Collagens at a glance

Application of spatial omics in gastric cancer

Gastric cancer (GC), a globally prevalent and lethal malignancy, continues to be a key research focus. However, due to its considerable heterogeneity and complex pathogenesis, the treatment and diagnosis of gastric cancer still face significant challenges. With the rapid development of spatial omics technology, which provides insights into the spatial information within tumor tissues, it has emerged as a significant tool in gastric cancer research. This technology affords new insights into the pathology and molecular biology of gastric cancer for scientists. This review discusses recent advances in spatial omics technology for gastric cancer research, highlighting its applications in the tumor microenvironment (TME), tumor heterogeneity, tumor genesis and development mechanisms, and the identification of potential biomarkers and therapeutic targets. Moreover, this article highlights spatial omics' potential in precision medicine and summarizes existing challenges and future directions. It anticipates spatial omics' continuing impact on gastric cancer research, aiming to improve diagnostic and therapeutic approaches for patients. With this review, we aim to offer a comprehensive overview to scientists and clinicians in gastric cancer research, motivating further exploration and utilization of spatial omics technology. Our goal is to improve patient outcomes, including survival rates and quality of life.

Identification of hub genes related to metastasis and prognosis of osteosarcoma and establishment of a prognostic model with bioinformatic methods

Osteosarcoma (OS) is the most common primary malignant bone tumor occurring in children and adolescents. Improvements in our understanding of the OS pathogenesis and metastatic mechanism on the molecular level might lead to notable advances in the treatment and prognosis of OS. Biomarkers related to OS metastasis and prognosis were analyzed and identified, and a prognostic model was established through the integration of bioinformatics tools and datasets in multiple databases. 2 OS datasets were downloaded from the Gene Expression Omnibus database for data consolidation, standardization, batch effect correction, and identification of differentially expressed genes (DEGs); following that, gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed on the DEGs; the STRING database was subsequently used for protein-protein interaction (PPI) network construction and identification of hub genes; hub gene expression was validated, and survival analysis was conducted through the employment of the TARGET database; finally, a prognostic model was established and evaluated subsequent to the screening of survival-related genes. A total of 701 DEGs were identified; by gene ontology and KEGG pathway enrichment analyses, the overlapping DEGs were enriched for 249 biological process terms, 13 cellular component terms, 35 molecular function terms, and 4 KEGG pathways; 13 hub genes were selected from the PPI network; 6 survival-related genes were identified by the survival analysis; the prognostic model suggested that 4 genes were strongly associated with the prognosis of OS. DEGs related to OS metastasis and survival were identified through bioinformatics analysis, and hub genes were further selected to establish an ideal prognostic model for OS patients. On this basis, 4 protective genes including TPM1, TPM2, TPM3, and TPM4 were yielded by the prognostic model.

Impact of tumour stroma-immune interactions on survival prognosis and response to neoadjuvant chemotherapy in bladder cancer

BACKGROUND

The tumour stroma is associated with unfavourable prognosis in diverse solid tumours, but its prognostic and predictive value in bladder cancer (BCa) is unclear.

METHODS

In this multicentre, retrospective study, we included 830 patients with BCa from six independent cohorts. Differences in overall survival (OS) and cancer-specific survival (CSS) were investigated between high-tumour stroma ratio (TSR) and low-TSR groups. Multi-omics analyses, including RNA sequencing, immunohistochemistry, and single-cell RNA sequencing, were performed to study stroma-immune interactions. TSR prediction models were developed based on pelvic CT scans, and the best performing model was selected based on receiver operator characteristic analysis.

FINDINGS

Compared to low-TSR tumours, high-TSR tumours were significantly associated with worse OS (HR = 1.193, 95% CI: 1.046-1.361, P = 0.008) and CSS (HR = 1.337, 95% CI: 1.139-1.569, P < 0.001), and lower rate of pathological complete response (pCR) to neoadjuvant chemotherapy (NAC). High-TSR tumours exhibited higher infiltration of immunosuppressive cells, including Tregs and tumour-associated neutrophils, while low-TSR tumours exhibited higher infiltration of immune-activating cells such as CD8+ Teff and XCR1+ dendritic cells. The TSR prediction model was developed by combining the intra-tumour and tumour base radiomics features, and showed good performance to predict high-TSR, as indicted by area under the curve of 0.871 (95% CI: 0.821-0.921), 0.821 (95% CI: 0.731-0.911), and 0.801 (95% CI: 0.737-0.865) in the training, internal validation, and external validation cohorts, respectively. In patients with low predicted TSR, 92.3% (12/13) achieved pCR, while only 35.3% (6/17) of patients with high predicted TSR achieved pCR.

INTERPRETATION

The tumour stroma was found to be significantly associated with clinical outcomes in patients with BCa as a result of tumour stroma-immune interactions. The radiomics prediction model provided non-invasive evaluation of TSR and was able to predict pCR in patients receiving NAC for BCa.

FUNDING

This work was supported by National Natural Science Foundation of China (Grant No. 82373254 and 81961128027), Guangdong Provincial Natural Science Foundation (Grant No. 2023A1515010258), Science and Technology Planning Project of Guangdong Province (Grant No. 2023B1212060013). Science and Technology Program of Guangzhou (SL2022A04J01754), Sun Yat-Sen Memorial Hospital Clinical Research 5010 Program (Grant No. SYS-5010Z-202401).

Unlocking the Crucial Role of Cancer-Associated Fibroblasts in Tumor Metastasis: Mechanisms and Therapeutic Prospects

BACKGROUND

Tumor metastasis represents a stepwise progression and stands as a principal determinant of unfavorable prognoses among cancer patients. Consequently, an in-depth exploration of its mechanisms holds paramount clinical significance. Cancer-associated fibroblasts (CAFs), constituting the most abundant stromal cell population within the tumor microenvironment (TME), have garnered robust evidence support for their pivotal regulatory roles in tumor metastasis.

AIM

of Review This review systematically explores the roles of CAFs at eight critical stages of tumorigenic dissemination: 1) extracellular matrix (ECM) remodeling, 2) epithelial-mesenchymal transition (EMT), 3) angiogenesis, 4) tumor metabolism, 5) perivascular migration, 6) immune escape, 7) dormancy, and 8) premetastatic niche (PMN) formation. Additionally, we provide a compendium of extant strategies aimed at targeting CAFs in cancer therapy. Key Scientific Concepts of Review This review delineates a structured framework for the interplay between CAFs and tumor metastasis while furnishing insights for the potential therapeutic developments. It contributes to a deeper understanding of cancer metastasis within the TME, facilitating the utilization of CAF-targeting therapies in anti-metastatic approaches.

Cancer-associated fibroblasts: protagonists of the tumor microenvironment in gastric cancer

Enhanced knowledge of the interaction of cancer cells with their environment elucidated the critical role of tumor microenvironment in tumor progression and chemoresistance. Cancer-associated fibroblasts act as the protagonists of the tumor microenvironment, fostering the metastasis, stemness, and chemoresistance of cancer cells and attenuating the anti-cancer immune responses. Gastric cancer is one of the most aggressive cancers in the clinic, refractory to anti-cancer therapies. Growing evidence indicates that cancer-associated fibroblasts are the most prominent risk factors for a poor tumor immune microenvironment and dismal prognosis in gastric cancer. Therefore, targeting cancer-associated fibroblasts may be central to surpassing resistance to conventional chemotherapeutics, molecular-targeted agents, and immunotherapies, improving survival in gastric cancer. However, the heterogeneity in cancer-associated fibroblasts may complicate the development of cancer-associated fibroblast targeting approaches. Although single-cell sequencing studies started dissecting the heterogeneity of cancer-associated fibroblasts, the research community should still answer these questions: "What makes a cancer-associated fibroblast protumorigenic?"; "How do the intracellular signaling and the secretome of different cancer-associated fibroblast subpopulations differ from each other?"; and "Which cancer-associated fibroblast subtypes predominate specific cancer types?". Unveiling these questions can pave the way for discovering efficient cancer-associated fibroblast targeting strategies. Here, we review current knowledge and perspectives on these questions, focusing on how CAFs induce aggressiveness and therapy resistance in gastric cancer. We also review potential therapeutic approaches to prevent the development and activation of cancer-associated fibroblasts via inhibition of CAF inducers and CAF markers in cancer.

Microdissection of cancer-associated fibroblast infiltration subtypes unveils the secreted SERPINE2 contributing to immunosuppressive microenvironment and immuotherapeutic resistance in gastric cancer: A large-scale study integrating bulk and single-cell transcriptome profiling

In the era of immunotherapy, the suboptimal response rate and the development of acquired resistance among the initial beneficiaries continue to present significant challenges across multiple malignancies, including gastric cancer (GC). Considering that the interactions of tumor stroma, especially the cancer-associated fibroblasts (CAFs), with immune and tumor cells, play indispensable roles in tumor progression, tumor microenvironment remodeling and therapeutic responsiveness, in-depth exploration on the roles of CAFs and pivotal mediators of their functions may provide novel clues to increase the effectiveness of current immunotherapeutic drugs and further achieve synergistic antitumor response. Herein, through the consensus clustering of canonical biomarkers, three GC subclasses with different abundance of CAFs were virtually microdissected in four integrated bulk cohorts encompassing 2148 GC patients from 11 independent datasets. An extensive immunogenomic analysis revealed that tumors with high CAFs infiltration were characterized with unfavorable outcomes, aggressive phenotypes, decreased tumor immunogenicity, high risk of immune evasion and thus immunotherapeutic resistance. By leveraging large-scale single-cell transcriptomic profiling, a series of CAF-secreted proteins were identified, among which the SERPINE2 was confirmed to be restrictively enriched in stromal fibroblasts of GC tissues and contribute to promoting a protumor milieu and fostering an immunosuppressive microenvironment via bioinformatics computations and tissue microarray analysis. Moreover, pan-cancer investigations generalized the immunological roles of SERPINE2, especially in pan-gastrointestinal malignancies, with multiple real-world immunotherapy cohorts further confirming its implications on predicting immunotherapeutic efficacy. In conclusion, these findings suggest that the CAF-derived SERPINE2 is a promising immune-oncology target with therapeutic implications to further synergize the immunotherapeutic combinations.

