Peripheral T-cell lymphoma is an aggressively lymphoproliferative disease that seriously threatens human health, most patients with PTCLs have a poor prognosis due to the combination of the lack of specific treatment and an aggressive clinical process[20]. however, molecular risk stratification which based on gene expression profile (GEP) into some type of human cancer has opened an avenue for clinicians to personalized medicine and brought enthusiasm for researchers to applicate to other cancer types[21].until recently, PTCLs was lagged behind in terms of risk classification unfortunately. In the present research, we developed a prognostic signature that based on six genes (DOCK2, GSTM1, H2AFY, KCNAB2, LAPTM5 and SYK) for PTCLs and validated it in internal test data sets. Complementary value of clinical characteristics and molecular were further leveraged and showed that combination of both could accurately predict the overall survival of PTCLs.
There is an increasing application of risk signature used for predicting prognosis of cancer patients due to the carcinogenesis and development of tumors are the interaction of multiple genes[21, 22]. On the other hand, the risk signature based on multigenes usually shows better performance in predicting the prognostic value than an individual gene or clinical characteristic risk classifier[23]. Therefore, in our study, we built a multi-mRNA-based signature with the LASSO Cox regression model to predict overall survival of PTCLs, and the prognostic and predictive accuracy of this signature was assessed in train group and test in internal testing patient groups. By utilizing this mRNA signature to the PTCLs patients, significantly statistical difference was depicted in the survival curve between high risk group and low risk group. Compared with wen yin's report of 5 genes signature predicting the survival of Glioblastoma multiforme and jie zhu’s research of 6 genes signature discriminating the high risk and low risk group of lung cancer[24, 25], our signature classifier show better performance. Additionally, our six-mRNA signature is an independent prognostic factor which has been corroborated by the univariate and multivariate cox analyses. Moreover, to accurately predict the outcome of each individual PTCLs patient, we combine clinical characteristics and 6-mRNA signature to construct nomograms, and we had evaluated the calibration of the nomogram according to the calibration curve. In our study, The c-index for the nomogram in train group and test group patient was 0.765, and 0.688 respectively (3-, 5-year OS),significantly higher than previous research that used to predict the prognosis of non-small cell lung cancer patients[26], showing that there is distinguished consistency between predicted survival probability and actual survival proportion, and indicating our nomogram that based on the six genes signature is a promising tool for predicting the outcome of PTCLs patients and can be useful for clinicians to implement personalized treatment.
In this context, all genes except H2AFY and KCNAB2 in signature has been reported to be involved in cancer. DOCK2, GSTM1, H2AFY and KCNAB2 significant high expression in high risk group compare to low risk group and related to poor prognosis.DOCK2 as a guanine nucleotide exchange factor (GEF) belongs to the dedicators of cytokinesis (DOCK) family, which originally identified in hematopoietic cell and now it's also studied in B cell lymphoma and prostate cancer[27]. DOCK2 has the functions of activating small G proteins such as Rac1/2 and subsequently activates downstream pathways which involved in survival, proliferation, and migration of cancer[28].it has also been demonstrated that DOCK2 was abnormally elevated expressed in B-cell lymphoma and the overexpressed DOCK2 correlated with the reduced prognosis of chronic lymphocytic leukemia[29, 30]. GSTM1 (glutathione S-transferase M1) is a member of the family of cytosolic GSTs and the null genotype of GSTM1 been proven to be associated with risk of colorectal cancer, renal cell carcinoma, esophageal cancer, nasopharyngeal cancer and bladder cancer[31–35].LAPTM5 (lysosomal-associated protein transmembrane 5) is a membrane protein that can inhibit the expression of T cell receptor (TCR) and play a positive role in migration and invasion of ovarian cancer cell but play a negative regulator of T cell or B cell receptor downstream signaling[36–38].SYK(spleen tyrosine kinase) is an important component involved in immune receptor signal transduction and is found to be highly expressed in most PTCLs[39]. Moreover, the inhibitor of SYK was shown to not only inhibit T-cell lymphoma cell lines proliferation but also induce apoptosis[40]. In our study, the prognosis of the SYK high-risk group is better than that of the low-risk group, which may be attributed to the absent expression of SYK in some lymphoma with worse prognosis[41].But it cannot be ruled out that it has a protective effect in some subtype of PTCLs, because it has been reported that SYK has a protective effect in some solid tumor[42–44].
Limitations of the present study should be acknowledged. Firstly, the sample size might not be adequate and may lead to selection bias. Secondly, lack of complete clinical characteristics and absent comprehensive analysis of signature and clinical features. Thirdly, no stratified analysis in all subtype of PTCLs was performed due to the PTCLs case classification data were not available. what's more, additional genetic and experimental studies are required to elucidate the mechanism and the function of these genes that be included in signature which in the carcinogenesis and progression of PTCLs. Finally, our results in more larger samples or more external independent datasets need further validation