Impact of Histotripsy on Development of Intrahepatic Metastases in a Rodent Liver Tumor Model

Histotripsy has been used for tumor ablation, through controlled, non-invasive acoustic cavitation. This is the first study to evaluate the impact of partial histotripsy ablation on immune infiltration, survival outcomes, and metastasis development, in an in vivo orthotopic, immunocompetent rat HCC model (McA-RH7777). At 7−9 days post-tumor inoculation, the tumor grew to 5−10 mm, and ~50−75% tumor volume was treated by ultrasound-guided histotripsy, by delivering 1−2 cycle histotripsy pulses at 100 Hz PRF (focal peak negative pressure P− >30 MPa), using a custom 1 MHz transducer. Complete local tumor regression was observed on MRI in 9/11 histotripsy-treated rats, with no local recurrence or metastasis up to the 12-week study end point, and only a <1 mm residual scar tissue observed on histology. In comparison, 100% of untreated control animals demonstrated local tumor progression, developed intrahepatic metastases, and were euthanized at 1−3 weeks. Survival outcomes in histotripsy-treated animals were significantly improved compared to controls (p-value < 0.0001). There was evidence of potentially epithelial-to-mesenchymal transition (EMT) in control tumor and tissue healing in histotripsy-treated tumors. At 2- and 7-days post-histotripsy, increased immune infiltration of CD11b+, CD8+ and NK cells was observed, as compared to controls, which may have contributed to the eventual regression of the untargeted tumor region in histotripsy-treated tumors.

Updates in the Diagnosis of Intraductal Neoplasms of the Pancreas

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest types of cancer worldwide. There are many reasons for this dismal prognosis, including the advanced stage at the time of diagnosis and the lack of effective therapeutic approaches. Intraductal papillary mucinous neoplasms (IPMNs) represent detectable and treatable precursor lesions of PDAC. Our understanding of the pathology of IPMNs has evolved over the past few decades, and new advances in diagnostic tools have emerged. The new World Health Organization (WHO) classification scheme now recognizes the previously considered variants of IPMNs, such as intraductal oncocytic papillary neoplasms (IOPNs) and intraductal tubulopapillary neoplasms (ITPNs), as distinct neoplasms. New imaging and molecular diagnostic tests are being developed to recognize these PDAC precursor lesions better. Here, we review the advances in diagnostic tools for IPMNs, IOPNs, and ITPNs, emphasizing the new (5th edition, 2019) WHO classification for pathological diagnosis, molecular markers, new laboratory tests, and imaging tools.

KDM6A Regulates Cell Plasticity and Pancreatic Cancer Progression by Noncanonical Activin Pathway

BACKGROUND & AIMS

Inactivating mutations of KDM6A, a histone demethylase, were frequently found in pancreatic ductal adenocarcinoma (PDAC). We investigated the role of KDM6A (lysine demethylase 6A) in PDAC development.

METHODS

We performed a pancreatic tissue microarray analysis of KDM6A protein levels. We used human PDAC cell lines for KDM6A knockout and knockdown experiments. We performed bromouridine sequencing analysis to elucidate the effects of KDM6A loss on global transcription. We performed studies with Ptf1a^Cre; LSL-Kras^G12D; Trp53^R172H/+; Kdm6a^{fl/fl or fl/Y}, Ptf1a^Cre; Kdm6a^{fl/fl or fl/Y}, and orthotopic xenograft mice to investigate the impacts of Kdm6a deficiency on pancreatic tumorigenesis and pancreatitis.

RESULTS

Loss of KDM6A was associated with metastasis in PDAC patients. Bromouridine sequencing analysis showed up-regulation of the epithelial-mesenchymal transition pathway in PDAC cells deficient in KDM6A. Loss of KDM6A promoted mesenchymal morphology, migration, and invasion in PDAC cells in vitro. Mechanistically, activin A and subsequent p38 activation likely mediated the role of KDM6A loss. Inhibiting either activin A or p38 reversed the effect. Pancreas-specific Kdm6a-knockout mice pancreata showed accelerated PDAC progression, developed a more aggressive undifferentiated type of PDAC, and increased metastases in the background of Kras and p53 mutations. Kdm6a-deficient pancreata in a pancreatitis model had a delayed recovery with increased PDAC precursor lesions compared with wild-type pancreata.

CONCLUSIONS

Loss of KDM6A accelerates PDAC progression and metastasis, most likely by a noncanonical p38-dependent activin A pathway. KDM6A also promotes pancreatic tissue recovery from pancreatitis. Activin A might be used as a therapeutic target for KDM6A-deficient PDACs.