Crosstalk between Cancer Cells and Cancer-Associated Fibroblasts Mediated by TGF-β1-IGFBP7 Signaling Promotes the Progression of Infiltrative Gastric Cancer

Patients with infiltrative-type gastric cancer (GC) (Ming's classification) have a poor prognosis due to more metastasis and recurrence. Cancer-associated fibroblasts (CAFs) in infiltrative-type extracellular matrix (ECM) have specific characteristics compared with those of expansive types with respect to metastasis, but the mechanism is still unclear. Based on our proteomics data, TCGA data analysis, and immunohistochemical staining results, significantly higher expression of IGFBP7 was observed in GC, especially in the infiltrative type, and was associated with a poor prognosis. Combining single-cell transcriptome data from GEO and multiple immunofluorescence staining on tissue showed that the differential expression of IGFBP7 mainly originated from myofibroblastic CAFs, the subgroup with higher expression of PDGFRB and α-SMA. After treating primary normal fibroblasts (NFs) with conditional medium or recombined protein, it was demonstrated that XGC-1-derived TGF-β1 upregulated the expression of IGFBP7 in the cells and its secretion via the P-Smad2/3 pathway and mediated its activation with higher FAP, PDGFRB, and α-SMA expression. Then, either conditional medium from CAFs with IGFBP7 overexpression or recombined IGFBP7 protein promoted the migration, invasion, colony formation, and sphere growth ability of XGC-1 and MGC-803, respectively. Moreover, IGFBP7 induced EMT in XGC-1. Therefore, our study clarified that in the tumor microenvironment, tumor-cell-derived TGF-β1 induces the appearance of the IGFBP7+ CAF subgroup, and its higher IGFBP7 extracellular secretion level accelerates the progression of tumors.

Fibroblast Activation Protein Inhibitor PET/CT in Gastric Cancer

Like other major cancers, gastric cancer expresses fibroblast activation protein (FAP) in cancer-associated fibroblasts. Many recent studies have reported the utility and superiority of FAP inhibitor (FAPI)-PET over [18F]fluorodeoxyglucose (FDG)-PET in gastric cancers, from initial staging to recurrence detection. FAPI-PET shows higher accumulation in primary sites and metastatic lesions than does FDG-PET, especially for the detection of peritoneal carcinomatosis. In the case of gastric signet ring cell carcinoma, FAPI-PET showed excellent performance, as uptake is usually weak on FDG-PET in this cohort.

Integrated single-cell and bulk RNA sequencing analysis identifies a cancer-associated fibroblast-related gene signature for predicting survival and therapy in gastric cancer

As the dominant component of the tumor microenvironment, cancer-associated fibroblasts (CAFs), play a vital role in tumor progression. An increasing number of studies have confirmed that CAFs are involved in almost every aspect of tumors including tumorigenesis, metabolism, invasion, metastasis and drug resistance, and CAFs provide an attractive therapeutic target. This study aimed to explore the feature genes of CAFs for potential therapeutic targets and reliable prediction of prognosis in patients with gastric cancer (GC). Bioinformatic analysis was utilized to identify the feature genes of CAFs in GC by performing an integrated analysis of single-cell and transcriptome RNA sequencing using R software. Based on these feature genes, a CAF-related gene signature was constructed for prognostic prediction by LASSO. Simultaneously, survival analysis and nomogram were performed to validate the prognostic predictive value of this gene signature, and qRT-PCR and immunohistochemical staining verified the expression of the feature genes of CAFs. In addition, small molecular drugs for gene therapy of CAF-related gene signatures in GC patients were identified using the connectivity map (CMAP) database. A combination of nine CAF-related genes was constructed to characterize the prognosis of GC, and the prognostic potential and differential expression of the gene signature were initially validated. Additionally, three small molecular drugs were deduced to have anticancer properties on GC progression. By integrating single-cell and bulk RNA sequencing analyses, a novel gene signature of CAFs was constructed. The results provide a positive impact on future research and clinical studies involving CAFs for GC.

Cancer-associated fibroblasts, and clinicopathological characteristics and prognosis of gastric cancer: A systematic review and meta-analysis

Objective

To systematically evaluate the relationship between cancer-associated fibroblasts (CAFs) and clinicopathological characteristics and prognosis of gastric cancer, so as to provide new directions and clinical evidence for the diagnosis and treatment of this disease.

Methods

We searched PubMed, Embase, Web of Science, and The Cochrane Library to identify studies on the correlation between tumor-associated fibroblasts and the diagnosis and prognosis of gastric cancer. Two researchers screened the literature independently to extract data, evaluated the quality of the included studies, and used the Review Manager 5.4 software to perform a meta-analysis.

Results

A total of 14 studies involving a total of 2,703 patients were included. The meta-analysis results showed that high expression of CAFs was associated with stage III-IV gastric cancer (relative risk ratio [RR]=1.59; 95% confidence interval [CI]: [1.24-2.04]; P=0.0003), lymph node metastasis (RR=1.51; 95% CI: [1.23-1.87]; P=0.0001), serosal infiltration (RR=1.56, 95% CI: [1.24-1.95]; P=0.0001), diffuse and mixed types in Lauren classification (RR=1.43; 95% CI: [1.18-1.74]; P=0.0003), vascular invasion (RR=1.99; 95% CI: [1.26-3.14]; P=0.003), and overall survival (hazard ratio [HR]=1.38; 95% CI: [1.22-1.56]; P<0.00001). However, the high expression of CAFs was not significantly correlated with poorly differentiated gastric cancer (RR=1.03; 95% CI: [0.96-1.10]; P=0.45) and gastric cancer with tumor diameter >5 cm (RR=1.34; 95% CI: [0.98-1.83]; P=0.07).

Conclusion

The findings of this meta-analysis demonstrated that high expression of CAFs is closely associated with the traditional pathological indicators related to poor prognosis in gastric cancer, and is a valuable prognostic factor in this setting.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022358165.

Cancer-associated fibroblasts: Origin, function, imaging, and therapeutic targeting

The tumor microenvironment (TME) is emerging as one of the primary barriers in cancer therapy. Cancer-associated fibroblasts (CAF) are a common inhabitant of the TME in several tumor types and play a critical role in tumor progression and drug resistance via different mechanisms such as desmoplasia, angiogenesis, immune modulation, and cancer metabolism. Due to their abundance and significance in pro-tumorigenic mechanisms, CAF are gaining attention as a diagnostic target as well as to improve the efficacy of cancer therapy by their modulation. In this review, we highlight existing imaging techniques that are used for the visualization of CAF and CAF-induced fibrosis and provide an overview of compounds that are known to modulate CAF activity. Subsequently, we also discuss CAF-targeted and CAF-modulating nanocarriers. Finally, our review addresses ongoing challenges and provides a glimpse into the prospects that can spearhead the transition of CAF-targeted therapies from opportunity to reality.

Highlight selection of radiochemistry and radiopharmacy developments by editorial board

Background

The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biyearly highlight commentary to update the readership on trends in the field of radiopharmaceutical development.

Results

This commentary of highlights has resulted in 23 different topics selected by each member of the Editorial Board addressing a variety of aspects ranging from novel radiochemistry to first in man application of novel radiopharmaceuticals and also a contribution in relation to MRI-agents is included.

Conclusion

Trends in (radio)chemistry and radiopharmacy are highlighted demonstrating the progress in the research field being the scope of EJNMMI Radiopharmacy and Chemistry.

Single-Cell Atlas of Lineage States, Tumor Microenvironment, and Subtype-Specific Expression Programs in Gastric Cancer

Gastric cancer heterogeneity represents a barrier to disease management. We generated a comprehensive single-cell atlas of gastric cancer (>200,000 cells) comprising 48 samples from 31 patients across clinical stages and histologic subtypes. We identified 34 distinct cell-lineage states including novel rare cell populations. Many lineage states exhibited distinct cancer-associated expression profiles, individually contributing to a combined tumor-wide molecular collage. We observed increased plasma cell proportions in diffuse-type tumors associated with epithelial-resident KLF2 and stage-wise accrual of cancer-associated fibroblast subpopulations marked by high INHBA and FAP coexpression. Single-cell comparisons between patient-derived organoids (PDO) and primary tumors highlighted inter- and intralineage similarities and differences, demarcating molecular boundaries of PDOs as experimental models. We complemented these findings by spatial transcriptomics, orthogonal validation in independent bulk RNA-sequencing cohorts, and functional demonstration using in vitro and in vivo models. Our results provide a high-resolution molecular resource of intra- and interpatient lineage states across distinct gastric cancer subtypes.

