Bulk Cancer Cells Research Articles

Suppression of ovarian cancer by low-intensity ultrasound through depletion of IL-6/STAT3 inflammatory pathway-maintained cancer stemness

Ovarian carcinoma is the key cause of cancer death from gynecological malignancy of women. Chemotherapy-resistance, metastasis and relapse contribute to the high mortality in ovarian cancer patients. Cancer stem cells (CSCs) stand for the root of kinds of cancer types such as ovarian cancer, are the key driver of tumor initiation, cancer metastasis, and resistance to conventional chemotherapy as well as genomic targeted therapy. Thus, the approach to eliminate CSCs and uncovering the mechanism will have substantial impact on cancer therapy. However, targeting CSC remains unfeasible in clinical practice in ovarian cancer therapy. In this study, we first found that Low-intensity ultrasound (LIUS) was capable of reducing the CSC populations in the xenograft model with ovarian cancer, with blocking survival, anti-apoptosis, self-renewal, and downregulating the cancer stemness genes in ovarian CSCs. Moreover, LIUS ameliorated IL-6/STAT3 inflammatory pathway via inhibiting IL-6-induced STAT3 phosphorylation, DNA binding activity and, the expressions of its downstream effectors in ovarian CSCs while no explicit effect was found in the corresponding bulk cancer cells. Additional approaches in molecular studies showed that LIUS disrupts CSC features via inhibiting IL-6/STAT3 inflammatory pathway. Collectively, our data for the first time elucidate IL-6/STAT3 inflammatory loop as the key CSC or cancer stemness pathway in ovarian cancer by LIUS treatment, providing a novel and potential therapy and a promising target in ovarian cancer.

Poly-aneuploid cancer cells promote evolvability, generating lethal cancer.

Cancer cells utilize the forces of natural selection to evolve evolvability allowing a constant supply of heritable variation that permits a cancer species to evolutionary track changing hazards and opportunities. Over time, the dynamic tumor ecosystem is exposed to extreme, catastrophic changes in the conditions of the tumor—natural (e.g., loss of blood supply) or imposed (therapeutic). While the nature of these catastrophes may be varied or unique, their common property may be to doom the current cancer phenotype unless it evolves rapidly. Poly‐aneuploid cancer cells (PACCs) may serve as efficient sources of heritable variation that allows cancer cells to evolve rapidly, speciate, evolutionarily track their environment, and most critically for patient outcome and survival, permit evolutionary rescue, therapy resistance, and metastasis. As a conditional evolutionary strategy, they permit the cancer cells to accelerate evolution under stress and slow down the generation of heritable variation when conditions are more favorable or when the cancer cells are closer to an evolutionary optimum. We hypothesize that they play a critical and outsized role in lethality by their increased capacity for invasion and motility, for enduring novel and stressful environments, and for generating heritable variation that can be dispensed to their 2N+ aneuploid progeny that make up the bulk of cancer cells within a tumor, providing population rescue in response to therapeutic stress. Targeting PACCs is essential to cancer therapy and patient cure—without the eradication of the resilient PACCs, cancer will recur in treated patients.

Voltage Dependent Anion Channels Regulate Proliferation of Cancer Stem Cells

Cancer stem cells (CSCs) are associated with tumor progression and resistance to chemotherapy. Oxidative phosphorylation and aerobic glycolysis in CSCs are dynamically regulated. Mitochondrial metabolism and membrane potential (ΔΨ) are contributed by the ingress of respiratory substrates, ADP and Pi into mitochondria through voltage-dependent anion channels 1/2/3 (VDAC). We previously demonstrated that free tubulin closes VDAC and erastin antagonizes the tubulin inhibition of VDAC1/2 but not VDAC3. VDAC opening increases mitochondrial metabolism decreasing glycolysis and proliferation. Here, we hypothesized that different VDAC isoforms, by controlling oxidative metabolism, regulate proliferation of CSCs. CSCs from HepG2 and Huh7 human hepatocarcinoma and HCC4006 lung adenocarcinoma cells (spheres >50 µm diameter) were generated using ultra-low attachment plates (DMEM-F12 medium supplemented with B-27, EGF and bFGF). Markers of pluripotency were assessed by qPCR, western blotting and immunostaining. Spheres were counted using 50 µm side grid units. Tetramethylrhodamine methyl ester fluorescence to assess ΔΨ was determined both using a microplate reader and confocal fluorescence microscopy. The relative contribution of each VDAC isoform was similar in all CSCs and bulk cancer cells (CCs). By contrast, VDAC 2/3 mRNA levels were higher in CSCs compared to bulk HepG2, Huh7 and HCC4006 whereas VDAC1 was higher only in HepG2 and Huh7 CSCs. VDAC1 single knockdown in HepG2 and Huh7 CSCs decreased sphere formation by ∼30%. VDAC2 and VDAC3 single knockdown increased both the amount (∼18% and 102%, respectively) and the size of spheroids. VDAC1/2/3 single knockdown decreased ΔΨ. Erastin decreased sphere formation and promoted intra-sphere cell death in HepG2 and Huh7 CSCs. VDAC1/2 but not VDAC3 contribute to the maintenance and proliferation of CSCs. VDAC1/2 opening by erastin may decrease sphere formation and promote cell death by enhancing oxidative metabolism and decreasing glycolysis.

