Background
Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is categorized into four distinct types: the gastric, intestinal, pancreatobiliary, and oncocytic. Each type is associated ...with specific clinicopathological features. We aimed to uncover the molecular mechanisms underlying the development of these types of IPMN.
Methods
We obtained 103 lesions of various types, including 49 gastric, 26 intestinal, 22 pancreatobiliary, and 6 oncocytic lesions, from 43 IPMNs, including 36 with multiple types. Comparative analysis was performed by targeted sequencing of 37 genes in different lesion types within each pancreas.
Results
Gastric-type low-grade lesions were observed in all 36 tumors with multiple types, with 245 mutations identified across all samples. The average number of mutations was significantly different between different lesion grades and types: 1.88 for low-grade lesions, 2.77 for high-grade lesions, and 2.38 for invasive lesions (
p
= 0.0067); and 1.96 for gastric-type lesion, 2.92 for intestinal-type lesion, 2.73 for pancreatobiliary-type lesion, and 2.17 for oncocytic-type lesion (
p
= 0.0163). Tracing of mutations between lesions containing multiple types in the same pancreas suggested three developmental pathways, denoted as “progressive”, “divergent”, and “independent”. The progressive and divergent pathways indicate an ancestral lesion that was mostly gastric-type and low-grade may progress or diversify into lesions of other types and/or higher grades. The independent pathway suggests that some high-grade lesions of any type may develop independently.
Conclusion
These findings suggest that gastric-type low-grade lesions have a risk of progression into high-grade lesions of other types. Therefore, low-grade gastric-type IPMNs should be under constant surveillance.
Background
Cell-free DNA (cfDNA) shed from tumors into the circulation offers a tool for cancer detection. Here, we evaluated the feasibility of cfDNA measurement and utility of digital PCR ...(dPCR)-based assays, which reduce subsampling error, for diagnosing pancreatic ductal adenocarcinoma (PDA) and surveillance of intraductal papillary mucinous neoplasm (IPMN).
Methods
We collected plasma from seven institutions for cfDNA measurements. Hot-spot mutations in
KRAS
and
GNAS
in the cfDNA from patients with PDA (
n
= 96), undergoing surveillance for IPMN (
n
= 112), and normal controls (
n
= 76) were evaluated using pre-amplification dPCR.
Results
Upon Qubit measurement and copy number assessment of hemoglobin-subunit (
HBB
) and mitochondrially encoded NADH:ubiquinone oxidoreductase core subunit 1 (
MT-ND1
) in plasma cfDNA,
HBB
offered the best resolution between patients with PDA relative to healthy subjects area under the curve (AUC) 0.862, whereas
MT-ND1
revealed significant differences between IPMN and controls (AUC 0.851). DPCR utilizing pre-amplification cfDNA afforded accurate tumor-derived mutant
KRAS
detection in plasma in resectable PDA (AUC 0.861–0.876) and improved post-resection recurrence prediction hazard ratio (HR) 3.179, 95% confidence interval (CI) 1.025–9.859 over that for the marker CA19-9 (HR 1.464; 95% CI 0.674–3.181). Capturing
KRAS
and
GNAS
could also provide genetic evidence in patients with IPMN-associated PDA and undergoing pancreatic surveillance.
Conclusions
Plasma cfDNA quantification by distinct measurements is useful to predict tumor burden. Through appropriate methods, dPCR-mediated mutation detection in patients with localized PDA and IPMN likely to progress to invasive carcinoma is feasible and complements conventional biomarkers.
Pancreatic cancer currently has no subtypes that inform clinical decisions; hence, there exists an opportunity to rearrange the morphological and molecular taxonomy that guides a better understanding ...of tumor characteristics. Nonetheless, accumulating studies to date have revealed the large-duct type variant, a unique subtype of pancreatic ductal adenocarcinoma (PDA) with cystic features. This subtype often radiographically mimics intraductal papillary mucinous neoplasms (IPMNs) and involves multiple small cysts occasionally associated with solid masses. The “bunch-of-grapes” sign, an imaging characteristic of IPMNs, is absent in large-duct PDA. Large-duct PDA defines the mucin profile, and genetic alterations are useful in distinguishing large-duct PDA from IPMNs. Histologically, neoplastic ducts measure over 0.5 mm, forming large ductal elements. Similar to classic PDAs, this subtype is frequently accompanied by perineural invasion and abundant desmoplastic reactions, and
KRAS
mutations in codon 12 are nearly ubiquitous. Despite such morphological similarities with IPMNs, the prognosis of large-duct PDA is equivalent to that of classic PDA. Differential diagnosis is therefore essential.
