Pierre Cordelier

Multicellular tumor spheroid model to evaluate spatio-temporal dynamics effect of chemotherapeutics: application to the gemcitabine/CHK1 inhibitor combination in pancreatic cancer.

BackgroundThe multicellular tumor spheroid (MCTS) is an in vitro model associating malignant-cell microenvironment and 3D organization as currently observed in avascular tumors.MethodsIn order to evaluate the relevance of this model for pre-clinical studies of drug combinations, we analyzed the effect of gemcitabine alone and in combination with the CHIR-124 CHK1 inhibitor in a Capan-2 pancreatic cell MCTS model.ResultsCompared to monolayer cultures, Capan-2 MCTS exhibited resistance to gemcitabine cytotoxic effect. This resistance was amplified in EGF-deprived quiescent spheroid suggesting that quiescent cells are playing a role in gemcitabine multicellular resistance. After a prolonged incubation with gemcitabine, DNA damages and massive apoptosis were observed throughout the spheroid while cell cycle arrest was restricted to the outer cell layer, indicating that gemcitabine-induced apoptosis is directly correlated to DNA damages. The combination of gemcitabine and CHIR-124 in this MCTS model, enhanced the sensitivity to the gemcitabine antiproliferative effect in correlation with an increase in DNA damage and apoptosis.ConclusionsThese results demonstrate that our pancreatic MCTS model, suitable for both screening and imaging analysis, is a valuable advanced tool for evaluating the spatio-temporal effect of drugs and drug combinations in a chemoresistant and microenvironment-depending tumor model.

Pharmacological targeting of the protein synthesis mTOR/4E‐BP1 pathway in cancer‐associated fibroblasts abrogates pancreatic tumour chemoresistance

Pancreatic ductal adenocarcinoma (PDAC) is extremely stroma‐rich. Cancer‐associated fibroblasts (CAFs) secrete proteins that activate survival and promote chemoresistance of cancer cells. Our results demonstrate that CAF secretome‐triggered chemoresistance is abolished upon inhibition of the protein synthesis mTOR/4E‐BP1 regulatory pathway which we found highly activated in primary cultures of α‐SMA‐positive CAFs, isolated from human PDAC resections. CAFs selectively express the sst1 somatostatin receptor. The SOM230 analogue (Pasireotide) activates the sst1 receptor and inhibits the mTOR/4E‐BP1 pathway and the resultant synthesis of secreted proteins including IL‐6. Consequently, tumour growth and chemoresistance in nude mice xenografted with pancreatic cancer cells and CAFs, or with pieces of resected human PDACs, are reduced when chemotherapy (gemcitabine) is combined with SOM230 treatment. While gemcitabine alone has marginal effects, SOM230 is permissive to gemcitabine‐induced cancer cell apoptosis and acts as an antifibrotic agent. We propose that selective inhibition of CAF protein synthesis with sst1‐directed pharmacological compounds represents an anti‐stromal‐targeted therapy with promising chemosensitization potential.

Targeting KRAS for diagnosis, prognosis, and treatment of pancreatic cancer: Hopes and realities

Mutation of the KRAS oncogene in pancreatic cancer is responsible for permanent activation of the P21 RAS protein and the cascade of signalling pathways. Consequently, multiple cellular processes, such as transformation, proliferation, invasion, and survival are activated. The aim of this review was to present all potential clinical applications of targeting KRAS in terms of diagnosis and management of pancreatic adenocarcinoma. Quantitative polymerase chain reaction technology provides reliable assessment of KRAS mutations, both in tissues and from fine-needle aspiration biopsies. Numerous studies report that the combination of endoscopic ultrasound-guided cytopathology and a KRAS mutation assay can improve the positive and differential diagnosis of pancreatic cancer, differentiating between benign versus malignant solid pancreatic cancer, and reducing false-negative results compared to cytopathology alone. In addition, the presence of a KRAS mutation is frequently associated with a worse prognosis, both in cases of advanced and resected tumours. However, the KRAS mutation assay is not as efficient at predicting a response to both anti-epidermal growth factor receptor treatments and/or chemotherapy. Targeting of KRAS to treat pancreatic adenocarcinoma has been applied at different stages of RAS molecular intracellular processes: at the transcription level with antisense or interference RNA, at the posttranslational level with inhibitors of farnesyl transferase or anti-RAS vaccination peptides, and to target multiple signalling pathways using inhibitors of mitogen-activated protein kinase, phosphoinositide 3-kinase, AKT, mammalian target of rapamycin, RAF. Despite some encouraging results at pre-clinical and phase I stages, no significant clinical benefits have been observed. Combinatory approaches with standard chemotherapy will be welcome.

