Comparison of tumor biology of two distinct cell sub-populations in lung cancer stem cells

Exosomal lncRNA Mir100hg from lung cancer stem cells activates H3K14 lactylation to enhance metastatic activity in non-stem lung cancer cells

The mean survival of metastatic lung adenocarcinoma is less than 1 year, highlighting the urgent need to understand the mechanisms underlying its high mortality rate. The role of Extracellular vesicles (EVs) in facilitating the interactions between cancer cells and the metastatic microenvironment has garnered increasing attention. Previous studies on the role of EVs in metastasis have been primarily focused on cancer cell-derived EVs in modulating the functions of stromal cells. However, whether cancer stem cells (CSCs) can alter the metastatic properties of non-CSC cells, and whether EV crosstalk can mediate such interaction, have not been demonstrated prior to this report. In the present study, we integrated multi-omics sequencing and public database analysis with experimental validation to demonstrate, for the first time, the exosomal Mir100hg, derived from CSCs, could enhance the metastatic potential of non-CSCs both in vitro and in vivo. Mechanistically, HNRNPF and HNRNPA2B1 directly binds to Mir100hg, facilitating its trafficking via exosomes to non-CSCs. In non-CSCs, Mir100hg upregulates ALDOA expression, subsequently leading to elevated lactate production. Consequently, the increased lactate levels enhance H3K14 lactylation by 2.5-fold and promote the transcription of 169 metastasis-related genes. This cascade of events ultimately results in enhanced ALDOA-driven glycolysis and histone lactylation-mediated metastatic potential of non-CSC lung cancer cells. We have delineated a complex regulatory network utilized by CSCs to transfer their high metastatic activity to non-CSCs through exosomal Mir100hg, providing new mechanistic insights into the communication between these two heterogeneous tumor cell populations. These mechanistic insights provide novel therapeutic targets for metastatic lung cancer, including HNRNPF/HNRNPA2B1-mediated Mir100hg trafficking and the histone lactylation pathway, advancing our understanding of CSC-mediated metastasis while suggesting promising strategies for clinical intervention.

Exosomal lncRNA Mir100hg derived from cancer stem cells enhance glycolysis and promote metastasis of melanoma through miR-16-5p and miR-23a-3p

Increasing evidence demonstrate that the significant role of long non-coding RNA (lncRNA) in metastasis and the remodeling of the tumor microenvironment. However, the precise mechanisms of lncRNAs in cancer metastasis are still poorly understood. The function of lncRNA-Mir100hg in melanoma and its involvement in mediating communication between tumor stem cells and non-stemness tumor cells remains unknown. We found that Mir100hg is upregulated in melanoma stem cells (CSCs) known as OLSD. Furthermore, Mir100hg can be transferred from OLSD to non-stem cancer cells (OL) through exosomes. Once Mir100hg enters OL cells, it operates through a competitive endogenous RNA (ceRNA) mechanism. It competes with microRNAs (miR-16-5p and miR-23a-3p) by binding to them, thus preventing these miRNAs from targeting their mRNAs. As a result, the expression of glycolysis-related mRNA was restored. This ultimately enhances the metastatic capability of OL cells. In summary, our study uncovers a network used by CSCs to transfer their high metastatic activity to non-stem cancer cells through the exosomal Mir100hg. This mechanism sheds new light on the communication between heterogeneous cancer cell populations in melanoma. Importantly, it provides novel insights into the role of lncRNAs in cancer metastasis and highlights the significance of the tumor microenvironment in facilitating metastasis.

Exosomal lncRNA Mir100hg derived from cancer stem cells enhance glycolysis and promote metastasis of lung adenocarcinoma through mircroRNA-15a-5p/31-5p

BACKGROUND

Exosomes are a new class of molecular entities in the metastatic microenvironment, which can mediate bidirectional communication between cells. While exosomes-mediated interactions between tumor cells and other cell populations in the tumor microenvironment have attracted most attention, little is known about the significance of exosomes in mediating the interaction between non-stemness cancer cells and cancer stem cells during cancer progression.

