Functional diversity of cancer-associated fibroblasts in modulating drug resistance

Development and validation of a cancer-associated fibroblast gene signature-based model for predicting immunotherapy response in colon cancer

The efficacy of immune checkpoint inhibitors in colon cancer has been established, and there is an urgent need to identify new molecular markers for colon cancer immunotherapy to guide clinical decisions. Using the "EPIC" and "MCPcounter" R packages to conduct cancer-associated fibroblast (CAF) infiltration scoring on colon cancer samples from the TCGA database and the GEO database, the WGCNA analysis was performed on the two databases' samples based on the CAF infiltration scores to screen for CAF-related genes. LASSO regression analysis was used to construct a risk model with these genes. Comprehensive bioinformatics analysis was conducted on the constructed model to evaluate the stability of its prediction of CAF infiltration abundance and the stability of its prediction of immunotherapy efficacy. The newly constructed risk model could well reflect the abundance of CAF infiltration in colon cancer, with a correlation coefficient of 0.91 in the training cohort TCGA-COAD and 0.88 in the validation cohort GSE39582. GSEA analysis revealed that CAF is closely related to functions associated with extracellular matrix remodeling. The constructed risk model can predict the efficacy of immunotherapy in colon cancer well, with the high-risk group showing significantly poorer immunotherapy response than the low-risk group, with an expected effective rate of immunotherapy of 68 vs. 24% in the training group (P < 0.001) and 64 vs. 26% in the validation group (P < 0.001). The AUC value for predicting immunotherapy response by the risk model in the training group was 0.780 (95% CI 0.736-0.820), and in the validation group, the AUC value was 0.774 (95% CI 0.735-0.810). Drug sensitivity analysis showed that the expected chemotherapeutic effect in the low-risk group was superior to that in the high-risk group. CAF is associated with immunosuppression and drug resistance. Predicting the efficacy of immunotherapy in colon cancer based on the abundance of CAF infiltration is a feasible approach. For the high-risk population identified by our model, clinical consideration should be given to prioritizing non-immunotherapy approaches to avoid potential risks associated with immunotherapy.

Deciphering the landscape of triple negative breast cancer from microenvironment dynamics and molecular insights to biomarker analysis and therapeutic modalities

Triple negative breast cancer (TNBC) displays a notable challenge in clinical oncology due to its invasive nature which is attributed to the absence of progesterone receptor (PR), estrogen receptor (ER), and human epidermal growth factor receptor (HER-2). The heterogenous tumor microenvironment (TME) of TNBC is composed of diverse constituents that intricately interact to evade immune response and facilitate cancer progression and metastasis. Based on molecular gene expression, TNBC is classified into four molecular subtypes: basal-like (BL1 and BL2), luminal androgen receptor (LAR), immunomodulatory (IM), and mesenchymal. TNBC is an aggressive histological variant with adverse prognosis and poor therapeutic response. The lack of response in most of the TNBC patients could be attributed to the heterogeneity of the disease, highlighting the need for more effective treatments and reliable prognostic biomarkers. Targeting certain signaling pathways and their components has emerged as a promising therapeutic strategy for improving patient outcomes. In this review, we have summarized the interactions among various components of the dynamic TME in TNBC and discussed the classification of its molecular subtypes. Moreover, the purpose of this review is to compile and provide an overview of the most recent data about recently discovered novel TNBC biomarkers and targeted therapeutics that have proven successful in treating metastatic TNBC. The emergence of novel therapeutic strategies such as chemoimmunotherapy, chimeric antigen receptor (CAR)-T cells-based immunotherapy, phytometabolites-mediated natural therapy, photodynamic and photothermal approaches have made a significant positive impact and have paved the way for more effective interventions.

The genetic architecture of bone metastases: unveiling the role of epigenetic and genetic modifications in drug resistance

Bone metastases represent frequent and severe complications in various cancers, notably impacting prognosis and quality of life. This review article delves into the genetic and epigenetic mechanisms underpinning drug resistance in bone metastases, a key challenge in effective cancer treatment. The development of drug resistance in cancer can manifest as either intrinsic or acquired, with genetic heterogeneity playing a pivotal role. Intrinsic resistance is often due to pre-existing mutations, while acquired resistance evolves through genetic and epigenetic alterations during treatment. These alterations include mutations in driver genes like TP53 and RB1, epigenetic modifications such as DNA methylation and histone changes, and pathway alterations, notably involving RANK-RANKL signaling and the PI3K/AKT/mTOR cascade. Recent studies underline the significance of the tumor microenvironment in fostering drug resistance, with components such as cancer-associated fibroblasts and hypoxia playing crucial roles. The interactions between metastatic cancer cells and the bone microenvironment facilitate survival and the proliferation of drug-resistant clones. This review highlights the necessity of understanding these complex interactions to develop targeted therapies that can overcome resistance and improve treatment outcomes. Current therapeutic strategies and future directions are discussed, emphasizing the integration of genomic profiling and targeted interventions in managing bone metastases. The evolving landscape of genetic research, including the application of next-generation sequencing and CRISPR technology, offers promising avenues for novel and more effective therapeutic strategies. This comprehensive exploration aims to provide insights into the molecular intricacies of drug resistance in bone metastases, paving the way for improved clinical management and patient care.

Current Understanding of Therapeutic and Diagnostic Applications of Exosomes in Pancreatic Cancer

ABSTRACT

Unusual symptoms, rapid progression, lack of reliable early diagnostic biomarkers, and lack of efficient treatment choices are the ongoing challenges of pancreatic cancer. Numerous research studies have demonstrated the correlation between exosomes and various aspects of pancreatic cancer. In light of these facts, exosomes possess the potential to play functional roles in the treatment, prognosis, and diagnosis of the pancreatic cancer. In the present study, we reviewed the most recent developments in approaches for exosome separation, modification, monitoring, and communication. Moreover, we discussed the clinical uses of exosomes as less invasive liquid biopsies and drug carriers and their contribution to the control of angiogenic activity of pancreatic cancer. Better investigation of exosome biology would help to effectively engineer therapeutic exosomes with certain nucleic acids, proteins, and even exogenous drugs as their cargo. Circulating exosomes have shown promise as reliable candidates for pancreatic cancer early diagnosis and monitoring in high-risk people without clinical cancer manifestation. Although we have tried to reflect the status of exosome applications in the treatment and detection of pancreatic cancer, it is evident that further studies and clinical trials are required before exosomes may be employed as a routine therapeutic and diagnostic tools for pancreatic cancer.

Targeting Cancer-Associated Fibroblasts: Eliminate or Reprogram?

Cancer-associated fibroblasts (CAFs) are key components of the tumor microenvironment (TME). Given their various roles in tumor progression and treatment resistance, CAFs are promising therapeutic targets in cancer. The elimination of tumor-promoting CAFs has been investigated in various animal models to determine whether it effectively suppresses tumor growth. Based on recent evidence, several simple strategies have been proposed to eliminate tumor-promoting CAFs and attenuate these features. In addition, attention has focused on the critical role that CAFs play in the immunosuppressive TME. Therefore, the functional reprogramming of CAFs in combination with immune checkpoint inhibitors has also been investigated as a possible therapeutic approach. However, although potential targets in CAFs have been widely characterized, the plasticity and heterogeneity of CAFs complicate the understanding of their properties and present difficulties for clinical application. Moreover, the identification of tumor-suppressive CAFs highlights the necessity for the development of therapeutic approaches that can distinguish and switch between tumor-promoting and tumor-suppressive CAFs in an appropriate manner. In this review, we introduce the origins and diversity of CAFs, their role in cancer, and current therapeutic strategies aimed at targeting CAFs, including ongoing clinical evaluations.

Comparison of the procoagulant activity between extracellular vesicles obtained from cellular monolayers and spheroids

Tissue factor (TF) is the main activator of blood coagulation and is associated with thrombosis and tumor progression. It can be released into the blood circulation incorporated within cancer cell-derived extracellular vesicles (EVs). In this study, we investigated the influence of two-dimensional (monolayer) and three-dimensional (spheroid) tumor cell culture methods, and co-culture with cancer-associated fibroblasts (CAF), on the level of EVs release and the associated TF release and activity. The density of EVs and TF released from spheroids and monolayers of Hs578t human breast cancer and CAF were measured by the concentration of the phosphatidylserine and TF-ELISA. For some experiments, cells were activated using a protease-activated receptor (PAR)-2-activating peptide (PAR2-AP). The concentration and EV's size were accessed by nanoparticle tracking analysis, and a clotting assay was used to evaluate TF pro-coagulant activity. Hs578t monolayers released sevenfold more EVs, and it was associated with an 11-fold higher TF antigen release than the spheroids cultures. Activation of the cells with a PAR2-AP resulted in a significant increase in the release of EVs and TF from the Hs578t monolayers, but no significant increase was observed in the spheroids, only from half Hs578t, half CAF spheroids. Taken together, our results demonstrate that monolayer cell cultures are capable of releasing more significant amounts of EVs and associated TF than spheroid cultures. Monolayers and spheroids have different behavior when we compare the release of EVs and TF. It is essential to consider it when choosing a cell model to study cancer-associated thrombosis.