SIGNIFICANCE

We profiled gastric malignancies at single-cell resolution and identified increased plasma cell proportions as a novel feature of diffuse-type tumors. We also uncovered distinct cancer-associated fibroblast subtypes with INHBA-FAP-high cell populations as predictors of poor clinical prognosis. Our findings highlight potential origins of deregulated cell states in the gastric tumor ecosystem. This article is highlighted in the In This Issue feature, p. 587.

PET/CT Imaging of Activated Cancer-Associated Fibroblasts Predict Response to PD-1 Blockade in Gastric Cancer Patients

Background

Promising development in immune checkpoint blockade (ICB) therapy has shown remarkable results in the treatment of gastric cancer (GC). However, the objective response rate in GC remains unsatisfactory. Noninvasive imaging to predict responses to ICB therapy via tumor microenvironment (TME) assessment is needed. Accordingly, this study aimed to evaluate the role of ⁶⁸Ga-FAPI-04 PET/CT in the assessment of the immunosuppressive TME in GC and to cross-correlate imaging findings with responses to ICB therapy.

Methods

The correlation between fibroblast-activation-protein (FAP) expression and immunosuppressive cell infiltration was analyzed using The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO) database, and GC tissue microarrays. To characterize the TME, TMEscores were calculated based on RNA-seq data from four GC patients. A total of 21 patients with GC underwent ⁶⁸Ga-FAPI-04 PET/CT before ICB treatment, and two of them were imaged after ICB therapy.

Results

FAP expression was found to be closely correlated with poor prognosis and infiltration of immunosuppressive cells, including myeloid-derived suppressor cells (MDSCs), exhausted T cells, and regulatory T cells (Tregs) in GC. We also found a strong relationship (R² = 0.9678, p = 0.0162) between ⁶⁸Ga-FAPI-04 uptake and TMEscore. Further analyses indicated that high ⁶⁸Ga-FAPI-04 uptake was correlated with reduced therapeutic benefits from ICB therapy.

Conclusions

⁶⁸Ga-FAPI-04 PET/CT may be used to noninvasively image the cancer-associated fibroblasts immunosuppressive TME in vivo and also potentially serve as a predictive biomarker of survival and antitumor immune response among patients who received ICB therapies.

Comparison of [68 Ga]Ga-FAPI-04 and [18F]-FDG for the detection of primary and metastatic lesions in patients with gastric cancer: a bicentric retrospective study

INTRODUCTION

The low sensitivity of [¹⁸F]-fluorodeoxyglucose ([¹⁸F]-FDG) for the diagnosis of gastric cancer limits its application. In this study, we aimed to investigate the potential advantage of [⁶⁸ Ga]Ga-FAPI-04 over [¹⁸F]-FDG in the evaluation of gastric cancer.

METHODS

This was a bicentric retrospective analysis of a prospective parent study (clinical trial: HS-KY-2020-826 (Huashan Hospital) and DF-2020-102 (Shanghai East Hospital)). Thirty-eight patients with gastric cancer (31 with adenocarcinoma and 7 with signet ring cell carcinoma) were included in this study. All of the participants underwent [⁶⁸ Ga]Ga-FAPI-04 and [¹⁸F]-FDG imaging by positron emission tomography (PET)/computed tomography (CT) or PET/magnetic resonance (MR). The scans were interpreted by two experienced nuclear medicine physicians, and the maximum standardized uptake value (SUV_max) was calculated. Histopathological findings obtained from biopsy or resected surgical specimens were used as a reference for the final diagnosis.

RESULTS

For the detection of primary gastric cancer, the sensitivities of [⁶⁸ Ga]Ga-FAPI-04 PET and [¹⁸F]-FDG PET were 100% (38/38) and 82% (31/38), respectively (P = 0.016). Four cases of adenocarcinoma and three cases of signet ring cell carcinoma were missed by [¹⁸F]-FDG PET. The mean SUV_max of [⁶⁸ Ga]Ga-FAPI-04 in tumours greater than 4 cm (11.0 ± 4.5) was higher than that in tumours less than 4 cm (4.5 ± 3.2) (P = 0.0015). The mean SUV_max of [⁶⁸ Ga]Ga-FAPI-04 was higher in T2-4 tumours (9.7 ± 4.4) than in T1 tumours (3.1 ± 1.5) (P = 0.0002). For the detection of metastatic lesions, the sensitivities of [⁶⁸ Ga]Ga-FAPI-04 PET and [¹⁸F]-FDG PET in 10 patients with regional lymph node metastasis and distant metastasis were 6/10 and 5/10, respectively.

CONCLUSION

In this selected cohort, [⁶⁸ Ga]Ga-FAPI-04 PET had a superior detection rate than [¹⁸F]-FDG PET for primary gastric cancer. [⁶⁸ Ga]Ga-FAPI-04 PET could provide better performance with regard to gastric cancer diagnosis and staging. Prospective clinical trials are warranted.

The functional cross talk between cancer cells and cancer associated fibroblasts from a cancer mechanics perspective

The function of biological tissues in health and disease is regulated at cellular level and is highly influenced by the physical microenvironment, through the interaction of forces between cells and ECM, which are perceived through mechanosensing pathways. In cancer, both chemical and physical signaling cascades and their interactions are involved during cell-cell and cell-ECM communications to meet requirements of tumor growth. Among stroma cells, cancer associated fibroblasts (CAFs) play key role in tumor growth and pave the way for cancer cells to initiate metastasis and invasion to other tissues, and without recruitment of CAFs, the process of cancer invasion is dysfunctional. This is through an intense chemical and physical cross talks with tumor cells, and interactive remodeling of ECM. During such interaction CAFs apply traction forces and depending on the mechanical properties, deform ECM and in return receive physical signals from the micromechanical environment. Such interaction leads to ECM remodeling by manipulating ECM structure and its mechanical properties. The results are in form of deposition of extra fibers, stiffening, rearrangement and reorganization of fibrous structure, and degradation which are due to a complex secretion and expression of different markers triggered by mechanosensing of tumor cells, specially CAFs. Such events define cancer progress and invasion of cancer cells. A systemic knowledge of chemical and physical factors provides a holistic view of how cancer process and enhances the current treatment methods to provide more diversity among targets that involves tumor cells and ECM structure.

Radiographical assessment of tumour stroma and treatment outcomes using deep learning: a retrospective, multicohort study

BACKGROUND

The tumour stroma microenvironment plays an important part in disease progression and its composition can influence treatment response and outcomes. Histological evaluation of tumour stroma is limited by access to tissue, spatial heterogeneity, and temporal evolution. We aimed to develop a radiological signature for non-invasive assessment of tumour stroma and treatment outcomes.

METHODS

In this multicentre, retrospective study, we analysed CT images and outcome data of 2209 patients with resected gastric cancer from five independent cohorts recruited from two centres (Nanfang Hospital of Southern Medical University [Guangzhou, China] and Sun Yat-sen University Cancer Center [Guangzhou, China]). Patients with histologically confirmed gastric cancer, at least 15 lymph nodes harvested, preoperative abdominal CT available, and complete clinicopathological and follow-up data were eligible for inclusion. Tumour tissue was collected for patients in the training cohort (321 patients), internal validation cohort one (246 patients), and external validation cohort one (128 patients). Four stroma classes were defined according to the protein expression of α-smooth muscle actin and periostin assessed by immunohistochemistry. The primary objective was to predict the histologically based stroma classes by using preoperative CT images. We trained a deep convolutional neural network model using the training cohort and tested the model in the internal and external validation cohort one. We evaluated the model's association with prognosis in the training cohort, two internal, and two external validation cohorts and compared outcomes of patients who received or did not receive adjuvant chemotherapy.

FINDINGS

The deep-learning model achieved a high diagnostic accuracy for assessing tumour stroma in both internal validation cohort one (area under the receiver operating characteristic curve [AUC] 0·96-0·98]) and external validation cohort one (AUC 0·89-0·94). The stromal imaging signature was significantly associated with disease-free survival and overall survival in all cohorts (p<0·0001). The predicted stroma classes remained an independent prognostic factor adjusting for clinicopathological variables including tumour size, stage, differentiation, and Lauren histology. In patients with stage II or III disease in predicted stroma classes one and two subgroups, patients who received adjuvant chemotherapy had improved survival compared with those who did not (in those with stage II disease hazard ratio [HR] 0·48 [95% CI 0·29-0·77], p=0·0021; and in those with stage III disease HR 0·70 [0·57-0·85], p=0·00042). However, in the other two subgroups adjuvant chemotherapy was not associated with survival and might even be detrimental in the predicted stroma class 4 subgroup (HR 1·48 [1·08-2·03], p=0·013).

INTERPRETATION

The deep-learning model could allow for accurate and non-invasive evaluation of tumour stroma from CT images in gastric cancer. The radiographical model predicted chemotherapy outcomes and could be used in combination with clinicopathological criteria to refine prognosis and inform treatment decisions of patients with gastric cancer.

FUNDING

None.

