Wnt/IL-1β/IL-8 autocrine circuitries control chemoresistance in mesothelioma initiating cells by inducing ABCB5

Huaier suppresses cisplatin resistance in non-small cell lung cancer by inhibiting the JNK/JUN/IL-8 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Huaier (Trametes robiniophila Murr), a traditional Chinese medicinal fungus, possesses potent anticancer efficacy and has been used as an adjuvant medication for liver, breast, gastric, intestinal, and non-small cell lung cancer (NSCLC). However, the potential regulatory functions and underlying molecular mechanisms of Huaier in cisplatin resistance of NSCLC remain unknown.

AIM

To evaluate the potential regulatory functions and underlying molecular mechanisms of Huaier in cisplatin resistance of NSCLC.

MATERIALS AND METHODS

In vitro and in vivo experiments were employed to evaluate the regulatory functions of Huaier in cisplatin-resistant NSCLC cells. Transcriptome sequencing and validation analyses was undertaken to identify the downstream targets of Huaier. Network pharmacology, ultra-performance liquid chromatography-mass spectroscopy, and in vitro and in vivo experiments were performed to identify key small molecule drug candidates in Huaier and the regulatory mechanisms these employ to suppress cisplatin resistance in NSCLC.

RESULTS

Huaier suppressed cisplatin resistance and cancer cell stemness in cisplatin-resistant NSCLC cells, both in vitro and in vivo. Mechanistically, Huaier could suppress expression of interleuken-8 (IL-8) through inhibition of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and activator protein-1 (AP-1), two key transcription factors responsible for the activation of IL-8 transcription. Kaempferol was identified as one of the key small molecule compounds in Huaier that could suppress cisplatin resistance by inhibiting the phosphorylation and nuclear translocation of proto-oncogene c-Jun (JUN) by binding and inhibiting the kinase activity of c-Jun N-terminal protein kinase (JNK).

CONCLUSIONS

Huaier suppressed cisplatin resistance of NSCLC cells by inhibiting the JNK/JUN/IL-8 signaling pathway.

IL-1β is involved in docetaxel chemoresistance by regulating the formation of polyploid giant cancer cells in non-small cell lung cancer

Docetaxel (Doc) is a cornerstone of chemotherapy; however, treatment with Doc often and inevitably leads to drug resistance and the formation of polyploid giant cancer cells (PGCCs). In this study, we investigated the effect of Doc on non-small cell lung cancer to explore the role of PGCCs in drug resistance and the molecular mechanisms that regulate this resistance. We found that Doc induced G2/M cell cycle arrest and cell death in A549 and NCI-H1299 cells. However, many cells remained alive and became PGCCs by decreasing the expression of key regulatory proteins related to the cell cycle and proliferation. Notably, the PGCCs showed typical features of senescence, especially upregulation of p21 and p-histone H2A.X expression. Moreover, the mRNA level of IL-1β in the senescence-associated secretory phenotype was increased significantly with the development of PGCCs. Inhibition of IL-1β reduced the expression of p-histone H2A.X and promoted polyploidy to enhance the proapoptotic effect of Doc. Taken together, our results suggested that IL-1β was involved in the formation of PGCCs and regulated the senescence of PGCCs, which contributed to drug resistance to Doc. Therefore, targeting IL-1β in PGCCs may be a novel approach to overcome drug resistance.

ABC transporters affects tumor immune microenvironment to regulate cancer immunotherapy and multidrug resistance

Multidrug resistance (MDR) is the phenomenon in which cancer cells simultaneously develop resistance to a broad spectrum of structurally and mechanistically unrelated drugs. MDR severely hinders the effective treatment of cancer and is the major cause of chemotherapy failure. ATP-binding cassette (ABC) transporters are extensively expressed in various body tissues, and actively transport endogenous and exogenous substrates through biological membranes. Overexpression of ABC transporters is frequently observed in MDR cancer cells, which promotes efflux of chemotherapeutic drugs and reduces their intracellular accumulation. Increasing evidence suggests that ABC transporters regulate tumor immune microenvironment (TIME) by transporting various cytokines, thus controlling anti-tumor immunity and sensitivity to anticancer drugs. On the other hand, the expression of various ABC transporters is regulated by cytokines and other immune signaling molecules. Targeted inhibition of ABC transporter expression or function can enhance the efficacy of immune checkpoint inhibitors by promoting anticancer immune microenvironment. This review provides an update on the recent research progress in this field.

