The 5-year survival rate for individuals diagnosed with localised renal carcinoma was approximately 93% between 2008 and 2014. However, for individuals with mRCC, the survival rate decreased to 12%[33]. The emergence of targeted therapy has raised the survival rate of RCC patients, although the 5-year survival rate of patients with mRCC remains quite low, especially for individuals with poor prognostic factors[34]. Interleukin-2 (IL-2) and interferon α (IFN- α) Cytokine therapy, represented by, has displayed some benefits in a small number of patients with advanced RCC (aRCC), but it has only proved effective in a limited proportion of patients[35]. In addition, cytokine therapy is associated with high toxicity levels, limiting its general use[36]. Now the immunotherapy of mRCC has developed from cytokine to checkpoint inhibitor. It targets immunosuppressive checkpoints, containing programmed cell death-1 (PD-1) receptor, programmed cell death ligand-1 (PD-L1), and cytotoxic T lymphocyte associated protein 4 (CTLA-4)[37]. There were just a few people who had an objective response to checkpoint inhibitors; others had delayed response; and many people saw no theraputic benefits[38, 39]. There are a number of concepts that attempt to explain why checkpoint inhibitor medication may not be effective in some patients. Its expression may be related to the pathogenesis and mechanism of renal tumors. This is because in renal tumors, there are a variety of etiologies, the gene and cellular composition of the microenvironment surrounding the tumor have an effect on the number, function, and localization of immune effector cells, thus it is possible that this has a significant bearing on the body's response to checkpoint inhibitors[40].
Cell senescence represents one of the most crucial risk factors for cancer patients. Although the close relationship between cell senescence and the tumor development has become evident, the changes related to cell ageing in the renal tumor microenvironment still remain elusive[41]. The progress of sequencing technology and bioinformatics tools makes it possible to describe the changes related to cell senescence and renal tumor microenvironment. In this study, we comprehensively evaluated the characteristics of immune infiltration and the microenvironment of ccRCC induced by cell senescence, and analyzed and verified the efficacy of immunotherapy in ccRCC induced by cell senescence.
This study screened 37 ageing genes significantly related to prognosis in ccRCC. Also, lasso regression analysis depicted that 17 of them were more suitable for constructing the prognosis model. Furthermore, the KM survival analysis of the model's high-risk and low-risk groups reveals that TCGA and GEO data samples have significant differences in OS, and the ROC curve results further show that the model provides accurate and dependable results. Furthermore, age was found to be an independent prognostic factor for ccRCC by univariate and multivariate Cox regression analyses, suggesting a close link among ageing and cancer progression, which is consistent with previous research results[41, 42]. To further evaluate whether the constructed model applies to patients of various clinical stages, we analysed the survival rate of the early and late high-risk groups, which revealed results consistent with the our expectations.
Gene enrichment analysis demonstrated that adipocytokines, cytokines and receptors, ErbB, hematopoietic cell lineage and immunity were active in high-risk group. Recent research has demonstrated that certain hormones derived from adipose tissue may have a major impact on the growth and proliferation of tumor stroma and internal malignant cells[43]. All immunological responses involve cytokines in multiple intricate ways. Cytokine interactions are comprised of intricate and interrelated positive and negative feedback systems that provide homeostasis and immune regulation[44]. Age-related immune response alters in the hematopoietic system due to decreased hematopoietic stem cell function, which ultimately contribute to increased susceptibility to infection, autoimmunity, anemia, and myeloproliferative diseases[45]. ErbB receptors are overexpressed or mutated in many cancers; and its overexpression and over-activation are associated with poor prognosis, drug resistance, cancer metastasis and low survival[46]. The human immune system is responsible for identifying self and non-self to protect the body from exogenous and endogenous diseases. In addition, the immune system recognizes many threats and eliminates them in order to maintain homeostasis[47]. The primary immunodeficiency and tight junction pathway were significant in the low-risk group. Congenital genetic defects or dysfunction of one or other immune system components may disturb the complex physiological balance and functional bodily homeostasis, thus reducing its preventive ability and even actively promoting the formation of tumor diseases[48]. Disturbance of the expression, function, or disruption of tight junction protein integrity are associated with various diseases, including skin, intestinal and lung diseases, as well as various forms of cancers[49]. However, greater number of studies are required to elucidate the mechanistic links between cancer and cell senescence.