Unveiling the link between chronic inflammation and cancer

The highly nuanced transition from an inflammatory process to tumorigenesis is of great scientific interest. While it is well known that environmental stimuli can cause inflammation, less is known about the oncogenic modifications that chronic inflammation in the tissue microenvironment can bring about, as well as how these modifications can set off pro-tumorigenic processes. It is clear that no matter where the environmental factors come from, maintaining an inflammatory microenvironment encourages carcinogenesis. In addition to encouraging angiogenesis and metastatic processes, sustaining the survival and proliferation of malignant transformed cells, and possibly altering the efficacy of therapeutic agents, inflammation can negatively regulate the antitumoral adaptive and innate immune responses. Because chronic inflammation has multiple pathways involved in tumorigenesis and metastasis, it has gained recognition as a marker of cancer and a desirable target for cancer therapy. Recent advances in our knowledge of the molecular mechanisms that drive cancer's progression demonstrate that inflammation promotes tumorigenesis and metastasis while suppressing anti-tumor immunity. In many solid tumor types, including breast, lung, and liver cancer, inflammation stimulates the activation of oncogenes and impairs the body's defenses against the tumor. Additionally, it alters the microenvironment of the tumor. As a tactical approach to cancer treatment, these findings have underscored the importance of targeting inflammatory pathways. This review highlights the role of inflammation in cancer development and metastasis, focusing on its impact on tumor progression, immune suppression, and therapy resistance. It examines current anti-inflammatory strategies, including NSAIDs, cytokine modulators, and STAT3 inhibitors, while addressing their potential and limitations. The review emphasizes the need for further research to unravel the complex mechanisms linking inflammation to cancer progression and identify molecular targets for specific cancer subtypes.

C3+ cancer-associated fibroblasts promote tumor growth and therapeutic resistance in gastric cancer via activation of the NF-κB signaling pathway

BACKGROUND

Gastric cancer (GC) remains one of the most lethal malignancies globally, with limited therapeutic options. Cancer-associated fibroblasts (CAFs), a diverse population of stromal cells within the tumor microenvironment (TME), play a central role in tumor progression and therapeutic resistance. However, the specific markers identifying tumor-promoting CAF subsets in GC have yet to be fully characterized.

METHODS

Through animal studies and RNA sequencing, complement C3 (C3) emerged as a key marker linked to tumor-promoting CAF subsets. Single-cell sequencing and multiplex immunofluorescence staining confirmed that C3 expression is predominantly localized within CAFs. Independent cohort analyses demonstrated a strong association between elevated levels of C3+ CAFs and poor clinical outcomes in GC patients. To further investigate, small interfering RNA (siRNA)-mediated knockdown of C3 in CAFs was employed in vitro, with subsequent experiments, including cell migration assays, cell viability assays, and immunofluorescence, revealing significant functional impacts.

RESULTS

C3 secreted by CAFs promoted Epithelial-mesenchymal transition (EMT) and accelerated cancer cell migration. Patients with minimal C3+ CAF infiltration exhibited a higher probability of deriving therapeutic benefit from adjuvant treatments. Furthermore, C3+ CAFs were associated with immunosuppressive effects and an immune-evasive microenvironment marked by CD8 + T cell dysfunction. A lower prevalence of C3+ CAFs correlated with improved responsiveness to immunotherapy in GC patients. Enrichment analysis highlighted pronounced activation of the NF-κB signaling pathway in C3+ CAFs relative to their C3- counterparts, supported by elevated phosphorylation levels of IKK, IκBα, and p65 in C3+ CAFs compared to both C3- CAFs and normal fibroblasts (NFs). Silencing p65 nuclear translocation in CAFs through siRNA significantly suppressed C3 secretion.

CONCLUSIONS

The study suggests that NF-κB pathway-mediated CAF activation enhances C3 secretion, driving EMT, migration, chemoresistance, and immune evasion in GC progression. Targeting the NF-κB/C3 signaling axis in CAFs may offer a viable therapeutic strategy for GC management.

Targeting drug resistance in breast cancer: the potential of miRNA and nanotechnology-driven delivery systems

Breast cancer is the second leading cause of cancer-related deaths in females worldwide. Despite significant advancements in treatment, drug resistance remains a major challenge, limiting the effectiveness of therapies and leading to dismal outcomes. Approximately 50% of HER2+ breast cancer patients develop resistance to trastuzumab, and patients with triple-negative breast cancer often experience resistance to first-line therapies. The drug resistance mechanisms involve altered drug uptake, enhanced DNA repair, and dysregulated apoptosis pathways. MicroRNAs are essential in regulating cellular processes involved in both homeostasis and disease. Recent data suggest that microRNAs can overcome drug resistance by regulating the pathways that confer drug resistance. Combining different conventional anticancer agents with microRNA therapies holds promise for enhancing treatment effectiveness against drug resistant breast cancer. Advancements in nano-drug delivery systems have facilitated the effective delivery of microRNAs by improving their stability, targeting specific cells, and enhancing cellular uptake. This review elucidates the recent advancements in microRNA-based therapies, their effects on gene expression, and their clinical efficacy in overcoming drug resistance in breast cancer.

Comparative transcriptome of normal and cancer-associated fibroblasts

BACKGROUND

The characteristics of a tumor are largely determined by its interaction with the surrounding micro-environment (TME). TME consists of both cellular and non-cellular components. Cancer-associated fibroblasts (CAFs) are a major component of the TME. They are a source of many secreted factors that influence the survival and progression of tumors as well as their response to drugs. Identification of markers either overexpressed in CAFs or unique to CAFs would pave the way for novel therapeutic strategies that in combination with conventional chemotherapy are likely to have better patient outcome.

METHODS

Fibroblasts have been derived from Benign Prostatic Hyperplasia (BPH) and prostate cancer. RNA from these has been used to perform a transcriptome analysis in order to get a comparative profile of normal and cancer-associated fibroblasts.

RESULTS

The study has identified 818 differentially expressed mRNAs and 17 lincRNAs between normal and cancer-associated fibroblasts. Also, 15 potential lincRNA-miRNA-mRNA combinations have been identified which may be potential biomarkers.

CONCLUSIONS

This study identified differentially expressed markers between normal and cancer-associated fibroblasts that would help in targeted therapy against CAFs/derived factors, in combination with conventional therapy. However, this would in future need more experimental validation.

Epigenetic tuning of tumour-associated macrophages (TAMs): a potential approach in hepatocellular carcinoma (HCC) immunotherapy

Recent development in immunotherapy for cancer treatment has substantiated to be more effective than most of the other treatments. Immunity is the first line of defence of the body; nevertheless, cancerous cells can manipulate immunity compartments to play several roles in tumour progression. Tumour-associated macrophages (TAMs), one of the most dominant components in the tumour microenvironment, are recognized as anti-tumour suppressors. Unfortunately, the complete behaviour of TAMs is still unclear and understudied. TAM density is directly correlated with the progression and poor prognosis of hepatocellular carcinoma (HCC), therefore studying TAMs from different points of view passing by all the factors that may affect its existence, polarization, functions and repolarization are of great importance. Different epigenetic regulations were reported to have a direct relation with both HCC and TAMs. Here, this review discusses different epigenetic regulations that can affect TAMs in HCC whether positively or negatively.

Epigenetic modification of ferroptosis by non-coding RNAs in cancer drug resistance

The development of drug resistance remains a major challenge in cancer treatment. Ferroptosis, a unique type of regulated cell death, plays a pivotal role in inhibiting tumour growth, presenting new opportunities in treating chemotherapeutic resistance. Accumulating studies indicate that epigenetic modifications by non-coding RNAs (ncRNA) can determine cancer cell vulnerability to ferroptosis. In this review, we first summarize the role of chemotherapeutic resistance in cancer growth/development. Then, we summarize the core molecular mechanisms of ferroptosis, its upstream epigenetic regulation, and its downstream effects on chemotherapeutic resistance. Finally, we review recent advances in understanding how ncRNAs regulate ferroptosis and from such modulate chemotherapeutic resistance. This review aims to enhance general understanding of the ncRNA-mediated epigenetic regulatory mechanisms which modulate ferroptosis, highlighting the ncRNA-ferroptosis axis as a key druggable target in overcoming chemotherapeutic resistance.

