Proceedings of The 1stSyiah Kuala International Conference on Medical and Health Sciences May 11-12, 2017, Banda Aceh, Indonesia

Cancer Stem : The New Role of

1Dedy Syahrizal*

1Department Biochemistry, Medical Faculty, Syiah Kuala University, Banda Aceh, 23116, Indonesia *Corresponding Author: [email protected]

Abstract Formerly is seen as a disease caused by changes in the nature of a normal cell into abnormal cells that have the ability to proliferate uncontrollably. Through a series of studies proven that the view is not true. This condition because only a small portion of the cells of cancer can cause similar cancerous states when transplanted. The cells have characteristics as stem cells with a variety of specific cell surface markers. Cancer stem cells have indeed been present in the body but under normal circumstances will not be activated to proliferate and differentiate. Conditions that alter the microenvironment of cancer stem cells are suspected as the cause of the activation of cancer stem cells. The activation mechanism of the cancer stem cells involves a variety of signaling cells that cause cancer stem cells to have the ability to proliferate uncontrollably. Recent research has shown that cancer stem cells have the ability to and radiation resistance that cause a cancer difficult to treat. The knowledge of the various molecular markers on cancer stem cells is a key asset for understanding the nature and mechanism of the viability of these cells so that they can serve as guidance on interventions that are useful for treating a cancer.

Key words: cancer , microenvironment, biomarkers, carcinogenesis, chemotherapy resistency

Preface

In the past, experts have suggested that tumor mass is formed by populations that have similar maturity and metastatic potential. Earlier understanding only revealed that cancer cells are normal cells that have abnormalities that fail to achieve maturity function and result in the ability of uncontrolled cell . A number of research prove the theory of similarity maturity level and the potential cancer cells that make up the tumor mass began to be abandoned. Some scientific literature concludes that the population of cancer cells has a hierarchy like normal cells. The highest level of cancer cell hierarchy is occupied by cell subpopulations that are shown to have the potential to perform both symmetric and asymmetric . The potential for symmetrical and asymmetric division is one of the characteristics of the stem cell. Therefore, it is very natural that the subpopulation of cancer cells that have this capability is called a cancer stem cell (CSC)1.

Just like a normal stem cell, CSC are also already present in the human body. In normal circumstances the CSC are inactive and newly activated when the microenvironment of the cell changes to the right conditions for proliferation and differentiation. The changes in the microenvironment will enable some of the cellular signaling responsible for cancer stem cell activation. Knowledge of the biomarkers of a CSC and the regulation of biomolecules in

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Proceedings of The 1stSyiah Kuala International Conference on Medical and Health Sciences May 11-12, 2017, Banda Aceh, Indonesia

both the microenvironment and the internal cells is essential to determine the properties and capabilities of a CSC. Several studies have shown that CSC have a high anti apoptotic ability that can even be resistant to chemotherapy and radiotherapy. In addition, CSC is also estimated to have a major contribution to the metastasis process of a cancer. These CSC phenomena become an interesting thing to discuss and require approaches ranging from basic science to clinical management.

CSC Concept

The concept of cancer stem cells (CSC) arose from the discovery that a majority of cells from some human (), at different stages of differentiation, originated from transformed undifferentiated pluripotent stem cell. This led to the hypothesis, then the theory, that as in the normal somatic stem cells (SSC) and their derived tissues, a small population of cells, the cancer stem cells (CSC) would reproduce ad infinitum and generate the very diverse, limited lifespan, multi-lineage differentiated majority of cells in a cancer, called the derived population cells (DC) (Fig. 1). This was the concept of an aberrant stem cell system, a system gone awry. In agreement with such a scheme, CSC were assumed to originate from somatic stem cells (SSC) and to represent a minor, qualitatively distinct, eternal population, transforming deterministically and irreversibly in a limited lifespan, more or less differentiated hierarchy of derived cells that would constitute the bulk of phenotypically diverse cancer cell populations2.

Figure 1. Cancer stem cell model compared with stochastic model2

The expression of a distinctive repertoire of surface markers is an operational prerequisite for the isolation of the CSC population. However, it should be noted that the markers proposed are different for the different types of and different from those of SSC. Their potential biological role is little considered and it is implicitly assumed that they permanently mark the same cells. The selective endowment of a tumorigenic capacity implies that cancers contain at least two populations of cells, one being the CSC, which self- renew and are immortal, and the other being the derived population, which has a limited life span and therefore should be considered as an almost innocuous by-product. Many researchers, using the cell sorting vocabulary, call the putative CSC, the side population which for an initiating group is counterintuitive. This criterion overlaps the third one, whereby the CSC population sustains the growth of heterogenous cancer tissue, recreating the full repertoire of cancer cell population i.e. a hierarchy of differentiated derived lineages3.

