Mesenchymal stem cells induce resistance to chemotherapy through the release of platinum-induced fatty acids

The role of host response to chemotherapy: resistance, metastasis and clinical implications

Chemotherapy remains the primary treatment for most metastatic cancers. However, the response to chemotherapy and targeted agents is often transient, and concurrent development of resistance is the primary impediment to effective cancer therapy. Strategies to overcome resistance to treatment have focused on cancer cell intrinsic factors and the tumor microenvironment (TME). Recent evidence indicates that systemic chemotherapy has a significant impact on the host that either facilitates tumor growth, allowing metastatic spread, or renders treatment ineffective. These host responses include the release of bone marrow-derived cells, activation of stromal cells in the TME, and induction of different molecular effectors. Here, we provide an overview of chemotherapy-induced systemic host responses that support tumor aggressiveness and metastasis, and which contribute to therapy resistance. Studying host responses to chemotherapy provides a solid basis for the development of adjuvant strategies to improve treatment outcomes and delay resistance to chemotherapy. This review discusses the emerging field of host response to cancer therapy, and its preclinical and potential clinical implications, explaining how under certain circumstances, these host effects contribute to metastasis and resistance to chemotherapy.

Current and future immunotherapeutic approaches in pancreatic cancer treatment

Pancreatic cancer is a major cause of cancer-related death, but despondently, the outlook and prognosis for this resistant type of tumor have remained grim for a long time. Currently, it is extremely challenging to prevent or detect it early enough for effective treatment because patients rarely exhibit symptoms and there are no reliable indicators for detection. Most patients have advanced or spreading cancer that is difficult to treat, and treatments like chemotherapy and radiotherapy can only slightly prolong their life by a few months. Immunotherapy has revolutionized the treatment of pancreatic cancer, yet its effectiveness is limited by the tumor's immunosuppressive and hard-to-reach microenvironment. First, this article explains the immunosuppressive microenvironment of pancreatic cancer and highlights a wide range of immunotherapy options, including therapies involving oncolytic viruses, modified T cells (T-cell receptor [TCR]-engineered and chimeric antigen receptor [CAR] T-cell therapy), CAR natural killer cell therapy, cytokine-induced killer cells, immune checkpoint inhibitors, immunomodulators, cancer vaccines, and strategies targeting myeloid cells in the context of contemporary knowledge and future trends. Lastly, it discusses the main challenges ahead of pancreatic cancer immunotherapy.

Hepatocellular carcinoma patients serum modulates the regenerative capacities of adipose mesenchymal stromal cells

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers causing the highest mortality rate worldwide. Treatment options of surgery, radiation, cytotoxic drugs and liver transplantation suffer significant side effects and a high frequency of relapse. Stem cell therapy has been proposed as a new effective therapy, however, controversial reports are emerging on the role of mesenchymal stem cells in cancer. In this work, we aimed to assess the regenerative capacities of adipose mesenchymal stem cells when exposed to serum from HCC patients, by assessing the effect of the sera on modulating the regenerative capacities of h-AMSCs and the cancer properties in HCC cells. This will pave the way for maximizing the efficacy of MSCs in cancer therapy. Our data show that HCC serum-treated hA-MSCs suffered oncogene-induced senescence as shown by their altered morphology and ameliorated proliferation and differentiation. The cells were enlarged with small irregular nuclei, swollen rough endoplasmic reticulum cisternae, and aging lysosomes typified by dark residual bodies. HCC serum-treated Huh-7 cancer cells on the other hand displayed higher tumor aggressiveness as depicted by altered morphology, increased cellular proliferation and migration, and decreased percentage of early and late apoptotic cells. Our findings provide evidence that exposure of hA-MSCs to the serum of HCC patients decreases their regenerative capacities and should be considered when employed as a potential therapy in HCC patients.

Bioassay-guided detection, identification and assessment of antibacterial and anti-inflammatory compounds from olive tree flower extracts by high-performance thin-layer chromatography linked to spectroscopy

Olive trees are one of the most widely cultivated fruit trees in the world. The chemical compositions and biological activities of olive tree fruit and leaves have been extensively researched for their nutritional and health-promoting properties. In contrast, limited data have been reported on olive flowers. The present study aimed to analyse bioactive compounds in olive flower extracts and the effect of fermentation-assisted extraction on phenolic content and antioxidant activity. High-performance thin-layer chromatography (HPTLC) hyphenated with the bioassay-guided detection and spectroscopic identification of bioactive compounds was used for the analysis. Enzymatic and bacterial in situ bioassays were used to detect COX-1 enzyme inhibition and antibacterial activity. Multiple zones of antibacterial activity and one zone of COX-1 inhibition were detected in both, non-fermented and fermented, extracts. A newly developed HPTLC-based experimental protocol was used to measure the high-maximal inhibitory concentrations (IC50) for the assessment of the relative potency of the extracts in inhibiting COX-1 enzyme and antibacterial activity. Strong antibacterial activities detected in zones 4 and 7 were significantly higher in comparison to ampicillin, as confirmed by low IC50 values (IC50 = 57-58 µg in zone 4 and IC50 = 157-167 µg in zone 7) compared to the ampicillin IC50 value (IC50 = 495 µg). The COX-1 inhibition by the extract (IC50 = 76-98 µg) was also strong compared to that of salicylic acid (IC50 = 557 µg). By comparing the locations of the bands to coeluted standards, compounds from detected bioactive bands were tentatively identified. The eluates from bioactive HPTLC zones were further analysed by FTIR NMR, and LC-MS spectroscopy. Multiple zones of antibacterial activity were associated with the presence of triterpenoid acids, while COX-1 inhibition was related to the presence of long-chain fatty acids.

LncRNAs-circRNAs as Rising Epigenetic Binary Superstars in Regulating Lipid Metabolic Reprogramming of Cancers

As one of novel hallmarks of cancer, lipid metabolic reprogramming has recently been becoming fascinating and widely studied. Lipid metabolic reprogramming in cancer is shown to support carcinogenesis, progression, distal metastasis, and chemotherapy resistance by generating ATP, biosynthesizing macromolecules, and maintaining appropriate redox status. Notably, increasing evidence confirms that lipid metabolic reprogramming is under the control of dysregulated non-coding RNAs in cancer, especially lncRNAs and circRNAs. This review highlights the present research findings on the aberrantly expressed lncRNAs and circRNAs involved in the lipid metabolic reprogramming of cancer. Emphasis is placed on their regulatory targets in lipid metabolic reprogramming and associated mechanisms, including the clinical relevance in cancer through lipid metabolism modulation. Such insights will be pivotal in identifying new theranostic targets and treatment strategies for cancer patients afflicted with lipid metabolic reprogramming.

Improving targeted small molecule drugs to overcome chemotherapy resistance

BACKGROUND

Conventional cancer treatments face the challenge of therapeutic resistance, which causes poor treatment outcomes. The use of combination therapies can improve treatment results in patients and is one of the solutions to overcome this challenge. Chemotherapy is one of the conventional treatments that, due to the non-targeted and lack of specificity in targeting cancer cells, can cause serious complications in the short and long-term for patients by damaging healthy cells. Also, the employment of a wide range of strategies for chemotherapy resistance by cancer cells, metastasis, and cancer recurrence create serious problems to achieve the desired results of chemotherapy. Accordingly, targeted therapies can be used as a combination treatment with chemotherapy to both cause less damage to healthy cells, which as a result, they reduce the side effects of chemotherapy, and by targeting the factors that cause therapeutic challenges, can improve the results of chemotherapy in patients.

RECENT FINDINGS

Small molecules are one of the main targeted therapies that can be used for diverse targets in cancer treatment due to their penetration ability and characteristics. However, small molecules in cancer treatment are facing obstacles that a better understanding of cancer biology, as well as the mechanisms and factors involved in chemotherapy resistance, can lead to the improvement of this type of major targeted therapy.

CONCLUSION

In this review article, at first, the challenges that lead to not achieving the desired results in chemotherapy and how cancer cells can be resistant to chemotherapy are examined, and at the end, research areas are suggested that more focusing on them, can lead to the improvement of the results of using targeted small molecules as an adjunctive treatment for chemotherapy in the conditions of chemotherapy resistance and metastasis of cancer cells.

