivotal role in cancer progression. Chronic inflammation is also considered an instructive process of cancer progression, where chemokines are spatiotemporally secreted by malignant cells and leukocyte subtypes that initiate cell trafficking into the TME. In various cancers, prostate cancer (PCa) is reported as one of the leading cancers in the worldwide male population. The chemokines-mediated signaling pathways are intensively involved in PCa progression and metastasis. Emerging evidence suggests that chemokines and cytokines are responsible for the pleiotropic actions in cancer, including the growth, angiogenesis, endothelial mesenchymal transition, leukocyte infiltration, and hormone escape for advanced PCa and therapy resistance. Chemokine's system and immune cells represent a promising target to suppress tumorigenic environments and serve as potential therapy/immunotherapy for the PCa. In this review, an attempt has been made to shed light on the alteration of chemokine and cytokine profiles during PCa progression and metastasis. We also discussed the recent findings of the diverse molecular signaling of these circulating chemokines and their corresponding receptors that could become future targets for therapeutic management of PCa.

Chemokines network in bone metastasis: Vital regulators of seeding and soiling

Chemokines are well equipped with chemo-attractive signals that can regulate cancer cell trafficking to specific organ sites. Currently, updated concepts have revealed the diverse role of chemokines in the biology of cancer initiation and progression. Genomic instabilities and alterations drive tumor heterogeneity, providing more options for the selection and metastatic progression to cancer cells. Tumor heterogeneity and acquired drug resistance are the main obstacles in managing cancer therapy and the primary root cause of metastasis. Studies emphasize that multiple chemokine/receptor axis are involved in cancer cell-mediated organ-specific distant metastasis. One of the persuasive mechanisms for heterogeneity and subsequent events is sturdily interlinked with the crosstalk between chemokines and their receptors on cancer cells and tissue-specific microenvironment. Among different metastatic niches, skeletal metastasis is frequently observed in the late stages of prostate, breast, and lung cancer and significantly reduces the survival of cancer patients. Therefore, it is crucial to elucidate the role of chemokines and their receptors in metastasis and bone remodeling. Here, we review the potential chemokine/receptor axis in tumorigenesis, tumor heterogeneity, metastasis, and vicious cycle in bone microenvironment.

Abstract 1489: MicroRNA-1 targets CXCR4/FOXM1/RRM2 axis regulating small cell lung cancer growth and metastasis

Small cell lung cancer (SCLC) is a high-grade neuroendocrine metastatic lung cancer subtype having a universal relapse and poor prognosis. Limited or extensive-stage SCLC patients have limited therapeutic options due to a lack of potential drug targets. In the quest for novel therapeutic molecules, we performed micro-RNA sequencing from the serum samples and also analyzed bulk RNA-sequencing data from tumors of SCLC patients. We found a consistent downregulation of miR-1 in SCLC. These results were recapitulated in SCLC cell lines and tumor tissues compared to their matched normal. To assess the therapeutic potential of miR-1, we overexpressed miR-1 in SCLC cell lines that translated into decreased cell growth and oncogenic signaling. Mechanistic studies revealed that CXCR4 is a direct target for miR-1 in SCLC. Intracardiac injection of SCLC cell lines in the mouse models showed that overexpression of miR-1 decreases the distant organ metastasis, whereas miR-1 sponging potentiates aggressiveness and metastasis. Furthermore, we identified FOXM1-RRM2 as a unique downstream target of the miR-1/CXCR4 axis involved in the growth and metastasis of SCLC. Our results showed that FOXM1 directly binds to the promoter site of RRM2 and regulates its activity. Overexpression of miR-1 decreases the expression and activity of FOXM1-RRM2 through CXCR4 that reduces cell growth and metastasis. Taken together, our results suggest that miR-1 decreases SCLC metastasis by targeting the CXCR4/FOXM1-RRM2 axis and has a high potential for the development of novel SCLC therapies.

Citation Format: Parvez Khan, Jawed A. Siddiqui, Shailendra Kumar Maurya, Tamara Mirzapoiazova, Ranjana Kanchan, Ramakanth Chirravuri Venkata, Pranita Atri, Wemin Tang, NaveenKumar Perumal, Prakash Kshirsagar, Mahek Fatima, Md Arafat Khan, Sanjib Chaudhary, Asad Ur Rehman, Imayavaramban Lakshmanan, Sidharth Mahapatra, Prakash Kulkarni, Apar Kishor Ganti, Maneesh Jain, David Oupicky, Ravi Salgia, Surinder Kumar Batra, Mohd Wasim Nasser. MicroRNA-1 targets CXCR4/FOXM1/RRM2 axis regulating small cell lung cancer growth and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1489.

Molecular mechanisms of pancreatic myofibroblast activation in chronic pancreatitis and pancreatic ductal adenocarcinoma

Pancreatic fibrosis (PF) is an essential component of the pathobiology of chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC). Activated pancreatic myofibroblasts (PMFs) are crucial for the deposition of the extracellular matrix, and fibrotic reaction in response to sustained signaling. Consequently, understanding of the molecular mechanisms of PMF activation is not only critical for understanding CP and PDAC biology but is also a fertile area of research for the development of novel therapeutic strategies for pancreatic pathologies. This review analyzes the key signaling events that drive PMF activation including, initiating signals from transforming growth factor-β1, platelet derived growth factor, as well as other microenvironmental cues, like hypoxia and extracellular matrix rigidity. Further, we discussed the intracellular signal events contributing to PMF activation, and crosstalk with different components of tumor microenvironment. Additionally, association of epidemiologically established risk factors for CP and PDAC, like alcohol intake, tobacco exposure, and metabolic factors with PMF activation, is discussed to comprehend the role of lifestyle factors on pancreatic pathologies. Overall, this analysis provides insight into the biology of PMF activation and highlights salient features of this process, which offer promising therapeutic targets.

MicroRNA-1: Diverse role of a small player in multiple cancers

The process of cancer initiation and development is a dynamic and complex mechanism involving multiple genetic and non-genetic variations. With the development of high throughput techniques like next-generation sequencing, the field of cancer biology extended beyond the protein-coding genes. It brought the functional role of noncoding RNAs into cancer-associated pathways. MicroRNAs (miRNAs) are one such class of noncoding RNAs regulating different cancer development aspects, including progression and metastasis. MicroRNA-1 (miR-1) is a highly conserved miRNA with a functional role in developing skeletal muscle precursor cells and cardiomyocytes and acts as a consistent tumor suppressor gene. In humans, two discrete genes, MIR-1-1 located on 20q13.333 and MIR-1-2 located on 18q11.2 loci encode for a single mature miR-1. Downregulation of miR-1 has been demonstrated in multiple cancers, including lung, breast, liver, prostate, colorectal, pancreatic, medulloblastoma, and gastric cancer. A vast number of studies have shown that miR-1 affects the hallmarks of cancer like proliferation, invasion and metastasis, apoptosis, angiogenesis, chemosensitization, and immune modulation. The potential therapeutic applications of miR-1 in multiple cancer pathways provide a novel platform for developing anticancer therapies. This review focuses on the different antitumorigenic and therapeutic aspects of miR-1, including how it regulates tumor development and associated immunomodulatory functions.

RNA-based therapies: A cog in the wheel of lung cancer defense

Lung cancer (LC) is a heterogeneous disease consisting mainly of two subtypes, non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), and remains the leading cause of death worldwide. Despite recent advances in therapies, the overall 5-year survival rate of LC remains less than 20%. The efficacy of current therapeutic approaches is compromised by inherent or acquired drug-resistance and severe off-target effects. Therefore, the identification and development of innovative and effective therapeutic approaches are critically desired for LC. The development of RNA-mediated gene inhibition technologies was a turning point in the field of RNA biology. The critical regulatory role of different RNAs in multiple cancer pathways makes them a rich source of targets and innovative tools for developing anticancer therapies. The identification of antisense sequences, short interfering RNAs (siRNAs), microRNAs (miRNAs or miRs), anti-miRs, and mRNA-based platforms holds great promise in preclinical and early clinical evaluation against LC. In the last decade, RNA-based therapies have substantially expanded and tested in clinical trials for multiple malignancies, including LC. This article describes the current understanding of various aspects of RNA-based therapeutics, including modern platforms, modifications, and combinations with chemo-/immunotherapies that have translational potential for LC therapies.

