Cancer-associated fibroblasts as abettors of tumor progression at the crossroads of EMT and therapy resistance

Bone marrow mesenchymal/fibroblastic stromal cells induce a distinctive EMT-like phenotype in AML cells

The development of epithelial-to-mesenchymal transition (EMT) like features is emerging as a critical factor involved in the pathogenesis of acute myeloid leukaemia (AML). However, the extracellular signals and the signalling pathways in AML that may regulate EMT remain largely unstudied. We found that the bone marrow (BM) mesenchymal/fibroblastic cell line HS5 induces an EMT-like migratory phenotype in AML cells. AML cells underwent a strong increase of vimentin (VIM) levels that was not mirrored to the same extent by changes of expression of the other EMT core proteins SNAI1 and SNAI2. We validated these particular pattern of co-expression of core-EMT markers in AML cells by performing an in silico analysis using datasets of human tumours. Our data showed that in AML the expression levels of VIM does not completely correlate with the co-expression of core EMT markers observed in epithelial tumours. We also found that vs epithelial tumours, AML cells display a distinct patterns of co-expression of VIM and the actin binding and adhesion regulatory proteins that regulate F-actin dynamics and integrin-mediated adhesions involved in the invasive migration in cells undergoing EMT. We conclude that the BM stroma induces an EMT related pattern of migration in AML cells in a process involving a distinctive regulation of EMT markers and of regulators of cell adhesion and actin dynamics that should be further investigated. Understanding the tumour specific signalling pathways associated with the EMT process may contribute to the development of new tailored therapies for AML as well as in different types of cancers.

Mesenchymal-like Tumor Cells and Myofibroblastic Cancer-Associated Fibroblasts Are Associated with Progression and Immunotherapy Response of Clear Cell Renal Cell Carcinoma

Immune checkpoint inhibitors (ICI) represent the cornerstone for the treatment of patients with metastatic clear cell renal cell carcinoma (ccRCC). Despite a favorable response for a subset of patients, others experience primary progressive disease, highlighting the need to precisely understand the plasticity of cancer cells and their cross-talk with the microenvironment to better predict therapeutic response and personalize treatment. Single-cell RNA sequencing of ccRCC at different disease stages and normal adjacent tissue (NAT) from patients identified 46 cell populations, including 5 tumor subpopulations, characterized by distinct transcriptional signatures representing an epithelial-to-mesenchymal transition gradient and a novel inflamed state. Deconvolution of the tumor and microenvironment signatures in public data sets and data from the BIONIKK clinical trial (NCT02960906) revealed a strong correlation between mesenchymal-like ccRCC cells and myofibroblastic cancer-associated fibroblasts (myCAF), which are both enriched in metastases and correlate with poor patient survival. Spatial transcriptomics and multiplex immune staining uncovered the spatial proximity of mesenchymal-like ccRCC cells and myCAFs at the tumor-NAT interface. Moreover, enrichment in myCAFs was associated with primary resistance to ICI therapy in the BIONIKK clinical trial. These data highlight the epithelial-mesenchymal plasticity of ccRCC cancer cells and their relationship with myCAFs, a critical component of the microenvironment associated with poor outcome and ICI resistance.

SIGNIFICANCE

Single-cell and spatial transcriptomics reveal the proximity of mesenchymal tumor cells to myofibroblastic cancer-associated fibroblasts and their association with disease outcome and immune checkpoint inhibitor response in clear cell renal cell carcinoma.

Biological differences between normal and cancer-associated fibroblasts in breast cancer

Background

Cancer-associated fibroblasts (CAFs) constitute the primary constituents of the tumor microenvironment (TME) and exert significant influences on cancer progression. However, adequate comprehension of CAF profiles in breast cancer, as well as the precise mechanisms underlying their promotion of cancer, remains lacking.

Objectives

To discerns the biological differences between normal fibroblasts (NFs) and CAFs in breast cancer and explore the underlying mechanism.

Methods

Three pairs of CAFs and NFs were isolated from breast cancer patients of diverse subtypes who had not undergone prior radiotherapy or chemotherapy. Morphological characteristics of CAFs and NFs were assessed through optical and electron microscopy, their biological attributes were examined using cell counting kits and transwell assays, and their impact on breast cancer cells was simulated using a coculture system. Furthermore, the miRNA profiles of CAFs and NFs were sequenced via an Illumina HiSeq 2500 platform.

Results

CAFs exhibited higher growth rate and motility than NFs and a stronger potential to promote the malignancy of breast cancer cells. RNA sequencing of both NFs and CAFs revealed differentially expressed miRNAs with notable variability among distinct patients within their NFs and CAFs, while the enrichment of the target genes of differentially expressed miRNAs within both GO terms and KEGG pathways demonstrated significant similarity across patients with different profiles.

Conclusion

CAFs have greater malignancy and higher potential to influence the growth, migration, invasion and chemoresistance of cocultured breast cancer cells than NFs. In addition, the miRNAs that are differentially expressed in CAFs when compared to NFs display substantial variability across patients with distinct breast cancer subtypes, while the enrichment of target genes regulated by these miRNAs, within GO terms and KEGG pathways, remains remarkably consistent among patients with varying profiles.

Superiority of [68Ga]Ga-DOTA-FAPI-04 PET/CT to [18F]FDG PET/CT in the evaluation of thymic epithelial tumours

PURPOSE

The purpose of this study is to compare the ability of [68Ga]Ga-DOTA-FAPI-04 PET/CT and [18F]FDG PET/CT to stratify the malignancy and invasiveness of thymic epithelial tumours (TETs).

METHODS

From April 2021 to November 2022, participants with suspected TETs confirmed by histopathology or follow-up imaging were prospectively analysed. All participants underwent [18F]FDG and [68Ga]Ga-DOTA-FAPI-04 PET/CT within 1 week. Clinical characteristics, CT features, and metabolic parameters (maximum standardized uptake value [SUVmax] and tumour-to-mediastinum ratio [TMR]) of subjects with different pathological types and stages were compared. The diagnostic capacities of [18F]FDG and [68Ga]Ga-DOTA-FAPI-04 PET/CT were compared using receiver operating characteristic (ROC) curves and McNemar's test.

RESULTS

Fifty-seven participants were included. [68Ga]Ga-DOTA-FAPI-04 PET/CT was superior to [18F]FDG PET/CT in differentiating thymomas from thymic carcinomas (TCs) (AUC: 0.99 vs. 0.90, P = 0.02). Logistic regression revealed that SUVmax-FAPI (P = 0.04) was a significant predictive factor for TCs. SUVmax-FAPI and TMR-FAPI showed an excellent ability to differentiate low-risk thymomas (types A, AB, and B1), high-risk thymomas (types B2 and B3), and TCs (both P < 0.001). In thymomas, only SUVmax-FAPI (P < 0.001), TMR-FAPI (P < 0.001), and nonsmooth edges (P = 0.02) were significantly higher in the advanced-stage (Masaoka-Koga [MK] stage III/IV) group than in the early-stage group (MK stage I/II). Compared with [18F]FDG PET/CT, [68Ga]Ga-DOTA-FAPI-04 PET/CT showed significantly higher specificity (67% [46 of 69] vs. 93% [64 of 69], P < 0.001) in the detection of lymph node metastases and higher sensitivity (49% [19 of 39] vs. 97% [38 of 39], P < 0.001) in evaluating distant metastases. Both SUVmax-FAPI and TMR-FAPI were correlated with FAP expression (both r = 0.843, P < 0.001).

CONCLUSION

[68Ga]Ga-DOTA-FAPI-04 PET/CT was superior to [18F]FDG PET/CT in evaluating the World Health Organization (WHO) classification, MK staging, and metastatic status of TETs.

TRIAL REGISTRATION

ChiCTR2000038080, registration date 2020-09-09, https://www.chictr.org.cn/com/25/showproj.aspx?proj=61192.

Molecular mechanisms of ROS-modulated cancer chemoresistance and therapeutic strategies

Drug resistance is the main obstacle to achieving a cure in many cancer patients. Reactive oxygen species (ROS) are master regulators of cancer development that act through complex mechanisms. Remarkably, ROS levels and antioxidant content are typically higher in drug-resistant cancer cells than in non-resistant and normal cells, and have been shown to play a central role in modulating drug resistance. Therefore, determining the underlying functions of ROS in the modulation of drug resistance will contribute to develop therapies that sensitize cancer resistant cells by leveraging ROS modulation. In this review, we summarize the notable literature on the sources and regulation of ROS production and highlight the complex roles of ROS in cancer chemoresistance, encompassing transcription factor-mediated chemoresistance, maintenance of cancer stem cells, and their impact on the tumor microenvironment. We also discuss the potential of ROS-targeted therapies in overcoming tumor therapeutic resistance.

