Cancer is a disease that is growing at a fast rate. Not only is the United States suffering from it but the world entirely is being impacted. The discovery for the cure of cancer has been ongoing and the medical field has been unsuccessful. Treatments vary from chemotherapy to surgical procedures but a key component to increase success in treating cancer is combining the existing treatments to ultimately have a stronger and more efficient treatment that will help cancer patients.
The Benefits of Tumor Suppressor Genes for Cancer Treatments
Cancer is a general name that describes an overall disease, within cancer there are branches of malignancies that affect different areas of the body. Along with the different types of cancer there are treatments that exist; these treatments are fit for specific cancers and they will be more successful in different cancers. One treatment will not cure all cancers. Breast, colon, rectum, lung, melanoma, prostate, and thyroid are prevalent cancers from 2016 to today (American Cancer Society,2016). Common treatments are chemotherapy, surgical procedures, radiation, hormonal therapy, immune therapy, and gene therapy. Treatments like chemotherapy and radiation are successful but they have immense side effects. Possible side effects are anemia, bleeding, fatigue, bowel dysfunction, low bone density, and/or heart damage. The development of treatments is ongoing but yet cancer is still the second most common cause of death (Jiang et al., 2011). Treatments can be intense and detrimental to the human body. To decrease the negative side effects treatments can be combined to potentially provide a more efficient treatment for the patient. Gene therapy is the use of a specific gene’s, in this case tumor suppressor gene p53, contributes its genetic material to help restore abnormal cells. The combination of gene therapy with other cancer treatments is becoming more common, it has been proved to be beneficial and to be less harmful than using single treatments alone. Combination therapy has been a promising path to take to attack tumor genetic mechanisms (Jiang et al., 2011).
The p53 gene is plays a role in regulating cell death through apoptosis. It is a gene known as a tumor suppressor. Its functions help treatments have higher success rates. The functions of p53 can provide many benefits to existing treatments. Wild-type p53 can inhibit the tumor vascular endothelial growth factor (VEGF) expression and prevents carcinoma (Yu et al., 2014). The inclusion of the recombinant human adenovirus p53 gene in chemotherapy helps improve treatment with the following mechanism, it retrains tumor growth through cell cycle arrest and begins cell death, it helps enhance the apoptosis and cell cycle arrest caused by chemo, helps produce anti-tumor immune responses and uses ‘bystander effect’ to induce tumor necrosis ( Xiao et al., 2017).
Chemotherapy damages cells allowing for tumor cells to override apoptosis and eventually making the treatment unsuccessful in the long run (Jiang et al., 2011). A small scale study was conducted on patients who suffered from cervical cancer. The population studied was divided in two groups, one group was receiving chemotherapy while the other was receiving chemotherapy and recombinant human adenovirus – p53 (rhAd-p53) solution 1 X1012 VP injection for three days for three times a day. After the chemotherapy ended results were analyzed. The PVP group (group only receiving chemo) had a tumor reduction of 11.42±2.78 cm2 and the combined treatment group had a tumor shrinkage of 15.25±4.00 cm2 (Xiao et al., 2017). The measurements showed that combined chemotherapy had a significant increase of success compared to a patient only receiving chemotherapy. The side effects were recorded and overall less patients in the combined group suffered from gastrointestinal discomfort, bone marrow suppression, and elevated aminotransferase levels. Results show significant benefits of combining treatments and another possible for is combining gene therapy with oncolytic virotherapy.
Oncolytic virus (OV) therapy uses a weak form of a virus to attack and kill cancer cells. Throughout this procedure the oncolytic virus grows not only in the cancer cells but sometimes spreads to healthy cells. Ultimately the OV kills the infected cell but it can be harmful to the properly functioning cells (Bressy et al.,2017). Combining the p53 gene with OV therapy helps resolve this problem stimulating apoptosis in the infected cells. SG600-p53 gene is a replicative adenovirus that can selectively replicate in tumor cells. The p53 transgene was injected between E1a and E1b genes allowing for this new location to help stop the gene from attacking the oncolytic virus (Bressy et al., 2017). Combining these two therapies allow for the virus to attack only the infected cells not the healthy cells, this reduces side effects of OV therapy. Cancer treatments are already helping many survive but combining treatments will improve results and help eliminate deficiencies that one treatment may result in.
Gene therapy is a progressive treatment for cancer and it has been an important discovery that has helped decrease side effects for existing cancer treatments, but a future area of research could be the long-term effects of the gene p53. The tumor suppressor, p53, is beneficial when paired with existing cancer methods, but many ask what negative impacts may be caused by adding a modified tumor suppressor to a body that is not used to having more than one. Viral vectors are under research to decrease possible toxicity caused by the injection of p53 gene (Roth and Cristiano, 1997). Despite the success of gene therapy it is important to continue the investigation of possible toxicity and finding the solution to prevent it will bring us a more successful treatment that will not continue to hurt a cancer patient.