Epigenetic landscape of small cell lung cancer: small image of a giant recalcitrant disease

Small cell lung cancer (SCLC) is a particular subtype of lung cancer with high mortality. Recent advances in understanding SCLC genomics and breakthroughs of immunotherapy have substantially expanded existing knowledge and treatment modalities. However, challenges associated with SCLC remain enigmatic and elusive. Most of the conventional drug discovery approaches targeting altered signaling pathways in SCLC end up in the 'grave-yard of drug discovery', which mandates exploring novel approaches beyond inhibiting cell signaling pathways. Epigenetic modifications have long been documented as the key contributors to the tumorigenesis of almost all types of cancer, including SCLC. The last decade witnessed an exponential increase in our understanding of epigenetic modifications for SCLC. The present review highlights the central role of epigenetic regulations in acquiring neoplastic phenotype, metastasis, aggressiveness, resistance to chemotherapy, and immunotherapeutic approaches of SCLC. Different types of epigenetic modifications (DNA/histone methylation or acetylation) that can serve as predictive biomarkers for prognostication, treatment stratification, neuroendocrine lineage determination, and development of potential SCLC therapies are also discussed. We also review the utility of epigenetic targets/epidrugs in combination with first-line chemotherapy and immunotherapy that are currently under investigation in preclinical and clinical studies. Altogether, the information presents the inclusive landscape of SCLC epigenetics and epidrugs that will help to improve SCLC outcomes.

Abstract 3021: Plexin-B3 regulates cellular motility, invasiveness and metastasis in pancreatic cancer

Cancer metastasis significantly worsens the survival of pancreatic cancer (PC) patients. Currently, semaphorins and their high-affinity receptors plexins are considered versatile regulators of cancer cell migration, angiogenesis, invasion and metastasis. Our group identified semaphorin-5A (SEMA5A) as a putative cell adhesion molecule involved in organ-specific homing of PC cells and playing a significant role in PC angiogenesis and metastasis. Thus, SEMA5A and its receptor plexin-B3 represents an attractive targetable axis in PC metastasis. However, for a better understanding of the SEMA5A-initiated downstream signaling events and regulation of cellular phenotypes, it is necessary to delineate the function of its receptor plexin-B3 in PC as well. Thus, understanding the pathologic expression and functional role of plexin-B3 is essential for characterization of SEMA5A/plexin-B3 axis in PC. In the present study, we analyzed plexin-B3 expression in PC disease progression model of PDX-Cre-Kras(G12D) (KC) mice and evaluated the functional role by utilizing plexin-B3 knockdown T3M-4 and CD18/HPAF cells. We observed a reduction of plexin-B3 expression with disease progression in KC mice model and also the poor survival of pancreatic adenocarcinoma stage II patients (n = 24) with lower plexin-B3 expression. Functionally, knockdown of plexin-B3 enhanced in vitro cellular migration and invasiveness of PC cells. Furthermore, plexin-B3 knockdown cells showed a significant increase in cellular size with impaired colony formation in three-dimensional culture. Cell proliferation analysis demonstrated that plexin-B3 knockdown cells showed lower proliferation in comparison with the control cells. We also observed higher metastasis with lower tumor burden in nude mice injected with CD18/HPAF-sh plexin-B3 cells than CD18/HPAF-control cells. Furthermore, the tumors formed by CD18/HPAF-plexin-B3 cells showed higher fibrosis, a higher number of vimentin-positive cells, and lower number of proliferation marker Ki-67-positive cells in comparison with the CD18/HPAF-control tumors. In addition, we observed similar phenotypic changes in PC cells with loss of SEMA5A-ligand of plexin-B3. In summary, our data demonstrate that impairment in SEMA5A/plexin-B3 axis enhances cellular motility and invasiveness of PC cells, thereby resulting in higher metastasis.

Citation Format: Sugandha Saxena, Yuri Hayashi, Satyanarayana Rachagani, Surinder Kumar Batra, Rakesh Kumar Singh. Plexin-B3 regulates cellular motility, invasiveness and metastasis in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3021.

Loss of claudin-3 expression induces IL6/gp130/Stat3 signaling to promote colon cancer malignancy by hyperactivating Wnt/β-catenin signaling

The Hyperactivated Wnt/β-catenin signaling acts as a switch to induce EMT and promote colorectal cancer. However, due to its essential role in gut homeostasis, therapeutic targeting of this pathway has proven challenging. Additionally, IL-6/Stat-3 signaling, activated by microbial translocation through the dysregulated mucosal barrier in colon adenomas, facilitates the adenoma to adenocarcinomas transition. However, inter-dependence between these signaling pathways and key mucosal barrier components in regulating colon tumorigenesis and cancer progression remains unclear. In current study, we have discovered, using a comprehensive investigative regimen, a novel and tissue specific role of claudin-3, a tight junction integral protein, in inhibiting colon cancer progression by serving as the common rheostat of Stat-3 and Wnt-signaling activation. Loss of claudin-3 also predicted poor patient survival. These findings however contrasted an upregulated claudin-3 expression in other cancer types and implicated role of the epigenetic regulation. Claudin-3−/− mice revealed dedifferentiated and leaky colonic epithelium, and developed invasive adenocarcinoma when subjected to colon cancer. Wnt-signaling hyperactivation, albeit in GSK-3β independent manner, differentiated colon cancer in claudin-3−/− mice versus WT-mice. Claudin-3 loss also upregulated the gp130/IL6/Stat3 signaling in colonic epithelium potentially assisted by infiltrating immune components. Genetic and pharmacological studies confirmed that claudin-3 loss induces Wnt/β-catenin activation, which is further exacerbated by Stat-3-activation and help promote colon cancer. Overall, these novel findings identify claudin-3 as a therapeutic target for inhibiting overactivation of Wnt-signaling to prevent CRC malignancy.

Abstract 2691: Cigarette smoke induced upregulation of endothelin axis in the initiation of pancreatic cancer

Background: Cigarette smoke is an established risk factor for pancreatic ductal adenocarcinoma (PDAC). Smoke induced inflammation accelerates the progression of PDAC in presence of constitutively active K-Ras mutation. Endothelin (ET) axis comprising of endothelin converting enzymes (ECE-1, ECE-2, and ECE-3), endothelin isoforms (ET-1, ET-2 and ET-3) and two receptors A (ETAR) and B (ETBR), is linked to pathobiology of pancreatitis and its components exhibit aberrant overexpression in PDAC. However, the expression of ET-axis in the oncogene-associated early Pancreatic Intraepithelial neoplastic (PanINs) lesions following exposure to cigarette smoke is unknown. We hypothesize that smoke induced alterations in the ET axis facilitate acinar to ductal metaplasia (ADM) in presence of oncogenic K-Ras. Thus, we characterized the impact of cigarette smoke exposure on ET axis components in the pancreas of mice harboring mutant K-Ras.

Methods: Expression of ECE-1, ET-1, ETAR and ETBR was analyzed by IHC and RT-PCR first in the murine model of preneoplastic lesions [KC model: (Pdx1-Cre, KrasG12D)). To determine the changes in ET axis after smoke exposure, wild type (WT) and KC mutant mice were exposed to cigarette smoke for 20 weeks and expression was analyzed in the pancreas. The impact of smoking on ET-axis was also studied on murine acinar and tumor cell lines derived from KC mice (UN-KC6141) and KPC (Pdx1-Cre, p53 (R172H) KrasG12D) mice (UN-KPC-961) by western blot and RT-PCR analysis.

Results: In contrast to the normal ducts, the expression of ECE-1, ET-1, ETAR and ETBR was upregulated in the early PaNIN lesions (20-30 weeks). In the advanced lesions (50 weeks), significant overexpression of all four molecules was noticeable in the tumor cells and stromal compartment. Smoke exposure resulted in significant increase in the transcripts of ET-1, ETAR and ETBR (p values = 0.04, 0.03 and 0.01 respectively) in the KC mice while the increase in WT mice was not significant. The changes in the expression were also corroborated by tissue IHC. Expression of ET axis components was predominantly seen in the islet cells in WT mice, while low immunoreactivity was observed in the acinar compartment. Smoke exposure of KC mice resulted in accelerated progression of PanIN lesions along with concomitant increase in the expression of ET axis components both in the ductal and stromal cells. In vitro exposure of cigarette smoke extract (CSE) to UN-KC6141 and UN-KPC-961 cells for 24 hours elicited a dose dependent upregulation of ECE 1 and ET-1.

Conclusions: In presence of mutated KrasG12D, smoking-mediated inflammatory insult promotes PanIN progression and tumorigenesis. The sustained increase and activation of ET axis with increasing dysplasia in the ductal compartment during this progression in KC mice and its further upregulation following smoke exposure suggests its possible role in promoting inflammation-associated pancreatic tumor progression.

