PIK3CA mutations are associated with increased tumor aggressiveness and Akt activation in gastric cancer

Study of immunosenescence in the occurrence and immunotherapy of gastrointestinal malignancies

In human beings heterogenous, pervasive and lethal malignancies of different parts of the gastrointestinal (GI) tract viz., tumours of the oesophagus, stomach, small intestine, colon, and rectum, represent gastrointestinal malignancies. Primary treatment modality for gastric cancer includes chemotherapy, surgical interventions, radiotherapy, monoclonal antibodies and inhibitors of angiogenesis. However, there is a need to improve upon the existing treatment modality due to associated adverse events and the development of resistance towards treatment. Additionally, age has been found to contribute to increasing the incidence of tumours due to immunosenescence-associated immunosuppression. Immunosenescence is the natural process of ageing, wherein immune cells as well as organs begin to deteriorate resulting in a dysfunctional or malfunctioning immune system. Accretion of senescent cells in immunosenescence results in the creation of a persistent inflammatory environment or inflammaging, marked with elevated expression of pro-inflammatory and immunosuppressive cytokines and chemokines. Perturbation in the T-cell pools and persistent stimulation by the antigens facilitate premature senility of the immune cells, and senile immune cells exacerbate inflammaging conditions and the inefficiency of the immune system to identify the tumour antigen. Collectively, these conditions contribute positively towards tumour generation, growth and eventually proliferation. Thus, activating the immune cells to distinguish the tumour cells from normal cells and invade them seems to be a logical strategy for the treatment of cancer. Consequently, various approaches to immunotherapy, viz., programmed death ligand-1 (PD-1) inhibitors, Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors etc are being extensively evaluated for their efficiency in gastric cancer. In fact, PD-1 inhibitors have been sanctioned as late late-line therapy modality for gastric cancer. The present review will focus on deciphering the link between the immune system and gastric cancer, and the alterations in the immune system that incur during the development of gastrointestinal malignancies. Also, the mechanism of evasion by tumour cells and immune checkpoints involved along with different approaches of immunotherapy being evaluated in different clinical trials will be discussed.

Sotorasib resistance triggers epithelial-mesenchymal transition and activates AKT and P38-mediated signaling

Background

The molecular non-genetic changes of resistance to sotorasib are currently uncertain. The aim of this study was to generate a sotorasib-resistant cell line via selective pressure and systematically examine the molecular and phenotypic alterations caused by resistance.

Methods

Mutant NCI-H358 (KRASG12C) were exposed to incremental doses (2-512 nM) of sotorasib. Then, resistant clones were separated by single-cell sorting. Proliferation was analyzed in real-time by xCELLigence; protein profiles were quantified by protein arrays; and mRNA expression profile was measured using the PanCancer Pathways panel by NanoString. In silico analyses were conducted from a database comprising patient-derived xenograft (PDX) models and cell lines resistant to sotorasib. AKT and p38. The synergistic effect of combining AKT, p38, and EGFR inhibitors was assessed using the SynergyFinder platform. Additionally, AKT and p38 genes were silenced using esiRNA.

Results

Sotorasib-resistant H358-R cell line displayed markers of the mesenchymal-epithelial transition and loss of cell adhesion. Were identified 30 overexpressed genes in the resistance model, implicating in signaling pathways that leads to AKT activation and heightened protein expression levels of phosphorylated AKT and p38. To identify potential therapeutic strategies for overcoming sotorasib resistance, we investigated the combination of AKT and p38 inhibitors. Notably, combined inhibition of AKT (MK2206) and p38 (adezmapimod) restored sensitivity to sotorasib in resistant cell lines, as did silencing AKT expression.

Conclusion

These findings underscore the importance of adaptive mechanisms in sotorasib resistance in NSCLC cells contributing by EMT activation and demonstrates synergic combination with AKT and p38 inhibitors to restore sotorasib sensitivity in KRASG12C cells.

EGFR and PI3K Signalling Pathways as Promising Targets on Circulating Tumour Cells from Patients with Metastatic Gastric Adenocarcinoma

The prognosis for metastatic gastric adenocarcinoma (mGAC) remains poor. Gene alterations in receptor tyrosine kinases (RTKs) such as epidermal growth factor receptor (EGFR) and their downstream effectors including catalytic subunit alpha of the phosphatidylinositol 3-kinase (PIK3CA) are common in mGAC. Targeted RTK and phosphatidylinositol-3-kinase (PI3K) treatments have demonstrated clinical benefits in other solid tumours and are key potential targets for clinical development against mGAC given the presence of recurrent alterations in these pathways. Furthermore, combination RTK/PI3K treatments may overcome compensatory mechanisms that arise using monotherapies, leading to improved patient outcomes. Herein, we investigated RTK/PI3K single and combination drug responses against our unique human mGAC-derived PIK3CA gain-of-function mutant, human epidermal growth factor receptor 2 (HER2)-negative, EGFR-expressing circulating tumour cell line, UWG02CTC, under two- and three-dimensional culture conditions to model different stages of metastasis. UWG02CTCs were highly responsive to the PI3K p110α-subunit targeted drugs PIK-75 (IC50 = 37.0 ± 11.1 nM) or alpelisib (7.05 ± 3.7 µM). Drug sensitivities were significantly increased in 3D conditions. Compensatory MAPK/ERK pathway upregulation by PI3K/Akt suppression was overcome by combination treatment with the EGFR inhibitor gefitinib, which was strongly synergistic. PIK-75 plus gefitinib significantly impaired UWG02CTC invasion in an organotypic assay. In conclusion, UWG02CTCs are a powerful ex vivo mGAC drug responsiveness model revealing EGFR/PI3K-targeted drugs as a promising combination treatment option for HER2-negative, RAS wild-type mGAC patients.

