Epiregulin increases stemness-associated genes expression and promotes chemoresistance of non-small cell lung cancer via ERK signaling

Background

Chemoresistance often causes the failure of treatment and death of patients with advanced non-small-cell lung cancer. However, there is still no resistance genes signature and available enriched signaling derived from a comprehensive RNA-Seq data analysis of lung cancer patients that could act as a therapeutic target to re-sensitize the acquired resistant cancer cells to chemo-drugs. Hence, in this study, we aimed to identify the resistance signature for clinical lung cancer patients and explore the regulatory mechanism.

Method

Analysis of RNA-Seq data from clinical lung cancer patients was conducted in R studio to identify the resistance signature. The resistance signature was validated by survival time of lung cancer patients and qPCR in chemo-resistant cells. Cytokine application, small-interfering RNA and pharmacological inhibition approaches were applied to characterize the function and molecular mechanism of EREG and downstream signaling in chemoresistance regulation via stemness.

Results

The RTK and vitamin D signaling were enriched among resistance genes, where 6 genes were validated as resistance signature and associated with poor survival in patients. EREG/ERK signaling was activated by chemo-drugs in NSCLC cells. EREG protein promoted the NSCLC resistance to chemo-drugs by increasing stemness genes expression. Additionally, inhibition of EREG/ErbB had downregulated ERK signaling, resulting in decreased expression of stemness-associated genes and subsequently re-sensitized the resistant NSCLC cells and spheres to chemo-drugs.

Conclusions

These findings revealed 6 resistance genes signature and proved that EREG/ErbB regulated the stemness to maintain chemoresistance of NSCLC via ERK signaling. Therefore, targeting EREG/ErbB might significantly and effectively resolve the chemoresistance issue.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02859-3.

The role of PFKFB3 in maintaining colorectal cancer cell proliferation and stemness

Since generally confronting with the hypoxic and stressful microenvironment, cancer cells alter their glucose metabolism pattern to glycolysis to sustain the continuous proliferation and vigorous biological activities. Bifunctional 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2) isoform 3 (PFKFB3) functions as an effectively modulator of glycolysis and also participates in regulating angiogenesis, cell death and cell stemness. Meanwhile, PFKFB3 is highly expressed in a variety of cancer cells, and can be activated by several regulatory factors, such as hypoxia, inflammation and cellular signals. In colorectal cancer (CRC) cells, PFKFB3 not only has the property of high expression, but also probably relate to inflammation-cancer transformation. Recent studies indicate that PFKFB3 is involved in chemoradiotherapy resistance as well, such as breast cancer, endometrial cancer and CRC. Cancer stem cells (CSCs) are self-renewable cell types that contribute to oncogenesis, metastasis and relapse. Several studies indicate that CSCs utilize glycolysis to fulfill their energetic and biosynthetic demands in order to maintain rapid proliferation and adapt to the tumor microenvironment changes. In addition, elevated PFKFB3 has been reported to correlate with self-renewal and metastatic outgrowth in numerous kinds of CSCs. This review summarizes our current understanding of PFKFB3 roles in modulating cancer metabolism to maintain cell proliferation and stemness, and discusses its feasibility as a potential target for the discovery of antineoplastic agents, especially in CRC.

LINC00662 enhances cell progression and stemness in breast cancer by MiR-144-3p/SOX2 axis

BACKGROUND

Breast cancer (BC) is one of the most prevalent malignancies among women globally. Emerging evidence indicates that long non-coding RNAs (lncRNAs) are associated with BC carcinogenesis. In the current study, we explored the mechanism by which LINC00662 regulates BC.

METHODS

Quantitative real-time PCR (qRT-PCR) assessed RNA expressions while western blot for protein levels. Kaplan Meier analysis evaluated overall survival (OS). Cytoplasmic/nuclear fractionation, RNA binding protein immunoprecipitation (RIP) and luciferase reporter assays probed into the underlying molecular mechanism of LINC00662 in BC. Xenograft model was established to explore the influence of LINC00662 on BC progression in vivo. R square graphs were utilized to represent RNA relationships.

RESULTS

LINC00662 is overtly overexpressed in BC tissues and cell lines. LINC00662 knockdown hampers cell proliferation, migration, invasion and stemness. LINC00662 expression is negatively correlated with OS of BC patients. LINC00662 up-regulates SOX2 expression by competitively binding to miR-144-3p, thereby modulating BC cell progression. Xenograft experiments verified that LINC00662 promotes BC tumor growth and cell stemness in vivo.

CONCLUSION

LINC00662 enhances cell proliferation, migration, invasion and stemness in BC by targeting miR-144-3p/SOX2 axis. The findings in the present study suggested that LINC00662 could be a potential therapeutic target for BC treatment.

PAX9 reactivation by inhibiting DNA methyltransferase triggers antitumor effect in oral squamous cell carcinoma

Aberrant DNA hypermethylation is associated with oral carcinogenesis. Procaine, a local anesthetic, is a DNA methyltransferase (DNMT) inhibitor that activates anticancer mechanisms. However, its effect on silenced tumor suppressor gene (TSG) activation and its biological role in oral squamous cell carcinoma (OSCC) remain unknown. Here, we report procaine inhibited DNA methylation by suppressing DNMT activity and increased the expression of PAX9, a differentiation gene in OSCC cells. Interestingly, the reactivation of PAX9 by procaine found to inhibit cell growth and trigger apoptosis in OSCC in vitro and in vivo. Likely, the enhanced PAX9 expression after exposure to procaine controls stemness and differentiation through the autophagy-dependent pathway in OSCC cells. PAX9 inhibition abrogated procaine-induced apoptosis, autophagy, and inhibition of stemness. In OSCC cells, procaine improved anticancer drug sensitivity through PAX9, and its deficiency significantly blunted the anticancer drug sensitivity mediated by procaine. Additionally, NRF2 activation by procaine facilitated the antitumor response of PAX9, and pharmacological inhibition of NRF2 by ML385 reduced death and prevented the decrease in the orosphere-forming potential of OSCC cells. Furthermore, procaine promoted antitumor activity in FaDu xenografts in athymic nude mice, and immunohistochemistry data showed that PAX9 expression was significantly enhanced in the procaine group compared to the vehicle control. In conclusion, PAX9 reactivation in response to DNMT inhibition could trigger a potent antitumor mechanism to provide a new therapeutic strategy for OSCC.

