Na Huang

Metastasis-associated in colon cancer-1 upregulation predicts a poor prognosis of gastric cancer, and promotes tumor cell proliferation and invasion.

Metastasis‐associated in colon cancer‐1 (MACC1) is a newly identified oncogene, and little is known about its role in gastric cancer (GC). Our study was performed to investigate whether MACC1 influences the prognosis of GC patients and to explore the potential mechanisms involved. MACC1 expression was verified to be higher in GC tissues than in adjacent nontumorous tissues by Western blotting. A retrospective analysis of 361 GC patients (Stages I–IV) revealed that higher MACC1 expression was associated with more advanced disease, more frequent postoperative recurrence, more metastases and a higher mortality rate. The disease‐free survival of Stage I–III patients and overall survival of Stage‐IV patients were significantly worse when their tumors showed high MACC1 expression. To investigate the underlying mechanisms, MACC1 overexpression and downregulation were established in two GC cell lines (BGC‐823 and MKN‐28 cells). MACC1 overexpression significantly accelerated tumor growth and facilitated metastasis in athymic mice. MACC1 also promoted the proliferation, migration and invasion of both GC cell lines. Moreover, gastric MACC1 mRNA expression levels were significantly correlated with markers of the epithelial‐to‐mesenchymal transition (EMT) in patients with GC. MACC1 overexpression upregulated mesenchymal–epithelial transition factor and induced changes to markers of EMT, whereas silencing of MACC1 reversed all these changes. These findings provide some novel insights into the role of MACC1, a gene that contributes to a poor prognosis of GC by promoting tumor cell proliferation and invasion as well as the EMT.

Long non-coding RNA MALAT1 promotes gastric cancer tumorigenicity and metastasis by regulating vasculogenic mimicry and angiogenesis.

MALAT1 is an oncogenic long non-coding RNA that has been found to promote the proliferation of many malignant cell types and non-malignant human umbilical vein endothelial cells (HUVECs). However, the functions of MALAT1 in vasculogenic mimicry (VM) and angiogenesis and the potential mechanisms responsible have not yet been investigated in any malignancy. Here, in situ hybridization and CD31/periodic acid-Schiff double staining of 150 gastric cancer (GC) clinical specimens revealed that MALAT1 expression was tightly associated with densities of VM and endothelial vessels. MALAT1 knockdown markedly reduced GC cell migration, invasion, tumorigenicity, metastasis, and VM, while restricting HUVEC angiogenesis and increasing vascular permeability. Moreover, MALAT1 was found to regulate expression of VE-cadherin, β-catenin, MMPs 2 and 9, MT1-MMP, p-ERK, p-FAK, and p-paxillin, which have been established as classical markers of VM and angiogenesis and components of associated signaling pathways. Consistent with this, the p-ERK inhibitors U0126 and PD98059 both effectively blocked GC cell VM. In conclusion, MALAT1 can promote tumorigenicity and metastasis in GC by facilitating VM and angiogenesis via the VE-cadherin/β-catenin complex and ERK/MMP and FAK/paxillin signaling pathways.

Elevated Orai1 and STIM1 expressions upregulate MACC1 expression to promote tumor cell proliferation, metabolism, migration, and invasion in human gastric cancer.

ORAI calcium release-activated calcium modulator 1 (Orai1)- and stromal interacting molecule 1 (STIM1)-mediated store-operated Ca(2+) entry (SOCE) have been increasingly implicated in tumor progression; however, its role in gastric cancer (GC) is not well elucidated. We aimed to determine whether SOCE influences GC prognosis and elucidate the underlying mechanisms. Orai1 and STIM1 expressions were higher in GC tissues compared to adjacent non-tumor tissues according to RT-PCR and western blotting. Higher Orai1 and/or STIM1 expression was associated with more advanced disease, more frequent recurrence, and higher mortality rates in our study of 327 GC patients. The disease-free survival rates of Stage I-III patients and the overall survival rates of Stage IV patients were significantly worse when the tumors had high Orai1 and/or STIM1 expressions. Orai1 and/or STIM1 knockdown caused significantly reduced tumor growth and metastasis in athymic mice. Orai1 and/or STIM1 knockdown lowered the proliferation, metabolism, migration, and invasion of two GC cell lines. Also, Orai1 and/or STIM1 knockdown changed the markers of the cell cycle and epithelial-mesenchymal transition (EMT). These effects were reversed by metastasis-associated in colon cancer-1 (MACC1) overexpression. In summary, the composite molecules of SOCE suggest a poor prognosis for GC by promoting tumor cell proliferation, metabolism, migration, and invasion by targeting MACC1.