Neutrophil in the Pancreatic Tumor Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is a malignancy with a poor prognosis and low survival rates. PDAC is characterized by a fibroinflammatory tumor microenvironment enriched by abundant fibroblasts and a variety of immune cells, contributing to its aggressiveness. Neutrophils are essential infiltrating immune cells in the PDAC microenvironment. Recent studies have identified several cellular mechanisms by which neutrophils are recruited to tumor lesion and promote tumorigenesis. This review summarizes the current understanding of the interplay between neutrophils, tumor cells, and other components in the PDAC tumor microenvironment. The prognosis and therapeutic implications of neutrophils in PDAC are also discussed.

Intraductal papillary neoplasm of the bile duct (IPNB): CT and MRI appearance with radiology-pathology correlation

PURPOSE

Intraductal papillary neoplasm of the bile duct (IPNB) is a precursor to invasive carcinoma and is a distinct pathologic diagnosis. The purpose of this study was to evaluate imaging features of IPNB on cross-sectional imaging studies with histopathologic correlation.

MATERIALS AND METHODS

In this IRB approved, HIPAA compliant retrospective observational analysis of 23 pathology proven IPNB tumors 22 imaging studies were reviewed, 14 CT and 8 MRI scans. Features evaluated in consensus by two subspecialty-trained abdominal radiologists included: presence of specific lesion/mass within the bile duct, location within the biliary tree, size, morphology, enhancement characteristics, and bile duct caliber.

RESULTS

Majority of the subjects (16/18, 90%) had definite intraluminal mass, of which 7 (39%) had a polypoid mass with upstream diffuse biliary ductal dilation and 5 (28%) had a plaque-like mass with focal stricture and upstream biliary ductal dilatation. 6/18 (33%) subjects had low grade dysplasia, most commonly intestinal subtype, 7/18 (39%) subjects presented with invasive component, commonly pancreaticobiliary subtype, and 5/18 (28%) presented with high grade dysplasia.

CONCLUSION

IPNB has increased predilection for extrahepatic bile ducts, commonly presenting as either an intraluminal polypoidal mass with associated upstream biliary ductal dilation or a focal plaque like mass with associated ductal stricture at the site of the tumor.

A Clinicopathologic and Molecular Update of Pancreatic Neuroendocrine Neoplasms With a Focus on the New World Health Organization Classification

CONTEXT.—

According to the 2017 World Health Organization classification, pancreatic neuroendocrine neoplasms (PanNENs) include a new category of pancreatic neuroendocrine tumor, grade 3, which is often difficult to differentiate from pancreatic neuroendocrine carcinoma. However, pancreatic neuroendocrine tumor grade 3 and pancreatic neuroendocrine carcinoma are distinct entities with very different clinical presentation, prognosis, and therapeutic strategies. Recent discoveries on the molecular characteristics of pancreatic neuroendocrine tumors also play an essential role in the pathologic differential diagnosis of PanNENs. In addition, the histopathologic varieties of PanNENs bring in many differential diagnoses with other pancreatic neoplasms, especially acinar cell carcinoma, solid pseudopapillary neoplasm, and ductal adenocarcinoma.

OBJECTIVE.—

To provide a brief update of the World Health Organization classification; the clinical, histopathologic, immunohistochemical, and molecular characteristics; and the differential diagnoses and biological behavior of PanNENs.

DATA SOURCES.—

Analysis of the pertinent literature (PubMed) and authors' clinical practice experience based on institutional and consultation materials.

CONCLUSIONS.—

The evolving clinical, histopathologic, immunohistochemical, and molecular features of PanNENs are reviewed. Important differential diagnoses with other neoplasms of the pancreas are discussed.

Expression and prognostic value of NSD1 and SETD2 in pancreatic ductal adenocarcinoma and its precursor lesions

Epigenetic regulation is emerging as a critical mechanism for pancreatic ductal adenocarcinoma (PDA) development. Histone methylation is an important regulatory mechanism, altering chromatin structure and promoter accessibility and causing aberrant gene expression. NSD1 and SETD2 genes encoding two histone H3K36 methyltransferases, are mutated or altered in 8-10% of PDA cases. However, whether there is altered protein expression of NSD1 or SETD2 in PDA and its precursors, and whether they have diagnostic or prognostic utility is unknown. Tissue microarrays composed of a total of 190 and 192 duplicated cases of PDA (n=74 and 75), metastatic PDA (n=17 and 18), pancreatic intraepithelial neoplasia (PanIN; n=19 and 24), intraductal papillary mucinous neoplasm (IPMN; n=36), mucinous cystic neoplasm (MCN; n=12) and benign pancreatic tissues (n=27 and 32) were analysed for expression of NSD1 and SETD2 by immunohistochemistry. We assessed intensity and percentage of positive cells. NSD1 expression was significantly increased in metastatic PDA compared to benign ducts, primary PDA, and all other lesions combined (p=0.03, 0.02, and 0.03 respectively). Additionally, significantly decreased SETD2 protein expression was found in metastatic PDA and PanIN lesions compared to benign ducts (p=0.04 and 0.007, respectively). High NSD1 expression was associated with clinical stage III/IV disease (p=0.026), tumour grade 2 (p=0.022), use of neoadjuvant therapy (p=0.037), and overall higher clinical stage (p=0.022). There is no significant difference in overall and progression-free survival between NSD1/SETD2 high and low PDA. Expression of NSD1 and SETD2 is specifically altered in metastatic PDA and some of the PDA precursor lesions, supporting their important role in PDA development and metastasis. In addition, increased NSD1 expression is significantly associated with higher clinical stage and neoadjuvant therapy, suggesting that NSD1 may be a useful prognostic marker.