miR-600 promotes ovarian cancer cells stemness, proliferation and metastasis via targeting KLF9

Previous studies have revealed that miRNAs participate in the pathogenesis of ovarian cancer; however, whether miR-600 is also involved remains unclear. In this study, we aimed to investigated the role of miR-600 in ovarian cancer progression. Here, miR-600 expression was significantly upregulated in ovarian cancer tissues and stem cells. Functional studies showed that miR-600 promoted ovarian cancer cell stemness, proliferation and metastasis. Mechanistic studies revealed that Kruppel like factor 9 (KLF9) was indicated as the target of miR-600. The luciferase reporter assay suggested that miR-600 directly bound to the 3'-untranslated region of KLF9. Additionally, miR-600 expression was negatively associated with KLF9 expression in human ovarian cancer tissues. Si-KLF9 partially abolished the discrepancy of self-renewal, growth and metastasis capacity between miR-600 knockdown ovarian cancer cells and control cells. In conclusion, our results suggest that miR-600 promotes ovarian cancer cell stemness, proliferation and metastasis via directly downregulating KLF9, and impairing miR-600 levels may be a new treatment strategy for ovarian cancer in the future.

Zuogui pills maintain the stemness of oogonial stem cells and alleviate cyclophosphamide-induced ovarian aging through Notch signaling pathway

BACKGROUND

Zuogui pills (ZGP), a classical prescription of traditional Chinese medicine, have been widely used in the treatment of ovarian aging. Previous studies have demonstrated its efficacy on protecting ovarian aging, and the mechanisms were mostly relevant to inhibiting the apoptosis of follicles and activating the primordial follicles. However, whether ZGP could stimulate the oogonial stem cells (OSCs) to refresh the follicle pool remains poorly understood.

PURPOSE

To investigate the effects of ZGP on the stemness of OSCs in cyclophosphamide (Cy)-induced ovarian aging.

STUDY DESIGN AND METHODS

Female Sprague-Dawley (SD) rats were randomly divided into 8 groups: control group, model group, ZGP groups (low / high dose groups), estradiol valerate (EV) groups (low / high dose groups), DAPT group and DAPT+ZGP-L group. After modeling with Cy, the ZGP groups and EV groups were treated with ZGP and EV for 8 weeks respectively. Meanwhile, the DAPT groups were treated with DAPT twice a week. Additionally, OSCs were also isolated after modeling, and then treated with drug serum containing ZGP or EV. Ovarian volume and the ratio of weight of total ovaries to the body weight were measured. The serum hormones were measured by ELISA. Quantities and location of OSCs in ovaries were detected by flow cytometry and immunofluorescence. Cell viability was measured by CCK8. And OSCs were identified by immunofluorescence. Biomarkers of germ cells, stem cells and associated to differentiation and meiosis were detected by qPCR and western blot. Proteins in Notch signaling pathway were detected by western blot and immunofluorescence.

RESULTS

After treating with ZGP, ovarian volume and the ratio of weight of total ovaries to the body weight increased. ZGP could increase serum AMH and E2 level and decrease serum FSH level. Quantities and cell viability of OSCs increased after ZGP treatment in vivo and in vitro. In addition, treatment with ZGP could increase not only the expression of MVH, Oct4 and DAZL, but also the expression of ZP1 and ZP2. Furthermore, ZGP could up-regulate the expression of Notch intracellular domain (NICD), HES1 and HES5. After blocking the Notch signaling pathway, ZGP could increase not only the expression of NICD, HES1 and HES5, but also the expression of MVH, Oct4, DAZL, ZP1 and ZP3.

CONCLUSION

In conclusion, the mechanism of ZGP on treating ovarian aging may be relevant to maintain the stemness of OSCs by up-regulating Notch signaling pathway, which added the mechanism of ZGP on the perspective of OSCs at first time.

Integrated analysis of single-cell and bulk RNA sequencing data reveals a pan-cancer stemness signature predicting immunotherapy response

BACKGROUND

Although immune checkpoint inhibitor (ICI) is regarded as a breakthrough in cancer therapy, only a limited fraction of patients benefit from it. Cancer stemness can be the potential culprit in ICI resistance, but direct clinical evidence is lacking.

METHODS

Publicly available scRNA-Seq datasets derived from ICI-treated patients were collected and analyzed to elucidate the association between cancer stemness and ICI response. A novel stemness signature (Stem.Sig) was developed and validated using large-scale pan-cancer data, including 34 scRNA-Seq datasets, The Cancer Genome Atlas (TCGA) pan-cancer cohort, and 10 ICI transcriptomic cohorts. The therapeutic value of Stem.Sig genes was further explored using 17 CRISPR datasets that screened potential immunotherapy targets.

RESULTS

Cancer stemness, as evaluated by CytoTRACE, was found to be significantly associated with ICI resistance in melanoma and basal cell carcinoma (both P < 0.001). Significantly negative association was found between Stem.Sig and anti-tumor immunity, while positive correlations were detected between Stem.Sig and intra-tumoral heterogenicity (ITH) / total mutational burden (TMB). Based on this signature, machine learning model predicted ICI response with an AUC of 0.71 in both validation and testing set. Remarkably, compared with previous well-established signatures, Stem.Sig achieved better predictive performance across multiple cancers. Moreover, we generated a gene list ranked by the average effect of each gene to enhance tumor immune response after genetic knockout across different CRISPR datasets. Then we matched Stem.Sig to this gene list and found Stem.Sig significantly enriched 3% top-ranked genes from the list (P = 0.03), including EMC3, BECN1, VPS35, PCBP2, VPS29, PSMF1, GCLC, KXD1, SPRR1B, PTMA, YBX1, CYP27B1, NACA, PPP1CA, TCEB2, PIGC, NR0B2, PEX13, SERF2, and ZBTB43, which were potential therapeutic targets.

CONCLUSIONS

We revealed a robust link between cancer stemness and immunotherapy resistance and developed a promising signature, Stem.Sig, which showed increased performance in comparison to other signatures regarding ICI response prediction. This signature could serve as a competitive tool for patient selection of immunotherapy. Meanwhile, our study potentially paves the way for overcoming immune resistance by targeting stemness-associated genes.

