Two Open Access reviews

1) Cancer Stem Cells in Pancreatic Cancer by Qi Bao and 6 co-authors, including Karl-Walter Jauch and Christiane J Bruns, Cancers 2010(Aug 19); 2(3): 1629-41. [Full text PDF][Scribd entry][Part of the Special Issue Pancreatic Cancer]. Abstract:

Pancreatic cancer is an aggressive malignant solid tumor well-known by early metastasis, local invasion, resistance to standard chemo- and radiotherapy and poor prognosis. Increasing evidence indicates that pancreatic cancer is initiated and propagated by cancer stem cells (CSCs). Here we review the current research results regarding CSCs in pancreatic cancer and discuss the different markers identifying pancreatic CSCs. This review will focus on metastasis, microRNA regulation and anti-CSC therapy in pancreatic cancer.

2) The Emerging Role of the Phosphatidylinositol 3-Kinase/ Akt/Mammalian Target of Rapamycin Signaling Network in Cancer Stem Cell Biology by Alberto M Martelli and 4 co-authors, including James A McCubrey, Cancers 2010(Aug 18); 2(3): 1576-96. [Part of the Special Issue Cancer Stem Cells].

Comment: Review #2 is the first paper that has been published in the special issue on Cancer Stem Cells. As of August 20, 17 more contributions to this special issue are planned. Review #1, although about CSCs, is a contribution to a separate special issue on Pancreatic Cancer.

Selective targeting of neuroblastoma tumour-initiating cells

Selective targeting of neuroblastoma tumour-initiating cells by compounds identified in stem cell-based small molecule screens by Kristen M Smith and 16 co-authors, including David R Kaplan, EMBO Mol Med 2010(Aug 18) [Epub ahead of print][Full text]. Abstract:

Neuroblastoma (NB) is the most deadly extra-cranial solid tumour in children necessitating an urgent need for effective and less toxic treatments. One reason for the lack of efficacious treatments may be the inability of existing drugs to target the tumour-initiating or cancer stem cell population responsible for sustaining tumour growth, metastases and relapse. Here, we describe a strategy to identify compounds that selectively target patient-derived cancer stem cell-like tumour-initiating cells (TICs) while sparing normal paediatric stem cells (skin-derived precursors, SKPs) and characterize two therapeutic candidates. DECA-14 and rapamycin were identified as NB TIC-selective agents. Both compounds induced TIC death at nanomolar concentrations in vitro, significantly reduced NB xenograft tumour weight in vivo, and dramatically decreased self-renewal or tumour-initiation capacity in treated tumours. These results demonstrate that differential drug sensitivities between TICs and normal paediatric stem cells can be exploited to identify novel, patient-specific and potentially less toxic therapies.

See also: New Twist on Drug Screening to Treat Common Childhood Cancer, ScienceDaily, August 18, 2010. Excerpt:

A study led by scientists at The Hospital for Sick Children (SickKids) reveals a new method of identifying drugs to treat children suffering from fatal cancers for which an effective treatment has not been found. Rather than developing a new drug from scratch, which is a complicated and time-consuming process, they tried a different approach: in the lab, they tested existing drugs on cancer stem cells from young patients with neuroblastoma, one of the common cancers of infants and children.

A related blog post is: High-throughput cancer stem cell-based screening assay for therapeutic compounds by Alexey Bersenev, Stem Cell Assays, August 19, 2010 [FriendFeed entry].

Therapeutic implications of colon CSCs

Therapeutic implications of colon cancer stem cells by Eros Fabrizi and 3 co-authors, including Lucia Ricci-Vitiani, World J Gastroenterol 2010(Aug 21); 16(31): 3871-7. OA review. [FriendFeed entry][PubMed citation]. Abstract:

Colorectal cancer is the second most common cause of cancer-related death in many industrialized countries and is characterized by a heterogenic pool of cells with distinct differentiation patterns. Recently, the concept that cancer might arise from a rare population of cells with stem cell-like properties has received support with regard to several solid tumors, including colorectal cancer. According to the cancer stem cell hypothesis, cancer can be considered a disease in which mutations either convert normal stem cells into aberrant counterparts or cause a more differentiated cell to revert toward a stem cell-like behaviour; either way these cells are thought to be responsible for tumor generation and propagation. The statement that only a subset of cells drives tumor formation has major implications for the development of new targeted therapeutic strategies aimed at eradicating the tumor stem cell population. This review will focus on the biology of normal and malignant colonic stem cells, which might contribute to our understanding of the mechanisms responsible for tumor development and resistance to therapy.