METHODS

The structure, sequence and downstream target miRNAs of lncRNA Mir100hg were predicted by online web resources. The bioinformatics prediction results were validated with experimental verification: exosome tracing, electron microscopy, Luciferase assay, metabolomics sequencing and mouse tail vein model of pulmonary metastasis. A complex regulatory network of "cancer stem cells-exosomal lncRNA-non-stem cancer cells" was constructed.

RESULTS

This study demonstrates firstly that lncRNA Mir100hg is upregulated in lung cancer stem cell LLC-SD (Lung cancer stem cells) and can be delivered to non-stemness cancer cells LLC (Lewis lung cancer cells) via exosomes. In LLC, Mir100hg targets miR-15a-5p and miR-31-5p which leads to the increase of the global glycolytic activity of lung cancer cells and consequently, the enhancement of their metastatic capability.

CONCLUSION

We delineated a complex regulatory network that utilized by cancer stem cells to transfer their high metastatic activity to the low-metastatic non-stemness cancer cells through exosomal Mir100hg, thereby providing new mechanistic insights into the communication between two heterogeneous tumor cells. Video Abstract.

HIF1α and HIF2α regulate non-small-cell lung cancer dedifferentiation via expression of Sox2 and Oct4 under hypoxic conditions

OBJECTIVE

To explore HIF1α and HIF2α regulate the dedifferentiation of lung cancer cells under hypoxic conditions through Sox2 and Oct4.

MATERIALS AND METHODS

HIF1α, HIF2α, Sox2 and Oct4 expression was analysed in lung cancer tissues. We analysed sphere formation by single-cell of differentiated lung cancer under hypoxia, and detected the expression of CD133, CD44, Sox2, Oct4, HIF1α and HIF2α. We knocked out HIF1α, HIF2α, Sox2 or Oct4 in cells, cultured the cells under hypoxic conditions and detected CD133 and CD44 using western blotting. We also detected the apoptosis rate of cells with HIF1α, HIF2α, Sox2 or Oct4 knockout.

RESULTS

There was more sphere formation of differentiated lung cancer cells under hypoxic conditions than of control cells under normoxic conditions. These newly formed spheres highly expressed CD133 and CD44. TCGA database showed high expression of HIF1α and HIF2α in lung cancer tissues. After knocking out HIF1α and HIF2α, the expression of Sox2, Oct4, CD133 and CD44 decreased significantly, and after knocking out Sox2 or Oct4, the expression of CD133 and CD44 decreased.

CONCLUSION

HIF1α and HIF2α regulate non-small-cell lung cancer dedifferentiation through Sox2 and Oct4 under hypoxic conditions.

Exosomal microRNA-4535 of Melanoma Stem Cells Promotes Metastasis by Inhibiting Autophagy Pathway

High mortality rate and poor survival in melanoma are associated with efficient metastatic colonization. The underlying mechanisms remain elusive. Elucidating the role of exosomes in mediating the interactions between cancer cells and the metastatic microenvironment has been focused on cancer cell derived exosomes in modulating the functions of stromal cells. Whether cancer stem cells (CSCs) can modify the metastatic properties of non-CSC cells, and whether exosomal crosstalk plays a role have not been demonstrated prior to this report. In this study, a paired M14 melanoma derivative cell line, i.e., melanoma parental cell (MPC) and its CSC derivative cell line melanoma stem cell (MSC) were employed. We demonstrated that exosomal crosstalk betwen MSCs and non-CSC MPCs is a new mechanism that underlies melanoma metastasis. Low metastatic melanoma cells (MPCs) can acquire the "metastatic power" from highly metastatic melanoma CSCs (MSCs). We illustrated an uncharacterized microRNA, miR-4535 in mediating such exosomal crosstalk. MSCs deliver its exosomal miR-4535 to the targeted MPCs. Upon entering MPCs, miR-4535 augments metastatic colonization of MPCs by inactivating the autophagy pathway.