Cancer-associated mesenchymal stem/stromal cells: role in progression and potential targets for therapeutic approaches

Malignancies contain a relatively small number of Mesenchymal stem/stromal cells (MSCs), constituting a crucial tumor microenvironment (TME) component. These cells comprise approximately 0.01-5% of the total TME cell population. MSC differentiation potential and their interaction with the tumor environment enable these cells to affect tumor cells' growth, immune evasion, metastasis, drug resistance, and angiogenesis. This type of MSC, known as cancer-associated mesenchymal stem/stromal cells (CA-MSCs (interacts with tumor/non-tumor cells in the TME and affects their function by producing cytokines, chemokines, and various growth factors to facilitate tumor cell migration, survival, proliferation, and tumor progression. Considering that the effect of different cells on each other in the TME is a multi-faceted relationship, it is essential to discover the role of these relationships for targeting in tumor therapy. Due to the immunomodulatory role and the tissue repair characteristic of MSCs, these cells can help tumor growth from different aspects. CA-MSCs indirectly suppress antitumor immune response through several mechanisms, including decreasing dendritic cells (DCs) antigen presentation potential, disrupting natural killer (NK) cell differentiation, inducing immunoinhibitory subsets like tumor-associated macrophages (TAMs) and Treg cells, and immune checkpoint expression to reduce effector T cell antitumor responses. Therefore, if these cells can be targeted for treatment so that their population decreases, we can hope for the treatment and improvement of the tumor conditions. Also, various studies show that CA-MSCs in the TME can affect other vital aspects of a tumor, including cell proliferation, drug resistance, angiogenesis, and tumor cell invasion and metastasis. In this review article, we will discuss in detail some of the mechanisms by which CA-MSCs suppress the innate and adaptive immune systems and other mechanisms related to tumor progression.

Mesenchymal stromal cells confer breast cancer doxorubicin resistance by producing hyaluronan

Chemotherapy resistance represents a major cause of therapeutic failure and mortality in cancer patients. Mesenchymal stromal cells (MSCs), an integral component of tumor microenvironment, are known to promote drug resistance. However, the detailed mechanisms remain to be elucidated. Here, we found that MSCs confer breast cancer resistance to doxorubicin by diminishing its intratumoral accumulation. Hyaluronan (HA), a major extracellular matrix (ECM) product of MSCs, was found to mediate the chemoresistant effect. The chemoresistant effect of MSCs was abrogated when hyaluronic acid synthase 2 (HAS2) was depleted or inhibited. Exogenous HA also protected tumor grafts from doxorubicin. Molecular dynamics simulation analysis indicates that HA can bind with doxorubicin, mainly via hydrophobic and hydrogen bonds, and thus reduce its entry into breast cancer cells. This mechanism is distinct from the reported chemoresistant effect of HA via its receptor on cell surface. High HA serum levels were also found to be positively associated with chemoresistance in breast cancer patients. Our findings indicate that the HA-doxorubicin binding dynamics can confer cancer cells chemoresistance. Reducing HA may enhance chemotherapy efficacy.

Insights into the tumor-stromal-immune cell metabolism cross talk in ovarian cancer

The ovarian cancer tumor microenvironment (TME) consists of a constellation of abundant cellular components, extracellular matrix, and soluble factors. Soluble factors, such as cytokines, chemokines, structural proteins, extracellular vesicles, and metabolites, are critical means of noncontact cellular communication acting as messengers to convey pro- or antitumorigenic signals. Vast advancements have been made in our understanding of how cancer cells adapt their metabolism to meet environmental demands and utilize these adaptations to promote survival, metastasis, and therapeutic resistance. The stromal TME contribution to this metabolic rewiring has been relatively underexplored, particularly in ovarian cancer. Thus, metabolic activity alterations in the TME hold promise for further study and potential therapeutic exploitation. In this review, we focus on the cellular components of the TME with emphasis on 1) metabolic signatures of ovarian cancer; 2) understanding the stromal cell network and their metabolic cross talk with tumor cells; and 3) how stromal and tumor cell metabolites alter intratumoral immune cell metabolism and function. Together, these elements provide insight into the metabolic influence of the TME and emphasize the importance of understanding how metabolic performance drives cancer progression.

The Dual Role of Mesenchymal Stem Cells in Cancer Pathophysiology: Pro-Tumorigenic Effects versus Therapeutic Potential

Mesenchymal stem/stromal cells (MSCs) are multipotent cells involved in numerous physiological events, including organogenesis, the maintenance of tissue homeostasis, regeneration, or tissue repair. MSCs are increasingly recognized as playing a major, dual, and complex role in cancer pathophysiology through their ability to limit or promote tumor progression. Indeed, these cells are known to interact with the tumor microenvironment, modulate the behavior of tumor cells, influence their functions, and promote distant metastasis formation through the secretion of mediators, the regulation of cell-cell interactions, and the modulation of the immune response. This dynamic network can lead to the establishment of immunoprivileged tissue niches or the formation of new tumors through the proliferation/differentiation of MSCs into cancer-associated fibroblasts as well as cancer stem cells. However, MSCs exhibit also therapeutic effects including anti-tumor, anti-proliferative, anti-inflammatory, or anti-oxidative effects. The therapeutic interest in MSCs is currently growing, mainly due to their ability to selectively migrate and penetrate tumor sites, which would make them relevant as vectors for advanced therapies. Therefore, this review aims to provide an overview of the double-edged sword implications of MSCs in tumor processes. The therapeutic potential of MSCs will be reviewed in melanoma and lung cancers.

Targeting ITGB4/SOX2-driven lung cancer stem cells using proteasome inhibitors

This study investigates the role of integrin β4 (ITGB4) and stemness-associated factor SOX2 in platinum resistance in lung squamous cell carcinoma (LUSC). The expression of SOX2 and ITGB4 is found to be high in all LUSC subtypes, but the impact of ITGB4 expression on overall patient survival varies by subtype. Cancer stem cells (CSCs) isolated from LUSC patients were found to be resistant to cisplatin, but knocking down ITGB4 or SOX2 sensitized them to cisplatin. Carfilzomib (CFZ) synergized with cisplatin and suppressed CSC growth by inhibiting ITGB4 and SOX2 expression. Additionally, CFZ was found to inhibit SOX2 expression epigenetically by inhibiting histone acetylation at the SOX2 promoter site. CFZ also suppressed the growth of SOX2-dependent small cell lung cancer cells in vitro and in vivo. The study highlights the unique function of CFZ as a transcriptional suppressor of SOX2, independent of its proteasome inhibitory function.

The covert symphony: cellular and molecular accomplices in breast cancer metastasis

Breast cancer has emerged as the most commonly diagnosed cancer and primary cause of cancer-related deaths among women worldwide. Although significant progress has been made in targeting the primary tumor, the effectiveness of systemic treatments to prevent metastasis remains limited. Metastatic disease continues to be the predominant factor leading to fatality in the majority of breast cancer patients. The existence of a prolonged latency period between initial treatment and eventual recurrence in certain patients indicates that tumors can both adapt to and interact with the systemic environment of the host, facilitating and sustaining the progression of the disease. In order to identify potential therapeutic interventions for metastasis, it will be crucial to gain a comprehensive framework surrounding the mechanisms driving the growth, survival, and spread of tumor cells, as well as their interaction with supporting cells of the microenvironment. This review aims to consolidate recent discoveries concerning critical aspects of breast cancer metastasis, encompassing the intricate network of cells, molecules, and physical factors that contribute to metastasis, as well as the molecular mechanisms governing cancer dormancy.

Mycochemicals against Cancer Stem Cells

Since ancient times, mushrooms have been considered valuable allies of human well-being both from a dietary and medicinal point of view. Their essential role in several traditional medicines is explained today by the discovery of the plethora of biomolecules that have shown proven efficacy for treating various diseases, including cancer. Numerous studies have already been conducted to explore the antitumoural properties of mushroom extracts against cancer. Still, very few have reported the anticancer properties of mushroom polysaccharides and mycochemicals against the specific population of cancer stem cells (CSCs). In this context, β-glucans are relevant in modulating immunological surveillance against this subpopulation of cancer cells within tumours. Small molecules, less studied despite their spread and assortment, could exhibit the same importance. In this review, we discuss several pieces of evidence of the association between β-glucans and small mycochemicals in modulating biological mechanisms which are proven to be involved with CSCs development. Experimental evidence and an in silico approach are evaluated with the hope of contributing to future strategies aimed at the direct study of the action of these mycochemicals on this subpopulation of cancer cells.