DRESIS: the first comprehensive landscape of drug resistance information

Widespread drug resistance has become the key issue in global healthcare. Extensive efforts have been made to reveal not only diverse diseases experiencing drug resistance, but also the six distinct types of molecular mechanisms underlying this resistance. A database that describes a comprehensive list of diseases with drug resistance (not just cancers/infections) and all types of resistance mechanisms is now urgently needed. However, no such database has been available to date. In this study, a comprehensive database describing drug resistance information named 'DRESIS' was therefore developed. It was introduced to (i) systematically provide, for the first time, all existing types of molecular mechanisms underlying drug resistance, (ii) extensively cover the widest range of diseases among all existing databases and (iii) explicitly describe the clinically/experimentally verified resistance data for the largest number of drugs. Since drug resistance has become an ever-increasing clinical issue, DRESIS is expected to have great implications for future new drug discovery and clinical treatment optimization. It is now publicly accessible without any login requirement at: https://idrblab.org/dresis/.

Heparin and Heparin-Based Drug Delivery Systems: Pleiotropic Molecular Effects at Multiple Drug Resistance of Osteosarcoma and Immune Cells

One of the main problems of modern health care is the growing number of oncological diseases both in the elderly and young population. Inadequately effective chemotherapy, which remains the main method of cancer control, is largely associated with the emergence of multidrug resistance in tumor cells. The search for new solutions to overcome the resistance of malignant cells to pharmacological agents is being actively pursued. Another serious problem is immunosuppression caused both by the tumor cells themselves and by antitumor drugs. Of great interest in this context is heparin, a biomolecule belonging to the class of glycosaminoglycans and possessing a broad spectrum of biological activity, including immunomodulatory and antitumor properties. In the context of the rapid development of the new field of “osteoimmunology,” which focuses on the collaboration of bone and immune cells, heparin and delivery systems based on it may be of intriguing importance for the oncotherapy of malignant bone tumors. Osteosarcoma is a rare but highly aggressive, chemoresistant malignant tumor that affects young adults and is characterized by constant recurrence and metastasis. This review describes the direct and immune-mediated regulatory effects of heparin and drug delivery systems based on it on the molecular mechanisms of (multiple) drug resistance in (onco) pathological conditions of bone tissue, especially osteosarcoma.

The application of cancer stem cell model in malignant mesothelioma

The high mortality rate of malignant pleural mesothelioma led to study the mechanisms for chemoresistance. The cancer stem cell (CSC) model has been proposed to explain chemoresistance. CSCs are characterized by self-renewal capacity, that is detected through tumor-initiating cell assays. As in other malignancies, many studies sought to identify surface markers to isolate CSCs from malignant mesothelioma. Other studies characterized malignant mesothelioma CSCs for the expression of specific genes involved in stemness and the expression of proteins involved in chemoresistance. However, the main methods to characterize isolated CSCs include sphere formation, invasiveness, tumor-initiating capacity and expression of specific surface markers. The better knowledge of malignant mesothelioma CSCs allowed exploring new potential targets to develop specific treatments.

Extracellular Vesicles and the Inflammasome: An Intricate Network Sustaining Chemoresistance

Extracellular vesicles (EVs) are membrane enclosed spherical particles devoted to intercellular communication. Cancer-derived EVs (Ca-EVs) are deeply involved in tumor microenvironment remodeling, modifying the inflammatory phenotype of cancerous and non-cancerous residing cells. Inflammation plays a pivotal role in initiation, development, and progression of many types of malignancies. The key feature of cancer-related inflammation is the production of cytokines that incessantly modify of the surrounding environment. Interleukin-1β (IL-1β) is one of the most powerful cytokines, influencing all the initiation-to-progression stages of many types of cancers and represents an emerging critical contributor to chemoresistance. IL-1β production strictly depends on the activation of inflammasome, a cytoplasmic molecular platform sensing exogenous and endogenous danger signals. It has been recently shown that Ca-EVs can activate the inflammasome cascade and IL-1β production in tumor microenvironment-residing cells. Since inflammasome dysregulation has been established as crucial regulator in inflammation-associated tumorigenesis and chemoresistance, it is conceivable that the use of inflammasome-inhibiting drugs may be employed as adjuvant chemotherapy to counteract chemoresistance. This review focuses on the role of cancer-derived EVs in tuning tumor microenvironment unveiling the intricate network between inflammasome and chemoresistance.

Mechanisms of cancer stem cells drug resistance and the pivotal role of HMGA2

Nowadays, the focus of researchers is on perceiving the heterogeneity observed in a tumor. The researchers studied the role of a specific subset of cancer cells with high resistance to traditional treatments, recurrence, and unregulated metastasis. This small population of tumor cells that have stem-cell-like specifications was named Cancer Stem Cells (CSCs). The unique features that distinguish this type of cancer cell are self-renewing, generating clones of the tumor, plasticity, recurrence, and resistance to therapies. There are various mechanisms that contribute to the drug resistance of CSCs, such as CSCs markers, Epithelial mesenchymal transition, hypoxia, other cells, inflammation, and signaling pathways. Recent investigations have revealed the primary role of HMGA2 in the development and invasion of cancer cells. Importantly, HMGA2 also plays a key role in resistance to treatment through their function in the drug resistance mechanisms of CSCs and challenge it. Therefore, a deep understanding of this issue can provide a clearer perspective for researchers in the face of this problem.