Cancer-Associated Fibroblasts Promote Aggressive Gastric Cancer Phenotypes via Heat Shock Factor 1-Mediated Secretion of Extracellular Vesicles

Gastric cancer is the third most lethal cancer worldwide, and evaluation of the genomic status of gastric cancer cells has not translated into effective prognostic or therapeutic strategies. We therefore hypothesize that outcomes may depend on the tumor microenvironment (TME), in particular, cancer-associated fibroblasts (CAF). However, very little is known about the role of CAFs in gastric cancer. To address this, we mapped the transcriptional landscape of human gastric cancer stroma by microdissection and RNA sequencing of CAFs from patients with gastric cancer. A stromal gene signature was associated with poor disease outcome, and the transcription factor heat shock factor 1 (HSF1) regulated the signature. HSF1 upregulated inhibin subunit beta A and thrombospondin 2, which were secreted in CAF-derived extracellular vesicles to the TME to promote cancer. Together, our work provides the first transcriptional map of human gastric cancer stroma and highlights HSF1 and its transcriptional targets as potential diagnostic and therapeutic targets in the genomically stable tumor microenvironment. SIGNIFICANCE: This study shows how HSF1 regulates a stromal transcriptional program associated with aggressive gastric cancer and identifies multiple proteins within this program as candidates for therapeutic intervention. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/7/1639/F1.large.jpg.

Accumulation of Nicotinamide N-Methyltransferase (NNMT) in Cancer-associated Fibroblasts: A Potential Prognostic and Predictive Biomarker for Gastric Carcinoma

Nicotinamide N-methyltransferase (NNMT), a major metabolic regulator, has been identified as a predictor of cancer prognosis in ovarian and colorectal cancers. The study aims to evaluate the significance of stromal NNMT in gastric cancer (GC). Expression of stromal NNMT in 612 GC and 92 non-malignant tissues specimens was investigated by immunohistochemistry (IHC). The association between NNMT expression and occurrence of cancer or patient outcome was further analyzed, and the factors contributing to disease prognosis were evaluated by multiple Cox models. Stromal NNMT expression was higher in the malignant tissue (p<0.001). NNMT expression was significantly associated with GC stage (p=0.006). Compared to stromal "NNMT-low" cases, "NNMT-high" cases has lower disease-specific survival (hazard ratio [HR], 2.356; 95% confidence interval [CI] = 1.591-3.488; p<0.001) and disease-free survival (HR = 2.265; 95% CI = 1.529-3.354; p<0.001), as observed by multivariate Cox analysis after adjusting for stromal NNMT expression with other factors such as tumor grade and size. Notably, patients with stage II NNMT-low GC might be negatively affected by adjuvant chemotherapy, but lower stromal NNMT expression predicted a more favorable prognosis for GC. Our study confirmed that stromal NNMT expression is significantly increased in GC, which predicts an unfavorable post-operative prognosis for GC.

Targeting Galectin-1 by Aflibercept Strongly Enhances Its Antitumor Effect in Neuroendocrine Carcinomas

BACKGROUND

Galectin-1 (Gal-1) plays major roles in cancer by modulating different processes leading to tumor development and progression. In the last years, it has been suggested as a promising target for anticancer therapy. Recently, aflibercept has shown high affinity for Gal-1. Here, we investigated how aflibercept could exert its antitumor activity via Gal-1-driven pathways in neuroendocrine carcinomas (NECs).

METHODS AND RESULTS

NEC tumor xenografts were used to assess the effect of aflibercept on Gal-1 functions. Aflibercept induced a significant reduction of Gal-1 at epithelial, stromal, and extracellular localizations in lung NEC, whereas this was not observed in colon NECs, which displayed low expression of Gal-1. Additionally, aflibercept significantly reduced p-VEGFR2 protein, extracellular matrix remodeling, epithelial-mesenchymal transition, and activation of cancer-associated fibroblast hampering cell invasion in lung NEC but not in colon NEC. Gal-1 screening in human NECs confirmed that pulmonary and pancreatic tumors displayed higher levels of Gal-1 than colon NECs, becoming good candidates to benefit from aflibercept treatment.

CONCLUSIONS

The lack of validated predictive markers of aflibercept is a weakness for guaranteeing the best treatment management with this drug. This work provides new mechanistic insight of aflibercept depending on Gal-1. Thus, in tumors overexpressing Gal-1, aflibercept has not only an antiangiogenic effect but also prevents Gal-1-mediated tumor-stroma cross talk. The stronger aflibercept effect in tumors with high levels of Gal-1 points out this protein as a molecular marker to predict the efficacy of this agent not only for NECs but also for other tumors with high levels of this protein.

Targeting the Tumor Microenvironment with Fluorescence-Activatable Bispecific Endoglin/Fibroblast Activation Protein Targeting Liposomes

Liposomes are biocompatible nanocarriers with promising features for targeted delivery of contrast agents and drugs into the tumor microenvironment, for imaging and therapy purposes. Liposome-based simultaneous targeting of tumor associated fibroblast and the vasculature is promising, but the heterogeneity of tumors entails a thorough validation of suitable markers for targeted delivery. Thus, we elucidated the potential of bispecific liposomes targeting the fibroblast activation protein (FAP) on tumor stromal fibroblasts, together with endoglin which is overexpressed on tumor neovascular cells and some neoplastic cells. Fluorescence-quenched liposomes were prepared by hydrating a lipid film with a high concentration of the self-quenching near-infrared fluorescent dye, DY-676-COOH, to enable fluorescence detection exclusively upon liposomal degradation and subsequent activation. A non-quenched green fluorescent phospholipid was embedded in the liposomal surface to fluorescence-track intact liposomes. FAP- and murine endoglin-specific single chain antibody fragments were coupled to the liposomal surface, and the liposomal potentials validated in tumor cells and mice models. The bispecific liposomes revealed strong fluorescence quenching, activatability, and selectivity for target cells and delivered the encapsulated dye selectively into tumor vessels and tumor associated fibroblasts in xenografted mice models and enabled their fluorescence imaging. Furthermore, detection of swollen lymph nodes during intra-operative simulations was possible. Thus, the bispecific liposomes have potentials for targeted delivery into the tumor microenvironment and for image-guided surgery.

Immunological Aspects of the Tumor Microenvironment and Epithelial-Mesenchymal Transition in Gastric Carcinogenesis

Infection with Helicobacter pylori, a Gram-negative, microaerophilic pathogen often results in gastric cancer in a subset of affected individuals. This explains why H. pylori is the only bacterium classified as a class I carcinogen by the World Health Organization. Several studies have pinpointed mechanisms by which H. pylori alters signaling pathways in the host cell to cause diseases. In this article, the authors have reviewed 234 studies conducted over a span of 18 years (2002-2020). The studies investigated the various mechanisms associated with gastric cancer induction. For the past 1.5 years, researchers have discovered new mechanisms contributing to gastric cancer linked to H. pylori etiology. Alongside alteration of the host signaling pathways using oncogenic CagA pathways, H. pylori induce DNA damage in the host and alter the methylation of DNA as a means of perturbing downstream signaling. Also, with H. pylori, several pathways in the host cell are activated, resulting in epithelial-to-mesenchymal transition (EMT), together with the induction of cell proliferation and survival. Studies have shown that H. pylori enhances gastric carcinogenesis via a multifactorial approach. What is intriguing is that most of the targeted mechanisms and pathways appear common with various forms of cancer.

CD66b+ neutrophils and α-SMA+ fibroblasts predict clinical outcomes and benefits from postoperative chemotherapy in gastric adenocarcinoma

Background

Emerging evidence indicates that the tumor microenvironment (TME) influences tumor progression through the various cells it contains. Tumor‐associated neutrophils (TANs) and cancer‐associated fibroblasts (CAFs) are prominent constituents of diverse malignant solid tumors and are crucial in the TME and cancer evolution. However, the relationships and combined prognostic value of these two cell types are not known in gastric adenocarcinoma (GAC).

Materials and Methods

In total, 215 GAC patients who underwent curative surgery were enrolled. TANs were assessed by immunohistochemical staining for CD66b, and CAFs were evaluated by immunohistochemical staining for α‐smooth muscle actin (α‐SMA).

Results

The percentages of patients with high‐density TANs and CAFs in GAC tissue were 47.9% (103/215) and 43.3% (93/215), respectively. The densities of TANs and CAFs in GAC tissue samples were markedly elevated and independently correlated with GAC clinical outcomes. A strong correlation (R = .348, P < .001) was detected between TANs and CAFs in GAC. The combination of TANs and CAFs produced a more exact outcome than either factor alone. Patients with an α‐SMA^lowCD66b^high (hazard ratio [HR] = 1.791; 95% CI: 1.062‐3.021; P = .029), α‐SMA^highCD66b^low (HR = 2.402; 95% CI: 1.379‐4.183; P = .002), or α‐SMA^highCD66b^high (HR = 3.599; 95% CI: 2.330‐5.560; P < .001) phenotype were gradually correlated with poorer disease‐free survival than the subset of patients with an α‐SMA^lowCD66b^low phenotype. The same results were observed for disease‐specific survival in the subgroups. Noticeably, in stage II‐III patients with the α‐SMA^lowCD66b^low phenotype, an advantage was obtained with postoperative chemotherapeutics, and the risk of a poor prognosis was reduced compared with stage II‐III patients with the α‐SMA^lowCD66b^high, α‐SMA^highCD66b^low or α‐SMA^highCD66b^high phenotype (HR: 0.260, 95% CI: 0.124‐0.542, P < .001 for disease‐free survival; and HR: 0.258, 95% CI: 124‐0.538, P < .001 for disease‐specific survival).

