The role of CD133 in the identification and characterisation of tumour-initiating cells in non-small-cell lung cancer

CD24, a novel cancer biomarker, predicting disease-free survival of non-small cell lung carcinomas: a retrospective study of prognostic factor analysis from the viewpoint of forthcoming (seventh) new TNM classification

INTRODUCTION

Metastasis-associated protein CD24 has been identified as a new prognostic factor and stem cell marker in the human neoplasm. However, the importance of the CD24 in non-small cell lung carcinomas (NSCLCs) has not been elucidated well.

METHODS

We evaluated CD24 expression in 267 consecutive cases of NSCLC by immunohistochemistry using a tissue microarray technique and correlated with clinicopathologic parameters including forthcoming (seventh) new tumor node metastasis classification.

RESULTS

CD24-high expression was demonstrated in 87 of 267 (33%) and was associated with adenocarcinoma (ADC) histology than in squamous cell carcinoma histology (64 of 165 [39%] vs. 20 of 88 [23%]; p = 0.023). Patients with CD24-high tumors tended to have a higher risk of disease progression (p < 0.001) and cancer-related death (p = 0.002). Multivariate analysis proved CD24-high expression as independent prognostic factors of disease progression and cancer-related death (p = 0.002, hazard ratio = 1.78, 95% confidence interval = 1.23-2.58 and p = 0.017, hazard ratio = 1.93, 95% confidence interval =1.13-3.31). CD24-high expression had a tendency to correlate with new pathologic stage (p-stage) (p = 0.089) rather than old p-stage (p = 0.253). Performance status and new p-stage, regardless of the tumor histology, were identified as consistent independent prognostic factors of disease progression and cancer-related death. However, age was related to a significantly shorter cancer-specific survival in ADC only.

CONCLUSIONS

CD24 expression in NSCLC is associated with ADC histology and disease progression and cancer-related death, indicative of aggressive tumor behavior. Performance status and new p-stage, to a lesser extent, age correlated with progression-free survival and cancer-specific survival, regardless of tumor histology.

A cancer stem cell origin for human endometrial carcinoma?

Endometrial cancer (EC) is the most common gynaecological malignancy affecting women in the western world. Cancer stem cells (CSCs) are defined as a subset of tumour cells with the capacity to self-renew and give rise to the differentiated cells that comprise the bulk of the tumour. Given that a rare population of epithelial stem/progenitor cells has been identified in human endometrium, it is possible that these cells or their progeny may be the source of the putative CSCs that may initiate and maintain EC. Studies have shown that some cells within EC have the capacity to initiate clones that undergo self-renewing cell division and form tumoursin vivothat can be serially passaged, demonstrating self-renewal, proliferation and differentiation abilities of the potential EC stem cells (ECSCs). These potential ECSCs may be located within the tumour cell population expressing CD133 and/or within the side population. With the discovery of markers for ECSCs, it is hoped that ECSCs can be isolated and characterised, and that their role in the development of human EC will be further investigated. This knowledge opens the way for the development of new treatment modalities that target the CSCs, but spares normal endometrial stem/progenitor cells and other cells. Such treatments will be particularly useful for early-stage and pre-menopausal EC candidates where the uterus may be conserved, and for late-stage cases where hysterectomy is not curative and current treatments target the bulk tumour cells rather than CSCs.

Generation and characterization of non-small-cell lung cancer cell lines and clones for use in the study of immunotherapy

The in vitro study of cancer has been made easier by the use of stable tumor cell (TC) lines derived from patients to study antigen expression, immunogenicity, and response to both experimental and conventional therapeutic agents. However, the routine generation of these cell lines in some tumor histologies such as non-small-cell lung cancer (NSCLC) is difficult. In many cases, colonies of TCs do not survive, most likely due to a lack of critical growth factors in cell culture medium. Other times, TC colonies are overgrown by fibroblasts, which appear to have less stringent growth requirements. In some cases, cultures are overgrown by bacteria or mold contained in the biopsy arriving from the surgical or pathology suite. This study presents the characteristics of three new NSCLC cell lines and associated autologous clones generated from both adenocarcinoma and squamous cell carcinoma tissue. Different culture media and variable techniques were used to generate these stable TC lines. Limiting dilution analysis resulted in numerous clones, some of which displayed heterogeneity in terms of growth, antigen expression, and the ability to release cytokines. The successes and failures associated with generating TC lines are discussed in this article. Both parental cultures and related clones serve as critical reagents for the continued study of the cellular immune response to NSCLC.

Evidence for self-renewing lung cancer stem cells and their implications in tumor initiation, progression, and targeted therapy

The discovery of rare tumor cells with stem cell features first in leukemia and later in solid tumors has emerged as an important area in cancer research. It has been determined that these stem-like tumor cells, termed cancer stem cells, are the primary cellular component within a tumor that drives disease progression and metastasis. In addition to their stem-like ability to self-renew and differentiate, cancer stem cells are also enriched in cells resistant to conventional radiation therapy and to chemotherapy. The immediate implications of this new tumor growth paradigm not only require a re-evaluation of how tumors are initiated, but also on how tumors should be monitored and treated. However, despite the relatively rapid pace of cancer stem cell research in solid tumors such as breast, brain, and colon cancers, similar progress in lung cancer remains hampered in part due to an incomplete understanding of lung epithelial stem cell hierarchy and the complex heterogeneity of the disease. In this review, we provide a critical summary of what is known about the role of normal and malignant lung stem cells in tumor development, the progress in characterizing lung cancer stem cells and the potential for therapeutically targeting pathways of lung cancer stem cell self-renewal.

Neoplastic stem cells: current concepts and clinical perspectives

Neoplastic stem cells have initially been characterized in myeloid leukemias where NOD/SCID mouse-repopulating progenitors supposedly reside within a CD34+/Lin- subset of the malignant clone. These progenitors are considered to be self-renewing cells responsible for the in vivo long-term growth of neoplastic cells in leukemic patients. Therefore, these cells represent an attractive target of therapy. In some lymphoid leukemias, NOD/SCID mouse-repopulating cells were also reported to reside within the CD34+/Lin- subfraction of the clone. More recently, several attempts have been made to transfer the cancer stem cell concept to solid tumors and other non-hematopoietic neoplasms. In several of these tumors, the cell surface antigens AC133 (CD133) and CD44 are considered to indicate the potential of a cell to initiate permanent tumor formation in vivo. However, several questions concerning the phenotype, self-renewal capacity, stroma-dependence, and other properties of cancer- or leukemia-initiating cells remain to be solved. The current article provides a summary of our current knowledge on neoplastic (cancer) stem cells, with special emphasis on clinical implications and therapeutic options as well as a discussion about conceptual and technical limitations.