Extracellular vesicles microRNA-592 of melanoma stem cells promotes metastasis through activation of MAPK/ERK signaling pathway by targeting PTPN7 in non-stemness melanoma cells

Melanoma, one of the most aggressive malignancies, its high mortality and low survival rates are associated with effective metastatic colonization. Melanoma metastasis hinges on the bidirectional cell-cell communication within the complex metastatic microenvironments (MME). Extracellular vesicles (EVs) are recognized as a new class of molecular mediator in MME programing. Published studies show that melanoma EVs can educate MME stromal cells to acquire the pro-metastatic phenotype to enhance metastatic colonization. Whether EVs can mediate the interactions between heterogenous cancer cells within the MME that alter the course of metastasis has not been investigated at the mechanistic level. In this study, melanoma parental cells (MPCs) and paired derivative cancer stem cell line melanoma stem cells (MSCs) that were derived from melanoma cell line M14 were used. We demonstrate that the EVs-mediated crosstalk between the MSCs and the MPCs is a novel mechanism for melanoma metastasis. We characterized miR-592, a relatively novel microRNA of prognostic potential, in mediation of such intercellular crosstalk. EVs can encapsulate and deliver miR-592 to target MPCs. Upon entering, miR-592 inhibits the expression of its gene target protein tyrosine phosphatase non-receptor type7 (PTPN7), a phosphatase targeting MAPKs. This leads to the relief of the inhibitory effect of PTPN7 on MAPK/ERK signaling and consequently the augmentation of metastatic colonization of MPCs. Thus, via the extracellular vesicle miR-592/PTPN7/MAPK axis, melanoma-CSCs can transfer their metastatic ability to the low-metastatic non-CSC melanoma cells.

Melanoma stem cells promote metastasis via exosomal miR-1268a inactivation of autophagy

Background

Metastatic melanoma has a high mortality rate and poor survival. This is associated with efficient metastatic colonization, but the underlying mechanisms remain elusive. Communication between cancer stem cells (CSCs) and cancer cells plays an important role in metastatic dissemination. Whether cancer stem cells can alter the metastatic properties of non-CSC cells; and whether exosomal crosstalk can mediate such interaction, have not been demonstrated in melanoma prior to this report.

Results

The results revealed that exosomes secreted by highly metastatic melanoma CSCs (OL-SCs) promoted the invasiveness of the low metastatic melanoma cells (OL) and accelerated metastatic progression. miR-1268a was up-regulated in cells and exosomes of OL-SCs. Moreover, OL-SCs-derived exosomal miR-1268a, upon taking up by OL cells, promoted the metastatic colonization ability of OL cells in vitro and in vivo. In addition, the pro-metastatic activity of exosomal miR-1268a is achieved through inhibition of autophagy.

Conclusion

Our study demonstrates that OL cells can acquire the “metastatic ability” from OL-SCs cells. OL-SCs cells achieves this goal by utilizing its exosomes to deliver functional miRNAs, such as miR-1268a, to the targeted OL cells which in turn augments metastatic colonization by inactivating the autophagy pathway in OL cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40659-022-00397-z.

Sec23a inhibits the self-renewal of melanoma cancer stem cells via inactivation of ER-phagy

BACKGROUND

The genesis and developments of solid tumors, analogous to the renewal of healthy tissues, are driven by a subpopulation of dedicated stem cells, known as cancer stem cells (CSCs), that exhibit long-term clonal repopulation and self-renewal capacity. CSCs may regulate tumor initiation, growth, dormancy, metastasis, recurrence and chemoresistance. While autophagy has been proposed as a regulator of the stemness of CSCs, the underlying mechanisms requires further elucidation.