Engineered Plant-Derived Nanovesicles Facilitate Tumor Therapy: Natural Bioactivity Plus Drug Controlled Release Platform

Tumors are the second-most common disease in the world, killing people at an alarming rate. As issues with drug resistance, lack of targeting, and severe side effects are revealed, there is a growing demand for precision-targeted drug delivery systems. Plant-derived nanovesicles (PDNVs), which arecomposed of proteins, lipids, RNA, and metabolites, are widely distributed and readily accessible. The potential for anti-proliferative, pro-apoptotic, and drug-resistant-reversing effects on tumor cells, as well as the ability to alter the tumor microenvironment (TME) by modulating tumor-specific immune cells, make PDNVs promising anti-tumor therapeutics. With a lipid bilayer structure that allows drug loading and a transmembrane capacity readily endocytosed by cells, PDNVs are also expected to become a new drug delivery platform. Exogenous modifications of PDNVs enhance their circulating stability, tumor targeting ability, high cell endocytosis rate, and controlled-release capacity. In this review, we summarize PDNVs' natural antitumor activity, as well as engineered PDNVs as efficient precision-targeted drug delivery tools that enhance therapeutic effects. Additionally, we discuss critical considerations related to the issues raised in this area, which will encourage researchers to improve PDNVs as better anti-tumor therapeutics for clinic applications.

Mechanisms of radiotherapy resistance and radiosensitization strategies for esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is the sixth most common cause of cancer-related mortality worldwide, with more than half of them occurred in China. Radiotherapy (RT) has been widely used for treating ESCC. However, radiation-induced DNA damage response (DDR) can promote the release of cytokines and chemokines, and triggers inflammatory reactions and changes in the tumor microenvironment (TME), thereby inhibiting the immune function and causing the invasion and metastasis of ESCC. Radioresistance is the major cause of disease progression and mortality in cancer, and it is associated with heterogeneity. Therefore, a better understanding of the radioresistance mechanisms may generate more reversal strategies to improve the cure rates and survival periods of ESCC patients. We mainly summarized the possible mechanisms of radioresistance in order to reveal new targets for ESCC therapy. Then we summarized and compared the current strategies to reverse radioresistance.

Correlation between [68Ga]Ga-FAPI-46 PET Imaging and HIF-1α Immunohistochemical Analysis in Cervical Cancer: Proof-of-Concept

Hypoxia leads to changes in tumor microenvironment (upregulated CAFs) with resultant aggressiveness. A key factor in the physiological response to hypoxia is hypoxia-inducible factor-1alpha (HIF-1α). [68Ga]Ga-FAPI PET imaging has been demonstrated in various cancer types. We hypothesized that [68Ga]Ga-FAPI PET may be used as an indirect tracer for mapping hypoxia by correlating the image findings to pathological analysis of HIF-1α expression. The [68Ga]Ga-FAPI PET/CT scans of women with cancer of the cervix were reviewed and the maximum and mean standardized uptake value (SUVmax and SUVmean) and FAPI tumor volume (FAPI-TV) were documented. Correlation analysis was performed between PET-derived parameters and immunohistochemical staining as well as between PET-derived parameters and the presence of metastasis. Ten women were included. All patients demonstrated tracer uptake in the primary site or region of the primary. All patients had lymph node metastases while only six patients had distant visceral or skeletal metastases. The mean SUVmax, SUVmean, and FAPI-TV was 18.89, 6.88, and 195.66 cm3, respectively. The average FAPI-TV for patients with additional sites of metastases was higher than those without. Immunohistochemistry revealed varying intensities of HIF-1α expression in all tested samples. There was a positive correlation between the presence of skeletal metastases and staining for HIF-1α (r=0.80;p=0.017). The presence of skeletal metastasis was correlated to the HIF-1⍺ staining (percentage distribution). Furthermore, the FAPI-TV was a better predictor of metastatic disease than the SUVmax.

Simultaneous isolation of hormone receptor-positive breast cancer organoids and fibroblasts reveals stroma-mediated resistance mechanisms

Recurrent hormone receptor-positive (HR+) breast cancer kills more than 600,000 women annually. Although HR+ breast cancers typically respond well to therapies, approximately 30% of patients relapse. At this stage, the tumors are usually metastatic and incurable. Resistance to therapy, particularly endocrine therapy is typically thought to be tumor intrinsic (e.g., estrogen receptor mutations). However, tumor-extrinsic factors also contribute to resistance. For example, stromal cells, such as cancer-associated fibroblasts (CAFs), residing in the tumor microenvironment, are known to stimulate resistance and disease recurrence. Recurrence in HR+ disease has been difficult to study due to the prolonged clinical course, complex nature of resistance, and lack of appropriate model systems. Existing HR+ models are limited to HR+ cell lines, a few HR+ organoid models, and xenograft models that all lack components of the human stroma. Therefore, there is an urgent need for more clinically relevant models to study the complex nature of recurrent HR+ breast cancer, and the factors contributing to treatment relapse. Here, we present an optimized protocol that allows a high take-rate, and simultaneous propagation of patient-derived organoids (PDOs) and matching CAFs, from primary and metastatic HR+ breast cancers. Our protocol allows for long-term culturing of HR+ PDOs that retain estrogen receptor expression and show responsiveness to hormone therapy. We further show the functional utility of this system by identifying CAF-secreted cytokines, such as growth-regulated oncogene α , as stroma-derived resistance drivers to endocrine therapy in HR+ PDOs.

TGF-β1 dominates stromal fibroblast-mediated EMT via the FAP/VCAN axis in bladder cancer cells

BACKGROUND

Bladder cancer is one of the most common malignant tumors of the urinary system and is associated with a poor prognosis once invasion and distant metastases occur. Epithelial-mesenchymal transition (EMT) drives metastasis and invasion in bladder cancer. Transforming growth factor β1 (TGF-β1) and stromal fibroblasts, especially cancer-associated fibroblasts (CAFs), are positive regulators of EMT in bladder cancer. However, it remains unclear how TGF-β1 mediates crosstalk between bladder cancer cells and CAFs and how it induces stromal fibroblast-mediated EMT in bladder cancer. We aimed to investigate the mechanism of TGF-β1 regulation of stromal fibroblast-mediated EMT in bladder cancer cells.

METHODS

Primary CAFs with high expression of fibroblast activation protein (FAP) were isolated from bladder cancer tissue samples. Subsequently, different conditioned media were used to stimulate the bladder cancer cell line T24 in a co-culture system. Gene set enrichment analysis, a human cytokine antibody array, and cytological assays were performed to investigate the mechanism of TGF-β1 regulation of stromal fibroblast-mediated EMT in bladder cancer cells.

RESULTS

Among the TGF-β family, TGF-β1 was the most highly expressed factor in bladder cancer tissue and primary stromal fibroblast supernatant. In the tumor microenvironment, TGF-β1 was mainly derived from stromal fibroblasts, especially CAFs. In stimulated bladder cells, stromal fibroblast-derived TGF-β1 promoted bladder cancer cell migration, invasion, and EMT. Furthermore, TGF-β1 promoted the activation of stromal fibroblasts, inducing CAF-like features, by upregulating FAP in primary normal fibroblasts and a normal fibroblast cell line. Stromal fibroblast-mediated EMT was induced in bladder cancer cells by TGF-β1/FAP. Versican (VCAN), a downstream molecule of FAP, plays an essential role in TGF-β1/FAP axis-induced EMT in bladder cancer cells. VCAN may also function through the PI3K/AKT1 signaling pathway.

CONCLUSIONS

TGF-β1 is a critical mediator of crosstalk between stromal fibroblasts and bladder cancer cells. We revealed a new mechanism whereby TGF-β1 dominated stromal fibroblast-mediated EMT of bladder cancer cells via the FAP/VCAN axis and identified potential biomarkers (FAP, VCAN, N-cadherin, and Vimentin) of bladder cancer. These results enhance our understanding of bladder cancer invasion and metastasis and provide potential strategies for diagnosis, treatment, and prognosis.

Mechanosensory feedback loops during chronic inflammation

Epithelial tissues are crucial to maintaining healthy organization and compartmentalization in various organs and act as a first line of defense against infection in barrier organs such as the skin, lungs and intestine. Disruption or injury to these barriers can lead to infiltration of resident or foreign microbes, initiating local inflammation. One often overlooked aspect of this response is local changes in tissue mechanics during inflammation. In this mini-review, we summarize known molecular mechanisms linking disruption of epithelial barrier function to mechanical changes in epithelial tissues. We consider direct mechanisms, such as changes in the secretion of extracellular matrix (ECM)-modulating enzymes by immune cells as well as indirect mechanisms including local activation of fibroblasts. We discuss how these mechanical changes can modulate local immune cell activity and inflammation and perturb epithelial homeostasis, further dysregulating epithelial barrier function. We propose that this two-way relationship between loss of barrier function and altered tissue mechanics can lead to a positive feedback loop that further perpetuates inflammation. We discuss this cycle in the context of several chronic inflammatory diseases, including inflammatory bowel disease (IBD), liver disease and cancer, and we present the modulation of tissue mechanics as a new framework for combating chronic inflammation.