MSC-NPRA loop drives fatty acid oxidation to promote stemness and chemoresistance of gastric cancer

Cisplatin (CDDP)-based chemotherapy is the preferred treatment strategy for advanced stage gastric cancer (GC) patients. Despite the efficacy of chemotherapy, the development of chemoresistance negatively affects the prognosis of GC and the underlying mechanism remains poorly understood. Accumulated evidence suggests that mesenchymal stem cells (MSCs) play important roles in drug resistance. The chemoresistance and stemness of GC cells were observed by colony formation, CCK-8, sphere formation and flow cytometry assays. Cell lines and animal models were utilized to investigate related functions. Western blot, quantitative real-time PCR (qRT-PCR) and co-immunoprecipitation were used to explore related pathways. The results showed that MSCs improved the stemness and chemoresistance of GC cells and accounted for the poor prognosis of GC. Natriuretic peptide receptor A (NPRA) was upregulated in GC cells cocultured with MSCs and knockdown of NPRA reversed the MSC-induced stemness and chemoresistance. At the same time, MSCs could be recruited to GC by NPRA, which formed a loop. In addition, NPRA facilitated stemness and chemoresistance through fatty acid oxidation (FAO). Mechanistically, NPRA protected Mfn2 against protein degradation and promoted its mitochondrial localization, which consequently improved FAO. Furthermore, inhibition of FAO with etomoxir (ETX) attenuated MSC-induced CDDP resistance in vivo. In conclusion, MSC-induced NPRA promoted stemness and chemoresistance by upregulating Mfn2 and improving FAO. These findings help us understand the role of NPRA in the prognosis and chemotherapy of GC. NPRA may be a promising target to overcome chemoresistance.

In vitro models of breast cancer bone metastasis: analyzing drug resistance through the lens of the microenvironment

Even though breast cancers usually have a good outcome compared to other tumors, the cancer can progress and create metastases in different parts of the organism, the bone being a predilection locus. These metastases are usually the cause of death, as they are mostly resistant to treatments. This resistance can be caused by intrinsic properties of the tumor, such as its heterogeneity, but it can also be due to the protective role of the microenvironment. By activating signaling pathways protecting cancer cells when exposed to chemotherapy, contributing to their ability to reach dormancy, or even reducing the amount of drug able to reach the metastases, among other mechanisms, the specificities of the bone tissue are being investigated as important players of drug resistance. To this date, most mechanisms of this resistance are yet to be discovered, and many researchers are implementing in vitro models to study the interaction between the tumor cells and their microenvironment. Here, we will review what is known about breast cancer drug resistance in bone metastasis due to the microenvironment and we will use those observations to highlight which features in vitro models should include to properly recapitulate these biological aspects in vitro. We will also detail which elements advanced in vitro models should implement in order to better recapitulate in vivo physiopathology and drug resistance.

The effects of mesenchymal stem cells on the chemotherapy of colorectal cancer

Colorectal cancer (CRC) has been the third commonest cancer in the world. The prognosis of patients with CRC is related to the molecular subtypes and gene mutations, which is prone to recurrence, metastasis, and drug resistance. Mesenchymal stem cells (MSCs) are a group of progenitor ones with the capabilities of self-renewal， multi-directional differentiation, and tissue re-population, which could be isolated from various kinds of tissues and be differentiated into diverse cell types. In recent years, MSCs are applied for mechanisms study of tissue repairing, graft-versus-host disease (GVHD) and autoimmune-related disease, and tumor development, with the advantages of anti-inflammation, multi-lineage differentiation, and homing capability. Integrating the chemotherapy and MSCs therapy might provide a novel treatment approach for CRC patients. In this review, we summarize the current progress in the integrated treatment of integrating the MSCs and chemotherapy for CRC.

The Role of Mesenchymal Stem Cells and Exosomes in Tumor Development and Targeted Antitumor Therapies

Mesenchymal stem cells (MSCs) can be isolated from various tissues in adults and differentiated into cells of the osteoblasts, adipocytes, chondrocytes, and myocytes. Recruitments of MSCs towards tumors have a crucial contribution to tumor development. However, the role of MSCs in the tumor microenvironment is uncertain. In addition, due to its tropism to the tumor and low immunogenic properties, more and more pieces of evidence indicate that MSCs may be an ideal carrier for antitumor biologics such as cytokines, chemotherapeutic agents, and oncolytic viruses. Here, we review the existing knowledge on the anti- and protumorigenic effect of MSCs and their extracellular vesicles and exosomes, the role of MSCs, and their extracellular vesicles and exosomes as antitumor vectors.

Mesenchymal Stromal Cell-Based Targeted Therapy Pancreatic Cancer: Progress and Challenges

Pancreatic cancer is an aggressive malignancy with high mortality rates and poor prognoses. Despite rapid progress in the diagnosis and treatment of pancreatic cancer, the efficacy of current therapeutic strategies remains limited. Hence, better alternative therapeutic options for treating pancreatic cancer need to be urgently explored. Mesenchymal stromal cells (MSCs) have recently received much attention as a potential therapy for pancreatic cancer owing to their tumor-homing properties. However, the specific antitumor effect of MSCs is still controversial. To this end, we aimed to focus on the potential anti-cancer treatment prospects of the MSC-based approach and summarize current challenges in the clinical application of MSCs to treat pancreatic cancer.

Shining the light on mesenchymal stem cell-derived exosomes in breast cancer

In women, breast cancer (BC) is the second most frequently diagnosed cancer and the leading cause of cancer death. Mesenchymal stem cells (MSCs) are a subgroup of heterogeneous non-hematopoietic fibroblast-like cells that have the ability to differentiate into multiple cell types. Recent studies stated that MSCs can migrate into the tumor sites and exert various effect on tumor growth and development. Multiple researches have demonstrated that MSCs can favor tumor growth, while other groups have indicated that MSCs inhibit tumor development. Emerging evidences showed exosomes (Exo) as a new mechanism of cell communication which are essential for the crosstalk between MSCs and BC cells. MSC-derived Exo (MSCs-Exo) could mimic the numerous effects on the proliferation, metastasis, and drug response through carrying a wide scale of molecules, such as proteins, lipids, messenger RNAs, and microRNAs to BC cells. Consequently, in the present literature, we summarized the biogenesis and cargo of Exo and reviewed the role of MSCs-Exo in development of BC.

Cancer Stem Cell Relationship with Pro-Tumoral Inflammatory Microenvironment

Inflammatory processes and cancer stem cells (CSCs) are increasingly recognized as factors in the development of tumors. Emerging evidence indicates that CSCs are associated with cancer properties such as metastasis, treatment resistance, and disease recurrence. However, the precise interaction between CSCs and the immune microenvironment remains unexplored. Although evasion of the immune system by CSCs has been extensively studied, new research demonstrates that CSCs can also control and even profit from the immune response. This review provides an overview of the reciprocal interplay between CSCs and tumor-infiltrating immune cells, collecting pertinent data about how CSCs stimulate leukocyte reprogramming, resulting in pro-tumor immune cells that promote metastasis, chemoresistance, tumorigenicity, and even a rise in the number of CSCs. Tumor-associated macrophages, neutrophils, Th17 and regulatory T cells, mesenchymal stem cells, and cancer-associated fibroblasts, as well as the signaling pathways involved in these pro-tumor activities, are among the immune cells studied. Although cytotoxic leukocytes have the potential to eliminate CSCs, immune evasion mechanisms in CSCs and their clinical implications are also known. We intended to compile experimental findings that provide direct evidence of interactions between CSCs and the immune system and CSCs and the inflammatory milieu. In addition, we aimed to summarize key concepts in order to comprehend the cross-talk between CSCs and the tumor microenvironment as a crucial process for the effective design of anti-CSC therapies.