Intraductal papillary mucinous neoplasms (IPMNs) are regarded as precursors of pancreatic ductal adenocarcinomas (PDAs), but little is known about the mechanism of progression. This makes it ...challenging to assess cancer risk in patients with IPMNs. We investigated associations of IPMNs with concurrent PDAs by genetic and histologic analyses.
We obtained 30 pancreatic tissues with concurrent PDAs and IPMNs, and 168 lesions, including incipient foci, were mapped, microdissected, and analyzed for mutations in 18 pancreatic cancer-associated genes and expression of tumor suppressors.
We determined the clonal relatedness of lesions, based on driver mutations shared by PDAs and concurrent IPMNs, and classified the lesions into 3 subtypes. Twelve PDAs contained driver mutations shared by all concurrent IPMNs, which we called the sequential subtype. This subset was characterized by less diversity in incipient foci with frequent GNAS mutations. Eleven PDAs contained some driver mutations that were shared with concurrent IPMNs, which we called the branch-off subtype. In this subtype, PDAs and IPMNs had identical KRAS mutations but different GNAS mutations, although the lesions were adjacent. Whole-exome sequencing and methylation analysis of these lesions indicated clonal origin with later divergence. Ten PDAs had driver mutations not found in concurrent IPMNs, called the de novo subtype. Expression profiles of TP53 and SMAD4 increased our ability to differentiate these subtypes compared with sequencing data alone. The branch-off and de novo subtypes had substantial heterogeneity among early clones, such as differences in KRAS mutations. Patients with PDAs of the branch-off subtype had a longer times of disease-free survival than patients with PDAs of the de novo or the sequential subtypes.
Detailed histologic and genetic analysis of PDAs and concurrent IPMNs identified 3 different pathways by which IPMNs progress to PDAs—we call these the sequential, branch-off, and de novo subtypes. Subtypes might be associated with clinical and pathologic features and be used to select surveillance programs for patients with IPMNs.
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Pancreatic cancer is associated with an extremely poor prognosis, so new biomarkers that can detect the initial stages are urgently needed. The significance of serum microRNA (miR) levels in ...pancreatic neoplasm such as pancreatic cancer and intraductal papillary mucinous neoplasm (IPMN) diagnosis remains unclear. We herein evaluated the usefulness of miRs enclosed in serum exosomes (ExmiRs) as diagnostic markers.
The ExmiRs from patients with pancreatic cancer (n = 32) or IPMN (n = 29), and patients without neoplasms (controls; n = 22) were enriched using ExoQuick-TC™. The expression of ExmiRs was evaluated using a next-generation sequencing analysis, and the selected three miRs through this analysis were confirmed by a quantitative real-time polymerase chain reaction.
The expression of ExmiR-191, ExmiR-21 and ExmiR-451a was significantly up-regulated in patients with pancreatic cancer and IPMN compared to the controls (p < 0.05). A receiver operating characteristic curve analysis showed that the area under the curve and the diagnostic accuracy of ExmiRs were 5-20% superior to those of three serum bulky circulating miRs (e.g.; ExmiR-21: AUC 0.826, accuracy 80.8%. Circulating miR-21: AUC 0.653, accuracy 62.3%). In addition, high ExmiR-451a was associated with mural nodules in IPMN (p = 0.010), and high ExmiR-21 was identified as a candidate prognostic factor for the overall survival (p = 0.011, HR 4.071, median OS of high-ExmiR-21: 344 days, median OS of low-ExmiR-21: 846 days) and chemo-resistant markers (p = 0.022).
The level of three ExmiRs can thus serve as early diagnostic and progression markers of pancreatic cancer and IPMN, and considered more useful markers than the circulating miRs (limited to these three miRs).