Recent Advances on Cell Culture Platforms for In Vitro Drug Screening and Cell Therapies: From Conventional to Microfluidic Strategies

The clinical translations of drugs and nanomedicines depend on coherent pharmaceutical research based on biologically accurate screening approaches. Since establishing the 2D in vitro cell culture method, the scientific community has improved cell-based drug screening assays and models. Those advances result in more informative biochemical assays and the development of 3D multicellular models to describe the biological complexity better and enhance the simulation of the in vivo microenvironment. Despite the overall dominance of conventional 2D and 3D cell macroscopic culture methods, they present physicochemical and operational challenges that impair the scale-up of drug screening by not allowing a high parallelization, multidrug combination, and high-throughput screening. Their combination and complementarity with microfluidic platforms enable the development of microfluidics-based cell culture platforms with unequivocal advantages in drug screening and cell therapies. Thus, this review presents an updated and consolidated view of cell culture miniaturization's physical, chemical, and operational considerations in the pharmaceutical research scenario. It clarifies advances in the field using gradient-based microfluidics, droplet-based microfluidics, printed-based microfluidics, digital-based microfluidics, SlipChip, and paper-based microfluidics. Finally, it presents a comparative analysis of the performance of cell-based methods in life research and development to achieve increased precision in the drug screening process.

Expression Profile of Microenvironmental Factors in the Interface Zone of Colorectal Cancer: Histological-Stromal Biomarkers and Cancer Cell-Cancer-Associated Fibroblast-Related Proteins Combined for the Assessment of Tumor Progression

INTRODUCTION

The characterization of tumor microenvironment (TME) related factors and their impact on tumor progression have attracted much interest. We investigated cancer cells and cancer-associated fibroblasts (CAFs) to evaluate biomarkers that are associated with neoplastic progression, observing them in different interface zones of colorectal cancer.

METHODS

On 357 CRC tissue microarrays, using immunohistochemistry, we examined the associations of podoplanin and α-SMA expressed in cancer cells and CAFs and evaluated them in different areas: tumor core, invasive front, tumor budding, tumor-stroma ratio (TSR) scoring, and desmoplastic stroma.

RESULTS

CAFs expressing α-SMA were found in more than 90% of the cases. Podoplanin+ was detected in cancer cells and CAFs, with positivities of 38.6% and 70%, respectively. Higher α-SMA+ CAFs and podoplanin+ cancer cells were observed predominantly at the TSR score area: 94.3% and 64.3% of cases, respectively. The status of podoplanin in CAFs+ was higher in the desmoplastic area (71.6%). Stroma-high tumors showed increased expression of α-SMA and podoplanin in comparison with stroma-low tumors. The status of podoplanin in cancer cells was observed in association with lymphatic invasion and distant metastasis.

CONCLUSION

The substance of the CRC was composed predominantly of the surrounding stroma-α-SMA+ CAFs. Podoplanin expressed in the prognosticator zones was associated with unfavorable pathological features. The combination of histologic and protein-related biomarkers can result in a tool for the stratification of patients with CRC.

Involvement of FAM83 Family Proteins in the Development of Solid Tumors: An Update Review

FAM83 family members are a group of proteins that have been implicated in various solid tumors. In this updated review, we mainly focus on the cellular localization, molecular composition, and biological function of FAM83 family proteins in solid tumors. We discussed the factors that regulate abnormal protein expression and alterations in the functional activities of solid tumor cells (including non-coding microRNAs and protein modifiers) and potential mechanisms of tumorigenesis (including the MAPK, WNT, and TGF-β signaling pathways). Further, we highlighted the application of FAM83 family proteins in the diagnoses and treatment of different cancers, such as breast, lung, liver, and ovarian cancers from two aspects: molecular marker diagnosis and tumor drug resistance. We described the overexpression of FAM83 genes in various human malignant tumor cells and its relationship with tumor proliferation, migration, invasion, transformation, and drug resistance. Moreover, we explored the prospects and challenges of using tumor treatments based on the FAM83 proteins. Overall, we provide a theoretical basis for harnessing FAM83 family proteins as novel targets in cancer treatment. We believe that this review opens up open new directions for solid tumor treatment in clinical practice.

Cancer-associated fibroblasts refine the classifications of gastric cancer with distinct prognosis and tumor microenvironment characteristics

Background

Cancer-associated fibroblasts (CAFs) are essential tumoral components of gastric cancer (GC), contributing to the development, therapeutic resistance and immune-suppressive tumor microenvironment (TME) of GC. This study aimed to explore the factors related to matrix CAFs and establish a CAF model to evaluate the prognosis and therapeutic effect of GC.

Methods

Sample information from the multiply public databases were retrieved. Weighted gene co-expression network analysis was used to identify CAF-related genes. EPIC algorithm was used to construct and verify the model. Machine-learning methods characterized CAF risk. Gene set enrichment analysis was employed to elucidate the underlying mechanism of CAF in the development of GC.

Results

A three-gene (GLT8D2, SPARC and VCAN) prognostic CAF model was established, and patients were markedly divided according to the riskscore of CAF model. The high-risk CAF clusters had significantly worse prognoses and less significant responses to immunotherapy than the low-risk group. Additionally, the CAF risk score was positively associated with CAF infiltration in GC. Moreover, the expression of the three model biomarkers were significantly associated with the CAF infiltration. GSEA revealed significant enrichment of cell adhesion molecules, extracellular matrix receptors and focal adhesions in patients at a high risk of CAF.

Conclusion

The CAF signature refines the classifications of GC with distinct prognosis and clinicopathological indicators. The three-gene model could effectively aid in determining the prognosis, drug resistance and immunotherapy efficacy of GC. Thus, this model has promising clinical significance for guiding precise GC anti-CAF therapy combined with immunotherapy.

Activated breast stromal fibroblasts exhibit myoepithelial and mammary stem cells features

BACKGROUND

Active breast cancer-associated fibroblasts (CAFs) promote tumor growth and spread, and like tumor cells they are also heterogeneous with various molecular sub-types and different pro-tumorigenic capacities.

METHODS

We have used immunoblotting as well as quantitative RT-PCR to assess the expression of various epithelial/mesenchymal as well as stemness markers in breast stromal fibroblasts. Immunofluorescence was utilized to assess the level of different myoepithelial and luminal markers at the cellular level. Flow cytometry allowed to determine the proportion of CD44- and ALDH1-positive breast fibroblasts, while sphere formation assay was used to test the ability of these cells to form mammospheres.

RESULTS

We have shown here that IL-6-dependent activation of breast and skin fibroblasts promotes mesenchymal-to-epithelial transition and stemness in a STAT3- and p16-dependent manner. Interestingly, most primary CAFs isolated from breast cancer patients exhibited such transition and expressed lower levels of the mesenchymal markers N-cadherin and vimentin as compared to their adjacent normal fibroblasts (TCFs) isolated from the same patients. We have also shown that some CAFs and IL-6-activated fibroblasts express high levels of the myoepithelial markers cytokeratin 14 and CD10. Interestingly, 12 CAFs isolated from breast tumors showed higher proportions of CD24^low/CD44^high and ALDH^high cells, compared to their corresponding TCF cells. These CD44^high cells have higher abilities to form mammospheres and to enhance cell proliferation of breast cancer cells in a paracrine manner relative to their corresponding CD44^low cells.

CONCLUSION

Together, the present findings show novel characteristics of active breast stromal fibroblasts, which exhibit additional myoepithelial/progenitor features.

Molecular mechanisms of tumor resistance to radiotherapy

BACKGROUND

Cancer is the most prevalent cause of death globally, and radiotherapy is considered the standard of care for most solid tumors, including lung, breast, esophageal, and colorectal cancers and glioblastoma. Resistance to radiation can lead to local treatment failure and even cancer recurrence.

MAIN BODY

In this review, we have extensively discussed several crucial aspects that cause resistance of cancer to radiation therapy, including radiation-induced DNA damage repair, cell cycle arrest, apoptosis escape, abundance of cancer stem cells, modification of cancer cells and their microenvironment, presence of exosomal and non-coding RNA, metabolic reprogramming, and ferroptosis. We aim to focus on the molecular mechanisms of cancer radiotherapy resistance in relation to these aspects and to discuss possible targets to improve treatment outcomes.

CONCLUSIONS

Studying the molecular mechanisms responsible for radiotherapy resistance and its interactions with the tumor environment will help improve cancer responses to radiotherapy. Our review provides a foundation to identify and overcome the obstacles to effective radiotherapy.