Citation Format: Suprit Gupta, Satyanarayana Rachagani, Sushil Kumar, Surinder Kumar Batra, Maneesh Jain. Cigarette smoke induced upregulation of endothelin axis in the initiation of pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2691. doi:10.1158/1538-7445.AM2017-2691

Gut permeability and mucosal inflammation: bad, good or context dependent

Inflammatory bowel disease (IBD) is a multifactorial disease. A breach in the mucosal barrier, otherwise known as "leaky gut," is alleged to promote mucosal inflammation by intensifying immune activation. However, interaction between the luminal antigen and mucosal immune system is necessary to maintain mucosal homeostasis. Furthermore, manipulations leading to deregulated gut permeability have resulted in susceptibility in mice to colitis as well as to creating adaptive immunity. These findings implicate a complex but dynamic association between mucosal permeability and immune homeostasis; however, they also emphasize that compromised gut permeability alone may not be sufficient to induce colitis. Emerging evidence further supports the role(s) of proteins associated with the mucosal barrier in epithelial injury and repair: manipulations of associated proteins also modified epithelial differentiation, proliferation, and apoptosis. Taken together, the role of gut permeability and proteins associated in regulating mucosal inflammatory diseases appears to be more complex than previously thought. Herein, we review outcomes from recent mouse models where gut permeability was altered by direct and indirect effects of manipulating mucosal barrier-associated proteins, to highlight the significance of mucosal permeability and the non-barrier-related roles of these proteins in regulating chronic mucosal inflammatory conditions.

Abstract 2495: hPaf1/PD2 interacts with OCT3/4 in maintenance of the self-renewal process of ovarian cancer stem cells

Background: Ovarian cancer (OC) is the most lethal gynecological malignancy among women with more than 85% of the patients manifesting tumor recurrence. Emerging evidence suggests that a small population of cells within the tumor - the ‘cancer stem cells (CSCs)’ is capable to giving rise to the entire histopathology of the tumor and is responsible for mediating drug resistance, recurrence, and disease aggressiveness. Previously, hPaf1(human RNA polymerase II associated factor1)/PD2 (Pancreatic Differentiation2) - a core component of RNA polymerase II associated factor (PAF) complex, was shown to be overexpressed in pancreatic CSCs and involved in the maintenance of mouse ESCs. Hence, we hypothesized that hPaf1 is involved in the maintenance of self-renewal property of ovarian CSCs (OCSCs). In this study, we investigated the functional role of hPaf1 in OCSCs which has not been explored before.

Methods: Expression of hPaf1, cancer stem cell marker ESA, and self-renewal protein OCT3/4 was analyzed using confocal microscopy on OC tissue array. Side population (SP) was isolated from two OC cell lines OVCAR3 and A2780 by Hoechst staining using flow-cytometer, and characterized using tumor sphere assay. Immunoblotting was performed on characterized SP and NSP (non-SP) for OCSC and self-renewal markers. Transient knockdown of hPaf1 in SP was performed to understand how hPaf1 affects the CSC phenotype through immunoblotting, confocal microscopy, colony formation assay, and tumor sphere formation assay. To determine the interaction between hPaf1 and OCT 3/4, reciprocal co-immunoprecipitation was performed in SP/OCSCs.

Results: There was a significant overexpression and considerable co-localization of hPaf1/PD2 with ESA and OCT3/4 in OC tissues compared to normal ovary tissues. SP from OVCAR3 formed larger and greater number of tumor spheres compared to NSP cells. Moreover, SP isolated from OVCAR3 and A2780 showed higher expression of hPaf1 along with CSC markers (CD44, CD133, ESA, CD24), and self- renewal proteins (β-CATENIN, SOX2, OCT3/4, SHH, and HER2). Transient knockdown of hPaf1 resulted in a significant decrease in expression of CSC markers and self-renewal proteins. In addition, functional characteristics of CSCs such as in vitro tumor formation capacity in non-adherent media and colony formation ability were impaired upon knockdown of hPaf1 suggesting that hPaf1 is involved in maintenance of the CSC phenotype. We also observed that hPaf1 physically interacts with OCT3/4 in OVCAR3 SP cells which provides a mechanism for the maintenance of OCSCs by hPaf1.

Conclusion: Altogether, hPaf1/PD2 is overexpressed in OCSCs and its knockdown resulted in loss of OCSC phenotype. Moreover, hPaf1 is responsible for the maintenance of OCSCs through its interaction with OCT3/4. Hence, therapies that are able to abrogate hPaf1 mediated self-renewal of OCSCs represent potential therapeutic avenues to overcome tumor relapse in OC.

Citation Format: Saswati Karmakar, Parthasarathy Seshacharyulu, Arokia Priyanka Vaz, Imayavaramban Lakshmanan, Moorthy Palanimuthu Ponnusamy, Surinder Kumar Batra. hPaf1/PD2 interacts with OCT3/4 in maintenance of the self-renewal process of ovarian cancer stem cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2495.

Abstract 4191: Alterations in endothelin axis during pancreatic acinar to ductal metaplasia

Background: Acinar-ductal-metaplasia (ADM) is one the earliest recognizable alterations in the tumorigenesis of pancreatic ductal adenocarcinoma (PDAC). Inflammation-induced ADM, which is typically reversible upon removal of inflammatory insult, becomes irreversible in the presence of oncogenic K-Ras and progresses to Pancreatic Intraepithelial neoplastic lesions (PanINs) and subsequently PDAC. Endothelin (ET) axis comprising of endothelin isoforms (ET-1, ET-2 and ET-3) and two receptors A (ETAR) and B (ETBR), has been demonstrated to contribute to the pathobiology of pancreatitis and its components exhibit aberrant overexpression in pancreatic cancer PDAC. However, the expression patterns of ET axis in oncogene-associated early lesions remain unknown. We hypothesize that alterations in ET axis contribute to oncogene associated irreversible ADM. Thus, we studied expression pattern of ET axis in the pancreatic inflammation in the presence and absence of oncogenic KRas and in preneoplastic lesions.

Methods: Expression of ET-1, ETAR and ETBR was analyzed in murine models of preneoplastic lesions [KC model: (Pdx1-Cre, KrasG12D)) by IHC. To determine the changes in ET axis during ADM, wild type (WT) and KC mutant mice were treated with cerulein to induce pancreatitis and tissues collected at day 0, 2, 7 and 21 days post treatment were analyzed for mRNA and Immunofluorescence analysis. Expression pattern of ET axis components was also determined in the pancreas of KC and WT animals following exposure to cigarette smoke.

Results: A progressive increase in the expression of ET-1, ETAR and ETBR was observed in the PanIN lesions in KC mice. In mice with WT Kras, cerulein treatment resulted in a notable increase in the expression of ET-1 and ETAR at day 2, while the levels of ETBR increased marginally; however a recovery to basal levels was observed for all three molecules by day 7. In contrast, significant increase (p<0.005) in ET-1, ETAR and ETBR transcripts was observed following cerulein treatment and these levels continued to remain high even at 21 days post-trauma in KC mice. The changes in the expression ETAR and ETBR were corroborated by confocal microscopy. Cerulein treatment resulted in increased expression of ETAR and ETBR in acinar compartment in both WT and KC mice as indicated by their co-localization with amylase. In KC mice, cerulein induced acinar-to-ductal metaplasia and the resulting CK19 positive ductal components continued to express increased levels of both receptors with distinct magnitude and kinetics. Similarly, in the smoking models, ET-axis components exhibited a more robust and sustained overexpression in KC mice as compared to the WT.

Conclusions: The expression of oncogenic KrasG12D results in an enhanced and sustained activation of ET-axis following inflammatory insults in the pancreatic tissues, suggesting its possible role in tumor initiation and progression.

Citation Format: Suprit Gupta, Satyanarayana Rachagani, Sushil Kumar, Kavita Mallya, Surinder Kumar Batra, Maneesh Jain. Alterations in endothelin axis during pancreatic acinar to ductal metaplasia. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4191.