Background
We previously showed that
Lactobacillus brevis
-derived polyphosphate (poly P) exerts a curative effect on intestinal inflammation. However, whether or not poly P improves the inflammation ...and injury of distant organs remains unclear.
Aims
We aimed to investigate the change in the intestinal microbiome and to evaluate the protective effect of poly P on injuries in a cerulein-induced acute pancreatitis (AP) mouse.
Methods
Poly P was orally administered to BALB/C mice every day for 24 days, and then mice were intraperitoneally injected with cerulein. Before cerulein injection, stool samples were collected and analyzed by 16S rRNA gene sequencing. Mice were sacrificed at 24 h after the last cerulein injection; subsequently, the serum, pancreas, and colon were collected.
Results
The microbial profile differed markedly between poly P and control group. Notably, the levels of beneficial bacteria, including
Alistipes
and
Candidatus_Saccharimonas
, were significantly increased, while those of the virulent bacteria
Desulfovibrio
were decreased in the poly P group. The elevations of the serum amylase and lipase levels by cerulein treatment were suppressed by the pre-administration of poly P for 24 days, but not for 7 days. The numbers of cells MPO-positive by immunohistology were decreased and the levels of MCP-1 significantly reduced in the AP + Poly P group. An immunofluorescence analysis showed that the ZO-1 and occludin in the colon was strongly augmented in the epithelial cell membrane layer in the AP + Poly P group.
Conclusions
Poly P attenuates AP through both modification of the intestinal microbiome and enhancement of the intestinal barrier integrity.
The two principal histological types of primary liver cancers, hepatocellular carcinoma (HCC) and cholangiocarcinoma, can coexist within a tumor, comprising combined hepatocellular‐cholangiocarcinoma ...(cHCC‐CCA). Although the possible involvement of liver stem/progenitor cells has been proposed for the pathogenesis of cHCC‐CCA, the cells might originate from transformed hepatocytes that undergo ductular transdifferentiation or dedifferentiation. We previously demonstrated that concomitant introduction of mutant HRASV12 (HRAS) and Myc into mouse hepatocytes induced dedifferentiated tumors that expressed fetal/neonatal liver genes and proteins. Here, we examine whether the phenotype of HRAS‐ or HRAS/Myc‐induced tumors might be affected by the disruption of the Trp53 gene, which has been shown to induce biliary differentiation in mouse liver tumors. Hepatocyte‐derived liver tumors were induced in heterozygous and homozygous p53‐knockout (KO) mice by hydrodynamic tail vein injection of HRAS‐ or Myc‐containing transposon cassette plasmids, which were modified by deleting loxP sites, with a transposase‐expressing plasmid. The HRAS‐induced and HRAS/Myc‐induced tumors in the wild‐type mice demonstrated histological features of HCC, whereas the phenotype of the tumors generated in the p53‐KO mice was consistent with cHCC‐CCA. The expression of fetal/neonatal liver proteins, including delta‐like 1, was detected in the HRAS/Myc‐induced but not in the HRAS‐induced cHCC‐CCA tissues. The dedifferentiation in the HRAS/Myc‐induced tumors was more marked in the homozygous p53‐KO mice than in the heterozygous p53‐KO mice and was associated with activation of Myc and YAP and suppression of ERK phosphorylation. Our results suggest that the loss of p53 promotes ductular differentiation of hepatocyte‐derived tumor cells through either transdifferentiation or Myc‐mediated dedifferentiation.
The loss of p53 promotes ductular differentiation of hepatocyte‐derived tumor cells through either transdifferentiation or Myc‐mediated dedifferentiation. This figure shows a two‐dimensional perspective of the hepatocyte‐derived tumors with respect to transdifferentiation and dedifferentiation.