Drug-Resistance Biomarkers in Patient-Derived Colorectal Cancer Organoid and Fibroblast Co-Culture System

Colorectal cancer, the third most commonly occurring tumor worldwide, poses challenges owing to its high mortality rate and persistent drug resistance in metastatic cases. We investigated the tumor microenvironment, emphasizing the role of cancer-associated fibroblasts in the progression and chemoresistance of colorectal cancer. We used an indirect co-culture system comprising colorectal cancer organoids and cancer-associated fibroblasts to simulate the tumor microenvironment. Immunofluorescence staining validated the characteristics of both organoids and fibroblasts, showing high expression of epithelial cell markers (EPCAM), colon cancer markers (CK20), proliferation markers (KI67), and fibroblast markers (VIM, SMA). Transcriptome profiling was conducted after treatment with anticancer drugs, such as 5-fluorouracil and oxaliplatin, to identify chemoresistance-related genes. Changes in gene expression in the co-cultured colorectal cancer organoids following anticancer drug treatment, compared to monocultured organoids, particularly in pathways related to interferon-alpha/beta signaling and major histocompatibility complex class II protein complex assembly, were identified. These two gene groups potentially mediate drug resistance associated with JAK/STAT signaling. The interaction between colorectal cancer organoids and fibroblasts crucially modulates the expression of genes related to drug resistance. These findings suggest that the interaction between colorectal cancer organoids and fibroblasts significantly influences gene expression related to drug resistance, highlighting potential biomarkers and therapeutic targets for overcoming chemoresistance. Enhanced understanding of the interactions between cancer cells and their microenvironment can lead to advancements in personalized medical research..

The role of CXCL1 in crosstalk between endocrine resistant breast cancer and fibroblast

BACKGROUND

ER positive breast cancer is currently targeted using various endocrine therapies. Despite the proven therapeutic efficacy, resistance to the drug and reoccurrence of tumor appears to be a complication that many patients deal with. Molecular pathways underlying the development of resistance are being widely studied.

METHODS AND RESULTS

In this study, using four established endocrine resistant breast cancer (ERBC) cell lines, we characterized CXCL1 as a secreted factor in crosstalk between ERBC cells and fibroblasts. Protein array revealed upregulation of CXCL1 and we confirmed the CXCL1 expression by real-time qRT-PCR and U-Plex assay. Co-culturing ERBC cells with fibroblasts enhanced the cell growth and migration compared to monoculture. The crosstalk of ERBC cells with fibroblasts significantly activates ERK/MAPK signaling pathway while reparixin, CXCR1/2 receptor inhibitor, attenuates the activity. Reparixin displayed the ERBC cell growth inhibition and the combination treatment with reparixin and CDK4/6 inhibitor (palbociclib and ribociclib) increased these inhibitory effect.

CONCLUSIONS

Taken together, our study implicates CXCL1 as a critical role in ERBC growth and metastasis via crosstalk with fibroblast and cotargeting CXCR1/2 and CDK4/6 could potentially overcome endocrine resistant breast cancer.

Exploring Tumor-Promoting Qualities of Cancer-Associated Fibroblasts and Innovative Drug Discovery Strategies With Emphasis on Thymoquinone

Tumor epithelial development and chemoresistance are highly promoted by the tumor microenvironment (TME), which is mostly made up of the cancer stroma. This is due to several causes. Cancer-associated fibroblasts (CAFs) stand out among them as being essential for the promotion of tumors. Understanding the fibroblastic population within a single tumor is made more challenging by the undeniable heterogeneity within it, even though particular stromal alterations are still up for debate. Numerous chemical signals released by tumors improve the connections between heterotypic fibroblasts and CAFs, promoting the spread of cancer. It becomes essential to have a thorough understanding of this complex microenvironment to effectively prevent solid tumor growth. Important new insights into the role of CAFs in the TME have been revealed by recent studies. The objective of this review is to carefully investigate the relationship between CAFs in tumors and plant secondary metabolites, with a focus on thymoquinone (TQ). The literature published between 2010 and 2023 was searched in PubMed and Google Scholar with keywords such as TQ, TME, cancer-associated fibroblasts, mechanism of action, and flavonoids. The results showed a wealth of data substantiating the activity of plant secondary metabolites, particularly TQ's involvement in blocking CAF operations. Scrutinized research also clarified the wider effect of flavonoids on pathways related to cancer. The present study highlights the complex dynamics of the TME and emphasizes the critical role of CAFs. It also examines the possible interventions provided by secondary metabolites found in plants, with TQ playing a vital role in regulating CAF function based on recent literature.

AKT2S128/CCTαS315/319/323-positive cancer-associated fibroblasts (CAFs) mediate focal adhesion kinase (FAK) inhibitors resistance via secreting phosphatidylcholines (PCs)

Abnormal metabolism is regarded as an oncogenic hallmark related to tumor progression and therapeutic resistance. Present study employed multi-omics, including phosphoproteomics, untargeted metabolomics and lipidomics, to demonstrate that the pAKT2 Ser128 and pCCTα Ser315/319/323-positive cancer-associated fibroblasts (CAFs) substantially release phosphatidylcholines (PCs), contributing to the resistance of focal adhesion kinase (FAK) inhibitors in esophageal squamous cell carcinoma (ESCC) treatment. Additionally, we observed extremely low levels of FAK Tyr397 expression in CAFs, potentially offering no available target for FAK inhibitors playing their anti-growth role in CAFs. Consequently, FAK inhibitor increased the intracellular concentration of Ca2+ in CAFs, promoting the formation of AKT2/CCTα complex, leading to phosphorylation of CCTα Ser315/319/323 sites and eventually enhancing stromal PC production. This activation could stimulate the intratumoral Janus kinase 2 (JAK2)/Signal transducer and activator of transcription 3 (STAT3) pathway, triggering resistance to FAK inhibition. Analysis of clinical samples demonstrated that stromal pAKT2 Ser128 and pCCTα Ser315/319/323 are related to the tumor malignancy and reduced patient survival. Pseudo-targeted lipidomics and further validation cohort quantitatively showed that plasma PCs enable to distinguish the malignant extent of ESCC patients. In conclusion, inhibition of stroma-derived PCs and related pathway could be possible therapeutic strategies for tumor therapy.

Mesothelial cells with mesenchymal features enhance peritoneal dissemination by forming a protumorigenic microenvironment

Malignant ascites accompanied by peritoneal dissemination contain various factors and cell populations as well as cancer cells; however, how the tumor microenvironment is shaped in ascites remains unclear. Single-cell proteomic profiling and a comprehensive proteomic analysis are conducted to comprehensively characterize malignant ascites. Here, we find defects in immune effectors along with immunosuppressive cell accumulation in ascites of patients with gastric cancer (GC) and identify five distinct subpopulations of CD45(-)/EpCAM(-) cells. Mesothelial cells with mesenchymal features in CD45(-)/EpCAM(-) cells are the predominant source of chemokines involved in immunosuppressive myeloid cell (IMC) recruitment. Moreover, mesothelial-mesenchymal transition (MMT)-induced mesothelial cells strongly express extracellular matrix (ECM)-related genes, including tenascin-C (TNC), enhancing metastatic colonization. These findings highlight the definite roles of the mesenchymal cell population in the development of a protumorigenic microenvironment to promote peritoneal dissemination.

DRMref: comprehensive reference map of drug resistance mechanisms in human cancer

Drug resistance poses a significant challenge in cancer treatment. Despite the initial effectiveness of therapies such as chemotherapy, targeted therapy and immunotherapy, many patients eventually develop resistance. To gain deep insights into the underlying mechanisms, single-cell profiling has been performed to interrogate drug resistance at cell level. Herein, we have built the DRMref database (https://ccsm.uth.edu/DRMref/) to provide comprehensive characterization of drug resistance using single-cell data from drug treatment settings. The current version of DRMref includes 42 single-cell datasets from 30 studies, covering 382 samples, 13 major cancer types, 26 cancer subtypes, 35 treatment regimens and 42 drugs. All datasets in DRMref are browsable and searchable, with detailed annotations provided. Meanwhile, DRMref includes analyses of cellular composition, intratumoral heterogeneity, epithelial-mesenchymal transition, cell-cell interaction and differentially expressed genes in resistant cells. Notably, DRMref investigates the drug resistance mechanisms (e.g. Aberration of Drug's Therapeutic Target, Drug Inactivation by Structure Modification, etc.) in resistant cells. Additional enrichment analysis of hallmark/KEGG (Kyoto Encyclopedia of Genes and Genomes)/GO (Gene Ontology) pathways, as well as the identification of microRNA, motif and transcription factors involved in resistant cells, is provided in DRMref for user's exploration. Overall, DRMref serves as a unique single-cell-based resource for studying drug resistance, drug combination therapy and discovering novel drug targets.

