We studied the effects of gut microbiome depletion by oral antibiotics on tumor growth in subcutaneous and liver metastases models of pancreatic cancer, colon cancer, and melanoma. Gut microbiome ...depletion significantly reduced tumor burden in all the models tested. However, depletion of gut microbiome did not reduce tumor growth in Rag1-knockout mice, which lack mature T and B cells. Flow cytometry analyses demonstrated that gut microbiome depletion led to significant increase in interferon gamma–producing T cells with corresponding decrease in interleukin 17A and interleukin 10–producing T cells. Our results suggest that gut microbiome modulation could emerge as a novel immunotherapeutic strategy.
Pancreatic ductal adenocarcinoma (PDAC) is considered to be a highly immunosuppressive and heterogenous neoplasm. Despite improved knowledge regarding the genetic background of the tumor and better ...understanding of the tumor microenvironment, immune checkpoint inhibitor therapy (targeting CTLA4, PD1, PDL1) has not been very successful against PDAC. The robust desmoplastic stroma, along with an extensive extracellular matrix (ECM) that is rich in hyaluronan, plays an integral role in this immune evasion. Hexosamine biosynthesis pathway (HBP), a shunt pathway of glycolysis, is a metabolic node in cancer cells that can promote survival pathways on the one hand and influence the hyaluronan synthesis in the ECM on the other. The rate-limiting enzyme of the pathway, glutamine-fructose amidotransferase 1 (GFAT1), uses glutamine and fructose 6-phosphate to eventually synthesize uridine diphosphate N-acetylglucosamine (UDP-GlcNAc). In the current manuscript, we targeted this glutamine-utilizing enzyme by a small molecule glutamine analog (6-diazo-5-oxo-l-norleucine DON). Our results showed that DON decreased the self-renewal potential and metastatic ability of tumor cells. Further, treatment with DON decreased hyaluronan and collagen in the tumor microenvironment, leading to an extensive remodeling of the ECM and an increased infiltration of CD8+ T cells. Additionally, treatment with DON sensitized pancreatic tumors to anti-PD1 therapy, resulting in tumor regression and prolonged survival.
There is an urgent need for novel and effective treatment options for acute myeloid leukemia (AML). Triptolide, a diterpenoid tri-epoxide compound isolated from the herb Tripterygium wilfordii and ...its water-soluble pro-drug-Minnelide have shown promising anti-cancer activity. A recent clinical trial for patients with solid tumors confirmed the safety and efficacy at biologically equivalent doses of 0.2 mg/kg/day and lower.
Cell viability of multiple AML cell lines as well as patient apheresis samples were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) based assay. Apoptosis was evaluated by estimating the amount of cleaved caspase. AML cell line (THP1-Luc) was implanted in immunocompromised mice and treated with indicated doses of Minnelide. Leukemic burden before and after treatment was evaluated by imaging in an In Vivo Imaging System (IVIS).
In the current study, we show that Minnelide, at doses below maximum tolerated dose (MTD) demonstrates leukemic clearance of both primary AML blasts and luciferase expressing THP-1 cells in mice. In vitro, multiple primary AML apheresis samples and AML cell lines (THP-1, KG1, Kasumi-1, HL-60) were sensitive to triptolide mediated cell death and apoptosis in low doses. Treatment with triptolide led to a significant decrease in the colony forming ability of AML cell lines as well as in the expression of stem cell markers. Additionally, it resulted in the cell cycle arrest in the G1/S phase with significant downregulation of c-Myc, a major transcriptional regulator mediating cancer cell growth and stemness.
Our results suggest that Minnelide, with confirmed safety and activity in the clinic, exerts a potent anti-leukemic effect in multiple models of AML at doses easily achievable in patients.
Gastric cancer is the third leading cause of cancer related mortality worldwide with poor survival rates. Even though a number of chemotherapeutic compounds have been used against this disease, ...stomach cancer has not been particularly sensitive to these drugs. In this study we have evaluated the effect of triptolide, a naturally derived diterpene triepoxide and its water soluble pro-drug Minnelide on several gastric adenocarcinoma cell lines both as monotherapy and in combination with CPT-11.
Gastric cancer cell lines MKN28 and MKN45 were treated with varying doses of triptolide in vitro. Cell viability was measured using MTT based assay kit. Apoptotic cell death was assayed by measuring caspase activity. Effect of the triptolide pro-drug, Minnelide, was evaluated by implanting the gastric cancer cells subcutaneously in athymic nude mice.
Gastric cancer cell lines MKN28 and MKN45 cells exhibited decreased cell viability and increased apoptosis when treated with varying doses of triptolide in vitro. When implanted in athymic nude mice, treatment with Minnelide reduced tumor burden in both MKN28 derived tumors as well as MKN45 derived tumors. Additionally, we also evaluated Minnelide as a single agent and in combination with CPT-11 in the NCI-N87 human gastric tumor xenograft model.