First-in-man Phase 1 Clinical Trial of Gene Therapy for Advanced Pancreatic Cancer: Safety, Biodistribution, and Preliminary Clinical Findings

This phase 1 trial was aimed to determine the safety, pharmacokinetics, and preliminary clinical activity of CYL-02, a nonviral gene therapy product that sensitizes pancreatic cancer cells to chemotherapy. CYL-02 was administrated using endoscopic ultrasound in 22 patients with pancreatic cancer that concomitantly received chemotherapy (gemcitabine). The maximum-tolerated dose (MTD) exceeded the maximal feasible dose of CYL-02 and was not identified. Treatment-related toxicities were mild, without serious adverse events. Pharmacokinetic analysis revealed a dose-dependent increase in CYL-02 DNA exposure in blood and tumors, while therapeutic RNAs were detected in tumors. No objective response was observed, but nine patients showed stable disease up to 6 months following treatment and two of these patients experienced long-term survival. Panels of plasmatic microRNAs and proteins were identified as predictive of gene therapy efficacy. We demonstrate that CYL-02 nonviral gene therapy has a favorable safety profile and is well tolerated in patients. We characterize CYL-02 biodistribution and demonstrate therapeutic gene expression in tumors. Treated patients experienced stability of disease and predictive biomarkers of response to treatment were identified. These promising results warrant further evaluation in phase 2 clinical trial.

CRISPR/Cas9: Transcending the Reality of Genome Editing

With the expansion of the microbiology field of research, a new genome editing tool arises from the biology of bacteria that holds the promise of achieving precise modifications in the genome with a simplicity and versatility that surpasses previous genome editing methods. This new technique, commonly named CRISPR/Cas9, led to a rapid expansion of the biomedical field; more specifically, cancer characterization and modeling have benefitted greatly from the genome editing capabilities of CRISPR/Cas9. In this paper, we briefly summarize recent improvements in CRISPR/Cas9 design meant to overcome the limitations that have arisen from the nuclease activity of Cas9 and the influence of this technology in cancer research. In addition, we present challenges that might impede the clinical applicability of CRISPR/Cas9 for cancer therapy and highlight future directions for designing CRISPR/Cas9 delivery systems that might prove useful for cancer therapeutics.

The SV2 variant of KLF6 is down-regulated in hepatocellular carcinoma and displays anti-proliferative and pro-apoptotic functions

BACKGROUND & AIMS KLF6 protein is a transcription factor that plays important functions in hepatocellular carcinoma (HCC), which is one of the leading causes of death by cancer worldwide. Previous studies showed the existence of three splice variants of KLF6, termed SV1, SV2, and SV3. An increased SV1/KLF6 mRNA ratio in HCC was already described. In this study, we aimed to investigate the expression of the SV2 variant in HCC samples and its role in hepatic cells. METHODS We measured the expression of the SV2 variant in HCC and adjacent tissue samples by q-RT-PCR. We established IHH and HepG2 stable cell lines over-expressing the SV2 variant and measured cell growth and apoptotic rate. RESULTS We observed a reduced expression of the SV2 variant in HCC samples versus surrounding tissues and normal liver. Interestingly, our findings demonstrate that the over-expression of the SV2 variant in IHH and HepG2 cells leads to a significant reduction of proliferation associated with cell death by apoptosis. We further demonstrate that the SV2 expression leads to an induction of the cell-cycle-controlling p21(CIP/WAF1) and the pro-apoptotic Bax genes, mediated by the p53 protein. We show further that the SV2 expression in IHH and HepG2 cells induces their sensitivity to the anti-cancer drug, gemcitabine. CONCLUSION We reveal a reduced expression of the SV2 variant of KLF6 in HCC samples and describe anti-proliferative and pro-apoptotic functions for this variant in hepatic cells.

The Rescue of miR-148a Expression in Pancreatic Cancer: An Inappropriate Therapeutic Tool

MicroRNAs are small non-coding RNAs that physiologically modulate proteins expression, and regulate numerous cellular mechanisms. Alteration of microRNA expression has been described in cancer and is associated to tumor initiation and progression. The microRNA 148a (miR-148a) is frequently down-regulated in cancer. We previously demonstrated that its down-regulation by DNA hypermethylation is an early event in pancreatic ductal adenocarcinoma (PDAC) carcinogenesis, suggesting a tumor suppressive function. Here, we investigate the potential role of miR-148a over-expression in PDAC as a therapeutic tool. We first report the consequences of miR-148a over-expression in PDAC cell lines. We demonstrate that miR-148a over-expression has no dramatic effect on cell proliferation and cell chemo-sensitivity in four well described PDAC cell lines. We also investigate the modulation of protein expression by a global proteomic approach (2D-DIGE). We show that despite its massive over-expression, miR-148a weakly modulates protein expression, thus preventing the identification of protein targets in PDAC cell lines. More importantly, in vivo data demonstrate that modulating miR-148a expression either in the epithelia tumor cells and/or in the tumor microenvironment does not impede tumor growth. Taken together, we demonstrate herein that miR-148a does not impact PDAC proliferation both in vitro and in vivo thus suggesting a weak potential as a therapeutic tool.

