Cancer Stem Cells: Formidable Allies of Cancer

Glioblastoma Microenvironment and Cellular Interactions

Simple Summary

This paper summarizes the crosstalk between tumor/non-tumor cells and other elements of the glioblastoma (GB) microenvironment. In tumor pathology, glial cells result in the highest number of cancers, and GB is considered the most lethal tumor of the central nervous system (CNS). The tumor microenvironment (TME) is a complex peritumoral hallo composed of tumor cells and several non-tumor cells (e.g., nervous cells, stem cells, fibroblasts, vascular and immune cells), which might be a key factor for the ineffective treatment since the microenvironment modulates the biologic status of the tumor with the increase in its evasion capacity. A deeper understanding of cell–cell interactions in the TME and with the tumor cells could be the basis for a more efficient therapy.

Abstract

The central nervous system (CNS) represents a complex network of different cells, such as neurons, glial cells, and blood vessels. In tumor pathology, glial cells result in the highest number of cancers, and glioblastoma (GB) is considered the most lethal tumor in this region. The development of GB leads to the infiltration of healthy tissue through the interaction between all the elements of the brain network. This results in a GB microenvironment, a complex peritumoral hallo composed of tumor cells and several non-tumor cells (e.g., nervous cells, stem cells, fibroblasts, vascular and immune cells), which might be the principal factor for the ineffective treatment due to the fact that the microenvironment modulates the biologic status of the tumor with the increase in its evasion capacity. Crosstalk between glioma cells and the brain microenvironment finally inhibits the beneficial action of molecular pathways, favoring the development and invasion of the tumor and its increasing resistance to treatment. A deeper understanding of cell–cell interactions in the tumor microenvironment (TME) and with the tumor cells could be the basis for a more efficient therapy.

Expression of Aldehyde Dehydrogenase (ALDH1) and ATP Binding Cassette Transporter G2 (ABCG2) in Iraqi Patients with Colon Cancer and the Relation with Clinicopathological Features

Tumor initiation cells or cancer stem cell markers ABCG2 and ALDH1 play pivotal roles in invasion, metastasis and resistance to cytotoxic agents. In this study, we evaluated the expression levels of ALDH1 and ABCG2 in Iraqi patients with colon cancer and/or benign colon tumors. We also investigated the association between the expression levels of these markers and patient clincopathological features. The expression levels of ALDH1 and ABCG2 in cancer tissues as well as in benign tumor samples were determined by immunohistochemistry using tumor tissues microarray of TNM (Tumor, Node, Metastasis) in 42 patients with colon cancer samples as well as in 18 corresponding benign tumors. Immunohistochemistry showed that ALDH1 and ABCG2 expression levels increased to 80% and 76%, respectively in colon cancer tissues as compared to 33% and 28% in benign tumor tissues. The expression levels of ALDH1 and ABCG2 were associated with tumor stages. No significant association was found between the expressions levels of these markers and tumor size, gender, patients' age, and lymph node involvement. These results indicate that the expression levels of ALDH1 and ABCG2 increased in colon cancer tissues compared to benign tumor tissues in Iraqi patients.

DCLK1 plays an important role in colorectal cancer tumorgenesis through the regulation of miR-200c

Doublecortin-like kinase 1 (DCLK1) is a protein kinase that is known as a specific cancer stem cell (CSC) marker in colorectal cancer (CRC). Deregulation of DCLK1 expression has been reported in various cancers. We measured the protein expression of DCLK1 in 38 CRC and normal colon samples by immunohistochemistry (IHC). HCT-116 and SW-48 cells were transfected with DCLK1 siRNA and analyzed for expression of DCLK1 and miR-200c. The effects of DCLK1 knockdown on cell migration, invasion, sphere-forming, and apoptosis were explored. It was found that DCLK1 protein expression levels were significantly higher in CRC tissue than in normal colon specimens. Silencing of DCLK1 significantly inhibited cell migration, invasion, and sphere-forming potential; it also induced apoptosis as well as increased expression of miR-200c. Furthermore, silencing of miR-200c significantly up-regulated DCLK1 expression. Overall, our data demonstrated that DCLK1 plays an important role in cancer progression and is involved in the regulation of miR-200c expression.