RAC1 GTPase promotes the survival of breast cancer cells in response to hyper-fractionated radiation treatment

Radiation therapy is a staple approach for cancer treatment, whereas radioresistance of cancer cells remains a substantial clinical problem. In response to ionizing radiation (IR) induced DNA-damage, cancer cells can sustain/activate pro-survival signaling pathways, leading to apoptotic resistance and induction of cell cycle checkpoint/DNA repair. Previous studies show that Rac1 GTPase is overexpressed/hyperactivated in breast cancer cells and is associated with poor prognosis. Studies from our laboratory reveal that Rac1 activity is necessary for G2/M checkpoint activation and cell survival in response to IR exposure of breast and pancreatic cancer cells. In the present study, we investigated the effect of Rac1 on the survival of breast cancer cells treated with hyper-fractionated radiation (HFR), which is used clinically for cancer treatment. Results in this report indicate that Rac1 protein expression is increased in the breast cancer cells that survived HFR compared to parental cells. Furthermore, this increase of Rac1 is associated with enhanced activities of ERK1/2 and NF-κB signaling pathways and increased levels of anti-apoptotic protein Bcl-xL and Mcl-1, which are downstream targets of ERK1/2 and NF-κB signaling pathways. Using Rac1 specific inhibitor and dominant negative mutant N17Rac1, here we demonstrate that Rac1 inhibition decreases the phosphorylation of ERK1/2 and IκBα, as well as the levels of Bcl-xL and Mcl-1 protein in the HFR-selected breast cancer cells. Moreover, inhibition of Rac1 using either small molecule inhibitor or dominant negative N17Rac1 abrogates clonogenic survival of HFR-selected breast cancer cells and decreases the level of intact PARP, which is indicative of apoptosis induction. Collectively, results in this report suggest that Rac1 signaling is essential for the survival of breast cancer cells subjected to HFR and implicate Rac1 in radioresistance of breast cancer cells. These studies also provide the basis to explore Rac1 as a therapeutic target for radioresistant breast cancer cells.

Hypoxia-induced oxidative stress promotes MUC4 degradation via autophagy to enhance pancreatic cancer cells survival

Pancreatic cancer (PC) and associated pre-neoplastic lesions have been reported to be hypoxic, primarily due to hypovascular nature of PC. Though the presence of hypoxia under cancerous condition has been associated with the overexpression of oncogenic proteins (MUC1), multiple emerging reports have also indicated the growth inhibitory effects of hypoxia. In spite of being recognized as the top-most differentially expressed and established oncogenic protein in PC, MUC4 regulation in terms of micro-environmental stress has not been determined. Herein, for the first time, we are reporting that MUC4 protein stability is drastically affected in PC, under hypoxic condition in a hypoxia inducible factor 1α (HIF-1α)-independent manner. Mechanistically, we have demonstrated that hypoxia-mediated induction of reactive oxygen species (ROS) promotes autophagy by inhibiting pAkt/mTORC1 pathway, one of the central regulators of autophagy. Immunohistofluorescence analyses revealed significant negative correlation (P-value=0.017) between 8-hydroxy guanosine (8-OHG) and MUC4 in primary pancreatic tumors (n=25). Moreover, we found pronounced colocalization between MUC4 and LAMP1/LC3 (microtubule-associated protein 1A/1B-light chain 3) in PC tissues and also observed their negative relationship in their expression pattern, suggesting that areas with high autophagy rate had less MUC4 expression. We also found that hypoxia and ROS have negative impact on overall cell growth and viability, which was partially, though significantly (P<0.05), rescued in the presence of MUC4. Altogether, hypoxia-mediated oxidative stress induces autophagy in PC, leading to the MUC4 degradation to enhance survival, possibly by offering required metabolites to stressed cells.

MUC5AC interactions with integrin β4 enhances the migration of lung cancer cells through FAK signaling

MUC5AC is a secretory mucin aberrantly expressed in various cancers. In lung cancer, MUC5AC is overexpressed in both primary and metastatic lesions; however, its functional role is not well understood. The present study was aimed at evaluating mechanistic role of MUC5AC on metastasis of lung cancer cells. Clinically, the overexpression of MUC5AC was observed in lung cancer patient tissues and was associated with poor survival. In addition, the overexpression of Muc5ac was also observed in genetically engineered mouse lung adenocarcinoma tissues (Kras(G12D); Trp53(R172H/+); AdCre) in comparison with normal lung tissues. Our functional studies showed that MUC5AC knockdown resulted in significantly decreased migration in two lung cancer cell lines (A549 and H1437) as compared with scramble cells. Expression of integrins (α5, β1, β3, β4 and β5) was decreased in MUC5AC knockdown cells. As both integrins and MUC5AC have a von Willebrand factor domain, we assessed for possible interaction of MUC5AC and integrins in lung cancer cells. MUC5AC strongly interacted only with integrin β4. The co-localization of MUC5AC and integrin β4 was observed both in A549 lung cancer cells as well as genetically engineered mouse adenocarcinoma tissues. Activated integrins recruit focal adhesion kinase (FAK) that mediates metastatic downstream signaling pathways. Phosphorylation of FAK (Y397) was decreased in MUC5AC knockdown cells. MUC5AC/integrin β4/FAK-mediated lung cancer cell migration was confirmed through experiments utilizing a phosphorylation (Y397)-specific FAK inhibitor. In conclusion, overexpression of MUC5AC is a poor prognostic marker in lung cancer. MUC5AC interacts with integrin β4 that mediates phosphorylation of FAK at Y397 leading to lung cancer cell migration.

Mice deficient in Muc4 are resistant to experimental colitis and colitis-associated colorectal cancer

MUC4, a large transmembrane mucin normally expressed in the small and large intestine, is differentially expressed during inflammatory and malignant conditions of the colon. However, the expression pattern and the role of MUC4 in colitis and colorectal cancer (CRC) are inconclusive. Therefore, the aim of this study was to understand the role of Muc4 during inflammatory and malignant conditions of the colon. Here, we generated Muc4(-/-) mice and addressed its role in colitis and colitis-associated CRC using dextran sodium sulfate (DSS) and azoxymethane (AOM)-DSS experimental models, respectively. Muc4(-/-) mice were viable, fertile with no apparent defects. Muc4(-/-) mice displayed increased resistance to DSS-induced colitis compared with wild-type (WT) littermates that was evaluated by survival rate, body weight loss, diarrhea and fecal blood score, and histological score. Reduced infiltration of inflammatory cells, that is, CD3(+) lymphocytes and F4/80(+) macrophages was observed in the inflamed mucosa along with reduction in the mRNA levels of inflammatory cytokines interleukin (IL)-1β and tumor necrosis factor (TNF)-α and anti-microbial genes Lysozyme M and SLPI in the colon of Muc4(-/-) mice compared with WT littermates. Compensatory upregulation of Muc2 and Muc3 mucins under basal and DSS treatment conditions partly explains the resistance observed in Muc4(-/-) mice. Accordingly, Muc4(-/-) mice exhibited significantly reduced tumor burden compared with WT mice assessed in a colitis-induced tumor model using AOM/DSS. An increased percentage of Ki67(+) nuclei was observed in the tumors from WT compared with Muc4(-/-) mice suggesting Muc4 to be critical in intestinal cell proliferation during tumorigenesis. Taken together, we conclusively demonstrate for the first time the role of Muc4 in driving intestinal inflammation and inflammation-associated tumorigenesis using a novel Muc4(-/-) mouse model.

Abstract 4983: GALNT3 mediated differential MUC4 glycosylation in the progression of pancreatic cancer

Purpose: MUC4 is one of the membrane-bound mucins that is expressed de novo during pancreatic cancer (PC) and contributes to pathogenesis. Further, MUC4 is aberrantly glycosylated in PC and some of its tumor-promoting effects are, in part, mediated by interactions facilitated by the glycan epitopes, which are generally masked under normal conditions. Mucins predominantly undergo O-glycosylation that is initiated by a family of enzymes known as GALNTs (UDP-N-acetyl-α-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase), catalyzing the transfer of first sugar residue (GalNAc) to ser/thr residues in mucin tandem repeat domains. Not much is known about the specific glycosyltransferases (GTs) involved in MUC4 glycosylation. Understanding the specific enzymes regulating differential glycosylation of MUC4 in cancer may be important for developing therapeutic strategies for modulating MUC4 function in PC. Thus, the goal of this study was to identify specific GALNT(s) catalyzing MUC4 glycosylation and investigate its role in differential MUC4 glycosylation in PC.

Materials & Methods: PCR array analysis was performed in a panel of MUC4 expressing and non-expressing PC cell lines, normal pancreatic cancer cells and MUC4 expressing normal colon cells to identify differentially expressed GTs. To determine the altered glycosylation of MUC4 in normal versus cancerous conditions, Co-immunoprecipitation (Co-IP) studies were conducted using several carbohydrate-specific antibodies. Stable knockdown of GALNT3 was performed in PC and normal colon cells to understand its involvement in differential MUC4 glycosylation. To determine the functional implications of GALNT3 mediated aberrant glycosylation, various in vitro assays such as colony formation and migration were carried out.