Forchlorfenuron and Novel Analogs Cause Cytotoxic Effects in Untreated and Cisplatin-Resistant Malignant Mesothelioma-Derived Cells

Malignant mesothelioma (MM) is a currently incurable, aggressive cancer derived from mesothelial cells, most often resulting from asbestos exposure. The current first-line treatment in unresectable MM is cisplatin/pemetrexed, which shows very little long-term effectiveness, necessitating research for novel therapeutic interventions. The existing chemotherapies often act on the cytoskeleton, including actin filaments and microtubules, but recent advances indicate the ‘fourth’ form consisting of the family of septins, representing a novel target. The septin inhibitor forchlorfenuron (FCF) and FCF analogs inhibit MM cell growth in vitro, but at concentrations which are too high for clinical applications. Based on the reported requirement of the chloride group in the 2-position of the pyridine ring of FCF for MM cell growth inhibition and cytotoxicity, we systematically investigated the importance (cell growth-inhibiting capacity) of the halogen atoms fluorine, chlorine, bromine and iodine in the 2- or 3-position of the pyridine ring. The MM cell lines ZL55, MSTO-211H, and SPC212, and—as a control—immortalized Met-5A mesothelial cells were used. The potency of the various halogen substitutions in FCF was mostly correlated with the atom size (covalent radius); the small fluoride analogs showed the least effect, while the largest one (iodide) most strongly decreased the MTT signals, in particular in MM cells derived from epithelioid MM. In the latter, the strongest effects in vitro were exerted by the 2-iodo and, unexpectedly, the 2-trifluoromethyl (2-CF3) FCF analogs, which were further tested in vivo in mice. However, FCF-2-I and, more strongly, FCF-2-CF3 caused rapidly occurring strong symptoms of systemic toxicity at doses lower than those previously obtained with FCF. Thus, we investigated the effectiveness of FCF (and selected analogs) in vitro in MM cells which were first exposed to cisplatin. The slowly appearing population of cisplatin-resistant cells was still susceptible to the growth-inhibiting/cytotoxic effect of FCF and its analogs, indicating that cisplatin and FCF target non-converging pathways in MM cells. Thus, a combination therapy of cisplatin and FCF (analogs) might represent a new avenue for the treatment of repopulating chemo-resistant MM cells in this currently untreatable cancer.

Cancer-associated fibroblast-induced lncRNA UPK1A-AS1 confers platinum resistance in pancreatic cancer via efficient double-strand break repair

The tumor stroma of pancreatic ductal adenocarcinoma (PDAC) is characterized by an abundant and heterogeneous population of cancer-associated fibroblasts (CAFs), which are critically involved in chemoresistance. However, the underlying mechanism of CAFs in chemoresistance is unclear. Here, we show that CAFR, a CAF subset derived from platinum-resistant PDAC patients, assumes an iCAF phenotype and produces more IL8 than CAFS isolated from platinum-sensitive PDAC patients. CAFR-derived IL8 promotes oxaliplatin chemoresistance in PDAC. Based on long noncoding RNA (lncRNA) profiling in tumor cells incubated with CAF-CM, we found that UPK1A-AS1, whose expression is directly induced by IL8/NF-kappa B signaling, functions as a chemoresistance-promoting lncRNA and is critical for active IL8-induced oxaliplatin resistance. Impressively, blocking the activation of UPK1A-AS1 expression increases the oxaliplatin sensitivity of tumor cells in vivo. Mechanistically, UPK1A-AS1 strengthens the interaction between Ku70 and Ku80 to facilitate nonhomologous end joining (NHEJ), thereby enhancing DNA double-strand break (DSB) repair. Clinically, UPK1A-AS1 expression is positively correlated with IL8 expression, a poor chemotherapeutic response and a shorter progression-free survival (PFS) time in advanced PDAC patients. Collectively, our study reveals a lncRNA-mediated mechanism of CAF-derived paracrine IL8-dependent oxaliplatin resistance and highlights UPK1A-AS1 as a potential therapeutic target.

