GRP78Expression In Esophageal Squamous Cell Carcinoma And Its Potential Role In Modulating Metastasis

[Background]Human esophageal squamous cell carcinoma (ESCC) ranks the9th mostcommon tumor and the6th leading cause of death from cancer worldwiderespectively. Although the mortality of ESCC has significantly decreasedbecause of the advances in surgery, radiotherapy and chemotherapy,approximately70%of the ESCC patients distributes a poor prognosis due toearly lymph node (LN) metastasis and invasion of neighboring organs atdiagnosis.The development and progression of ESCC is believed to be acomplex process involving the interaction of numerous genes. To date, somegenetic alterations have been reported to be involved in the development ofESCC, such as the overexpression of cyclinD1and c-Myc, mutations of p53and p16. In addition, some genes were reported to involved in the metastasisof ESCC. Matrix metalloproteinases (MMPs) also plays key roles in themetastasis of ESCC. Besides, the Epithelial-mesenchymal transition (EMT)also involved in invasion and metastasis of ESCC, for example E-cadiherin and twist. However, the underlying mechanims responsible for invasion andmetastasis in ESCC remains poorly understood. There is increasing body ofevidence revealed that the glucose-regulated protein GRP78is involved intumor development and progression. GRP78has seen overexpressed in manyhuman cancers such as hepatocellular carcinoma, colon cancer, lung cancer,gastric cancer and so on. Several researches also have showed that theexpression of GRP78was related to invasion and metastasis in humancancers. These findings demonstrate that GRP78may take part in the tumormetastasis. However, the role of GRP78in invasion and metastasis of ESCCremains unknown.【Objective】1. To explore the expression correlation of GRP78in esophageal squamouscell carcinoma tissues.2. To establish and validate of metastatic sublines from EC109and EC9706cells.3. To investigate the level of GRP78expression in highly and non-metastaticESCC cells.4. To further investigate whether GRP78alters the capacity of ESCC cellsfor invasion and migration.5. To further investigate the role and mechanisms of GRP78in metastasisand invasion of ESCC【Methods】1. GRP78expression levels in ESCC tissues were examined by imunohisto-chemistry and the relationships with various clinicopathological features were analyzed statistically.2. RT-PCR and western blot were done to test the relative expression ofGRP78in ESCC tissues with LN metastasis and ESCC tissues without LNmetastasis.3. Highly and non-metastatic subline cells were construct by repeatedtranswell assays and validated in vivo with wound and healing assays andtranswell assyas and in vitro.4. RT-PCR and western blot were done to test the relative expression ofGRP78in non-metastatic cells and high-metastatic ESCC cells.5. Wound and healing assays and transwell assyas were both done toinvestagate the role and mechanisms of GRP78in invasion and metastasisin ESCC cells. In vitro study was done to investagate the role andmechanisms of GRP78in invasion and metastasis in ESCC cells.6. The metastasis related proteins were examined by western blot inGRP78-depleted cells.【Results】1. The overexpression of GRP78is associated with lymph node metastasis inESCC. And patients with positive GRP78expression had a better5-yearsurvival rate than patients with negative GRP78expression.2. Establishment and characterization of metastatic sublines from EC109andEC9706cells. 3. The expression of GRP78is specifically upregulated in highly metastasticcells of ESCC.4. Depletion of GRP78Expression Inhibits Tumor metastasis and invasion inESCC cells in vivo.5. Depletion of GRP78Expression inhibits ESCC metastasis and invasion invitro.6. Depletion of GRP78altered the expression of metastasis-related proteins.【Conclusion】1. GRP78over-expressed in esophageal squamous cell carcinoma tissuesand lymph nodes metastasis cancer tissues. And patients with positiveGRP78expression had a better5-year survival rate than patients withnegative GRP78expression.2. Down-regulating GRP78expression suppressed esophageal cancer cellinvasion and metastasis in vivo and in vitro.3. Down-regulation of GRP78might suppress the metastasis by effecting theexpression of MMP-2and MMP-9in ESCC cells.