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Proceedings of The 1stSyiah Kuala International Conference on Medical and Health Sciences May 11-12, 2017, Banda Aceh, Indonesia

Another concept that developed and is still being debated to this day is CSC basically constitute a type of stem cells that already exist separately on each network. This cell will develop when there is a stimulus that can change the microenvironment of the CSC into a suitable place to grow. This opinion is still controversial because some markers from CSC are also markers for normal stem cells such as embryonic stem cells and adult stem cells

CSC Biomarker

CSCs have been identified in different cancers in avariety of frequencies using combinations of cell surface antigens as well as soluble proteins.The ability of these markers to physically isolate distinct subpopulations of neoplastic cells with differing biological features further represents the most compelling evidence that tumour cells can reside in multiple,alternative phenotypic states with in a given cancer and explains the of intra-.Several cell-surface molecules which are used for the isolation of CSCs represent cell-surface antigens that are expressed by their corresponding adult stemcells4.

The systematical review conducted by Islam 2015 suggests several biomarkers of CSC from the following cases of cancer (Table 1).

Table 1. Commonly CSC markers in different cancers type 4

Name of Marker Normal Functions Reported Cancers ALDH Conversion of aldehyde to Breast, colon, head and neck, carboxylic acid involved in ester , , () hydrolysis and signalling pathway CD44 Cell adhesion and migration, cell- Breast, colon, stomach, head and cell interactions, cell signalling, neck, liver, , pancreas, leucocyte attachment and rolling CD90 Cell adhesion and signal , liver, breast, and transduction in T cells CD24 proliferation and maturation Breast, stomach, pancreas Hedgehog-Gli , tissue Breast, colon activity regeneration and maintenance CD38 Signal transduction, calcium Haematological signalling and cell adhesion α6-Integrin Cell adhesion, cell-surface Breast, prostate, brain () mediated signalling ABCB5 Transmembrane transport of Colon, skin (melanoma), molecules β-Catenin activity Cell-cell adhesion, transcriptional Colon, liver, ovary, breast, lung, regulator brain () CD26 signal transduction Colon, leukaemia CD29 Cell adhesion, epithelial to Breast, colon mesenchymal transition CD133 Regulates cell membrane topology Brain, colon, endometrium, liver, lung, ovary, pancreas, prostate and breast CD166 Cell adhesion and cell-cell Colon, lung interactions LGR5/ GPR49 Cell adhesion Colon CD15 Cell adhesion, migration, Brain (glioma), Hodgkin's

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Proceedings of The 1stSyiah Kuala International Conference on Medical and Health Sciences May 11-12, 2017, Banda Aceh, Indonesia

phagocytosis and chemotaxis Nestin Remodelling of the cell Brain (glioma), prostate CD13 Regulate peptides and lipid Liver turnover ABCG2 transport various molecules Lung, breast, brain across extra- and intra- cellular membranes CD20 Regulates B cell differentiation Skin (melanoma) CD271 Regulates neuronal cell Skin (melanoma), head and neck differentiation and survival C-met Regulates invasive growth Pancreas, Breast CXCR4/CD184 Regulates chemotactic activity of Lung, ovarian lymphocytes Nodal activity Cell differentiation and signal Pancreatic transduction Trop2 Signal transduction Prostate CD98 Membrane transporter regulate Head and neck amino acid transport Keratin 5(K5) Structural framework of Bladder, lung keratinocytes P63 Transactivation, regulate Bladder apoptosis BMI-1 Cell division and stem cell renewal Bladder, skin, prostate, ovary, breast, colon OCT-4 Maintenance of stem cell Bladder, breast pluripotency OCT-3/4 Regulates stem cell identity and Liver, breast cell fate Ep-CAM Cell adhesion, migration, Colon, pancreas, liver signalling KIT/CD117 Cell signal transduction Ovary CD34 Regulation of cell adhesion Haematological Side-population Efflux of dye via ABC transporter Brain(glioma),gastrointestinaltract, (Hoechst33342dye liver,lung,thyroid exclusion)

Difference Between Normal Stem Cell And Cancer Stem Cell

Basically CSC and normal stem cells have the same characteristics. To understand CSC we must understand the stem cell normally first. Stem cells are cells that are the beginning of other that make up the whole of the organism's body. In order to be classified as a stem cell, a cell must possess an undifferented characteristics, self-renewal and capable of differentiating into more than one type of cell (multipotent / pluripotent). The difference between CSC and normal stem cell is the difference of micro environment of both types of stem cell1,5.