Molecular Classifications in Gastric Cancer: A Call for Interdisciplinary Collaboration

Gastric cancer (GC) is a heterogeneous disease, often diagnosed at advanced stages, with a 5-year survival rate of approximately 20%. Despite notable technological advancements in cancer research over the past decades, their impact on GC management and outcomes has been limited. Numerous molecular alterations have been identified in GC, leading to various molecular classifications, such as those developed by The Cancer Genome Atlas (TCGA) and the Asian Cancer Research Group (ACRG). Other authors have proposed alternative perspectives, including immune, proteomic, or epigenetic-based classifications. However, molecular stratification has not yet transitioned into clinical practice for GC, and little attention has been paid to alternative molecular classifications. In this review, we explore diverse molecular classifications in GC from a practical point of view, emphasizing their relationships with clinicopathological factors, prognosis, and therapeutic approaches. We have focused on classifications beyond those of TCGA and the ACRG, which have been less extensively reviewed previously. Additionally, we discuss the challenges that must be overcome to ensure their impact on patient treatment and prognosis. This review aims to serve as a practical framework to understand the molecular landscape of GC, facilitate the development of consensus molecular categories, and guide the design of innovative molecular studies in the field.

A Five-gene Signature based on MicroRNA for Predicting Prognosis and Immunotherapy in Stomach Adenocarcinoma

AIMS

We aimed to classify molecular subtypes and establish a prognostic gene signature based on miRNAs for the prognostic prediction and therapeutic response in Stomach adenocarcinoma (STAD).

BACKGROUND

STAD is a common diagnosed gastrointestinal malignancy and its heterogeneity is a big challenge that influences prognosis and precision therapies. Present study was designed to classify molecular subtypes and construct a prognostic gene signature based on miRNAs for the prognostic prediction and therapeutic response in STAD.

OBJECTIVE

The objective of this study is to investigate the molecular subtypes and prognostic model for STAD.

METHODS

A STAD specific miRNA-messenger RNA (mRNA) competing endogenous RNA (ceRNA) network was generated using the RNA-Seq and miRNA expression profiles from The Cancer Genome Atlas (TCGA) database, in which miRNA-related mRNAs were screened. Molecular subtypes were then determined using miRNA-related genes. Through univariate Cox analysis and multivariate regression analysis, a prognostic model was established in GSE84437 Train dataset and validated in GSE84437 Test, TCGA, GSE84437 and GSE66229 datasets. Immunotherapy datasets were employed for assessing the performance of the risk model. Finally, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was applied to validate the expression of hub genes used for the risk score signature.

RESULTS

We constructed a ceRNA network containing 84 miRNAs and 907 mRNAs and determined two molecular subtypes based on 26 genes from the intersection of TCGASTAD and GSE84437 datasets. Subtype S2 had poor prognosis, lower tumor mutational burden, higher immune score and lower response to immunotherapy. Subtype S1 was more sensitive to Sorafenib, Pyrimethamine, Salubrinal, Gemcitabine, Vinorelbine and AKT inhibitor VIII. Next, a five-gene signature was generated and its robustness was validated in Test and external datasets. This risk model also had a good prediction performance in immunotherapy datasets.

CONCLUSION

This study promotes the underlying mechanisms of miRNA-based genes in STAD and offers directions for classification. A five-gene signature accurately predicts the prognosis and helps therapeutic options.

CBF-Beta Mitigates PI3K-Alpha-Specific Inhibitor Killing through PIM1 in PIK3CA-Mutant Gastric Cancer

PIK3CA is the second most mutated gene in cancer leading to aberrant PI3K/AKT/mTOR signaling and increased translation, proliferation, and survival. Some 4%-25% of gastric cancers display activating PIK3CA mutations, including 80% of Epstein-Barr virus-associated GCs. Small molecules, including pan-PI3K and dual PI3K/mTOR inhibitors, have shown moderate success clinically, due to broad on-target/off-tissue effects. Thus, isoform-specific and mutant selective inhibitors have been of significant interest. However, drug resistance is a problem and has affected success of new drugs. There has been a concerted effort to define mechanisms of resistance and identify potent combinations in many tumor types, though gastric cancer is comparatively understudied. In this study, we identified modulators of the response to the PI3Kα-specific inhibitor, BYL719, in PIK3CA-mutant GCs. We found that loss of NEDD9 or inhibition of BCL-XL conferred hypersensitivity to BYL719, through increased cell-cycle arrest and cell death, respectively. In addition, we discovered that loss of CBFB conferred resistance to BYL719. CBFB loss led to upregulation of the protein kinase PIM1, which can phosphorylate and activate several overlapping downstream substrates as AKT thereby maintaining pathway activity in the presence of PI3Kα inhibition. The addition of a pan-PIM inhibitor re-sensitized resistant cells to BYL719. Our data provide clear mechanistic insights into PI3Kα inhibitor response in PIK3CA-mutant gastric tumors and can inform future work as mutant-selective inhibitors are in development for diverse tumor types.

IMPLICATIONS

Loss of either NEDD9 or BCL-XL confers hypersensitivity to PI3K-alpha inhibition whereas loss of CBFB confers resistance through a CBFB/PIM1 signaling axis.

Advancement in precision diagnosis and therapeutic for triple-negative breast cancer: Harnessing diagnostic potential of CRISPR-cas & engineered CAR T-cells mediated therapeutics

Cancer is characterized by uncontrolled cell growth, disrupted regulatory pathways, and the accumulation of genetic mutations. These mutations across different types of cancer lead to disruptions in signaling pathways and alterations in protein expression related to cellular growth and proliferation. This review highlights the AKT signaling cascade and the retinoblastoma protein (pRb) regulating cascade as promising for novel nanotheranostic interventions. Through synergizing state-of-the-art gene editing tools like the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas system with nanomaterials and targeting AKT, there is potential to enhance cancer diagnostics significantly. Furthermore, the integration of modified CAR-T cells into multifunctional nanodelivery systems offers a promising approach for targeted cancer inhibition, including the eradication of cancer stem cells (CSCs). Within the context of highly aggressive and metastatic Triple-negative Breast Cancer (TNBC), this review specifically focuses on devising innovative nanotheranostics. For both pre-clinical and post-clinical TNBC detection, the utilization of the CRISPR-Cas system, guided by RNA (gRNA) and coupled with a fluorescent reporter specifically designed to detect TNBC's mutated sequence, could be promising. Additionally, a cutting-edge approach involving the engineering of TNBC-specific iCAR and syn-Notch CAR T-cells, combined with the co-delivery of a hybrid polymeric nano-liposome encapsulating a conditionally replicative adenoviral vector (CRAdV) against CSCs, could present an intriguing intervention strategy. This review thus paves the way for exciting advancements in the field of nanotheranostics for the treatment of TNBC and beyond.

