JUNB mediates oxaliplatin resistance via the MAPK signaling pathway in gastric cancer by chromatin accessibility and transcriptomic analysis.

Currently, platinum-containing regimens are the most commonly used regimens for advanced gastric cancer patients, and chemotherapy resistance is one of the main reasons for treatment failure. Thus, it is important to reveal the mechanism of oxaliplatin resistance and to seek effective intervention strategies to improve chemotherapy sensitivity, thereby improving the survival and prognosis of gastric cancer patients. To understand the molecular mechanisms of oxaliplatin resistance, we generate an oxaliplatin-resistant gastric cancer cell line and conduct assay for transposase-accessible chromatin sequencing (ATAC-seq) and RNA sequencing (RNA-seq) for both parental and oxaliplatin-resistant AGS cells. A total of 3232 genomic regions are identified to have higher accessibility in oxaliplatin-resistant cells, and DNA-binding motif analysis identifies JUNB as the core transcription factor in the regulatory network. JUNB is overexpressed in oxaliplatin-resistant gastric cancer cells, and its upregulation is associated with poor prognosis in gastric cancer patients, which is validated by our tissue microarray data. Moreover, chromatin immunoprecipitation sequencing (ChIP-seq) analysis reveals that JUNB binds to the transcriptional start site of key genes involved in the MAPK signaling pathway. Knockdown of JUNB inhibits the MAPK signaling pathway and restores sensitivity to oxaliplatin. Combined treatment with the ERK inhibitor piperlongumine or MEK inhibitor trametinib effectively overcomes oxaliplatin resistance. This study provides evidence that JUNB mediates oxaliplatin resistance in gastric cancer by activating the MAPK pathway. The combination of MAPK inhibitors with oxaliplatin overcomes resistance to oxaliplatin, providing a promising treatment opportunity for oxaliplatin-resistant gastric cancer patients.

CXCL13 expression is prognostic and predictive for postoperative adjuvant chemotherapy benefit in patients with gastric cancer.

BACKGROUND: Chemokine (C-X-C motif) ligand 13 (CXCL13/BLC/BCA-1) is a cytokine from C-X-C chemokine family, which is selectively chemotactic for B cells. Previous research has demonstrated that high CXCL13 expression is correlated to poor prognosis in various cancers. However, the association between CXCL13 expression and gastric cancer is still unclear. METHODS: Intratumoral CXCL13 expression was evaluated by immunohistochemistry using a semi-quantitative method (modified H-score) in a testing set of 214 and a validation set of 227 randomly selected gastric cancer patients resected in 2008 in one institution. The median value was used as the cut-off point. We performed correlative analysis of CXCL-13 expression with clinicopathological variables, Kaplan-Meier analysis for association with overall survival (OS), and multivariate modeling. RESULTS: High CXCL13 expression was associated with larger tumor diameter and shorter OS. By multivariate analysis, CXCL13 expression was associated with OS independently from clinicopathological factors. Within the T2-4 stage patients group, low CXCL13 expression was associated with longer survival, especially in the subgroup of patients (57.6%) who received adjuvant chemotherapy. CONCLUSIONS: Intratumoral CXCL13 expression appears as an independent prognostic marker for patients after gastric cancer resection. In addition, CXCL13 expression may serve as a predictive biomarker of response to postoperative adjuvant chemotherapy in these patients.

Nestin overexpression reduces the sensitivity of gastric cancer cells to trastuzumab.

Background: Trastuzumab (TRA) shows significant efficacy in patients with human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC). While TRA can help treat HER2-positive breast cancer, TRA resistance is a key clinical challenge. Nestin reportedly regulates the cellular redox homeostasis in lung cancer. This study aimed at identifying the functions of Nestin on the TRA sensitivity of HER2-positive GC cells. Methods: Real-time polymerase chain reaction (PCR) and Western blotting (WB) were performed to explore the association between the mRNA and protein expression profiles, respectively, of Nestin and the Keap1-Nrf2 pathway. The influence of Nestin overexpression on the in vitro sensitivity of GC cells to TRA was explored by Cell Counting Kit-8 (CCK-8) assay, colony formation assay, reactive oxygen species (ROS) detection, and flow cytometry. Results: TRA treatment caused Nestin downregulation in two HER2-positive GC cell lines (MKN45 and NCI-N87). Nestin overexpression reduced the sensitivity of GC cells to TRA. The expression and activity of Nrf2 and relevant downstream antioxidant genes were increased by Nestin overexpression. Nestin overexpression also significantly suppressed TRA-induced apoptosis and ROS generation. In vivo tumor growth experiment with female BALB/c nude mice indicated that Nestin upregulation restored the tumor growth rate which was inhibited by TRA treatment. Conclusions: Collectively, the inhibitory effect of Nestin on the TRA sensitivity of cells to TRA was confirmed in this study. These results imply that the antioxidant Nestin-Nrf2 axis may play a role in the mechanism underlying the resistance of GC cells to TRA.