Results: PCR array and immunoblot analysis demonstrated GALNT3 as one of the GTs upregulated in MUC4 expressing cells as compared to MUC4 non-expressing PC cells. Interestingly, Co-IP analysis revealed differential expression of carbohydrates epitopes such as STn, SLex, SLea on MUC4 in PC and normal colon cells. GALNT3 knockdown in cancer cells resulted in decreased expression of Tn but simultaneous increase in STn epitope. Interestingly, we observed significant increase in colony formation and migration in GALNT3 knockdown cells. This was associated with increase in proliferation and EMT markers in GALNT3 knockdown PC cells such as N-cadherin, vimentin and phosphorylated ErbBs.

Conclusion: Overall, our results suggested a correlation of MUC4 and GALNT3 expression, and knockdown of GALNT3 resulted in altered MUC4 glycosylation rather than complete abrogation, suggesting a possible compensatory increase in other GALNTs and other GTs. Further investigations along these lines will provide insight into specific GTs regulating MUC4 glycosylation and glycan epitope-mediated MUC4 functions in cancer.

Citation Format: Seema Chugh, Vinayaga Srinivasan Gnanapragassam, Maneesh Jain, Moorthy Ponnusamy, Surinder Kumar Batra. GALNT3 mediated differential MUC4 glycosylation in the progression of pancreatic cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4983. doi:10.1158/1538-7445.AM2015-4983

Novel role of pancreatic differentiation 2 in facilitating self-renewal and drug resistance of pancreatic cancer stem cells

BACKGROUND

Cancer stem cells (CSCs) contribute towards disease aggressiveness and drug resistance. Specific identification of CSC maintenance genes and targeting can improve the efficiency of currently available treatment modalities. Pancreatic differentiation 2 (PD2) has a major role in the self-renewal of mouse embryonic stem cells. In the present study, we investigated the role of PD2 in pancreatic CSCs.

METHODS

Characterisation of CSCs and non-CSCs from mouse models, pancreatic cancer cells and human tissues by CSC and self-renewal marker analysis using confocal assay. Effect of PD2 knockdown in CSCs (after gemcitabine treatment) was studied by immunoblot and apoptosis assays.

RESULTS

A subpopulation of cells displayed PD2 overexpression in mouse (Kras(G12D); Pdx1-Cre and Kras(G12D); Trp53(R172H/+); Pdx1-Cre) and human pancreatic tumours, which co-express CSC markers. Cancer stem cells exhibited elevated expression of PD2 and self-renewal markers, such as Oct3/4, Shh and β-catenin. Gemcitabine treatment maintained the CSC population with simultaneous maintenance of PD2 and CSC marker expression. Knockdown of PD2 in CSCs resulted in reduced viability of cells and enhanced apoptosis along with abrogated expression of CD133 and MDR2.

CONCLUSIONS

Our results suggest that PD2 is a novel CSC maintenance protein, loss of which renders the CSCs more susceptible to drug-induced cell death.

Secreted semaphorin 5A suppressed pancreatic tumour burden but increased metastasis and endothelial cell proliferation

Background:

Our earlier reports demonstrated that membrane-bound semaphorin 5A (SEMA5A) is expressed in aggressive pancreatic cancer cells and tumours, and promotes tumour growth and metastasis. In this study, we examine whether (1) pancreatic cancer cells secrete SEMA5A and (2) that secreted SEMA5A modulates certain phenotypes associated with tumour progression, angiogenesis and metastasis through various other molecular factors and signalling proteins.

Methods and results:

In this study, we show that human pancreatic cancer cell lines secrete the extracellular domain (ECD) of SEMA5A (SEMA5A-ECD) and overexpression of mouse Sema5A-ECD in Panc1 cells (not expressing SEMA5A; Panc1-Sema5A-ECD; control cells - Panc1-control) significantly increases their invasion in vitro via enhanced ERK phosphorylation. Interestingly, orthotopic injection of Panc1-Sema5A-ECD cells into athymic nude mice results in a lower primary tumour burden, but enhances the micrometastases to the liver as compared with Panc1-control cells. Furthermore, there is a significant increase in proliferation of endothelial cells treated with conditioned media (CM) from Panc1-Sema5A-ECD cells and a significant increase in microvessel density in Panc1-Sema5A-ECD orthotopic tumours compared with those from Panc1-control cells, suggesting that the increase in liver micrometastases is probably due to increased tumour angiogenesis. In addition, our data demonstrate that this increase in endothelial cell proliferation by Sema5A-ECD is mediated through the angiogenic molecules – interleukin-8 and vascular endothelial growth factor.

Conclusion:

Taken together, these results suggest that a bioactive, secreted form of Sema5A-ECD has an intriguing and potentially important role in its ability to enhance pancreatic tumour invasiveness, angiogenesis and micrometastases.

Activated KrasG¹²D is associated with invasion and metastasis of pancreatic cancer cells through inhibition of E-cadherin

Background:

Pancreatic cancer (PC) harbours an activated point mutation (Kras^G12D) in the Kras proto-oncogene that has been demonstrated to promote the development of PC.

Methods:

This study was designed to investigate the effect of the oncogenic Kras^G12D allele on aggressiveness and metastatic potential of PC cells. We silenced the oncogenic Kras^G12D allele expression in CD18/HPAF and ASPC1 cell lines by stable expression of shRNA specific to the Kras^G12Dallele.

Results:

The Kras^G12D knockdown cells exhibited a significant decrease in motility (P<0.0001), invasion (P<0.0001), anchorage-dependent (P<0.0001) and anchorage-independent growth (P<0.0001), proliferation (P<0.005) and an increase in cell doubling time (P<0.005) in vitro and a decrease in the incidence of metastases upon orthotopic implantation into nude mice. The knockdown of the Kras^G12D allele led to a significant increase in the expression of E-cadherin (mRNA and protein) both in vitro and in vivo. This was associated with a decrease in the expression of phoshpo-ERK-1/2, NF-κB and MMP-9, and transcription factors such as δEF1, Snail and ETV4. Furthermore, the expression of several proteins involved in cell survival, invasion and metastasis was decreased in the Kras^G12D knockdown cells.

Conclusions:

The results of this study suggest that the Kras^G12D allele promotes metastasis in PC cells partly through the downregulation of E-cadherin.

New advances on critical implications of tumor- and metastasis-initiating cells in cancer progression, treatment resistance and disease recurrence

Accumulating lines of experimental evidence have revealed that the malignant transformation of multipotent tissue-resident adult stem/progenitor cells into cancer stem/progenitor cells endowed with a high self-renewal capacity and aberrant multilineage differentiation potential may be at origin of the most types of human aggressive and recurrent cancers. Based on new cancer stem/progenitor cell concepts of carcinogenesis, it is suggested that a small subpopulation of highly tumorigenic and migrating cancer stem/progenitor cells, also designated as cancer- and metastasis-initiating cells, can provide critical roles for primary tumor growth, metastases at distant tissues and organs, treatment resistance and disease relapse. Particularly, cancer initiation and progression to locally invasive and metastatic stages is often associated with a persistent activation of distinct developmental signaling pathways in these immature cells during epithelial-mesenchymal transition program. The signaling cascades that are often deregulated in cancer stem/progenitor cells include hedgehog, epidermal growth factor receptor (EGFR), Wnt/beta-catenin, NOTCH, polycomb gene product BMI-1 and/or stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor 4 (CXCR4). Importantly, the results from recent investigations have also indicated that different cancer subtypes may harbor distinct subsets and/or number of cancer-initiating cells during cancer progression as well as before or after therapy initiation and disease recurrence. Therefore, the identification of the molecular transforming events that frequently occur in cancer- and metastasis-initiating cells versus their differentiated progenies is of immense interest to develop new targeting approach for improving current therapies against aggressive, metastatic, recurrent and lethal cancers.

Membrane-bound mucins: the mechanistic basis for alterations in the growth and survival of cancer cells

Mucins (MUC) are high molecular weight O-linked glycoproteins whose primary functions are to hydrate, protect, and lubricate the epithelial luminal surfaces of the ducts within the human body. The MUC family is comprised of large secreted gel forming and transmembrane (TM) mucins. MUC1, MUC4, and MUC16 are the well-characterized TM mucins and have been shown to be aberrantly overexpressed in various malignancies including cystic fibrosis, asthma, and cancer. Recent studies have uncovered the unique roles of these mucins in the pathogenesis of cancer. These mucins possess specific domains that can make complex associations with various signaling pathways, impacting cell survival through alterations of cell growth, proliferation, death, and autophagy. The cytoplasmic domain of MUC1 serves as a scaffold for interaction with various signaling proteins. On the other hand, MUC4 mediates its effect by stabilizing and enhancing the activity of growth factor receptor ErbB2. MUC16, previously known as CA125, is a well-known serum marker for the diagnosis of ovarian cancer and has a key role in stimulation and dissemination of ovarian cancer cells by interacting with mesothelin and galectin. Therefore, herein we discuss the function and divergent mechanisms of MUC1, MUC4, and MUC16 in carcinogenesis in the context of alteration in cell growth and survival.