Tumor Microenvironment as a Therapeutic Target in Melanoma Treatment

The role of the tumor microenvironment in tumor growth and therapy has recently attracted more attention in research and drug development. The ability of the microenvironment to trigger tumor maintenance, progression, and resistance is the main cause for treatment failure and tumor relapse. Accumulated evidence indicates that the maintenance and progression of tumor cells is determined by components of the microenvironment, which include stromal cells (endothelial cells, fibroblasts, mesenchymal stem cells, and immune cells), extracellular matrix (ECM), and soluble molecules (chemokines, cytokines, growth factors, and extracellular vesicles). As a solid tumor, melanoma is not only a tumor mass of monolithic tumor cells, but it also contains supporting stroma, ECM, and soluble molecules. Melanoma cells are continuously in interaction with the components of the microenvironment. In the present review, we focus on the role of the tumor microenvironment components in the modulation of tumor progression and treatment resistance as well as the impact of the tumor microenvironment as a therapeutic target in melanoma.

Cellular and Molecular Players in the Tumor Microenvironment of Renal Cell Carcinoma

Globally, clear-cell renal cell carcinoma (ccRCC) represents the most prevalent type of kidney cancer. Surgery plays a key role in the treatment of this cancer, although one third of patients are diagnosed with metastatic ccRCC and about 25% of patients will develop a recurrence after nephrectomy with curative intent. Molecular-target-based agents, such as tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs), are recommended for advanced cancers. In addition to cancer cells, the tumor microenvironment (TME) includes non-malignant cell types embedded in an altered extracellular matrix (ECM). The evidence confirms that interactions among cancer cells and TME elements exist and are thought to play crucial roles in the development of cancer, making them promising therapeutic targets. In the TME, an unfavorable pH, waste product accumulation, and competition for nutrients between cancer and immune cells may be regarded as further possible mechanisms of immune escape. To enhance immunotherapies and reduce resistance, it is crucial first to understand how the immune cells work and interact with cancer and other cancer-associated cells in such a complex tumor microenvironment.

FAP, CD10, and GPR77-labeled CAFs cause neoadjuvant chemotherapy resistance by inducing EMT and CSC in gastric cancer

OBJECTIVE

A significant proportion of patients can not benefit from neoadjuvant chemotherapy (NCT) due to drug resistance. Cancer-associated fibroblasts (CAFs) influence many biological behaviours of tumors, including chemo-resistance. This study aims to explore whether CAFs expressing FAP, CD10, and GPR77 affect the efficacy of NCT and the prognosis of patients with gastric cancer, and its mechanism.

METHODS

One hundred seventy-one patients with locally progressive gastric adenocarcinoma who had undergone NCT and radical surgery were collected. Immunohistochemistry was used to detect the expression of FAP, CD10, and GPR77 in CAFs; the EMT markers (N-cadherin, Snail1, and Twist1) and the CSC markers (ALDH1, CD44, and LGR5) in gastric cancer cells. The χ² test was used to analyze the relationship between the expression of CAF, EMT, and CSC markers and the clinicopathological factors, as well as the relationship between CAF markers and EMT, and CSC markers. Logistic regression and Cox risk regression were used to analyze the relationship between the expression of CAF, EMT, and CSC markers and TRG grading and OS; Kaplan-Meier analysis was used for survival analysis and plotting the curves.

RESULTS

The expression of CAF markers FAP, CD10, and GPR77 was closely associated with that of EMT markers; FAP and CD10 were closely related to CSC markers. In the univariate analysis of pathological response, CAF markers (FAP, CD10, GPR77), EMT markers (N-cadherin, Snail1, Twist1), and CSC markers (ALDH1, LGR5, CD44), were all closely associated with pathological response (all p < 0.05). Only Twist1 was an independent factor affecting pathological response in multifactorial analysis (p = 0.001). In a univariate analysis of OS, expression of FAP and CD10 in CAF, as well as expression of EMT biomarkers (N-cadherin, Snail1), were significant factors influencing patient prognosis (all p < 0.05). Multifactorial analysis revealed N-cadherin (p = 0.032) and Snail1 (p = 0.028), as independent prognostic factors affecting OS.

CONCLUSION

FAP, CD10, and GPR77 labeled CAF subgroup may lead to NCT resistance and poor prognosis by inducing EMT and CSC of gastric cancer cells in locally advanced gastric cancer patients.

Uncovering the Secrets of Prostate Cancer's Radiotherapy Resistance: Advances in Mechanism Research

Prostate cancer (PCa) is a critical global public health issue with its incidence on the rise. Radiation therapy holds a primary role in PCa treatment; however, radiation resistance has become increasingly challenging as we uncover more about PCa's pathogenesis. Our review aims to investigate the multifaceted mechanisms underlying radiation therapy resistance in PCa. Specifically, we will examine how various factors, such as cell cycle regulation, DNA damage repair, hypoxic conditions, oxidative stress, testosterone levels, epithelial-mesenchymal transition, and tumor stem cells, contribute to radiation therapy resistance. By exploring these mechanisms, we hope to offer new insights and directions towards overcoming the challenges of radiation therapy resistance in PCa. This can also provide a theoretical basis for the clinical application of novel ultra-high-dose-rate (FLASH) radiotherapy in the era of PCa.

Heterogeneity and function of cancer-associated fibroblasts in renal cell carcinoma

With the advancement of anticancer therapy, there is increasing interest in understanding the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) play a pivotal role in the TME and have been the focus of much research in recent years. CAFs play an active role in cancer progression through complex interactions with other cells in the TME, releasing regulatory factors, synthesizing and remodeling the extracellular matrix. However, research on the role of CAFs in renal cell carcinoma (RCC) is still in its nascent stages. Here, we describe the origins and subgroups of CAFs, the roles of CAFs in the development and progression of RCC, the impact of CAFs on RCC prognosis, and the potential of CAFs as treatment targets in RCC. By analyzing CAF subsets, biomarkers, and targeted therapies, we present the significance and contribution of CAFs in RCC research. Furthermore, we highlight the distinct contribution of CAFs in advanced RCC through horizontal comparison with other cancers. This paper provides a comprehensive perspective of recent and foundational studies on the role of CAFs in RCC and other types of cancers and new insights for further study of CAFs in RCC.

Ferroptosis patterns modulate immunocyte communication in tumor microenvironments: clinical value and therapeutic guidance of lung adenocarcinoma

Lung adenocarcinoma (LUAD) emerges as one of the most aggressive tumor types with a poor prognosis. As a novel form of regulated cell death, ferroptosis promotes the clearance of tumor cells. However, few studies demonstrated whether ferroptosis-related genes can modify the behavior of tumor microenvironment (TME) cells. Resorting to non-negative matrix factorization (NMF) clustering based on the expression of ferroptosis-related genes, we identified multiple LUAD TME cell-type subpopulations. These subtypes of TME cells displayed extensive communication with tumor epithelial cells. ATF3+cancer-associated fibroblasts (CAFs), SLC40A1+CD8+T cells, and ALOX5+CD8+T cells showed distinct biological features compared to non-ferroptosis-related TME cells. Patients with a higher abundance of these ferroptosis-related TME cell subtypes showed a favorable clinical outcome. Our study depicted a detailed landscape of LUAD cell composition with a focus on ferroptosis-related genes, which, hopefully, may provide novel insight into further study of the LAUD immune microenvironment.

Cancer-associated fibroblasts and its derived exosomes: a new perspective for reshaping the tumor microenvironment

Cancer-associated fibroblasts (CAFs) are the most abundant stromal cells within the tumor microenvironment (TME). They extensively communicate with the other cells. Exosome-packed bioactive molecules derived from CAFs can reshape the TME by interacting with other cells and the extracellular matrix, which adds a new perspective for their clinical application in tumor targeted therapy. An in-depth understanding of the biological characteristics of CAF-derived exosomes (CDEs) is critical for depicting the detailed landscape of the TME and developing tailored therapeutic strategies for cancer treatment. In this review, we have summarized the functional roles of CAFs in the TME, particularly focusing on the extensive communication mediated by CDEs that contain biological molecules such as miRNAs, proteins, metabolites, and other components. In addition, we have also highlighted the prospects for diagnostic and therapeutic applications based on CDEs, which could guide the future development of exosome-targeted anti-tumor drugs.

Re-Shaping the Pancreatic Cancer Tumor Microenvironment: A New Role for the Metastasis Suppressor NDRG1

Pancreatic cancer (PaC) is a highly aggressive disease, with poor response to current treatments and 5-year survival rates of 10-15%. PaC progression is facilitated by its interaction with the complex and multifaceted tumor microenvironment (TME). In the TME, cancer cells and surrounding stromal cells constantly communicate with each other via the secretion and uptake of factors including cytokines, chemokines, growth factors, metabolites, and extracellular vesicles (EVs), reshaping the landscape of PaC. Recent studies demonstrated that the metastasis suppressor N-myc downstream regulated 1 (NDRG1) not only inhibits oncogenic signaling pathways in PaC cells but also alters the communication between PaC cells and the surrounding stroma. In fact, NDRG1 was found to influence the secretome of PaC cells, alter cancer cell metabolism, and interfere with intracellular trafficking and intercellular communication between PaC cells and surrounding fibroblasts. This review will present recent advancements in understanding the role of NDRG1 in PaC progression, with a focus on how this molecule influences PaC-stroma communication and its potential for re-shaping the PaC TME.

