Impact of somatic mutations on clinical and pathologic outcomes in borderline resectable and locally advanced pancreatic cancer treated with neoadjuvant chemotherapy and stereotactic body radiotherapy followed by surgical resection

PURPOSE

The purpose of this study was to determine if somatic mutations are associated with clinical and pathologic outcomes in patients with borderline resectable pancreatic cancer (BRPC) or locally advanced pancreatic cancer (LAPC) who were treated with neoadjuvant chemotherapy and stereotactic body radiotherapy (SBRT).

MATERIALS AND METHODS

Patients treated with neoadjuvant chemotherapy and SBRT followed by surgical resection from August 2016 to January 2019 and who underwent next generation sequencing of their primary tumor were included in the study. Next-generation sequencing was performed either in-house with a Solid Tumor Panel or with FoundationOne CDx. Univariate (UVA) and multivariable analyses (MVA) were performed to determine associations between somatic mutations and pathologic and clinical outcomes.

RESULTS

Thirty-five patients were included in the study. Chemotherapy consisted of modified FOLFIRINOX, gemcitabine and nab-paclitaxel, or gemcitabine and capecitabine. Patients were treated with SBRT in 33 Gy in 5 fractions. On UVA and MVA, tumors with KRAS G12V mutation demonstrated better pathologic tumor regression grade (TRG) to neoadjuvant therapy when compared to tumors with other KRAS mutations (odds ratio = 0.087; 95% confidence interval [CI], 0.009-0.860; p = 0.036). On UVA and MVA, mutations in NOTCH1/2 were associated with worse overall survival (hazard ratio [HR] = 4.15; 95% CI, 1.57-10.95; p = 0.004) and progression-free survival (HR = 3.61; 95% CI, 1.41-9.28; p = 0.008). On UVA, only mutations in NOTCH1/2 were associated with inferior distant metastasis-free survival (HR = 3.38; 95% CI, 1.25-9.16; p = 0.017).

CONCLUSION

In BRPC and LAPC, the KRAS G12V mutation was associated with better TRG following chemotherapy and SBRT. Additionally, NOTCH1/2 mutations were associated with worse overall survival, distant metastasis-free survival, and progression-free survival.

PIM-induced phosphorylation of Notch3 promotes breast cancer tumorigenicity in a CSL-independent fashion

Dysregulation of the developmentally important Notch signaling pathway is implicated in several types of cancer, including breast cancer. However, the specific roles and regulation of the four different Notch receptors have remained elusive. We have previously reported that the oncogenic PIM kinases phosphorylate Notch1 and Notch3. Phosphorylation of Notch1 within the second nuclear localization sequence of its intracellular domain (ICD) enhances its transcriptional activity and tumorigenicity. In this study, we analyzed Notch3 phosphorylation and its functional impact. Unexpectedly, we observed that the PIM target sites are not conserved between Notch1 and Notch3. Notch3 ICD (N3ICD) is phosphorylated within a domain, which is essential for formation of a transcriptionally active complex with the DNA-binding protein CSL. Through molecular modeling, X-ray crystallography, and isothermal titration calorimetry, we demonstrate that phosphorylation of N3ICD sterically hinders its interaction with CSL and thereby inhibits its CSL-dependent transcriptional activity. Surprisingly however, phosphorylated N3ICD still maintains tumorigenic potential in breast cancer cells under estrogenic conditions, which support PIM expression. Taken together, our data indicate that PIM kinases modulate the signaling output of different Notch paralogs by targeting distinct protein domains and thereby promote breast cancer tumorigenesis via both CSL-dependent and CSL-independent mechanisms.

Pathological Conversion of Mouse Perivascular Adipose Tissue by Notch Activation

OBJECTIVE

Perivascular adipose tissue (PVAT) surrounding arteries supports healthy vascular function. During obesity, PVAT loses its vasoprotective effect. We study pathological conversion of PVAT, which involves molecular changes in protein profiles and functional changes in adipocytes. Approach and Results: C57BL6/J mice were fed a 60% high-fat diet for 12 weeks or a cardioprotective 30% calorie-restricted diet for 5 weeks. Proteomic analysis identified PVAT as a molecularly distinct adipose depot, and novel markers for thermogenic adipocytes, such as GRP75 (stress-70 protein, mitochondrial), were identified. High-fat diet increased the similarity of protein signatures in PVAT and brown adipose, suggesting activation of a conserved whitening pathway. The whitening phenotype was characterized by suppression of UCP1 (uncoupling protein 1) and increased lipid deposition, leptin, and inflammation, and specifically in PVAT, elevated Notch signaling. Conversely, PVAT from calorie-restricted mice had decreased Notch signaling and less lipid. Using the Adipoq-Cre strain, we constitutively activated Notch1 signaling in adipocytes, which phenocopied the changes in PVAT caused by a high-fat diet, even on a standard diet. Preadipocytes from mouse PVAT expressed Sca1, CD140a, Notch1, and Notch2, but not CD105, showing differences compared with preadipocytes from other depots. Inhibition of Notch signaling during differentiation of PVAT-derived preadipocytes reduced lipid deposition and adipocyte marker expression.