Immunopathogenesis of ovarian cancer

Ovarian cancer, the most aggressive gynecologic cancer, is the foremost cause of death from gynecologic malignancies in the developed world. Over 90% of ovarian cancers arise from the surface epithelium, which are classified as epithelial ovarian cancer (EOC). EOCs can be categorized as serous, mucinous, endometrioid, clear cell, and transitional cell types. The molecular pathology of ovarian carcinomas is heterogeneous and involves various putative precursor lesions and multiple pathways of development. Furthermore, in another aspect, immune deficiencies that are present in the ovarian tumor environment enhance the progression of the tumor in the host. The presence of regulatory T cells, the inhibition of natural killer cytotoxic responses, the accumulation of myeloid suppressor cells in the tumor, deficiencies on interferon signaling, the secretion of cytokines that enhance tumor growth (i.e., IL-6, IL-10, CSF-1, TGF-b, TNF), and the expression of surface molecules (i.e., HLA-G, B7-H1, B7-H4, CD40, CD80) that have a role on immune suppression, are discussed in detail. The aim of this review is to provide insight of the evidence that supports the role of immunodeficiency in the progression of ovarian cancer and future directions for ovarian cancer therapies. It also discusses the genetic alterations in the subtypes of ovarian cancers.

Aging of tissue-resident adult stem/progenitor cells and their pathological consequences

The fascinating discovery of tissue-resident adult stem/progenitor cells in recent years led to an explosion of interest in the development of novel stem cell-based therapies for improving the regenerative capacity of these endogenous immature cells or transplanted cells for the repair of damaged and diseased tissues. In counterbalance, a growing body of evidence has revealed that the changes in phenotypic and functional properties of human adult stem/progenitor cells may occur during chronological aging and have severe pathological consequences. Especially, intense oxidative and metabolic stress and chronic inflammation, enhanced telomere attrition and defects in DNA repair mechanisms may lead to severe DNA damages and genomic instability in adult stem/progenitor cells with advancing age that may in turn trigger their replicative senescence and/or programmed cell death. Moreover, the changes in the intrinsic and extrinsic factors involved in the stringent control of self-renewal and multilineage differentiation capacities of these regenerative cells, including deregulated signals from the aged niche, may also contribute to their dysfunctions or loss during chronological aging. This age-associated decline in the regenerative capacity and number of functional adult stem/progenitor cells may increase the risk to develop certain diseases. At opposed end, the telomerase reactivation and accumulation of genetic alterations leading to a down-regulation of numerous tumor suppressor genes concomitant with the enhanced expression of diverse oncogenic products may result in their malignant transformation into cancer-initiating cells. Therefore, the rescue or replacement of aged and dysfunctional endogenous adult stem/progenitor cells or molecular targeting of their malignant counterpart, cancer stem/progenitor cells may constitute potential anti-aging and cancer therapies. These therapeutic strategies could be used for treating diverse devastating premature aging and age-related disorders including hematopoietic and immune disorders, heart failure and cardiovascular diseases, neurodegenerative, muscular and gastrointestinal diseases, atherosclerosis and aggressive and lethal cancers.

Deregulation of MUC4 in gastric adenocarcinoma: potential pathobiological implication in poorly differentiated non-signet ring cell type gastric cancer

MUC4 is a large, heavily glycosylated transmembrane mucin, that is implicated in the pathogenesis of various types of cancers. To date, no extensive study has been done to check the expression and functional significance of MUC4 in different types of gastric adenocarcinomas. Here, we report the expression profile of MUC4 in gastric adenocarcinomas and its function in poorly differentiated gastric non-signet ring cell carcinoma (non-SRCC) type cells. Immunohistochemical analysis using tissue microarray (TMA) showed a significant difference in MUC4 expression between normal adjacent (n=45) and gastric adenocarcinoma (n=83; P<0.001). MUC4 expression was not associated with tumour type, stage or with the degree of differentiation. To gain further insight into the significance of MUC4 expression in gastric non-SRCC cells, MUC4 was ectopically expressed in AGS, a poorly differentiated gastric non-signet ring cell line. The MUC4 overexpressing cells (AGS-MUC4) showed a significant increase (P<0.005) in cell motility and a decrease in cellular aggregation as compared with the vector-transfected cells. Furthermore, in vivo tumorigenicity analysis revealed that animals transplanted with the MUC4 overexpressing cells (AGS-MUC4) had a greater incidence of tumours (83%) in comparison to empty vector control (17%). In addition, the expression of MUC4 resulted in enhanced expression of total cellular ErbB2 and phosphorylated ErbB2. In conclusion, our results showed that MUC4 is overexpressed in gastric adenocarcinoma tissues, and that it has a role in promoting aggressive properties in poorly differentiated gastric non-SRCC cells through the activation of the ErbB2 oncoprotein.

Recent progress on normal and malignant pancreatic stem/progenitor cell research: therapeutic implications for the treatment of type 1 or 2 diabetes mellitus and aggressive pancreatic cancer

Recent progress on pancreatic stem/progenitor cell research has revealed that the putative multipotent pancreatic stem/progenitor cells and/or more committed beta cell precursors may persist in the pancreatic gland in adult life. The presence of immature pancreatic cells with stem cell-like properties offers the possibility of stimulating their in vivo expansion and differentiation or to use their ex vivo expanded progenies for beta cell replacement-based therapies for type 1 or 2 diabetes mellitus in humans. In addition, the transplantation of either insulin-producing beta cells derived from embryonic, fetal and other tissue-resident adult stem/progenitor cells or genetically modified adult stem/progenitor cells may also constitute alternative promising therapies for treating diabetic patients. The genetic and/or epigenetic alterations in putative pancreatic adult stem/progenitor cells and/or their early progenies may, however, contribute to their acquisition of a dysfunctional behaviour as well as their malignant transformation into pancreatic cancer stem/progenitor cells. More particularly, the activation of distinct tumorigenic signalling cascades, including the hedgehog, epidermal growth factor-epidermal growth factor receptor (EGF-EGFR) system, wingless ligand (Wnt)/beta-catenin and/or stromal cell-derived factor-1 (SDF-1)-CXC chemokine receptor 4 (CXCR4) pathways may play a major role in the sustained growth, survival, metastasis and/or drug resistance of pancreatic cancer stem/progenitor cells and their further differentiated progenies. The combination of drugs that target the oncogenic elements in pancreatic cancer stem/progenitor cells and their microenvironment, with the conventional chemotherapeutic regimens, could represent promising therapeutic strategies. These novel targeted therapies should lead to the development of more effective treatments of locally advanced and metastatic pancreatic cancers, which remain incurable with current therapies.

Early diagnosis of pancreatic cancer: neutrophil gelatinase-associated lipocalin as a marker of pancreatic intraepithelial neoplasia

Pancreatic cancer is a highly lethal malignancy with a dismal 5-year survival of less than 5%. The scarcity of early biomarkers has considerably hindered our ability to launch preventive measures for this malignancy in a timely manner. Neutrophil gelatinase-associated lipocalin (NGAL), a 24-kDa glycoprotein, was reported to be upregulated nearly 27-fold in pancreatic cancer cells compared to normal ductal cells in a microarray analysis. Given the need for biomarkers in the early diagnosis of pancreatic cancer, we investigated the expression of NGAL in tissues with the objective of examining if NGAL immunostaining could be used to identify foci of pancreatic intraepithelial neoplasia, premalignant lesions preceding invasive cancer. To examine a possible correlation between NGAL expression and the degree of differentiation, we also analysed NGAL levels in pancreatic cancer cell lines with varying grades of differentiation. Although NGAL expression was strongly upregulated in pancreatic cancer, and moderately in pancreatitis, only a weak expression could be detected in the healthy pancreas. The average composite score for adenocarcinoma (4.26+/-2.44) was significantly higher than that for the normal pancreas (1.0) or pancreatitis (1.0) (P<0.0001). Further, although both well- and moderately differentiated pancreatic cancer were positive for NGAL, poorly differentiated adenocarcinoma was uniformly negative. Importantly, NGAL expression was detected as early as the PanIN-1 stage, suggesting that it could be a marker of the earliest premalignant changes in the pancreas. Further, we examined NGAL levels in serum samples. Serum NGAL levels were above the cutoff for healthy individuals in 94% of pancreatic cancer and 62.5% each of acute and chronic pancreatitis samples. However, the difference between NGAL levels in pancreatitis and pancreatic cancer was not significant. A ROC curve analysis revealed that ELISA for NGAL is fairly accurate in distinguishing pancreatic cancer from non-cancer cases (area under curve=0.75). In conclusion, NGAL is highly expressed in early dysplastic lesions in the pancreas, suggesting a possible role as an early diagnostic marker for pancreatic cancer. Further, serum NGAL measurement could be investigated as a possible biomarker in pancreatitis and pancreatic adenocarcinoma.