High aldehyde dehydrogenase activity does not protect colon cancer cells against TPCS2a-sensi-tized photokilling

Aldehyde dehydrogenases (ALDH) are detoxifying enzymes that are upregulated in cancer stem cells (CSCs) and may cause chemo-and ionizing radiation (IR) therapy resistance. By using the ALDEFLUOR assay, CD133 + human colon cancer cells HT-29, were FACSorted into three populations: ALDHbright, ALDHdim and unsorted (bulk) and treated with chemo-, radio- or photodynamic therapy (PDT) using the clinical relevant photosensitizer disulfo-nated tetraphenyl chlorin (TPCS2a/fimaporfin). Here we show that there is no difference in cytotoxic responses to TPCS2a-PDT in ALHDbright, ALDHdim or bulk cancer cells. Likewise, both 5-FU and oxaliplatin chemotherapy efficacy was not reduced in ALDHbright as compared to ALDHdim cancer cells. However, we found that ALHDbright HT-29 cells are significantly less sensitive to ionizing radiation compared to ALDHdim cells. This study demonstrates that the cytotoxic response to PDT (using TPCS2a as photosensitizer) is independent of ALDH activity in HT-29 cancer cells. Our results further strengthen the use of TPCS2a to target CSCs.

Inhibition of 3D colon cancer stem cell spheroids by cytotoxic RuII-p-cymene complexes of mesalazine derivatives.

The Ru(ii) complex of an imidazole-mesalazine Schiff base is a unique example showing growth inhibition of 3D-colon cancer stem cell spheroids and bulk colon cancer cells at lower dosage than salinomycin or oxaliplatin. Unlike oxaliplatin which increases the expression of stemness genes (SOX2, KLF4, HES1 and Oct4), these complexes maintain a tight regulation.

A tri-metallic palladium complex with breast cancer stem cell potency.

A multi-nuclear, triangular-shaped palladium(ii) complex is shown to equipotently kill bulk cancer cells and cancer stem cells (CSCs) in the micromolar range. The palladium(ii) complex evokes CSC apoptosis by entering CSC nuclei and damaging genomic DNA.

Actinomycin D and Telmisartan Combination Targets Lung Cancer Stem Cells Through the Wnt/Beta Catenin Pathway

The failure of lung cancer treatments has been attributed mostly to the development of drug resistance, however the underlying cellular and molecular mechanisms are poorly understood. Cancer initiating stem cells (CSCs), present in tumors in a small percentage, play critical roles in the development of drug resistance, metastasis, and cancer relapse. Hence, novel treatments targeting both bulk cancer cells and CSCs are under intense investigation. Herein, we report that lung cancer cells grown on a 3D fibrous scaffold form tumoroids that resemble in vivo tumors, expand CSCs, and provide a platform to identify anti-CSC drugs. The screening of an NCI library of FDA-approved drugs using tumoroid cultures led to identification of Actinomycin D (AD) as a top CSC inhibitor. Since CSCs are mostly resident in the tumor’s inner core, AD was combined with an angiotensin receptor antagonist, Telmisartan (TS), which is known to increase drug permeability in tumors and was shown to have anti-CSC activity. Our results showed that AD + TS administered intra-tumorally was significantly more effective than either drug alone in both syngeneic and xenograft mouse models. The results of mechanistic studies revealed that CSC expansion in tumoroids was associated with activation of β catenin signaling and that AD + TS treatment reduced active β catenin levels in tumors. Together, these results establish the utility of the tumoroid culture system to expand CSCs ex vivo for targeted drug screening, to identify promising novel treatments with both anti-CSC and anti-cancer effects, and to individualize treatments for metastatic drug resistant lung cancer patients.

