The role of HER3 in gastric cancer

HER3: Updates and current biology function, targeted therapy and pathologic detecting methods

Being a member of the EGFR tyrosine kinase family, HER3 has been shown to be overexpressed in a number of cancers, including breast cancer (BC). The kinase activity of HER3 is extremely low, and it forms heterodimers with partners, HER2 in particular, that promote biological processes like cell migration, survival, and proliferation by activating downstream carcinogenic signaling pathways. The overexpression of HER3 is also directly linked to tumor invasion, metastasis, and a poor prognosis. Despite the relatively low expression of HER3 compared to EGFR and HER2, a lot of targeted drugs are making their way into clinical trials and seem to have a bright further. This review aims to summarize the relationship between HER3 overexpression, mutations, and carcinogenicity and drug resistance, starting from the unique structure and kinase activity of HER3. Simultaneously, numerous approaches to HER3 targeted therapy are enumerated, and the clinical detection methods for HER3 that are commonly employed in pathology are sorted and contrasted to offer physicians a range of options. We think that a better knowledge of the mechanisms underlying HER3 in tumors and the advancement of targeted HER3 therapy will contribute to an improved prognosis for cancer patients and an increase in the efficacy of anticancer therapies.

A review of recombinant HER3 affibodies with an effective diagnostic view of cancer cells

One of the most common causes of cancer-related death in women worldwide is breast cancer(Edited)Restore original. Factors such as increased expression of HER family members can contribute to its development. Elevated HER3 expression, especially when combined with other tyrosine kinase receptors such as HER2, plays a significant role in activating cancer pathways crucial for cell survival and proliferation in breast cancer. Detecting high HER3 levels is essential for effective cancer treatment. Affibody proteins, a class including antibodies, are utilized to detect elevated HER3 receptor expression due to their specific high binding affinity. Affibodies, a new type of non-immune probe, show promise in therapy, diagnostics, and biotechnology due to their exceptional specificity and high target protein affinity. The innovative design of these recombinant affibodies not only enhances the accuracy of HER3 detection but also facilitates the development of targeted therapeutic strategies. By employing advanced engineering techniques, these affibodies can be optimized for improved stability and binding efficacy, making them ideal candidates for clinical applications. Additionally, the versatility of affibody-based systems allows for potential integration with imaging technologies, enabling real-time monitoring of HER3 expression and therapeutic response. This multifaceted approach could ultimately lead to more personalized treatment options for patients with HER3-positive breast cancers, thereby improving overall patient management and outcomes in this challenging disease landscape. This study presents recombinant affibodies tailored to bind to HER3 for cancer cell identification, along with novel methods for producing a range of affibody molecules.

HER3-targeted therapy: the mechanism of drug resistance and the development of anticancer drugs

Human epidermal growth factor receptor 3 (HER3), which is part of the HER family, is aberrantly expressed in various human cancers. Since HER3 only has weak tyrosine kinase activity, when HER3 ligand neuregulin 1 (NRG1) or neuregulin 2 (NRG2) appears, activated HER3 contributes to cancer development and drug resistance by forming heterodimers with other receptors, mainly including epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2). Inhibition of HER3 and its downstream signaling, including PI3K/AKT, MEK/MAPK, JAK/STAT, and Src kinase, is believed to be necessary to conquer drug resistance and improve treatment efficiency. Until now, despite multiple anti-HER3 antibodies undergoing preclinical and clinical studies, none of the HER3-targeted therapies are licensed for utilization in clinical cancer treatment because of their safety and efficacy. Therefore, the development of HER3-targeted drugs possessing safety, tolerability, and sensitivity is crucial for clinical cancer treatment. This review summarizes the progress of the mechanism of HER3 in drug resistance, the HER3-targeted therapies that are conducted in preclinical and clinical trials, and some emerging molecules that could be used as future designed drugs for HER3, aiming to provide insights for future research and development of anticancer drugs targeting HER3.

Evaluation of ITGA3 as a Biomarker of Progression and Recurrence in Papillary Thyroid Carcinoma

Objective

To investigate the expression of ITGA3 and its association with clinical outcomes in papillary thyroid carcinoma (PTC).

Methods

The expression level, association with clinicopathologic characteristics, co-expressed genes, signaling pathways of ITGA3 in thyroid cancer were comprehensively analyzed using bioinformatics analysis through multiple public gene databases. PTC specimens and cell lines were used to verify the results of bioinformatics analysis.