Dissecting the functions of cancer-associated fibroblasts to therapeutically target head and neck cancer microenvironment

Head and neck cancers (HNC) are a diverse group of aggressive malignancies with high morbidity and mortality, leading to almost half-million deaths annually worldwide. A better understanding of the molecular processes governing tumor formation and progression is crucial to improve current diagnostic and prognostic tools as well as to develop more personalized treatment strategies. Tumors are highly complex and heterogeneous structures in which growth and dissemination is not only governed by the cancer cells intrinsic mechanisms, but also by the surrounding tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) emerge as predominant TME components and key players in the generation of permissive conditions that ultimately impact in tumor progression and metastatic dissemination. Although CAFs were initially considered a consequence of tumor development, it is now well established that they actively contribute to numerous cancer hallmarks i.e., tumor cell growth, migration and invasion, cancer cell stemness, angiogenesis, metabolic reprograming, inflammation, and immune system modulation. In this scenario, therapeutic strategies targeting CAF functions could potentially have a major impact in cancer therapeutics, providing avenues for new treatment options or for improving efficacy in established approaches. This review is focused on thoroughly dissecting existing evidences supporting the contribution of CAFs in HNC biology with an emphasis on current knowledge of the key molecules and pathways involved in CAF-tumor crosstalk, and their potential as novel biomarkers and/or therapeutic targets to effectively interfere the tumor-stroma crosstalk for HNC patients benefit. involved in CAF-tumor crosstalk, and their potential as novel biomarkers and/or therapeutic targets to effec- tively interfere the tumor-stroma crosstalk for HNC patients benefit.

Metabolic-related gene signatures for survival prediction and immune cell subtypes associated with prognosis in intrahepatic cholangiocarcinoma

OBJECTIVES

Our study aimed to reveal the metabolic-related gene signatures for survival prediction and immune cell subtypes associated with IHCC prognosis.

METHODS

Differentially expressed metabolic genes were identified between survival group and dead group which were divided according to survival at discharge. Recursive feature elimination (RFE) and randomForest (RF) algorithms were applied to optimize the combination of feature metabolic genes, which were used to generate SVM classifier. Performance of SVM classifier was evaluated by receiver operating characteristic (ROC) curves. Gene set enrichment analysis (GSEA) was conducted to uncover the activated pathways in high risk group, and differences in immune cell distributions were revealed.

RESULTS

There were 143 differentially expressed metabolic gens. RFE and RF identified 21 overlapping differentially expressed metabolic genes, and the constructed SVM classifier had excellent accuracy in training and validation dataset. RS survival prediction model was consisted of 10 metabolic genes. RS model had reliable predictive capability in the training and validation dataset. GSEA revealed 15 significant KEGG pathways that were relatively activated in the high risk group. High risk group had obviously lower counts of B cell naive and T cell CD4+ memory resting, while higher counts of B cell plasma and macrophage M2.

CONCLUSION

Prognostic prediction model of 10 metabolic genes could accurately predict the prognosis of IHCC patients.

Fibroblasts in cancer: Unity in heterogeneity

Tumor cells do not exist in isolation in vivo, and carcinogenesis depends on the surrounding tumor microenvironment (TME), composed of a myriad of cell types and biophysical and biochemical components. Fibroblasts are integral in maintaining tissue homeostasis. However, even before a tumor develops, pro-tumorigenic fibroblasts in close proximity can provide the fertile 'soil' to the cancer 'seed' and are known as cancer-associated fibroblasts (CAFs). In response to intrinsic and extrinsic stressors, CAFs reorganize the TME enabling metastasis, therapeutic resistance, dormancy and reactivation by secreting cellular and acellular factors. In this review, we summarize the recent discoveries on CAF-mediated cancer progression with a particular focus on fibroblast heterogeneity and plasticity.

A novel inflammation-related signature for predicting prognosis and characterizing the tumor microenvironment in colorectal cancer

Inflammation is a critical component of tumor progression, and it modifies the tumor microenvironment by various mechanisms. Here, we explore the effect of the inflammatory response on the tumor microenvironment in colorectal cancer (CRC). A prognostic signature consisting of inflammation-related genes (IRGs) was constructed and verified based on the inflammatory response by bioinformatics analysis. IRG risk model was identified as an independent prognostic factor in CRC, and was related to biological processes of extracellular matrix, cell adhesion and angiogenesis. The IRG risk score predicted the clinical benefit of ipilimumab. Weighted correlation network analysis identified TIMP1 as the hub gene of the inflammatory response in the IRG risk model. Coculture experiments with macrophages and CRC cells revealed that TIMP1 promoted macrophage migration, inhibited the expression of M1 markers (CD11C and CD80), and promoted the expression of M2 markers (ARG1 and CD163). TIMP1 promoted the expression of ICAM1 and CCL2 by activating the ERK1/2 signaling pathway to promote macrophage migration and M2-like polarization. These IRGs in the risk model regulated stromal and immune components in the tumor microenvironment and could serve as potential therapeutic targets in CRC. TIMP1 promoted macrophage migration and meditated macrophage M2 polarization by activating ERK1/2/CLAM1 and CCL2.

SK2 channels set a signalling hub bolstering CAF-triggered tumourigenic processes in pancreatic cancer

OBJECTIVE

Intercellular communication within pancreatic ductal adenocarcinoma (PDAC) dramatically contributes to metastatic processes. The underlying mechanisms are poorly understood, resulting in a lack of targeted therapy to counteract stromal-induced cancer cell aggressiveness. Here, we investigated whether ion channels, which remain understudied in cancer biology, contribute to intercellular communication in PDAC.

DESIGN

We evaluated the effects of conditioned media from patient-derived cancer-associated fibroblasts (CAFs) on electrical features of pancreatic cancer cells (PCC). The molecular mechanisms were deciphered using a combination of electrophysiology, bioinformatics, molecular and biochemistry techniques in cell lines and human samples. An orthotropic mouse model where CAF and PCC were co-injected was used to evaluate tumour growth and metastasis dissemination. Pharmacological studies were carried out in the Pdx1-Cre, Ink4a^fl/fl LSL-Kras^G12D (KIC^pdx1) mouse model.

RESULTS

We report that the K⁺ channel SK2 expressed in PCC is stimulated by CAF-secreted cues (8.84 vs 2.49 pA/pF) promoting the phosphorylation of the channel through an integrin-epidermal growth factor receptor (EGFR)-AKT (Protein kinase B) axis. SK2 stimulation sets a positive feedback on the signalling pathway, increasing invasiveness in vitro (threefold) and metastasis formation in vivo. The CAF-dependent formation of the signalling hub associating SK2 and AKT requires the sigma-1 receptor chaperone. The pharmacological targeting of Sig-1R abolished CAF-induced activation of SK2, reduced tumour progression and extended the overall survival in mice (11.7 weeks vs 9.5 weeks).

CONCLUSION

We establish a new paradigm in which an ion channel shifts the activation level of a signalling pathway in response to stromal cues, opening a new therapeutic window targeting the formation of ion channel-dependent signalling hubs.

Fibroblasts as Turned Agents in Cancer Progression

Differentiated epithelial cells reside in the homeostatic microenvironment of the native organ stroma. The stroma supports their normal function, their G0 differentiated state, and their expansion/contraction through the various stages of the life cycle and physiologic functions of the host. When malignant transformation begins, the microenvironment tries to suppress and eliminate the transformed cells, while cancer cells, in turn, try to resist these suppressive efforts. The tumor microenvironment encompasses a large variety of cell types recruited by the tumor to perform different functions, among which fibroblasts are the most abundant. The dynamics of the mutual relationship change as the sides undertake an epic battle for control of the other. In the process, the cancer "wounds" the microenvironment through a variety of mechanisms and attracts distant mesenchymal stem cells to change their function from one attempting to suppress the cancer, to one that supports its growth, survival, and metastasis. Analogous reciprocal interactions occur as well between disseminated cancer cells and the metastatic microenvironment, where the microenvironment attempts to eliminate cancer cells or suppress their proliferation. However, the altered microenvironmental cells acquire novel characteristics that support malignant progression. Investigations have attempted to use these traits as targets of novel therapeutic approaches.