Transient Receptor Potential Cation Channel Subfamily V Member 1 Expression Promotes Chemoresistance in Non-Small-Cell Lung Cancer

Approximately 85% of lung cancer cases are non-small-cell lung cancer (NSCLC). Chemoresistance is a leading cause of chemotherapy failure in NSCLC treatment. Transient receptor potential cation channel subfamily V, member 1 (TRPV1), a non-selective cation channel, plays multiple roles in tumorigenesis and tumor development, including tumor cell proliferation, death, and metastasis as well as the response to therapy. In this study, we found TRPV1 expression was increased in NSCLC. TRPV1 overexpression induced cisplatin (DDP) and fluorouracil (5-FU) resistance in A549 cells independent of its channel function. TRPV1 expression was upregulated in A549-DDP/5-FU resistant cells, and DDP/5-FU sensitivity was restored by TRPV1 knockdown. TRPV1 overexpression mediated DDP and 5-FU resistance by upregulation of ABCA5 drug transporter gene expression, thereby increasing drug efflux, enhancing homologous recombination (HR) DNA repair pathway to alleviate apoptosis and activating IL-8 signaling to promote cell survival. These findings demonstrate an essential role of TRPV1 in chemoresistance in NSCLC and implicate TRPV1 as a potential chemotherapeutic target.

SKP2 drives the sensitivity to neddylation inhibitors and cisplatin in malignant pleural mesothelioma

Background

The combination of pemetrexed and cisplatin remains the reference first-line systemic therapy for malignant pleural mesothelioma (MPM). Its activity is moderate because of tumor aggressiveness, immune-suppressive environment and resistance to chemotherapy-induced immunogenic cell death (ICD). Preliminary and limited findings suggest that MPM cells have deregulated ubiquitination and proteasome activities, although proteasome inhibitors achieved disappointing clinical results.

Methods

Here, we investigated the role of the E3-ubiquitin ligase SKP/Cullin/F-box (SCF) complex in cell cycle progression, endoplasmic reticulum (ER)/proteostatic stress and ICD in MPM, and the therapeutic potential of the neddylation/SCF complex inhibitor MLN4924/Pevonedistat.

Results

In patient-derived MPM cultures and syngenic murine models, MLN4924 and cisplatin showed anti-tumor effects, regardless of MPM histotype and BAP1 mutational status, increasing DNA damage, inducing S- and G2/M-cell cycle arrest, and apoptosis. Mechanistically, by interfering with the neddylation of cullin-1 and ubiquitin-conjugating enzyme UBE2M, MLN4924 blocks the SCF complex activity and triggers an ER stress-dependent ICD, which activated anti-MPM CD8⁺T-lymphocytes. The SKP2 component of SCF complex was identified as the main driver of sensitivity to MLN4924 and resistance to cisplatin. These findings were confirmed in a retrospective MPM patient series, where SKP2 high levels were associated with a worse response to platinum-based therapy and inferior survival.

Conclusions

We suggest that the combination of neddylation inhibitors and cisplatin could be worth of further investigation in the clinical setting for MPM unresponsive to cisplatin. We also propose SKP2 as a new stratification marker to determine the sensitivity to cisplatin and drugs interfering with ubiquitination/proteasome systems in MPM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02284-7.

Cancer Stem Cells Contribute to Drug Resistance in Multiple Different Ways

Many tumors are resistant to conventional cancer therapies because a tumor is composed of heterogeneous cell population. Especially, subpopulation of cancer stem cells, which have self-renewal and differentiation properties and responsible for the tumor initiation, is generally considered resistant to chemo-, radio-, and immune therapy. Understanding the mechanism of drug resistance in cancer stem cells should lead to establish more effective therapeutic strategies. Actually, different molecular mechanisms are conceivable for cancer stem cells acquiring drug resistance. These mechanisms include not only cytoplasmic signaling pathways but also the intercellular communications in the tumor microenvironment. Recently, a great deal of successful reports challenged to elucidate the mechanisms of drug resistance and to develop novel treatments targeting cancer stem cells.

Mesothelioma Malignancy and the Microenvironment: Molecular Mechanisms

Several studies have reported that cellular and soluble components of the tumor microenvironment (TME) play a key role in cancer-initiation and progression. Considering the relevance and the complexity of TME in cancer biology, recent research has focused on the investigation of the TME content, in terms of players and informational exchange. Understanding the crosstalk between tumor and non-tumor cells is crucial to design more beneficial anti-cancer therapeutic strategies. Malignant pleural mesothelioma (MPM) is a complex and heterogenous tumor mainly caused by asbestos exposure with few treatment options and low life expectancy after standard therapy. MPM leukocyte infiltration is rich in macrophages. Given the failure of macrophages to eliminate asbestos fibers, these immune cells accumulate in pleural cavity leading to the establishment of a unique inflammatory environment and to the malignant transformation of mesothelial cells. In this inflammatory landscape, stromal and immune cells play a driven role to support tumor development and progression via a bidirectional communication with tumor cells. Characterization of the MPM microenvironment (MPM-ME) may be useful to understand the complexity of mesothelioma biology, such as to identify new molecular druggable targets, with the aim to improve the outcome of the disease. In this review, we summarize the known evidence about the MPM-ME network, including its prognostic and therapeutic relevance.