AKT-independent signaling in PIK3CA-mutant thyroid cancer mediates resistance to dual SRC and MEK1/2 inhibition

Anaplastic thyroid cancer (ATC) is a rare and aggressive disease with 90% of patients succumbing to this disease 1 year after diagnosis. The approval of the combination therapy of a BRAF inhibitor dabrafenib with the MEK1/2 inhibitor trametinib has improved the overall survival of ATC patients. However, resistance to therapy remains a major problem. We have previously demonstrated combined inhibition of Src with dasatinib and MEK1/2 with trametinib synergistically inhibits growth and induces apoptosis in BRAF- and RAS-mutant thyroid cancer cells, however PIK3CA-mutant cells exhibit a mixed response. Herein, we determined that AKT is not a major mediator of sensitivity and instead PIK3CA-mutants that are resistant to combined dasatinib and trametinib have sustained activation of PDK1 signaling. Furthermore, combined inhibition of PDK1 and MEK1/2 was sufficient to reduce cell viability. These data indicate PDK1 inhibition is a therapeutic option for PIK3CA mutations that do not respond to combined Src and MEK1/2 inhibition.

A consolidated working classification of gastric cancer for histopathologists (Review)

Gastric cancer (GC) remains a disease with poor prognosis despite increasing availability of more effective targeted treatment. This may be in part due to the difficulty in selecting patients for appropriate treatment. Conventional taxonomic classifications of GC are ill-suited to make full use of recent advances in personalised therapy. In the past decade a number of molecular classifications have been proposed to address this; however, to date, there has been little implementation in the diagnostic routine. The lack of harmonisation between these classifications, the complexity and unavailability of some of the tests required plus the demands on time and resources, all contribute to poor uptake in the diagnostic routine. In the present study, these classifications were reviewed and an inclusive working classification that includes their main points, focuses on prognosis and treatment options and can be delivered using four on-slide tests (in situ hybridization for Epstein-Barr encoding region and immunohistochemistry for mismatch repair, E-cadherin and p53) is proposed. These tests can be performed on paraffin-embedded tissue and could be available in the majority of histopathology laboratories. The proposed classification also includes reflex testing for specific biomarkers relevant to treatment selection.

KRAS mutation as a predictor of insufficient trastuzumab efficacy and poor prognosis in HER2-positive advanced gastric cancer

PURPOSE

Although RAS and PIK3CA mutations have been associated with resistance to anti-EGFR antibody in colorectal cancer or trastuzumab in breast cancer, their implications for trastuzumab resistance in HER2-positive advanced gastric cancer (AGC) remains unclear. We aimed to assess the relationship between trastuzumab efficacy and mutation status in the HER family signaling pathway.

METHODS

This study retrospectively evaluated patients with HER2-positive AGC who received first-line trastuzumab-containing chemotherapy between March 2011 and November 2015. Multiplex genotyping, including KRAS, NRAS, PIK3CA, and BRAF, was then performed using the Luminex Assay, after which KRAS amplification was measured using quantitative real-time reverse transcription-polymerase chain reaction. Thereafter, the association between genetic alterations and clinical outcomes were evaluated.

RESULTS

KRAS mutation (MT) was detected in 6 of 77 patients (7.8%), whereas KRAS amplification was found in 15 of 67 patients (22%). No mutations in NRAS, PIK3CA, or BRAF were identified. The KRAS MT group showed significantly worse response rates (16.7% vs. 66.2%, P = 0.016), progression-free survival [median, 4.8 vs. 11.6 months; hazard ratio (HR), 3.95; 95% CI, 1.60-9.76; P = 0.0029], and overall survival (11.5 vs. 23.6 months; HR, 3.80; 95% CI, 1.56-9.28; P = 0.033) compared to the KRAS wild-type group. KRAS amplification had no effect on clinical outcomes.

CONCLUSION

KRAS mutation was an independent prognostic factor for poor survival and might predict insufficient trastuzumab efficacy, whereas KRAS amplification showed no prognostic significance during trastuzumab treatment. Further investigations are warranted to confirm the predictive value of KRAS status in HER2-positive AGC.

Identification and Verification of Potential Biomarkers in Gastric Cancer By Integrated Bioinformatic Analysis

Background: Gastric cancer (GC) is a common cancer with high mortality. This study aimed to identify its differentially expressed genes (DEGs) using bioinformatics methods.

Methods: DEGs were screened from four GEO (Gene Expression Omnibus) gene expression profiles. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed. A protein–protein interaction (PPI) network was constructed. Expression and prognosis were assessed. Meta-analysis was conducted to further validate prognosis. The receiver operating characteristic curve (ROC) was analyzed to identify diagnostic markers, and a nomogram was developed. Exploration of drugs and immune cell infiltration analysis were conducted.

Results: Nine up-regulated and three down-regulated hub genes were identified, with close relations to gastric functions, extracellular activities, and structures. Overexpressed Collagen Type VIII Alpha 1 Chain (COL8A1), Collagen Type X Alpha 1 Chain (COL10A1), Collagen Triple Helix Repeat Containing 1 (CTHRC1), and Fibroblast Activation Protein (FAP) correlated with poor prognosis. The area under the curve (AUC) of ADAM Metallopeptidase With Thrombospondin Type 1 Motif 2 (ADAMTS2), COL10A1, Collagen Type XI Alpha 1 Chain (COL11A1), and CTHRC1 was >0.9. A nomogram model based on CTHRC1 was developed. Infiltration of macrophages, neutrophils, and dendritic cells positively correlated with COL8A1, COL10A1, CTHRC1, and FAP. Meta-analysis confirmed poor prognosis of overexpressed CTHRC1.

Conclusion: ADAMTS2, COL10A1, COL11A1, and CTHRC1 have diagnostic values in GC. COL8A1, COL10A1, CTHRC1, and FAP correlated with worse prognosis, showing prognostic and therapeutic values. The immune cell infiltration needs further investigations.