Targeting of cancer stem/progenitor cells plus stem cell-based therapies: the ultimate hope for treating and curing aggressive and recurrent cancers

The rapid progression from aggressive primary cancers into locally advanced and invasive and/or metastatic diseases remains a big obstacle for an early diagnosis and curative therapeutic intervention for cancer patients. The late-stage leukemias and disseminated and metastatic sarcomas, melanomas, brain tumors and epithelial cancers are the devastating diseases associated with a high rate of recurrence after treatment with the conventional clinical therapies including surgery, ionizing radiation, hormonal therapy and systemic chemotherapy, which generally lead to the death of patients. Therefore, the establishment of the molecular events underlying cancer initiation and progression into locally invasive and metastatic diseases is of major interest in basic cancer research as well as for the development of new effective clinical therapeutic options against the recurrent and lethal cancers. Recent advances have led to the identification of specific oncogenic products that are implicated in the malignant transformation of adult stem/progenitor cells into leukemic or tumorigenic and migrating cancer stem/progenitor cells during cancer progression. Of therapeutic interest, the molecular targeting of deregulated signaling elements in cancer stem/progenitor cells and their local microenvironment represents a new potential strategy for the development of more effective clinical treatments against aggressive cancers. Particularly, the combined use of chemotherapeutic drugs to eradicate cancer-initiating cells with hematopoietic stem cell or genetically-modified stem cell transplant is emerging as potential cancer treatments that hold great promise in the area of clinical cancer research. These targeting and stem cell-based therapies may offer the ultimate hope for treating and even curing the patients diagnosed with locally advanced cancers at high risk of recurrence, metastatic and/or relapsed cancers in the clinics.

Recent advances in cancer stem/progenitor cell research: therapeutic implications for overcoming resistance to the most aggressive cancers

Overcoming intrinsic and acquired resistance of cancer stem/progenitor cells to current clinical treatments represents a major challenge in treating and curing the most aggressive and metastatic cancers. This review summarizes recent advances in our understanding of the cellular origin and molecular mechanisms at the basis of cancer initiation and progression as well as the heterogeneity of cancers arising from the malignant transformation of adult stem/progenitor cells. We describe the critical functions provided by several growth factor cascades, including epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR), stem cell factor (SCF) receptor (KIT), hedgehog and Wnt/beta-catenin signalling pathways that are frequently activated in cancer progenitor cells and are involved in their sustained growth, survival, invasion and drug resistance. Of therapeutic interest, we also discuss recent progress in the development of new drug combinations to treat the highly aggressive and metastatic cancers including refractory/relapsed leukaemias, melanoma and head and neck, brain, lung, breast, ovary, prostate, pancreas and gastrointestinal cancers which remain incurable in the clinics. The emphasis is on new therapeutic strategies consisting of molecular targeting of distinct oncogenic signalling elements activated in the cancer progenitor cells and their local microenvironment during cancer progression. These new targeted therapies should improve the efficacy of current therapeutic treatments against aggressive cancers, and thereby preventing disease relapse and enhancing patient survival.

Recent advances on the molecular mechanisms involved in the drug resistance of cancer cells and novel targeting therapies

This review summarizes the recent knowledge obtained on the molecular mechanisms involved in the intrinsic and acquired resistance of cancer cells to current cancer therapies. We describe the cascades that are often altered in cancer cells during cancer progression that may contribute in a crucial manner to drug resistance and disease relapse. The emphasis is on the implication of ATP-binding cassette (ABC) multidrug efflux transporters in drug disposition and antiapoptotic factors, including epidermal growth factor receptor cascades and deregulated enzymes in ceramide metabolic pathways. The altered expression and activity of these signaling elements may have a critical role in the resistance of cancer cells to cytotoxic effects induced by diverse chemotherapeutic drugs and cancer recurrence. Of therapeutic interest, new strategies for reversing the multidrug resistance and developing more effective clinical treatments against the highly aggressive, metastatic, and recurrent cancers, based on the molecular targeting of the cancer progenitor cells and their further differentiated progeny, are also described.

Stem cells: a revolution in therapeutics-recent advances in stem cell biology and their therapeutic applications in regenerative medicine and cancer therapies

Basic and clinical research accomplished during the last few years on embryonic, fetal, amniotic, umbilical cord blood, and adult stem cells has constituted a revolution in regenerative medicine and cancer therapies by providing the possibility of generating multiple therapeutically useful cell types. These new cells could be used for treating numerous genetic and degenerative disorders. Among them, age-related functional defects, hematopoietic and immune system disorders, heart failures, chronic liver injuries, diabetes, Parkinson's and Alzheimer's diseases, arthritis, and muscular, skin, lung, eye, and digestive disorders as well as aggressive and recurrent cancers could be successfully treated by stem cell-based therapies. This review focuses on the recent advancements in adult stem cell biology in normal and pathological conditions. We describe how these results have improved our understanding on critical and unique functions of these rare sub-populations of multipotent and undifferentiated cells with an unlimited self-renewal capacity and high plasticity. Finally, we discuss some major advances to translate the experimental models on ex vivo and in vivo expanded and/or differentiated stem cells into clinical applications for the development of novel cellular therapies aimed at repairing genetically altered or damaged tissues/organs in humans. A particular emphasis is made on the therapeutic potential of different tissue-resident adult stem cell types and their in vivo modulation for treating and curing specific pathological disorders.

Human MUC4 mucin induces ultra-structural changes and tumorigenicity in pancreatic cancer cells

MUC4 is a type-1 transmembrane glycoprotein and is overexpressed in many carcinomas. It is a heterodimeric protein of 930 kDa, composed of a mucin-type subunit, MUC4α, and a membrane-bound growth factor-like subunit, MUC4β. MUC4 mRNA contains unique 5′ and 3′ coding sequences along with a large variable number of tandem repeat (VNTR) domain of 7–19 kb. A direct association of MUC4 overexpression has been established with the degree of invasiveness and poor prognosis of pancreatic cancer. To understand the precise role of MUC4 in pancreatic cancer, we engineered a MUC4 complementary DNA construct, mini-MUC4, whose deduced protein (320 kDa) is comparable with that of wild-type MUC4 (930 kDa) but represents only 10% of VNTR. Stable ectopic expression of mini-MUC4 in two human pancreatic cancer cell lines, Panc1 and MiaPaCa, showed that MUC4 minigene expression follows a biosynthesis and localisation pattern similar to the wild-type MUC4. Expression of MUC4 resulted in increased growth, motility, and invasiveness of the pancreatic cancer cells in vitro. Ultra-structural examination of MUC4-transfected cells showed the presence of increased number and size of mitochondria. The MUC4-expressing cells also demonstrated an enhanced tumorigenicity in an orthotopic xenograft nude mice model, further supporting a direct role of MUC4 in inducing the cancer properties. In conclusion, our results suggest that MUC4 promotes tumorigenicity and is directly involved in growth and survival of the cancer cells.

Human RNA polymerase II-associated factor complex: dysregulation in cancer

Genetic instabilities are believed to be one of the major causes of developing a cancer phenotype in humans. During the progression of cancer, aberrant expression of proteins, either owing to genetic (amplification, mutation and deletion) or epigenetic modifications (DNA methylation and histone deacetylation), contributes in different ways to the development of cancer. By differential screening analysis, an amplification of the 19q13 locus containing a novel pancreatic differentiation 2 (PD2) gene was identified. PD2 is the human homolog of the yeast RNA polymerase II-associated factor 1 (yPaf1) and is part of the human RNA polymerase II-associated factor (hPAF) complex. hPAF is comprised of five subunits that include PD2/hPaf1, parafibromin, hLeo1, hCtr9 and hSki8. This multifaceted complex was first identified in yeast (yPAF) and subsequently in Drosophila and human. Recent advances in the study on PAF have revealed various functions of the complex in human, which are similar to yPAF, including efficient transcription elongation, mRNA quality control and cell-cycle regulation. Although the precise function of this complex in cancer is not clearly known, some of its subunits have been linked to a malignant phenotype. Its core subunit, PD2/hPaf1, is amplified and overexpressed in many cancers. Further, an overexpression of PD2/hPaf1 results in the induction of a transformed phenotype, suggesting its possible involvement in tumorigenesis. The parafibromin subunit of the hPAF complex is a product of the HRPT-2 (hereditary hyperparathyroidism type 2) tumor suppressor gene, which is mutated in the germ line of hyperparathyroidism-jaw tumor patients. This review focuses on the functions of the PAF complex and its individual subunits, the interaction of the subunits with each other and/or with other molecules, and dysregulation of the complex, providing an insight into its potential involvement in the development of cancer.