Histone methyltransferase KMT2D cooperates with MEF2A to promote the stem-like properties of oral squamous cell carcinoma

Background

Epigenetic reprogramming is involved in multiple steps of human cancer evolution and is mediated by a variety of chromatin-modifying enzymes. Specifically, the histone lysine methyltransferase KMT2D is among the most frequently mutated genes in oral squamous cell carcinoma (OSCC). However, the mechanisms by which KMT2D affects the development of OSCC remain unclear.

Results

In the present study, we found that the expression of KMT2D was elevated in OSCC compared to paracancerous specimens and was correlated with a more advanced tumor grade. More importantly, knockdown of KMT2D impaired their reconstitution in patient-derived organoids and decreased the expression of CD133 and β-catenin in OSCC cells. In in vitro and in vivo models, knockdown of KMT2D reduced the colony formation, migration and invasion abilities of OSCC cells and delayed tumor growth. Mechanistically, the dual-luciferase reporter and co-immunoprecipitation assays in two individual OSCC cell lines indicated that KMT2D may cooperate with MEF2A to promote the transcription activity of CTNNB1, thereby enhancing WNT signaling.

Conclusion

The upregulation of KMT2D contributes to stem-like properties in OSCC cells by sustaining the MEF2A-mediated transcriptional activity of CTNNB1.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00785-8.

Regulatory RNAs, microRNA, long-non coding RNA and circular RNA roles in colorectal cancer stem cells

The properties of cancer stem cells (CSCs), such as self-renewal, drug resistance, and metastasis, have been indicated to be responsible for the poor prognosis of patients with colon cancers. The epigenetic regulatory network plays a crucial role in CSC properties. Regulatory non-coding RNA (ncRNA), including microRNAs, long noncoding RNAs, and circular RNAs, have an important influence on cell physiopathology. They modulate cells by regulating gene expression in different ways. This review discusses the basic characteristics and the physiological functions of colorectal cancer (CRC) stem cells. Elucidation of these ncRNAs will help us understand the pathological mechanism of CRC progression, and they could become a new target for cancer treatment.

N6-methyladenosine modification of CENPK mRNA by ZC3H13 promotes cervical cancer stemness and chemoresistance

BACKGROUND

Stemness and chemoresistance contribute to cervical cancer recurrence and metastasis. In the current study, we determined the relevant players and role of N⁶-methyladenine (m⁶A) RNA methylation in cervical cancer progression.

METHODS

The roles of m⁶A RNA methylation and centromere protein K (CENPK) in cervical cancer were analyzed using bioinformatics analysis. Methylated RNA immunoprecipitation was adopted to detect m⁶A modification of CENPK mRNA. Human cervical cancer clinical samples, cell lines, and xenografts were used for analyzing gene expression and function. Immunofluorescence staining and the tumorsphere formation, clonogenic, MTT, and EdU assays were performed to determine cell stemness, chemoresistance, migration, invasion, and proliferation in HeLa and SiHa cells, respectively. Western blot analysis, co-immunoprecipitation, chromatin immunoprecipitation, and luciferase reporter, cycloheximide chase, and cell fractionation assays were performed to elucidate the underlying mechanism.

RESULTS

Bioinformatics analysis of public cancer datasets revealed firm links between m⁶A modification patterns and cervical cancer prognosis, especially through ZC3H13-mediated m⁶A modification of CENPK mRNA. CENPK expression was elevated in cervical cancer, associated with cancer recurrence, and independently predicts poor patient prognosis [hazard ratio = 1.413, 95% confidence interval = 1.078 - 1.853, P = 0.012]. Silencing of CENPK prolonged the overall survival time of cervical cancer-bearing mice and improved the response of cervical cancer tumors to chemotherapy in vivo (P < 0.001). We also showed that CENPK was directly bound to SOX6 and disrupted the interactions of CENPK with β-catenin, which promoted β-catenin expression and nuclear translocation, facilitated p53 ubiquitination, and led to activation of Wnt/β-catenin signaling, but suppression of the p53 pathway. This dysregulation ultimately enhanced the tumorigenic pathways required for cell stemness, DNA damage repair pathways necessary for cisplatin/carboplatin resistance, epithelial-mesenchymal transition involved in metastasis, and DNA replication that drove tumor cell proliferation.

CONCLUSIONS

CENPK was shown to have an oncogenic role in cervical cancer and can thus serve as a prognostic indicator and novel target for cervical cancer treatment.

A chemical probe inhibitor targeting STAT1 restricts cancer stem cell traits and angiogenesis in colorectal cancer

Background

Colorectal cancer (CRC) is a worldwide cancer with rising annual incidence. New medications for patients with CRC are still needed. Recently, fluorescent chemical probes have been developed for cancer imaging and therapy. Signal transducer and activator of transcription 1 (STAT1) has complex functions in tumorigenesis and its role in CRC still needs further investigation.

Methods

RNA sequencing datasets in the NCBI GEO repository were analyzed to investigate the expression of STAT1 in patients with CRC. Xenograft mouse models, tail vein injection mouse models, and azoxymethane/dextran sodium sulfate (AOM/DSS) mouse models were generated to study the roles of STAT1 in CRC. A ligand-based high-throughput virtual screening approach combined with SWEETLEAD chemical database analysis was used to discover new STAT1 inhibitors. A newly designed and synthesized fluorescently labeled 4’,5,7-trihydroxyisoflavone (THIF) probe (BODIPY-THIF) elucidated the mechanistic actions of STAT1 and THIF in vitro and in vivo. Colonosphere formation assay and chick chorioallantoic membrane assay were used to evaluate stemness and angiogenesis, respectively.

Results

Upregulation of STAT1 was observed in patients with CRC and in mouse models of AOM/DSS-induced CRC and metastatic CRC. Knockout of STAT1 in CRC cells reduced tumor growth in vivo. We then combined a high-throughput virtual screening approach and analysis of the SWEETLEAD chemical database and found that THIF, a flavonoid abundant in soybeans, was a novel STAT1 inhibitor. THIF inhibited STAT1 phosphorylation and might bind to the STAT1 SH2 domain, leading to blockade of STAT1-STAT1 dimerization. The results of in vitro and in vivo binding studies of THIF and STAT1 were validated. The pharmacological treatment with BODIPY-THIF or ablation of STAT1 via a CRISPR/Cas9-based strategy abolished stemness and angiogenesis in CRC. Oral administration of BODIPY-THIF attenuated colitis symptoms and tumor growth in the mouse model of AOM/DSS-induced CRC.

