The identification of auto-antibodies in pancreatic cancer patient sera using a naturally fractionated Panc-1 cell line

Plasma cells in human pancreatic ductal adenocarcinoma secrete antibodies against self-antigens

Intratumoral B cell responses are associated with more favorable clinical outcomes in human pancreatic ductal adenocarcinoma (PDAC). However, the antigens driving these B cell responses are largely unknown. We sought to discover these antigens by using single-cell RNA sequencing (scRNA-Seq) and immunoglobulin (Ig) sequencing of tumor-infiltrating immune cells from 7 primary PDAC samples. We identified activated T and B cell responses and evidence of germinal center reactions. Ig sequencing identified plasma cell (PC) clones expressing isotype-switched and hypermutated Igs, suggesting the occurrence of T cell-dependent B cell responses. We assessed the reactivity of 41 recombinant antibodies that represented the products of 235 PCs and 12 B cells toward multiple cell lines and PDAC tissues and observed frequent staining of intracellular self-antigens. Three of these antigens were identified: the filamentous actin (F-actin), the nucleic protein RuvB like AAA ATPase 2 (RUVBL2), and the mitochondrial protein heat shock protein family D (Hsp60) member 1 (HSPD1). Antibody titers against F-actin and HSPD1 were substantially elevated in the plasma of patients with PDAC compared with healthy donors. Thus, PCs in PDAC produce autoantibodies reacting with intracellular self-antigens, which may result from promotion of preexisting, autoreactive B cell responses. These observations indicate the chronic inflammatory microenvironment of PDAC can support the adaptive immune response.

KIF15 is essential for USP10-mediated PGK1 deubiquitination during the glycolysis of pancreatic cancer

Glycolysis is the most predominant metabolic reprogramming of pancreatic cancer (PC), the underlying mechanism of which in PC cells remains unclear. In this study, we found for the first time that KIF15 promotes the glycolytic capacity of PC cells and PC tumor growth. Moreover, the expression of KIF15 was negatively correlated with the prognosis of PC patients. The ECAR and OCR measurements indicated that KIF15 knockdown significantly impaired the glycolytic capacity of PC cells. Western blotting demonstrated that the expression of glycolysis molecular markers decreased rapidly after the knockdown of KIF15. Further experiments revealed that KIF15 promoted the stability of PGK1 and its effect on PC cell glycolysis. Interestingly, the overexpression of KIF15 impaired the ubiquitination level of PGK1. To investigate the underlying mechanism by which KIF15 regulates the function of PGK1, we performed mass spectrometry (MS). The MS and Co-IP assay indicated that KIF15 recruited and enhanced the binding between PGK1 and USP10. The ubiquitination assay verified that KIF15 recruited and promoted the effect of USP10 on PGK1, thereby deubiquitinating PGK1. Through the construction of KIF15 truncators, we found that KIF15 is bound to PGK1 and USP10 through its coil2 domain. Together, our study demonstrated for the first time that KIF15 enhances the glycolytic capacity of PC through the recruitment of USP10 and PGK1, and that the KIF15/USP10/PGK1 axis may serve as an effective therapeutic agent for PC.

B-Lymphocytes in the Pathophysiology of Pancreatic Adenocarcinoma

Pancreatic adenocarcinoma is highly infiltrated by B lymphocytes but the relevance of these immune cells in tumor development has been surprisingly overlooked until recently. Based on available evidence from other solid tumors, interaction between B lymphocytes and neoplastic cells is probably not uniformly stimulatory or inhibitory. Although presentation of tumor antigens to T cells and production of antitumor immunoglobulins might intuitively suggest a prominent tumor suppressive activity, specific subsets of B lymphocytes can secrete growth factors for neoplastic cells and immunosuppressive cytokines thus promoting escape from immunosurveillance and cancer progression. Because many of these mechanisms might also be implicated in the development of PDAC, and immune-modulation of B-cell activity is nowadays possible at different levels, determining the role of B-lymphocytes in this lethal cancer becomes of utmost importance to design novel therapeutic strategies. This review aims to discuss the emerging role of B cells in PDAC tumorigenesis, progression, and associated stromal reaction.

