**10. Conclusions**

*Basic Principles and Practice in Surgery*

cancer patients [65].

remains unclear.

represented [69].

sion and metastasis.

**8. Lgr5**

**7. CD29**

overexpression of CD166 failed to predict its outcome. Some literature studies found a worse overall survival in colon cancer cases characterized by high CD166 expression [64]. Levin et al. found that even the survival was reduced by 15 months for patients who presented colon tumors characterized by high CD166 expression compared with tumors with low or absent CD166 expression [67]. Other studies could not establish the prognostic relation of CD166 in colon

Limited number of studies analyzed CD166 expression in colon cancer patients, and existing results are inconclusive. Therefore, the role of CD166 in colon cancer

Through CD29 molecule, also known as integrin β1, cells adhere to extracellular compartment proteins and facilitate intracellular transmission of the cellular signal [68]. CD29 presents with 3 structural domains, the extracellular one being best

Expression of CD29 was observed in normal and tumor colonic tissues, and a presumptive role in cellular differentiation was attributed to it, due to the activation of Erk signaling pathway [68, 69]. In normal colonic mucosa, CD29 is expressed in the lower part of the intestinal crypt [69] and is considered to be involved in intestinal proliferation [68]. However, its precise role in colon cancer is unknown [68]. At present, CD29 expression in colon cancer is only used as diagnostic marker for CSCs. Further studies are needed to evaluate its involvement in cancer progres-

Leucine-rich repeat-containing G-protein coupled receptor 5 or Gpr49 is a receptor formed by eight main domains [69]. Lgr5 was identified on the cellular surface of intestinal and colonic stem cells and is being considered thus a biomarker of them [70]. Lgr5 overexpression was also confirmed in esophageal and colon

Lgr5 is expressed in both normal and tumor colonic tissues [69]. In normal colon tissue, Lgr5 is expressed in a small area of the intestinal crypts. Its expression area increases with cell transformation in adenoma and is most elevated in colon adenocarcinoma [69]. The percentage of colon cancer patients expressing Lgr5 is,

Overexpression of Lgr5 in colon cancer correlates with advanced stages of the disease [70, 71], with lymph node involvement (L) [70, 71] and perineural invasion [71] and distant metastases (M) [70]. Lgr5 involvement in cellular proliferation is also suggested due to the correlation found between Lgr5 expression and Ki-67 expression [70]. Lgr5 is thus considered to have a role in colon cancer development and progression and possibly in liver metastases formation as well [69]. Moreover, Lgr5 is considered to have a clinical role in predicting advanced pathological stages of colon cancer tumors [72].

Aldehyde dehydrogenase 1 is a detoxifying enzyme involved in colon cancer proliferation [73]. Expressed in low percentage in normal colonic mucosa, ALDH1

cancer, in hepatocellular carcinoma, and in ovarian cancer [70].

according to literature studies, around 80% [70, 71].

**14**

**9. ALDH1**

Colon cancer stem cells (CCSCs) could be responsible for tumor metastases, resistance to chemotherapy, and recurrence, and their identification is thus of major importance. However, the amount of biomarkers identified at the cellular surface of CCSC failed to become valuable prognostic markers, and further studies are necessary to evaluate their role in cancer progression and distant metastases formation.