Abstract AP32: THE ROLE OF NFAT3 IN OVARIAN CANCER QUIESCENCE AND CHEMOTHERAPY RESISTANCE

Abstract Despite the fact that the majority of patients with ovarian cancer will have a complete clinical remission with combined surgical/chemotherapeutic approaches, Epithelial Ovarian Cancer (EOC) is the fifth most common cause of cancer-related death in American women, with the third highest mortality:incidence ratio. The majority of deaths from ovarian cancer are related to disease recurrence and the subsequent development of ultimately fatal chemotherapy-resistant disease. Elucidating mechanisms of chemoresistance in ovarian cancer cells may identify critical therapeutic targets to prevent or treat relapsed ovarian cancer. One feature that might contribute to the chemotherapy resistance is quiescence. Quiescence describes a reversible non-proliferative cell state. As such, quiescent cells have reduced susceptibility to chemotherapeutics which target rapidly proliferating cells. Indeed, quiescence is a known mechanism of chemotherapy resistance of normal stem cells. In normal stem cells quiescence is mediated by the NFAT family of transcription factors. Unfortunately, very little is known about the factors that mediate ovarian cancer cell quiescence. Using qRT-PCR, we evaluated the expression of NFAT family members in ovarian cancer cells. We found NFAT3 to be enriched in patient ovarian cancer stem-like cells (CSLC) compared to bulk cancer cells. Treatment of EOC cells with cisplatin chemotherapy resulted in a nuclear translocation of NFAT3 and increase in NFAT3 transcriptional activity. To directly investigate the functional role of NFAT3 in ovarian cancer, we created ovarian cancer cell lines expressing constitutively nuclear/active (cNFAT3) or inducible constitutively active (IcNFAT3) NFAT3. We found that while cNFAT3 expression in ovarian cancer cells did not impact cell viability, senescence or apoptosis, cNFAT3 expression profoundly restricted ovarian cancer cell proliferation, with a 3-fold decreased cell division rates, and cellular arrest in the G0 phase of the cell cycle. Consistent with a quiescent cell phenotype, this was associated with a 10% decrease in cell size, and a 25% decrease in total cellular RNA. Induction of cNFAT3 expression in vivo resulted in tumor growth arrest. This growth arrest resulted in chemotherapy resistance such that cNFAT3 tumors treated with high dose of chemotherapy rapidly expanded after cNFAT3 inactivation. Furthermore, NFAT inhibition with the peptide inhibitor VIVIT enhance chemotherapy response in vitro and in vivo. Taken together, our data suggests NFAT3 drives a quiescent state in CSLC and thereby mediates chemoresistance. Thus NFAT3 represents a therapeutic target to both overcome chemotherapy resistance in quiescent cancer cells and to restrict the growth of therapy-resistant disease. Citation Format: Alex J Cole, Mangala Iyengar, Patrick O'Hayer, Kun Yang, Tara Sebastian, Lan Coffman, Ronald J Buckanovich. THE ROLE OF NFAT3 IN OVARIAN CANCER QUIESCENCE AND CHEMOTHERAPY RESISTANCE [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr AP32.