Conclusion

Overall, we concluded that the combination of CD66b⁺ TANs and α‐SMA⁺ CAFs could be used as an independent factor for patient outcomes and to identify GAC patients who might benefit from the administration of postoperative chemotherapeutics.

The Gastrointestinal Tumor Microenvironment: An Updated Biological and Clinical Perspective

Gastrointestinal cancers are still responsible for high numbers of cancer-related deaths despite advances in therapy. Tumor-associated cells play a key role in tumor biology, by supporting or halting tumor development through the production of extracellular matrix, growth factors, cytokines, and extracellular vesicles. Here, we review the roles of these tumor-associated cells in the initiation, angiogenesis, immune modulation, and resistance to therapy of gastrointestinal cancers. We also discuss novel diagnostic and therapeutic strategies directed at tumor-associated cells and their potential benefits for the survival of these patients.

Exosomal miRNA-139 in cancer-associated fibroblasts inhibits gastric cancer progression by repressing MMP11 expression

Solid tumors consist of various types of stromal cells in addition to cancer cells. Cancer-associated fibroblasts (CAFs) are a major component of the tumor stroma and play an essential role in tumor progression and metastasis in a variety of malignancies, including gastric cancer. However, the effects of CAFs on gastric cancer cells' progression and metastasis are not well studied. Here we show that matrix metalloproteinase 11 (MMP11) in exosomes secreted from CAFs can be delivered into gastric cancer cells. Gastric CAFs promote gastric cancer cell migration partially through exosomal MMP11. Moreover, MMP11 is overexpressed in exosomes purified from plasma of gastric cancer patients and tumor tissues and associated with overall survival of gastric patients. We also find that MMP11 is negatively regulated by exosomal miR-139 in the CAFs of gastric cancer. Exosomal miR-139 inhibits tumor growth and metastasis of gastric cancer cells by decreasing the expression of MMP11 in vitro and in vivo. Thus, we propose that exosomal miR-139 derived from gastric CAFs could inhibit the progression and metastasis of gastric cancer by decreasing MMP11 in tumor microenvironment.

Relationship between the expressions of PD-L1 and tumour-associated fibroblasts in gastric cancer

Previous studies have focused on the changes of tumour cells in immune escape, and less is known about the effect of tumour microenvironment (TME) on immune escape. Tumour-associated fibroblasts (TAF) is an important part of the TME and has special physiological and biochemical characteristics, but the specific mechanism has not been clarified. In order to investigate the effect of TAF on the expression of PD-L1 in gastric cancer cells, gastric cancer cell lines MNK45, SGC7901 were non-contact co-culturing with TAF 1, 3 and 7 d via transwell. PD-L1 mRNA and protein expression were detected using qRT-PCR and FCM. Then, 95 cases of gastric cancer tissues were selected and evaluated PD-L1 and TAF expressions by immunohistochemical examination. The results showed that the mRNA and protein expression of PD-L1 in the experiment group were significantly higher than that in the control group. PD-L1 expression was associated with massive lymphocyte infiltration, diffuse/mixed histology and intratumoral TAFs in gastric cancers. In conclusion, TAFs promoted the growth in gastric cancer cell lines by increased the PD-L1 expression.

AHR and GPER mediate the stimulatory effects induced by 3-methylcholanthrene in breast cancer cells and cancer-associated fibroblasts (CAFs)

BACKGROUND

The chemical carcinogen 3-methylcholanthrene (3MC) binds to the aryl hydrocarbon receptor (AHR) that regulates the expression of cytochrome P450 (CYP) enzymes as CYP1B1, which is involved in the oncogenic activation of environmental pollutants as well as in the estrogen biosynthesis and metabolism. 3MC was shown to induce estrogenic responses binding to the estrogen receptor (ER) α and stimulating a functional interaction between AHR and ERα. Recently, the G protein estrogen receptor (GPER) has been reported to mediate certain biological responses induced by endogenous estrogens and environmental compounds eliciting an estrogen-like activity.

METHODS

Molecular dynamics and docking simulations were performed to evaluate the potential of 3MC to interact with GPER. SkBr3 breast cancer cells and cancer-associated fibroblasts (CAFs) derived from breast tumor patients were used as model system. Real-time PCR and western blotting analysis were performed in order to evaluate the activation of transduction mediators as well as the mRNA and protein levels of CYP1B1 and cyclin D1. Co-immunoprecipitation studies were performed in order to explore the potential of 3MC to trigger the association of GPER with AHR and EGFR. Luciferase assays were carried out to determine the activity of CYP1B1 promoter deletion constructs upon 3MC exposure, while the nuclear shuttle of AHR induced by 3MC was assessed through confocal microscopy. Cell proliferation stimulated by 3MC was determined as biological counterpart of the aforementioned experimental assays. The statistical analysis was performed by ANOVA.

RESULTS

We first ascertained by docking simulations the ability of 3MC to interact with GPER. Thereafter, we established that 3MC activates the EGFR/ERK/c-Fos transduction signaling through both AHR and GPER in SkBr3 cells and CAFs. Then, we found that these receptors are involved in the up-regulation of CYP1B1 and cyclin D1 as well as in the stimulation of growth responses induced by 3MC.

CONCLUSIONS

In the present study we have provided novel insights regarding the molecular mechanisms by which 3MC may trigger a physical and functional interaction between AHR and GPER, leading to the stimulation of both SkBr3 breast cancer cells and CAFs. Altogether, our results indicate that 3MC may engage both GPER and AHR transduction pathways toward breast cancer progression.

Role of EphA2-PI3K signaling in vasculogenic mimicry induced by cancer-associated fibroblasts in gastric cancer cells

Although erythropoietin-producing human hepatocellular receptor A2 (EphA2) signaling serves an important role in the tumor microenvironment, its contribution to vasculogenic mimicry (VM) formation in gastric cancer cells remains unclear. The aim of the present study was to investigate the role of EphA2 in VM formation induced by cancer-associated fibroblasts (CAFs). The conditioned medium of CAFs (CAF-CM) was prepared from 12 patients with gastric adenocarcinoma. VM was evaluated by the number of tubules and intersections in gastric cancer cells following CAF-CM treatment. The role of EphA2-phosphoinositide 3-kinase (PI3K) in VM was investigated using EphA2-targeted small interfering (si)RNAs (siEphA2), EphA2 inhibitors and PI3K-inhibitors. CAF-CM-induced VM formation was significantly associated with high protein expression levels of EphA2. EphA2 inhibitor and siEphA2 manipulation significantly decreased VM formation by CAF-CM. In siEphA2 cells, decreased expression levels of VM-associated proteins were observed. CAF-CM-induced VM formation was blocked by the PI3K-inhibitor. In conclusion, CAFs facilitate VM formation via EphA2-PI3K signaling in gastric cancer cells. Thus, EphA2-PI3K signaling may be required for CAF-promoted VM formation during gastric tumorigenesis.

Integrative Omic Profiling Reveals Unique Hypoxia Induced Signatures in Gastric Cancer Associated Myofibroblasts

Although hypoxia is known to contribute to several aspects of tumour progression, relatively little is known about the effects of hypoxia on cancer-associated myofibroblasts (CAMs), or the consequences that conditional changes in CAM function may have on tumour development and metastasis. To investigate this issue in the context of gastric cancer, a comparative multiomic analysis was performed on populations of patient-derived myofibroblasts, cultured under normoxic or hypoxic conditions. Data from this study reveal a novel set of CAM-specific hypoxia-induced changes in gene expression and secreted proteins. Significantly, these signatures are not observed in either patient matched adjacent tissue myofibroblasts (ATMs) or non-cancer associated normal tissue myofibroblasts (NTMs). Functional characterisation of different myofibroblast populations shows that hypoxia-induced changes in gene expression not only enhance the ability of CAMs to induce cancer cell migration, but also confer pro-tumorigenic (CAM-like) properties in NTMs. This study provides the first global mechanistic insight into the molecular changes that contribute to hypoxia-induced pro-tumorigenic changes in gastric stromal myofibroblasts.

