Infiltration, metastasis-related molecules
1.Epidermal growth factor
Epidermal growth factor (EGFR) is a peptide that regulates cell growth and has tyrosine kinase activity. EGFR receptor is a phosphoglycoprotein with a molecular weight of 170 kD, mosaic on the cell membrane, and is the expression product of the proto-oncogene C-erbB-1, which can effectively bind to EGF and TGFa to promote the proliferation of epithelial cells and is closely related to cell malignancy [120]. The Steele study concluded that high levels of EGFR receptor expression in colorectal cancer were associated with poor prognosis. In China, Wang Lixia et al [121] also reported that the survival of colorectal cancer patients was negatively correlated with the expression rate of EGFR in tumor tissues, which could be used as a predictor of prognosis. Although the monoclonal antibody C225, which competitively binds EGFR, has been used for clinical treatment, the prognostic significance of EGFR also needs to accumulate more information.
2.Vascular endothelial growth factor
The growth and metastasis of solid tumors require neovascularization, and tumor angiogenesis is regulated by angiogenic factors secreted by tumor cells, among which vascular endothelial growth factor (VEGF) is a new tumor vascular regulator recently discovered.
VEGF expression is associated with infiltrative metastasis in colorectal cancer. a study by Takahashi et al [122] on colon cancer concluded that MVC was significantly higher in those positive for VEGF expression than in those negative for VEGF expression. Also at the leading edge of cancer infiltration, the higher the density of microvessels and the more pronounced the neovascularization, the more pronounced the expression of VEGF, showing the consistency of VEGF expression with the site of neovascularization, indicating that VEGF expression is associated with infiltrative growth. Studies have shown that the prognosis of colorectal cancer patients with positive VEGF expression is significantly worse than that of VEGF-negative ones, reflecting the biology of colorectal cancer and being a meaningful prognostic indicator [123, 124]. The molecular target drug Avastin for it is already in clinical use.
3.Microvascular density (MVD)
MVD is associated with lymphatic vascular infiltration around the tumor, which can predict high density of microvessels to increase tumor cell shedding and metastasis to distant sites via peripheral vessels and lymphatic vessels. The status of surgically resected lymph nodes in colorectal cancer has been its most important prognostic factor. However, the presence or absence of lymph node metastasis alone cannot explain all the differences in colorectal cancer prognosis; in fact, approximately 25% of patients with negative lymph nodes will still develop recurrence or metastasis. Negative or positive lymph nodes do not accurately assess the risk of recurrence or metastasis after colorectal cancer surgery. Recently, MVD has been reported as a prognostic indicator for colorectal cancer [125, 126]. In early stage colorectal cancer with negative lymph nodes, MVD can be used to select patients with potential metastasis or high risk of metastasis for postoperative systemic adjuvant therapy so that they can benefit.
4. Matrix metalloproteinases and inhibitory factors
Matrix metalloproteinases (MMPS) are a group of matrix-degrading enzymes that play an important role in tumor infiltration and metastasis. TIMPS are a class of metastasis inhibitory factors divided into four categories, namely TIMP1, TIMP2, TIMP3 and TIMP4. Murray et al [127] studied 64 cases of colorectal cancer and found that MMP-1 (collagenase) was present in tumor cells, and positive patients tended to have a poor prognosis and were not associated with stage. Patients with positive tumor MMP-9 protein have been reported to have a poorer prognosis, also independent of stage [128, 129]. A domestic study [130] concluded that MMP-2 expression was positively correlated with lymph node metastasis and distant organ metastasis, which is consistent with the study of Baker et al [131].
5. Urokinase-type fibrinogen activator and inhibitor
Urokinase-type plasm inogen activator (uPA) is a serine protease that catalyzes the conversion of fibrinogen into fibrin, which then degrades a variety of extracellular matrix components and also promotes MMP-2 activation fibrinogen activator inhibition (PAI) to counteract its effects. uPA is another class of metastasis inhibitors. It is generally believed that the more uPA immunohistochemistry positive cells in the tumor, the worse the prognosis; high PA I-2 level is good prognosis.
6.E-calcineurin
E-cadherin is a Ca2+-dependent adhesion molecule that mediates cell-to-cell adhesion. E-cadherin is a transmembrane protein, and its cytoplasmic part interacts with intracellular proteins, especially β-catenin, to maintain normal cell function. The loss of E-calcineurin and increased infiltration of tumor cells is one of the changes. It is mostly believed that low E-calcineurin expression is associated with poor prognosis [103, 130].