Mithramycin A Inhibits Colorectal Cancer Growth by Targeting Cancer Stem Cells

The pivotal role of cancer initiating stem cells (CSCs) in tumor initiation, growth, metastasis and drug resistance has led to the postulation of a ‘total cancer therapy’ paradigm, which involves targeting both cancer cells and CSCs for effective therapy. However, the progress in identifying drugs for total cancer therapy has been limited. Herein, we show for the first time that mithramycin A (Mit-A) can successfully inhibit CSC proliferation, in addition to inhibiting bulk cancer cells in a model of colorectal cancer (CRC), the second leading cause of death among men and women in the United States. To this end, a polymeric nanofiber scaffold culture system was established to develop 3D tumor organoids (tumoroids) from CRC cell lines such as HT29, HCT116, KM12, CT26 and MC38 as well as ex vivo mouse tumors. These tumoroids possessed increased expression of CSC markers and transcription factors, expanded the number of CSCs in culture and increased CSC functional properties measured by aldehyde dehydrogenase activity. Screening of an NCI library of FDA approved drugs led to the identification of Mit-A as a potential total cancer therapy drug. In both sphere and tumoroid culture, Mit-A inhibits cancer growth by reducing the expression of cancer stemness markers. In addition, Mit-A inhibits the expression of SP1, a previously known target in CRCs. Moreover, Mit-A significantly reduces growth of tumoroids in ex vivo cultures and CRC tumor growth in vivo. Finally, a dose-dependent treatment on CRC cells indicate that Mit-A significantly induces the cell death and PARP-cleavage of both CSC and non-CSC cells. Taken together the results of these in vitro, ex vivo and in vivo studies lead to the inference that Mit-A is a promising drug candidate for total cancer therapy of CRCs.

Clinical and biochemical relevance of monounsaturated fatty acid metabolism targeting strategy for cancer stem cell elimination in colon cancer

Lipid metabolism is associated with colon cancer prognosis and incidence. Stearoyl-CoA desaturase 1 (SCD1), which converts fully saturated fatty acids (SFAs) to monounsaturated fatty acids (MUFAs), has been suggested as a vulnerable target for selective elimination of cancer stem cells (CSCs). However, the clinical significance and physiological role of SCD1 in CSCs has not been well demonstrated. Here, we showed the clinical and biochemical relevance of blocking SCD1 to target CSCs by analyzing human colon cancer data from TCGA and through lipidomic profiling of CSCs with or without SCD1 inhibition using mass spectrometry. Positive associations between SCD1 expression and colorectal cancer patient clinical status and the expression of CSC-related genes (WNT and NOTCH signaling) were found based on TCGA data analysis. Lipidomic profiling of CSCs and bulk cancer cells (BCCs) using mass spectrometry revealed that colon CSCs contained a distinctive lipid profile, with higher free MUFA and lower free SFA levels than in BCCs, suggesting that enhanced SCD1 activity generates MUFAs that may support WNT signaling in CSCs. In addition, all identified phosphatidyl-ethanolamine-containing MUFAs were found at higher levels in CSCs. Interestingly, we observed lower phosphatidyl-serine (18:1/18:0), phosphatidyl-choline (PC; p-18:0/18:1)), and sphingomyelin (SM; d18:1/20:0 or d16:1/22:0) levels in CSCs than in BCCs. Of those, SCD1 inhibition, which efficiently diminished free MUFA levels, increased those specific PC and SM and MUFAs in CSCs promptly. These results suggest that these specific lipid composition is critical for CSC stem cell maintenance. In addition, not only free MUFAs, which are known to be required for WNT signaling, but also other phospholipids, such as SM, which are important for lipid raft formation, may mediate other cell signaling pathways that support CSC maintenance. Comparison of the lipidomic profiles of colon cancer cells with those of previously reported for glioma cells further demonstrated the tissue specific characteristics of lipid metabolism in CSCs.

Tumor exosome-based nanoparticles are efficient drug carriers for chemotherapy

Developing biomimetic nanoparticles without loss of the integrity of proteins remains a major challenge in cancer chemotherapy. Here, we develop a biocompatible tumor-cell-exocytosed exosome-biomimetic porous silicon nanoparticles (PSiNPs) as drug carrier for targeted cancer chemotherapy. Exosome-sheathed doxorubicin-loaded PSiNPs (DOX@E-PSiNPs), generated by exocytosis of the endocytosed DOX-loaded PSiNPs from tumor cells, exhibit enhanced tumor accumulation, extravasation from blood vessels and penetration into deep tumor parenchyma following intravenous administration. In addition, DOX@E-PSiNPs, regardless of their origin, possess significant cellular uptake and cytotoxicity in both bulk cancer cells and cancer stem cells (CSCs). These properties endow DOX@E-PSiNPs with great in vivo enrichment in total tumor cells and side population cells with features of CSCs, resulting in anticancer activity and CSCs reduction in subcutaneous, orthotopic and metastatic tumor models. These results provide a proof-of-concept for the use of exosome-biomimetic nanoparticles exocytosed from tumor cells as a promising drug carrier for efficient cancer chemotherapy.