Putative tumor-initiating progenitor cells predict poor lung cancer prognosis

Adult lung stem cells, vital to injury repair, associated with poor cancer prognosis, News release, UCLA Newsroom, August 17, 2010. Excerpts:

Adult stem cells that are vital for airway repair in the lung but that persist in areas where pre-cancerous lesions are found are associated with a poor prognosis in patients who develop cancer, even those with early-stage disease, researchers at UCLA's Jonsson Comprehensive Cancer Center have found.

.....

In this study, Gomperts and her team screened around 900 tumors removed from patients with non-small cell lung cancer at UCLA and the University of Texas' MD Anderson Cancer Center, looking to see whether the adult stem cells could be found in the tumor. In her lab, Gomperts is now studying the pre-cancerous lesions where the adult stem cells persist in an attempt to uncover the cascade of molecular events that may transform these cells into lung cancer stem cells.

The news release is based on this publication: Presence of a Putative Tumor-Initiating Progenitor Cell Population Predicts Poor Prognosis in Smokers with Non–Small Cell Lung Cancer by Aik T Ooi and 19 co-authors, including Brigitte N Gomperts, Cancer Res 2010(Aug 15); 70(16): 6639-48. [PubMed citation][Full text]. Abstract:

Smoking is the most important known risk factor for the development of lung cancer. Tobacco exposure results in chronic inflammation, tissue injury, and repair. A recent hypothesis argues for a stem/progenitor cell involved in airway epithelial repair that may be a tumor-initiating cell in lung cancer and which may be associated with recurrence and metastasis. We used immunostaining, quantitative real-time PCR, Western blots, and lung cancer tissue microarrays to identify subpopulations of airway epithelial stem/progenitor cells under steady-state conditions, normal repair, aberrant repair with premalignant lesions and lung cancer, and their correlation with injury and prognosis. We identified a population of keratin 14 (K14)-expressing progenitor epithelial cells that was involved in repair after injury. Dysregulated repair resulted in the persistence of K14+ cells in the airway epithelium in potentially premalignant lesions. The presence of K14+ progenitor airway epithelial cells in NSCLC predicted a poor prognosis, and this predictive value was strongest in smokers, in which it also correlated with metastasis. This suggests that reparative K14+ progenitor cells may be tumor-initiating cells in this subgroup of smokers with NSCLC.

Partnership Pays Off

Northern Exposure by Emmet Pierce, San Diego Business Journal, August 16, 2010. Excerpt:

An example of San Diegans collaborating with Canadians is the work that has taken place at the UC San Diego Moores Cancer Center in cooperation with research at the University of Toronto. The partnership has enabled San Diego researchers to acquire a $20 million grant to develop drugs to be used against leukemia stem cells, Barr says.Dr. Catriona Jamieson, director of the stem cell research program at the Moores center, said scientists from Toronto and San Diego share "a deep and abiding interest in cancer stem cell biology." The Canadian consulate in San Diego was instrumental in helping to create a relationship in which both institutions would benefit, sharing information and applying for funds to support their research.

"The idea was to establish a Canada-California cancer stem cell initiative and obtain connections with Canadian funding agencies, particularly Genome Canada and the Ministry of Health," she said.

Jamieson added, "The most important thing is it allows people with disparate abilities and backgrounds to work together on the same problem."

Barr said the University of Toronto also was able to secure a $20 million research grant because of the collaboration, "so the team is greater than the sum of its parts."

Oxygen, hypoxia and the stem cell niche

Oxygen in Stem Cell Biology: A Critical Component of the Stem Cell Niche by Ahmed Mohyeldin, Tomás Garzón-Muvdi and Alfredo Quiñones-Hinojosa, Cell Stem Cell 2010(Aug 6); 7(2): 150-61. Review. [PubMed citation][FriendFeed entry]. Via Twitter @CellStemCell: Access [to the full text] is free in August worldwide so readers can try out new enhanced online format.

Abstract:

The defining hallmark of stem cells is their ability to self-renew and maintain multipotency. This capacity depends on the balance of complex signals in their microenvironment. Low oxygen tensions (hypoxia) maintain undifferentiated states of embryonic, hematopoietic, mesenchymal, and neural stem cell phenotypes and also influence proliferation and cell-fate commitment. Recent evidence has identified a broader spectrum of stem cells influenced by hypoxia that includes cancer stem cells and induced pluripotent stem cells. These findings have important implications on our understanding of development, disease, and tissue-engineering practices and furthermore elucidate an added dimension of stem cell control within the niche.