Alterations of Epigenetic Regulators in Pancreatic Cancer and Their Clinical Implications

Pancreatic cancer is one of the most aggressive human cancer types with a five-year survival less than 7%. Emerging evidence revealed that many genetic alterations in pancreatic cancer target epigenetic regulators. Some of these mutations are driver mutations in cancer development. Several most important mechanisms of epigenetic regulations include DNA methylation, histone modifications (methylation, acetylation, and ubiquitination), chromatin remodeling, and non-coding ribonucleic acids (RNAs). These modifications can alter chromatin structure and promoter accessibility, and thus lead to aberrant gene expression. However, exactly how these alterations affect epigenetic reprogramming in pancreatic cancer cells and in different stages of tumor development is still not clear. This mini-review summarizes the current knowledge of epigenetic alterations in pancreatic cancer development and progression, and discusses the clinical applications of epigenetic regulators as diagnostic biomarkers and therapeutic targets in pancreatic cancer.

Intraductal Tubulopapillary Neoplasm of the Pancreas: An Update From a Pathologist's Perspective

Context.—Intraductal tubulopapillary neoplasm (ITPN) is a rare intraductal epithelial neoplasm of the pancreas recently recognized as a distinct entity by the World Health Organization classification in 2010. It is defined as an intraductal, grossly visible, tubule-forming epithelial neoplasm with high-grade dysplasia and ductal differentiation without overt production of mucin. The diagnosis can be challenging owing to morphologic overlap with other intraductal lesions and its rarity. While recent advances in molecular genetic studies of ITPN have provided new tools to facilitate clinical diagnosis, the limited number of cases has yielded limited follow-up data to guide management.

Objective.—To provide a clinical, pathologic, and molecular update on ITPN with respect to clinical presentation, imaging findings, histopathologic features, differential diagnosis, biological behavior, molecular characteristics, and treatment options.

Data Sources.—Analysis of the pertinent literature (PubMed) and authors' research and clinical practice experience based on institutional and consultation materials.

Conclusions.—Clinical presentation, imaging findings, histopathology, immunohistochemistry studies, molecular characteristics, prognosis, and treatment options of ITPN are reviewed. Important differential diagnoses with other intraductal neoplasms of the pancreas—especially intraductal papillary mucinous neoplasm—using histopathologic, molecular, and immunohistochemical studies, are discussed. Despite the recent progress, more studies are necessary to assess the biology and genetics of ITPN for a better understanding of the prognostic factors and treatment options.

Extracellular DNA in pancreatic cancer promotes cell invasion and metastasis

Aggressive metastasis is the chief cause of the high morbidity and mortality associated with pancreatic cancer, yet the basis for its aggressive behavior remains elusive. Extracellular DNA (exDNA) is a recently discovered component of inflammatory tissue states. Here, we report that exDNA is present on the surface of pancreatic cancer cells where it is critical for driving metastatic behavior. exDNA was abundant on the surface and vicinity of cultured pancreatic cancer cells but absent from normal pancreas cells. Strikingly, treatment of cancer cell cultures with DNase I to degrade DNA nonspecifically reduced metastatic characters associated with matrix attachment, migration, and invasion. We further assessed the role of exDNA in pancreatic cancer metastasis in vivo using an orthotopic xenograft model established by implantation of pancreatic cancer cells expressing firefly luciferase. Noninvasive bioluminescent imaging confirmed that DNase I treatment was sufficient to suppress tumor metastasis. Mechanistic investigations suggested the existence of a positive feedback loop in which exDNA promotes expression of the inflammatory chemokine CXCL8, which leads to higher production of exDNA by pancreatic cancer cells, with a significant reduction in CXCL8 levels achieved by DNase I treatment. Taken together, our results strongly suggest that exDNA contributes to the highly invasive and metastatic character of pancreatic cancer.