The interaction between osteosarcoma and other cells in the bone microenvironment: From mechanism to clinical applications

Osteosarcoma is a primary bone tumor with a high mortality rate. The event-free survival rate has not improved significantly in the past 30 years, which brings a heavy burden to patients and society. The high heterogeneity of osteosarcoma leads to the lack of specific targets and poor therapeutic effect. Tumor microenvironment is the focus of current research, and osteosarcoma is closely related to bone microenvironment. Many soluble factors and extracellular matrix secreted by many cells in the bone microenvironment have been shown to affect the occurrence, proliferation, invasion and metastasis of osteosarcoma through a variety of signaling pathways. Therefore, targeting other cells in the bone microenvironment may improve the prognosis of osteosarcoma. The mechanism by which osteosarcoma interacts with other cells in the bone microenvironment has been extensively investigated, but currently developed drugs targeting the bone microenvironment have poor efficacy. Therefore, we review the regulatory effects of major cells and physical and chemical properties in the bone microenvironment on osteosarcoma, focusing on their complex interactions, potential therapeutic strategies and clinical applications, to deepen our understanding of osteosarcoma and the bone microenvironment and provide reference for future treatment. Targeting other cells in the bone microenvironment may provide potential targets for the development of clinical drugs for osteosarcoma and may improve the prognosis of osteosarcoma.

The origins, roles and therapies of cancer associated fibroblast in liver cancer

Hepatocellular carcinoma (HCC) is the most common form of liver cancer. It is often preceded by chronic inflammation such as liver fibrosis and cirrhosis. Different cell types are believed to give rise to liver-specific cancer associated fibroblast (CAF), these include resident fibroblast, hepatic stellate cell, liver cancer cell, hepatic sinusoidal endothelial cell and mesenchymal stromal cell. The abundance of fibroblasts has contributed to the cancer progression, immune modulation and treatment resistance in HCC. In this review, we discussed the origins, subtypes and roles of cancer associated fibroblasts in HCC. Their specific roles in shaping the tumor microenvironment, facilitating cancer growth, and modulating different immune cell types to confer a permissive environment for cancer growth. CAF is now an attractive therapeutic target for cancer treatment, however specific therapeutic development in HCC is still lacking. Hence, we have included preclinical and clinical development of CAF-specific interventions for other cancer types in this review. However, most CAF-specific therapies have resulted in disappointing clinical outcomes, likely due to the difficulties in differentiating CAF from normal fibroblast. A thorough understanding of the characteristics and functionalities of CAF is warranted to further improve the therapeutic efficacy of anti-CAF therapies.

Mesenchymal/stromal stem cells: necessary factors in tumour progression

Mesenchymal/stromal stem cells (MSCs) are a crucial component of the tumour microenvironment (TME). They can be recruited from normal tissues into the TME and educated by tumour cells to transform into tumour-associated MSCs, which are oncogenic cells that promote tumour development and progression by impacting or transforming into various kinds of cells, such as immune cells and endothelial cells. Targeting MSCs in the TME is a novel strategy to prevent malignant processes. Exosomes, as communicators, carry various RNAs and proteins and thus link MSCs and the TME, which provides options for improving outcomes and developing targeted treatment.

The dark side of adipose-derived mesenchymal stromal cells in cutaneous oncology: roles, expectations, and potential pitfalls

Adipose-derived stromal cells (ADSCs) have well-established regenerative and immunomodulatory properties. For such reasons, ADSCs are currently under investigation for their use in the setting of both regenerative medicine and autoimmune diseases. As per dermatological disorders, MSC-based strategies represent potential therapeutic tools not only for chronic ulcers and wound healing, but also for immune-mediated dermatoses. However, a growing body of research has been focusing on the role of MSCs in human cancers, due to the potential oncological risk of using MSC-based strategies linked to their anti-apoptotic, pro-angiogenic and immunosuppressive properties. In the dermatological setting, ADSCs have shown not only to promote melanoma growth and invasiveness, but also to induce drug-resistance. On the other hand, genetically modified ADSCs have been demonstrated to efficiently target therapies at tumor sites, due to their migratory properties and their peculiar tropism for cancer microenvironment. The present review briefly summarizes the findings published so far on the use of ADSCs in the dermato-oncological setting, with the majority of data being available for melanoma.

Mesenchymal Stem/Stromal Cells May Decrease Success of Cancer Treatment by Inducing Resistance to Chemotherapy in Cancer Cells

Simple Summary

Tumours consist of different cell types and an extracellular matrix, all of which together form a complex microenvironment. The tumour microenvironment plays a critical role in various aspects of tumour development and progression. Mesenchymal stem/stromal cells (MSCs) are multipotent stem cells that have a tri-lineage differentiation capacity and are one of the key stromal cells in the tumour microenvironment. Following the interaction with cancer cells, they are transformed from naïve MSCs to tumour-associated MSCs, which substantially affect tumour growth and progression as well as the development of chemoresistance in cancer cells. The aim of this review article is to provide an overview of studies that have investigated how MSCs affect the susceptibility of cancer cells to chemotherapeutics. Their results show that MSCs protect cancer cells from chemotherapeutics by influencing several signalling pathways. This knowledge is crucial for the development of new treatment approaches that will lead to improved treatment outcomes.

Abstract

The tumour microenvironment, which is comprised of various cell types and the extracellular matrix, substantially impacts tumour initiation, progression, and metastasis. Mesenchymal stem/stromal cells (MSCs) are one of the key stromal cells in the tumour microenvironment, and their interaction with cancer cells results in the transformation of naïve MSCs to tumour-associated MSCs. The latter has an important impact on tumour growth and progression. Recently, it has been shown that they can also contribute to the development of chemoresistance in cancer cells. This review provides an overview of 42 studies published between 1 January 2001 and 1 January 2022 that examined the effect of MSCs on the susceptibility of cancer cells to chemotherapeutics. The studies showed that MSCs affect various signalling pathways in cancer cells, leading to protection against chemotherapy-induced damage. Promising results emerged from the use of inhibitors of various signalling pathways that are affected in cancer cells due to interactions with MSCs in the tumour microenvironment. These studies present a good starting point for the investigation of novel treatment approaches and demonstrate the importance of targeting the stroma in the tumour microenvironment to improve treatment outcomes.

Inhibition of CCCTC Binding Factor-Programmed Cell Death Ligand 1 Axis Suppresses Emergence of Chemoresistance Induced by Gastric Cancer-Derived Mesenchymal Stem Cells

Background

Gastric cancer (GC) is the third leading cause of cancer-associated deaths worldwide. Stromal cells, especially mesenchymal stem cells (MSCs), play significant roles in the development of therapy resistance depending on their paracrine function. The PD-1/PD-L1 crosstalk between cancer and immune cells has been well studied. Emerging evidence suggests that PD-L1 also contributes to tumor resistance to therapy.

Methods

Cell survival and apoptosis were assessed using CCK-8, colony formation, and flow cytometry assays. Protein alterations were analyzed via Western blot. Gene knockdown and overexpression were achieved with siRNA/shRNA and lentiviral infection, respectively. Drug effects on tumors in vivo were assessed with xenografts in nude mice. In addition, GC patient samples after chemotherapy treatment were collected to observe the relationship between chemotherapy effect and CTCF or PD-L1.

Results

In response to 5-fluorouracil or paclitaxel treatment, GCMSC-CM enhanced the cell viability and decreased the apoptosis rate. Furthermore, blocking PD-L1 or CTCF in GC cells prevented GCMSC-induced drug resistance accompanied by a decline in cell stemness. Consistent with these in vitro observations, mice treated with GCMSC-CM showed a lower sensitivity to 5-fluorouracil. In addition, high expression of CTCF and PD-L1 was associated with poor chemotherapy progression in the clinic.

Conclusion

Study results demonstrate a mechanism where GCMSC-CM promotes GC chemoresistance by upregulating CTCF-PD-L1 and provide strong evidence in support of targeting CTCF-PD-L1 signaling as a strategy to prevent resistance in the clinic.