Analysis of Extracellular Vesicles in Gastric Juice from Gastric Cancer Patients

Extracellular vesicles (EVs) are secretory membrane vesicles containing lipids, proteins, and nucleic acids; they function in intercellular transport by delivering their components to recipient cells. EVs are observed in various body fluids, i.e., blood, saliva, urine, amniotic fluid, and ascites. EVs secreted from cancer cells play important roles in the formation of their environment, including fibrosis, angiogenesis, evasion of immune surveillance, and even metastasis. However, EVs in gastric juice (GJ-EVs) have been largely unexplored. In this study, we sought to clarify the existence of GJ-EVs derived from gastric cancer patients. GJ-EVs were isolated by the ultracentrifuge method combined with our own preprocessing from gastric cancer (GC) patients. We verified GJ-EVs by morphological experiments, i.e., nanoparticle tracking system analysis and electron microscopy. In addition, protein and microRNA markers of EVs were examined by Western blotting analysis, Bioanalyzer, or quantitative reverse transcription polymerase chain reaction. GJ-EVs were found to promote the proliferation of normal fibroblast cells. Our findings suggest that isolates from the GJ of GC patients contain EVs and imply that GJ-EVs partially affect their microenvironments and that analysis using GJ-EVs from GC patients will help to clarify the pathophysiology of GC.

miR-338-3p Is Regulated by Estrogens through GPER in Breast Cancer Cells and Cancer-Associated Fibroblasts (CAFs)

Estrogens acting through the classic estrogen receptors (ERs) and the G protein estrogen receptor (GPER) regulate the expression of diverse miRNAs, small sequences of non-coding RNA involved in several pathophysiological conditions, including breast cancer. In order to provide novel insights on miRNAs regulation by estrogens in breast tumor, we evaluated the expression of 754 miRNAs by TaqMan Array in ER-negative and GPER-positive SkBr3 breast cancer cells and cancer-associated fibroblasts (CAFs) upon 17β-estradiol (E2) treatment. Various miRNAs were regulated by E2 in a peculiar manner in SkBr3 cancer cells and CAFs, while miR-338-3p displayed a similar regulation in both cell types. By METABRIC database analysis we ascertained that miR-338-3p positively correlates with overall survival in breast cancer patients, according to previous studies showing that miR-338-3p may suppress the growth and invasion of different cancer cells. Well-fitting with these data, a miR-338-3p mimic sequence decreased and a miR-338-3p inhibitor sequence rescued the expression of genes and the proliferative effects induced by E2 through GPER in SkBr3 cancer cells and CAFs. Altogether, our results provide novel evidence on the molecular mechanisms by which E2 may regulate miR-338-3p toward breast cancer progression.

Fluorescent contrast agents for tumor surgery

Cancer is a leading cause of cases of mortality worldwide. The most effective method to cure solid tumors is surgery. Every year, >50% of cancer patients receive surgery to remove solid tumors. Surgery may increase the cure rate of most solid tumors by 4–11 fold. Surgery has many challenges, including identifying small lesions, locating metastases and confirming complete tumor removal. Fluorescence guidance describes a new approach to improve surgical accuracy. Near-infrared fluorescence imaging allows for real-time early diagnosis and intraoperative imaging of lesion tissue. The results of previous preclinical studies in the field of near-infrared fluorescence imaging are promising. This review provides examples introducing the three kinds of fluorescent dyes: The passive fluorescent dye indocyanine green, which has been approved by the Food and Drug Administration for clinical use in the USA, the fluorescent prodrug 5-aminolevulinic acid, a porphyrin precursor in the heme synthesis, and biomarker-targeted fluorescent dyes, which allow conjugation to different target sites.

Cancer-associated fibroblasts promote gastric tumorigenesis through EphA2 activation in a ligand-independent manner

PURPOSE

Under physiologic conditions, the binding of erythropoietin-producing hepatocellular (Eph) A2 receptor and its ligand ephrinA1 results in decreased EphA2 level and tumor suppression. However, EphA2 and ephrinA1 are highly expressed in human cancers including gastric adenocarcinoma. In this study, we tested our hypothesis that cancer-associated fibroblasts (CAFs) promote gastric tumorigenesis through EphA2 signaling in a ligand-independent manner.

METHODS

Expression of EphA2 protein in primary tumor tissues of 91 patients who underwent curative surgery for gastric adenocarcinoma was evaluated by immunohistochemistry and western blotting. Conditioned medium of cancer-associated fibroblasts (CAF-CM) was used to evaluate the tumorigenic effect of CAFs on gastric cancer cell lines. Epithelial-mesenchymal transition (EMT), cell proliferation, migration, and invasion were assessed. EphrinA1-Fc ligand was used to determine the suppressor role of EphA2 receptor-ligand binding.

RESULTS

CAF-CM-induced EMT and promoted cancer cell motility even without cell-cell interaction. Treatment with a selective EphA2 inhibitor (ALW-II-41-27) or EphA2-targeted siRNA markedly reduced CAF-CM-induced gastric tumorigenesis. EphrinA1-Fc ligand treatment showing ligand-dependent tumor suppression diminished the EphA2 expression and EMT progression. In contrast, ephrinA1-targeted siRNA did not significantly affect CAF-CM-mediated increases in EphA2 expression and EMT progression. Treatment with VEGF showed effects like CAF-CM in terms of EphA2 activation and EMT progression.

CONCLUSION

CAFs may contribute to gastric tumorigenesis by activating EphA2 signaling pathway in a ligand-independent manner. Our results suggest that ligand-independent activation of EphA2 was triggered by VEGF released from CAF-CM. Our result may partially explain why ligand-dependent tumor suppressor roles of EphA2 are not evident in gastric cancer despite the prominent level of ephrinA1.

miR-221 stimulates breast cancer cells and cancer-associated fibroblasts (CAFs) through selective interference with the A20/c-Rel/CTGF signaling

Background

MicroRNA (miRNAs) are non-coding small RNA molecules that regulate gene expression by inhibiting the translation of target mRNAs. Among several dysregulated miRNAs in human cancer, the up-regulation of miR-221 has been associated with development of a variety of hematologic and solid malignancies. In this study, we investigated the involvement of miR-221 in breast cancer.

Methods

TaqMan microRNA assay was used to detect the miR-221 levels in normal cells and in MDA-MB 231 and SkBr3 breast cancer cells as well as in main players of the tumor microenvironment, namely cancer-associated fibroblasts (CAFs). miR-221 mimic sequence and locked nucleic acid (LNA)-i-miR-221 construct were used to induce or inhibit, respectively, the miR-221 expression in cells used. Quantitative PCR and western blotting analysis were performed to evaluate the levels of the miR-221 target gene A20 (TNFAIP3), as well as the member of the NF-kB complex namely c-Rel and the connective tissue growth factor (CTGF). Chromatin immunoprecipitation (ChIP) assay was performed to ascertain the recruitment of c-Rel to the CTFG promoter. Finally, the cell growth and migration in the presence of LNA-i-miR-221 or silencing c-Rel and CTGF by specific short hairpin were assessed by cell count, colony formation and boyden chambers assays. Statistical analysis was performed by ANOVA.

Results

We first demonstrated that LNA-i-miR-221 inhibits both endogenous and ectopic expression of miR-221 in our experimental models. Next, we found that the A20 down-regulation, as well as the up-regulation of c-Rel induced by miR-221 were no longer evident using LNA-i-miR-221. Moreover, we established that the miR-221 dependent recruitment of c-Rel to the NF-kB binding site located within the CTGF promoter region is prevented by using LNA-i-miR-221. Furthermore, we determined that the up-regulation of CTGF mRNA and protein levels by miR-221 is no longer evident using LNA-i-miR221 and silencing c-Rel. Finally, we assessed that cell growth and migration induced by miR-221 in MDA-MB 231 and SkBr3 breast cancer cells as well as in CAFs are abolished by LNAi-miR-221 and silencing c-Rel or CTGF.

Conclusions

Overall, these data provide novel insights into the stimulatory action of miR-221 in breast cancer cells and CAFs, suggesting that its inhibition may be considered toward targeted therapeutic approaches in breast cancer patients.

Exosomes Induce Fibroblast Differentiation into Cancer-Associated Fibroblasts through TGFβ Signaling

A particularly important tumor microenvironment relationship exists between cancer cells and surrounding stromal cells. Fibroblasts, in response to cancer cells, become activated and exhibit myofibroblastic characteristics that favor invasive growth and metastasis. However, the mechanism by which cancer cells promote activation of healthy fibroblasts into cancer-associated fibroblasts (CAF) is still not well understood. Exosomes are nanometer-sized vesicles that shuttle proteins and nucleic acids between cells to establish intercellular communication. Here, bladder cancer-derived exosomes were investigated to determine their role in the activation of healthy primary vesical fibroblasts. Exosomes released by bladder cancer cells are internalized by fibroblasts and promoted the proliferation and expression of CAF markers. In addition, cancer cell-derived exosomes contain TGFβ and in exosome-induced CAFs SMAD-dependent signaling is activated. Furthermore, TGFβ inhibitors attenuated CAF marker expression in healthy fibroblasts. Therefore, these data demonstrate that bladder cancer cells trigger the differentiation of fibroblasts to CAFs by exosomes-mediated TGFβ transfer and SMAD pathway activation. Finally, exosomal TGFβ localized inside the vesicle and contributes 53.4% to 86.3% of the total TGFβ present in the cancer cell supernatant. This study highlights a new function for bladder cancer exosomes as novel modulators of stromal cell differentiation.Implication: This study identifies exosomal TGFβ as new molecular mechanism involved in cancer-associated fibroblast activation. Mol Cancer Res; 16(7); 1196-204. ©2018 AACR.

DNA methylation in the tumor microenvironment

The tumor microenvironment (TME) plays an important role in supporting cancer progression. The TME is composed of tumor cells, the surrounding tumor-associated stromal cells, and the extracellular matrix (ECM). Crosstalk between the TME components contributes to tumorigenesis. Recently, one of our studies showed that pancreatic ductal adenocarcinoma (PDAC) cells can induce DNA methylation in cancer-associated fibroblasts (CAFs), thereby modifying tumor-stromal interactions in the TME, and subsequently creating a TME that supports tumor growth. Here we summarize recent studies about how DNA methylation affects tumorigenesis through regulating tumor-associated stromal components including fibroblasts and immune cells. We also discuss the potential for targeting DNA methylation for the treatment of cancers.