Results

Data mining based on the Oncomine database revealed that ITGA3 expression in classical PTC and tall cell variant PTC was much higher than that in normal thyroid tissue except the follicular variant PTC. Analysis based on The Cancer Genome Atlas (TCGA) database showed that the expression of ITGA3 varies greatly in pathological stages, pathological types, tumor invasion stages, and lymph node metastasis stages of thyroid carcinoma. High expression level of ITGA3 was correlated with tumor regional invasion and lymph node metastasis. Multivariate analysis using logistic regression model showed that high expression of ITGA3 was a risk factor that associated with PTC recurrence and lymph node metastasis. Survival analysis showed that patients with high expression of ITGA3 in PTC had a poorer relapse-free survival (RFS) than patients with low expression of ITGA3 (P < 0.05). Immunohistochemistry experiments showed that the expression of ITGA3 in recurrent thyroid cancer tissues was stronger than that in no-recurrent thyroid cancer tissues (P < 0.05). Knockdown of ITGA3 by sh-RNA in PTC cell lines suppresses cell viability and invasive and migrating capacity.

Conclusion

ITGA3 is overexpressed in PTC, especially in those with higher tumor invasion grades and lymph node metastasis, and was associated with recurrence and poor RFS of PTC. High expression of ITGA3 may have the potential role of predicting PTC recurrence and lymph node metastasis.

UHRF2 promotes Hepatocellular Carcinoma Progression by Upregulating ErbB3/Ras/Raf Signaling Pathway

Emerging evidence revealed that UHRF2 was implicated in a variety of human diseases, especially in cancer. However, the biological function, clinical significance and underly mechanisms of UHRF2 in hepatocellular carcinoma (HCC) is largely unknown. We analyzed the expression of UHRF2 in 371 HCC tissues and 50 para-cancerous tissues of TCGA database. We found that UHRF2 was significantly upregulated in HCC tissues, which was further confirmed in HCC cells and tissues by western blot. More importantly, the level of UHRF2 was correlated with pathological grade and clinical stage, and the patients with high level of UHRF2 had lower overall survival, disease-free survival and higher recurrence rate than those with low UHRF2 level. Univariate and multivariate Cox regression analysis revealed that high level of UHRF2 might be an independent prognostic factor for HCC patients. Functional investigations suggested that ectopic expression of UHRF2 could promote the proliferation, migration and invasion of HCC cell lines, whereas knock down of UHRF2 exhibited an opposite effect. Additionally, gene set enrichment analysis indicated that ERBB signaling pathway was upregulated in patients with high level of UHRF2. Pearson correlation analysis indicated that the expression of UHRF2 was positively correlated with ErbB3 and its downstream targets SOS1, Ras and Raf-1. Furthermore, we found that overexpression of UHRF2 could upregulate the expression of ErbB3, SOS1, Ras and Raf-1. Our findings suggested that UHRF2 might accelerate HCC progression by upregulating ErbB3/Ras/Raf signaling pathway and it might serve as a diagnostic marker and therapeutic target for HCC patients.

MiR-125a-5p inhibits cell proliferation, cell cycle progression, and migration while promoting apoptosis in head and neck cancers by targeting ERBB3

OBJECTIVE

Head and neck cancer is one of the most common cancer types worldwide. MicroRNAs play a vital regulatory role in the occurrence and development of cancer. The objective of this study is to explore the mechanism of miR-125a-5p in the proliferation, migration and apoptosis of head and neck cancer cells and define its target genes.

METHODS

The effects of miR-125a-5p on head and neck cancer cells proliferation, cell cycle distribution, apoptosis and migration were evaluated by colony formation, BrdU assay, flow cytometry and transwell assays. The potential target gene of miR-125a-5p was determined by luciferase activity assay and western blot analysis.

RESULTS

In this study, overexpression of miR-125a-5p significantly inhibited the proliferation of head and neck cancer cells, whereas inhibition of miR-125a-5p enhanced their proliferation. BrdU assay and flow cytometry revealed that miR-125a-5p might inhibit the proliferation of cancer cells by causing cell cycle arrest. Cell apoptosis assay and Transwell assay indicated that miR-125a-5p induced cell apoptosis and inhibited cell migration of cancer cells. Other experiments confirmed that miR-125a-5p could significantly downregulate its expression by binding to ERBB3 to inhibit proliferation and ERBB3 could at least partially mediate the inhibition of miR-125a-5p on the proliferation of head and neck cancer cells.