The Role of Mesenchymal Stem Cells in the Induction of Cancer-Stem Cell Phenotype

Cancer stem cells (CSCs) modify and form their microenvironment by recruiting and activating specific cell types such as mesenchymal stem cells (MSCs). Tumor-infiltrating MSCs help to establish a suitable tumor microenvironment for the restoration of CSCs and tumor progression. In addition, crosstalk between cancer cells and MSCs in the microenvironment induces a CSC phenotype in cancer cells. Many mechanisms are involved in crosstalk between CSCs/cancer cells and MSCs including cell-cell interaction, secretion of exosomes, and paracrine secretion of several molecules including inflammatory mediators, cytokines, and growth factors. Since this crosstalk may contribute to drug resistance, metastasis, and tumor growth, it is suggested that blockade of the crosstalk between MSCs and CSCs/cancer cells can provide a new avenue to improving the cancer therapeutic tools. In this review, we will discuss the role of MSCs in the induction of cancer stem cell phenotype and the restoration of CSCs. We also discuss targeting the crosstalk between MSCs and CSCs/cancer cells as a therapeutic strategy.

Hepatocellular carcinoma cell line-microenvironment induced cancer-associated phenotype, genotype and functionality in mesenchymal stem cells

Mesenchymal stromal cells (MSCs) have shown promise in liver cancer treatment. However, when MSCs are recruited to hepatic site of injury, they acquire cancerous promoting phenotype.

AIMS

To assess the influence of Hepatocellular carcinoma (HCC) microenvironment on human adipose MSCs (hA-MSCs) and predict hA-MSCs intracellular miRNAs role.

MATERIALS AND METHODS

After indirect co-culturing with Huh-7 cells, hA-MSCs were characterized via cell cycle profile, proliferation and migration potentials by MTT and scratch assays respectively. Functional enrichment analysis of deregulated proteins and miRNA targets was also analyzed.

KEY FINDINGS

Co-cultured hA-MSCs could acquire a cancer-associated phenotype as shown by upregulation of CAF, cancer markers, and downregulation of differentiation markers. Migration of these cancer-associated cells was increased concomitantly with upregulation of adhesion molecules, but not epithelial to mesenchymal transition markers. Co-cultured cells showed increased proliferation confirmed by downregulation in cell percentage in G0/G1, G2/M and upregulation in S phases of cell cycle. Upregulation of miR-17-5p and 615-5p in co-cultured hA-MSCs was also observed. Functional enrichment analysis of dysregulated proteins in co-cultured hA-MSCs, including our selected miRNAs targets, showed their involvement in development of cancer-associated characteristics.

SIGNIFICANCE

This study suggests an interaction between tumor cells and surrounding stromal components to generate cancer associated phenotype of some CAF-like characteristics, known to favor cancer progression. This sheds the light on the use of hA-MSCs in HCC therapy. hA-MSCs modulation may be partially achieved via dysregulation of intracellular miR17-5P and 615-5p expression, suggesting an important role for miRNAs in HCC pathogenesis, and as a possible therapeutic candidate.

Emerging roles of mesenchymal stem cell-derived exosomes in gastrointestinal cancers

Gastrointestinal tumours are the most common solid tumours, with a poor prognosis and remain a major challenge in cancer treatment. Mesenchymal stem cells (MSC) are multipotent stromal cells with the potential to differentiate into multiple cell types. Several studies have shown that MSC-derived exosomes have become essential regulators of intercellular communication in a variety of physiological and pathological processes. Notably, MSC-derived exosomes support or inhibit tumour progression in different cancers through the delivery of proteins, RNA, DNA, and bioactive lipids. Herein, we summarise current advances in MSC-derived exosomes in cancer research, with particular reference to their role in gastrointestinal tumour development. MSC-derived exosomes are expected to be a novel potential strategy for the treatment of gastrointestinal cancers.

Mesenchymal stem cells in cancer progression and anticancer therapeutic resistance

Increasing evidence indicates that the tumor microenvironment appears to play an increasingly important role in cancer progression and therapeutic resistance. Several types of cells within the tumor stroma had distinct impacts on cancer progression, either promoting or inhibiting cancer cell growth. Mesenchymal stem cells (MSCs) are a distinct type of cells that is linked to tumor development. MSCs are recognized for homing to tumor locations and promoting or inhibiting cancer cell proliferation, angiogenesis and metastasis. Moreover, emerging studies suggests that MSCs are also involved in therapeutic resistance. In this review, we analyzed the existing researches and elaborate on the functions of MSCs in cancer progression and anticancer therapeutic resistance, demonstrating that MSCs may be a viable cancer therapeutic target.

Arachidonic acid drives adaptive responses to chemotherapy-induced stress in malignant mesothelioma

Background High resistance to therapy and poor prognosis characterizes malignant pleural mesothelioma (MPM). In fact, the current lines of treatment, based on platinum and pemetrexed, have limited impact on the survival of MPM patients. Adaptive response to therapy-induced stress involves complex rearrangements of the MPM secretome, mediated by the acquisition of a senescence-associated-secretory-phenotype (SASP). This fuels the emergence of chemoresistant cell subpopulations, with specific gene expression traits and protumorigenic features. The SASP-driven rearrangement of MPM secretome takes days to weeks to occur. Thus, we have searched for early mediators of such adaptive process and focused on metabolites differentially released in mesothelioma vs mesothelial cell culture media, after treatment with pemetrexed.

METHODS

Mass spectrometry-based (LC/MS and GC/MS) identification of extracellular metabolites and unbiased statistical analysis were performed on the spent media of mesothelial and mesothelioma cell lines, at steady state and after a pulse with pharmacologically relevant doses of the drug. ELISA based evaluation of arachidonic acid (AA) levels and enzyme inhibition assays were used to explore the role of cPLA2 in AA release and that of LOX/COX-mediated processing of AA. QRT-PCR, flow cytometry analysis of ALDH expressing cells and 3D spheroid growth assays were employed to assess the role of AA at mediating chemoresistance features of MPM. ELISA based detection of p65 and IkBalpha were used to interrogate the NFkB pathway activation in AA-treated cells.

RESULTS

We first validated what is known or expected from the mechanism of action of the antifolate. Further, we found increased levels of PUFAs and, more specifically, arachidonic acid (AA), in the transformed cell lines treated with pemetrexed. We showed that pharmacologically relevant doses of AA tightly recapitulated the rearrangement of cell subpopulations and the gene expression changes happening in pemetrexed -treated cultures and related to chemoresistance. Further, we showed that release of AA following pemetrexed treatment was due to cPLA2 and that AA signaling impinged on NFkB activation and largely affected anchorage-independent, 3D growth and the resistance of the MPM 3D cultures to the drug.

CONCLUSIONS

AA is an early mediator of the adaptive response to pem in chemoresistant MPM and, possibly, other malignancies.

Mesenchymal Stem Cells and Extracellular Vesicles in Osteosarcoma Pathogenesis and Therapy

Osteosarcoma (OS) is an aggressive bone tumor that mainly affects children and adolescents. OS has a strong tendency to relapse and metastasize, resulting in poor prognosis and survival. The high heterogeneity and genetic complexity of OS make it challenging to identify new therapeutic targets. Mesenchymal stem cells (MSCs) are multipotent stem cells that can differentiate into adipocytes, osteoblasts, or chondroblasts. OS is thought to originate at some stage in the differentiation process of MSC to pre-osteoblast or from osteoblast precursors. MSCs contribute to OS progression by interacting with tumor cells via paracrine signaling and affect tumor cell proliferation, invasion, angiogenesis, immune response, and metastasis. Extracellular vesicles (EVs), secreted by OS cells and MSCs in the tumor microenvironment, are crucial mediators of intercellular communication, driving OS progression by transferring miRNAs/RNA and proteins to other cells. MSC-derived EVs have both pro-tumor and anti-tumor effects on OS progression. MSC-EVs can be also engineered to deliver anti-tumor cargo to the tumor site, which offers potential applications in MSC-EV-based OS treatment. In this review, we highlight the role of MSCs in OS, with a focus on EV-mediated communication between OS cells and MSCs and their role in OS pathogenesis and therapy.

