Cancers are referred to as the aberrant development of cells that infest or spread to other body parts. Colorectal cancer which is the same as colon cancer refers to the growth of cancer from the large intestine. The cancer is generally provoked by lifestyle factors for example smoking, the absence of physical activity and dietary elements, genetic disorders and old age (Xiang et al., 2013). It is considered as one of the most standard cancers as it is gridded as third cancer that results to death in men while the second in women. Colorectal cancer is either benign meaning it doesn’t pose vital health threats or malignant which means it can cause crucial health threats and propagate to the rest body parts. Thus. Proper immunotherapy strategies are required to ensure patients with advanced colon cancer get treatment.
In this particular case of colorectal cancer, the inducement of a dendritic cell is the prudent strategy of immunotherapy of cancer. Dendritic cell refers to a cell that is potent and antigen and is central to the inducement of antitumor immune reactions. Combining both the instigation of dendritic cell and immune-modulating principles is the best shot at increasing antitumor immunity for colorectal cancer patients. Surgeries specifically adjuvant chemotherapy and neoadjuvant radiotherapy are also applicable as a curative treatment for this cancer (Kajihara et al., 2016) . However, 20% of patients suffering from colorectal cancer are not eligible for surgery for reasons such as liver metastases during diagnosis hence 50% of patients die due to the metastatic ailment.
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Previous studies conducted propose that colorectal cancer is perfect for immunotherapy. Colon cancer display varieties of tumor-related antigens, for instance, carcinoembryonic antigen and mucin 1. The cancer is known as a heterogeneous sickness that has not only genetic profiling but also epigenetic which means it develops through differentiation of an unstructured egg. These characterizations concerned with colorectal cancer include CpG island methylator phenotype, chromosomal instability pathway, microsatellite instability, DNA hypomethylation, and mutation of oncogenes (Kajihara et al., 2016) . The defaults reflected by these epigenetic and genetic attributes of cancer, for instance, the microsatellite instability showcases several inadequacies in the DNA mismatch-repair system that consequently lead to a rise of the mutation of oncogenes.
Chromosomal instability pathway displays chromosomal and aneuploidy rearrangements while on the other hand CpG island methylator demonstrates DNA methylation related to the deactivation of tumor-suppressor genes. It is therefore correct to say that these defaults cause immunogenic colorectal cancer, which means that some of the patients suffering from this cancer are prone to immunotherapy (Kajihara et al., 2016) . Immunotherapy links up a strong anti-tumor effect with chemotherapy or radiotherapy. For patients with colorectal cancer combining chemotherapy, radiotherapy and immune checkpoint blockade agents to infer efficient and effective antitumor immunity.
Regarding the antitumor immunity, T cell receptor cells indicate CD4 or CD8. The CD4 are known as helpers whereas CD8 are cytotoxic subsets. CD8 deduce class 1 molecules on cancer cells likely to have peptide while CD4 cells acknowledge complex class II molecules found in antigen-presenting cells (Koido et al., 2013). The major aim of cancer immunotherapy is to ensure there is an efficient introduction of antigen-specific cytotoxic CD8 cells. The induction of these T cells requires the help of CD4 cells which generate cytokines like interferon and interleukin. The function of these cytokines is to maintain the CD8 cells which not only reacts to antigenic peptides found in class 1 molecules present in cancer cells but also eliminate tumor-associated antigens in cancer cells.
Dendritic cells are significant as they have a central role in controlling, initiating and programming antitumor immune responses. They control and process antigens which eventually causes the production of IL-12. There also these antigens are transformed to complex antigenic peptides and class II molecules. They are then presented by dendritic cells in the lymph node causing the activation of both the T cells that are CD8 and CD4 cells. Furthermore, the bonding between the dendritic cells and immune cells that are either innate or innate-like ensures efficient introduction of antitumor immunity. PD-1 refers to a T cell immunity check that causes cell tolerance during T cell activation causing cells with PD-L1 and PD-L2 immune (Patel & Kurzrock, 2015). Despite all this colorectal cancer proved to respond poorly to PD-L1 in clinical settings (Xiao & Freeman, 2015). Some examples of these immune cells include invariant natural killer, T cells and a natural killer. They can attack tumor cells directly and efficiently.