Epithelial-mesenchymal transition-related gene prognostic index and phenotyping clusters for hepatocellular carcinoma patients

Epithelial-mesenchymal transition (EMT) contributes to high tumor heterogeneity and the immunosuppressive environment of the HCC tumor microenvironment (TME). Here, we developed EMT-related genes phenotyping clusters and systematically evaluated their impact on HCC prognosis, the TME, and drug efficacy prediction. We identified HCC specific EMT-related genes using weighted gene co-expression network analysis (WGCNA). An EMT-related genes prognostic index (EMT-RGPI) capable of effectively predicting HCC prognosis was then constructed. Consensus clustering of 12 HCC specific EMT-related hub genes uncovered two molecular clusters C1 and C2. Cluster C2 preferentially associated with unfavorable prognosis, higher stemness index (mRNAsi) value, elevated immune checkpoint expression, and immune cell infiltration. The TGF-β signaling, EMT, glycolysis, Wnt β-catenin signaling, and angiogenesis were markedly enriched in cluster C2. Moreover, cluster C2 exhibited higher TP53 and RB1 mutation rates. The TME subtypes and tumor immune dysfunction and exclusion (TIDE) score showed that cluster C1 patients responded well to immune checkpoint inhibitors (ICIs). Half-maximal inhibitory concentration (IC50) revealed that cluster C2 patients were more sensitive to chemotherapeutic and antiangiogenic agents. These findings may guide risk stratification and precision therapy for HCC patients.

High Expression Level of BRD4 Is Associated with a Poor Prognosis and Immune Infiltration in Esophageal Squamous Cell Carcinoma

BACKGROUND

Bromodomain-containing protein 4 (BRD4) is a reader of histone acetylation and is associated with a variety of diseases.

AIM

To investigate the expression level of BRD4 in esophageal squamous cell carcinoma (ESCC), its prognostic value and its relationship with immune infiltration.

METHODS

The study included 94 ESCC patients from The Cancer Genome Atlas (TCGA) database and 179 ESCC patients from Affiliated Hospital 2 of Nantong University. The expression levels of proteins in tissue microarray were detected by immunohistochemistry. The prognostic factors were analyzed by Kaplan-Meier curve and univariate and multivariate cox regression. The ESTIMATE website was used to calculate the stromal, immune and ESTIMATE score. CIBERSORT was used to calculate the abundance of immune infiltrates. Spearman and Phi coefficient were used for correlation analysis. The TIDE algorithm was used to predict treatment response to immune checkpoint blockade.

RESULTS

BRD4 is up-regulated in ESCC, and high BRD4 expression level is associated with poor prognosis and adverse clinicopathological features. In addition, the monocyte count, systemic inflammatory-immunologic index, platelet-lymphocyte ratio, and monocyte-lymphocyte ratio in the BRD4 high expression level group were higher than in the low expression level group. Finally, we found that BRD4 expression level correlated with immune infiltration and that it was inversely correlated with infiltration of CD8 + T cells. Higher TIDE scores in the BRD4 high expression group than in the low expression group.

CONCLUSION

BRD4 is associated with poor prognosis and immune infiltration in ESCC, and may be a potential biomarker for prognosis and immunotherapy application.

MUG CCArly: A Novel Autologous 3D Cholangiocarcinoma Model Presents an Increased Angiogenic Potential

Cholangiocarcinoma (CCA) are characterized by their desmoplastic and hypervascularized tumor microenvironment (TME), which is mainly composed of tumor cells and cancer-associated fibroblasts (CAFs). CAFs play a pivotal role in general and CCA tumor progression, angiogenesis, metastasis, and the development of treatment resistance. To our knowledge, no continuous human in vivo-like co-culture model is available for research. Therefore, we aimed to establish a new model system (called MUG CCArly) that mimics the desmoplastic microenvironment typically seen in CCA. Proteomic data comparing the new CCA tumor cell line with our co-culture tumor model (CCTM) indicated a higher gene expression correlation of the CCTM with physiological CCA characteristics. A pro-angiogenic TME that is typically observed in CCA could also be better simulated in the CCTM group. Further analysis of secreted proteins revealed CAFs to be the main source of these angiogenic factors. Our CCTM MUG CCArly represents a new, reproducible, and easy-to-handle 3D CCA model for preclinical studies focusing on CCA-stromal crosstalk, tumor angiogenesis, and invasion, as well as the immunosuppressive microenvironment and the involvement of CAFs in the way that drug resistance develops.

Cancer-associated fibroblast-derived secreted phosphoprotein 1 contributes to resistance of hepatocellular carcinoma to sorafenib and lenvatinib

BACKGROUND

Cancer-associated fibroblasts (CAFs) play an important role in the induction of chemo-resistance. This study aimed to clarify the mechanism underlying CAF-mediated resistance to two tyrosine kinase inhibitors (TKIs), sorafenib and lenvatinib, and to identify a novel therapeutic target for overcoming TKI resistance in hepatocellular carcinoma (HCC).

METHODS

We performed a systematic integrative analysis of publicly available gene expression datasets and whole-transcriptome sequencing data from 9 pairs of CAFs and para-cancer fibroblasts isolated from human HCC and para-tumor tissues, respectively, to identify key molecules that might induce resistance to TKIs. We then performed in vitro and in vivo experiments to validate selected targets and related mechanisms. The associations of plasma secreted phosphoprotein 1 (SPP1) expression levels before sorafenib/lenvatinib treatment with progression-free survival (PFS) and overall survival (OS) of 54 patients with advanced HCC were evaluated using Kaplan-Meier and Cox regression analysis.

RESULTS

Bioinformatic analysis identified CAF-derived SPP1 as a candidate molecule driving TKI resistance. SPP1 inhibitors reversed CAF-induced TKI resistance in vitro and in vivo. CAF-derived SPP1 activated rapidly accelerated fibrosarcoma (RAF)/mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) through the integrin-protein kinase C-alpha (PKCα) signaling pathway and promoted epithelial-to-mesenchymal transition (EMT). A high plasma SPP1 level before TKI treatment was identified as an independent predictor of poor PFS (P = 0.026) and OS (P = 0.047) in patients with advanced HCC after TKI treatment.

CONCLUSIONS

CAF-derived SPP1 enhances TKI resistance in HCC via bypass activation of oncogenic signals and EMT promotion. Its inhibition represents a promising therapeutic strategy against TKI resistance in HCC. Moreover, plasma SPP1 level before TKI treatment represents a potential biomarker for treatment response prediction.

The Role of Different Immunocompetent Cell Populations in the Pathogenesis of Head and Neck Cancer-Regulatory Mechanisms of Pro- and Anti-Cancer Activity and Their Impact on Immunotherapy

Head and neck squamous cell carcinoma (HNSCC) is one of the most aggressive and heterogeneous groups of human neoplasms. HNSCC is characterized by high morbidity, accounting for 3% of all cancers, and high mortality with ~1.5% of all cancer deaths. It was the most common cancer worldwide in 2020, according to the latest GLOBOCAN data, representing the seventh most prevalent human malignancy. Despite great advances in surgical techniques and the application of modern combinations and cytotoxic therapies, HNSCC remains a leading cause of death worldwide with a low overall survival rate not exceeding 40-60% of the patient population. The most common causes of death in patients are its frequent nodal metastases and local neoplastic recurrences, as well as the relatively low response to treatment and severe drug resistance. Much evidence suggests that the tumour microenvironment (TME), tumour infiltrating lymphocytes (TILs) and circulating various subpopulations of immunocompetent cells, such regulatory T cells (CD4+CD25+Foxp3+Tregs), cytotoxic CD3+CD8+ T cells (CTLs) and CD3+CD4+ T helper type 1/2/9/17 (Th1/Th2/Th9/Th17) lymphocytes, T follicular helper cells (Tfh) and CD56dim/CD16bright activated natural killer cells (NK), carcinoma-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), tumour-associated neutrophils (N1/N2 TANs), as well as tumour-associated macrophages (M1/M2 phenotype TAMs) can affect initiation, progression and spread of HNSCC and determine the response to immunotherapy. Rapid advances in the field of immuno-oncology and the constantly growing knowledge of the immunosuppressive mechanisms and effects of tumour cancer have allowed for the use of effective and personalized immunotherapy as a first-line therapeutic procedure or an essential component of a combination therapy for primary, relapsed and metastatic HNSCC. This review presents the latest reports and molecular studies regarding the anti-tumour role of selected subpopulations of immunocompetent cells in the pathogenesis of HNSCC, including HPV+ve (HPV+) and HPV-ve (HPV-) tumours. The article focuses on the crucial regulatory mechanisms of pro- and anti-tumour activity, key genetic or epigenetic changes that favour tumour immune escape, and the strategies that the tumour employs to avoid recognition by immunocompetent cells, as well as resistance mechanisms to T and NK cell-based immunotherapy in HNSCC. The present review also provides an overview of the pre- and clinical early trials (I/II phase) and phase-III clinical trials published in this arena, which highlight the unprecedented effectiveness and limitations of immunotherapy in HNSCC, and the emerging issues facing the field of HNSCC immuno-oncology.

