| BackgroundNasopharyngeal carcinoma, short for NPC, is common in south coastal cities of China, with characteristics of race sensitivity, family heredity and obvious region gathering. The polygenetic disease of NPC has complicated etiologies, influenced by many kinds of factors, including EB virus infection, genetic factors, dietary habits and environmental factors. But the exact pathogenesis of nasopharyngeal carcinoma has not been clear so far. Virus infection especially EB virus is one of the currently recognized incidence factors of nasopharyngeal carcinoma. EB virus can mostly be detected in south Chinese patients with nasopharyngeal carcinoma patient. Nasopharyngeal carcinoma origins from nasopharyngeal mucosal epithelium and lacunae columnar epithelium. According to the degree of differentiation of nasopharyngeal carcinoma, NPC is divided into low differentiated squamous cell carcinoma, high and undifferentiated carcinoma, adenocarcinoma and vesicular nucleus cell carcinoma. Nasopharyngeal carcinoma is sensitivity to radiotherapy. And radiotherapy is the first choice in the treatment of nasopharyngeal carcinoma. But operation and chemotherapy are also indispensable for high differentiated cancer and recurrence after radiotherapy. It is difficult to treat NPC because of its complex, deep and hidden onset location. Individual specific treatment and drug therapy are insufficient, which leads to poor treatment effect. At present, pathogenesis of nasopharyngeal carcinoma has not been fully elucidated. So to find a molecular marker is beneficial to early diagnosis, individualized treatment and prognosis assessment of nasopharyngeal carcinoma.Nemo-like kinase, short for NLK, is a conserved serine/threonine protein kinase, which plays an important role in cell apoptosis, inflammatory signal transduction, cell proliferation and metabolism process. It can inhibit tumor occurrence in prostate cancer, ovarian cancer, breast cancer, glioma, colorectal cancer, and promote tumor progression in human hepatocellular carcinoma, gallbladder cancer, oral squamous adenocarcinoma. Because NLK can be involved in embryonic development, bone formation and growth, the biological rhythm, it is closely related to the occurrence and development of tumorbiology. Especially, NLK has the two-sided nature on tumors, so it is getting more attention. In non small cell lung cancer, expression of NLK was reduced, compared to normal lung tissue, with significant differences. Reduction of NLK leads to increase of complex β-catenin/TcF and the downstream of Wnt protein, c-Myc, DDK1 CycDl and Axin2 increase. Decrease expression of NLK regulatesnon small cell lung cancer through inhibition of Wnt pathway. Expression of NLK in prostate cancer metastasis was lower. Overexpression of NLK can apoptosis of prostate cancer cells, by reducing androgen receptor transcriptional activity. But the specific mechanism of NLK and androgen receptor pathway has not been fully elucidated. The similar reduction of NLK can be detected in ovarian cancer tissue samples, with time correlation and tumor staging and grading. The decrease in NLK expression predicted poor prognosis of ovarian cancer. Wnt pathway may be involved in ovarian cancer. The sensitivity of ovarian cancer to cisplatin was also affected by NLK, regulated through p38 pathway. Decreased NLK expression can be seen in glioma patients, which leads to survival rate was lower than patients with high NLK expression. Overexpression of NLK in glioma cell lines can increase caspase-3 activity, inhibit glioma cells proliferating. So NLK may be activated by caspase-3 apoptosis pathway in glioma cells. Study on expression of NLK in breast cancer, confirmed its overexpression can inhibit the proliferation of breast cancer cells and induces apoptosis. In breast cancer tissue, the expression of NLK was related with clinical classification and Ki-67, c-Myb. Ki-67 promotes cell proliferation and cell cycle. Overexpression of NLK in breast cancer, c-Myb decreased in GO and