Impact of ABC Transporters in Osteosarcoma and Ewing's Sarcoma: Which Are Involved in Chemoresistance and Which Are Not?

The ATP-binding cassette (ABC) transporter superfamily consists of several proteins with a wide repertoire of functions. Under physiological conditions, ABC transporters are involved in cellular trafficking of hormones, lipids, ions, xenobiotics, and several other molecules, including a broad spectrum of chemical substrates and chemotherapeutic drugs. In cancers, ABC transporters have been intensely studied over the past decades, mostly for their involvement in the multidrug resistance (MDR) phenotype. This review provides an overview of ABC transporters, both related and unrelated to MDR, which have been studied in osteosarcoma and Ewing's sarcoma. Since different backbone drugs used in first-line or rescue chemotherapy for these two rare bone sarcomas are substrates of ABC transporters, this review particularly focused on studies that have provided findings that have been either translated to clinical practice or have indicated new candidate therapeutic targets; however, findings obtained from ABC transporters that were not directly involved in drug resistance were also discussed, in order to provide a more complete overview of the biological impacts of these molecules in osteosarcoma and Ewing's sarcoma. Finally, therapeutic strategies and agents aimed to circumvent ABC-mediated chemoresistance were discussed to provide future perspectives about possible treatment improvements of these neoplasms.

Drug Resistance in Osteosarcoma: Emerging Biomarkers, Therapeutic Targets and Treatment Strategies

Simple Summary

Despite the adoption of aggressive, multimodal treatment schedules, the cure rate of high-grade osteosarcoma (HGOS) has not significantly improved in the last 30 years. The most relevant problem preventing improvement in HGOS prognosis is drug resistance. Therefore, validated novel biomarkers that help to identify those patients who could benefit from innovative treatment options and the development of drugs enabling personalized therapeutic protocols are necessary. The aim of this review was to give an overview on the most relevant emerging drug resistance-related biomarkers, therapeutic targets and new agents or novel candidate treatment strategies, which have been highlighted and suggested for HGOS to improve the success rate of clinical trials.

Abstract

High-grade osteosarcoma (HGOS), the most common primary malignant tumor of bone, is a highly aggressive neoplasm with a cure rate of approximately 40–50% in unselected patient populations. The major clinical problems opposing the cure of HGOS are the presence of inherent or acquired drug resistance and the development of metastasis. Since the drugs used in first-line chemotherapy protocols for HGOS and clinical outcome have not significantly evolved in the past three decades, there is an urgent need for new therapeutic biomarkers and targeted treatment strategies, which may increase the currently available spectrum of cure modalities. Unresponsive or chemoresistant (refractory) HGOS patients usually encounter a dismal prognosis, mostly because therapeutic options and drugs effective for rescue treatments are scarce. Tailored treatments for different subgroups of HGOS patients stratified according to drug resistance-related biomarkers thus appear as an option that may improve this situation. This review explores drug resistance-related biomarkers, therapeutic targets and new candidate treatment strategies, which have emerged in HGOS. In addition to consolidated biomarkers, specific attention has been paid to the role of non-coding RNAs, tumor-derived extracellular vesicles, and cancer stem cells as contributors to drug resistance in HGOS, in order to highlight new candidate markers and therapeutic targets. The possible use of new non-conventional drugs to overcome the main mechanisms of drug resistance in HGOS are finally discussed.

Histopathological typing in diffuse malignant epithelioid mesothelioma: implication for prognosis and molecular basis

The prognostic impact of tumour grading, cytological and architectural patterns and stromal features in diffuse pleural malignant epithelioid mesothelioma (MEM) has been partly studied but not correlated to molecular features. We performed a retrospective study on 92 MEM in our department in order to assess the prognostic role of architectural and stromal patterns, especially tumour to stroma ratio. Secondly, based on The Cancer Genome Atlas (TCGA) database, we analysed the differentially expressed genes in prognostic groups of interest. Our results showed that tumour grading, tumour to stroma ratio and predominant pattern were related to overall survival, p≤0.001, p=0.01 and p=0.001, respectively. In univariate analysis, for high grade tumours hazard ratio (HR) was 4.75 (2.47-9.16), for stroma poor tumours HR=0.016, for predominant tubular or tubulopapillary pattern HR=0.044. In multivariate analysis, high grade tumours were related to overall survival [HR=3.09 (1.50-6.35), p=0.002] and predominant tubular or tubulopapillary pattern [HR=0.56 (0.32-0.99), p=0.045]. In TCGA analysis, after grading of diagnostic slides, we showed that KRTDAP and CXRCR1 expression was higher in low grade tumours, unlike PDZD7 and GPR176 expression which was higher in high grade tumours. FAM81B had a higher expression in stroma poor tumours. We did not find any differentially expressed genes in the architectural patterns group. Our work suggests that tumour grading is an important parameter in MEM with an underlying genomic basis. The role of tumour to stroma ratio needs to be investigated and might also have a genomic basis.