Systematic Review and Meta-analysis of TP53, HER2/ERBB2, KRAS, APC, and PIK3CA Genes Expression Pattern in Gastric Cancer

Background: With a global prevalence of about 10%, gastric cancer is among the most prevalent cancers. Currently, there has been an ongoing trend toward investigating genetic disruptions in different cancers because they can be used as a target-specific therapy. We aimed to systemically review some gene expression patterns in gastric cancer. Methods: The current systematic review was designed and executed in 2020. Scopus, PubMed, Cochrane Library, Google Scholar, web of knowledge, and Science Direct were searched for relevant studies. A manual search of articles (hand searching), reference exploring, checking for grey literature, and seeking expert opinion were also done. Results: In this review, 65 studies were included, and the expression pattern of HER2/ ERBB2, ER1/Erb1/EGFR, PIK3CA, APC, KRAS, ARID1A, TP53, FGFR2 and MET was investigated. TP53, APC, KRAS, and PIK3CA mutation cumulative frequency were 24.8 (I²=95.05, Q value=525.53, df=26, P<0.001), 7.2 (I²=89.79, Q value=48.99, df=5, P<0.001), 7.8 (I²=93.60, Q value=140.71, df=9, P=0.001) and 8.6 (I²=80.78, Q value=525.53, df=9, P<0.001) percent, respectively. Overexpression was investigated for HER1/ Erb1/EGFR, PIK3CA, APC, KRAS, ARID1A, TP53, CCND1, FGFR2, MET and MYC. The frequency of TP53 and HER2/ERBB2 were 43.1 (I²=84.06, Q value=58.09, df=9, P<0.001) and 20.8 (I²=93.61, Q value=234.89, df=15, P<0.001) percent, respectively. Conclusion: More research is encouraged to investigate the genes for which we could not perform a meta-analysis.

Tumor Molecular Profiling in Hispanics: Moving Towards Precision Oncology and Health Equity

BACKGROUND

Tumor molecular profiling techniques, such as next-generation sequencing (NGS) to identify somatic genetic alterations, allow physicians to have a better understanding of the affected carcinogenic pathways and guide targeted therapy. The objective of our study was to characterize common somatic alterations and carcinogenic pathways among Puerto Rican Hispanics with solid tumors.

METHODS

We conducted a single-institution, retrospective study to characterize molecular tumor profiles using a 592-gene NGS platform. Actionable mutations with current or developing therapies targeting affected genes/pathways were highlighted.

RESULTS

Tumors from 50 Hispanic patients were evaluated using CARIS Life Science© NGS testing. The median age of our study population was 55 (range 21-84); 54% (n = 27) were males. The primary tumor sites were colorectal (n = 24), gastric (n = 5), breast (n = 4), and lung (n = 3). The most common genetic mutations identified were in TP53 (44%), APC (38%), and KRAS (32%); followed by alterations in EGFR (4%), HER2 (6%), and homologous recombinant deficiency genes (BRCA2, 6%). Genetic alterations were found in multiple signaling pathways particularly in the cell cycle control pathway, MAPK and Wnt/β-Catenin signaling pathways. Targetable biomarkers were identified in 27/50 (54.0%) of tumors.

DISCUSSION

Molecular profiling techniques, such as next-generation sequencing, have substantially expanded access to alterations in the cancer genome. Our findings demonstrated important actionable mutations in most of the tumors evaluated and support the integration of somatic mutation profiling in the evaluation of Hispanic cancer patients with advanced cancer to help guide therapeutic options.

AKT Isoforms in the Immune Response in Cancer

AKT is a protein kinase that exists in three isoforms: AKT1, AKT2, and AKT3. Though similar in structure, these isoforms display different effects. AKT is activated downstream of PI3K, and together, this signaling pathway helps regulate cellular processes including cell growth, proliferation, metabolism, survival, and apoptosis. Disruption in these pathways has been associated with disorders including cardiovascular diseases, developmental disorders, inflammatory responses, autoimmune diseases, neurologic disorders, type 2 diabetes, and several cancers. In cancer, deregulation in the PI3K/AKT pathway can be manifested as tumorigenesis, pathological angiogenesis, and metastasis. Increased activity has been correlated with tumor progression and resistance to cancer treatments. Recent studies have suggested that inhibition of the PI3K/AKT pathway plays a significant role in the development, expansion, and proliferation of cells of the immune system. Additionally, AKT has been found to play an important role in differentiating regulatory T cells, activating B cells, and augmenting tumor immunosurveillance. This emphasizes AKT as a potential target for inhibition in cancer therapy. This chapter reviews AKT structure and regulation, its different isoforms, its role in immune cells, and its modulation in oncotherapy.

Identification and Validation of PIK3CA as a Marker Associated with Prognosis and Immune Infiltration in Renal Clear Cell Carcinoma

Background

Kidney renal clear cell carcinoma (KIRC) is the most prevalent renal malignancy. The therapeutic strategies for advanced KIRC are very few, with only sunitinib being widely approved. Mutations in the PIK3CA gene can affect tumor cell proliferation, metastasis, and patients' survival.

Methods

Bioinformatics analysis was performed to explore the expression and clinical significance of PIK3CA in KIRC. Moreover, qRT-PCR was conducted to verify the result.

Results

Subgroup analyses of KIRC tissue based on gender, tumor grade, and cancer stage indicated downregulation of PIK3CA mRNA expression. The KIRC patients with high PIK3CA expression indicated a better overall survival, progression-free survival, and disease-free survival. A predictive nomogram was constructed and demonstrated that the calibration plots for the 3-year and 5-year OS rates were predicted relatively well compared with an ideal model in the TCGA KIRC cohort. The validation study revealed that downregulation of PIK3CA in KIRC tissues and low PIK3CA expression had a poor overall survival with an AUC of 0.775 in the ROC curve. Moreover, Cox regression analysis revealed that PIK3CA expression and clinical stage were independent factors affecting the prognosis of KIRC patients. PIK3CA expression was found to be significantly associated with the abundance of immune cells and immune biomarker sets. PIK3CA and associated genes were found to be mainly associated with immune response and the JAK-STAT signaling pathway.

Conclusion

We identified PIK3CA as a potential biomarker for prognosis correlated with immune infiltrates in KIRC. Further studies should focus on the functions of PIK3CA in KIRC carcinogenesis.