Tumor‐derived signals systemically induce an angiogenic switch that allows cancer cells to survive and grow. However, the vascular network in tumors is not well organized and fails to meet metabolic ...needs to maintain tissue homeostasis, resulting in significant hypoxia. Among various tumors, pancreatic ductal adenocarcinoma (PDAC) typically develops in an unusually disordered microenvironment, which contributes to its highly aggressive behavior. Since anti‐vascular endothelial growth factor (VEGF) (Avastin) has failed to demonstrate a survival benefit in PDAC, we need to re‐visit the basic biology of this disease and understand what makes it so refractory to the anti‐angiogenic approaches that are clinically effective in other neoplasms. To address this issue, we specifically focused on the process of neovascularization where bone marrow‐derived cells (BMDCs) play a role during pancreatic tumorigenesis. We have identified subsets of BMDCs that regulate key processes during development of the neovessels through paracrine Hedgehog signaling. Considering the importance of systemic responses occurring in tumor bearing hosts, we are currently using genetically engineered mice, which spontaneously develop PDAC, Pdx1‐Cre;LSL‐KrasG12D;p53lox/+ strain, to clarify critical events that can trigger aberrant angiogenesis in pancreatic cancer. These studies allow us to provide insights into the cellular and molecular mechanisms of pancreatic tumorigenesis and have an implication for the design of therapies against this difficult disease.
We aimed to elucidate the clinicopathobiological significance of Serine/Threonine Kinase 11 (STK11) in pancreatic intraductal papillary mucinous neoplasms (IPMNs).
STK11 is a tumor suppressor ...involved in certain IPMNs; however, its significance is not well known.
In 184 IPMNs without Peutz-Jeghers syndrome, we analyzed expression of STK11 and phosphorylated-AMPKa in all cases, and p16, p53, SMAD4, and β-catenin in 140 cases by immunohistochemistry; and we analyzed mutations in 37 genes, including whole coding exons of STK11, CDKN2A, TP53, and SMAD4, and hotspots of KRAS, BRAF, and GNAS in 64 cases by targeted sequencing. KRAS and GNAS were additionally analyzed in 86 STK11-normal IPMNs using digital-PCR.
Consistent loss or reduction of STK11 expression was observed in 26 of 184 (14%) IPMNs. These STK11-aberrant IPMNs were 17 of 45 (38%) pancreatobiliary, 8 of 27 (30%) oncocytic, 1 of 54 (2%) gastric, and 0 of 58 (0%) intestinal subtypes ( P = 8.5E-11), and 20 of 66 (30%) invasive, 6 of 74 (8%) high-grade, and 0 of 44 (0%) low-grade ( P = 3.9E-06). Sixteen somatic STK11 mutations (5 frameshift, 6 nonsense, 1 splicing, and 4 missense) were detected in 15/26 STK11-aberrant IPMNs ( P = 4.1E-06). All STK11-aberrantIPMNs were GNAS -wild-type and 96% of them were KRAS or BRAF -mutant.Morphologically, STK11-aberrant IPMNs presented "fern-like" arborizing papillae with thin fibrovascular core. Phosphorylated-AMPKa was down-regulated in STK11-aberrant IPMNs (92%, P = 6.8E-11). Patients with STK11-aberrant IPMNs showed poorer survival than patients with STK11-normal IPMNs ( P = 3.6E-04 overall; P = 6.1E-04 disease-free).
STK11 may play a canonical role in malignant progression and poor survival of patients with IPMNs. Aberrant STK11-driven phosphorylated AMPK downregulation may provide therapeutic opportunities with mTOR inhibitors/AMPK activators.
Pancreatic ductal adenocarcinoma (PDA), one of the most lethal cancers worldwide, is associated with two main types of morphologically distinct precursors-pancreatic intraepithelial neoplasia (PanIN) ...and intraductal papillary mucinous neoplasm (IPMN). Although the progression of PanIN into invasive cancer has been well characterized, there remains an urgent need to understand the biology of IPMNs, which are larger radiographically detectable cystic tumors. IPMNs comprise a number of subtypes with heterogeneous histopathologic and clinical features. Although frequently remaining benign, a significant proportion exhibits malignant progression. Unfortunately, there are presently no accurate prognosticators for assessing cancer risk in individuals with IPMN. Moreover, the fundamental mechanisms differentiating PanIN and IPMN remain largely obscure, as do those that distinguish IPMN subtypes. Recent studies, however, have identified distinct genetic profiles between PanIN and IPMN, providing a framework to better understand the diversity of the precursors for PDA. Here, we review the clinical, biological, and genetic properties of IPMN and discuss various models for progression of these tumors to invasive PDA.
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