G1 phase, so NLK may be associated with the phosphorylation of c-Myb degradation. c-Myc and Bcl-2 expression decreased, which blocked the cell cycle. NLK induced apoptosis through arresting cell cycle, inhibiting the occurrence of breast cancer. The expression of NLK in hepatocellular carcinoma is 2 times of the normal tissue, indicating that NLK promoted hepatocellular carcinoma cance. Silencing the expression of NLK in hepatocellular carcinoma cells can obviously inhibit the growth of tumor cells. The cells in G1-S phase increased, but the apoptosis of hepatoma cells did not significantly increase. Knockdown NLK expression could inhibit beta-catenin. NLK can promote gallbladder carcinoma. Inhibiting the expression of NLK in gallbladder cancer cell lines can significantly reduce tumor cell proliferation and tumor formation ability, migration ability, but its mechanism is still not clear. Knockdown of NLK can inhibit cell proliferation and tumor formation in oral cancer cell lines by blocking the cell cycle from G0/G1 phase to S phase, which suggests that NLK may promote the development of oral cancer through the intervention of the cell cycle. But the expression and function of NLK in nasopharyngeal carcinoma has not been studied. Whether NLK can be as a diagnostic marker of nasopharyngeal carcinoma is needed for further discussion.Methods:1 352 cases and samples of patients with primary nasopharyngeal were collected, and 176 cases of normal tissues nearby carcinoma were also collected. Clinical data of all patients were recorded on patients, including age, gender, pathological type, the distribution of primary symptoms, lymph node metastasis, clinical staging. All patients without operation before samples were collected. The causes of death in patients were confirmed according to clinical records.2 Hematoxylin eosin (HE) staining was used to determine the grading of tumor.3 SABC immunohistochemical method was employd to detect the NLK expression in nasopharyngeal carcinoma.4 Cox univariate and multivariate regression analysis was used to analyze the correlation of DFS and OS between NLK and nasopharyngeal carcinoma.5 Kaplan-Meier survivacurve analysis was used to analyze the correlation of DFS and OS between NLK and nasopharyngeal carcinoma.6 Human nasopharyngeal carcinoma cell line CNE2 cells was cultured in vitro.7siRNA technique was used to knockdown expression of NLK in nasopharyngeal carcinoma cells.8 Real time PCR was used to detect the expression of NLK mRNA in nasopharyngeal carcinoma cell.9 Western Blot was used to detect the expression of NLK protein in nasopharyngeal carcinoma cell.10 MTT assay was used to detect the effect of NLK on the proliferation of nasopharyngeal carcinoma cell.11 Clone formation assay was used to detect the effect of NLK on the clone formation of nasopharyngeal carcinoma cell.12 Migration experiment was used to detect the effect of NLK on migration of nasopharyngeal carcinoma cell.13 Transwell chamber invasion assay was used to detect the effect of NLK on invasiveness of nasopharyngeal carcinoma cells.14 Caspase 3 activity assay was used to detect the effect of NLK on apoptosis of nasopharyngeal carcinoma cells.Result1 Patients included 204 men and 148 women, and age at the time of diagnosis varied between 12 and 69 years (45.2±17.9 years). According to TNM stage, a total of 144 cases was T4 stage, accounting for 40.9%, followed by the patients in T2 and T3 stage. Majority of the patients were in N2-N3 stage,227 cases, accounted for 64.5%. The rest of the patients were with stage NO-N1 disease.The majority of the patient were in MO stage,223 cases, accounting for 63.4%, the remaining patients in M1 stage.101 cases were in theⅠ-Ⅱ, the majority of patients were in stage Ⅲ-Ⅳ,251 cases, accounting for 71.3%.2 Among all the 352 NPC biopsies,54%(190/352) of NPC samples were classified as positive for NLK expression and 46%(162/352) as negative for NLK. Immunohistochemical staining of NLK was predominantly located in the nucleus. In