CONCLUSION

The findings of this study suggested that the miR-125a-5p/ERBB3 axis might play a role in the proliferation, regulation of cell cycle, migration and apoptosis of head and neck cancer cells, potentially offering a new target for treatments of head and neck cancers.

A bivalent, bispecific Dab-Fc antibody molecule for dual targeting of HER2 and HER3

Dual targeting of surface receptors with bispecific antibodies is attracting increasing interest in cancer therapy. Here, we present a novel bivalent and bispecific antagonistic molecule (Dab-Fc) targeting human epidermal growth factors 2 and 3 (HER2 and HER3) derived from the Db-Ig platform, which was developed for the generation of multivalent and multispecific antibody molecules. Dab-Fc comprises the variable domains of the anti-HER2 antibody trastuzumab and the anti-HER3 antibody 3-43 assembled into a diabody-like structure stabilized by CH1 and CL domains and further fused to a human γ1 Fc region. The resulting Dab-Fc 2 × 3 molecule retained unhindered binding to both antigens and was able to bind both antigens sequentially. In cellular experiments, the Dab-Fc 2 × 3 molecule strongly bound to different tumor cell lines expressing HER2 and HER3 and was efficiently internalized. This was associated with potent inhibition of the proliferation and migration of these tumor cell lines. Furthermore, IgG-like pharmacokinetics and anti-tumoral activity were demonstrated in a xenograft tumor model of the gastric cancer cell-line NCI-N87. These results illustrate the suitability of our versatile Db-Ig platform technology for the generation of bivalent bispecific molecules, which has been successfully used here for the dual targeting of HER2 and HER3.

Down-Regulation of USP8 Suppresses HER-3 Positive Gastric Cancer Cells Proliferation

Background

Ubiquitin specific peptidase 8 (USP8) has been reported to induce the degradation of several receptor tyrosine kinases such as epidermal growth factor receptor (EGFR), among which human epidermal growth factor receptor-3 (HER-3) is one of them. However, the role and functional mechanisms of USP8 and HER-3 in gastric cancer (GC) remain unknown.

Objective

To explore the function and mechanism of USP8 and HER-3 in the progression of GC.

Materials and Methods

Eighty-eight patients with histologically confirmed GC were recruited for this study. Tumor samples and GC cell lines were used to detect USP8 and HER-3 levels. MGC803 (HER-3 negative GC cell) was selected as the control group and NCI-N87, MKN-45 and AGS (HER-3 positive GC cells) as the experimental group. USP8i and si-RNA were then used to down-regulate USP8 in each group. Apoptosis and cell-cycle experiments were performed to detect the effects of USP8 on GC cells. Cytotoxicity Assay Kit (MTT) and colony formation assays were used to analyze cell proliferation. Cell migration and invasion ability were examined by wound healing. The expression of related mRNA and protein was detected by Western blot and quantitative real-time PCR (qRT-PCR). In vivo experiments were used to examine the effect of USP8 and HER-3.

Results

Patients with high expression of USP8 or HER-3 tumors alone died earlier than those with low expression and the patients with both USP8 and HER-3 high expression had a shorter overall survival than those with the opposite pattern (both USP8 and HER-3 low expression). Down-regulation of USP8 inhibited cell proliferation and cell metastasis and also reduced the HER-3 expression. We also observed that down-regulation of USP8 inhibited the proliferation of GC cells which highly expressed HER-3. Moreover, down-regulation of USP8 could promote the apoptosis of HER3-positive GC cells and inhibit the proliferation of them by affecting the cell-cycle. In vivo studies demonstrated that down-regulation of USP8 inhibited HER-3 positive tumors growth.

Conclusion

Down-regulation of USP8 inhibits HER-3 positive GC cells proliferation in vivo and in vitro, which indicate that USP8 represents a feasible choice as a therapeutic target for HER-3 positive GC cells.

Silencing of LncRNA Metastasis-Associated Lung Adenocarcinoma Transcript 1 Inhibits the Proliferation and Promotes the Apoptosis of Gastric Cancer Cells Through Regulating microRNA-22-3p-Mediated ErbB3

Purpose

This study aimed to investigate the regulatory effects and mechanisms of long non-coding RNA (LncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) on gastric cancer (GC) cells.