Endoscopic ultrasound-guided fine-needle aspiration plus KRAS and GNAS mutation in malignant intraductal papillary mucinous neoplasm of the pancreas

Background: KRAS and GNAS mutations are common in intraductal papillary mucinous neoplasia of the pancreas (IPMN). The aims of this study were to assess the role of pre-therapeutic cytopathology combined with KRAS and GNAS mutation assays within cystic fluid sampled by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) to predict malignancy of IPMN. Patients and methods: We prospectively included 37 IPMN patients with clinical and/or imaging predictors of malignancy (men: 24; mean age: 69.5 years). Cytopathology (performed on cystic fluid and/or IPMN nodules), KRAS (Exon 2, codon 12) and GNAS (Exon 8, codon 201) mutations assays (using TaqMan® allelic discrimination) were performed on EUS-FNA material. The final diagnosis was obtained from IPMN resections (n = 18); surgical biopsies, EUS-FNA analyses, and follow-up (n = 19): 10 and 27 IPMN were benign and malignant, respectively. Results: Sensitivity, specificity, positive and negative predictive values, and accuracy of cytopathology alone to diagnose IPMN malignancy were 55 %, 100 %, 100 %, 45 %, and 66 %, respectively. When KRAS-mutation analysis was combined with cytopathology these values were 92 %, 50 %, 83 %, 71 %, and 81 %, respectively. GNAS assays did not improve the performances of cytopathology alone or those of cytopathology plus a KRAS assay. Conclusions: In patients with a likelihood of malignant IPMN at pre-therapeutic investigation, testing for KRAS mutations in cystic fluid sampling by EUS-FNA improved the results of cytopathology for the diagnosis of malignancy whereas GNAS mutation assay did not.

The Promise of Gene Therapy for Pancreatic Cancer.

Unlike for other digestive cancer entities, chemotherapy, radiotherapy, and targeted therapies have, so far, largely failed to improve patient survival in pancreatic adenocarcinoma (PDAC), which remains the fourth leading cause of cancer-related death in Europe and the United States. In this context, gene therapy may offer a new avenue for patients with PDAC. In this review, we explore the research currently ongoing in French laboratories aimed at defeating PDAC using nonviral therapeutic gene delivery, targeted transgene expression, or oncolytic virotherapy that recently or will soon bridge the gap between experimental models of cancer and clinical trials. These studies are likely to change clinical practice or thinking about PDAC management, as they represent a major advance not only for PDAC but may also significantly influence the field of gene-based molecular treatment of cancer.

The E3 ubiquitin ligase Thyroid hormone Receptor-Interacting Protein 12 targets Pancreas Transcription Factor 1a for Proteasomal Degradation

Background: PTF1a is an essential transcription factor for pancreas development and function. Mechanisms regulating PTF1a degradation are unknown. Results: TRIP12 interacts with PTF1a. Its E3 ubiquitin ligase activity decreases protein stability of PTF1a. Conclusion: PTF1a is a new target of TRIP12. TRIP12 promotes proteasomal degradation of PTF1a and regulates PTF1a activities. Significance: TRIP12/PTF1a interaction could contribute to the regulation of pancreatic acinar cell homeostasis. Pancreas transcription factor 1a (PTF1a) plays a crucial role in the early development of the pancreas and in the maintenance of the acinar cell phenotype. Several transcriptional mechanisms regulating expression of PTF1a have been identified. However, regulation of PTF1a protein stability and degradation is still unexplored. Here, we report that inhibition of proteasome leads to elevated levels of PTF1a and to the existence of polyubiquitinated forms of PTF1a. We used the Sos recruitment system, an alternative two-hybrid system method to detect protein-protein interactions in the cytoplasm and to map the interactome of PTF1a. We identified TRIP12 (thyroid hormone receptor-interacting protein 12), an E3 ubiquitin-protein ligase as a new partner of PTF1a. We confirmed PTF1a/TRIP12 interaction in acinar cell lines and in co-transfected HEK-293T cells. The protein stability of PTF1a is significantly increased upon decreased expression of TRIP12. It is reduced upon overexpression of TRIP12 but not a catalytically inactive TRIP12-C1959A mutant. We identified a region of TRIP12 required for interaction and identified lysine 312 of PTF1a as essential for proteasomal degradation. We also demonstrate that TRIP12 down-regulates PTF1a transcriptional and antiproliferative activities. Our data suggest that an increase in TRIP12 expression can play a part in PTF1a down-regulation and indicate that PTF1a/TRIP12 functional interaction may regulate pancreatic epithelial cell homeostasis.