The Glycolytic Pathway as a Target for Novel Onco-Immunology Therapies in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDA) is one of the most lethal forms of human cancer, characterized by unrestrained progression, invasiveness and treatment resistance. To date, there are limited curative options, with surgical resection as the only effective strategy, hence the urgent need to discover novel therapies. A platform of onco-immunology targets is represented by molecules that play a role in the reprogrammed cellular metabolism as one hallmark of cancer. Due to the hypoxic tumor microenvironment (TME), PDA cells display an altered glucose metabolism-resulting in its increased uptake-and a higher glycolytic rate, which leads to lactate accumulation and them acting as fuel for cancer cells. The consequent acidification of the TME results in immunosuppression, which impairs the antitumor immunity. This review analyzes the genetic background and the emerging glycolytic enzymes that are involved in tumor progression, development and metastasis, and how this represents feasible therapeutic targets to counteract PDA. In particular, as the overexpressed or mutated glycolytic enzymes stimulate both humoral and cellular immune responses, we will discuss their possible exploitation as immunological targets in anti-PDA therapeutic strategies.

Autoantibody-targeted TAAs in pancreatic cancer: A comprehensive analysis

BACKGROUND

Pancreatic cancer is one of the leading causes of cancer mortality and lacks efficient biomarkers for early diagnosis. In the early stages of pancreatic cancer, humoral immunity can respond to a certain amount of tumor-associated antigens (TAAs) with the production of corresponding autoantibodies. Such autoantibody-targeted TAAs (autoTAAs) are highly likely to indicate early events during pancreatic carcinogenesis. Herein, we performed a comprehensive analysis of these autoTAAs to explore their physiological function and their involvement and prognostic value in pancreatic cancer.

METHODS

We first searched the literature to identify the autoTAAs. A PPI network of these autoTAAs was constructed, and core network modules were extracted by Cytoscape software. GO annotation and KEGG pathway analysis were performed to analyze the main physiological functions of these autoTAAs. The prognostic value of autoTAAs in pancreatic cancer was analyzed by using RNA-seq data generated by TCGA.

RESULTS

The PPI network including 98 autoTAAs was constructed, and 2 subgroups were extracted as core modules. GO and KEGG analysis revealed that key functions and pathways of these autoTAAs were significantly enriched in nucleotide repair, protein synthesis, and cancer-associated events. MSH2, EZR, PGK1, VCL and ANXA2 have prognostic value in pancreatic cancer, and high mRNA expression of these 5 proteins is associated with unfavorable prognosis in pancreatic cancer.

CONCLUSIONS

AutoTAAs may be associated with early events in the carcinogenesis of pancreatic cancer. MSH2, EZR, PGK1, VCL and ANXA2 predict poor prognosis in pancreatic cancer. Some autoTAAs also have prognostic value in other cancers.

Integrative Analysis of Novel Metabolic Subtypes in Pancreatic Cancer Fosters New Prognostic Biomarkers

Background: Most of the patients with Pancreatic Ductal Adenocarcinoma (PDA) are not eligible for a curative surgical resection. For this reason there is an urgent need for personalized therapies. PDA is the result of complex interactions between tumor molecular profile and metabolites produced by its microenvironment. Despite recent studies identified PDA molecular subtypes, its metabolic classification is still lacking. Methods: We applied an integrative analysis on transcriptomic and genomic data of glycolytic genes in PDA. Data were collected from public datasets and molecular glycolytic subtypes were defined using hierarchical clustering. The grade of purity of the cancer samples was assessed estimating the different amount of stromal and immunological infiltrate among the identified PDA subtypes. Analyses of metabolomic data from a subset of PDA cell lines allowed us to identify the different metabolites produced by the metabolic subtypes. Sera of a cohort of 31 PDA patients were analyzed using Q-TOF mass spectrometer to measure the amount of metabolic circulating proteins present before and after chemotherapy. Results: Our integrative analysis of glycolytic genes identified two glycolytic and two non-glycolytic metabolic PDA subtypes. Glycolytic patients develop disease earlier, have poor prognosis, low immune-infiltrated tumors, and are characterized by a gain in chr12p13 genomic region. This gain results in the over-expression of GAPDH, TPI1, and FOXM1. PDA cell lines with the gain of chr12p13 are characterized by an higher lipid uptake and sensitivity to drug targeting the fatty acid metabolism. Our sera proteomic analysis confirms that TPI1 serum levels increase in poor prognosis gemcitabine-treated patients. Conclusions: We identify four metabolic PDA subtypes with different prognosis outcomes which may have pivotal role in setting personalized treatments. Moreover, our data suggest TPI1 as putative prognostic PDA biomarker.