Transcriptomic alterations in malignant pleural mesothelioma cells in response to long‑term treatment with bullfrog sialic acid‑binding lectin

Malignant pleural mesothelioma (MPM) is a universally lethal type of cancer that is increasing in incidence worldwide; therefore, the development of new drugs for MPM is an urgent task. Bullfrog sialic acid-binding lectin (cSBL) is a multifunctional protein that has carbohydrate-binding and ribonuclease activities. cSBL exerts marked antitumor activity against numerous types of cancer cells, with low toxicity to normal cells. Although in vitro and in vivo studies revealed that cSBL was effective against MPM, the mechanism by which cSBL exerts antitumor effects is not fully understood. To further understand the mechanism of action of cSBL, the present study aimed to identify the key molecules whose expression was affected by cSBL. The present study established cSBL-resistant MPM cells. Microarray analyses revealed that there were significant pleiotropic changes in the expression profiles of several genes, including multiple genes involved in metabolic pathways in cSBL-resistant cells. Furthermore, the expression of some members of the aldo-keto reductase family was revealed to be markedly downregulated in these cells. Among these, it was particularly interesting that cSBL action reduced the level of AKR1B10, which has been reported as a biomarker candidate for MPM prognosis. These findings revealed novel aspects of the effect of cSBL, which may contribute to the development of new therapeutic strategies for MPM.

Human drug efflux transporter ABCC5 confers acquired resistance to pemetrexed in breast cancer

Aim

Pemetrexed, a new generation antifolate drug, has been approved for the treatment of locally advanced or metastatic breast cancer. However, factors affecting its efficacy and resistance have not been fully elucidated yet. ATP-binding cassette (ABC) transporters are predictors of prognosis as well as of adverse effects of several xenobiotics. This study was designed to explore whether ABC transporters affect pemetrexed resistance and can contribute to the optimization of breast cancer treatment regimen.

Methods

First, we measured the expression levels of ABC transporter family members in cell lines. Subsequently, we assessed the potential role of ABC transporters in conferring resistance to pemetrexed in primary breast cancer cells isolated from 34 breast cancer patients and the role of ABCC5 in mediating pemetrexed transport and apoptotic pathways in MCF-7 cells. Finally, the influence of ABCC5 expression on the therapeutic effect of pemetrexed was evaluated in an in vivo xenograft mouse model of breast cancer.

Results

The expression levels of ABCC2, ABCC4, ABCC5, and ABCG2 significantly increased in the pan-resistant cell line, and the ABCC5 level in the MCF-7-ADR cell line was 5.21 times higher than that in the control group. ABCC5 expression was inversely correlated with pemetrexed sensitivity (IC₅₀, r = 0.741; p < 0.001) in breast cancer cells derived from 34 patients. Furthermore, we found that the expression level of ABCC5 influenced the efflux and cytotoxicity of pemetrexed in MCF-7 cells, with IC₅₀ values of 0.06 and 0.20 μg/mL in ABCC5 knockout and over-expression cells, respectively. In the in vivo study, we observed that ABCC5 affected the sensitivity of pemetrexed in breast tumor-bearing mice, and the tumor volume was much larger in the ABCC5-overexpressing group than in the control group when compared with their own initial volumes (2.7-fold vs. 1.3-fold).

Conclusions

Our results indicated that ABCC5 expression was associated with pemetrexed resistance in vitro and in vivo, and it may serve as a target or biomarker for the optimization of pemetrexed regimen in breast cancer treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01842-x.

Drug resistance and Cancer stem cells

Therapy resistance is a major problem when treating cancer patients as cancer cells develop mechanisms that counteract the effect of therapeutic compounds, leading to fit and more aggressive clones that contribute to poor prognosis. Therapy resistance can be both intrinsic and/or acquired. These are multifactorial events, and some are related to factors including adaptations in cancer stem cells (CSCs), epithelial-mesenchymal transition (EMT), deregulation of key signaling pathways, drug efflux through ABC transporters, acquired mutations, evading apoptosis, and activation of DNA damage response among others. Among these factors, CSCs represent the major source of therapy resistance. CSCs are a subset of tumor cells that are capable of self-renewal and multilineage progenitor expansion that are known to be intrinsically resistant to anticancer treatments. Multiple clones of CSCs pre-exist, and some can adopt and expand easily to changes in the tumor microenvironment (TME) and/or in response to radio- and chemotherapy. A combination of both intrinsic and extrinsic factors contributes to CSC-mediated therapy resistance. In this review, we will focus on CSCs and therapy resistance as well as suggest strategies to eliminate CSCs and, therefore, overcome resistance. Video abstract.