LncRNA SNHG7 Regulates Mesenchymal Stem Cell Through the Notch1/Jagged1/Hes-1 Signaling Pathway and Influences Folfirinox Resistance in Pancreatic Cancer

Pancreatic cancer (PC) is one of the deadliest gastrointestinal cancers, accounting for the fourth highest number of cancer-related fatalities. Increasing data suggests that mesenchymal stem cells (MSCs) might influence the drug resistance of GC cells in the tumor microenvironment and play essential roles in drug resistance development. However, the precise underlying process remains a mystery. The purpose of this study was to look at the control of MSC-induced SNHG7 in pancreatic cancer. In vitro and in vivo sphere formation, colony formation, and flow cytometry investigations revealed the stemness and Folfirinox resistance in pancreatic cancer cells. To confirm the direct connections between SNHG7 and other related targets, RNA pulldown and immunoprecipitation tests were performed. MSC co-culture enhanced the stemness and Folfirinox resistance in pancreatic cancer cells according to the findings. MSC co-culture increased SNHG7 expression in pancreatic cancer cells, contributing to the stemness and Folfirinox resistance. We demonstrated that Notch1 interacted with SNHG7 and could reverse the facilitative effect of SNHG7 on the stemness and Folfirinox resistance in pancreatic cancer cells. Finally, our findings showed that MSCs increased SNHG7 expression in pancreatic cancer cells, promoting the stemness and Folfirinox resistance via the Notch1/Jagged1/Hes-1 signaling pathway. These findings could provide a novel approach and therapeutic target for pancreatic cancer patients.

Lignans from Bursera fagaroides: Chemistry, Pharmacological Effects and Molecular Mechanism. A Current Review

Bursera fagaroides is a medicinal tree endemic to México, it belongs to the Burseraceae family and has proven antitumor activity. Modern research, performed principally with the bark extracts, have indicated that lignans are the main active constituents of B. fagaroides, with a high content of aryltetralin, aryldihydronaphtalene, dibenzylbutirolactone, and dibenzylbutane-type lignans as the constituents of the active extracts. In general, lignans from B. fagaroides exhibited potent anti-cancer activity, although antitumor, anti-bacterial, anti-protozoal, anti-inflammatory, and anti-viral properties have also been described. This review covers literature-reported lignans from B. fagaroides, chemical structures, nomenclature, chromatographic techniques of isolation, characterization strategies, and highlights the anti-cancer molecular mechanisms of lignans. Evaluation of the anticancer function of lignans has been extensively investigated since the cytotoxic in vitro results and in vivo assays in mice and zebrafish models to the tubulin molecular recognition by NMR. Also, we discuss the future direction for studying this important plant species and its lignan metabolites.

CD90low glioma-associated mesenchymal stromal/stem cells promote temozolomide resistance by activating FOXS1-mediated epithelial-mesenchymal transition in glioma cells

Background

The tumour microenvironment contributes to chemotherapy resistance in gliomas, and glioma-associated mesenchymal stromal/stem cells (gaMSCs) are important stromal cell components that play multiple roles in tumour progression. However, whether gaMSCs affect chemotherapy resistance to the first-line agent temozolomide (TMZ) remains unclear. Herein, we explored the effect and mechanism of gaMSCs on resistance to TMZ in glioma cells.

Methods

Human glioma cells (cell line U87MG and primary glioblastoma cell line GBM-1) were cultured in conditioned media of gaMSCs and further treated with TMZ. The proliferation, apoptosis and migration of glioma cells were detected by Cell Counting Kit-8 (CCK-8), flow cytometry and wound-healing assays. The expression of FOXS1 in glioma cells was analysed by gene microarray, PCR and Western blotting. Then, FOXS1 expression in glioma cells was up- and downregulated by lentivirus transfection, and markers of the epithelial-mesenchymal transformation (EMT) process were detected. Tumour-bearing nude mice were established with different glioma cells and treated with TMZ to measure tumour size, survival time and Ki-67 expression. Finally, the expression of IL-6 in gaMSC subpopulations and its effects on FOXS1 expression in glioma cells were also investigated.

Results

Conditioned media of gaMSCs promoted the proliferation, migration and chemotherapy resistance of glioma cells. The increased expression of FOXS1 and activation of the EMT process in glioma cells under gaMSC-conditioned media were detected. The relationship of FOXS1, EMT and chemotherapy resistance in glioma cells was demonstrated through the regulation of FOXS1 expression in vitro and in vivo. Moreover, FOXS1 expression in glioma cells was increased by secretion of IL-6 mainly from the CD90^low gaMSC subpopulation.

Conclusions

CD90^low gaMSCs could increase FOXS1 expression in glioma cells by IL-6 secretion, thereby activating epithelial-mesenchymal transition and resistance to TMZ in glioma cells. These results indicate a new role of gaMSCs in chemotherapy resistance and provide novel therapeutic targets.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02458-8.

Importance of the origin of mesenchymal (stem) stromal cells in cancer biology: "alliance" or "war" in intercellular signals

Mesenchymal stem cells (MSCs) play a central role in the intercellular signaling within the tumor microenvironment (TME), exchanging signals with cancer cells and tumor stromal cells, such as cancer-associated fibroblasts and inflammatory mononuclear cells. Research attributes both pro-tumor and anti-tumor actions to MSCs; however, evidence indicates that MSCs specific effect on the tumor depends on the source of the MSCs and the type of tumor. There are consistent data proving that MSCs from reproductive tissues, such as the uterus, umbilical cord or placenta, have potent anti-tumor effects and tropism towards tumor tissues. More interestingly, products derived from MSCs, such as secretome or extracellular vesicles, seem to reproduce the effects of their parental cells, showing a potential advantage for clinical treatments by avoiding the drawbacks associated with cell therapy. Given these perspectives, it appears necessary new research to optimize the production, safety and antitumor potency of the products derived from the MSCs suitable for oncological therapies.

Specialized nutrition improves muscle function and physical activity without affecting chemotherapy efficacy in C26 tumour-bearing mice

BACKGROUND

Skeletal muscle wasting and fatigue are commonly observed in cancer patients receiving chemotherapy and associated with reduced treatment outcome and quality of life. Nutritional support may mitigate these side effects, but potential interference with chemotherapy efficacy could be of concern. Here, we investigated the effects of an ω-3 polyunsaturated fatty acid (eicosapentaenoic acid and docosahexaenoic acid), leucine-enriched, high-protein (100% whey), additional vitamin D, and prebiotic fibres 'specific nutritional composition' (SNC) and chemotherapy on state-of-the-art tumour organoids and muscle cells and studied muscle function, physical activity, systemic inflammation, and chemotherapy efficacy in a mouse model of aggressive colorectal cancer (CRC).

METHODS

Tumour-bearing mice received a diet with or without SNC. Chemotherapy treatment consisted of oxaliplatin and 5-fluorouracil. Tumour formation was monitored by calliper measurements. Physical activity was continuously monitored by infrared imaging. Ex vivo muscle performance was determined by myography, muscle fatty acid composition by gas chromatography, and plasma cytokine levels by Luminex xMAP technology. Patient-derived CRC organoids and C2C12 myotubes were used to determine whether SNC affects chemotherapy sensitivity in vitro.

RESULTS

Specific nutritional composition increased muscle contraction capacity of chemotherapy-treated tumour-bearing mice (P < 0.05) and enriched ω-3 fatty acid composition in muscle without affecting treatment efficacy (P < 0.0001). Mice receiving SNC maintained physical activity after chemotherapy and showed decreased systemic inflammation. Therapeutic response of CRC organoids was unaffected by SNC nutrients, while cell viability and protein synthesis of muscle cells significantly improved.

CONCLUSIONS

The results show that specialized nutritional support can be used to maintain muscle function and physical activity levels during chemotherapy without increasing tumour viability. Therefore, nutritional strategies have potential value in promoting cancer and chemotherapy tolerance.

Silencing of LRRFIP1 enhances the sensitivity of gemcitabine in pancreatic cancer cells by activating JNK/c-Jun signaling

BACKGROUND

The epithelial-mesenchymal transition (EMT) in cancer cells has been shown to closely associate with the survival and drug resistance of cancer cells. We recently provided evidence that Wnt signal activator leucine-rich repeat in flightless-1-interacting protein 1 (LRRFIP1) regulates EMT in pancreatic cancer. LRRFIP1 silencing inhibits the translocation of β-catenin to the nucleus, which led to reverse EMT in cancer cells. It was suggested that LRRFIP1 was implicated in gemcitabine sensitivity by regulating EMT signaling.

METHODS

Gemcitabine chemosensitivity was investigated in LRRFIP1-knockdown pancreatic cancer cells (PANC-1 and MIA Paca-2). In addition, the effects of LRRFIP1 knockdown on JNK/SAPK (stress activated-protein kinase) signaling and apoptosis were evaluated.