METHODS

The CSC component in human melanoma cell lines M14 and A375 was isolated and purified by repetitive enrichments for cells that consistently display anchorage-independent spheroid growth. The stemness properties of the CSCs were confirmed in vitro by the expressions of stemness marker genes, the single-cell cloning assay and the serial spheroid formation assay. Subcutaneous tumor transplantation assay in BALB/c nude mice was performed to test the stemness properties of the CSCs in vivo. The autophagic activity was confirmed by the protein level of LC3 and P62, mRFP-LC3B punta and cytoplasmic accumulation of autolysosomes. The morphology of ER was detected with transmission electron microscopy.

RESULTS

In the present study, by employing stable CSC cell lines derived from human melanoma cell lines M14 and A375, we show for the first time that Sec23a inhibits the self-renewal of melanoma CSCs via inactivation of ER-phagy. Mechanistically, inhibition of Sec23a reduces ER stress and consequently FAM134B-induced ER-phagy. Furthermore, TCGA data mining and analysis show that Sec23a is a favorable diagnostic and prognostic marker for human skin cutaneous melanoma.

CONCLUSION

This study has elucidated a new mechanism underlying the regulation of autophagy on stemness, i.e. CSCs can exploit the SEC23A/ER-stress/FAM134B/ER-phagy axis for the self-renewal. These observations provide new ideas for exploration of the regulatory network of CSC self-renewal to develop CSCs-based therapy strategies for malignant tumors. Video Abstract.

Three dimensional in vitro culture systems in anticancer drug discovery targeted on cancer stem cells

Worldwide, tumors are one of the most common causes of death. Every year 3.7 million new cases occur in Europe and more than 1.9 million patients die (WHO data). Most of the fields of research are focused on developing new therapeutic strategies that will be effective in eliminating the tumor, preventing its remission, and avoiding or reducing the side effects of therapy. In the past, generally classical 2D cell cultures or immunodeficient animal models had been used to cultivate and test drugs on human cancer cell lines. Nowadays, there are increasing interests in three-dimensional (3D) cell cultures, a method with significant differences from flat cultured cells, both considering gene expressions and cell-cell interactions. Various evidence suggests that high tumorigenic properties might be dependent on the occurrence of a small cell population, pointed out to be responsible for metastasis and recurrence. This population is called cancer stem cells (CSCs), hinted to have a lot of similarities with normal stem cells. CSCs are the main reason for chemotherapy failure as well as multi-drug resistance (MDR). CSCs can also interact through the cytokine network, with other cells like the macrophages of the inflammatory system. The big advantage of a 3D culture is the possibility to isolate and investigate the CSCs population surrounded by its environment. This article aims to sum up known 3D cell cultures, especially in the field of CSCs research due to the importance of the tumor's environment on stem cell's markers expression and their development.

The mitochondrial fission factor FIS1 promotes stemness of human lung cancer stem cells via mitophagy

Mitophagy, a form of autophagy, plays a role in cancer development, progression and recurrence. Cancer stem cells (CSCs) also play a key role in these processes, although it not known whether mitophagy can regulate the stemness of CSCs. Here, we employed the A549-SD human non-small cell lung adenocarcinoma CSC model that we have developed and characterized to investigate the effect of mitophagy on the stemness of CSCs. We observed a positive relationship between mitophagic activity and the stemness of lung CSCs. At the mechanistic level, our results suggest that augmentation of mitophagy in lung CSCs can be induced by FIS1 through mitochondrial fission. In addition, we assessed the clinical relevance of FIS1 in lung adenocarcinoma using The Cancer Genome Atlas database. An elevation in FIS1, when observed together with other prognostic markers for lung cancer progression, was found to correlate with shorter overall survival.