Differential effect of cancer-associated fibroblast-derived extracellular vesicles on cisplatin resistance in oral squamous cell carcinoma via miR-876-3p

Rationale: Platinum-based chemotherapy is commonly used for treating solid tumors, but drug resistance often limits its effectiveness. Cancer-associated fibroblast (CAF)-derived extracellular vesicle (EV), which carry various miRNAs, have been implicated in chemotherapy resistance. However, the molecular mechanism through which CAFs modulate cisplatin resistance in oral squamous cell carcinoma (OSCC) is not well understood. We employed two distinct primary CAF types with differential impacts on cancer progression: CAF-P, representing a more aggressive cancer-promoting category, and CAF-D, characterized by properties that moderately delay cancer progression. Consequently, we sought to investigate whether the two CAF types differentially affect cisplatin sensitivity and the underlying molecular mechanism. Methods: The secretion profile was examined by utilizing an antibody microarray with conditioned medium obtained from the co-culture of OSCC cells and two types of primary CAFs. The effect of CAF-dependent factors on cisplatin resistance was investigated by utilizing conditioned media (CM) and extracellular vesicle (EVs) derived from CAFs. The impacts of candidate genes were confirmed using gain- and loss-of-function analyses in spheroids and organoids, and a mouse xenograft. Lastly, we compared the expression pattern of the candidate genes in tissues from OSCC patients exhibiting different responses to cisplatin. Results: When OSCC cells were cultured with conditioned media (CM) from the two different CAF groups, cisplatin resistance increased only under CAF-P CM. OSCC cells specifically expressed insulin-like growth factor binding protein 3 (IGFBP3) after co-culture with CAF-D. Meanwhile, IGFBP3-knockdown OSCC cells acquired cisplatin resistance in CAF-D CM. IGFBP3 expression was promoted by GATA-binding protein 1 (GATA1), a transcription factor targeted by miR-876-3p, which was enriched only in CAF-P-derived EV. Treatment with CAF-P EV carrying miR-876-3p antagomir decreased cisplatin resistance compared to control miRNA-carrying CAF-P EV. On comparing the staining intensity between cisplatin-sensitive and -insensitive tissues from OSCC patients, there was a positive correlation between IGFBP3 and GATA1 expression and cisplatin sensitivity in OSCC tissues from patients. Conclusion: These results provide insights for overcoming cisplatin resistance, especially concerning EVs within the tumor microenvironment. Furthermore, it is anticipated that the expression levels of GATA1 and miR-876-3p, along with IGFBP3, could aid in the prediction of cisplatin resistance.

Improved Drug-Response Prediction Model of APC Mutant Colon Cancer Patient-Derived Organoids for Precision Medicine

Colorectal cancer is the third most common cancer in the world, with an annual incidence of 2 million cases. The success of first-line chemotherapy plays a crucial role in determining the disease outcome. Therefore, there is an increasing demand for precision medicine to predict drug responses and optimize chemotherapy in order to increase patient survival and reduce the related side effects. Patient-derived organoids have become a popular in vitro screening model for drug-response prediction for precision medicine. However, there is no established correlation between oxaliplatin and drug-response prediction. Here, we suggest that organoid culture conditions can increase resistance to oxaliplatin during drug screening, and we developed a modified medium condition to address this issue. Notably, while previous studies have shown that survivin is a mechanism for drug resistance, our study observed consistent survivin expression irrespective of the culture conditions and oxaliplatin treatment. However, clusterin induced apoptosis inhibition and cell survival, demonstrating a significant correlation with drug resistance. This study's findings are expected to contribute to increasing the accuracy of drug-response prediction in patient-derived APC mutant colorectal cancer organoids, thereby providing reliable precision medicine and improving patient survival rates.

Cancer-associated fibroblasts reuse cancer-derived lactate to maintain a fibrotic and immunosuppressive microenvironment in pancreatic cancer

Glycolysis is highly enhanced in pancreatic ductal adenocarcinoma (PDAC) cells; thus, glucose restrictions are imposed on nontumor cells in the PDAC tumor microenvironment (TME). However, little is known about how such glucose competition alters metabolism and confers phenotypic changes in stromal cells in the TME. Here, we report that cancer-associated fibroblasts (CAFs) with restricted glucose availability utilize lactate from glycolysis-enhanced cancer cells as a fuel and exert immunosuppressive activity in the PDAC TME. The expression of lactate dehydrogenase A (LDHA), which regulates lactate production, was a poor prognostic factor for patients with PDAC, and LDHA depletion suppressed tumor growth in a CAF-rich murine PDAC model. Coculture of CAFs with PDAC cells revealed that most of the glucose was taken up by the tumor cells and that CAFs consumed lactate via monocarboxylate transporter 1 to enhance proliferation through the TCA cycle. Moreover, lactate-stimulated CAFs upregulated IL-6 expression and suppressed cytotoxic immune cell activity synergistically with lactate. Finally, the LDHA inhibitor FX11 reduced tumor growth and improved antitumor immunity in CAF-rich PDAC tumors. Our study provides insight regarding the crosstalk among tumor cells, CAFs, and immune cells mediated by lactate and offers therapeutic strategies for targeting LDHA enzymatic activity in PDAC cells.

Potential mechanisms of cancer-associated fibroblasts in therapeutic resistance

Despite continuous improvements in research and new cancer therapeutics, the goal of eradicating cancer remains elusive because of drug resistance. For a long time, drug resistance research has been focused on tumor cells themselves; however, recent studies have found that the tumor microenvironment also plays an important role in inducing drug resistance. Cancer-associated fibroblasts (CAFs) are a main component of the tumor microenvironment. They cross-talk with cancer cells to support their survival in the presence of anticancer drugs. This review summarizes the current knowledge of the role of CAFs in tumor drug resistance. An in-depth understanding of the mechanisms underlying the cross-talk between CAFs and cancer cells and insight into the importance of CAFs in drug resistance can guide the development of new anticancer strategies.

The role of Extracellular Vesicles in glycolytic and lipid metabolic reprogramming of cancer cells: Consequences for drug resistance

In order to adapt to a higher proliferative rate and an increased demand for energy sources, cancer cells rewire their metabolic pathways, a process currently recognized as a hallmark of cancer. Even though the metabolism of glucose is perhaps the most discussed metabolic shift in cancer, lipid metabolic alterations have been recently recognized as relevant players in the growth and proliferation of cancer cells. Importantly, some of these metabolic alterations are reported to induce a drug resistant phenotype in cancer cells. The acquisition of drug resistance traits severely hinders cancer treatment, being currently considered one of the major challenges of the oncological field. Evidence suggests that Extracellular Vesicles (EVs), which play a crucial role in intercellular communication, may act as facilitators of tumour progression, survival and drug resistance by modulating several aspects involved in the metabolism of cancer cells. This review aims to gather and discuss relevant data regarding metabolic reprograming in cancer, particularly involving the glycolytic and lipid alterations, focusing on its influence on drug resistance and highlighting the relevance of EVs as intercellular mediators of this process.

PLEKHA4 is a novel prognostic biomarker that reshapes the tumor microenvironment in lower-grade glioma

Background

Lower-grade glioma (LGG) is a primary intracranial tumor that carry a high risk of malignant transformation and limited therapeutic options. Emerging evidence indicates that the tumor microenvironment (TME) is a superior predictor for tumor progression and therapy response. PLEKHA4 has been demonstrated to be a biomarker for LGG that correlate with immune infiltration. However, the fundamental mechanism by which PLEKHA4 contributes to LGG is still poorly understood.