RESULTS

LRRFIP1 silencing accelerates gemcitabine-induced caspase activity and cell death in pancreatic cancer cells. It was also revealed that gemcitabine-induced phosphorylation of c-Jun N-terminal kinase (JNK) and c-Jun were increased in LRRFIP1 knockdown cells. The activation of JNK/c-Jun in LRRFIP1-knockdown cells was significantly diminished by the inhibition of Rac activity. It was confirmed that the acquisition of gemcitabine sensitivity by LRRFIP1 silencing largely depends on the stimulation of JNK/SAPK (stress activated-protein kinase) signaling.

CONCLUSIONS

Our findings suggest that reversing EMT and transient activation of JNK might be essential for the gemcitabine sensitivity in LRRFIP1 knockdown pancreatic cancer cells. Our discoveries highlight the potential role of LRRFIP1 in the chemosensitivity related to the regulation of EMT signaling.

The Role of Tumor-Stroma Interactions in Drug Resistance Within Tumor Microenvironment

Cancer cells resistance to various therapies remains to be a key challenge nowadays. For a long time, scientists focused on tumor cells themselves for the mechanisms of acquired drug resistance. However, recent evidence showed that tumor microenvironment (TME) is essential for regulating immune escape, drug resistance, progression and metastasis of malignant cells. Reciprocal interactions between cancer cells and non-malignant cells within this milieu often reshape the TME and promote drug resistance. Therefore, advanced knowledge about these sophisticated interactions is significant for the design of effective therapeutic approaches. In this review, we highlight cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs), T-regulatory lymphocytes (Tregs), mesenchymal stem cells (MSCs), cancer-associated adipocytes (CAAs), and tumor endothelial cells (TECs) existing in TME, as well as their multiple cross-talk with tumor cells, which eventually endows tumor cells with therapeutic resistance.

Effect of 6,9,12,15-Hexadecatetraenoic Acid (C16:4n-1)-Ethyl Ester on Lipid Content and Fatty Acid Composition in the Blood and Organs of Mice

The effects of 6,9,12,15-hexadecatetraenoic acid (C16:4n-1, HDTA), an n-1 polyunsaturated fatty acid (FA), on plasma and liver lipid content and distribution in blood and tissues were investigated. Mice were fed experimental diets containing 10% HDTA or eicosapentaenoic acid in ethyl ester form based on corn oil for four weeks. Dietary HDTA intake lowered plasma triacylglycerol content without affecting plasma total cholesterol content. HDTA barely accumulated in the epididymal white adipose tissue (eWAT), while C18:4n-1, an HDTA metabolite, was detected in small amounts (< 1% of total FAs) in the plasma, liver, and eWAT.

Enhanced expression of cyclooxygenase-2 related multi-drug resistance gene in melanoma and osteosarcoma cell lines by TSG-6 secreted from canine adipose-derived mesenchymal stem/stromal cells

BACKGROUND

Multiple drug resistance (MDR) of cancer cells is the main cause of intrinsic or acquired desensitization to chemotherapy in many cancers. A number of studies have found high expression of COX-2 to be a factor for expression of MDR gene in several cancer. Furthermore, adipose tissue derived mesenchymal stem/stromal cells (ADSC) have been found to increase cyclo-oxygenase-2 (COX-2) expression in some tumour cells. The mechanism for this, however, is not yet clear and needs further study.

OBJECTIVE

The purpose of this study was to determine whether tumour necrosis factor-alpha stimulated gene/protein 6 (TSG-6) secreted from ADSCs is associated with an increase in MDR genes by inducing COX-2 gene expression in melanoma and osteosarcoma cell lines.

METHODS

ADSCs were transfected with TSG-6 siRNA or Control RNA respected, and cancer cell line were transfected with COX-2 siRNA or Control RNA respected. Using trans well coculture system, the interactions of ADSCs with tumour cells were investigated.

RESULTS

Increased COX-2 expression was observed in cancer cell co-cultured with ADSCs. Additionally, we identified that COX-2 expression was related to drug resistance genes (P-glycoprotein, multidrug resistance-associated protein). Transfecting canine ADSCs with small interfering RNA, TSG-6 secreted from ADSCs was found to be a major factor in the regulation of COX-2 expression and drug resistance genes in osteosarcoma and melanoma cell lines.

CONCLUSION

TSG-6 mediated COX-2 up-regulation is a possible mechanism of chemoresistance development induced by ADSCs. These findings provide better understanding about the mechanism associated with ADSC-induced chemoresistance in cancer.

Synthesis, Inhibitory Activity, and In Silico Modeling of Selective COX-1 Inhibitors with a Quinazoline Core

Selective cyclooxygenase-1 (COX-1) inhibition has got into the spotlight with the discovery of COX-1 upregulation in various cancers and the cardioprotective role of COX-1 in control of thrombocyte aggregation. Yet, COX-1-selective inhibitors are poorly explored. Thus, three series of quinazoline derivatives were prepared and tested for their potential inhibitory activity toward COX-1 and COX-2. Of the prepared compounds, 11 exhibited interesting COX-1 selectivity, with 8 compounds being totally COX-1-selective. The IC50 value of the best quinazoline inhibitor was 64 nM. The structural features ensuring COX-1 selectivity were elucidated using in silico modeling.

In-Depth Characterization of Stromal Cells within the Tumor Microenvironment Yields Novel Therapeutic Targets

Simple Summary

This up-to-date and in-depth review describes fibroblast-derived cells and their role within the tumor microenvironment for tumor progression. Moreover, targets for future antitumor therapies are summarized and potential aspects for future translational research are outlined. Furthermore, this review discusses the challenges and possible obstacles related to certain treatment targets.

Abstract

Cells within the tumor stroma are essential for tumor progression. In particular, cancer-associated fibroblasts (CAF) and CAF precursor cells (resident fibroblasts and mesenchymal stromal cells) are responsible for the formation of the extracellular matrix in tumor tissue. Consequently, CAFs directly and indirectly mediate inflammation, metastasis, immunomodulation, angiogenesis, and the development of tumor chemoresistance, which is orchestrated by complex intercellular cytokine-mediated crosstalk. CAFs represent a strategic target in antitumor therapy but their heterogeneity hinders effective treatment regimes. In-depth understanding of CAF subpopulations and knowledge of specific functions in tumor progression will ultimately result in more specific and effective cancer treatments. This review provides a detailed description of CAFs and CAF precursor cells and summarizes possible treatment strategies as well as molecular targets of these cells in antitumor therapies.

DCBLD2 Mediates Epithelial-Mesenchymal Transition-Induced Metastasis by Cisplatin in Lung Adenocarcinoma

Growing evidence suggests that cisplatin and other chemotherapeutic agents promote tumor metastasis while inhibiting tumor growth, which is a critical issue for certain patients in clinical practices. However, the role of chemotherapeutics in promoting tumor metastasis and the molecular mechanism involved are unclear. Here, we investigated the roles of cisplatin in promoting tumor metastasis in lung adenocarcinoma (LUAD). We demonstrated that cisplatin promoted epithelial-mesenchymal transition (EMT), cell motility, and metastasis in vitro and in vivo. The bioinformatic analysis and molecular biology approaches also indicated that DCBLD2 (Discoidin, CUB and LCCL domain containing 2) is a key gene that mediates cisplatin-induced metastasis. DCBLD2 stabilizes β-catenin by phosphorylating GSK3β and transporting accumulated β-catenin to the nucleus to promote the expression of EMT-related transcriptional factors (TFs), ultimately resulting in tumor metastasis. We also identified that cisplatin enhanced DCBLD2 expression by phosphorylating ERK and hence the AP-1-driven transcription of DCBLD2. Furthermore, DCBLD2-specific siRNAs encapsulated by nanocarriers prominently inhibit cisplatin-induced metastasis in vivo. Therefore, DCBLD2 plays a key role in cisplatin-induced metastasis in LUAD and is a potential target for preventing chemotherapy-induced metastasis in vivo.