HDAC1 regulates the chemosensitivity of laryngeal carcinoma cells via modulation of interleukin-8 expression

Chemotherapies such as 5-fluorouracil (5-FU) and cisplatin (CDDP) have been widely used to treat laryngeal squamous cell carcinoma (LSCC), the second most common head and neck squamous cell carcinoma. However, chemoresistance seriously impairs chemotherapeutic efficacy. Our present study reveals that 5-FU and CDDP treatment increase the expression of histone deacetylase 1 (HDAC1) in LSCC cells. Consistently, increased levels of HDAC1 are observed in chemoresistant cells. Knockdown of HDAC1 significantly restores the sensitivity of LSCC cells, as HDAC1 increases the expression of interleukin-8 (IL-8), which is essential for LSCC chemoresistance. Mechanistically, HDAC1 directly initiates the transcription of IL-8 though binding to its promoter. Simultaneously, si-HDAC1 increases the levels of miR-93, which binds to the 3'UTR of IL-8 mRNA to trigger its degradation. In summary, the HDAC1/IL-8 axis can confer chemotherapeutic resistance to LSCC cells.

Hypoxia, endoplasmic reticulum stress and chemoresistance: dangerous liaisons

Solid tumors often grow in a micro-environment characterized by < 2% O₂ tension. This condition, together with the aberrant activation of specific oncogenic patwhays, increases the amount and activity of the hypoxia-inducible factor-1α (HIF-1α), a transcription factor that controls up to 200 genes involved in neoangiogenesis, metabolic rewiring, invasion and drug resistance. Hypoxia also induces endoplasmic reticulum (ER) stress, a condition that triggers cell death, if cells are irreversibly damaged, or cell survival, if the stress is mild.Hypoxia and chronic ER stress both induce chemoresistance. In this review we discuss the multiple and interconnected circuitries that link hypoxic environment, chronic ER stress and chemoresistance. We suggest that hypoxia and ER stress train and select the cells more adapted to survive in unfavorable conditions, by activating pleiotropic mechanisms including apoptosis inhibition, metabolic rewiring, anti-oxidant defences, drugs efflux. This adaptative process unequivocally expands clones that acquire resistance to chemotherapy.We believe that pharmacological inhibitors of HIF-1α and modulators of ER stress, although characterized by low specificty and anti-cancer efficacy when used as single agents, may be repurposed as chemosensitizers against hypoxic and chemorefractory tumors in the next future.

Hypoxia Dictates Metabolic Rewiring of Tumors: Implications for Chemoresistance

Hypoxia is a condition commonly observed in the core of solid tumors. The hypoxia-inducible factors (HIF) act as hypoxia sensors that orchestrate a coordinated response increasing the pro-survival and pro-invasive phenotype of cancer cells, and determine a broad metabolic rewiring. These events favor tumor progression and chemoresistance. The increase in glucose and amino acid uptake, glycolytic flux, and lactate production; the alterations in glutamine metabolism, tricarboxylic acid cycle, and oxidative phosphorylation; the high levels of mitochondrial reactive oxygen species; the modulation of both fatty acid synthesis and oxidation are hallmarks of the metabolic rewiring induced by hypoxia. This review discusses how metabolic-dependent factors (e.g., increased acidification of tumor microenvironment coupled with intracellular alkalinization, and reduced mitochondrial metabolism), and metabolic-independent factors (e.g., increased expression of drug efflux transporters, stemness maintenance, and epithelial-mesenchymal transition) cooperate in determining chemoresistance in hypoxia. Specific metabolic modifiers, however, can reverse the metabolic phenotype of hypoxic tumor areas that are more chemoresistant into the phenotype typical of chemosensitive cells. We propose these metabolic modifiers, able to reverse the hypoxia-induced metabolic rewiring, as potential chemosensitizer agents against hypoxic and refractory tumor cells.