Nanoparticles for modulating tumor microenvironment to improve drug delivery and tumor therapy

Tumor microenvironment (TME) plays a critical role in tumorigenesis, tumor invasion and metastasis. TME is composed of stroma, endothelial cells, pericytes, fibroblasts, smooth muscle cells, and immune cells, which is characterized by hypoxia, acidosis, and high interstitial fluid pressure. Due to the important role of TME, we firstly reviewed the composition of TME and discussed the impact of TME on tumor progression, drug and nanoparticle delivery. Next, we reviewed current strategies developed to modulate TME, including modulating tumor vasculature permeability, tumor associated macrophage phenotypes, tumor associated fibroblasts, tumor stroma components, tumor hypoxia, and multiple interventions simultaneously. Also, potential problems and future directions of TME modulation strategy have been discussed.

Hyaluronan synthase 2 expressed by cancer-associated fibroblasts promotes oral cancer invasion

BACKGROUND

Hyaluronan synthases (HAS) control the biosynthesis of hyaluronan (HA) and critically modulate the tumor microenviroment. Cancer-associated fibroblasts (CAFs) affect the progression of a tumor by remolding the matrix. However, little is known about the role of HAS from CAFs in this process. This study aimed to determine the role of hyaluronan synthase 2 (HAS2) from CAFs in the progression of oral squamous cell carcinoma (OSCC) invasion.

METHODS

HAS isoforms 1, 2, and 3 in paired sets of CAFs and normal fibroblasts (NFs) were examined by real-time PCR, and the expression of HAS2 and α-SMA in OSCC tissue sections was further evaluated using immunohistochemical staining. Furthermore, we used a conditioned culture medium model to evaluate the effects of HAS2 from CAFs on the invasion and epithelial-mesenchymal transition (EMT) of the oral cancer cells Cal27. Finally, we compared the expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) between CAFs and NF, and between CAFs with or without HAS2 knockdown using an antibody array and western blotting.

RESULTS

CAFs expressed higher levels of HAS2 than the paired NFs. HAS2 expression was consistent with α-SMA-positive myofibroblasts in the stroma of OSCC, and these were significantly correlated advanced clinical stages and cervical lymph node metastasis. Knocking down HAS2 with a specific siRNA or treatment with a HAS inhibitor markedly attenuated CAF-induced invasion and EMT of Cal27 cells. Higher MMP1 and lower TIMP1 levels were detected in the supernatants of CAFs relative to NFs. Knocking down HAS2 could decrease the expression of MMP1 and increase that of TIMP1 in CAFs.

CONCLUSIONS

HAS2 is one of the key regulators responsible for CAF-mediated OSCC progression and acts by modulating the balance of MMP1 and TIMP1.

Galectin-1 from cancer-associated fibroblasts induces epithelial-mesenchymal transition through β1 integrin-mediated upregulation of Gli1 in gastric cancer

BACKGROUND

Gastric cancer (GC) is characterized by the excessive deposition of extracellular matrix, which is thought to contribute to this tumor's malignant behavior. Epithelial-mesenchymal transition (EMT) is regarded as a crucial contributing factor to cancer progression. Galectin-1 (Gal-1), a β-galactoside-binding protein abundantly expressed in activated cancer-associated fibroblasts (CAFs), has been reported to be involved in GC progression and metastasis by binding to β1 integrin, which, in turn, can bind to matrix proteins and activate intracellular cascades that mediate EMT. Increasing evidence suggests that abnormal activation of the hedgehog (Hh) signaling pathway enhances GC cell migration and invasion. The purpose of our study is to explore the role of Gal-1 in the GC progression and metastasis as well as the regulatory mechanism.

METHODS

We hypothesized that Gal-1 binding to β1 integrin would lead to paracrine signaling between CAFs and GC cells, mediating EMT by upregulating Gli1. Invasion and metastasis effects of the Gal-1 and Gli1 were evaluated using wound healing and invasion assay following transfection with mimics. Additionally, to facilitate the delineation of the role of the Hh signaling in GC, we monitored the expression level of associated proteins. We also evaluated the effects of β1 integrin on these processes. Furthermore, Gal-1 and Gli1 expression in GC patient samples were examined by immunohistochemistry and western blot to determine the correlation between their expression and clinicopathologic characteristics. The Kaplan-Meier method and Cox proportional hazards model were used to analyze the relationship of expression with clinical outcomes.

RESULTS

Gal-1 was found to induce EMT, GC cell migration and invasion. Further data showed that Gal-1 up-regulated Gli1 expression. β1 integrin was responsible for Gal-1-induced Gli1 expression and EMT. In clinical GC tissue, it confirmed a positive relationship between Gal-1 and Gli1 expression. Importantly, their high expression is correlated to poor prognosis.

CONCLUSION

Gal-1 from CAFs binds to a carbohydrate structure in β1 integrin and plays an important role in the development of GC by inducing GC metastasis and EMT through targeting Gli1. This study highlights the potential therapeutic value of Gal-1 for suppression of GC metastasis.

Physiological, Tumor, and Metastatic Niches: Opportunities and Challenges for Targeting the Tumor Microenvironment

The primary tumor niche and the related but distinct premetastatic/metastatic niche comprise a number of essential players, including immune cells, stromal cells, and extracellular matrix. The cross-talk between these components is key to tumor progression. Many of these cell types and signaling pathways in the tumor microenvironment also are found in physiological and stem cell niches, such as the bone marrow, colonic crypt, and skin bulge. Here they play tightly regulated roles in wound healing and tissue homeostasis. Understanding the similarities and differences between these distinct niches may better inform our ability to therapeutically target the tumor microenvironment. In this review we discuss a number of tumor and metastatic niche components as they relate to stem cell niches and highlight potential therapeutic strategies in pediatric cancers.

Potential of activatable FAP-targeting immunoliposomes in intraoperative imaging of spontaneous metastases

Despite intensive research and medical advances met, metastatic disease remains the most common cause of death in cancer patients. This results from late diagnosis, poor therapeutic response and undetected micrometastases and tumor margins during surgery. One approach to overcome these challenges involves fluorescence imaging, which exploits the properties of fluorescent probes for diagnostic detection of molecular structures at the onset of transformation and for intraoperative detection of metastases and tumor margins in real time. Considering these benefits, many contrast agents suitable for fluorescence imaging have been reported. However, most reports only demonstrate the detection of primary tumors and not the detection of metastases or their application in models of image-guided surgery. In this work, we demonstrate the influence of fibroblast activation protein (FAP) on the metastatic potential of fibrosarcoma cells and elucidate the efficacy of activatable FAP-targeting immunoliposomes (FAP-IL) for image-guided detection of the spontaneous metastases in mice models. Furthermore, we characterized the biodistribution and cellular localization of the liposomal fluorescent components in mice organs and traced their excretion over time in urine and feces. Taken together, activatable FAP-IL enhances intraoperative imaging of metastases. Their high accumulation in metastases, subsequent localization in the bile canaliculi and liver kupffer cells and suitable excretion in feces substantiates their potency as contrast agents for intraoperative imaging.

Cancer-associated fibroblasts promote angiogenesis in gastric cancer through galectin-1 expression

BACKGROUND

Galectin-1, an evolutionarily conserved glycan-binding protein with angiogenic potential, was recently identified as being overexpressed in cancer-associated fibroblasts (CAFs) of gastric cancer. The role of endogenous CAF-derived galectin-1 on angiogenesis in gastric cancer and the mechanism involved remain unknown.

METHODS

Immunohistochemical staining was used to investigate the correlation between galectin-1 and vascular endothelial growth factor (VEGF) and CD31 expression in gastric cancer tissues and normal gastric tissues. Galectin-1 was knocked down in CAFs isolated from gastric cancer using small interfering ribonucleic acid (RNA), or overexpressed using recombinant lentiviruses, and the CAFs were co-cultured with human umbilical vein endothelial cells (HUVECs) or cancer cells. Subsequently, proliferation, migration, tube formation, and VEGF/VEGF receptor (VEGFR) 2 expression were detected. The role of CAF-derived galectin-1 in tumor angiogenesis in vivo was studied using the chick chorioallantoic membrane (CAM) assay.

RESULTS

Galectin-1 was highly expressed in the CAFs and was positively associated with VEGF and CD31 expression. In the co-culture, high expression of galectin-1 in the CAFs increased HUVEC proliferation, migration, tube formation, and VEGFR2 phosphorylation and enhanced VEGF expression in gastric cancer cells. The CAM assay indicated that high expression of galectin-1 in the CAFs accelerated tumor growth and promoted angiogenesis. In contrast, galectin-1 knockdown in the CAFs significantly inhibited this effect.

CONCLUSION

CAF-derived galectin-1 significantly promotes angiogenesis in gastric cancer and may be a target for angiostatic therapy.

Quantitative changes in tumor-associated M2 macrophages characterize cholangiocarcinoma and their association with metastasis

The tumor microenvironment (TME) includes numerous non-neoplastic cells such as leukocytes and fibroblasts that surround the neoplasm and influence its growth. Tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs) are documented as key players in facilitating cancer appearance and progression. Alteration of the macrophage (CD68, CD163) and fibroblast (α-SMA, FSP-1) cells in Opisthorchis viverrini (Ov)-induced cholangiocarcinoma (CCA) was here assessed using liver tissues from an established hamster model and from 43 human cases using immunohistochemistry. We further investigated whether M2-activated TAMs influence CCA cell migration ability by wound healing assay and Western blot analysis. Macrophages and fibroblasts change their phenotypes to M2-TAMs (CD68+, CD163+) and CAFs (α-SMA+, FSP-1+), respectively in the early stages of carcinogenesis. Interestingly, a high density of the M2-TAMs CCA in patients is significantly associated with the presence of extrahepatic metastases (p=0.021). Similarly, CD163+ CCA cells are correlated with metastases (p=0.002), and they may be representative of an epithelial-to-mesenchymal transition (EMT) with increased metastatic activity. We further showed that M2-TAM conditioned medium can induce CCA cell migration as well as increase N-cadherin expression (mesenchymal marker). The present work revealed that significant TME changes occur at an early stage of Ov-induced carcinogenesis and that M2-TAMs are key factors contributing to CCA metastasis, possibly via EMT processes.