The micro environments (niche) are basal membranes, extra cell matrix components, cell membranes and factors produced by a part or body compartment. The ability of CSC to play a role in the intended microenvironment depends on external signals and specific cell regulation. Cell intrinsic regulation includes factors that control cell division by asymmetry, gene expression involving uncommitted and commited roles, and cell cycle in certain cell

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Proceedings of The 1stSyiah Kuala International Conference on Medical and Health Sciences May 11-12, 2017, Banda Aceh, Indonesia

groups. It can be concluded that extrinsic signals play a role in controlling the CSC so that it can function in accordance with its microenvironment and affect the niche 5,6.

Niche interacts well with signals from nearby environments as well as from distant environments. Until now there is no known definite characteristics of micro environments that can affect CSC either from or from other networks. Allegedly there are several kinds of modulator that can control CSC. The next modulator plays a role to make a temporary relationship with its micro environment. Therefore, it needs to be studied more about the role of molecule and cell in micro environment and its role to CSC function so that it can be known the role of micro environments on the growth of cancer (Fig. 2) 5,6.

Figure 2. Role of nichestem cell in physiological condition and in cancer condition5

A compatible niche to support CSC growth has been extensively researched. Celluar signaling allegedly has an important role to play in this. From several studies it is known that there are celular signallings like WNT, hedgehog, Notch, PI3K / Akt, STAT and NFkB. These overall signaling pathways in addition to contributing not only to the proliferation and differentiation of CSC but also affect CSC's ability to survive from apoptotic process7,8,9.

CSC and antiapoptosis

CSC's ability to withstand apoptotic processes causes these cells to be resistant to cancer therapy. The underlying mechanisms are not yet fully understood, but some key proteins have been identified. IGF-1 and IL-6 are known to activated Akt and NFkB expression. Activated Akt will increase the secretion of frizzled-related protein 2 that is a member of the Wnt communication pathway, but until now no clear explanation of frizzled-related protein 2 has been found. Frizzled-related protein 2 works dependently or independently for the antiapoptotic effect. It is well known that the antiapoptosis effect causes increased expression of Bcl-2, Bcl-xL and heat shock proteins. In anti apoptotic conditions associated with hypoxia it is reported that there is an increase in VEGF. The VEGF, HGF and TGF-β1 have a role in reversing the process of apoptosis in endothelial cells10,11.

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Proceedings of The 1stSyiah Kuala International Conference on Medical and Health Sciences May 11-12, 2017, Banda Aceh, Indonesia

Research has shown that when given chemotherapy or radiation CSC actually produce Heat shock protein (HSP) 12. HSP has a strong cytoprotective effect and behaves as a chaperone molecule for other cell proteins. HSP is named according to its molecular weight. HSPs that are often associated with CSC antiapoptosis properties are HSP27, 70 and 90. As antipoptotic proteins HSP27, 70 and 90 protect cells from the cytotoxic effects of TNF, monocytes, oxidative stress, chemotherapeutic agents, ceramide and radiation. HSP70 inhibits Bax translocation from cytosol to mitochondria when apoptotic cascade is stimulated by nitric oxide and heat stress 13.

Heat shock protein 70 (HSP70) inhibits apoptosom formation by binding to Apaf-1. HSP70 prevents late caspase dependent events such as activation of the cytosolic A2 phospholipase, further inhibiting the activation of caspase 3. On independent pathways, HSP70 binds to Apoptosis Inducing Factor (AIF) which escapes from mitochondria and prevents it from translocation into the nucleus. In addition to apotosis, HSP70 may inhibit necrosis by inhibition of JNK, Bax, and caspase 3 14.

CSC and metastasis The ability of CSCs to metastasize is strongly influenced by the ability of these cells to perform migration and homming. The microenvironment (niche) involves a series of supporting cells, cytokines, signaling pathways and cell attachment molecules. In order to process a migration, a substance that can release the bond between the stem cell and the cell attachment molecule in its matrix. There are several types of cell attachment molecules that keep stem / progenitor cells in their matrix such as a kit with ligand kit, CD44 with , CD 62 with PSGL, VLA4 with VCAM-1 and CXCR4 with SDF 1. This bond will be released when exposed to Cytokines and subcellular proteins that are the result of inflammatory and ischemic processes such as IL-8 and norepinephrine. Furthermore, the detached stem / progenitor cells will follow the corresponding signals they are getting. Several studies have suggested that some molecules may act as chemoattractants such as VEGF, CXCL12, IL-6, MMIF, Integrin and PDGF. Given the signal given by a substance that acts as a chemoattractan then CSC will mobilize at the location of the source of chemoattractan and will eventually do homming on the spot to further develop into cancer cells in accordance with the stimulus it receives 15.

Management of CSC Knowledge of the properties, biomarkers, microenvironment and intracellular molecular circumstances of CSC will help us to know the potential therapeutic approach for coping with CSC. A number of researches have been conducted by experts and systematic reviews conducted by Islam 2015 have summarized several therapeutic approaches to CSC.