IFN-gamma-induced expression of MUC4 in pancreatic cancer cells is mediated by STAT-1 upregulation: a novel mechanism for IFN-gamma response

MUC4 is a transmembrane mucin, which is aberrantly expressed in pancreatic adenocarcinoma with no detectable expression in the normal pancreas. Here, we present a novel mechanism of IFN-gamma-induced expression of MUC4 in pancreatic cancer cells. Our studies highlight the upregulation of STAT-1 as a basis for MUC4 induction and demonstrate that its activation and upregulation by IFN-gamma are two distinct, albeit temporally integrated, signalling events that drive the selective induction of IRF-1 and MUC4, respectively, within a single cell system. The profile of interferon regulatory factor (IRF)-1 gene induction by IFN-gamma is consistent with its rapid transactivation by phospho-Y701-STAT-1. In contrast, the induction of the MUC4 mucin gene expression is relatively delayed, and occurs only in response to an increase in STAT-1 expression. A progressive binding of STAT-1 to various gamma-interferon-activated sequences (GAS) in the MUC4 promoter is observed in chromatin immunoprecipitation assay, indicating its direct association. Stimulation of STAT-1 expression by double-stranded polynucleotides or ectopic expression is shown to induce MUC4 expression, without Y701 phosphorylation of STAT-1. This effect is abrogated by short interfering RNA (siRNA)-mediated inhibition of STAT-1 expression, supporting further the relevance of STAT-1 in MUC4 regulation. In conclusion, our findings identify a novel mechanism for MUC4 regulation in pancreatic cancer cells and unfold new perspectives on the foundation of IFN-gamma-dependent gene regulation.

Interplay of distinct growth factors during epithelial mesenchymal transition of cancer progenitor cells and molecular targeting as novel cancer therapies

In this review, we describe the critical functions assumed by the interplay of epidermal growth factor, hedgehog, Wnt/beta-catenin, tumor growth factor-beta and integrin signaling cascades in tumorigenic and migrating cancer progenitor cells and activated stromal cells during carcinogenesis. These growth factors provide an important role for the sustained growth and survival of tumorigenic cancer progenitor cells and their progeny by up-regulating numerous mitotic and antiapoptotic signaling cascades. Furthermore, these potent morphogens may cooperate for inducing the molecular events associated with the epithelial-mesenchymal program in cancer cells including the alterations in epithelial cell shape and motility through the dissociation of intercellular adherens junctions. Of therapeutic interest, new strategies for the development of more effective clinical treatments against the locally aggressive and invasive cancers based on the molecular targeting of deregulated signaling elements in tumorigenic and migrating cancer cells and their local microenvironment are also described.

MUC4 expression is regulated by cystic fibrosis transmembrane conductance regulator in pancreatic adenocarcinoma cells via transcriptional and post-translational mechanisms

MUC4 mucin is a high molecular weight transmembrane glycoprotein that plays important roles in tumour biology. It is aberrantly expressed in pancreatic adenocarcinoma, while not being detectable in the normal pancreas. Previous studies have demonstrated that the cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel that is defective in CF, is implicated in multiple cellular functions, including gene regulation. In the present study, using a CFTR-defective pancreatic cancer cell line and its derived subline expressing functional CFTR, we report that MUC4 expression is negatively regulated by CFTR. Short-interfering RNA (siRNA)-mediated silencing of CFTR also leads to an increased expression of MUC4. Additionally, our results suggest that CFTR-mediated regulation of MUC4 is cell density-dependent and is achieved by transcriptional and posttranslational mechanisms. Moreover, in a panel of pancreatic cancer cell lines and normal pancreas, we observed that CFTR was downregulated in pancreatic cancer cells and negatively correlated with MUC4 in most cases. An aberrant expression of MUC4 was also detected in the CF pancreas. Downregulation of CFTR in pancreatic adenocarcinoma and its inverse association with the tumour-linked mucin, MUC4, indicate novel function(s) of CFTR in pancreatic tumour biology and suggest the implication of new signalling pathway(s) in MUC4 regulation.

The human homologue of the RNA polymerase II-associated factor 1 (hPaf1), localized on the 19q13 amplicon, is associated with tumorigenesis

The 19q13 amplicon in pancreatic cancer cells contains a novel pancreatic differentiation 2 (PD2) gene (accession number AJ401156), which was identified by differential screening analysis. PD2 is the human homologue of the RNA polymerase II-associated factor 1 (hPaf1). In yeast, Paf1 is part of the transcription machinery, acting as a docking protein in between the complexes Rad6-Bre1, COMPASS-Dot1p, and the phosphorylated carboxyl terminal domain of the RNA polymerase II. As such, Paf1 is directly involved in transcription elongation via histone H2B ubiquitination and histone H3 methylation. The PD2 sequence is highly conserved from Drosophila to humans with up to 98% identity between rodent and human, suggesting the functional importance of PD2/hPaf1 to maintain cellular homeostasis. PD2 is a modular protein composed of RNA recognition motif, DEAD-boxes, an aspartic/serine (DS)-domain, a regulator of the chromosome condensation domain and myc-type helix-loop-helix domains. Our results further showed that PD2 is a nuclear 80 kDa protein, which interacts with RNA polymerase II. In addition, we have demonstrated that the overexpression of PD2 in the NIH 3T3 cells result in enhanced growth rates in vitro and tumor formation in vivo. Altogether, this paper presents strong evidence that the overexpression of PD2/hPaf1 is involved in cancer development.

MUC4 expression is a novel prognostic factor in patients with invasive ductal carcinoma of the pancreas

BACKGROUND

Many patients with invasive ductal carcinoma of the pancreas (IDC) have a poor outcome. MUC4 expression has been implicated as a marker for diagnosis and progression of IDC, but there are no studies of the relation between MUC4 expression and patient prognosis in IDC.

AIMS

To investigate the prognostic significance of MUC4 expression in IDC.

METHODS

The expression profiles of MUC4, ErbB2, p27, and MUC1 were investigated in IDC tissues from 135 patients by means of immunohistochemistry.

RESULTS

MUC4 was expressed in 43 of the 135 patients with IDC (31.9%). The survival of 21 patients with high MUC4 expression (>20% of neoplastic cells stained) was significantly worse than that of the 114 patients with low MUC4 expression (<20% of neoplastic cells stained) (p = 0.0043). Univariate analysis showed that high MUC4 expression (p = 0.0061), large primary tumour status (>T2) (p = 0.0436), distant metastasis (p = 0.0383), lymphatic invasion (p = 0.0243), and surgical margins (p = 0.0333) were significant risk factors affecting the outcome of patients with IDC. Backward stepwise multivariate analysis showed that MUC4 expression (p = 0.0121), lymph node metastasis (p = 0.0245), and lymphatic invasion (p = 0.0239) were significant independent risk factors. ErbB2, p27, and MUC1 were not independent risk factors.

CONCLUSIONS

This study shows that MUC4 expression in IDC is a new independent factor for poor prognosis and predicts the outcome of patients with IDC.

Multiple roles of mucins in pancreatic cancer, a lethal and challenging malignancy

Mucins are members of an expanding family of large multifunctional glycoproteins. Pancreatic mucins have important biological functions, including the protection, lubrication, and moisturisation of the surfaces of epithelial tissues lining ductal structures within the pancreas. Several lines of evidence support the notion that deregulated mucin production is a hallmark of inflammatory and neoplastic disorders of the pancreas. Herein, we discuss the factors that contribute to the lethality of pancreatic cancer as well as the key role played by mucins, particularly MUC1 and MUC4, in the development and progression of the disease. Aspects pertaining to the aberrant expression and glycosylation of mucins are discussed, with special emphasis on their potential impact on the design and implementation of adequate diagnostic and therapeutic strategies for combating this lethal malignancy.