Methods

Multiple bioinformatic tools, including Tumor Immune Estimation Resource (TIMER), Gene Expression Profiling Interactive Analysis (GEPIA2), Shiny Methylation Analysis Resource Tool (SMART), etc., were incorporated to analyze the PLEKHA4. ESTIMATE, ssGSEA, CIBERSORT, TIDE and CellMiner algorithms were employed to determine the association of PLEKHA4 with TME, immunotherapy response and drug sensitivities. Immunohistochemistry (IHC)-based tissue microarrays and M2 macrophage infiltration assay were conducted to verify their associations.

Results

PLEKHA4 expression was found to be dramatically upregulated and strongly associated with unfavorable overall survival (OS) and disease-specific survival (DSS) in LGG patients, as well as their poor clinicopathological characteristics. Cox regression analysis identified that PLEKHA4 was an independent prognostic factor. Methylation analysis revealed that DNA methylation correlates with PLEKHA4 expression and indicates a better outcome in LGG. Moreover, PLEKHA4 was remarkably correlated with immune responses and TME remodeling, as evidenced by its positive correlation with particular immune marker subsets and the putative infiltration of immune cells. Surprisingly, the proportion of M2 macrophages in TME was strikingly higher than others, inferring that PLEKHA4 may regulate the infiltration and polarization of M2 macrophages. Evidence provided by IHC-based tissue microarrays and M2 macrophage infiltration assay further validated our findings. Moreover, PLEKHA4 expression was found to be significantly correlated with chemokines, interleukins, and their receptors, further supporting the critical role of PLEKHA4 in reshaping the TME. Additionally, we found that PLEKHA4 expression was closely associated with drug sensitivities and immunotherapy responses, indicating that PLEKHA4 expression also had potential clinical significance in guiding immunotherapy and chemotherapy in LGG.

Conclusion

PLEKHA4 plays a pivotal role in reshaping the TME of LGG patients, and may serve as a potential predictor for LGG prognosis and therapy.

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.

The role of cancer-associated fibroblasts in bladder cancer progression

Cancer-associated fibroblasts (CAFs) are key stromal cells in the tumor microenvironment (TME) that critically contribute to cancer initiation and progression. In bladder cancer (BCa), there is emerging evidence that BCa CAFs are actively involved in cancer cell proliferation, invasion, metastasis, and chemotherapy resistance. This review outlines the present knowledge of BCa CAFs, with a particular emphasis on their origin and function in BCa progression, and provides further insights into their clinical application.

Biofabrication of Modular Spheroids as Tumor-Scale Microenvironments for Drug Screening

To streamline the drug discovery pipeline, there is a pressing need for preclinical models which replicate the complexity and scale of native tumors. While there have been advancements in the formation of microscale tumor units, these models are cell-line dependent, time-consuming and have not improved clinical trial success rates. In this study, two methods for generating 3D tumor microenvironments are compared, rapidly fabricated hydrogel microspheres and traditional cell-dense spheroids. These modules are then bioassembled into 3D printed thermoplastic scaffolds, using an automated biofabrication process, to form tumor-scale models. Modules are formed with SKOV3 and HFF cells as monocultures and cocultures, and the fabrication efficiency, cell architecture, and drug response profiles are characterized, both as single modules and as multimodular constructs. Cell-encapsulated Gel-MA microspheres are fabricated with high-reproducibility and dimensions necessary for automated tumor-scale bioassembly regardless of cell type, however, only cocultured spheroids form compact modules suitable for bioassembly. Chemosensitivity assays demonstrate the reduced potency of doxorubicin in coculture bioassembled constructs and a ≈five-fold increase in drug resistance of cocultured cells in 3D modules compared with 2D monolayers. This bioassembly system is efficient and tailorable so that a variety of relevant-sized tumor constructs could be developed to study tumorigenesis and modernize drug discovery.

A novel tdTomato transgenic mouse model to visualize FAP-positive cancer-associated fibroblasts

Fibroblast activation protein (FAP) generally shows low or undetectable expression in most normal tissues but is highly expressed in fibroblasts in almost all carcinomas. FAP is one of the potential molecules to detect activated fibroblasts and has multiple roles in tumour progression. We generated transgenic mice that specifically expressed tdTomato along with FAP promoter activity. Coculturing a mouse gastric cancer cell line and FAP-tdTomato transgenic mouse-derived fibroblasts showed that tdTomato expression was elevated in the cocultured fibroblasts. Moreover, stomach wall transplanted tumours in mice also showed FAP-tdTomato expression in fibroblasts of the stomach and each metastatic legion. These results indicated that FAP-tdTomato expression in fibroblasts was elevated by stimulation through the interaction with cancer cells. Functionally, collagen production was increased in FAP/tdTomato-positive fibroblasts cocultured with mouse cancer cells. These FAP-tdTomato transgenic mice have the potential to be used to investigate real-time FAP dynamics and the importance of FAP expression in tumour development.

The characterization of the sensitive ovarian cancer cell lines A2780 and W1 in response to ovarian CAFs

PURPOSE

The cancer-associated fibroblasts (CAFs) are one of the most abundant components of the tumor microenvironment (TME). CAFs have been implicated in tumor progression, extracellular matrix (ECM) remodeling, and treatment resistance. Drug resistance is the primary limiting factor in achieving cures for patients with cancer, particularly ovarian cancer. Therefore, inhibiting CAFs can be an effective strategies for cancer treatment. In this research, we studied whether CAFs have an influence on drug-sensitive ovarian cancer cells to become more resistant. We examined the influence of CAFs on genes and proteins expression changes in sensitive ovarian cancer cells. We prepared a 3D co-culture to investigate the role of CAFs on cancer cell morphology.

METHODS

Here, we performed a detailed analysis of drug-sensitive ovarian cancer cell lines (A2780 and W1) and the influence of ovarian CAFs on the A2780 and W1 cells morphology, genes and proteins expression. The 2D and 3D cultures, genes expression analysis (TaqMan qPCR), and proteins expression (Western blot analysis) were assessed in this study.

RESULTS

We observed upregulation of ABCC5, CYP2C8, CYP2C9, and DHFR mRNA in cell lines supplemented by CAFs medium. We showed fibronectin overexpression and COL3A1 downregulation after supplementation with CAFs. Co-culturing with CAFs prevented the formation of spheroids in 3D conditions.

CONCLUSION

We demonstrated that the process of drug resistance in ovarian cancer cells is launched by CAFs. CAFs not only simulate cancer cells to produce drug transporters and specific enzymes production, but also remodel the TME to increase drug resistance. We believe that cancer progression and migration is due to the CAFs po-tumorigenic activity.

Heterotypic signaling of cancer-associated fibroblasts in shaping the cancer cell drug resistance

The context-dependent reciprocal interaction between the cancer cells and surrounding fibroblasts is imperative for regulating malignant potential, metabolic reprogramming, immunosuppression, and ECM deposition. However, recent evidence also suggests that cancer-associated fibroblasts induce chemoresistance in cancer cells to various anticancer regimens. Because of the protumorigenic function of cancer-associated fibroblasts, these stromal cell types have emerged as fascinating therapeutic targets for cancer. However, this notion was recently challenged by studies that targeted cancer-associated fibroblasts and highlighted the underlying heterogeneity by identifying a subset of these cells with tumor-restricting functions. Hence, it is imperative to understand the heterogeneity and heterotypic signaling of cancer-associated fibroblasts to target tumor-promoting signaling processes by sparing tumor-restricting ones. In this review, we discuss the heterogeneity and heterotypic signaling of cancer-associated fibroblasts in shaping drug resistance and also list the cancer-associated fibroblast-targeting therapeutics.

Dual-drug codelivery nanosystems: An emerging approach for overcoming cancer multidrug resistance

Multidrug resistance (MDR) promotes tumor recurrence and metastasis and heavily reduces anticancer efficiency, which has become a primary reason for the failure of clinical chemotherapy. The mechanisms of MDR are so complex that conventional chemotherapy usually fails to achieve an ideal therapeutic effect and even accelerates the occurrence of MDR. In contrast, the combination of chemotherapy with dual-drug has significant advantages in tumor therapy. A novel dual-drug codelivery nanosystem, which combines dual-drug administration with nanotechnology, can overcome the application limitation of free drugs. Both the characteristics of nanoparticles and the synergistic effect of dual drugs contribute to circumventing various drug-resistant mechanisms in tumor cells. Therefore, developing dual-drug codelivery nanosystems with different multidrug-resistant mechanisms has an important reference value for reversing MDR and enhancing the clinical antitumor effect. In this review, the advantages, principles, and common codelivery nanocarriers in the application of dual-drug codelivery systems are summarized. The molecular mechanisms of MDR and the dual-drug codelivery nanosystems designed based on different mechanisms are mainly introduced. Meanwhile, the development prospects and challenges of codelivery nanosystems are also discussed, which provide guidelines to exploit optimized combined chemotherapy strategies in the future.