Methods

The expression of MALAT1 was detected in GC tissues and two GC cell lines (SGC-7901 and BGC-823). MALAT1 was overexpressed and silenced in GC cells by the transfection of pcDNA-MALAT1 and siRNA-MALAT1, respectively. The proliferation and apoptosis of transfected cells, as well as the tumor volume and weight in mice injected with transfected cells were determined. After identifying the interaction between microRNA-22-3p (miR-22-3p) and MALAT1/epidermal growth factor receptor 3 (ErbB3), the effects of miR-22-3p/ErbB3 silencing on the proliferation and apoptosis of GC cells were evaluated.

Results

MALAT1 was significantly upregulated in GC tissues and cells and negatively associated with the survival of GC patients. Overexpression of MALAT1 significantly promoted the proliferation and inhibited the apoptosis of SGC-7901 cells, while silencing of MALAT1 exerts contrary effects on BGC-823 cells. Silencing of MALAT1 also significantly inhibited the tumor growth in mice. In addition, MALAT1 negatively regulated its target miR-22-3p. Silencing of miR-22-3p reversed the anti-tumor effects of MALAT1 silencing on GC cells. MiR-22-3p negatively regulated its target ErbB3. Silencing of ErbB3 reversed the tumor-promoting effects of miR-22-3p silencing on GC cells.

Conclusion

Silencing of MALAT1 inhibited the proliferation and promoted the apoptosis of GC cells through upregulating miR-22-3p and downregulating ErbB3.

HER2, NF-κB, and SATB1 Expression Patterns in Gastric Cancer and Their Correlation with Clinical and Pathological Parameters

Gastric cancer (GC) is currently recognized as one of the most common and fatal tumor worldwide. The identification of novel biomarkers in relation to clinical information as well as extending the knowledge on a multiple crosstalk between various oncogenic pathways implicated in GC carcinogenesis seems pivotal to limit the disease-associated mortality. Therefore, we assessed the expression of HER2, NF-κB, and SATB1 in a total of 104 gastric adenocarcinomas and 30 normal gastric samples and correlated the expression patterns with each other and with some clinicopathological variables. Protein expression was examined by immunohistochemistry (IHC) on tissue microarrays (TMAs), and fluorescence in situ hybridization (FISH) was employed to detect HER2 amplification. In the studied group, HER2 and SATB1 were found to be overexpressed in gastric cancer tissue in comparison to normal gastric mucosa. The expression status of the former protein was seen to differ according to some clinicopathological features, but without statistical significance, whereas the expression of the latter was not importantly associated with any of them. In turn, the NF-κB protein level was significantly related to the presence of lymph node metastasis. HER2 expression was not significantly correlated with that of other proteins, but a positive correlation was found between the expression of SATB1 and NF-κB. Further studies with a larger group of patients combined with in vitro mechanistic experiments are required to fully elucidate the role and relationship of HER2, NF-κB, and SATB1 expression in gastric cancer progression. However, to the best of our knowledge, this study is the first look at a simultaneous evaluation of these three markers in the samples of gastric cancer patients.

Prevalence of Her3 in gastric cancer and its association with molecular prognostic markers: a Saudi cohort based study

Her 3 is a member of epidermal growth factor receptors. Mutated, oncogenic Her3 is reported in gastric and colonic cancers with emerging evidence that Her3 can be a potential target for molecular therapies. There is a paucity of studies regarding Her3 and its prognostic implications in gastric cancer in our region. In this study, we evaluated prevalence of Her3 in gastric cancer, in a Saudi cohort of cases, along with its association with prognostic markers p53 and Ki-67. The study was conducted in Department of Pathology of King Fahd Hospital of Imam Abdulrahman Bin Faisal University, Dammam, KSA. Fifty cases of gastric carcinoma were selected from the pathology files that fulfilled the inclusion criteria. Clinico-pathological parameters, Laurens histological classification, and immunohistochemical staining for Her3, p53, and Ki-67 were done. Her 3 positive cases were also evaluated for Her-2neu co-expression. Her3 positivity was seen in 16% (n = 8) out of a total of 50 cases. The median age of presentation was 44 years. Within Her3 positive cases, a female preponderance of 63% (n = 5), presence of high grade tumors in 75% (n = 6), diffuse gastric carcinoma in 63% (n = 5), diffuse to focal p53 positivity in 63% (n = 5), and a high to moderate Ki-67 proliferation index in 75% (n = 6) of cases was seen. Her3 expression was independent of Her-2neu status. Her3 prevalence of 16% with a median age of 44 years at presentation was less than in other reported studies, highlighting the concept of ethnic and regional variation in tumor characteristics. Her3 association with diffuse gastric carcinoma, high grade tumors, diffuse to focal p53 positivity and high to moderate Ki-67 proliferation index points towards a more aggressive clinical behavior.