Research status on immunotherapy trials of gastric cancer

The breakthrough of immune checkpoint inhibitor (ICI) therapy has created extensive opportunities for cancer immunotherapy. Especially, the block of programmed death-1/programmed death ligand 1 (PD-L1) axis using ICIs has become a new therapeutic strategy to treat advanced gastric cancer (GC). However, in the past decade, single-arm and randomized trials for single-drug ICI therapy showed that the therapeutic effect was not satisfactory, including clinical trials for advanced GC. However, after selecting suitable predictive biomarkers and developing a combination of anti-angiogenic targeted drugs and other chemotherapeutic drugs, the objective response rate and progression-free survival of patients with gastric cancer were improved significantly. The United States Food and Drug Administration has approved treatment with pembrolizumab for patients with advanced GC with PD-L1 expression or microsatellite instability-high/mismatch repair deficiency. In this review, the updated data from the latest trial results of combination immunotherapy for GC are presented. Based on the outcome of combination therapy, we discuss its possible molecular mechanism and summarize effective predictive biomarkers. We also discuss possible problems stemming from results of other clinical trials of ICI treatment and propose other directions for ICI therapy.

Mutations of key driver genes in gastric cancer metastasis risk: a systematic review and meta-analysis

Objective: Associations between gene mutations and metastasis in gastric cancer (GC) remain contradictory, resulting in the inaccurate estimation of the magnitude of the risk associated with specific genotypes.Methods: In this study, we first screened out four key driver genes (TP53, PIK3CA, APC and ARID1A) by jointly analyzing the mutation levels and searching the literature for genes associated with GC metastasis. We then performed a meta-analysis to demonstrate the relationship between these key driver gene mutations and GC metastasis, including lymphatic and distance metastasis.Results: We found out four key driver genes (TP53, PIK3CA, APC and ARID1A), associated with risk of GC metastasis. The results showed that TP53 (OR 1.39, 95% CI 1.12-1.72) and APC mutations (OR 0.58, 95% CI 0.38-0.89) were associated with lymph node metastasis and distant metastasis in GC. And TP53 mutations (OR 1.65, 95% CI 1.25-2.18) were significantly related to GC metastasis in the Asian population. APC mutations (OR 0.54, 95% CI 0.29-1.00) were also related to GC metastasis in the European and American populations. There was no significant association with GC metastasis in PIK3CA or ARID1A mutations.Expert opinion:Mutations of TP53 and APC play important roles in lymph node metastasis and distant metastasis of GC and may be potential important biomarkers of progression and therapeutic targets. These observations should be further prospectively verified.

Development and Validation of a Prognostic Classifier Based on Lipid Metabolism-Related Genes in Gastric Cancer

Background: Dysregulation of lipid metabolism plays important roles in the tumorigenesis and progression of gastric cancer (GC). The present study aimed to establish a prognostic model based on the lipid metabolism–related genes in GC patients.

Materials and Methods: Two GC datasets from the Gene Expression Atlas, GSE62254 (n = 300) and GSE26942 (n = 217), were used as training and validation cohorts to establish a risk predictive scoring model. The efficacy of this model was assessed by ROC analysis. The association of the risk predictive scores with patient characteristics and immune cell subtypes was evaluated. A nomogram was constructed based on the risk predictive score model and other prognostic factors.

Results: A risk predictive score model was established based on the expression of 19 lipid metabolism–related genes (LPL, IPMK, PLCB3, CDIPT, PIK3CA, DPM2, PIGZ, GPD2, GPX3, LTC4S, CYP1A2, GALC, SGMS1, SMPD2, SMPD3, FUT6, ST3GAL1, B4GALNT1, and ACADS). The time-dependent ROC analysis revealed that the risk predictive score model was stable and robust. Patients with high risk scores had significantly unfavorable overall survival compared with those with low risk scores in both the training and validation cohorts. A higher risk score was associated with more aggressive features, including a higher tumor grade, a more advanced TNM stage, and diffuse type of Lauren classification of GC. Moreover, distinct immune cell subtypes and signaling pathways were found between the high–risk and low–risk score groups. A nomogram containing patients’ age, tumor stage, adjuvant chemotherapy, and the risk predictive score could accurately predict the survival probability of patients at 1, 3, and 5 years.

Conclusion: A novel 19-gene risk predictive score model was developed based on the lipid metabolism–related genes, which could be a potential prognostic indicator and therapeutic target of GC.

Biological Role of AKT and Regulation of AKT Signaling Pathway by Thymoquinone: Perspectives in Cancer Therapeutics

BACKGROUND

AKT/PKB is an important enzyme with numerous biological functions, and its overexpression is related to carcinogenesis. AKT stimulates different signaling pathways that are downstream of activated tyrosine kinases and phosphatidylinositol 3-kinase, hence functions as an important target for anti-cancer drugs.

OBJECTIVE

In this review article, we have interpreted the role of AKT signaling pathway in cancer and the natural inhibitory effect of Thymoquinone (TQ) in AKT and its possible mechanisms.

METHOD

We have collected the updated information and data on AKT, its role in cancer and the inhibitory effect of TQ in AKT signaling pathway from Google Scholar, PubMed, Web of Science, Elsevier, Scopus, and many more.

RESULTS

Many drugs are already developed, which can target AKT, but very few among them have passed clinical trials. TQ is a natural compound, mainly found in black cumin, which has been found to have potential anti-cancer activities. TQ targets numerous signaling pathways, including AKT, in different cancers. In fact, many studies revealed that AKT is one of the major targets of TQ. The preclinical success of TQ suggests its clinical studies on cancer.

CONCLUSION

This review article summarizes the role of AKT in carcinogenesis, its potent inhibitors in clinical trials, and how TQ acts as an inhibitor of AKT and TQ's future as a cancer therapeutic drug.