Abstract 1032: Establishing an in vitro model of lipopolysaccharide-induced tumorospheres formation of prostate epithelial cells for drug screening

Abstract Tumorospheres forming assay not only was utilized to enrich cancer stem cell from bulk cancer cells, also was widely used to analyze the ability of clonogenic growth and self-renewal capability of cancer stem cells. Meanwhile, chronic inflammation-induced epithelial transformation has been documented in a broad range of cells. However, the effect of chronic inflammatory agent on tumorosphere formation has never been tested. In current study, the classic pro-inflammatory agent lipopolysaccharide was utilized to establish an in vitro model through inducing prostate tumoroshpere formation. Then, trichostatin A, a panel inhibitor of histone deacetylases, was tested in this model for its anti-tumor effect. The results showed that treatment with lipopolysaccharide stimulated prostate cancer DU145 and PC3 cells undergoing migration and invasion with decreased the ratio of CK8 and CK18 versus vimentin. It also induced tumorospheres formation in suspension culture with increased a panel of tumor stem cell markers transcription (e.g. CD44, α-intergrin, nestin etc) and promoted phosphorylation of Stat3 (p-Stat3) and pro-oncogene c-Myc expression in vitro. Treatment with trichostatin A showed to restrain the above lipopolysaccharide-induced EMT and tumorosphere formation with decreasing the level of p-Stat3, p-Erk, p-c-jun, c-Myc, CD44 and SOX-2. Finally, blocking Stat3 signaling pathway by treatment with trichostatin A and/or small molecule compound Stattic, an inhibitor of p-Stat3, abrogated LPS-induced cancer stem-like tumorosphere formation. Taken together, our data demonstrated that lipopolysaccharide induced cancer stem-like tumorospheres formation successfully, which could be served as a simple and easy handling in vitro model for anti-tumor drug screening. Citation Format: Jiajia Jiang, Xueqi Lian, Sijie Tang, Xiaohua Li. Establishing an in vitro model of lipopolysaccharide-induced tumorospheres formation of prostate epithelial cells for drug screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1032.

Disulfiram modulates ROS accumulation and overcomes synergistically cisplatin resistance in breast cancer cell lines

The chemotherapeutic agent cisplatin typically induces apoptosis by inhibiting the cell cycle. Cancer Stem Cells (CSCs), which are a proliferative quiescent and slowly-cycling cell population, are less sensitive and therefore frequently spared from toxic effects. Thus, it remains a priority to increase the sensitivity of CSCs to cisplatin-based chemotherapy, or to specifically target CSCs to improve the therapeutic outcome in breast cancer. Disulfiram (DSF) is a drug used clinically for alcoholism treatment that has displayed promising anti-cancer activity in vitro and in cancer xenografts in breast cancer. Our study provides evidence that DSF inhibits Aldehyde dehydrogenase (ALDH) enzyme activity, inhibits the expression of stemness-related transcription factors (Sox, Nanog, Oct) in CSC derived from breast cancer cell lines, and modulates intracellular reactive oxygen species (ROS) generation. Importantly, our research proved that ALDH + stem-like cells play important roles in the resistance to the conventional chemotherapeutic agent cisplatin. DSF enhances the cytotoxic effect of cisplatin through inhibiting the stemness and by overcoming cisplatin resistance of ALDH + stem-like cells. A quantitative measurement showed the synergistic effect of DSF and cisplatin. Further, we show that ALDH + cancer stem-like cells and ALDH- bulk cancer cells have different intrinsic ROS levels, what may explain differences in susceptibility to cisplatin treatment. Importantly, this difference is eliminated by DSF treatment making both cell types similarly susceptible for cytotoxic effects by cisplatin. These findings may influence chemotherapeutic treatment approaches in the future.

Inhibiting Wee1 and ATR kinases produces tumor-selective synthetic lethality and suppresses metastasis.