Characteristics of the PI3K/AKT and MAPK/ERK pathways involved in the maintenance of self-renewal in lung cancer stem-like cells

Lung cancer is the leading cause of cancer-related mortality worldwide due to its early asymptomatic and late metastasis. While cancer stem cells (CSCs) may play a vital role in oncogenesis and development of lung cancer, mechanisms underlying CSCs self-renewal remain less clear. In the present study, we constructed a clinically relevant CSCs enrichment recognition model and evaluated the potential functions of phosphatidylinositol 3-kinase (PI3K)/AKT pathway (PI3K/AKT) and mitogen-activated protein kinases/extracellular signal-regulated kinase (MAPK/ERK) pathways in lung cancer via bioinformatic analysis, providing the basis for in depth mechanistic inquisition. Experimentally, we confirmed that PI3K/AKT pathway predominantly promotes proliferation through anti-apoptosis in lung adenocarcinoma cells, while MAPK/ERK pathway has an overwhelming superiority in regulating the proliferation in lung CSCs. Further, utilizing stemness score model, LLC-Symmetric Division (LLC-SD) cells and mouse orthotopic lung transplantation model, we elucidated an intricate cross-talk between the oncogenic pathway and the stem cell reprograming pathway that impact stem cell characteristics as well as cancer biology features of lung CSCs both in vitro and in vivo. In summary, our findings uncovered a new insight that PI3K/AKT and MAPK/ERK pathways as oncogenic signaling pathway and/or stem cell signaling pathway act distinctively and synergistically to regulate lung CSCs self-renewal.

Autophagy augments the self-renewal of lung cancer stem cells by the degradation of ubiquitinated p53

It has been postulated that cancer stem cells (CSCs) are involved in all aspects of human cancer, although the mechanisms governing the regulation of CSC self-renewal in the cancer state remain poorly defined. In the literature, both the pro- and anti-oncogenic activities of autophagy have been demonstrated and are context-dependent. Mounting evidence has shown augmentation of CSC stemness by autophagy, yet mechanistic characterization and understanding are lacking. In the present study, by generating stable human lung CSC cell lines with the wild-type TP53 (A549), as well as cell lines in which TP53 was deleted (H1229), we show, for the first time, that autophagy augments the stemness of lung CSCs by degrading ubiquitinated p53. Furthermore, Zeb1 is required for TP53 regulation of CSC self-renewal. Moreover, TCGA data mining and analysis show that Atg5 and Zeb1 are poor prognostic markers of lung cancer. In summary, this study has elucidated a new CSC-based mechanism underlying the oncogenic activity of autophagy and the tumor suppressor activity of p53 in cancer, i.e., CSCs can exploit the autophagy-p53-Zeb1 axis for self-renewal, oncogenesis, and progression.

Mechanisms of cancer stem cell therapy

Cancer stem cells (CSCs) are responsible for carcinogenesis and tumorigenesis and are involved in drug and radiation resistance, metastasis, tumor relapse and initiation. Remarkably, they have other abilities such as inheritance of self-renewal and de-differentiation. Hence, targeting CSCs is considered a potential anti-cancer therapeutic strategy. Recent advances in the identification of biomarkers to recognize CSCs and the development of new techniques to evaluate tumorigenic and carcinogenic roles of CSCs are instrumental to this approach. Elucidation of signaling pathways that regulate CSCs colony progression and drug resistance are critical in establishing effective targeted therapies. CSCs play a central key role in immunomodulation, immune evasion and effector immunity, which alters immune system balancing. These include mTOR, SHH, NOTCH and Wnt/β-catering in cancer progression. In this review article, we discuss the importance of these CSCs pathways in cancer therapy.

Cdh1 functions as an oncogene by inducing self-renewal of lung cancer stem-like cells via oncogenic pathways