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Proceedings of The 1stSyiah Kuala International Conference on Medical and Health Sciences May 11-12, 2017, Banda Aceh, Indonesia

Table 2. Therapeutic strategies targeting cancer stem cells 4.

Therapeutic Potential Targets Possible Outcome approach Signalling Notch1,Wnt,Hedgehog,TGF-β, Inhibits cell proliferation and pathways PI3K/Akt/mTORandJAK/ STATetc. increases the sensitivity of CSCs against therapies Cell-surface CD44, CD133, Lrg5, CD26, CD271, Selectively eliminate or killed the molecules CD90 EpCAM etc. CSCs Microenvironment Cytokine network, stroma cells, Interruption of stromal signals immune cells, extracellular matrix, could help to eliminate the CSCs etc. as well as tumour bulk Direct Autologous CSC Selective eradication of CSCs by immunotherapy modified host immune response Preventing EMT Signalling pathways and molecules Inhibit the switching of stemcell involved in,epithelial to like properties of cancer cells and mesenchymal transition such prevent CSC generation asTGF- β, BMI-1etc. Differentiation Switching on metabolic pathways Make the CSCs more sensitive to associated with cell maturation conventional therapies and killed them completely Metabolic Metabolic enzymes and regulators Induce CSCs to differentiated cells pathways like AMP-kinase and make them more sensitive to conventional therapies Side-population Drug transporters Increased sensitivity to Intracellular factors, intracellular Inhibit cell proliferation and self- molecules enzymes such as ALDH renewal Preventing DNA Enzymes and proteins involve in Increased apoptosis and inhibit repair DNA repair cell proliferation Increasing Proteins regulate apoptosis Increased apoptosis apoptosis of CSCs

Conclusion

CSC has a very big role to the mechanism of carcinogenesis. The knowledge of the various molecular markers on cancer stem cells is a key asset for understanding the nature and mechanism of the viability of these cells so that they can serve as guidance on interventions that are useful for treating a cancer. These CSC phenomena become an interesting thing to discuss and require approaches ranging from basic science to clinical management.

References

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Proceedings of The 1stSyiah Kuala International Conference on Medical and Health Sciences May 11-12, 2017, Banda Aceh, Indonesia

4. Islam F, Gopalan V, Smith RA, Lam AK. 2015. Translational potential of cancer stem cells: A review of the detection of cancer stem cells and their roles in cancer recurrence and cancer treatment. Exp Cell Res. 335(1):135-47 5. Li L, Neaves WB. 2006. Normal stem cells and cancer stem cells: the niche matters. Cancer Res. 66(9):4553-7 6. Minguelli JJ., Erice A., Conget PM., 2001. . Exp Biol Med. 226(6):502-7 7. Teoh SL, Das S, 2017. Notch signalling pathways and their importance in the treatment of cancers. Curr Drug Targets. doi: 10.2174/1389450118666170309143419 8. Koury J, Zhong L, Hao J. 2017. Targeting Signaling Pathways in Cancer Stem Cells for Cancer Treatment. Stem Cells Int. doi: 10.1155/2017/2925869. 9. Sinclair A, Latif AL, Holyoake TL. 2013. Targeting survival pathways in chronic myeloid leukaemia stem cells. Br J Pharmacol. 169(8):1693-707. 10. Melzer C, von der Ohe J, Lehnert H, Ungefroren H, Hass R. 2017. Cancer stem cell niche models and contribution by mesenchymal stroma/stem cells. Mol Cancer. 16(1):28 11. Murphy MB, Moncivais K, Caplan AI. 2013. Mesenchymal stem cells: environmentally responsive therapeutics for regenerative medicine. Experimental & Molecular Medicine 45(54):1-7 12. Wei L, Liu TT, Wang HH, Hong HM, Yu AL, Feng HP, Chang WW. 2011. Hsp27 participates in the maintenance of stem cells through regulation of epithelial-mesenchymal transition and nuclear factor-κB. Breast Cancer Res. 13(5):R101. doi: 10.1186/bcr3042 13. Goldstein MG., Li Z. 2009. Heat –shock proteins in infection-mediated inflammation- induced tumorigenesis. J Hematology Oncol 2:5 14. Zorzi E., Bonvini P., 2011. Inducible Hsp70 in the regulation of cancer cell survival: analysis of chaperone induction, expression, and activity. Cancers 3: 3921-3956 15. Fessler E, Dijkgraaf FE, De Sousa E Melo F, Medema JP. 2013. Cancer stem cell dynamics in tumor progression and metastasis: is the microenvironment to blame? Cancer Lett. 341(1):97-104.

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