We used the cancer-intrinsic property of oncogene-induced DNA damage as the base for a conditional synthetic lethality approach. To target mechanisms important for cancer cell adaptation to genotoxic stress and thereby to achieve cancer cell-specific killing, we combined inhibition of the kinases ATR and Wee1. Wee1 regulates cell cycle progression, whereas ATR is an apical kinase in the DNA-damage response. In an orthotopic breast cancer model, tumor-selective synthetic lethality of the combination of bioavailable ATR and Wee1 inhibitors led to tumor remission and inhibited metastasis with minimal side effects. ATR and Wee1 inhibition had a higher synergistic effect in cancer stem cells than in bulk cancer cells, compensating for the lower sensitivity of cancer stem cells to the individual drugs. Mechanistically, the combination treatment caused cells with unrepaired or under-replicated DNA to enter mitosis leading to mitotic catastrophe. As these inhibitors of ATR and Wee1 are already in phase I/II clinical trials, this knowledge could soon be translated into the clinic, especially as we showed that the combination treatment targets a wide range of tumor cells. Particularly, the antimetastatic effect of combined Wee1/ATR inhibition and the low toxicity of ATR inhibitors compared with Chk1 inhibitors have great clinical potential.

Cancer Stem Cells: Root of the Evil

Cancer stem cells (CSCs) have been one of the most attractive research areas over the last two decades due to their important roles in aggressive tumor behaviors. Although CSCs are usually a small subpopulation of tumors (less than 0.1%), these cells determine the fate of cancer patients because of their roles in poor prognoses. Accumulating evidence has shown that CSCs are the major responsible cell population in tumor development, growth, metastasis, and therapy resistance. The self-renewal and differentiation capacity of CSCs contribute to the initiation and maintenance of tumor growth. Several reports indicate that CSCs share numerous molecular characteristics with mesenchymal cells, so CSCs are accepted as leading players in metastasis. In addition, these cells possess a higher intrinsic resistance to chemotherapies and radiotherapies than bulk cancer cells. Therefore, therapeutic approaches in recent years have focused on effectively targeting CSCs. Here, we have reviewed the current literature on the resistant mechanisms of CSCs, their roles in metastasis, and the roles of non-coding RNAs in the regulation of aggressive CSC characteristics and novel therapy approaches against CSCs.

High-CLDN4 ESCC cells harbor stem-like properties and indicate for poor concurrent chemoradiation therapy response in esophageal squamous cell carcinoma.

Background:Esophageal squamous cell carcinoma (ESCC) is the major type of esophageal cancer in Asia and demonstrates poor survival rates following a therapeutic regimen.Methods:Cancer stem cells (CSCs) are responsible for tumor initiation, progression, and treatment failure in cancers. Therefore, identification and characterization of CSCs may help to improve clinical outcomes for ESCC patients. Tumor sphere formation assay are performed to isolate cancer stem-like ESCC cells. QRT-PCR, tumor initiation, metastasis, CCRT treatment are used to evaluate ESCC cells’ stemness properties in vitro and in vivo.Results:The authors’ data demonstrates that cancer stem-like ESCC cells harbored stemness characteristics including self-renewal, differentiation, and transdifferentiation, and possess tumor initiation, metastasis, and treatment inefficiency properties. For the identification of useful biomarkers of cancer stem-like ESCC cells, the authors further identified that CLDN4 was upregulated in cancer stem-like ESCC cells when compared with bulk cancer cells. High-CLDN4 cells harbored stemness and cisplatin/concurrent chemoradiation therapy (CCRT) resistance properties and a high level of CLDN4 was correlated with poor prognosis and poor CCRT response in ESCC patients. Importantly, thiamine tetrahydrofurfuryl disulfide (TTFD) decreased CLDN4 and attenuated stemness in ESCC cells, and TTFD combined with CCRT improved CCRT response in vivo.Conclusions:CLDN4 was suggested as prognostic and a CCRT response indicator for ESCC patients. TTFD combined with CCRT has potential to improve ESCC patient’s clinical outcomes in the future.

A versatile polyion complex can intelligently respond to a tumor microenvironment to eliminate tumor stem cells for enhanced lung cancer targeted therapy.