Optimization of HER3 expression imaging using affibody molecules: Influence of chelator for labeling with indium-111

Radionuclide molecular imaging of human epidermal growth factor receptor 3 (HER3) expression using affibody molecules could be used for patient stratification for HER3-targeted cancer therapeutics. We hypothesized that the properties of HER3-targeting affibody molecules might be improved through modification of the radiometal-chelator complex. Macrocyclic chelators NOTA (1,4,7-triazacyclononane-N,N',N''-triacetic acid), NODAGA (1-(1,3-carboxypropyl)-4,7-carboxymethyl-1,4,7-triazacyclononane), DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), and DOTAGA (1,4,7,10-tetraazacyclododececane,1-(glutaric acid)-4,7,10-triacetic acid) were conjugated to the C-terminus of anti-HER3 affibody molecule Z08698 and conjugates were labeled with indium-111. All conjugates bound specifically and with picomolar affinity to HER3 in vitro. In mice bearing HER3-expressing xenografts, no significant difference in tumor uptake between the conjugates was observed. Presence of the negatively charged 111In-DOTAGA-complex resulted in the lowest hepatic uptake and the highest tumor-to-liver ratio. In conclusion, the choice of chelator influences the biodistribution of indium-111 labeled anti-HER3 affibody molecules. Hepatic uptake of anti-HER3 affibody molecules could be reduced by the increase of negative charge of the radiometal-chelator complex on the C-terminus without significantly influencing the tumor uptake.

TROP2 promotes the proliferation and metastasis of glioblastoma cells by activating the JAK2/STAT3 signaling pathway

Trophoblast cell surface antigen 2 (TROP2), a single transmembrane domain protein, is often found to be highly expressed in various types of human cancers. However, the biological function and molecular mechanism of TROP2 in glioblastoma have not been fully elucidated, particularly in regards to cell proliferation and metastasis of glioblastoma cells. In the present study, it was demonstrated that TROP2 expression was increased in glioblastoma tissues and glioblastoma cell lines by immunohistochemical analysis and western blot analysis. High TROP2 expression was significantly correlated with the poor survival of glioblastoma patients. MTT assay, BrdU incorporation assay, flow cytometry and Transwell assay were performed to demonstrate that knockdown of TROP2 in glioblastoma cells inhibited cell proliferation and metastasis. We found that the effects of TROP2-knockdown on glioblastoma cells were associated with the inhibition of JAK2 and STAT3 phosphorylation and decreased transcription of STAT3 target genes. In addition, blocking the activation of JAK2/STAT3 signaling by WP1066 negated the effects of TROP2 overexpression. Furthermore, exogenous IL-6, which functions as a potent activator of JAK2/STAT3 signaling, was able to rescue the phosphorylation of JAK2 and STAT3 in TROP2-silenced glioblastoma cells and regulate phenotypic changes in these cells. Therefore, we revealed a novel mechanism by which TROP2 activates the JAK2/STAT3 pathway to promote the growth and metastasis of glioblastoma cells. These data offer insight into the function of TROP2 in glioblastoma and indicate that TROP2 is a promising biomarker and therapeutic target for glioblastoma patients.

SNP rs3202538 in 3'UTR region of ErbB3 regulated by miR-204 and miR-211 promote gastric cancer development in Chinese population

Background/aims

ErbB3 is an oncogene which has proliferation and metastasis promotion effects by several signaling pathways. However, the individual expression difference regulated by miRNA was almost still unknown. We focused on the miRNAs associated SNPs in the 3′-UTR of ErbB3 to investigate the further relationship of the SNPs with miRNAs among Chinese gastric cancer (GC) patients.