CONCLUSIONS

PVAT shares features with other adipose depots, but has a unique protein signature that is regulated by dietary stress. Increased Notch signaling in PVAT is sufficient to initiate the pathological conversion of PVAT by promoting adipogenesis and lipid accumulation and may thus prime the microenvironment for vascular disease.

Therapeutic Targeting of the Notch Pathway in Glioblastoma Multiforme

BACKGROUND

Glioblastoma (GBM) is the most common and deadly form of brain tumor. After standard treatment of resection, radiotherapy, and chemotherapy, the 5-year survival is <5%. In recent years, research has uncovered several potential targets within the Notch signaling pathway, which may lead to improved patient outcomes.

METHODS

A literature search was performed for articles containing the terms "Glioblastoma" and "Receptors, Notch" between 2003 and July 2015. Of the 62 articles retrieved, 46 met our criteria and were included in our review. Nine articles were identified from other sources and were subsequently included, leaving 55 articles reviewed.

RESULTS

Of the 55 articles reviewed, 47 used established human GBM cell lines. Seventeen articles used human GBM surgical samples. Forty-five of 48 articles that assessed Notch activity showed increased expression in GBM cell lines. Targeting the Notch pathway was carried out through Notch knockdown and overexpression and targeting δ-like ligand, Jagged, γ-secretase, ADAM10, ADAM17, and Mastermindlike protein 1. Arsenic trioxide, microRNAs, and several other compounds were shown to have an effect on the Notch pathway in GBM. Notch activity in GBM was also shown to be associated with hypoxia and certain cancer-related molecular pathways such as PI3K/AKT/mTOR and ERK/MAPK. Most articles concluded that Notch activity amplifies malignant characteristics in GBM and targeting this pathway can bring about amelioration of these effects.

CONCLUSIONS

Recent literature suggests targeting the Notch pathway has great potential for future therapies for GBM.

Endothelial Jagged1 antagonizes Dll4 regulation of endothelial branching and promotes vascular maturation downstream of Dll4/Notch1

OBJECTIVE

Notch signaling controls cardiovascular development and has been associated with several pathological conditions. Among its ligands, Jagged1 and Dll4 were shown to have opposing effects in developmental angiogenesis, but the underlying mechanism and the role of Jagged1/Notch signaling in adult angiogenesis remain incompletely understood. The current study addresses the importance of endothelial Jagged1-mediated Notch signaling in the context of adult physiological angiogenesis and the interactions of Jagged1 and Dll4 on angiogenic response and vascular maturation processes.

APPROACH AND RESULTS

The role of endothelial Jagged1 in wound healing kinetics and angiogenesis was investigated with endothelial-specific Jag1 gain-of-function and loss-of-function mouse mutants (eJag1OE and eJag1cKO). To study the interactions between the 2 Notch ligands, genetic mouse models were combined with pharmacological inhibition of Dll4 or Jagged1, respectively. Jagged1 overexpression in endothelial cells increased vessel density, maturation, and perfusion, thus accelerating wound healing. The opposite effect was seen in eJag1cKO animals. Interestingly, Dll4 blockade in these animals led to an increase in vascular density but induced a greater decrease in perivascular cell coverage. However, Jagged1 inhibition in Dll4 gain-of-function (eDll4OE) mutants, with reduced angiogenesis, further diminished angiogenic growth and hampered perivascular cell coverage. Our findings suggest that as Dll4 blocks endothelial activation through Notch1 signaling, it also induces Jagged1 expression. Jagged1 then blocks Dll4 signaling through Notch1, allowing endothelial activation by vascular endothelial growth factor and endothelial layer growth. Jagged1 also initiates maturation of the newly formed vessels, possibly by binding and activating endothelial Notch4. Importantly, mice administered with a Notch4 agonistic antibody mimicked the mural cell phenotype of eJag1OE mutants without affecting angiogenic growth, which is thought to be Notch1 dependent.

CONCLUSIONS

Endothelial Jagged1 is likely to operate downstream of Dll4/Notch1 signaling to activate Notch4 and regulate vascular maturation. Thus, Jagged1 not only counteracts Dll4/Notch in the endothelium but also generates a balance between angiogenic growth and maturation processes in vivo.

Expression of notch family proteins in placentas from patients with early-onset severe preeclampsia

OBJECTIVES

This study is aimed to identify the expression of Notch family proteins in placentas from patients with early-onset severe preeclampsia.

STUDY DESIGN

The expression of Notch family proteins in placentas was investigated by immunohistochemistry, Western blotting, and real-time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The profile of distribution of all Notch family proteins in placentas from patients with early-onset severe preeclampsia is similar to that in normal placentas. All Notch family proteins are expressed in placental trophoblasts. Moreover, Notch1 and Jagged1 (Jag1) are detected in placental endothelial cells. Real-time RT-PCR showed that messenger RNA levels of Notch2 and Delta-like4 (Dll4) in placentas from patients with early-onset severe preeclampsia are lower than that of normal placentas. Western blotting showed a significant increase in Notch3 expression and a significant decrease in Notch2 expression in placentas from patients with early-onset severe preeclampsia relative to those in normal placentas.

CONCLUSION

The results suggest that Notch2 and Notch3 may play some roles in the pathogenesis of preeclampsia.