Poor prognosis in lung cancer has been proved to be associated with the presence of lung cancer stem cells (LCSCs). Similar to bulk cancer cells and always existing in the interior of a solid tumor, there are also insurmountable barriers for the elimination of CSCs. To overcome these drawbacks, a versatile polyion complex was rationally designed, which can respond to a tumor microenvironment and exhibits a size-variable property, which allows it to possess remarkable tumor penetration capability and to accumulate around LCSCs. Protein tyrosine kinase 7 (PTK7) antibody mediated active targetability can facilitate the cellular uptake of triphenylphosphine-docetaxel (TD) and microRNA-31(miR-31) and the breakage of the disulfide bond can also enhance intracellular drug release. TD possesses a favorable apoptosis-inducing effect via a mitochondria pathway, while miR-31 could significantly regulate the MET-PI3K-Akt signaling pathway to exert the capability to eliminate LCSCs. APSP/HA might support new insights into LCSC eradiation in cancer management.

Therapeutic targeting of lipid synthesis metabolism for selective elimination of cancer stem cells.

Cancer stem cells (CSCs) are believed to have an essential role in tumor resistance and metastasis; however, no therapeutic strategy for the selective elimination of CSCs has been established. Recently, several studies have shown that the metabolic regulation for ATP synthesis and biological building block generation in CSCs are different from that in bulk cancer cells and rather similar to that in normal tissue stem cells. To take advantage of this difference for CSC elimination therapy, many studies have tested the effect of blocking these metabolism. Two specific processes for lipid biosynthesis, i.e., fatty acid unsaturation and cholesterol biosynthesis, have been shown to be very effective and selective for CSC targets. In this review, lipid metabolism specific to CSCs are summarized. In addition, how monounsaturated fatty acid and cholesterol synthesis may contribute to CSC maintenance are discussed. Specifically, the molecular mechanism required for lipid synthesis and essential for stem cell biology is highlighted. The limit and preview of the lipid metabolism targeting for CSCs are also discussed.

Single-cell RNA-seq analysis reveals the platinum resistance gene COX7B and the surrogate marker CD63.

Cancers acquire resistance to systemic treatment with platinum‐based chemotherapy (eg, cisplatin [CDDP]) as a result of a dynamic intratumoral heterogeneity (ITH) and clonal repopulation. However, little is known about the influence of chemotherapy on ITH at the single‐cell level. Here, mapping the transcriptome of cancers treated with CDDP by scRNA‐seq, we uncovered a novel gene, COX7B, associated with platinum‐resistance, and surrogate marker, CD63. Knockdown of COX7B in cancer cells decreased the sensitivity of CDDP whereas overexpression recovered the sensitivity of CDDP. Low COX7B levels correlated with higher mortality rates in patients with various types of cancer and were significantly associated with poor response to chemotherapy in urinary bladder cancer. Tumor samples from patients, who underwent CDDP therapy, showed decreased COX7B protein levels after the treatment. Analyzing scRNA‐seq data from platinum‐naïve cancer cells demonstrated a low‐COX7B subclone that could be sorted out from bulk cancer cells by assaying CD63. This low‐COX7B subclone behaved as cells with acquired platinum‐resistance when challenged to CDDP. Our results offer a new transcriptome landscape of platinum‐resistance that provides valuable insights into chemosensitivity and drug resistance in cancers, and we identify a novel platinum resistance gene, COX7B, and a surrogate marker, CD63.

Hypoxia-inducible factor 1-dependent expression of adenosine receptor 2B promotes breast cancer stem cell enrichment

Breast cancer stem cells (BCSCs), which are characterized by a capacity for unlimited self-renewal and for generation of the bulk cancer cell population, play a critical role in cancer relapse and metastasis. Hypoxia is a common feature of the cancer microenvironment that stimulates the specification and maintenance of BCSCs. In this study, we found that hypoxia increased expression of adenosine receptor 2B (A2BR) in human breast cancer cells through the transcriptional activity of hypoxia-inducible factor 1. The binding of adenosine to A2BR promoted BCSC enrichment by activating protein kinase C-δ, which phosphorylated and activated the transcription factor STAT3, leading to increased expression of interleukin 6 and NANOG, two key mediators of the BCSC phenotype. Genetic or pharmacological inhibition of A2BR expression or activity decreased hypoxia- or adenosine-induced BCSC enrichment in vitro, and dramatically impaired tumor initiation and lung metastasis after implantation of MDA-MB-231 human breast cancer cells into the mammary fat pad of immunodeficient mice. These data provide evidence that targeting A2BR might be an effective strategy to eradicate BCSCs.