Conclusions

This study demonstrates that STAT1 plays an oncogenic role in CRC. BODIPY-THIF is a new chemical probe inhibitor of STAT1 that reduces stemness and angiogenesis in CRC. BODIPY-THIF can be a potential tool for CRC therapy as well as cancer cell imaging.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-022-00803-4.

StemSC: a cross-dataset human stemness index for single-cell samples

Background

Stemness is defined as the potential of cells for self-renewal and differentiation. Many transcriptome-based methods for stemness evaluation have been proposed. However, all these methods showed low negative correlations with differentiation time and can’t leverage the existing experimentally validated stem cells to recognize the stem-like cells.

Methods

Here, we constructed a stemness index for single-cell samples (StemSC) based on relative expression orderings (REO) of gene pairs. Firstly, we identified the stemness-related genes by selecting the genes significantly related to differentiation time. Then, we used 13 RNA-seq datasets from both the bulk and single-cell embryonic stem cell (ESC) samples to construct the reference REOs. Finally, the StemSC value of a given sample was calculated as the percentage of gene pairs with the same REOs as the ESC samples.

Results

We validated the StemSC by its higher negative correlations with differentiation time in eight normal datasets and its higher positive correlations with tumor dedifferentiation in three colorectal cancer datasets and four glioma datasets. Besides, the robust of StemSC to batch effect enabled us to leverage the existing experimentally validated cancer stem cells to recognize the stem-like cells in other independent tumor datasets. And the recognized stem-like tumor cells had fewer interactions with anti-tumor immune cells. Further survival analysis showed the immunotherapy-treated patients with high stemness had worse survival than those with low stemness.

Conclusions

StemSC is a better stemness index to calculate the stemness across datasets, which can help researchers explore the effect of stemness on other biological processes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02803-5.

Mesenchymal stem cell-encapsulated cellulose nanofiber microbeads and enhanced biological activities by hyaluronic acid incorporation

Cell microencapsulation is a process to entrap viable and functional cells within a biocompatible and semi-permeable matrix to provide a favorable microenvironment to the cells. Cellulose nanofiber (CNF), a low-cost and sustainable cellulose-derived natural polymer, has been studied as a matrix for 3D stem cell culture in the form of a bulk hydrogel. Here, the preparation of CNF microbeads for the long-term 3D culture of human adipose-derived stem cells (hADSCs) was demonstrated. Furthermore, hyaluronic acid (HA) was physically incorporated into the stem cell encapsulated CNF microbeads with various molecular weights and concentrations to investigate its potential in enhancing the cellular bioactivities. The beneficial effects of HA incorporation on encapsulated cells were significant compared to CNF microbeads, especially with 700 kDa molecular weight and 0.2% in concentration in terms of cell proliferation (~2 times) and VEGF secretion (~2 times) while maintaining their stemness. All the results demonstrated that the HA-incorporated CNF microbeads could serve as a promising microencapsulation matrix for hADSCs.

Chemokines in Triple-Negative Breast Cancer Heterogeneity: New Challenges for Clinical Implications

Tumor heterogeneity is a hallmark of cancer and one of the primary causes of resistance to therapies. Triple-negative breast cancer (TNBC), which accounts for 15% to 20% of all breast cancers and is the most aggressive subtype, is very diverse, connected to metastatic potential and response to therapy. It is a very diverse disease at the molecular, pathologic, and clinical levels. TNBC is substantially more likely to recur and has a worse overall survival rate following diagnosis than other breast cancer subtypes. Chemokines, low molecular weight proteins that stimulate chemotaxis, have been shown to control the cues responsible for TNBC heterogeneity. In this review, we have focused on tumor heterogeneity and the role of chemokines in modulating tumor heterogeneity, since this is the most critical issue in treating TNBC. Additionally, we examined numerous cues mediated by chemokine networks that contribute to the heterogeneity of TNBC. Recent developments in our knowledge of the chemokine networks that regulate TNBC heterogeneity may pave the door for developing difficult-to-treat TNBC treatment options.

AMP- activated protein kinase (AMPK) promotes breast cancer stemness and drug resistance

Breast cancer stem cells (BCSCs) are a major cause of therapy resistance and tumour progression. Currently, their regulation is not entirely understood. Previous work from our laboratory demonstrated a context-specific pro-tumorigenic role for AMP-activated protein kinase (AMPK) under anchorage-deprivation and mammosphere formation, which are hallmarks of BCSCs. Therefore, we investigated the role of AMPK in the maintenance of BCSC state/function. AMPK depletion reduces serial sphere formation in vitro and tumour initiation in vivo. Intriguingly, tumour-derived cell analysis using stem cell markers and functional assays revealed that AMPK is required for the maintenance of BCSC populations in vivo. AMPK promotes the expression of stemness genes such as NANOG, SOX2 and BMI1 through the transcriptional upregulation of TWIST via promoter acetylation. Further, AMPK-driven stemness plays a critical role in doxorubicin resistance. Significantly, AMPK activity increased after chemotherapy in patient-derived tumour samples alongside an increase in stemness markers. Importantly, AMPK depletion sensitises mouse tumours to doxorubicin treatment. Our work indicates that targeting of AMPK in conjunction with regular chemotherapy is likely to reduce the stem cell pool and improve chemosensitivity in breast cancers.

Summary: AMPK inhibition in conjunction with regular chemotherapy is likely to reduce the stem cell pool and improve chemosensitivity and therapeutic outcomes in breast cancers.

Multiple roles of mothers against decapentaplegic homolog 4 in tumorigenesis, stem cells, drug resistance, and cancer therapy

The transforming growth factor (TGF)-β signaling pathway controls many cellular processes, including proliferation, differentiation, and apoptosis. Abnormalities in the TGF-β signaling pathway and its components are closely related to the occurrence of many human diseases, including cancer. Mothers against decapentaplegic homolog 4 (Smad4), also known as deleted in pancreatic cancer locus 4, is a typical tumor suppressor candidate gene locating at q21.1 of human chromosome 18 and the common mediator of the TGF-β/Smad and bone morphogenetic protein/Smad signaling pathways. It is believed that Smad4 inactivation correlates with the development of tumors and stem cell fate decisions. Smad4 also interacts with cytokines, miRNAs, and other signaling pathways, jointly regulating cell behavior. However, the regulatory function of Smad4 in tumorigenesis, stem cells, and drug resistance is currently controversial. In addition, Smad4 represents an attractive therapeutic target for cancer. Elucidating the specific role of Smad4 is important for understanding the mechanism of tumorigenesis and cancer treatment. Here, we review the identification and characterization of Smad4, the canonical TGF-β/Smad pathway, as well as the multiple roles of Smad4 in tumorigenesis, stem cells, and drug resistance. Furthermore, we provide novel insights into the prospects of Smad4-targeted cancer therapy and the challenges that it will face in the future.