Microenvironmental interactions and expression of molecular markers associated with epithelial-to-mesenchymal transition in colorectal carcinoma

The tumor microenvironment is known to play a critical role in tumor progression, invasion and metastasis. The epithelial-to-mesenchymal transition (EMT) is understood as a process of tumor invasion and metastasis. Therefore, we investigated the relation between the EMT and the microenvironment of colorectal carcinoma (CRC). The histological features and expression of EMT markers in tumor cells and surrounded stromal cells were obtained from the surgically resected tissues of 39 patients using microscopic review and immunohistochemistry. The loss of expression of E-cadherin was more prominent in the invasive front of tumor than the surface, where α-smooth muscle actin-positive carcinoma-associated fibroblasts (CAFs) are accumulated. The signaling molecules of the Wnt and TGF-β1-Smad pathway were expressed more frequently in the tumor cells and/or CAFs of the invasive margin than those of the tumor surface. The expressions of related transcription factors, such as SNAIL and ZEB1, were increased in the tumor cells and CAFs. The process of EMT may be activated in the tumor margin of CRC under the control of CAFs. Related signaling molecules and transcription factors might be induced by paracrine effects of the surrounding CAFs.

Cancer-associated fibroblasts provide a suitable microenvironment for tumor development and progression in oral tongue squamous cancer

Background

Oral tongue squamous cell carcinoma (OTSCC) is still associated with a poor prognosis due to local recurrence and metastasis. Cancer-associated fibroblasts (CAFs) play an important role in the complex processes of cancer stroma interaction and tumorigenesis. This study aims to determine the role of CAFs in the development and progression of OTSCC.

Methods

Immunohistochemistry was performed to evaluate the frequency and distribution of CAFs in 178 paraffin specimens from patients with OTSCC. Immunofluorescence, a cell proliferation assay, flow cytometry, migration and invasion assays and western blot analysis were used to study the effects of CAFs and the corresponding conditioned medium (CM) on the proliferation and invasion of OTSCC cell lines.

Results

Statistical analysis showed a strong correlation between the frequency and distribution of CAFs and the clinicopathological characteristics of patients with cN0 OTSCC, including pathological stage (P = 0.001), T classification (P = 0.001), and N classification (P = 0.009). Survival analysis demonstrated a negative correlation of the frequency and distribution of CAFs with the overall survival and disease-free survival of patients with cN0 tongue squamous cell cancer (P = 0.009, 0.002, respectively); Cox regression analysis showed that the presence of CAFs (relative risk: 2.113, CI 1.461–3.015, P = 0.023) is an independent prognostic factor. A functional study demonstrated that CAFs and CM from CAFs could promote the growth, proliferation, mobility, invasion and even Epithelial Mesenchymal Transition (EMT) of OTSCC cells compared with NFs and CM from NFs.

Conclusions

CAFs were an independent prognostic factor for patients with OTSCC. Compared with NFs, CAFs and their CM have the ability to promote the growth, proliferation, metastasis and even EMT of OTSCC cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0551-8) contains supplementary material, which is available to authorized users.

Bone marrow derived "fibrocytes" contribute to tumor proliferation and fibrosis in gastric cancer

BACKGROUND

Cancer-associated fibroblasts (CAFs) in the stroma are considered to play important roles for gastric cancer proliferation, invasion, and fibrosis, but the source of CAFs and their interaction with cancer cells in the microenvironment have not been fully determined. Here we elucidated the role of bone marrow-derived cells, fibrocytes, in development of gastric cancers, as represented by scirrhous gastric cancer.

MATERIALS AND METHODS

In co-culturing MKN45 gastric cancer cells and purified fibrocytes from healthy volunteers, migration and endothelial mesenchymal transition associated gene expression were evaluated using western blot analysis. Also, mouse xenograft models of MKN45 with or without fibrocytes were conducted to investigate their tumorigenicity and immunohistological differences of tumors.

RESULTS

Co-culture of fibrocytes with MKN45 resulted in morphological changes from cobblestone-shape to spindle-shape and enhanced expression of α-SMA and collagen type I in fibrocytes, suggesting that co-culture with gastric cancer cells may have induced the differentiation of fibrocytes to myofibroblasts. Furthermore, enhanced expression of SDF-1 in MKN45 and CXCR4 in fibrocytes were also determined. Mouse xenograft models inoculated with MKN45 and fibrocytes revealed significantly larger tumors than those inoculated with MKN45 cells alone, and the stroma in co-inoculated tumors consisted of myofibroblasts and fibrosis. Mouse-derived cells expressing both CD45 and type I collagen were also observed in co-inoculated tumors.

CONCLUSION

Fibrocytes derived from bone marrow may migrate into the microenvironment of gastric cancer by SDF-1/CXCR4 system, and enhance the tumor proliferation and fibrosis as CAFs.

Benchmarking of gastric cancer sensitivity to anti-cancer drugs ex vivo as a basis for drug selection in systemic and intraperitoneal therapy

Background

The choice of drugs for treatment of advanced gastric cancer (GC) is empirical. The purpose of the current study was to benchmark ex vivo the sensitivity of GC tumor cells from patients to standard cytotoxic and some newly introduced targeted drugs (TDs), as a basis for drug selection in the treatment of GC.

Methods

Tumor cell samples from patients with GC were analyzed for sensitivity to 5-fluorouracil, cisplatin, oxaliplatin, irinotecan, mitomycin C, doxorubicin and docetaxel as well as for the targeted drugs bortezomib, sorafenib, sunitinib and rapamycin using a short-term in vitro assay based on retention of viable tumor cells of fluorescent fluorescein. Samples of normal mononuclear cells, chronic lymphocytic leukemia, ovarian cancer and colorectal cancer were included for comparison.

Results

The GC samples were essentially as sensitive to the standard drugs and the TDs as those from colorectal cancer whereas the ovarian cancer samples were more sensitive. The individual GC samples varied considerably in sensitivity to increasing concentrations of the clinically used standard drugs. In GC, cisplatin was cross-resistant to oxaliplatin and 5-fluorouracil which, on the other hand, was not cross-resistant to the other cytotoxic drugs. The activity of sunitinib did not obviously correlate to that of the standard drugs.

Conclusion

Ex vivo assessment of drug sensitivity of tumor cells from patients with GC is feasible and may provide information that could be useful for selection of drugs for treatment. Drug sensitivity varies considerably between and within individual samples arguing for individualized selection of drugs for chemotherapy.

Expression of galectin-1 in carcinoma-associated fibroblasts promotes gastric cancer cell invasion through upregulation of integrin β1

Increased expression of galectin-1 (Gal-1) in carcinoma-associated fibroblasts (CAFs) has been reported to correlate with progression and prognosis in many cancers. However, rarely have reports sought to determine whether high Gal-1 expression in CAFs in gastric cancer is involved in the tumor process, and the specific mechanism by which it promotes the evolution of gastric cancer is still unknown. In this study, we cultured gastric cancer CAFs, which showed strong expression of Gal-1, and established a co-culture system of CAFs with gastric cancer cells. Specific siRNA and in vitro migration and invasion assays were used to explore the effects of the interaction between Gal-1 expression of CAFs and gastric cancer cells on cell migration and invasion. We found that the overexpression of Gal-1 in CAFs enhanced gastric cancer cell migration and invasion, and these stimulatory effects could be blocked by specific siRNA which reduced the Gal-1 expression level. A set of cancer invasion-associated genes were then chosen to identify the possible mechanism of Gal-1-induced cell invasion. Among these genes, integrin β1 expression in cancer cells was considered to be associated with Gal-1 expression. Pre-blocking of the integrin β1 expression in gastric cancer cells with siRNA could interrupt the invasion-promoting effect of CAFs with high Gal-1 expression. Furthermore, immunohistochemical assay confirmed a positive correlation between Gal-1 and integrin β1 expression. Our results showed that high expression of Gal-1 in CAFs might facilitate gastric cancer cell migration and invasion by upregulating integrin β1 expression in gastric cancer.

MicroRNA-106b in cancer-associated fibroblasts from gastric cancer promotes cell migration and invasion by targeting PTEN

It is well established that the interaction between cancer cells and microenvironment has a critical role in tumor development, but the roles of miRNAs in this interaction are rarely known. Here, we have shown that miR-106b is up-regulated in cancer associated fibroblasts compared with normal fibroblasts established from patients with gastric cancer, the expression level of miR-106b is associated with poor prognosis of patients, and CAFs with down-regulated miR-106b could significantly inhibit gastric cancer cell migration and invasion by targeting PTEN. Taken together, these data suggest that miR-106b might be a novel candidate target for the treatment of gastric cancer.