The PI3K/Akt/mTOR signaling pathway in gastric cancer; from oncogenic variations to the possibilities for pharmacologic interventions

Genetic and epigenetic alterations have been under concentrated investigations for many years in order to unearth the molecules regulating human cancer pathogenesis. However, the identification of a wide range of dysregulated genes and their protein products has raised a question regarding how the results of this large collection of alterations could converge into a formation of one malignancy. The answer may be found in the signaling cascades that regulate the survival and metabolism of the cells. Aberrancies of each participant molecule of such cascades may well result in augmented viability and unlimited proliferation of cancer cells. Among various signaling pathways, the phosphatidylinositol-3-kinase (PI3K) axis has been shown to be activated in about one-third of human cancers. One of the malignancies that is mostly affected by this axis is gastric cancer (GC), one of the most fatal cancers worldwide. In the present review, we aimed to illustrate the significance of the PI3K/Akt/mTOR axis in the pathogenesis of GC and also provided a wide perspective about the application of the inhibitors of this axis in the therapeutic strategies of this malignancy.

Mutational drivers of cancer cell migration and invasion

Genomic instability and mutations underlie the hallmarks of cancer-genetic alterations determine cancer cell fate by affecting cell proliferation, apoptosis and immune response, and increasing data show that mutations are involved in metastasis, a crucial event in cancer progression and a life-threatening problem in cancer patients. Invasion is the first step in the metastatic cascade, when tumour cells acquire the ability to move, penetrate into the surrounding tissue and enter lymphatic and blood vessels in order to disseminate. A role for genetic alterations in invasion is not universally accepted, with sceptics arguing that cellular motility is related only to external factors such as hypoxia, chemoattractants and the rigidity of the extracellular matrix. However, increasing evidence shows that mutations might trigger and accelerate the migration and invasion of different types of cancer cells. In this review, we summarise data from published literature on the effect of chromosomal instability and genetic mutations on cancer cell migration and invasion.

Integrating Network Pharmacology and Experimental Validation to Investigate the Mechanisms of Huazhuojiedu Decoction to Treat Chronic Atrophic Gastritis

Background

Chronic atrophic gastritis (CAG) is an important stage in the normal gastric mucosa's transformation into gastric cancer. Huazhuojiedu decoction (HZJD), a Chinese herbal preparation, has proven clinically effective to treat CAG. However, few studies have explored the mechanism of HZJD in CAG treatment.

Purpose

This study aimed to shed light on the mechanisms underlying HZJD decoction CAG treatment using a network pharmacology approach and experimental validation.

Methods

The active components of HZJD decoction were obtained from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform. Their targets were predicted through the SwissTargetPrediction database. Disease targets were screened using the GeneCards database. The disease and drug prediction targets were intersected to select the common potential therapeutic targets, which then were input into the Search Tool for the Retrieval of Interacting Genes to build a protein-protein interaction network. The “herb-compound-target-disease” and the “herb-target-pathway” network diagrams were constructed in Cytoscape 3.3.0. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis of effective targets were performed using the Database for Annotation, Visualization, and Integrated Discovery. Finally, the core targets were preliminarily verified by CAG rat model. The gastric mucosa's histopathological changes were observed via hematoxylin-eosin staining. The expressions of MAPK1, AKT1, TNF, VEGFA, and EGFR were detected by western blot and quantitative real-time reverse transcription-polymerase chain reaction.

Results

A total of 155 nodes, including 20 putative targets of HZJD decoction, were selected as core hubs based on topological importance and were closely associated with the regulation of cell proliferation, apoptotic process, and cancer-related pathways (AKT1, TNF, VEGFA, and EGFR) in CAG. Further animal experiments showed that the expression of AKT1 in CAG rats was significantly increased, which was suppressed by HZJD decoction. TNF and VEGFA expression increased in the model group, but did not change in the HZJD group. MAPK1 and EGFR expression showed no significant differences among control, model, and HZJD groups.

Conclusion

Taken together, the results suggest that the components of HZJD decoction can alleviate and prevent the severity of gastric precancerous lesions via AKT1 inhibition in CAG.

Genetic profiling of somatic alterations by Oncomine Focus Assay in Korean patients with advanced gastric cancer

Gastric cancer is one of the leading causes of cancer-associated death; however, analysis of its molecular and clinical characteristics has been complicated by its histological and etiological heterogeneity. The present study aimed to estimate somatic mutation profiling in gastric cancer. To do so, targeted next-generation sequencing (NGS) was performed with the Oncomine Focus Assay to compare the clinicopathological characteristics with the mutation profiles in 50 patients with advanced gastric cancer (AGC). Among the 35 hotspot genes and 19 genes for copy number variations (CNVs), 18 single nucleotide variants (SNVs) or small insertions and deletions (14 missense and four frameshift mutations), and 10 amplifications were identified. To examine the association between mutation profiles and clinicopathological characteristics, each element of the clinicopathological characteristics was categorized into three groups: No alteration, PI3K catalytic subunit α (PIK3CA) alterations and alterations other than PIK3CA. Fisher's exact test identified no statistical differences between the clinicopathological characteristics, with the exception of the Tumor-Node-Metastasis (TNM) T stage between the three groups. Cases of AGC with somatic alterations but no PIK3CA exhibited a significant difference in the TNM T stage compared with those with no alterations or PIK3CA alterations (P=0.044). In addition, AGC with PIK3CA alterations was categorized by Lauren's classification to the intestinal type only. The distribution of Lauren's classification in AGC with PIK3CA alterations was statistically different compared with AGC with alterations other than PIK3CA (P=0.028), but not compared with AGC with no alterations (P=0.076). In conclusion, the present study demonstrated a molecular profiling approach that identified potential molecular classifications for gastric cancer and suggested a framework for precision medicine in AGC.

PI3K-targeting strategy using alpelisib to enhance the antitumor effect of paclitaxel in human gastric cancer

PIK3CA mutations are frequently observed in various human cancers including gastric cancer (GC). This study was conducted to investigate the anti-tumor effects of alpelisib, a PI3K p110α-specific inhibitor, using preclinical models of GC. In addition, the combined effects of alpelisib and paclitaxel on GC were evaluated. Among the SNU1, SNU16, SNU484, SNU601, SNU638, SNU668, AGS, and MKN1 GC cells, three PIK3CA-mutant cells were predominantly sensitive to alpelisib. Alpelisib monotherapy decreased AKT and S6K1 phosphorylation and induced G₀/G₁ phase arrest regardless of PIK3CA mutational status. The alpelisib and paclitaxel combination demonstrated synergistic anti-proliferative effects, preferentially on PIK3CA-mutant cells, resulting in increased DNA damage response and apoptosis. In addition, alpelisib and paclitaxel combination potentiated anti-migratory activity in PIK3CA-mutant cells. Alpelisib partially reversed epithelial–mesenchymal transition markers in PIK3CA-mutant cells. In a xenograft model of MKN1 cells, the alpelisib and paclitaxel combination significantly enhanced anti-tumor activity by decreasing Ki-67 expression and increasing apoptosis. Moreover, this combination tended to prolong the survival of tumor-bearing mice. Our data suggest promising anti-tumor efficacy of alpelisib alone or in combination with paclitaxel in PIK3CA-mutant GC cells.