FOXM1 mediates GDF-15 dependent stemness and intrinsic drug resistance in breast cancer

BACKGROUND

Stemness, a key component of breast cancer (BC) heterogeneity, is responsible for chemoresistance. Growth differentiation factor-15 (GDF-15) induces drug resistance and stemness in BC cells. In this study, the expressions and interactions of GDF-15, FOXM1, and stemness (OCT4 and SOX2), and drug resistance (ABCC5) markers were evaluated in BC.

METHODS AND RESULTS

40 diagnosed BC patients and 40 healthy controls were included in this study. Serum GDF-15 was significantly raised (p < 0.001) in BC patients. Expressions of GDF-15, OCT4, SOX2, and FOXM1 in BC tissue and cell lines (MCF-7 and MDA-MB-231) were determined by RT-PCR, while phosphorylated AKT (p-AKT) was analyzed by Western blot. Not only were the fold change expressions higher in cancer tissue as compared to surrounding control tissue, but a higher expression was observed for all the genes along with p-AKT in MDA-MB-231 cells compared to MCF-7. Tissue GDF-15 was significantly associated with ABCC5 (p < 0.001), OCT4 (p = 0.002), SOX2 (p < 0.001), and FOXM1 (p < 0.001). To further analyze the signaling pathway involved in stemness and drug resistance in BC, GDF-15 knockdown was performed, which reduced the expression of p-AKT, FOXM1, OCT4 and SOX2, and ABCC5, whereas recombinant GDF-15 treatment reversed the same. In silico analyses in UALCAN revealed a similar picture for these genes to that of BC tissue expression.

CONCLUSIONS

GDF-15 promotes stemness and intrinsic drug resistance in BC, possibly mediated by the p-AKT/FOXM1 axis.

Tanshinone IIA attenuates the stemness of breast cancer cells via targeting the miR-125b/STARD13 axis

BACKGROUND

Tanshinone II A is an effective component extracted from Salvia miltiorrhiza and the roles of Tanshinone IIA in regulating the stemness of tumor cells remain unclear. This work aims to explore the roles and underlying mechanisms of Tanshinone IIA in breast cancer stemness.

METHODS

In vitro mammary spheroid formation, flow cytometry assay on CD24^-/CD44⁺ sub-population, ALDH activity detection, cell viability assay and western blot analysis, and in vivo tumor-initiating analysis were performed to examine the effects of Tanshinone IIA on the stemness of breast cancer cells. MiRNAs-based transcriptome sequencing and data analysis, online dataset analysis, luciferase reporter assay combined with rescuing experiments were constructed to explore the underlying mechanisms.

RESULTS

Tanshinone IIA attenuated the stemness of breast cancer cells, evident by downregulating the expression of stemness markers, hindering the capacity of spheroid formation, decreasing the CD24^-/CD44⁺ sub-population in a concentration-dependent manner and reducing the tumor-initiating ability of breast cancer cells. Additionally, Tanshinone IIA enhanced adriamycin sensitivity and attenuated adriamycin resistance of breast cancer cells. Combined with miRNAs-based transcriptome sequencing assay, it was found that Tanshinone IIA downregulated miR-125b level and upregulated its target gene STARD13 (StAR-related lipid transfer protein 13) level, thus inactivating the miR-125b/STARD13 axis, which had been previously confirmed to promote breast cancer progression. Notably, miR-125b overexpression enhanced the stemness of breast cancer cells, and miR-125b overexpression or STARD13 knockdown impaired the inhibitory effects of Tanshinone IIA on the stemness of breast cancer cells.

CONCLUSIONS

Tanshinone IIA could attenuate the stemness of breast cancer cells via targeting the miR-125b/STARD13 axis.

Effects of carrier solutions on the viability and efficacy of canine adipose-derived mesenchymal stem cells

Background

Mesenchymal stem cells (MSCs) have favorable characteristics that render them a potent therapeutic tool. We tested the characteristics of MSCs after temporal storage in various carrier solutions, such as 0.9% saline (saline), 5% dextrose solution (DS), heparin in saline, and Hartmann’s solution, all of which are approved by the U.S. Food and Drug Administration (FDA). Phosphate-buffered saline, which does not have FDA approval, was also used as a carrier solution. We aimed to examine the effects of these solutions on the viability and characteristics of MSCs to evaluate their suitability and efficacy for the storage of canine adipose-derived MSCs (cADMSCs).

Results

We stored the cADMSCs in the test carrier solutions in a time-dependent manner (1, 6, and 12 h) at 4 °C, and analyzed cell confluency, viability, proliferation, self-renewability, and chondrogenic differentiation. Cell confluency was significantly higher in 5% DS and lower in phosphate-buffered saline at 12 h compared to other solutions. cADMSCs stored in saline for 12 h showed the highest viability rate. However, at 12 h, the proliferation rate of cADMSCs was significantly higher after storage in 5% DS and significantly lower after storage in saline, compared to the other solutions. cADMSCs stored in heparin in saline showed superior chondrogenic capacities at 12 h compared to other carrier solutions. The expression levels of the stemness markers, Nanog and Sox2, as well as those of the MSC surface markers, CD90 and CD105, were also affected over time.

Conclusion

Our results suggest that MSCs should be stored in saline, 5% DS, heparin in saline, or Hartmann’s solution at 4 °C, all of which have FDA approval (preferable storage conditions: less than 6 h and no longer than 12 h), rather than storing them in phosphate-buffered saline to ensure high viability and efficacy.