The mortality rate of lung cancer remains the highest amongst all cancers despite of new therapeutic developments. While cancer stem cells (CSCs) may play a pivotal role in cancer, mechanisms underlying CSCs self-renewal and their relevance to cancer progression have not been clearly elucidated due to the lack of reliable and stable CSC cellular models. In the present study, we unveiled the novel oncogene function of cadherin 1 (Cdh1) via bioinformatic analysis in a broad spectrum of human cancers including lung adenocarcinoma (LUAD), adding a new dimension to the widely reported tumor suppressor function of Cdh1. Experimentally, we show for the first time that Cdh1 promotes the self-renewal of lung CSCs, consistent with its function in embryonic and normal stem cells. Using the LLC-Symmetric Division (LLC-SD) model, we have revealed an intricate cross-talk between the oncogenic pathway and stem cell pathway in which Cdh1 functions as an oncogene by promoting lung CSC renewal via the activation of the Phosphoinositide 3-kinase (PI3K) and inhibition of Mitogen-activated protein kinase (MAPK) pathways, respectively. In summary, this study has provided evidence demonstrating effective utilization of the normal stem cell renewal mechanisms by CSCs to promote oncogenesis and progression.

Transcriptional Activation of Gstp1 by MEK/ERK Signaling Confers Chemo-Resistance to Cisplatin in Lung Cancer Stem Cells

Lung cancer management remains a challenge due to its asymptomatic and late presentation when it is metastatic. The clinical response to the first-line platinum-based chemotherapy in patients with advanced lung cancer is disappointing due to the development of chemoresistance. Chemoresistance is a complex phenomenon. Mechanistic research using experimental models has yielded limited clinical results to help increase understanding for overcoming resistance. While the role of lung CSCs in conferring multidrug resistance has been postulated, experimental evidence remains associative and lacks in depth mechanistic inquisition. In the present study, using mouse and human lung adenocarcinoma cell lines and their respective paired CSC derivative cell lines that we generated, we identified cancer stem cell component of lung adenocarcinoma as the source that confers multidrug resistance phenotype. Mechanistically, Gstp1 confers cisplatin resistance in mouse and human lung CSC models, both in vitro and in vivo. Further, transcriptional activation of Gstp1 expression by MEK/ERK signaling underlies cisplatin resistance in lung CSC cells. Moreover, we show that GSTP1 expression is a poor diagnostic and prognostic marker for human lung adenocarcinoma, thus is of high clinical relevance. Taken together, we have provided mechanistic understanding of the lung CSC in mediating chemoresistance.

Asymmetric Division Gene Neurl2 Mediates Twist2 Regulation of Self-Renewal of Mouse Lewis Lung Cancer Stem Cells

Cancer stem cells (CSCs) play an important role in tumor development. While Epithelial-Mesenchymal Transition (EMT) has been shown to promote CSC self-renewal, underlying mechanisms are unclear. Here we identified and characterized the requirement of twist2, the EMT transcription factor, for the regulation of self-renewal thus stemness of mouse Lewis lung CSCs both in vitro and in vivo. Further, we elucidated the role of neurl2, an asymmetric division gene for normal stem cells, in mediating the self-renewal promoting activity of twist2. Moreover, analysis of TCGA showed a positive correlation between the expression of twist2 and the development of lung adenocarcinoma, and a negative correlation between neurl2 and lung adenocarcinoma development. In summary, our study provides a new mechanistic insight of regulation of CSC self-renewal by EMT.

Nr5a2 promotes cancer stem cell properties and tumorigenesis in nonsmall cell lung cancer by regulating Nanog

Lung cancer has the highest mortality rate due to late diagnosis and high incidence of metastasis. Cancer stem cells (CSCs) are a subgroup of cancer cells with self‐renewal capability similar to that of normal stem cells (NSCs). While CSCs may play an important role in cancer progression, mechanisms underlying CSC self‐renewal and the relationship between self‐renewal of the NSCs and CSCs remain elusive. The orphan nuclear receptor Nr5a2 is a transcriptional factor, and a regulator of stemness of embryonic stem cells and induced pluripotent stem cells. However, whether Nr5a2 regulates the self‐renewal of lung CSCs is unknown. Here, we showed the diagnostic and prognostic values of elevated Nr5a2 expression in human lung cancer. We generated the mouse LLC‐SD lung carcinoma CSC cellular model in which Nr5a2 expression was enhanced. Using the LLC‐SD model, through transient and stable siRNA interference of Nr5a2 expression, we provided convincing evidence for a regulatory role of Nr5a2 in the maintenance of lung CSC self‐renewal and stem cell properties in vitro. Further, using the syngeneic and orthotopic lung transplantation model, we elucidated augmented cancer biological properties associated with Nr5a2 promotion of LLC‐SD self‐renewal. More importantly, we revealed that Nr5a2’s regulatory role in promoting LLC‐SD self‐renewal is mediated by transcriptional activation of its direct target Nanog. Taken together, in this study, we have provided convincing evidence in vitro and in vivo demonstrating that Nr5a2 can induce lung CSC properties and promote tumorigenesis and progression through transcriptional up‐regulation of Nanog.