7. nm23
is a tumor metastasis suppressor gene, localized at 17q21.3, encoding human nucleoside diphosphate kinase (NDPK). normal expression of nm 23 gene not only inhibits tumor cell infiltration and metastasis, but also indirectly inhibits tumor formation; loss or mutation of nm 23 allele is associated with colorectal cancer metastasis. yamaguch et al [132] cited that nm 23 gene abnormal expression is closely related to colorectal metastasis in situ. In China, Qin Zike et al [133] reported that with the decrease of nm23 protein expression in colorectal cancer patients, tumor cells deteriorated and caused infiltration and metastasis, and the prognosis was correspondingly poor.
Cancer cell antigen expression
1. carcinoembryonic antigen (CEA)
Among the antigens expressed by colorectal cancer, CEA is the most clearly studied. There are four forms of CEA distribution in cancer tissues detected by immunohistochemical methods: ① type A, CEA is distributed on the surface of cancer cells; ② type C1, CEA is distributed in the cytoplasm with cell polarity; ③ type C2, diffusely distributed in the cytoplasm, independent of cell polarity; ④ type S, CEA is located in the stroma surrounding cancer cells. Some authors also refer to type A as the luminal margin type, type C1 as the cytoplasmic type, and types C2 and S as the diffuse type. In highly and moderately differentiated cancer tissues, type A and C1 are predominant. type C2 correlates with the degree of moderate differentiation, whereas moderately and poorly differentiated carcinomas, especially those with low differentiation, are predominantly type S. Although the forms of CEA distribution in cancer tissues with different degrees of differentiation crossed, the distribution sites of CEA were closely related to the degree of differentiation of cancer cells.
It is generally believed that the mode and intensity of CEA expression in tissues are important indicators reflecting the clinical biological characteristics of colorectal cancer: the stronger the CEA expression and the more diffuse the distribution mode, the lower the pathological differentiation, the deeper the infiltration into the intestinal wall, the higher the rate of lymph node metastasis and the recurrence rate of metastasis after surgery, the shorter the survival period and the poor prognosis. Preoperative positive blood CEA and diffuse strong positive tissue CEA expression indicate a worse prognosis, and this patient should be intensively treated and followed up with adjuvant therapy.
Meanwhile, the expression of CEA correlates with Dukes stage and DNA ploidy of cancer cell nuclei, and the expression of CEA in aneuploid cancer tissues is significantly higher than that in diploid cancer tissues, especially in Dukes C and D stages, which reflects the correlation between CEA and prognosis from the side.
2.Blood group antigen
Many studies have confirmed the lack of expression of blood group ABH antigens in the distal colon and rectal mucosa, whereas these antigens are present in tumors at these sites.ABH antigens are present in neoplastic (adenocarcinoma) polyps rather than hyperplastic polyps. Many of the tumor-associated antigens identified by monoclonal antibodies are variant blood group glycolipids, and the variant Lewis antigens represent another group of embryonic antigens associated with colorectal cancer.
3. Monoclonal antibody-labeled antigens
Koprowski et al. discovered the monoclonal antibody 17-lA. input this antibody can cause immunosuppression of cell growth. Johnson et al. applied monoclonal antibody B72.3 found a macromolecular glycoprotein (TAG-72). Although this antigen is expressed in 85% of colorectal cancers, there is still considerable variation in the expression in primary foci, lymph nodes and distant metastases.
4.Tn antigen
The mucin secreted by normal intestinal mucosa epithelium and its tumor is a high molecular glycoprotein with diverse carbohydrate chains. these oligosaccharide chains are of different lengths, but they are all linked to serine or threonine of mucus polypeptide, forming GaINAc–O-Serlthr structure, called Tn antigen. the Tn antigen increases specific sugar molecules under the control of glycosyltransferase, further glycosylation, and then increase salivary acid, forming Sialosyl-Tn antigen (Sia2,6GaINAc2-O-Ser/thr) – tumor-associated antigen.Itzkowitz reported [134] that 87.5% of colorectal cancers express Sialosyl-Tn antigen, and it is independent of age, sex, race, site of occurrence , Dukes’ stage, depth of infiltration, degree of differentiation, and ploidy, and the 5-year survival rates were 100% and 73% for Sialosyl-Tn antigen negative and positive, respectively (P < 0.05). Multiple regression analysis showed that Sialosyl-Tn antigen expression and tumor ploidy were the two most important predictors of recurrence and prognosis. Therefore, Sialosyl-Tn antigen was considered as an independent predictor of prognosis in colorectal cancer patients.