Interconnected high-dimensional landscapes of epithelial-mesenchymal plasticity and stemness in cancer

Establishing macrometastases at distant organs is a highly challenging process for cancer cells, with extremely high attrition rates. A very small percentage of disseminated cells have the ability to dynamically adapt to their changing micro-environments through reversibly switching to another phenotype, aiding metastasis. Such plasticity can be exhibited along one or more axes-epithelial-mesenchymal plasticity (EMP) and cancer stem cells (CSCs) being the two most studied, and often tacitly assumed to be synonymous. Here, we review the emerging concepts related to EMP and CSCs across multiple cancers. Both processes are multi-dimensional in nature; for instance, EMP can be defined on morphological, molecular and functional changes, which may or may not be synchronized. Similarly, self-renewal, multi-lineage potential, and resistance to anoikis and/or therapy may not all occur simultaneously in CSCs. Thus, understanding the complexity in defining EMP and CSCs is essential if we are to understand their contribution to cancer metastasis. This will require a more comprehensive understanding of the non-linearity of these processes. These processes are dynamic, reversible, and semi-independent in nature; cells traverse the inter-connected high-dimensional EMP and CSC landscapes in diverse paths, each of which may exhibit a distinct EMP-CSC coupling. Our proposed model offers a potential unifying framework for elucidating the coupled decision-making along these dimensions and highlights a key set of open questions to be answered.

CD44-positive cancer stem cells from oral squamous cell carcinoma exhibit reduced proliferation and stemness gene expression upon adipogenic induction

We proposed to assess adipogenic differentiation and its effect on the proliferation and stemness markers in CD44 + OSCC CSCs. D44 + CSCs were sorted by magnetic sorting from the single-cell suspension of the OSCC tumor. Adipogenic differentiation was induced by an adipogenic induction medium. Lipid droplet formation was confirmed by oil red O staining. The expression of the cell surface marker was analyzed by flow cytometry. Real-time qPCR was performed to examine the gene expression activity. CD44 + OSCC CSCs can differentiate into adipocytes and adipogenesis in these cells decrease their proliferation and stemness gene expression. Adipogenic induction can make the cancer stem cells from OSCC tumors lose their stemness potential. Oral cancer, especially OSCC, is a huge burden worldwide. Similar to other stem cells, cancer stem cells can differentiate into other lineage cells. Our study shows that the proliferation and stemness gene expression in the CSCs from OSCC tumors can be thwarted by inducing them to differentiate into adipocytes, which could be advantageous to find out new clinical approaches in the treatment of cancers, like OSCC.

Inactivation of PI3K/Akt promotes the odontoblastic differentiation and suppresses the stemness with autophagic flux in dental pulp cells

Background/purpose

Autophagy is involved in controlling differentiation of various cell types. The present study aimed to investigate the mechanism related to autophagy in regulating odontogenic differentiation of dental pulp cells.

Materials and methods

Human dental pulp cells (HDPCs) were cultured in differentiation inductive medium (DM) and odontoblastic differentiation and mineralization were evaluated by alkaline phosphatase (ALP) staining and Alizarin red S staining, respectively. Tooth cavity preparation was made on the mesial surface of lower first molars in rat. The expression of autophagy-related signal molecules was detected using Western blot analysis and Immunohistochemistry.

Results

HDPCs cultured in DM showed increased autophagic flux and declined phosphorylation of phosphoinositide 3-kinases (PI3K), protein kinase B (Akt), and mTOR. Dentin matrix protein-1 (DMP-1) and dentin sialoprotein (DSP), markers of odontoblastic differentiation, were upregulated and autophagic activation showing increased LC3-II and decreased p62 levels was observed during odontogenic differentiation of HDPCs. However, PI3K blocker 3-methyladenine (3MA), lentiviral shLC3 and Akt activator SC79 attenuated the expression of LC3II as well as DMP-1, ALP activity and mineralization enhanced in HDPCs under DM condition. In addition, 3MA, shLC3 and SC79 recovered the expression of pluripotency factor CD146, Oct4 and Nanog downregulated in DM condition. In rat tooth cavity preparation model, the expression of LC3B and DMP-1 was elevated near odontoblast-dentin layer during reparative dentin formation, whereas 3MA significantly reduced the expression of LC3B and DMP-1.

Conclusion

These findings indicated autophagy promotes the odontogenic differentiation of dental pulp cells modulating stemness via PI3K/Akt inactivation and the repair of pulp.

In Vitro Quantification of Cancer Stem Cells Using a Mammosphere Formation Assay

Cancer stem cells (CSCs) are a small subpopulation of self-renewing cancer cells that are present within tumors. In this chapter, we provide a detailed method for the quantification of CSCs in vitro through mammosphere formation.

Integrated genomic analysis of proteasome alterations across 11,057 patients with 33 cancer types: clinically relevant outcomes in framework of 3P medicine

Relevance

Proteasome, a cylindrical complex containing 19S regulatory particle lid, 19S regulatory particle base, and 20S core particle, acted as a major mechanism to regulate the levels of intracellular proteins and degrade misfolded proteins, which involved in many cellular processes, and played important roles in cancer biological processes. Elucidation of proteasome alterations across multiple cancer types will directly contribute to cancer medical services in the context of predictive, preventive, and personalized medicine (PPPM / 3P medicine).

Purpose

This study aimed to investigate proteasome gene alterations across 33 cancer types for discovery of effective biomarkers and therapeutic targets in the framework of PPPM practice in cancers.

Methods

Proteasome gene data, including gene expression RNAseq, somatic mutation, tumor mutation burden (TMB), copy number variant (CNV), microsatellite instability (MSI) score, clinical characteristics, immune phenotype, 22 immune cells, cancer stemness index, drug sensitivity, and related pathways, were systematically analyzed with publically available database and bioinformatics across 11,057 patients with 33 cancer types.

Results

Differentially expressed proteasome genes were extensively found between tumor and control tissues. PSMB4 occurred the top mutation event among proteasome genes, and those proteasome genes were significantly associated with TMB and MSI score. Most of proteasome genes were positively related to CNV among single deletion, control copy number, and single gain. Kaplan-Meier curves and COX regression survival analysis showed proteasome genes were significantly associated with patient survival rate across 33 cancer types. Furthermore, the expressions of proteasome genes were significantly different among different clinical stages and immune subtypes. The expressions of proteasome genes were correlated with immune-related scores (ImmuneScore, StromalScore, and ESTIMATEScore), 22 immune cells, and cancer stemness. The sensitivities of multiple drugs were closely related to proteasome gene expressions. The identified proteasome and proteasome-interacted proteins were significantly enriched in various cancer-related pathways.

