Maria Giovanna Francipane

Cancer Stem Cells: A Moving Target

Even though the number of anti-cancer drugs entering clinical trials and approved by the FDA has increased in recent years, many cancer patients still experience poor survival outcome. The main explanation for such a dismal prognosis is that current therapies might leave behind a population of cancer cells with the capacity for long-term self-renewal, so-called cancer stem cells (CSCs), from which most tumors are believed to be derived and fueled. The CSCs might favor local and distant recurrence even many years after initial treatment, thus representing a potential target for therapies aimed at improving clinical outcome. In this review, we will address the CSC hypothesis with a particular emphasis on its current paradigms and debates, and discuss several mechanisms of CSC resistance to conventional therapies.

Therapeutic potential of mTOR inhibitors for targeting cancer stem cells

The mammalian target of rapamycin (mTOR) pathway is aberrantly activated in many cancer types. As the intricate network of regulatory mechanisms controlling mTOR activity is uncovered, more refined drugs are designed and tested in clinical trials. While first generation mTOR inhibitors have failed to show clinical efficacy due partly to the feedback relief of oncogenetic circuits, newly developed inhibitors show greater promise as anti-cancer agents. An effective drug must defeat the cancer stem cells (CSCs) while sparing the normal stem cells. Due to its opposing role on normal and malignant stem cells, mTOR lends itself very well as a therapeutic target. Indeed, a preferential inhibitory effect on CSCs has already been shown for some mTOR inhibitors. These results provide a compelling rationale for the clinical development of mTOR-targeted therapies.

Maturation of embryonic tissues in a lymph node: a new approach for bioengineering complex organs

Given our recent finding that the lymph node (LN) can serve as an in vivo factory to generate complex structures like liver, pancreas, and thymus, we investigated whether LN could also support early development and maturation from several mid-embryonic (E14.5/15.5) mouse tissues including brain, thymus, lung, stomach, and intestine. Here we observed brain maturation in LN by showing the emergence of astrocytes with well-developed branching processes. Thymus maturation in LN was monitored by changes in host immune cells. Finally, newly terminally differentiated mucus-producing cells were identified in ectopic tissues generated by transplantation of lung, stomach and intestine in LN. Thus, we speculate the LN offers a unique approach to study the intrinsic and extrinsic differentiation potential of cells and tissues during early development, and provides a new site for bioengineering complex body parts.

Pluripotent Stem Cells to Rebuild a Kidney: The Lymph Node as a Possible Developmental Niche.

Kidney disease poses a global challenge. Stem cell therapy may offer an alternative therapeutic approach to kidney transplantation, which is often hampered by the limited supply of donor organs. While specific surface antigen markers have yet to be identified for the analysis and purification of kidney stem/progenitor cells for research or clinical use, the reprogramming of somatic cells to pluripotent cells and their differentiation into the various kidney lineages might represent a valuable strategy to create a renewable cell source for regenerative purposes. In this review, we first provide an overview of kidney development and explore current knowledge about the role of extra- and intrarenal cells in kidney repair and organogenesis. We then discuss recent advances in the 1) differentiation of rodent and human embryonic stem cells (ESCs) into renal lineages; 2) generation of induced pluripotent stem cells (iPSCs) from renal or nonrenal (kidney patient-derived) adult cells; 3) differentiation of iPSCs into renal lineages; and 4) direct transcriptional reprogramming of adult renal cells into kidney progenitor cells. Finally, we describe the lymph node as a potential three-dimensional (3D) in vivo environment for kidney organogenesis from pluripotent stem cells.