Voltage‐gated sodium channel Nav1.7 promotes gastric cancer progression through MACC1‐mediated upregulation of NHE1

Voltage‐gated sodium channels (VGSCs), which are aberrantly expressed in several human cancers, affect cancer cell behavior; however, their role in gastric cancer (GC) and the link between these channels and tumorigenic signaling remain unclear. The aims of this study were to determine the clinicopathological significance and role of the VGSC Nav1.7 in GC progression and to investigate the associated mechanisms. Here, we report that the SCN9A gene encoding Nav1.7 was the most abundantly expressed VGSC subtype in GC tissue samples and two GC cell lines (BGC‐823 and MKN‐28 cells). SCN9A expression levels were also frequently found to be elevated in GC samples compared to nonmalignant tissues by real‐time PCR. In the 319 GC specimens evaluated by immunohistochemistry, Nav1.7 expression was correlated with prognosis, and transporter Na+/H+ exchanger‐1 (NHE1) and oncoprotein metastasis‐associated in colon cancer‐1 (MACC1) expression. Nav1.7 suppression resulted in reduced voltage‐gated sodium currents, decreased NHE1 expression, increased extracellular pH and decreased intracellular pH, and ultimately, reduced invasion and proliferation rates of GC cells and growth of GC xenografts in nude mice. Nav1.7 inhibition led to reduced MACC1 expression, while MACC1 inhibition resulted in reduced NHE1 expression in vitro and in vivo. Mechanistically, the suppression of Nav1.7 decreased NF‐κB p65 nuclear translocation via p38 activation, thus reducing MACC1 expression. Downregulation of MACC1 decreased c‐Jun phosphorylation and subsequently reduced NHE1 expression, whereas the addition of hepatocyte growth factor (HGF), a c‐Met physiological ligand, reversed the effect. These results indicate that Nav1.7 promotes GC progression through MACC1‐mediated upregulation of NHE1. Therefore, Nav1.7 is a potential prognostic marker and/or therapeutic target for GC.

MACC-1 Promotes Endothelium-Dependent Angiogenesis in Gastric Cancer by Activating TWIST1/VEGF-A Signal Pathway.

Endothelium-dependent angiogenesis is thought to be a crucial step in cancer progression. We previously reported that metastasis-associated in colon cancer-1 (MACC1) contributed to the vasculogenic mimicry in gastric cancer (GC), but it remains unknown whether MACC1 promotes endothelium-dependent angiogenesis of GC and whether TWIST1 is involved in this process. In the present study, we detected MACC1 expression and microvessel density (MVD) by immunohistochemistry in 159 patients with stage I-III GC, and investigated the role of TWIST1 and vascular endothelial growth factor A (VEGF-A) in MACC1-induced endothelium-dependent angiogenesis using nude mice with GC xenografts, and human umbilical vein endothelial cells (HUVECs) that were co-cultured with conditioned media from overexpression and interference MACC1 GC cells. We found that MACC1 expression was positively correlated with an increased MVD and tumor recurrence in GC patients. In GC xenograft models, MACC1 elevated MVD and upregulated the expression of VEGF-A as well as accelerated tumor growth. In addition, MACC1 obviously increased the expression of TWIST1 and induced tube-like formation of HUVECs, whereas attenuation of TWIST1 suppressed the protein expression of VEGF-A and repealed the effect of MACC1 on tube formation. Our findings shed light on the function of MACC1 in endothelium-dependent angiogenesis of GC and suggest potential prognostic and therapeutic value.

Clinical significance of accurate identification of lymph node status in distant metastatic gastric cancer

PURPOSE The clinical consequences of accurately identifying lymph node (LN) status in distant metastatic gastric cancer (DMGC) are unclear. We aimed to determine the prognostic significance of N stage, positive LN (PLN) count, and the positive LN ratio (LNR). We also retrospectively compared survival outcomes of DMGC patients stratified by LN dissection (LND). RESULTS LND was performed in 1593 patients. The CSS was significantly different between groups divided according to N stage, PLN, and LNR in DMGC patients who underwent LND. Lower LNR was an independent predictor of longer survival in all kinds of patients cohorts, whereas PLN was not such a predictor. PLN count correlated with LND number and LNR. No correlation existed between LNR and LND number. Undergoing LND and having a higher number of dissected LNs were associated with superior CSS. MATERIALS AND METHODS Data from 1889 DMGC patients treated between 2004 and 2009, and documented in the Surveillance, Epidemiology, and End Results (SEER) registry, were reviewed. Pearsons correlation coefficient and the Chi-square test were used to study the relationships between LND number, PLN count, N stage, and the LNR. Cancer-specific survival (CSS) was evaluated using Kaplan-Meier analysis, with the log-rank test performed for univariate analysis (UVA) and the Cox proportional hazards model employed for multivariate analysis (MVA). CONCLUSION LN metastatic variables play important roles in the prognostic evaluation and treatment decisions of DMGC patients. Accurate identification of LN status in DMGC patients is critical. LND performance is associated with increased survival and has clinical practicability.