No evidence of pancreatic ductal adenocarcinoma specific autoantibodies to Ezrin in a liquid phase LIPS immunoassay

BACKGROUND

Sensitive and specific biomarkers of Pancreatic Ductal Adenocarcinoma (PDAC) are desperately needed to allow early diagnosis and improve patient's survival. Ezrin autoantibodies were recently described as present in 93% of PDAC patients and 40% of healthy subjects who later developed PDAC. However, another prospective study failed to replicate these findings. Both studies were based on the use of a solid phase ELISA immunoassay.

OBJECTIVE

We aimed at re-evaluating the usefulness of Ezrin autoantibodies as PDAC biomarkers using the Luciferase Immuno Precipitation System (LIPS), an alternative immunoassay format that found successful application for the measurement of autoantibodies against pancreatic autoantigens.

METHODS

We produced a Nanoluciferase™ tagged Ezrin (NLuc-Ezrin). NLuc-Ezrin was then used as antigen in LIPS to test for Ezrin autoantibodies patients affected by PDAC (n= 40), other pancreatic diseases (OPD, n= 50), and healthy controls (n= 60).

RESULTS

Overall, binding in liquid phase to Ezrin by serum antibodies was rare and low titer. Furthermore, we did not find statistically significant differences in the prevalence of Ezrin autoantibodies between patients affected by either PDAC or OPD compared to control.

CONCLUSIONS

Our results do not confirm the usefulness of Ezrin autoAbs as biomarker of PDAC.

A systematic review of serum autoantibodies as biomarkers for pancreatic cancer detection

Pancreatic cancer is a leading cause of cancer-related deaths in the western world. Patients with pancreatic cancer have poor prognosis, partly due to difficulties in detecting it at early stages. While different markers have been associated with pancreatic cancer, many of them show suboptimal sensitivity and specificity. Serum autoantibodies against tumor-associated antigens have recently emerged as early stage biomarkers for different types of cancers. Given the urgent need for early and reliable biomarkers for pancreatic cancer, we undertook a systematic review of the published literature to identify primary articles that evaluated serum autoantibodies in pancreatic cancer detection by searching PubMed and ISI Web of Knowledge. Two reviewers extracted data on study characteristics and results independently. Overall, 31 studies evaluating 124 individual serum autoantibodies in pancreatic cancer detection met the inclusion criteria. In general, single autoantibody markers showed relatively low sensitivities at high specificity. A combination of markers, either multiple serum autoantibodies or serum autoantibodies combined with tumor-associated markers, led to a better diagnostic performance. However, most of the analyzed autoantibodies have only been reported in single studies and therefore need to be independently validated. We conclude that serum autoantibodies might present an option as biomarkers for early detection of pancreatic cancer, but more work is needed to identify and validate autoantibody signatures that are associated with early stage pancreatic cancer.

Glucose metabolic phenotype of pancreatic cancer

AIM: To construct a global “metabolic phenotype” of pancreatic ductal adenocarcinoma (PDAC) reflecting tumour-related metabolic enzyme expression.

METHODS: A systematic review of the literature was performed using OvidSP and PubMed databases using keywords “pancreatic cancer” and individual glycolytic and mitochondrial oxidative phosphorylation (MOP) enzymes. Both human and animal studies investigating the oncological effect of enzyme expression changes and inhibitors in both an in vitro and in vivo setting were included in the review. Data reporting changes in enzyme expression and the effects on PDAC cells, such as survival and metastatic potential, were extracted to construct a metabolic phenotype.