Zeb1 Regulates the Symmetric Division of Mouse Lewis Lung Carcinoma Stem Cells through Numb mediated by miR-31

Symmetric cell division (SD) and asymmetric cell division (ASD) were the unique characteristics of stem cells and the mechanisms underlying stem cell renewal. While recent studies have identified the presence of SD and ASD in lung cancer stem cells (CSCs), the mechanisms regulating SD and ASD in cancer state have not been elucidated, mostly due to the lack of stable cellular models of SD and ASD in CSC research. In this study, the interaction between Zeb1, an Epithelial-Mesenchymal Transition (EMT) factor shown to regulate CSCs self-renew, and Numb, which regulates SD and ASD in the normal neural stem cell was investigated using the stable mouse Lewis lung adenocarcinoma SD (LLC-SD) and ASD (LLC-ASD) lines established from our previous study. The most significant finding derived from this line of research is that we have identified and molecularly ordered the axis of Zeb1-miR-31-Numb that regulates the SD, a mechanism of CSC self-renewal that has not been previously described. More specifically, the expression of Zeb1 and Numb were both significantly higher in LLC-SD than LLC-ASD cells. Silencing of Zeb1 or Numb expression lead to decreased ratio of SD and weakened single-cell cloning formation, tumor growth and tumor metastasis, respectively. The rescure experiments have molecularly ordered the regulation of Numb by Zeb1, indirectly mediated by miR-31. Moreover, we also provided preliminary evidence supporting the clinical relevance of our finding. In summary, our study provides a new insight for the self-renew of lung CSCs in which SD is regulated by the axis of Zeb1-miR-31-Numb.

Neuralized1a regulates asymmetric division in mouse Lewis lung carcinoma cells

Asymmetric division (ASD), the unique characteristic of normal stem cells, is regarded as a stemness marker when applied to the study of cancer stem cells (CSCs). However, the role of ASD in the self-renewal of CSCs and its regulation remain largely unknown. Here, we first established a mouse Lewis lung carcinoma CSC cell line that could undergo asymmetric division (LLC-ASD cells) derived from the parental mouse Lewis lung carcinoma cancer cells (LLC-Parental cells). In vitro assessment of stemness by RT-qPCR and western blot analysis of stem cell markers, clonogenic assay (p < 0.001), single cell spheroid formation assay (p < 0.05) and 96-well-plate single-cell cloning assay (p < 0.01) indicated that the LLC-ASD cells exhibited stronger stemness features in comparison to the LLC-Parental cells. In vivo, tumorigenicity of LLC-ASD cells, transplanted subcutaneously to the nude mice, was increased compared to that of LLC-parental cells (p < 0.05). Further, Neuralized1a, a regulator of ASD in normal stem cells, was highly expressed in the LLC-ASD cells. Silencing Neuralized1a expression in LLC-ASD cells by siRNA weakened the stemness features measured by the in vitro assays listed above (p < 0.05). The tumorigenic ability was also decreased in the nude mice upon Neuralized1a silencing (p < 0.05). Collectively, the present study suggests that Neuralized1a regulates the stemness of LLC-ASD cells which could be the new marker and therapeutic target of CSCs.