This study concluded that the tumor mutation load of the high-risk group was higher, while the survival rate of the group with high tumor mutation was lower. Because chemokines, growth factors, regulatory factors, proteases and regulators, soluble or exfoliative receptors or ligands, as well as Interleukins are crucial for the regulation of cancer cells and immune cells, they are able to enhance cytotoxicity and play a wide range of anti-tumor activities. Therefore, this study investigated the differential gene expression of high- and low-risk groups in these aspects, which can be used for further immunotherapy studies. Cellular immunotherapy is a novel form of tumor therapy that has a remarkable curative effect. It is a novel type of anti-cancer autoimmune therapy. Therefore, this study evaluated the association between immune cells and patient risk scores, and analyzed the immune checkpoints on immune cells. The results also demonstrated the differential expression of model genes at different immune checkpoints in high and low-risk groups. These results have a strong guiding significance for future research.
Immunotherapy was found to have no significant effect on high-risk or low-risk groups despite significant differences in tumor mutation load, immune cell infiltration expression, and the differential expression of immune checkpoints. IMvigor database verification results were consistent with this study's results. Therefore, despite the advantages of immune checkpoints, the overall effect of immunity will be affected by the different genetic composition of tumors and the cellular composition of tumor microenvironment in different etiological types[33]. The mechanism of ICI drug resistance can be primary or congenital, or secondary or acquired[50]. They include the abnormal expression of MHC class I molecules and the expression of immunosuppressive cytokines. In addition to the above two possible mechanisms, regulatory T cells (Tregs), regulatory B cells (Bregs), myelogenous suppressor cells (MDSCs), and tumor-associated macrophages (TAMs) are all capable of inducing an immunosuppressive response throughout the process of tumor immune escape. However, the immune escape pathways mediated by Tregs, Bregs, MDSCs and TAMs have not been thoroughly studied. related research focuses mostly on the substances provided by immunosuppressive cells that can cause immunological escape and perform an immunosuppressive effect, as well as their signal transduction pathways and the interaction between immunosuppressive cells and other immune cells[51]. Our study reveals that through enhancing sugar chains and glycosylation, tumor cells may be able to evade anti-tumor immunity and even contribute to regulating immune cell activity to enhance tumor growth[52]. This will become a new field in the near future.
Finally, based on drug screening analysis of the differences of risk pertaining to the genes, this study identified 6 drugs that can significantly reduce gene expression in high-risk groups. Enzastaurin is a selective inhibitor of protein kinase C β Active new oral anti-tumor drugs, used to treat solid cancer and blood cancer, participate in the active AKT and MAPK signalling pathways in many cancers[53]. Voreoxin, an anticancer quinolone derivative, has shown strong activity in tumor models in vivo and in vitro[54]. BIIB-021 is a synthetic HSP90 inhibitor, and the overexpression of HSP90 is a factor in tumor development. Monotherapy with HSP90 inhibitors has achieved some success[55]. ZM447,439 (ZM) is an auroral selective ATP competitive inhibitor, which interferes with spindle integrity checkpoint and chromosome separation. Studies have confirmed that laser kinase is a potential molecular target of ZM for cancer treatment[56]. Lovastatin has a significant inhibitory effect on the activity of cancer cells in a variety of cancers (such as breast cancer, liver cancer, cervical cancer, lung cancer and colon cancer). At the same time, Lovastatin has been shown to also increase the sensitivity of some types of cancer cells to chemotherapy drugs and enhance their therapeutic effect[57]. Tryprostinil is an EP2 receptor agonist; EP2 receptor activation engages β-arrestin in a G-protein-independent pathway that promotes tumor cell growth and migration[58].
Notably, this study has several limitations. First, these survival related cross genes were identified from the TCGA database, where patients were mainly white or American. Considering the genetic heterogeneity, these cross genes need to be verified in more databases. Secondly, this study lacks in vivo and in vitro experiments to further verify the risk difference of genes and selected drugs. Finally, this study did not further study the possible mechanism of immune escape.