Interleukin-8: A chemokine at the intersection of cancer plasticity, angiogenesis, and immune suppression

Tumor progression relies on the ability of cancer cells to effectively invade surrounding tissues and propagate. Among the many mechanisms that contribute to tumor progression is the epithelial-to-mesenchymal transition (EMT), a phenotypic plasticity phenomenon that increases the cancer cells' motility and invasiveness and influences their surrounding microenvironment by promoting the secretion of a variety of soluble factors. One such factor is IL-8, a chemokine with multiple pro-tumorigenic roles within the tumor microenvironment (TME), including stimulating proliferation or transformation of tumor cells into a migratory or mesenchymal phenotype. Further, IL-8 can increase tumor angiogenesis or recruit larger numbers of immunosuppressive cells to the tumor. Prognostically, observations in many tumor types show that patients with higher levels of IL-8 at baseline experience worse clinical outcomes. Additionally, studies have shown that the chemokine directly contributes to the development of resistance to both chemotherapy and molecularly targeted agents. More recently, clinical studies evaluating levels of IL-8 in patients receiving immune checkpoint inhibition (ICI) therapy deduced that myeloid tumor infiltration driven by IL-8 contributes to resistance to ICI agents and that peripheral IL-8 can predict outcomes to ICI therapy. Further, pre-clinical data demonstrate that targeting IL-8 or its receptors enables improved tumor killing by immune cells, and treatment strategies combining blockade of the IL-8/IL-8R axis with ICI ultimately improve anti-tumor efficacy. Based on these results and the prognostic capacity of IL-8, there are a number of ongoing clinical trials evaluating the addition of IL-8 targeting strategies to immune-based therapies.

Blocking the autocrine regulatory loop of Gankyrin/STAT3/CCL24/CCR3 impairs the progression and pazopanib resistance of clear cell renal cell carcinoma

The poor prognosis of clear-cell renal cell carcinoma (ccRCC) patients is due to progression and targeted drug resistance, but the underlying molecular mechanisms need further elucidation. This study examined the biological function and related mechanisms of gankyrin in ccRCC based on the results of our previous study. To this end, in vitro functional experiments; in vivo models of subcutaneous tumor formation, lung metastasis, and orthotopic ccRCC; and antibody chip detection, co-IP, ChIP assays were performed to examine the biological role and molecular mechanisms of gankyrin in ccRCC. Two hundred fifty-six ccRCC patients were randomly divided into training and validation cohorts to examine the prognostic value of gankyrin and other markers through IHC and statistical analyses. We observed that the gankyrin-overexpressing ccRCC cell lines 786-O and 769-P exhibited increased proliferation, invasion, migration, tumorigenicity, and pazopanib resistance and decreased apoptosis, while gankyrin knockdown achieved the opposite results. Mechanistically, gankyrin recruited STAT3 via direct binding, and STAT3 binding to the CCL24 promoter promoted its expression. Reciprocally, an increase in autocrine CCL24 enhanced the expression of gankyrin and STAT3 activation via CCR3 in ccRCC, forming a positive autocrine-regulatory loop. Furthermore, in vivo experimental results revealed that blocking the positive loop through gankyrin knockdown or treatment with the CCR3 inhibitor SB328437 reversed the resistance to pazopanib and inhibited lung metastasis in ccRCC. Moreover, a positive correlation between gankyrin and STAT3 or CCL24 expression in ccRCC specimens was observed, and improved accuracy for ccRCC patient prognosis was achieved by combining gankyrin and STAT3 or CCL24 expression with existing clinical prognostic indicators, including the TNM stage and SSIGN score. In summary, targeting the gankyrin/STAT3/CCL24/CCR3 autocrine-regulatory loop may serve as a remedy for patients with advanced ccRCC, and combining gankyrin and STAT3 or CCL24 expression with the current clinical indicators better predicts ccRCC patient prognosis.

Emetine Synergizes with Cisplatin to Enhance Anti-Cancer Efficacy against Lung Cancer Cells

Cisplatin is still the primary therapeutic choice for advanced lung cancers without driver mutations. The occurrence of cisplatin resistance is a major clinical problem in lung cancer treatment. The natural extracted agent emetine reportedly has anticancer effects. This study aimed to explore the possible role of emetine in cisplatin resistance. We used cell viability, Western blot, and Wnt reporter assays to show that emetine suppresses proliferation, β-catenin expression, and Wnt/β-catenin signaling in non-small cell lung cancer (NSCLC). The synergism of emetine and cisplatin was assessed by constructing isobolograms and calculating combination index (CI) values using the Chou-Talalay method. Emetine effectively synergized with cisplatin to suppress the proliferation of cancer cells. Furthermore, nuclear β-catenin and cancer stem cell-related markers were upregulated in the cisplatin-resistant subpopulation of CL1-0 cells. Emetine enhanced the anticancer efficacy of cisplatin and synergized with cisplatin in the cisplatin-resistant subpopulation of CL1-0 cells. Taken together, these data suggest that emetine could suppress the growth of NSCLC cells through the Wnt/β-catenin pathway and contribute to a synergistic effect in combination with cisplatin.