Assessing the epithelial-to-mesenchymal plasticity in a small cell lung carcinoma (SCLC) and lung fibroblasts co-culture model

The tumor microenvironment (TME) is the source of important cues that govern epithelial-to-mesenchymal transition (EMT) and facilitate the acquisition of aggressive traits by cancer cells. It is now recognized that EMT is not a binary program, and cancer cells rarely switch to a fully mesenchymal phenotype. Rather, cancer cells exist in multiple hybrid epithelial/mesenchymal (E/M) states responsible for cell population heterogeneity, which is advantageous for the ever-changing environment during tumor development and metastasis. How are these intermediate states generated and maintained is not fully understood. Here, we show that direct interaction between small cell lung carcinoma cells and lung fibroblasts induces a hybrid EMT phenotype in cancer cells in which several mesenchymal genes involved in receptor interaction with the extracellular matrix (ECM) and ECM remodeling are upregulated while epithelial genes such as E-cadherin remain unchanged or slightly increase. We also demonstrate that several core EMT-regulating transcription factors (EMT-TFs) are upregulated in cancer cells during direct contact with fibroblasts, as is Yes-associated protein (YAP1), a major regulator of the Hippo pathway. Further, we show that these changes are transient and reverse to the initial state once the interaction is disrupted. Altogether, our results provide evidence that tumor cells' direct contact with the fibroblasts in the TME initiates a signaling cascade responsible for hybrid E/M states of cancer cells. These hybrid states are maintained during the interaction and possibly contribute to therapy resistance and immune evasion, while interference with direct contact will result in slow recovery and switch to the initial states.

Cancer associated fibroblast derived gene signature determines cancer subtypes and prognostic model construction in head and neck squamous cell carcinomas

BACKGROUND

Head and neck squamous cell carcinomas (HNSCC) are the most common type of head and neck cancer with an unimproved prognosis over the past decades. Although the role of cancer-associated-fibroblast (CAF) has been demonstrated in HNSCC, the correlation between CAF-derived gene expression and patient prognosis remains unknown.

METHODS

A total of 528 patients from TCGA database and 270 patients from GSE65858 database were contained in this study. After extracting 66 CAF-related gene expression data from TCGA database, consensus clustering was performed to identify different HNSCC subtypes. Limma package was used to distinguish the differentially expression genes (DEGs) between these subtypes, followed by Lasso regression analysis to construct a prognostic model. The model was validated by performing Kaplan-Meier survival, ROC and risk curve, univariate and multivariate COX regression analysis. GO, KEGG, GSEA, ESTIMATE and ssGSEA analyses was performed to explort the potential mechanism leading to different prognosis.

RESULTS

Based on the 66 CAF-related gene expression pattern we stratitied HNSCC patients into two previously unreported subtypes with different clinical outcomes. A prognostic model composed of 15 DEGs was constructed and validated. In addition, bioinformatics analysis showed that the prognostic risk of HNSCC patients was also negatively correlated to immune infiltration, implying the role of tumor immune escape in HNSCC prognosis and treatment option.

CONCLUSIONS

The study develops a reliable prognostic prediction tool and provides a theoretical treatment guidance for HNSCC patients.

Single-cell transcriptomic analysis deciphers key transitional signatures associated with oncogenic evolution in human intramucosal oesophageal squamous cell carcinoma

BACKGROUND AND AIMS

The early diagnosis and intervention of oesophageal squamous cell carcinoma (ESCC) are particularly important because of the lack of effective therapies and poor prognosis. Comprehensive research on early ESCC at the single-cell level is rare due to the need for fresh and high-quality specimens obtained from ESD. This study aims to systematically describe the cellular atlas of human intramucosal ESCC.

METHODS

Five paired samples of intramucosal ESCC, para-ESCC oesophageal tissues from endoscopically resected specimens and peripheral blood mononuclear cells were adopted for scRNA-seq analysis. Computational pipeline scMetabolism was applied to quantify the metabolic diversity of single cells.

RESULTS

A total of 164 715 cells were profiled. Epithelial cells exhibited high intra-tumoural heterogeneity and two evolutionary trajectories during ESCC tumorigenesis initiated from proliferative cells, and then through an intermediate state, to two different terminal states of normally differentiated epithelial cells or malignant cells, respectively. The abundance of CD8+ TEX s, Tregs and PD1+ CD4+ T cells suggested an exhausted and suppressive immune microenvironment. Several genes in immune cells, such as CXCL13, CXCR5 and PADI4, were identified as new biomarkers for poor prognosis. A new subcluster of malignant cells associated with metastasis and angiogenesis that appeared at an early stage compared with progressive ESCC was also identified in this study. Intercellular interaction analysis based on ligand-receptor pairs revealed the subcluster of malignant cells interacting with CAFs via the MDK-NCL pathway, which was verified by cell proliferation assay and IHC. This indicates that the interaction may be an important hallmark in the early change of tumour microenvironment and serves as a sign of CAF activation to stimulate downstream pathways for facilitating tumour invasion.

CONCLUSION

This study demonstrates the changes of cell subsets and transcriptional levels in human intramucosal ESCC, which may provide unique insights into the development of novel biomarkers and potential intervention strategies.

Beyond direct killing-novel cellular immunotherapeutic strategies to reshape the tumor microenvironment

The clinical use of cellular immunotherapies is gaining momentum and the number of approved indications is steadily increasing. One class of cellular therapies-chimeric antigen receptor (CAR)-modified T cells-has achieved impressive results in distinct blood cancer indications. These existing cellular therapies treating blood cancers face significant relapse rates, and their application beyond hematology has been underwhelming, especially in solid oncology. Major reasons for resistance source largely in the tumor microenvironment (TME). The TME in fact functionally suppresses, restricts, and excludes adoptive immune cells, which limits the efficacy of cellular immunotherapies from the onset. Many promising efforts are ongoing to adapt cellular immunotherapies to address these obstacles, with the aim of reshaping the tumor microenvironment to ameliorate function and to achieve superior efficacy against both hematological and solid malignancies.

Cancer-associated fibroblasts: Versatile mediators in remodeling the tumor microenvironment

Current cancer therapeutic strategies are generally not sufficient to eradicate malignancy, as cancer stroma cells contribute to tumor evasion and therapeutic resistance. Cancer-associated fibroblasts (CAFs) constitute a largely heterogeneous type of stromal cell population and are important components of the tumor microenvironment (TME). CAFs are the most abundant stromal cell type and are actively involved in tumor progression through complex mechanisms involving effects on other cell types. Research conducted in recent years has emphasized an emerging function of CAFs in the remodeling of the TME that promotes tumor progression with effects on response to treatment by various molecular mechanisms. A comprehensive mechanism of tumor-promoting activities of CAFs could facilitate the development of novel diagnostic and therapeutic approaches. In this review, the biological characterization of CAFs and the mechanisms of their effects on TME remodeling are summarized. Furthermore, we also highlight currently available therapeutic strategies targeting CAF in the context of optimizing the success of immunotherapies and briefly discuss possible future perspectives and challenges related to CAF studies.

Harnessing epithelial-mesenchymal plasticity to boost cancer immunotherapy

Immune checkpoint blockade (ICB) therapy is a powerful option for cancer treatment. Despite demonstrable progress, most patients fail to respond or achieve durable responses due to primary or acquired ICB resistance. Recently, tumor epithelial-to-mesenchymal plasticity (EMP) was identified as a critical determinant in regulating immune escape and immunotherapy resistance in cancer. In this review, we summarize the emerging role of tumor EMP in ICB resistance and the tumor-intrinsic or extrinsic mechanisms by which tumors exploit EMP to achieve immunosuppression and immune escape. We discuss strategies to modulate tumor EMP to alleviate immune resistance and to enhance the efficiency of ICB therapy. Our discussion provides new prospects to enhance the ICB response for therapeutic gain in cancer patients.

Role of tumor microenvironment in cancer progression and therapeutic strategy

Cancer is now considered a tumor microenvironment (TME) disease, although it was originally thought to be a cell and gene expression disorder. Over the past 20 years, significant advances have been made in understanding the complexity of the TME and its impact on responses to various anticancer therapies, including immunotherapies. Cancer immunotherapy can recognize and kill cancer cells by regulating the body's immune system. It has achieved good therapeutic effects in various solid tumors and hematological malignancies. Recently, blocking of programmed death-1 (PD-1), programmed death-1 ligand-1 (PD-L1), and programmed death Ligand-2 (PD-L2), the construction of antigen chimeric T cells (CAR-T) and tumor vaccines have become popular immunotherapies Tumorigenesis, progression, and metastasis are closely related to TME. Therefore, we review the characteristics of various cells and molecules in the TME, the interaction between PD-1 and TME, and promising cancer immunotherapy therapeutics.