Conclusions

This study provided the first landscape of proteasome alterations across 11,057 patients with 33 cancer types and revealed that proteasome played a significant and wide functional role in cancer biological processes. These findings are the precious scientific data to reveal the common and specific alterations of proteasome genes among 33 cancer types, which benefits the research and practice of PPPM in cancers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-021-00256-z.

Suppression of stemness and enhancement of chemosensibility in the resistant melanoma were induced by Astragalus polysaccharide through PD-L1 downregulation

Chemotherapy is commonly used in the clinical treatment of melanoma, but it is prone to resistance leading to the poor effectiveness. The mechanisms of resistance are complicated including the cancer stemness. Astragalus polysaccharide (APS) is one of the active components of traditional Chinese herbal medicine Astragalus Membranaceus. Our previous work was reported that APS had an inhibitory effect on the stemness of melanoma. In this study we established chemo-resistant melanoma cells and found that expression of stemness genes were upregulated in the resistant melanoma cells. And APS could downregulate expression of stemness genes. Furthermore, APS combined with cisplatin (DDP) could significantly slow down the tumor growth in the mouse model induced by DDP-resistant cells. In addition, we found that programmed death-ligand 1 (PD-L1) expression could be downregulated and the PI3K/AKT signaling could be affected by APS. These results suggested that APS could be a potential candidate in combination with chemotherapeutic agents, which might play a role in reducing the occurrence of resistance and improving the prognosis of melanoma patients.

REC8 enhances stemness and promotes metastasis of colorectal cancer through BTK/Akt/β-catenin signaling pathway

Cancer/testis antigens (CTAs) are often aberrantly expressed in cancer stem cells (CSCs) which are responsible for tumor metastasis. Rec8 meiotic recombination protein (REC8), a member of CTAs, shares distinct roles in various cancers, while its contribution to CSCs and colorectal cancer (CRC) remains unclear. We found that overexpression of REC8 facilitated the migration and invasion of CRC cells (DLD-1 and SW480 cells) in vitro and promoted the liver metastasis of CRC in vivo. Moreover, REC8 is highly expressed in CRC stem-like cells and is required for the maintenance of CSC stemness. Mechanistic studies suggested that REC8 mediated through the activation of Bruton tyrosine kinase (BTK). Inhibition of BTK by ibrutinib not only suppressed the migration and invasion-promoting ability, but also declined the increased expression of p-BTK, p-Akt, β-catenin, and CSC markers upon REC8 overexpression. Importantly, high expression of REC8 in cancerous tissues was related to advanced clinical stage and lymph node metastasis of 62 CRC patients, and REC8 was enriched in the cancerous cells positive for CSC markers. Collectively, our results indicate that REC8 promotes CRC metastasis by increasing cell stemness through BTK/Akt/β-catenin pathway.

SOX2 maintains the stemness of retinoblastoma stem-like cells through Hippo/YAP signaling pathway

PURPOSE

To explore the mechanisms underlying stemness maintenance of retinoblastoma (RB) stem cells (RSCs).

METHODS

The retinoblastoma stem-like cells (RSLCs) were isolated by single cell cloning in combination of examination of sphere-forming capacities. The stemness of the cells were characterized by the sphere-forming capacity and the expression levels of RSCs markers. Gene manipulation was performed by lentivirus system. Transcriptional regulation was identified by qRT-PCR, luciferase reporter, nuclear run-on and DNA pull-down assay. Spearman analysis was employed for correlation analysis of genes in tumor tissues of RB patients.

RESULTS

The isolated RSLCs exhibited enhanced sphere-forming capacity and constantly higher levels of CD44, ABCG2, SOX2 and PAX6, but not CD133. SOX2 positively regulated the stemness of RSLCs. SOX2 directly binds to the promoters of WWTR1 and YAP and transcriptionally activates WWTR1 and YAP. Knockdown of WWTR1 or YAP partially abolished the effect of SOX2 on the stemness of RSLCs.

CONCLUSIONS

SOX2, as a key deriver, maintains RB stemness by activating Hippo/YAP signaling. Inhibition of Hippo/YAP signaling would be an effective strategy for human RB caused by SOX2 upregulation.

Manuka honey in combination with 5-Fluorouracil decreases physical parameters of colonspheres enriched with cancer stem-like cells and reduces their resistance to apoptosis

The aim of the present work was to evaluate the in vitro effect of Manuka honey and its combination with 5-Fu, the most common drug used in the treatment of colon cancer, on the morphological and physical parameters of colonspheres enriched with cancer stem-like cells deriving from HCT-116 colon adenocarcinoma cell line and on the apoptosis rate. Manuka honey, alone and more in combination with 5-Fu, reduced the weight, the diameter and mass density of the spheroids and induced apoptosis through the downregulation of many apoptosis inhibitors, including IAPs (Livin, Survivin, XIAP), IGFs (IGF-I, IGF-II and IGF-IR) and HSPs (HSP-27, HSP-60 and HSP-70). These results led to a reduction in the survival ability of cancer stem-like cells, as well as to a chemosensitizing effect of honey towards 5-Fu, considering that apoptosis resistance is one of the main causes of cancer stem-like cells chemoresistance.

CPT2 downregulation triggers stemness and oxaliplatin resistance in colorectal cancer via activating the ROS/Wnt/β-catenin-induced glycolytic metabolism

Carnitine palmitoyltransferase 2 (CPT2) has been demonstrated to act as a tumor promotor or suppressor in different types of cancers. However, little is known about the effect of CPT2 on colorectal cancer (CRC). In the present study, we analyzed CPT2 expression in CRC tissues and cells. CPT2 was overexpressed in CRC cell lines (SW480 and RKO), and its effects and molecular mechanism on the proliferation, glycolysis, stemness, and oxaliplatin sensitivity were investigated. The xenograft experiment was used to confirm the influence of CPT2 on CRC tumorigenesis in vivo. We found that CPT2 expression was significantly downregulated in CRC patients, and its lower expression was associated with the poor prognosis, large tumor size, advanced TNM stage, and poor histological grade differentiation of patients. Upregulation of CPT2 significantly inhibited the proliferation, glycolytic metabolism, cancer stem cell properties, and oxaliplatin resistance in CRC cells. Also, the increase of CPT2 inhibited tumorigenesis, stemness and glycolysis, while enhanced oxaliplatin sensitivity in mouse models. Mechanistically, CPT2 functioned via suppressing the activation of Wnt/β-catenin pathway through repressing ROS production. In conclusion, our results demonstrated that CPT2 was decreased in CRC, and CPT2 downregulation could trigger stemness and oxaliplatin resistance in CRC via activating the ROS/Wnt/β-catenin-induced glycolytic metabolism. This study indicates that CPT2 is a potential therapeutic target for CRC.