Stromal Reprogramming through Dual PDGFRα/β Blockade Boosts the Efficacy of Anti-PD-1 Immunotherapy in Fibrotic Tumors

Excess stroma and cancer-associated fibroblasts (CAF) enhance cancer progression and facilitate immune evasion. Insights into the mechanisms by which the stroma manipulates the immune microenvironment could help improve cancer treatment. Here, we aimed to elucidate potential approaches for stromal reprogramming and improved cancer immunotherapy. Platelet-derived growth factor C (PDGFC) and D expression were significantly associated with a poor prognosis in patients with gastric cancer, and PDGF receptor beta (PDGFRβ) was predominantly expressed in diffuse-type gastric cancer stroma. CAFs stimulated with PDGFs exhibited markedly increased expression of CXCL1, CXCL3, CXCL5, and CXCL8, which are involved in polymorphonuclear myeloid-derived suppressor cell (PMN-MDSC) recruitment. Fibrotic gastric cancer xenograft tumors exhibited increased PMN-MDSC accumulation and decreased lymphocyte infiltration, as well as resistance to anti-PD-1. Single-cell RNA sequencing and spatial transcriptomics revealed that PDGFRα/β blockade reversed the immunosuppressive microenvironment through stromal modification. Finally, combining PDGFRα/β blockade and anti-PD-1 treatment synergistically suppressed the growth of fibrotic tumors. These findings highlight the impact of stromal reprogramming on immune reactivation and the potential for combined immunotherapy for patients with fibrotic cancer.

SIGNIFICANCE

Stromal targeting with PDGFRα/β dual blockade reverses the immunosuppressive microenvironment and enhances the efficacy of immune checkpoint inhibitors in fibrotic cancer. See related commentary by Tauriello, p. 655.

Cellular senescence in the tumor microenvironment and context-specific cancer treatment strategies

Cellular senescence in cancer development is known to have tumor-suppressive and tumor-promoting roles. Recent studies have revealed numerous molecular mechanisms of senescence followed by senescence-associated secretory phenotype induction and showed the significance of senescence on both sides. Cellular senescence in stromal cells is one of the reasons for therapeutic resistance in advanced cancer; thus, it is an inevitable phenomenon to address while seeking an effective cancer treatment strategy. This review summarizes the molecular mechanisms regarding cellular senescence, focusing on the dual roles played by senescence, and offers some direction toward successful treatments targeting harmful senescent cells.

Role of cancer-associated fibroblasts in colorectal cancer

Colorectal cancer (CRC) is a malignancy that has a high incidence in all countries around the world. Cancer-associated fibroblasts (CAFs) are a vital component of the tumor microenvironment (TME), playing an important role in the development of CRC. CAFs can release multiple cytokines and exosomes, activating a variety of related signaling pathways and boosting the processes of the invasion, metastasis, metabolism, drug resistance, and immunosuppression in CRC. Thus, CAFs are a prognostic marker and therapeutic target for CRC. Understanding the role and mechanism of CAFs can provide new insights for the treatment of CRC.

Role of cancer-associated fibroblasts in colorectal cancer

Colorectal cancer (CRC) is a malignancy that has a high incidence in all countries around the world. Cancer-associated fibroblasts (CAFs) are a vital component of the tumor microenvironment (TME), playing an important role in the development of CRC. CAFs can release multiple cytokines and exosomes, activating a variety of related signaling pathways and boosting the processes of the invasion, metastasis, metabolism, drug resistance, and immunosuppression in CRC. Thus, CAFs are a prognostic marker and therapeutic target for CRC. Understanding the role and mechanism of CAFs can provide new insights for the treatment of CRC.

Periostin secreted from podoplanin-positive cancer-associated fibroblasts promotes metastasis of gastric cancer by regulating cancer stem cells via AKT and YAP signaling pathway

Cancer-associated fibroblasts (CAFs) are heterogeneous stromal cells present in the tumor microenvironment (TME), which play a critical role in gastric cancer (GC) progression. Here, we examined a subset of CAFs with high podoplanin (PDPN) expression, which is correlated with tumor metastasis and poor survival in GC patients. Animal models of gastric cancer liver metastasis monitored by micro-PET/CT confirmed that periostin (POSTN) derived from PDPN(+) CAFs regulated CAFs' pro-migratory ability. Mechanistically, PDPN(+) CAFs secreted POSTN to modulate cancer stem cells (CSCs) through FAK/AKT phosphorylation. Furthermore, POSTN could also activate FAK/YAP signaling in GC cells to produce increased amounts of IL-6, which in turn induced phosphorylation of PI3K/AKT in PDPN(+) CAFs. Prolonged PI3K/AKT pathway activation in PDPN(+) CAFs maintains the production of POSTN and the effect on CSC enrichment and GC cell migration. In conclusion, our study demonstrated a positive feedback loop between PDPN(+) CAFs and CSCs during GC progression and suggested a selective target for GC treatment.

Targeting the tumor stroma for cancer therapy

Tumors are comprised of both cancer cells and surrounding stromal components. As an essential part of the tumor microenvironment, the tumor stroma is highly dynamic, heterogeneous and commonly tumor-type specific, and it mainly includes noncellular compositions such as the extracellular matrix and the unique cancer-associated vascular system as well as a wide variety of cellular components including activated cancer-associated fibroblasts, mesenchymal stromal cells, pericytes. All these elements operate with each other in a coordinated fashion and collectively promote cancer initiation, progression, metastasis and therapeutic resistance. Over the past few decades, numerous studies have been conducted to study the interaction and crosstalk between stromal components and neoplastic cells. Meanwhile, we have also witnessed an exponential increase in the investigation and recognition of the critical roles of tumor stroma in solid tumors. A series of clinical trials targeting the tumor stroma have been launched continually. In this review, we introduce and discuss current advances in the understanding of various stromal elements and their roles in cancers. We also elaborate on potential novel approaches for tumor-stroma-based therapeutic targeting, with the aim to promote the leap from bench to bedside.

The extracellular matrix alteration, implication in modulation of drug resistance mechanism: friends or foes?

The extracellular matrix (ECM) is an important component of the tumor microenvironment (TME), having several important roles related to the hallmarks of cancer. In cancer, multiple components of the ECM have been shown to be altered. Although most of these alterations are represented by the increased or decreased quantity of the ECM components, changes regarding the functional alteration of a particular ECM component or of the ECM as a whole have been described. These alterations can be induced by the cancer cells directly or by the TME cells, with cancer-associated fibroblasts being of particular interest in this regard. Because the ECM has this wide array of functions in the tumor, preclinical and clinical studies have assessed the possibility of targeting the ECM, with some of them showing encouraging results. In the present review, we will highlight the most relevant ECM components presenting a comprehensive description of their physical, cellular and molecular properties which can alter the therapy response of the tumor cells. Lastly, some evidences regarding important biological processes were discussed, offering a more detailed understanding of how to modulate altered signalling pathways and to counteract drug resistance mechanisms in tumor cells.

Profiling the 3D interaction between germ cell tumors and microenvironmental cells at the transcriptome and secretome level

The tumor microenvironment (TM), consisting of the extracellular matrix (ECM), fibroblasts, endothelial cells, and immune cells, might affect tumor invasiveness and the outcome of standard chemotherapy. This study investigated the cross talk between germ cell tumors (GCT) and surrounding TM cells (macrophages, T-lymphocytes, endothelial cells, and fibroblasts) at the transcriptome and secretome level. Using high-throughput approaches of three-dimensional (3D) co-cultured cellular aggregates, this study offers newly identified pathways to be studied with regard to sensitivity toward cisplatin-based chemotherapy or tumor invasiveness as a consequence of the cross talk between tumor cells and TM components. Mass-spectrometry-based secretome analyses revealed that TM cells secreted factors involved in ECM organization, cell adhesion, angiogenesis, and regulation of insulin-like growth factor (IGF) transport. To evaluate direct cell-cell contacts, green fluorescent protein (GFP)-expressing GCT cells and mCherry-expressing TM cells were co-cultured in 3D. Afterward, cell populations were separated by flow cytometry and analyzed by RNA sequencing. Correlating the secretome with transcriptome data indicated molecular processes such as cell adhesion and components of the ECM being enriched in most cell populations. Re-analyses of secretome data with regard to lysine- and proline-hydroxylated peptides revealed a gain in proteins, such as collagens and fibronectin. Cultivation of GCT cells on collagen I/IV- or fibronectin-coated plates significantly elevated adhesive and migratory capacity, while decreasing cisplatin sensitivity of GCT cells. Correspondingly, cisplatin sensitivity was significantly reduced in GCT cells under the influence of conditioned medium from fibroblasts and endothelial cells. This study sheds light on the cross talk between GCT cells and their circumjacent TM, which results in deposition of the ECM and eventually promotes a pro-tumorigenic environment through enhanced migratory and adhesive capacity, as well as decreased cisplatin sensitivity. Hence, our observations indicate that targeting the ECM and its cellular components might be a novel therapeutic option in combination with cisplatin-based chemotherapy for GCT patients.