Immunotherapy designed for cancers, for instance, adopted cell transfer therapy, peptides, and whole tumor cell vaccines and viral vector vaccines are applicable to treat patients with colorectal cancer. Thus, dendritic cells contain various antigenic peptides, for example, whole-tumor derived apoptotic bodies, whole tumor cell lysates and whole tumor cell- mRNA. The combination of these cells form the dendritic cells tumor fusions which produce a wide array of tumor-associated antigens that introduce molecules of class I and II as co-stimulatory molecules (Kajihara et al., 2016) . Cancer cells tend to evade immune surveillance using various mechanisms. The first mechanism they use is the translation of immune checkpoint blockade between the CD8-T cells and tumor cells.
The activation of these T-cells is managed via immune suppressive cell populations around the tumor environment enabling eluding from the immune surveillance. The second mechanism employed by cancer cells is the dysfunction of the dendritic cells which are necessary for the detection of cancer cells in patients suffering from colorectal cancer (Kajihara et al., 2016) . Other mechanisms used by cancer cells for hibernation are; the manufacture of various immune suppressive factors by tumor cells, availability of immunosuppressive cells like immunosuppressive tumor-associated macrophages and tolerogenic dendritic cells, the regulation and control of antigens such as TAP 1/2, presence of immunosuppressive cells and the inducement of regulatory T cells which produce immunosuppressive and proinflammatory cytokines like IL-10 to mention but a few.
Therefore, the dendritic cells-based immunotherapy for cancer is used to treat colorectal cancer through inducing tumor-associated antigens like DNA and whole tumor cells which manufacture the response of T-cells specifically CD4 and CD8. The immunotherapy can either use the allogenic tumor cell lines or the autologous tumor cells for the induction of antitumor immunity. The mRNA transfected dendritic cells are more potent especially concerning the propagation of antitumor immunity to patients suffering from colorectal cancer (Kajihara et al., 2016) . Regarding the fusion of dendritic cells and whole tumor cells produces a heterokaryon molecule that presents antigenic peptides and polyclonal antigens.
In these tumor fusion cells, tumor-associated antigens advance endogenous antigen-processing pathway. Another mechanism that is used to treat patients of colorectal cancer is the use of autologous whole tumor cell lysates which are to produce the tumor-associated antigens. These dendritic cells which are packed with whole tumor cell lysates simultaneously ensure CD4 and CD8 cells are activated. The activation of these T-cells provides ample help for the maintenance and inducement of CD8+ cytotoxic T lymphocyte-associated antigens. The use of autologous T-cells expresses high synergism that ensures colorectal cancer patients are treated. DNA mismatch repair is another cancer therapy used on colorectal cancer (Kajihara et al., 2016) . It refers to a group of genes that play a vital role especially correcting and regulating genomic stability. These genes are encoded with four proteins.
For instance, the WT1 gene contains oncogenic attributes like tumor progression, distant metastasis and also lymph node metastasis making the antigen very promising concerning immunotherapy of colorectal cancer. Due to its essential ability to regulate and maintain cancer cells characteristics. MAGE is also another antigen for cancer found in human malignancies developed as an immunotherapy strategy for patients with colorectal cancer (Kajihara et al., 2016) . Therefore, the treatment of colorectal cancer depends on various factors like the health status of patient, stage, spread, and location of cancer. The available treatment options for colorectal cancer are surgery, chemotherapy, and radiotherapy (Koido et al., 2013). Chemotherapy uses either chemical or medicine to annihilate cancer cells. Radiotherapy uses high-intensity radiations to damage and curbs the cancer cells from multiplication.
References
Kajihara, M., Takakura, K., Kanai, T., Ito, Z., Saito, K., & Takami, S. et al. (2016). Dendritic cell-based cancer immunotherapy for colorectal cancer. World Journal of Gastroenterology , 22 (17), 4275. doi: 10.3748/wjg.v22.i17.4275
Koido, S., Ohkusa, T., Homma, S., Namiki, Y., Takakura, K., Saito, K., & Arihiro, S. (2013). Immunotherapy for colorectal cancer. World journal of gastroenterology: WJG , 19 (46), 8531.
Patel, S. P., & Kurzrock, R. (2015). PD-L1 expression as a predictive biomarker in cancer immunotherapy. Molecular cancer therapeutics , 14 (4), 847-856.
Xiang, B., Snook, A. E., Magee, M. S., & Waldman, S. A. (2013). Colorectal cancer immunotherapy. Discovery medicine , 15 (84), 301.
Xiao, Y., & Freeman, G. J. (2015). The microsatellite instable subset of colorectal cancer is a particularly good candidate for checkpoint blockade immunotherapy. Cancer discovery , 5 (1), 16-18.