Current status of immune checkpoint inhibitors for gastric cancer

Recent breakthrough results from immune checkpoint inhibitors (ICI) have paved the way to a new era of cancer immunotherapy. In particular, inhibition of programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) axis with ICI including nivolumab and pembrolizumab has been emerging as a novel treatment strategy for advanced gastric cancers (GC). In a meta-analysis for anti-PD-1/PD-L1 therapy in GC, the objective response rate was 12.0% and the disease control ratio was 34.7%. The ICI treatment in GC provided modest survival benefit and especially, anti-PD-1 treatment could improve the 12-month and 18-month overall survival rate and prolonged the duration of the response. Moreover, it is likely that anti-PD-1/PD-L1 therapy is more effective in subgroups with microsatellite instability-high, Epstein-Barr virus-positive or high mutation burden in advanced GC. The next steps for developing ICI in GC are mainly two challenges as follows. First is the identification of accurate biomarkers that can predict the response to ICI. The second challenge is the clinical development of combinatorial approaches to maximize the efficacy of ICI. In this review, recent advances in ICI for GC are discussed from a viewpoint of translational aspect including biomarkers and tumor microenvironment, and from a viewpoint of clinical aspects including combination therapies.

Study on the mechanisms of compound Kushen injection for the treatment of gastric cancer based on network pharmacology

Background

As an effective prescription for gastric cancer (GC), Compound Kushen Injection (CKI) has been widely used even though few molecular mechanism analyses have been carried out.

Methods

In this study, we identified 16 active ingredients and 60 GC target proteins. Then, we established a compound-predicted target network and a GC target protein-protein interaction (PPI) network by Cytoscape 3.5.1 and systematically analyzed the potential targets of CKI for the treatment of GC. Finally, molecular docking was applied to verify the key targets. In addition, we analyzed the mechanism of action of the predicted targets by Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses.

Results

The results showed that the potential targets, including CCND1, PIK3CA, AKT1, MAPK1, ERBB2, and MMP2, are the therapeutic targets of CKI for the treatment of GC. Functional enrichment analysis indicated that CKI has a therapeutic effect on GC by synergistically regulating some biological pathways, such as the cell cycle, pathways in cancer, the PI3K-AKT signaling pathway, the mTOR signaling pathway, and the FoxO signaling pathway. Moreover, molecular docking simulation indicated that the compounds had good binding activity to PIK3CA, AKT1, MAPK1, ERBB2, and MMP2 in vivo.

Conclusion

This research partially highlighted the molecular mechanism of CKI for the treatment of GC, which has great potential in the identification of the effective compounds in CKI and biomarkers to treat GC.

Unraveling the Heterogeneous Mutational Signature of Spontaneously Developing Tumors in MLH1-/- Mice

Mismatch repair deficient (MMR-D) tumors exemplify the prototypic hypermutator phenotype. Owing to the high mutation rates, plenty of neo-antigens are present on the tumor cells' surface, ideally shared among different cancer types. The MLH1 knock out mouse represents a preclinical model that resembles features of the human MMR-D counterpart. While these mice develop neoplasias in a sequential twin-peaked manner (lymphomas > gastrointestinal tumors (GIT)) we aimed at identification of underlying molecular mechanisms. Using whole-genome sequencing, we focused on (I) shared and (II) mutually exclusive mutations and describe the process of ongoing mutational events in tumor-derived cell cultures. The landscape of MLH1^-/- tumors is heterogeneous with only a few shared mutations being detectable among different tumor entities (ARID1A and IDH2). With respect to coding microsatellite analysis of MMR-D-related target genes, partial overlap was detectable, yet recognizing shared antigens. The present study is the first reporting results of a comparison between spontaneously developing tumors in MMR-D driven tumorigenesis. Additionally to identifying ARID1A as potential causative mutation hotspot, this comprehensive characterization of the mutational landscape may be a good starting point to refine therapeutic concepts.

Associations of PIK3CA mutations with clinical features and prognosis in gastric cancer

Aim: The clinical implications of PIK3CA mutations in gastric cancer (GC) are not conclusive. Materials & methods: A systematic searching of the previous publications and related studies in The Cancer Genome Atlas (TCGA) database were performed to investigate the clinical implications of PIK3CA mutations in GC.  Results: Twenty-six independent cohort studies including six studies with original data were identified. Meta-analysis suggested PIK3CA mutations were associated with high T stage, poor differentiation and microsatellite instability, but not with prognosis in overall. However, PIK3CA mutation was found to be associated with favorable overall survival in subgroup of patients with low PIK3CA mutation prevalence. Conclusion: PIK3CA mutations might be involved in GC development and might be used as favorable prognostic factor in GC population with low PIK3CA mutations prevalence.

CCNE1 amplification is associated with liver metastasis in gastric carcinoma

With targeted therapies becoming the new standard of care in oncology, next generation sequencing (NGS) is emerging as a valuable method for analyzing the molecular underpinnings of individual tumors. Cyclin E1, encoded by CCNE1 causes activation of E2F mediated transcription and drives cells from G1 into S phase with cyclin-dependent kinase 2 (CDK2). CCNE1 amplification has been found in 11-12% of gastric cancers, but the clinical significance of this amplification remains controversial, and its association with liver metastasis has not been studied. This study included 226 patients diagnosed with advanced gastric adenocarcinoma. We performed multi-gene panel tests containing 143 genes using DNA and RNA obtained from primary (n = 197; 120 endoscopic biopsies and 77 resections) or metastatic cancer tissues (n = 29; 26 biopsies, 2 excisions, and 1 fin. needle aspiration). Among the 226 cases, 28 cases (12.4%) had CCNE1 amplification, almost half of which (n = 13, 46.4%) showed liver metastasis. In patients with CCNE1 amplification (n = 28), TP53 mutations (n = 23, 82.1%) and ERBB2 amplification (n = 8, 28.6%) were the most frequent concurrent genetic alterations. In contrast, 42 (21.2%) of 198 patients without CCNE1 amplification showed liver metastasis. CCNE1 amplification was significantly associated with liver metastasis (p = 0.004; odds ratio, 3.219). Our results show that CCNE1 amplification is significantly associated with liver metastasis in a TP53-mutated gastric cancer subtype. Given the frequent association of CCNE1 amplification with liver metastasis, close follow up for liver metastasis and further clinical trials targeting CDK2 inhibitors are warranted.