Our results indicated that the combination of Minnelide with CPT-11 resulted in significantly smaller tumors compared to control. These studies are extremely encouraging as Minnelide is currently undergoing phase 1 clinical trials for gastrointestinal cancers.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background
Even after surgical resection, most patients with localized pancreatic ductal adenocarcinoma (PDAC) succumb to disease recurrence. Current animal models do not recapitulate this pattern of ...disease recurrence. Our goal was to develop a clinically relevant, immunocompetent model of PDAC resection to study recurrence and evaluate therapy.
Methods
Pancreatic cancer cells derived from tumors arising in KPC (
LSL-Kras
G12D/+
;
LSL-Trp53
R172H/+
;
Pdx-1-Cre
) mice were co-injected with stromal cells (pancreatic stellate cells) into the pancreas of immunocompetent mice to simulate the stroma-rich tumors seen in human PDAC. After allowing tumors to form, we resected these localized tumors and followed the mice for tumor recurrence. Circulating tumor cells (CTCs) were isolated, and systemic chemotherapy or immunotherapy was administered following tumor resection.
Results
Tumors formed by co-injection of KPC cells and stromal cells demonstrated a dense desmoplastic reaction similar to that seen in human disease. Resection at days 15 and 21 after implantation revealed uniform tumor volumes of 92 ± 19 mm
3
on day 15 and 444 ± 54 mm
3
on day 21. Histology of resected tumors showed negative margins. Resembling human PDAC, mice that underwent resection showed improved median survival (58 vs 47 days) but most animals developed intra-abdominal recurrence on follow-up. Adjuvant chemotherapy (median survival 69 vs 58 days), but not immunotherapy (median survival 69 vs 65 days) tended towards improved survival as seen in human disease. Circulating tumor cells were reliably identified from mice with and without resection, suggesting utility of this model in studying tumor metastases and recurrence.
Conclusion
We describe an immunocompetent animal model that recapitulates human disease in morphology and recurrence patterns. We show that it can be used to evaluate therapy in clinical scenarios associated with surgical resection and may help characterize factors responsible for disease recurrence.
Abstract
Development of therapeutic strategies to prevent recurrence in cancer patients, or tumor progression in at risk individuals has been challenging given the long and often unpredictable time ...to the emergence of the malignant tumors. Neoantigens represent the most potent antigens to induce antitumor immunity, yet the ability to predict which neoantigens will be expressed in future tumors is at present not an option. We have developed a simple and broadly applicable approach to induce neoantigens in tumor cells in situ by reducing the expression of antigen processing mediators like TAP, ERAAP, or invariant chain (Ii), using siRNAs that were targeted to tumor cells by conjugation to a nucleolin-binding aptamer. Exploiting the ability to induce neoantigens in situ, we describe a novel vaccination strategy targeting potent neoantigens to control the growth of the future tumors whereby patients in remission or individuals at risk are first vaccinated against the antigen processing downregulation-induced neoantigens and when or if tumor develops the same antigens are induced in the tumor, termed prorapeutic vaccination (prophylactic + therapeutic). Mice were vaccinated against the TAP downregulation-induced neoantigens by targeting the corresponding siRNAs to dendritic cells (DC) in situ via conjugation to a short CpG oligonucleotide (ODN); the CpG ODN also activated the targeted DC to avoid induction of tolerance against the neoantigens. Vaccination with CpG ODN-TAP siRNA conjugates inhibited subsequently implanted or autochthonous tumors in several tumor models, provided the said neoantigens were also induced in the tumor by nucleolin aptamer-targeted siRNA inhibition of TAP. The CpG-siRNA and nucleolin aptamer-siRNA conjugates are simple, chemically- synthesized, off-the-shelf, and broadly applicable reagents to vaccinate against neoantigens and control the growth of future tumors irrespective of their origin.
Citation Format: Greta Garrido Hidalgo, Brett Schrand, Ailem Rabasa, Agata Levay, Alexey Berezhnoy, Shrey Modi, Giri Bhuwan Bhuwan, Vikas Dudeja, Elien Doorduijn, Thorbald van Hall, Eli Gilboa. Vaccination against neoantigens induced in future tumors in the setting of recurrence and premalignancy 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 264.
Endoplasmic reticulum (ER) stress initiates an important mechanism for cell adaptation and survival, named the unfolded protein response (UPR). Severe or chronic/prolonged UPR can breach the ...threshold for survival and lead to cell death. There is a fundamental gap in knowledge on the molecular mechanism of how chronic ER stress is stimulated and leads to cell death in pancreatic ductal adenocarcinoma (PDAC). Our study shows that downregulating specificity protein 1 (Sp1), a transcription factor that is overexpressed in pancreatic cancer, activates UPR and results in chronic ER stress. In addition, downregulation of Sp1 results in its decreased binding to the ER stress response element present in the promoter region of Grp78, the master regulator of ER stress, thereby preventing homeostasis. We further show that inhibition of Sp1, as well as induction of ER stress, leads to lysosomal membrane permeabilization (LMP), a sustained accumulation of cytosolic calcium, and eventually cell death in pancreatic cancer.
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