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Cioffi M.,Stem Cells and Cancer Group | Trabulo S.,Stem Cells and Cancer Group | Trabulo S.,Barts Cancer Institute | Hidalgo M.,Gastrointestinal Cancer Clinical Research Unit | And 8 more authors.
Clinical Cancer Research | Year: 2015

Purpose: Pancreatic ductal adenocarcinoma (PDAC) is a cancer of the exocrine pancreas with unmet medical need and is strongly promoted by tumor-Associated macrophages (TAM). The presence of TAMs is associated with poor clinical outcome, and their overall role, therefore, appears to be protumorigenic. The don't eat me signal CD47 on cancer cells communicates to the signal regulatory protein-A on macrophages and prevents their phagocytosis. Thus, inhibition of CD47 may offer a new opportunity to turn TAMs against PDAC cells, including cancer stem cells (CSC), as the exclusively tumorigenic population. Experimental Design: We studied in vitro and in vivo the effects ofCD47inhibition on CSCs using a large set of primary pancreatic cancer (stem) cells as well as xenografts of primary human PDAC tissue. Results: CD47 was highly expressed on CSCs, but not on other nonmalignant cells in the pancreas. Targeting CD47 efficiently enhanced phagocytosis of a representative set of primary human pancreatic cancer (stem) cells and, even more intriguingly, also directly induced their apoptosis in the absence of macrophages during long-Term inhibition of CD47. In patient-derived xenograft models, CD47 targeting alone did not result in relevant slowing of tumor growth, but the addition of gemcitabine or Abraxane resulted in sustained tumor regression and prevention of disease relapse long after discontinuation of treatment. Conclusions: These data are consistent with efficient in vivo targeting of CSCs, and strongly suggest that CD47 inhibition could be a novel adjuvant treatment strategy for PDAC independent of underlying and highly variable driver mutations. © 2015 American Association for Cancer Research.

Garrido-Laguna I.,University of Houston | Hidalgo M.,Gastrointestinal Cancer Clinical Research Unit | Kurzrock R.,University of Houston
Nature Reviews Clinical Oncology | Year: 2011

In the past, clinical phase I trials often suffered from low response rates and inadequate experimental drug doses. Over the past decade, however, phase I trials have evolved from simple dose-finding studies to trials that might provide clinically relevant therapeutic opportunities for patients with advanced-stage cancer for which no standard therapies are available. In the future, the routine use of modern technologies such as large-scale genome sequencing will help to unravel the specific biology of a patient's cancer. Such tools will expand our knowledge about genetic aberrations and might provide opportunities for the development of novel, molecular targeted therapies for patients with refractory cancer. Increasingly, the focus will likely turn from carrying out large randomized trials in unselected patients to conducting smaller biomarker-driven trials in selected patients with known molecular aberrations. We expect that these new strategies will enhance response rates as appropriate patients are targeted, therefore sparing those patients who are unlikely to benefit. © 2011 Macmillan Publishers Limited. All rights reserved.

Miranda-Lorenzo I.,Stem Cells and Cancer Group | Dorado J.,Stem Cells and Cancer Group | Lonardo E.,Stem Cells and Cancer Group | Alcala S.,Stem Cells and Cancer Group | And 13 more authors.
Nature Methods | Year: 2014

Cancer stem cells (CSCs) are thought to drive tumor growth, metastasis and chemoresistance. Although surface markers such as CD133 and CD44 have been successfully used to isolate CSCs, their expression is not exclusively linked to the CSC phenotype and is prone to environmental alteration. We identified cells with an autofluorescent subcellular compartment that exclusively showed CSC features across different human tumor types. Primary tumor-derived autofluorescent cells did not overlap with side-population (SP) cells, were enriched in sphere culture and during chemotherapy, strongly expressed pluripotency-associated genes, were highly metastatic and showed long-term in vivo tumorigenicity, even at the single-cell level. Autofluorescence was due to riboflavin accumulation in membrane-bounded cytoplasmic structures bearing ATP-dependent ABCG2 transporters. In summary, we identified and characterized an intrinsic autofluorescent phenotype in CSCs of diverse epithelial cancers and used this marker to isolate and characterize these cells. © 2014 Nature America, Inc.

Lonardo E.,Stem Cells and Cancer Group | Cioffi M.,Stem Cells and Cancer Group | Sancho P.,Stem Cells and Cancer Group | Sanchez-Ripoll Y.,Stem Cells and Cancer Group | And 5 more authors.
PLoS ONE | Year: 2013

Pancreatic ductal adenocarcinomas contain a subset of exclusively tumorigenic cancer stem cells (CSCs), which are capable of repopulating the entire heterogeneous cancer cell populations and are highly resistant to standard chemotherapy. Here we demonstrate that metformin selectively ablated pancreatic CSCs as evidenced by diminished expression of pluripotency-associated genes and CSC-associated surface markers. Subsequently, the ability of metformin-treated CSCs to clonally expand in vitro was irreversibly abrogated by inducing apoptosis. In contrast, non-CSCs preferentially responded by cell cycle arrest, but were not eliminated by metformin treatment. Mechanistically, metformin increased reactive oxygen species production in CSC and reduced their mitochondrial transmembrane potential. The subsequent induction of lethal energy crisis in CSCs was independent of AMPK/mTOR. Finally, in primary cancer tissue xenograft models metformin effectively reduced tumor burden and prevented disease progression; if combined with a stroma-targeting smoothened inhibitor for enhanced tissue penetration, while gemcitabine actually appeared dispensable. © 2013 Lonardo et al.

Cioffi M.,Stem Cells and Cancer Group | Trabulo S.M.,Stem Cells and Cancer Group | Sanchez-Ripoll Y.,Stem Cells and Cancer Group | Miranda-Lorenzo I.,Stem Cells and Cancer Group | And 10 more authors.
Gut | Year: 2015

Objective Cancer stem cells (CSCs) represent the root of many solid cancers including pancreatic ductal adenocarcinoma, are highly chemoresistant and represent the cellular source for disease relapse. However the mechanisms involved in these processes still need to be fully elucidated. Understanding the mechanisms implicated in chemoresistance and metastasis of pancreatic cancer is critical to improving patient outcomes. Design Micro-RNA (miRNA) expression analyses were performed to identify functionally defining epigenetic signatures in pancreatic CSC-enriched sphere-derived cells and gemcitabine-resistant pancreatic CSCs. Results We found the miR-17-92 cluster to be downregulated in chemoresistant CSCs versus non-CSCs and demonstrate its crucial relevance for CSC biology. In particular, overexpression of miR-17-92 reduced CSC self-renewal capacity, in vivo tumourigenicity and chemoresistance by targeting multiple NODAL/ACTIVIN/TGF-β1 signalling cascade members as well as directly inhibiting the downstream targets p21, p57 and TBX3. Overexpression of miR-17-92 translated into increased CSC proliferation and their eventual exhaustion via downregulation of p21 and p57. Finally, the translational impact of our findings could be confirmed in preclinical models for pancreatic cancer. Conclusions Our findings therefore identify the miR-17-92 cluster as a functionally determining family of miRNAs in CSCs, and highlight the putative potential of developing modulators of this cluster to overcome drug resistance in pancreatic CSCs.

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