Telomerase activity
Alterations in telomerase activity and telomerase length have been widely used clinically in the diagnosis and prognosis estimation of various malignancies.Tatsumoto et al [135] observed telomerase activity and length in 100 colorectal cancer and 100 colonic mucosal specimens with noncancerous lesions, which were followed up for 3 years after surgery.96 of the 100 colorectal cancer specimens had telomerase activity. Since measurable telomerase activity was also present in colonic mucosal specimens from noncancerous lesions, telomerase activity levels were divided into three groups: the high-activity group was 50-fold greater than the noncancerous lesion group; the moderate-activity group was 10 to 50-fold; and the low-activity group was less than 10-fold greater than the noncancerous group. Among 100 cancerous tissues, 28 showed moderate activity and 44 showed high activity. Patients with high activity telomerase had a significantly worse prognosis than the moderate and low activity groups. Disease-free survival was also significantly lower in patients with high telomerase activity in 87 patients undergoing radical surgery, supporting the possibility that telomerase activity may be one of the independent prognostic indicators for patients with colorectal cancer.
Shoji [136] examined telomerase activity (TA) in 30 colorectal cancer specimens and 30 corresponding normal colorectal mucosa. The telomerase index is expressed as TI, which is defined as TI = log(A-B). a represents telomerase activity in cancerous tissue and b represents telomerase activity in normal mucosa, which is significantly higher in cancerous tissue than in normal mucosa. ti is closely related to the depth of tumor invasion, but not to age, sex, tissue type, site, lymph node metastasis, lymphatic infiltration, or Dukes stage. There was no correlation. There was a significant difference between TI with and without venous invasion. 4 out of 5 cases of liver metastases had elevated TI, suggesting that high TI may be a risk factor for liver metastases from colorectal cancer.
Microsatellite instability
Microsatellite instability (MSI) is associated with mutations or loss of the MMR gene.MSI is associated with almost all hereditary nonpolyposis colorectal cancer (HNPCC) and 13% of sporadic colorectal cancers [137]. Relatively MSI(+) colorectal cancers are more likely to occur in the proximal colon, with pathology that is mostly mucinous and poorly differentiated, but often with wild-type p53 expression and a better prognosis [138].Gryfe et al [139] studied 607 colorectal cancer patients and suggested that although MSI(+) is associated with a low-grade pathological type, it can suggest a better prognosis independently of other prognostic indicators, and reduced local lymph nodes and the risk of distant metastases, with 5-year survival rates of 76% and 54% for MSI(+) and MSI(-), respectively. The sensitivity of MSI(+) advanced colorectal cancer to irinotecan chemotherapy has been reported, suggesting the value of MSI in determining the prognosis of colorectal cancer [140].
Survivin
Survivin is a newly discovered inhibition apoptosis protein (IAP) with a 15 kb gene located at 17q 25, containing four exons and three introns, and encoding a protein containing 142 amino acids, which is currently the most studied gene in the family of human IAPs. Survivin is not expressed in normal mature tissues, but is widely expressed in the most common human tumors, including hepatocellular carcinoma, lung cancer, colon cancer, pancreatic cancer, prostate cancer, and breast cancer. It was concluded that high expression of Survivin is associated with recurrence and metastasis of colorectal cancer, and its expression status is an independent prognostic factor after radical colorectal cancer surgery and a valuable indicator for prognosis determination of colorectal cancer patients [141-143]. Meanwhile, if inhibiting Survivin expression or function in tumor cells can induce spontaneous apoptosis of tumor cells [144]. Current research is working on screening effective Survivin inhibitors, such as antisense oligonucleotides targeting Survivin, RNA interferers and some small molecule compounds, which can increase chemotherapy sensitivity while killing tumor cells may also increase the effect of chemotherapeutic drugs [145].Survivin can be an ideal gene therapy and immunotherapy for colorectal cancer molecular targets.