Liquid biopsy at the frontier in renal cell carcinoma: recent analysis of techniques and clinical application

Renal cell carcinoma (RCC) is a major pathological type of kidney cancer and is one of the most common malignancies worldwide. The unremarkable symptoms of early stages, proneness to postoperative metastasis or recurrence, and low sensitivity to radiotherapy and chemotherapy pose a challenge for the diagnosis and treatment of RCC. Liquid biopsy is an emerging test that measures patient biomarkers, including circulating tumor cells, cell-free DNA/cell-free tumor DNA, cell-free RNA, exosomes, and tumor-derived metabolites and proteins. Owing to its non-invasiveness, liquid biopsy enables continuous and real-time collection of patient information for diagnosis, prognostic assessment, treatment monitoring, and response evaluation. Therefore, the selection of appropriate biomarkers for liquid biopsy is crucial for identifying high-risk patients, developing personalized therapeutic plans, and practicing precision medicine. In recent years, owing to the rapid development and iteration of extraction and analysis technologies, liquid biopsy has emerged as a low cost, high efficiency, and high accuracy clinical detection method. Here, we comprehensively review liquid biopsy components and their clinical applications over the past 5 years. Additionally, we discuss its limitations and predict its future prospects.

DZIP1 expressed in fibroblasts and tumor cells may affect immunosuppression and metastatic potential in gastric cancer

The tumor microenvironment (TME) contains complex components, of which the most well-known one is the tumor-associated fibroblast (CAF) that participates in the development and progression of tumors. A high abundance of CAFs implies that tumor stroma is also abundant and often predicts a poor prognosis, especially in terms of immunotherapeutic resistance. In this study, DAZ interacting zinc finger protein 1 (DZIP1) was identified to be upregulated in CAFs and malignant epithelial cells based on single-cell sequencing. Furthermore, results from The Cancer Genome Atlas database showed that this gene was highly positively associated with the mesenchymal phenotype in gastric cancer (GC). In addition, molecular experiments verified that DZIP1 directly promoted the proliferation of CAFs and enhanced the epithelial-mesenchymal transition (EMT) of GC cells to drive angiogenesis. Also, the upregulated DZIP1 in GC cells was found to directly promote invasion and metastasis. Finally, multiplex immunofluorescence and immunohistochemistry showed that DZIP1 was correlated with the immunosuppressive microenvironment of GC and resulted in a poor response to immunotherapy. Overall, our findings suggest that DZIP1 is expressed in both tumor parenchyma and mesenchyme and that it is involved in shaping the immunosuppressive microenvironment and inducing EMT by participating in tumor-stromal signaling crosstalk.

The role of fatty acid desaturase 2 in multiple tumor types revealed by bulk and single-cell transcriptomes

BACKGROUND

Previous studies have demonstrated the important role of fatty acid desaturase 2 (FADS2) in governing tumorigenesis and tumor metastasis. Although FADS2 is an essential regulator of fatty acid metabolism, its prognostic and immunotherapeutic value remains uncertain.

METHODS

The role of FADS2 was investigated across different types of tumors. Besides, the relationship between FADS2 and survival prognosis, clinicopathologic features, tumor-infiltrating immune cells, immunoregulatory genes, chemokines, chemokines receptor, tumor mutational burden (TMB), and microsatellite instability (MSI) was also explored. FADS2-related genes enrichment analysis was performed to further explore the molecular function of FADS2. Finally, the relationship between FADS2 expression and altered functional states in single-cell levels across different tumor cells was explored.

RESULTS

FADS2 was increased in most tumor tissues. Elevated FADS2 expression was associated with a poor overall survival (OS) and disease-free survival (DFS). FADS2 amplification was germane to worse progress-free survival (PFS). In addition, FADS2 correlated with the majority of tumor-infiltrating immune cells, immunoregulatory genes, and chemokines. Especially, FADS2 expression positively correlated with cancer-associated fibroblast (CAFs) infiltration. Gene Ontology and KEGG analysis demonstrated that FADS2 was involved in the fatty acid metabolic process, arachidonic acid metabolism, RAS, PPAR, and VEGF pathway. FADS2 had a positive relationship with tumor biological behaviors such as inflammation, cell cycle, proliferation, DNA damage, and DNA repair response in single-cell levels.

CONCLUSIONS

FADS2 can serve as a potential prognostic and immunotherapeutic biomarker for multiple tumors, revealing new insights and evidence for cancer treatment.

Different Expression and Clinical Implications of Cancer-Associated Fibroblast (CAF) Markers in Brain Metastases

Aims: This study assessed the expression and clinical relevance of cancer-asssociated fibroblast (CAF)-related biomarkers in brain metastasis (BM). Moreover, molecular characterization of patient-derived primary CAFs and normal fibroblasts (NFs) was performed. Methods: Sixty-eight patients with BM from various primary cancer types were selected. Immunohistochemistry (IHC) and immunofluorescence (IF) staining were performed to evaluate the expression of various CAF-related biomarkers. CAFs and NFs were isolated from fresh tissues. Results: Various CAF-related biomarkers were expressed in CAFs in BMs of different primary cancers. However, only PDGFR-β, α-SMA, and collagen type I were associated with BM size. PDGFR-β and α-SMA were associated with BM recurrence after resection. PDGFR-β was associated with recurrence-free survival (RFS). Interestingly, high expression of PDGFR-β and α-SMA was found in the patients with previous chemotherapy or radiotherapy for primary cancer. In primary cell culture, PDGFR-β and α-SMA were expressed at higher levels in patient-derived CAFs than in NFs or cancer cells. The origins of CAF in BM were presumed to be pericytes of blood vessels, circulating endothelial progenitor cells, or transformed astrocytes of the peritumoral glial stroma. Conclusion: Our results suggest that high expression of CAF-related biomarkers, particularly PDGFR-β and α-SMA, is associated with poor prognosis and recurrence in patients with BM. With the elucidation of the role and origins of CAF in the tumor microenvironment, CAF can be a new imperative target for BM immunotherapy.

Cancer-associated fibroblasts: The chief architect in the tumor microenvironment

Stromal heterogeneity of tumor microenvironment (TME) plays a crucial role in malignancy and therapeutic resistance. Cancer-associated fibroblasts (CAFs) are one of the major players in tumor stroma. The heterogeneous sources of origin and subsequent impacts of crosstalk with breast cancer cells flaunt serious challenges before current therapies to cure triple-negative breast cancer (TNBC) and other cancers. The positive and reciprocal feedback of CAFs to induce cancer cells dictates their mutual synergy in establishing malignancy. Their substantial role in creating a tumor-promoting niche has reduced the efficacy of several anti-cancer treatments, including radiation, chemotherapy, immunotherapy, and endocrine therapy. Over the years, there has been an emphasis on understanding CAF-induced therapeutic resistance in order to enhance cancer therapy results. CAFs, in the majority of cases, employ crosstalk, stromal management, and other strategies to generate resilience in surrounding tumor cells. This emphasizes the significance of developing novel strategies that target particular tumor-promoting CAF subpopulations, which will improve treatment sensitivity and impede tumor growth. In this review, we discuss the current understanding of the origin and heterogeneity of CAFs, their role in tumor progression, and altering the tumor response to therapeutic agents in breast cancer. In addition, we also discuss the potential and possible approaches for CAF-mediated therapies.

Combination, Modulation and Interplay of Modern Radiotherapy with the Tumor Microenvironment and Targeted Therapies in Pancreatic Cancer: Which Candidates to Boost Radiotherapy?

Pancreatic ductal adenocarcinoma cancer (PDAC) is a highly diverse disease with low tumor immunogenicity. PDAC is also one of the deadliest solid tumor and will remain a common cause of cancer death in the future. Treatment options are limited, and tumors frequently develop resistance to current treatment modalities. Since PDAC patients do not respond well to immune checkpoint inhibitors (ICIs), novel methods for overcoming resistance are being explored. Compared to other solid tumors, the PDAC's tumor microenvironment (TME) is unique and complex and prevents systemic agents from effectively penetrating and killing tumor cells. Radiotherapy (RT) has the potential to modulate the TME (e.g., by exposing tumor-specific antigens, recruiting, and infiltrating immune cells) and, therefore, enhance the effectiveness of targeted systemic therapies. Interestingly, combining ICI with RT and/or chemotherapy has yielded promising preclinical results which were not successful when translated into clinical trials. In this context, current standards of care need to be challenged and transformed with modern treatment techniques and novel therapeutic combinations. One way to reconcile these findings is to abandon the concept that the TME is a well-compartmented population with spatial, temporal, physical, and chemical elements acting independently. This review will focus on the most interesting advancements of RT and describe the main components of the TME and their known modulation after RT in PDAC. Furthermore, we will provide a summary of current clinical data for combinations of RT/targeted therapy (tRT) and give an overview of the most promising future directions.