Mechanisms of chemotherapeutic resistance and the application of targeted nanoparticles for enhanced chemotherapy in colorectal cancer

Colorectal cancer is considered one of the major malignancies that threaten the lives and health of people around the world. Patients with CRC are prone to post-operative local recurrence or metastasis, and some patients are advanced at the time of diagnosis and have no chance for complete surgical resection. These factors make chemotherapy an indispensable and important tool in treating CRC. However, the complex composition of the tumor microenvironment and the interaction of cellular and interstitial components constitute a tumor tissue with high cell density, dense extracellular matrix, and high osmotic pressure, inevitably preventing chemotherapeutic drugs from entering and acting on tumor cells. As a result, a novel drug carrier system with targeted nanoparticles has been applied to tumor therapy. It can change the physicochemical properties of drugs, facilitate the crossing of drug molecules through physiological and pathological tissue barriers, and increase the local concentration of nanomedicines at lesion sites. In addition to improving drug efficacy, targeted nanoparticles also reduce side effects, enabling safer and more effective disease diagnosis and treatment and improving bioavailability. In this review, we discuss the mechanisms by which infiltrating cells and other stromal components of the tumor microenvironment comprise barriers to chemotherapy in colorectal cancer. The research and application of targeted nanoparticles in CRC treatment are also classified.

Identification of key genes and pathways related to cancer-associated fibroblasts in chemoresistance of ovarian cancer cells based on GEO and TCGA databases

Background

Studies have revealed the implications of cancer-associated fibroblasts (CAFs) in tumor progression, metastasis, and treatment resistance. Here, in silico analyses were performed to reveal the key genes and pathways by which CAFs affected chemoresistance in ovarian cancer.

Methods

Candidate genes were obtained from the intersected differentially expressed genes in ovarian cancer, ovarian cancer chemoresistance, and ovarian CAF-related microarrays and chemoresistance-related genes from GeneCards databases. Kyoto Encyclopedia of Genes and Genomes enrichment analysis and Gene Set Enrichment Analysis were employed to identify the pathways engaged in ovarian cancer chemoresistance and ovarian CAF-related pathways. The top genes with high Degree in the protein-protein interaction network were intersected with the top genes enriched in the key pathways, followed by correlation analyses between key genes and chemotherapeutic response. The expression profiles of key genes were obtained from Human Protein Atlas database and TCGA-ovarian cancer data.

Results

p53, cell cycle, PI3K-Akt, and MAPK pathways were the key pathways related to the implication of CAFs in ovarian cancer chemoresistance. 276 candidate genes differentially expressed in CAFs were associated with ovarian cancer chemoresistance. MYC, IGF1, HRAS, CCND1, AKT1, RAC1, KDR, FGF2, FAS, and EGFR were enriched in the key chemoresistance-related ways. Furthermore, MYC, EGFR, CCND1 exhibited close association with chemotherapeutic response to platinum and showed a high expression in ovarian cancer tissues and platinum-resistant ovarian cancer cells.

Conclusion

The study suggests the key genes (MYC, EGFR, and CCND1) and pathways (p53, cell cycle, PI3K-Akt, and MAPK) responsible for the effect of CAFs on ovarian cancer chemoresistance.

Generation and Characterization of a Tumor Stromal Microenvironment and Analysis of Its Interplay with Breast Cancer Cells: An In Vitro Model to Study Breast Cancer-Associated Fibroblast Inactivation

Breast cancer-associated fibroblasts (BCAFs), the most abundant non-cancer stromal cells of the breast tumor microenvironment (TME), dramatically sustain breast cancer (BC) progression by interacting with BC cells. BCAFs, as well as myofibroblasts, display an up regulation of activation and inflammation markers represented by α-smooth muscle actin (α-SMA) and cyclooxygenase 2 (COX-2). BCAF aggregates have been identified in the peripheral blood of metastatic BC patients. We generated an in vitro stromal model consisting of human primary BCAFs grown as monolayers or 3D cell aggregates, namely spheroids and reverted BCAFs, obtained from BCAF spheroids reverted to 2D cell adhesion growth after 216 h of 3D culture. We firstly evaluated the state of activation and inflammation and the mesenchymal status of the BCAF monolayers, BCAF spheroids and reverted BCAFs. Then, we analyzed the MCF-7 cell viability and migration following treatment with conditioned media from the different BCAF cultures. After 216 h of 3D culture, the BCAFs acquired an inactivated phenotype, associated with a significant reduction in α-SMA and COX-2 protein expression. The deactivation of the BCAF spheroids at 216 h was further confirmed by the cytostatic effect exerted by their conditioned medium on MCF-7 cells. Interestingly, the reverted BCAFs also retained a less activated phenotype as indicated by α-SMA protein expression reduction. Furthermore, the reverted BCAFs exhibited a reduced pro-tumor phenotype as indicated by the anti-migratory effect exerted by their conditioned medium on MCF-7 cells. The deactivation of BCAFs without drug treatment is possible and leads to a reduced capability of BCAFs to sustain BC progression in vitro. Consequently, this study could be a starting point to develop new therapeutic strategies targeting BCAFs and their interactions with cancer cells.

Field carcinogenesis and biological significance of the potential of the bystander effect: carcinogenesis, therapeutic response, and tissue regeneration

The "bystander effect" is a transmission phenomenon mediating communication from target to non-target cells, as well as cell-to-cell interactions between neighboring and distantly located cells. In this narrative review, we describe the fundamental and clinical significance of the bystander effect with respect to cell-to-cell interactions in carcinogenesis, therapeutic response, and tissue regeneration. In carcinogenesis, the bystander effect mediates communications between tumor microenvironments and non-malignant epithelial cells and has been suggested to impact heterogeneous tumorigenic cells in tumors and cancerized fields. In therapeutic response, the bystander effect mediates communications between drug-sensitive and drug-resistant cells and may transmit both drug efficacy and resistance. Therefore, control of therapeutic response transmission via the bystander effect might offer a promising future cancer treatment. Finally, in tissue regeneration, circulating cells and stromal cells may differentiate into various cells for the purpose of tissue regeneration under direction of the bystander effect arising from surrounding cells in a defective space. We hope that the findings we present will promote the development of innovative cancer therapies and tissue regeneration methodologies from the viewpoint of cell-to-cell interactions through the bystander effect.

A review on targeting tumor microenvironment: The main paradigm shift in the mAb-based immunotherapy of solid tumors

Monoclonal antibodies (mAbs) as biological macromolecules have been remarked the large and growing pipline of the pharmaceutical market and also the most promising tool in modern medicine for cancer therapy. These therapeutic entities, which consist of whole mAbs, armed mAbs (i.e., antibody-toxin conjugates, antibody-drug conjugates, and antibody-radionuclide conjugates), and antibody fragments, mostly target tumor cells. However, due to intrinsic heterogeneity of cancer diseases, tumor cells targeting mAb have been encountered with difficulties in their unpredictable efficacy as well as variability in remission and durable clinical benefits among cancer patients. To address these pitfalls, the area has undergone two major evolutions with the intent of minimizing anti-drug responses and addressing limitations experienced with tumor cell-targeted therapies. As a novel hallmark of cancer, the tumor microenvironment (TME) is becoming the great importance of attention to develop innovative strategies based on therapeutic mAbs. Here, we underscore innovative strategies targeting TME by mAbs which destroy tumor cells indirectly through targeting vasculature system (e.g., anti-angiogenesis), immune system modulation (i.e., stimulation, suppression, and depletion), the targeting and blocking of stroma-based growth signals (e.g., cancer-associated fibroblasts), and targeting cancer stem cells, as well as, their effector mechanisms, clinical uses, and relevant mechanisms of resistance.