contrast, NLK was negative in adjacent tissues from all the 176 specimens.3 Remarkable associations were not observed between NLK status and tumor histology, or patients’gender (P=0.79)4 Regional lymph node status was found to be significantly associated with NLK status (P=0.003). Positive NLK expression was also correlated with the distant metastases (P<0.001).5 With regard to DFS, among 286 NPC patients for whom follow-up information was available,134 patients (46.9%) relapsed during the follow-up. In Cox univariate regression analysis, a 3-fold higher risk of recurrence was predicted for NPC patients bearing tumors with NLK positivity [hazard ratio (HR)=2.94,95% confidence interval (95%(CI)=1.30-6.52, P=0.011]. Therefore, in addition to tumor extent and TNM stage that were confirmed as significant predictors of DFS (P=0.034 and P=0.014, respectively), NLK overexpression was shown to predict shorter DFS in NPC.6 In accordance, Kaplan-Meier DFS curves demonstrated that NPC patients with NLK-positive tumors had significantly shorter DFS (P=0.0012), in comparison with those NLK-negative ones.7 In the multivariate survival analysis, NLK positivity remained a statistically significant predictor of shorter DFS in NPC, independent of patients’other features, as patients with NLK protein-positive tumors were more prone to relapse (HR=3.46,95% CI=0.96-5.87,P=0.013).8Among the 286 NPC patients for whom follow-up data were available,117 patients (40.9%) died during the follow-up. As demonstrated by Cox univariate regression analysis, NPC patients with positive NLK were at higher risk of death (HR=2.77,95%CI=1.12-5.98, P=0.011), compared to NPC patients whose biopsies were NLK-negative. Consequently, enhanced NLK positivity was an unfavorable prognostic factor of OS. Tumor extent and TNM stage were also significant prognostic factors of OS (P=0.034 and P=0.014, respectively).9 Kaplan-Meier OS curves demonstrated that NPC patients with NLK-positive expression were has worse prognosis than patients with NLK-negative nasopharyngeal tumors (P<0.001).10 In the multivariate Cox regression analysis, NLK positivity predicted a significantly unfavorable prognostic outcome (HR=2.77,95%CI=1.12-5.98, P=0.011). More importantly, NLK positivity retained its independent prognostic significance in NPC (HR=3.15,95%CI=1.33-7.84, P=0.019) even when the multivariate Cox regression model was adjusted for patients’ gender, age, tumor histology, and TNM stage.11 Kaplan-Meier survival analysis was conducted to evaluate the influence of NLK positivity on DFS and OS for metastasis-free NPC patients. As demonstrated in Figure 3, MO patients with NLK-positive tumors had much shorter DFS and OS than did MO patients with NLK-negative malignancies (P<0.001 and P=0.009, respectively).12 SiRNA interference of NLK, the expression of NLK was inhibited, NLK mRNA expression decreased, compared with the control group, with significant difference (P< 0.05).13 SiRNA interference of NLK, the expression of NLK was inhibited, NLK protein expression decreased, compared with the control group, with significant difference (P< 0.05).14 SiRNA interference of NLK, the expression of NLK was inhibited, which leads to inhibit proliferation of NPC cells (P< 0.05).15 SiRNA interference of NLK, the expression of NLK was inhibited, which leads to inhibit colony formation of NPC cells (P< 0.05).16 SiRNA interference of NLK, the expression of NLK was inhibited, which leads to inhibit immigration of NPC cells (P< 0.05).17 SiRNA interference of NLK, the expression of NLK was inhibited, which leads to inhibit invasion of NPC cells (P< 0.05).18 Knockdown the expression of NLK didn’t affect the activity of caspase 3.Conclusion1 NLK is a good prognostic marker for NPC.2 Patients with NLK-positive NPC had significantly shorter disease-free survival (DFS) and overall survival (OS).3 NLK increases cell proliferation and colony of NPC.4 NLK increases cell invasion and migraion of NPC.5 NLK cann’t affect cell apoptosis of NPC. |
PDF Full Text Request