RESULTS: Seven hundred and ten papers were initially retrieved, and were screened to meet the review inclusion criteria. 107 unique articles were identified as reporting data involving glycolytic enzymes, and 28 articles involving MOP enzymes in PDAC. Data extraction followed a pre-defined protocol. There is consistent over-expression of glycolytic enzymes and lactate dehydrogenase in keeping with the Warburg effect to facilitate rapid adenosine-triphosphate production from glycolysis. Certain isoforms of these enzymes were over-expressed specifically in PDAC. Altering expression levels of HK, PGI, FBA, enolase, PK-M2 and LDA-A with metabolic inhibitors have shown a favourable effect on PDAC, thus identifying these as potential therapeutic targets. However, the Warburg effect on MOP enzymes is less clear, with different expression levels at different points in the Krebs cycle resulting in a fundamental change of metabolite levels, suggesting that other essential anabolic pathways are being stimulated.

CONCLUSION: Further characterisation of the PDAC metabolic phenotype is necessary as currently there are few clinical studies and no successful clinical trials targeting metabolic enzymes.

Profiling of autoantibodies in sera of pancreatic cancer patients

BACKGROUND

Although autoantibodies to cancer antigens are candidates for biomarkers, no comprehensive studies to detect cancer-specific antibodies have been performed. This study identified autoantibodies in the sera of pancreatic cancer (PC) patients using proteomics based on a wheat germ cell-free protein production system.

METHODS

We constructed a biotinylated protein library of 2,183 genes. Interactions between biotinylated proteins and serum antibodies were detected by AlphaScreen® assay. Relative luminescence signals of each protein in 37 PC patients and 20 healthy controls were measured, and their sensitivity and specificity for PC were calculated.

RESULTS

Luminescence signals of nine proteins were significantly higher than those of healthy controls, with calcium and integrin binding 1 (CIB1) protein showing the greatest significance (p = 0.002). Sensitivity, specificity, positive predictive value and negative predictive value of CIB1 autoantibody alone for PC were 76, 70, 82, and 61 %, respectively, and 97, 35, 74, and 88 %, respectively, when the four most significant proteins were combined. Presence of these autoantibodies did not vary significantly with other clinicopathological characteristics.

CONCLUSION

Several autoantibodies, including CIB1, are potential biomarkers for PC.

Serum autoantibodies to pancreatic cancer antigens as biomarkers of pancreatic cancer in a San Francisco Bay Area case-control study

BACKGROUND

Screening and early diagnosis tools are lacking for pancreatic adenocarcinoma; most patients are diagnosed with metastatic disease. Autoantibodies to tumor-associated antigens (TAAs) can be present months to years before diagnosis and hold promise as biomarkers for early detection.

METHODS

TAAs to pancreatic cancer autoantibodies CTDSP1 (carboxy-terminal domain, RNA polymerase II, polypeptide A, small phosphatase 1), MAPK9 (mitogen-activated protein kinase 9), and NR2E3 (nuclear receptor subfamily 2, group E, member 3), which were identified as potentially promising biomarkers in exploratory studies, were evaluated in serum from participants (300 cases, 300 controls) in a population-based case-control pancreatic cancer study in the San Francisco Bay Area. Patients were identified through cancer registry rapid case ascertainment, newly diagnosed from 1995 to 1999 and followed up through 2008. Autoantibody levels were analyzed as continuous and grouped (quartiles) variables. Multivariable unconditional logistic regression was used to compute odds ratios (ORs) as estimates of autoantibody levels associated with disease status. Kaplan-Meier product limit estimates and multivariable Cox proportional hazards regression were used to assess autoantibody levels associated with case survival duration.

RESULTS

Cases had higher levels of CTDSP1 (P = .004), MAPK9 (P = .0002), and NR2E3 (P ≤ .0001) autoantibodies than controls (fourth vs first quartile: CTDSP1 OR = 1.7, MAPK9 OR = 2.5, NR2E3 OR = 4.0). High body mass index and tobacco use were associated with levels in controls but were not statistical confounders. High CTDSP1 levels were somewhat associated with better survival (hazard ratio = 0.77, P = .07).

CONCLUSIONS

Combined with previous results, this study contributes evidence that cancer-related host immune-response factors may be useful diagnostic screening tools and prognostic indicators for pancreatic cancer. Further studies are needed to critically assess the value of autoantibody panels to TAAs in diagnostic screening, prognosis, and immunotherapy of pancreatic and other cancers.