The role of extracellular vesicles in the transfer of drug resistance competences to cancer cells

Drug resistance remains a major hurdle to successful cancer treatment, being accountable for approximately 90% of cancer-related deaths. In the past years, increasing attention has been given to the role of extracellular vesicles (EVs) in the horizontal transfer of drug resistance in cancer. Indeed, many studies have described the dissemination of therapy resistance traits mediated by EVs, which may be transferred from drug resistant tumor cells to their drug sensitive counterparts. Importantly, different key players of drug resistance have been identified in the cargo of those EVs, such as drug efflux pumps, oncoproteins, antiapoptotic proteins, or microRNAs, among others. Interestingly, the EVs-mediated crosstalk between cells from the tumor microenvironment (TME) and tumor cells has emerged as another important mechanism that leads to cancer cells drug resistance. Recently, the cargo of the TME-derived EVs responsible for the transfer of drug resistance traits has also become a focus of attention. In addition, the possible mechanisms involved in drug sequestration by EVs, likely to contribute to cancer drug resistance, are also described and discussed herein. Despite the latest scientific advances in the field of EVs, this is still a challenging area of research, particularly in the clinical setting. Therefore, further investigation is needed to assess the relevance of EVs to the failure of cancer patients to drug treatment, to identify biomarkers of drug resistance in the EV's cargo, and to develop effective therapeutic strategies to surmount drug resistance. This up-to-date review summarizes relevant literature on the role of EVs in the transfer of drug resistance competences to cancer cells, and the relevance of tumor cells and of TME cells in this process. Finally, this knowledge is integrated with a discussion of possible future clinical applications of EVs as biomarkers of drug resistance.

Tumor microenvironment manipulates chemoresistance in ovarian cancer (Review)

Ovarian cancer (OC) is the leading cause of mortality among the various types of gynecological cancer, and >75% of the cases are diagnosed at a late stage. Although platinum‑based chemotherapy is able to help the majority of patients to achieve remission, the disease frequently recurs and acquires chemoresistance, resulting in high mortality rates. The complexity of OC therapy is not solely governed by the intrinsic characteristics of the OC cells (OCCs) themselves, but is also largely dependent on the dynamic communication between OCCs and various components of their surrounding microenvironment. The present review attempts to describe the mutual interplay between OCCs and their surrounding microenvironment. Tumor‑associated macrophages (TAMs) and cancer‑associated fibroblasts (CAFs) are the most abundant stromal cell types in OC. Soluble factors derived from CAFs steadily nourish both the OCCs and TAMs, facilitating their proliferation and immune evasion. ATP binding cassette transporters facilitate the extrusion of cytotoxic molecules, eventually promoting cell survival and multidrug resistance. Extracellular vesicles fulfill their role as genetic exchange vectors, transferring cargo from the donor cells to the recipient cells and propagating oncogenic signaling. A greater understanding of the vital roles of the tumor microenvironment will allow researchers to be open to the prospect of developing therapeutic approaches for combating OC chemoresistance.

Fibrous stroma: Driver and passenger in cancer development

Cumulative evidence shows that fibrogenic stroma and stiff extracellular matrix (ECM) not only result from tumor growth but also play pivotal roles in cellular transformation and tumor initiation. This emerging concept may largely account for the increased cancer risk associated with environmental fibrogenic agents, such as asbestos and silica, and with chronic conditions that are fibrogenic, such as obesity and diabetes. It may also contribute to poor outcomes in patients treated with certain chemotherapeutics that can promote fibrosis, such as bleomycin and methotrexate. Although the mechanistic details of this phenomenon are still being unraveled, we provide an overview of the experimental evidence linking fibrogenic stroma and tumor initiation. In this Review, we will summarize the causes and consequences of fibrous stroma and how this stromal cue is transmitted to the nuclei of parenchymal cells through a physical continuum from the ECM to chromatin, as well as ECM-dependent biochemical signaling that contributes to cellular transformation.

Enabling high throughput drug discovery in 3D cell cultures through a novel bioprinting workflow

Advanced three dimensional cell culture techniques have been adopted in many laboratories to better model in vivo tissue by recapitulating multi-cellular architecture and the presence of extracellular matrix features. We describe here a 3D cell culture platform in a small molecule screening workflow that uses traditional biomarker and intracellular kinase end point assay readouts. By combining the high throughput bioprinter RASTRUM with the high throughput screening assay AlphaLISA, we demonstrate the utility of the protocol in 3D synthetic hydrogel cultures with breast cancer (MDA-MB-231 and MCF-7) and fibroblast cells. To establish and validate the workflow, we treated the breast cancer cultures with doxorubicin, while fibroblast cultures were stimulated with the pro-inflammatory lipopolysaccharide. 3D and 2D MDA-MB-231 cultures were equally susceptible to doxorubicin treatment, while showing opposite ERK phosphorylation changes. Doxorubicin readily entered embedded MCF-7 spheroids and markedly reduced intracellular GSK3β phosphorylation. Furthermore, quantifying extracellular interleukin 6 levels showed a very similar activation profile for fibroblasts in 2D and 3D cultures, with 3D fibroblast networks being more resistant against the immune challenge. Through these validation experiments we demonstrate the full compatibility of the bioprinted 3D cell cultures with several widely-used 2D culture assays. The efficiency of the workflow, minimal culture handling, and applicability of traditional screening assays, demonstrates that advanced encapsulated 3D cell cultures can be used in 2D cell culture screening workflows, while providing a more holistic view on cell biology to increase the predictability to in vivo drug response.

Impact of cancer metabolism on therapy resistance - Clinical implications

Despite an increasing arsenal of anticancer therapies, many patients continue to have poor outcomes due to the therapeutic failures and tumor relapses. Indeed, the clinical efficacy of anticancer therapies is markedly limited by intrinsic and/or acquired resistance mechanisms that can occur in any tumor type and with any treatment. Thus, there is an urgent clinical need to implement fundamental changes in the tumor treatment paradigm by the development of new experimental strategies that can help to predict the occurrence of clinical drug resistance and to identify alternative therapeutic options. Apart from mutation-driven resistance mechanisms, tumor microenvironment (TME) conditions generate an intratumoral phenotypic heterogeneity that supports disease progression and dismal outcomes. Tumor cell metabolism is a prototypical example of dynamic, heterogeneous, and adaptive phenotypic trait, resulting from the combination of intrinsic [(epi)genetic changes, tissue of origin and differentiation dependency] and extrinsic (oxygen and nutrient availability, metabolic interactions within the TME) factors, enabling cancer cells to survive, metastasize and develop resistance to anticancer therapies. In this review, we summarize the current knowledge regarding metabolism-based mechanisms conferring adaptive resistance to chemo-, radio-and immunotherapies as well as targeted therapies. Furthermore, we report the role of TME-mediated intratumoral metabolic heterogeneity in therapy resistance and how adaptations in amino acid, glucose, and lipid metabolism support the growth of therapy-resistant cancers and/or cellular subpopulations. We also report the intricate interplay between tumor signaling and metabolic pathways in cancer cells and discuss how manipulating key metabolic enzymes and/or providing dietary changes may help to eradicate relapse-sustaining cancer cells. Finally, in the current era of personalized medicine, we describe the strategies that may be applied to implement metabolic profiling for tumor imaging, biomarker identification, selection of tailored treatments and monitoring therapy response during the clinical management of cancer patients.

Exosomes produced by melanoma cells significantly influence the biological properties of normal and cancer-associated fibroblasts

The incidence of cutaneous malignant melanoma is increasing worldwide. While the treatment of initial stages of the disease is simple, the advanced disease frequently remains fatal despite novel therapeutic options . This requires identification of novel therapeutic targets in melanoma. Similarly to other types of tumours, the cancer microenvironment plays a prominent role and determines the biological properties of melanoma. Importantly, melanoma cell-produced exosomes represent an important tool of intercellular communication within this cancer ecosystem. We have focused on potential differences in the activity of exosomes produced by melanoma cells towards melanoma-associated fibroblasts and normal dermal fibroblasts. Cancer-associated fibroblasts were activated by the melanoma cell-produced exosomes significantly more than their normal counterparts, as assessed by increased transcription of genes for inflammation-supporting cytokines and chemokines, namely IL-6 or IL-8. We have observed that the response is dependent on the duration of the stimulus via exosomes and also on the quantity of exosomes. Our study demonstrates that melanoma-produced exosomes significantly stimulate the tumour-promoting proinflammatory activity of cancer-associated fibroblasts. This may represent a potential new target of oncologic therapy .