MACC1 decreases the chemosensitivity of gastric cancer cells to oxaliplatin by regulating FASN expression

The effect of chemotherapeutic agents is limited as a result of drug resistance, which demands prompt solutions provided by clinical studies. To date, the underlying mechanisms of chemotherapy resistance are relatively unknown. Metastasis-associated in colon cancer 1 (MACC1) is an oncogene associated with the progression and prognosis of gastric cancer (GC). Bioinformatic analysis revealed that MACC1 is positively associated with fatty acid synthase (FASN), a major enzyme of lipogenesis, and drives chemoresistance to oxaliplatin in GC. Similar findings were demonstrated in two GC cell lines (BGC-823 and MKN-28) with MACC1 ectopic expression. We next employed FASN inhibitor C75 or siFASN (small interfering RNA targeted to FASN) to block endogenous fatty acid metabolism and it was revealed that cell proliferation and chemoresistance to oxaliplatin induced by MACC1 upregulation were attenuated by FASN blockade to various extents. Conclusively, these outcomes highlight a novel role of MACC1 in GC cell lipogenesis, and suggest that MACC1 may be an attractive target to decrease oxaliplatin resistance in GC.

Mitochondrial topoisomerase I absence enhances aerobic glycolysis in cancer

Aerobic glycolysis plays an important role in cancer progression. New target genes regulating cancer aerobic glycolysis must be explored to improve patient prognosis. Mitochondrial topoisomerase I (TOP1MT) deficiency suppresses glucose oxidative metabolism but enhances glycolysis in normal cells. Here, we examined the role of TOP1MT in gastric cancer (GC) and attempted to determine the underlying mechanism. Using in vitro and in vivo experiments and analyzing the clinicopathological characteristics of patients with GC, we found that TOP1MT expression was lower in GC samples than in adjacent nonmalignant tissues. TOP1MT knockdown significantly promoted GC migration and invasion in vitro and in vivo. Importantly, TOP1MT silencing increased glucose consumption, lactate production, glucose transporter 1 expression and the epithelial-mesenchymal transition (EMT) in GC. Additionally, regulation of glucose metabolism induced by TOP1MT was significantly associated with lactate dehydrogenase A (LDHA) expression. A retrospective analysis of clinical data from 295 patients with GC demonstrated that low TOP1MT expression was associated with lymph node metastasis, recurrence and high mortality rates. TOP1MT deficiency enhanced glucose aerobic glycolysis by stimulating LDHA to promote GC progression.

Impact of liver tumor percutaneous radiofrequency ablation on circulating tumor cells

Radiofrequency ablation has become an increasingly common therapeutic technique for patients with hepatocellular carcinoma or metastatic liver tumors. However, reports on the effect of percutaneous radiofrequency ablation (PRFA) on circulating tumor cells (CTCs) are limited. The present study aimed to further investigate the impacts of PRFA on the numbers and phenotypes of CTCs in patients with hepatocellular carcinoma or metastatic liver tumors. A total of 43 patients with hepatocellular carcinoma or 7 types of metastatic liver tumors were treated with PRFA. A total of 5 ml blood per sample were collected from the peripheral circulation 30 min before and 3 days after PRFA. The total number of CTCs significantly increased 3 days after PRFA, and the mesenchymal phenotype CTCs, which also increased significantly, significantly contributed to the overall increase in CTCs. Furthermore, the lymphocyte levels were significantly decreased following PRFA, and the CTC level was significantly higher in patients with decreased lymphocyte levels compared with those with increased lymphocyte levels. Liver tumor PRFA may increase the level of mesenchymal phenotype CTCs, which is significantly associated with the lymphocyte count. Factors pertaining to the performance of PRFA were also investigated in the present research, but no significant results were identified.

Inhibition of SLC1A5 sensitizes colorectal cancer to cetuximab: SLC1A5 inhibition enhances the efficacy of cetuximab

Cetuximab resistance is a key barrier in treating metastatic colorectal cancer (mCRC). Targeting of metabolic resources import could resensitize drug‐resistant cancer cells to anticancer treatments. Here we showed that the expression of the glutamine transporter solute carrier 1 family member 5 (SLC1A5) in clinical CRC samples of patients resisted to cetuximab was significantly higher than in those of patients responded to cetuximab. Inhibition of SLC1A5 by shRNA‐mediated gene silencing or pharmacological inhibitor significantly suppressed the growth of CRC. Moreover, inhibition of SLC1A5 significantly enhanced the inhibitory efficacy of cetuximab on CRC proliferation both in vitro and in vivo. Mechanistically, SLC1A5 inhibition facilitated EGFR degradation through the ubiquitin‐proteasome pathway, and decreased the expression of nuclear EGFR, both of which might have contribution to the improved response to cetuximab. This study provides the metabolic molecule SLC1A5 as a potential therapeutic target to increase the efficacy of cetuximab on CRC.