Toward Organs on Demand: Breakthroughs and Challenges in Models of Organogenesis

Purpose of ReviewIrreversible organ failure remains a worldwide concern as demand for transplantable organs far outpaces the available supply. Apart from the demand for replacement organs to use to treat irreversible organ failure in civilian, there is a need of tissues or organs for wounded soldiers returning from battle. This review will discuss traditional three-dimensional (3D) cell culture techniques as well as newly developed technology platforms for the generation of transplantable tissues and organs on demand.Recent FindingsSince their discovery, stem cells have held great promise for their application in tissue regenerative medicine. Considerable effort is presently being invested in establishing methods for engineering physiologically relevant organs, where the chemical, physical and mechanical microenvironment of the stem cell niche can be replicated.SummaryThe recently established methods provide new possibilities in the creation of human body parts and provide more accurate predictions of tissue response to drug and chemical challenges. Given the rapid advancement in the human-induced pluripotent stem cell (iPSC) field, these platforms also hold great promise in the engineering of transplantable tissues and organs, capable of benefitting patients with end-stage chronic organ failure or wounded warrior.

A Study of Cancer Heterogeneity: From Genetic Instability to Epigenetic Diversity in Colorectal Cancer

Cancer is the leading cause of death worldwide. Despite improvements in diagnosis and treatment over the past two decades, cancer continues to present a serious challenge to oncologists, especially when the disease has already spread to a distant site at the time of diagnosis. The high degree of variation in gene expression, observed not only in tumors arising from different tissues but also in tumors arising from the same tissue, and sometimes in distinct areas of the same tumor, is likely to be responsible for evolutionary adaptation and consequently tumor survival.

Regenerating a kidney in a lymph node

The ultimate treatment for end-stage renal disease (ESRD) is orthotopic transplantation. However, the demand for kidney transplantation far exceeds the number of available donor organs. While more than 100,000 Americans need a kidney, only 17,000 people receive a kidney transplant each year (National Kidney Foundation’s estimations). In recent years, several regenerative medicine/tissue engineering approaches have been exploited to alleviate the kidney shortage crisis. Although these approaches have yielded promising results in experimental animal models, the kidney is a complex organ and translation into the clinical realm has been challenging to date. In this review, we will discuss cell therapy-based approaches for kidney regeneration and whole-kidney tissue engineering strategies, including our innovative approach to regenerate a functional kidney using the lymph node as an in vivo bioreactor.

Abstract LB-C10: Identification of Therapeutic Targets for Chemotherapy-Resistant Colon Cancer Stem Cells

Current first-line chemotherapy generally consists of cytotoxic agents. While these agents may initially control disease by effectively debulking tumors, the tumors invariably recur due to the ability of cancer stem cells (CSCs) to survive and repopulate the tumor mass. To identify potential molecular targets in 5-fluorouracil (5-FU) refractory CSCs, we developed 5-FU resistant cell lines over a period of a year. Here we show that 5-FU maintains colon CSCs in an undifferentiated state in vitro. While untreated control cells passaged in parallel progressively acquired a differentiated morphology comprising crypt-villus structures, cells treated with an IC50 dose or escalating doses of 5-FU organized in round colonies with defined edges. Cells from these chemoresistant colonies exhibited a high nucleus-to-cytoplasm ratio and prominent nucleoli, features of pluripotent stem cells. Chemoresistant cells showed a reduced proliferation rate with respect to their counterparts. While immunofluorescent analysis revealed chemoresistant cells expressed a panel of pluripotency markers, flow cytometric analysis indicated a change in CD antigens associated with tumorigenicity and pluripotency in chemoresistant cells as compared to untreated cells. These results suggest colon CSCs, while under the selective pressure of chemotherapy in vitro, are likely to display an adaptive plasticity resembling fate reprogramming. Three-dimensional growth in Matrigel revealed untreated cells were able to arrange themselves in a ring around a well-defined central lumen. Conversely, chemoresistant cell-derived organoids had poorly defined or no central lumens. While untreated cells generated fast-growing, well-differentiated tumors, resistant cells generated slow-growing, moderately differentiated tumors in vivo. Finally, a large number of genes were screened in cell/tissue from both groups using Real-Time PCR arrays. Through this analysis, we identified molecular targets that might assist in the development of therapeutic strategies which will counteract the mechanisms of chemoresistance. Citation Format: Maria Giovanna Francipane, Denis Bulanin, Eric Lagasse. Identification of Therapeutic Targets for Chemotherapy-Resistant Colon Cancer Stem Cells. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr LB-C10.