Targeting stromal cell Syndecan-2 reduces breast tumour growth, metastasis and limits immune evasion

Tumour stromal cells support tumourigenesis. We report that Syndecan-2 (SDC2) is expressed on a nonepithelial, nonhaematopoietic, nonendothelial stromal cell population within breast cancer tissue. In vitro, syndecan-2 modulated TGFβ signalling (SMAD7, PAI-1), migration and immunosuppression of patient-derived tumour-associated stromal cells (TASCs). In an orthotopic immunocompromised breast cancer model, overexpression of syndecan-2 in TASCs significantly enhanced TGFβ signalling (SMAD7, PAI-1), tumour growth and metastasis, whereas reducing levels of SDC2 in TASCs attenuated TGFβ signalling (SMAD7, PAI-1, CXCR4), tumour growth and metastasis. To explore the potential for therapeutic application, a syndecan-2-peptide was generated that inhibited the migratory and immunosuppressive properties of TASCs in association with reduced expression of TGFβ-regulated immunosuppressive genes, such as CXCR4 and PD-L1. Moreover, using an orthotopic syngeneic breast cancer model, overexpression of syndecan-2-peptide in TASCs reduced tumour growth and immunosuppression within the TME. These data provide evidence that targeting stromal syndecan-2 within the TME inhibits tumour growth and metastasis due to decreased TGFβ signalling and increased immune control.

Changes in the extracellular microenvironment and osteogenic responses of mesenchymal stem/stromal cells induced by in vitro direct electrical stimulation

Electrical stimulation (ES) has potential to be an effective tool for bone injury treatment in clinics. However, the therapeutic mechanism associated with ES is still being discussed. This study aims to investigate the initial mechanism of action by characterising the physical and chemical changes in the extracellular environment during ES and correlate them with the responses of mesenchymal stem/stromal cells (MSCs). Computational modelling was used to estimate the electrical potentials relative to the cathode and the current density across the cell monolayer. We showed expression of phosphorylated ERK1/2, c-FOS, c-JUN, and SPP1 mRNAs, as well as the increased metabolic activities of MSCs at different time points. Moreover, the average of 2.5 μM of H₂O₂ and 34 μg/L of dissolved Pt were measured from the electrically stimulated media (ES media), which also corresponded with the increases in SPP1 mRNA expression and cell metabolic activities. The addition of sodium pyruvate to the ES media as an antioxidant did not alter the SPP1 mRNA expression, but eliminated an increase in cell metabolic activities induced by ES media treatment. These findings suggest that H₂O₂ was influencing cell metabolic activity, whereas SPP1 mRNA expression was regulated by other faradic by-products. This study reveals how different electrical stimulation regime alters cellular regenerative responses and the roles of faradic by-products, that might be used as a physical tool to guide and control cell behaviour.

Tumor-Associated Macrophages Promote Oxaliplatin Resistance via METTL3-Mediated m6A of TRAF5 and Necroptosis in Colorectal Cancer

As a third-generation platinum drug, oxaliplatin (OX) is widely used as the first-line chemotherapeutic agent in the treatment of colorectal cancer (CRC). CRC cells acquire resistance to chemotherapy and develop resistance, which is a major challenge for the treatment of advanced CRC. Recent studies have suggested that the therapeutic resistance of tumors is affected by the tumor microenvironment (TME). As a critical role among TME, tumor-associated macrophages (TAMs) play an important role. However, their regulatory mechanism underlying the drug resistance in CRC remains largely unknown. In the present study, we found that the density of macrophages infiltrated into the CRC tissues from OX-resistant patients was significantly higher compared with the OX-sensitive patients. Interestingly, both the total N⁶-methyladenosine (m⁶A) RNA content and the expression of its critical methyltransferase METTL3 were increased in the CRC tissues from OX-resistant patients compared with the OX-sensitive patients. Furthermore, we demonstrated that the M2-polarized TAMs enabled the OX resistance via the elevation of METTL3-mediated m⁶A modification in cells. Through whole-genome CRISPR screening and further validation, we found that TRAF5 contributes to the METTL3-triggered OX resistance in CRC cells. This study unveiled that M2-TAMs were important mediators for the acquisition of OX resistance. Furthermore, we provided evidence that targeting of M2-TAMs and METTL3-mediated m⁶A modification might be a promising adjuvant therapeutic strategy for CRC patients, especially for OX-resistant CRC patients.

The Role of BRCA1/2-Mutated Tumor Microenvironment in Breast Cancer

Taking into account the factors of high incidence rate, prevalence and mortality, breast cancer represents a crucial social and economic burden. Most cases of breast cancer develop as a consequence of somatic mutations accumulating in mammary epithelial cells throughout lifetime and approximately 5-10% can be ascribed to monogenic predispositions. Even though the role of genetic predispositions in breast cancer is well described in the context of genetics, very little is known about the role of the microenvironment carrying the same aberrant cells impaired by the germline mutation in the breast cancer development and progression. Based on the clinical observations, carcinomas carrying mutations in hereditary tumor-suppressor genes involved in maintaining genome integrity such as BRCA1/2 have worse prognosis and aggressive behavior. One of the mechanisms clarifying the aggressive nature of BRCA-associated tumors implies alterations within the surrounding adipose tissue itself. The objective of this review is to look at the role of BRCA1/2 mutations in the context of breast tumor microenvironment and plausible mechanisms by which it contributes to the aggressive behavior of the tumor cells.

Metabolism and biological functions of 12(S)-hydroxyheptadeca-5Z,8E,10E-trienoic acid

12(S)-hydroxyheptadeca-5Z,8E,10E-trienoic acid (12-HHT) is a 17-carbon hydroxy fatty acid that is biosynthesized either by enzymatic pathways, like thromboxane synthase (TXAS) and cytochrome P450 or a non-enzymatic pathway. TXAS catalyzes the isomerization reaction from PGH2 to 12-HHT, malondialdehyde, and TXA2 at a ratio of 1:1:1. Furthermore, 12-HHT has been considered as a mere byproduct of TXA2 biosynthesis, and its biological function has long been uncertain. BLT2 was initially identified as a low-affinity leukotriene B4 (LTB4) receptor, which is also activated by various hydroxy-eicosatetraenoic acids (HETEs), suggesting that BLT2 may be activated by other endogenous ligands apart from LTB4 and HETEs. By unbiased ligand screening using crude lipids from rat organs, 12-HHT has been identified as an endogenous agonist for BLT2. The 12-HHT-BLT2 axis induces mast cell migration and contributes to allergic inflammation. BLT2 is also expressed in epithelial cells of the small intestine and skin in mice and contributes to in vivo epithelial barrier functions.

The CXCL12 Crossroads in Cancer Stem Cells and Their Niche

Simple Summary

CXCL12 and its receptors have been extensively studied in cancer, including their influence on cancer stem cells (CSCs) and their niche. This intensive research has led to a better understanding of the crosstalk between CXCL12 and CSCs, which has aided in designing several drugs that are currently being tested in clinical trials. However, a comprehensive review has not been published to date. The aim of this review is to provide an overview on how CXCL12 axes are involved in the regulation and maintenance of CSCs, their presence and influence at different cellular levels within the CSC niche, and the current state-of-the-art of therapeutic approaches aimed to target the CXCL12 crossroads.

Abstract

Cancer stem cells (CSCs) are defined as a subpopulation of “stem”-like cells within the tumor with unique characteristics that allow them to maintain tumor growth, escape standard anti-tumor therapies and drive subsequent repopulation of the tumor. This is the result of their intrinsic “stem”-like features and the strong driving influence of the CSC niche, a subcompartment within the tumor microenvironment that includes a diverse group of cells focused on maintaining and supporting the CSC. CXCL12 is a chemokine that plays a crucial role in hematopoietic stem cell support and has been extensively reported to be involved in several cancer-related processes. In this review, we will provide the latest evidence about the interactions between CSC niche-derived CXCL12 and its receptors—CXCR4 and CXCR7—present on CSC populations across different tumor entities. The interactions facilitated by CXCL12/CXCR4/CXCR7 axes seem to be strongly linked to CSC “stem”-like features, tumor progression, and metastasis promotion. Altogether, this suggests a role for CXCL12 and its receptors in the maintenance of CSCs and the components of their niche. Moreover, we will also provide an update of the therapeutic options being currently tested to disrupt the CXCL12 axes in order to target, directly or indirectly, the CSC subpopulation.