ANGPTL6-mediated angiogenesis promotes alpha fetoprotein-producing gastric cancer progression.

Alpha-fetoprotein (AFP)-producing gastric cancer (AFPGC) is regarded as a rare but highly malignant gastric adenocarcinoma subtype and its clinic pathological presentation mimics hepatocellular carcinoma. However, the underlying mechanism of this disease remains elusive. The level of ANGPTL6 in AFPGC cell lines is much higher than that of common types of gastric cancer cells. A high level of ANGPTL6 confers a poor prognosis and is correlated with the expression of CD34 (an endothelial cell marker). ANGPTL6 promotes endothelial cell migration and tube formation, Moreover, ANGPTL6 knockdown inhibits cancer cell apoptosis and invasiveness. Mechanistically, ANGPTL6 activates the ERK1/2 and AKT pathways. Treatment of ERK1/2 or AKT inhibitor can attenuated cell migration and tube formation. ANGPTL6 loss results in tumor growth in vivo. Our study revealed that ANGPTL6 is an important driver gene of angiogenesis in AFPGC development. These findings provide not only an effective biomarker for diagnosis but also an attractive therapeutic target for use in AFPGC patients.

Hepatoid Adenocarcinoma of Stomach: Emphasis on the Clinical Relationship with Alpha-Fetoprotein-Positive Gastric Cancer.

AIMS: Both hepatoid adenocarcinoma of stomach (HAS) and alpha-fetoprotein-positive gastric cancer (AFPGC) are rare but aggressive subtypes of gastric cancer, but few studies focus on the clinicopathologic differences and prognostic factors between them because of their rarity and histologic overlap. And the significance of AFP level in HAS prognosis was not well studied. METHODS: 41 patients with AFPGC and 52 patients with HAS were included in this study. The clinicopathologic features were compared by Chi-square analysis. Prognostic factors for overall survival (OS) and disease-free survival (DFS) were analyzed with the Kaplan-Meier method. RESULTS: The patients with HAS were of a younger age compared with AFPGC, and nearly 60% of tumor located in the gastric antrum and the gastric fundus of cardia. The OS of AFPGC was shorter than that of HAS, due to a higher rate of metastasis. Furthermore, the survival analysis showed that HAS with high AFP expression (AFPHigh HAS) had a significantly poorer OS compared to HAS with low AFP expression (AFPLow HAS) (P=0.046). CONCLUSIONS: Compared with AFPGC, the patients of HAS were of a younger age and had less rate of liver and other organ metastasis. The serum AFP level was a sensitive prognostic indicator for OS. Therefore, much attention should be paid to AFPHigh HAS in clinical practice.

HnRNPR-CCNB1/CENPF axis contributes to gastric cancer proliferation and metastasis.

Gastric cancer (GC) is a common disease globally with high mortality rate. It is therefore necessary to develop novel therapies targeting specific events in the pathogenesis of GC. Some hnRNP family members are involved in multiple cancer biological behaviors. However, the potential function and mechanism of hnRNPR, a new molecule of hnRNP family in GC remains unknown. We found that the expression of hnRNPR was significantly overexpressed in multiple cancers compared to the normal tissues. Functionally, hnRNPR promoted cancer cell proliferation, migration, and invasion. Knockdown of hnRNPR in two type mice models, with two types of tumors models decreased the tumor aggressiveness and metastasis. Mechanistically, hnRNPR targeted oncogenic pathways by stabilizing the expression of CCNB1 and CENPF mRNA level. Knockdown of CCNB1 and CENPF abolished the hnRNPR-induced cell growth and invasion, respectively. Furthermore, the protein level of hnRNPR in the tumor was positively correlated with the expression of CCNB1 and CENPF in clinical samples. Together, these results indicate that overexpression of hnRNPR promoted the aggressiveness of GC by increasing the mRNA expression of CCNB1 and CENPF. HnRNPR-CCNB1/CENPF axis may be a potential therapeutic target for GC treatment.