AKT as a Therapeutic Target for Cancer

Many cellular processes in cancer are attributed to kinase signaling networks. V-akt murine thymoma viral oncogene homolog (AKT) plays a major role in the PI3K/AKT signaling pathways. AKT is activated by PI3K or phosphoinositide-dependent kinases (PDK) as well as growth factors, inflammation, and DNA damage. Signal transduction occurs through downstream effectors such as mTOR, glycogen synthase kinase 3 beta (GSK3β), or forkhead box protein O1 (FOXO1). The abnormal overexpression or activation of AKT has been observed in many cancers, including ovarian, lung, and pancreatic cancers, and is associated with increased cancer cell proliferation and survival. Therefore, targeting AKT could provide an important approach for cancer prevention and therapy. In this review, we discuss the rationale for targeting AKT and also provide details regarding synthetic and natural AKT-targeting compounds and their associated studies.

Mutations Defining Patient Cohorts With Elevated PD-L1 Expression in Gastric Cancer

The immunotherapy agent pembrolizumab has been approved for gastric cancer (GC) patients with recurrent or advanced disease who are PD-L1 positive. Mutations in the primary lesion may drive the expression of immune targets thereby priming the tumor to therapeutic sensitivity. In this study, we aimed to uncover mutations associated with elevated PD-L1 expression in GC patients. Data from 410 GC patients were available, including the mutational spectrum of 39,916 genes and expression values of 20,500 genes. PD-L1 gene expression was compared to the mutational status of each gene separately by using a Mann-Whitney U-test and a Receiver Operating Characteristic test. Only mutations with a prevalence over 5% were considered. Significance was accepted in cases of p < 1E-05 and a fold change over 1.44. Mutations in 209 genes were associated with increased PD-L1 expression. These mutations were enriched in genes related to microtubule-based movement (p = 3.4E-4), cell adhesion (p = 4.9E-4), response to DNA-damage (p = 6.9E-4), and double-strand break-repair (p = 1.6E-3). Mutations in TTK (p = 8.8E-10, AUC = 0.77), COL7A1 (p = 2.0E-9, AUC = 0.74), KIF15 (p = 2.5E-9, AUC = 0.75), and BDP1 (p = 3.3E-9, AUC = 0.74) had the strongest link to elevated PD-L1 expression. Finally, we established a decision tree based on mutations in PIK3CA, MEF2C, SLC11A1, and KIF15 capable to separate patient sub-cohorts with elevated PD-L1 expression. In summary, we identified mutations associated with elevated PD-L1 expression that facilitate the development of better prognostic biomarkers for GC, and might offer insight into the underlying tumor biology.

Stathmin gene silencing suppresses proliferation, migration and invasion of gastric cancer cells via AKT/sCLU and STAT3 signaling

Globally, gastric cancer is the fifth most common malignancy, with high rates of incidence and mortality. The high mortality rate and poor prognosis of gastric cancer are closely associated with its profound invasiveness, high incidence of metastasis, rapid proliferation, and high rate of recurrence. Previous studies have confirmed that stathmin (STMN) has an important role in the occurrence, development and prognosis of gastric cancer. However, the detailed mechanisms by which STMN affects these processes remain unclear. The aim of the present study was to determine how STMN promotes invasion, migration and proliferation in gastric cancer tumor cells. The results of immunohistochemistry indicated that STMN is overexpressed in stomach neoplasm tissues, and that it is associated with migration, invasion, proliferation and anti‑apoptotic states of gastric cancer cells. The secretory proteins of gastric cancer cells with or without STMN knockdown were further analyzed using the isobaric tags for relative and absolute quantitation method to identify differentially expressed proteins verified by reverse transcription‑quantitative polymerase chain reaction and western blot analysis. Inhibition of STMN decreases the levels of clusterin, cystatin C and matrix metalloproteinases, followed by inhibiting the protein kinase B and signal transducer and activation of transcription activation. These findings suggest that STMN could be a promising therapeutic target for gastric cancer.

Association between PIK3CA alteration and prognosis of gastric cancer patients: a meta-analysis

BACKGROUND

Increasing evidence suggests that dysregulation of phosphatidylinositol-4, 5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) plays an important role in carcinogenesis. However, the relationship between PIK3CA expression and gastric cancer (GC) prognosis remains controversial.

METHODS

We searchedPubMed, Embase, Web of Science, and the Cochrane Library databases for relevant studies up to June 30, 2017. Primary outcomes were hazard ratio (HR), odds ratio (OR), and 95% confidence intervals (CI) for association with overall survival and clinicopathological features.

RESULTS

Eleven studies comprising 2481 GC patients were analyzed. Pooled analysis showed that PIK3CA upregulation was significantly associated with worse overall survival (HR = 1.79, 95% CI 1.42-2.27, p< 0.001) at the protein (HR = 1.94, 95% CI 1.52-2.47, p< 0.001) but not the gene (HR = 1.57, 95% CI 0.92-2.69, p= 0.097) level. PIK3CA gene mutation did not correlate with overall survival (HR = 1.05, 95% CI 0.83-1.34, p= 0.666) but was significantly associated with poor tumor differentiation (OR = 0.37, 95% CI 0.17-0.76, p= 0.011).

CONCLUSION

High PIK3CA protein expression predicted poor prognosis in GC, whereas PIK3CA gene amplification or mutation did not. Moreover, PIK3CA mutation was an indicator of poorly differentiated tumors.