Methods

We performed case–control study including 851 GC patients and 799 cancer-free controls. Genotyping, real-time PCR assay, cell transfection, the dual luciferase reporter assay, western-blot, cell proliferation and trans-well based cell invasion assay were used to investigate the effects of the SNP on ErbB3 expression. Moreover, a 5-years-overall survival and relapse free survival were investigated between different genotypes.

Results

We found that patients suffering from Helicobacter pylori (Hp.) infection indicated to be the susceptible population by comparing with controls. Besides, SNP rs3202538 (G/T) in ErbB3 3′-UTR was involved in the occurrence of GC by acting as tumor risk factors. SNP rs3202538 (G/T) could be regulated by both miR-204 and miR-211 which caused an upregulation of ErbB3 in patients. Furthermore, the carriers of T genotype was related to the significantly high expression of ErbB3, and to big tumor size, poor differentiation as well as the high probability of metastasis. Both miR-211 and miR-204 can significantly decrease cell proliferation, metastasis as well as downstream AKT activation through G but not T allele of ErbB3 3′UTR. Moreover, the SNP of G/T was associated with shorter survival of post-surgery GC patients with 5 years of follow up study.

Conclusion

In conclusion, our findings have shown that the SNP rs3202538 (G/T) in ErbB3 3′-UTR acted as promotion factors in the GC development through disrupting the regulatory role of miR-204 and miR-211 in ErbB3 expression.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-017-0449-z) contains supplementary material, which is available to authorized users.

Natural Products as Chemopreventive Agents by Potential Inhibition of the Kinase Domain in ErbB Receptors

Small molecules found in natural products provide therapeutic benefits due to their pharmacological or biological activity, which may increase or decrease the expression of human epidermal growth factor receptor (HER), a promising target in the modification of signaling cascades involved in excessive cellular growth. In this study, in silico molecular protein-ligand docking protocols were performed with AutoDock Vina in order to evaluate the interaction of 800 natural compounds (NPs) from the NatProd Collection (http://www.msdiscovery.com/natprod.html), with four human HER family members: HER1 (PDB: 2ITW), HER2 (PDB: 3PP0), HER3 (PDB: 3LMG) and HER4 (PDB: 2R4B). The best binding affinity values (kcal/mol) for docking pairs were obtained for HER1-podototarin (−10.7), HER2-hecogenin acetate (−11.2), HER3-hesperidin (−11.5) and HER4-theaflavin (−10.7). The reliability of the theoretical calculations was evaluated employing published data on HER inhibition correlated with in silico binding calculations. IC₅₀ values followed a significant linear relationship with the theoretical binding Affinity data for HER1 (R = 0.656, p < 0.0001) and HER2 (R = 0.543, p < 0.0001), but not for HER4 (R = 0.364, p > 0.05). In short, this methodology allowed the identification of several NPs as HER inhibitors, being useful in the discovery and design of more potent and selective anticancer drugs.

Targeted therapies in gastric cancer and future perspectives

Advanced gastric cancer (AGC) is associated with a high mortality rate and, despite multiple new chemotherapy options, the survival rates of patients with AGC remains poor. After the discovery of targeted therapies, research has focused on the new treatment options for AGC. In the last two decades, many targeted molecules were developed against AGC. Currently, two targeted therapy molecules have been approved for patients with AGC. In 2010, trastuzumab was the first molecule shown to improve survival in patients with HER2-positive AGC as part of a first-line combination regimen. In 2014, ramucirumab was the second targeted molecule to improve survival rates and was suggested as treatment for patients with AGC who had progressed after first-line platinum plus fluoropyrimidine with or without anthracycline chemotherapy. Ramucirumab was the first targeted therapy acting as a single agent in patients with advanced gastroesophageal cancers. Although these two molecules were introduced into clinical use, many other promising molecules have been tested in phase I-II trials. It is obvious that in the near future many different targeted therapies will be in use for treatment of AGC. In this review, the current status of targeted therapies in the treatment of AGC and gastroesophageal junction tumors, including HER (2-3) inhibitors, epidermal growth factor receptor inhibitors, tyrosine kinase inhibitors, antiangiogenic agents, c-MET inhibitors, mammalian target of rapamycin inhibitors, agents against other molecular pathways fibroblast growth factor, Claudins, insulin-like growth factor, heat shock proteins, and immunotherapy, will be discussed.