Cancer types CSC markers Other roles of such CSC markers Reference
Glioma/Medulloblastoma, head and Neck cancers, Lung, Prostate, Melanoma, Osteosarcoma ABCG2 (ATP-binding cassette transporter) ABCG2, also known as MXR, BCRP, or ABCP, is an efflux protein that plays a role in host detoxification of various xenobiotic substrates in various organs like liver, intestine, placenta, and blood brain barrier. Primitive CD34-Hematopoietic stem cells from bone marrow are reported to express ABCG2. Guo et al. [45]
Glioma/ Medulloblastoma, Head and neck cancers, Lung, Breast, Pancreas, Bladder, Prostate A1/ALDH1A1 (Aldehyde Dehydrogenase 1) ALDHs are NAD(P)+-dependent enzymes, which oxidize toxic aldehydes to carboxylic acids in the human system.ALDH1 oxidizes retinaldehyde to retinoic acid and acetaldehyde to acetic acid and is expressed in the epithelia of brain, liver, testis, eye lens and cornea. Also, ALDH1 is required for dopaminergic neuron, as well as, hematopoietic stem cell differentiation and development via retinoic acid formation. de Beça et al. [46]
Glioma/ Medulloblastoma, Head and neck cancers, Breast, Pancreas, Bladder, Prostate, Ovarian, Osteosarcoma, Leukemia CD44 CD44 is a multistructural and multifunctional cell surface molecule and hyaluronic acid receptor, whose role is primarily governed by various post translational modifications. CD44 is involved in cell proliferation, differentiation, migration, angiogenesis, presentation of cytokines, chemokines, and growth factors to the corresponding receptors, and docking of proteases at the cell membrane, as well as, in signaling for cell survival. Such biological properties are not only essential for the physiological activities of normal cells, but also, for the pathologic activities of cancer cells. de Beça et al. [46],
Wanget al. [47]
Breast, Pancreas, Liver, Oesophagus, Gastric CD24 Synonymously known as heat stable antigen (HSA) or epithelial specific antigen is a variably glycosylated GPI linked glycoprotein expressed on B and T immune cells, keratinocytes, myofibres and neuroblasts. It is also a marker of exosomes and is also discharged in urine and amniotic fluid. Another normal biological role of CD24 is binding to P-Selectin on activated platelets and vascular endothelial cells, deletion of autoreactive T cells and tumor cell apoptosis. CD24 is upregulated in various types of cancers. Wang et al. [48]
Glioblastomas, Prostate, Gastric, and Breast CD133/Prominin1 Synonymously known as Prominin 1(PROM1) is a member of pentaspan transmembrane glycoprotein having specific localization to cellular protrusions.Various somatic cell types that express CD133 are hematopoietic stem cells, endothelial progenitor cells, glial stem cells, kidney, mammary gland, salivary glands, testes and placental cells. However, CD133 is also reported being expressed by glioblastomas and pediatric brain tumors, gastric and breast CSCs. Yasuda et al. [49], Brescia et al. [50]
Osteosarcomas, Leukemia, ovarian cancers, Melanomas, Laryngeal cancers CD105/Endoglin Synonymously known as CD105, is an integral transmembrane glycoprotein that acts as a coreceptor for TGFBR2 that binds TGF-β, thereby mediating fetal vascular/ endothelial development under normal physiological conditions. Endoglin is a marker for angiogenesis. Accordingly, vascular endothelial cells, chondrocytes, and syncytiotrophoblasts of term placenta express high levels of endoglin. Besides, mesenchymal stem cells also express this protein. Also, endoglin is overexpressed in vascular endothelium in malignancies including ovarian, leukemia, gastrointestinal stromal tumors (GIST), melanoma, and laryngeal cancers. Non endothelial cells do not express endoglin. Taskiran et al. [51],
Marioni et al. [52]
Breast and Prostate Stem Cell Antigen (Sca-1) This is a glycosyl phosphatidylinositol-anchored cell surface protein (GPI-AP) of the Ly6 gene family. Since past 20 years, this protein is being used extensively to purify murine hematopoietic stem cells. Also, due to the fact that many different stem cell types share common biochemical pathways have led to the search of Sca-1 is various adult, as well as, cancer stem cells. Sca-1 is reportedly expressed by a mixture of stem, progenitor, and differentiated cell types in a wide variety of tissues and organs. Hence, Sca-1 is used routinely in combination with negative selection against mature markers for enrichment of stem and progenitor cells. Regarding cancer stem cells expressing Sca-1, this is reportedly associated withprogression and malignancy of prostate cancer associated with increased AKT overexpression. Xin et al. [53],
Witz IP. [54],
Miles et al. [55]
Table 2: A comprehensive list of common marker proteins of CSCs, their occurrences, and their roles in normal biological processes is represented.