Identification and characterization of pulmonary mesenchymal stem cells derived from rat fetal lung tissue

Pulmonary mesenchymal stem cells (PMSCs) have great potential in lung tissue repair and regeneration, which have been isolated from some mammalian species, including mice, bovine and pig. However, the isolation, characteristics and differentiation potential of rat PMSCs have not been reported. In this study, we successfully isolated PMSCs from Sprague-Dawley rat fetal lung tissue in vitro for the first time and attempted to evaluate its multilineage differentiation potentials. The cultured PMSCs showed typical spindle-shaped morphology and high proliferative potential, and could be passaged for at least 13 passages and maintained high hereditary stability with more than 93.6 % of cells were diploid (2n = 42) by G-banding analysis. Furthermore, the PMSCs could express mesenchymal markers Sca-1, CD29, CD44, CD73 and CD90, but not hematopoietic markers CD34 and CD45. Besides, the expression of cell markers of AT2 (SFTPC), AT1 (PDPN) and macrophage (CD11b) were also negative. Cell cycle examination revealed majority of the PMSCs were in G0/G1 phase, which are similar with previously reported pig PMSCs. In addition, the PMSCs were multipotent and could differentiated into osteocytes, adipocytes, hepatocytes and neurons in vitro. Together, the present study demonstrated the stemness and multi-differentiation potentials of rat PMSCs, which conferred a potential regenerative cell resource for cell regenerative therapy of lung injury.

VEGFa/VEGFR2 autocrine and paracrine signaling promotes cervical carcinogenesis via β-catenin and snail

VEGF secretion into the tumor microenvironment by cancer cells regulates several oncogenic signaling pathways and cancer-regulated angiogenesis. VEGFR receptors are exclusively present on endothelial cells to maintain their biological homeostasis. The acquisition of unique VEGFR2 receptor and VEGFa in cervical cancer (CC) cells reflects VEGFa/VEGFR2 autocrine machinery. Given the critical role of VEGFR2 in endothelial cell proliferation, migration, and angiogenesis, we explored its function in CC epithelial-mesenchymal transition (EMT) and stemness. Here we report that VEGFR2 regulates cancer-induced angiogenesis and EMT-linked stemness in CC cells via AKT/GSK3β/β-catenin and Snail pathway. Receptor tyrosine kinase inhibitor (RTKi) of VEGFR, Pazopanib (PAZ), shows potential anti-VEGFR2 activity and inhibits VEGFa induced metastatic events such as migration, invasion, and anoikis resistance in CC cells. Similarly, PAZ also attenuates cancer-regulated angiogenesis by inhibiting VE-cadherin internalization in endothelial cells followed by inhibition of endothelial cell migration. Selective depletion of VEGFR2 ligand VEGFa in CC cells also attenuates EMT, metastatic events, and inhibition of cancer-induced angiogenesis. In addition, blocking of VEGFR2 signaling in CC cells via PAZ or shRNA alters the formation of cervical tumorspheres (TS) and their successive generation. Collectively, inhibition of functional VEGFa/VEGFR2 autocrine and paracrine axis ceases the cancer-promoting events in cervical cancer cells. Based on the finding in this study, this oncogenic pathways could be used as a potential therapeutic target in a clinical setting with conventional radio-chemotherapy to achieve synergistic killing of CC cells.

Secretome of Stem Cells: Roles of Extracellular Vesicles in Diseases, Stemness, Differentiation, and Reprogramming

Increasing evidence suggests that stem cells or stem cell-derived cells may contribute to tissue repair, not only by replacing lost tissue but also by delivering complex sets of secretory molecules, called secretomes, into host injured tissues. In recent years, extracellular vesicles (EVs) have gained much attention for their diverse and important roles in a wide range of pathophysiological processes. EVs are released from most types of cells and mediates cell-cell communication by activating receptors on target cells or by being taken up by recipient cells. EVs, including microvesicles and exosomes, encapsulate and carry proteins, nucleic acids, and lipids in the lumen and on the cell surface. Thus, EV-mediated intercellular communication has been extensively studied across various biological processes. While a number of investigations has been conducted in different tissues and body fluids, the field lacks a systematic review on stem cell-derived EVs, especially regarding their roles in stemness and differentiation. Here, we provide an overview of the pathophysiological roles of EVs and summarize recent findings focusing on EVs released from various types of stem cells. We also highlight emerging evidence for the potential implication of EVs in self-renewal, differentiation, and reprograming and discuss the benefits and limitations in translational approaches.

[Expression of hepatocyte nuclear factor 4γ in gastric carcinoma and its role in cell proliferation and stemness]

Objective: To explore the role and molecular mechanism of hepatocyte nuclear factor 4γ (HNF4γ) in proliferation and stemness of gastric cancer. Methods: A total of 102 cases of paraffin-embedded gastric cancer tissues and matched adjacent gastric tissues and 42 cases of fresh-frozen tissues derived from gastric patients who received radical gastrectomy were collected from the First Affiliated Hospital of Zhengzhou University between 2012 to 2015. The expression of HNF4γ was tested by immunohistochemical staining, quantitative real-time polymerase chain reaction (qRT-PCR). HNF4γ overexpressed (AGS-HNF4γ) and shRNA silenced (HGC27-shHNF4γ) gastric cell lines were established. The effects of HNF4γ on cell proliferation and stemness were verified by XTT, clone formation and sphere formation assay. The expression of CD44 was detected by western blot. Results: The mRNA expression level of HNF4γ in fresh-frozen gastric cancer tissue was (12.43±2.702), which was significantly higher than (3.639±1.109) in normal tissue (P<0.001). The high protein expression rate of HNF4γ in paraffin-embedded gastric cancer tissues was 41.2% (42/102), which was significantly higher than 8.8% (9/102) in normal gastric mucosa tissue (P< 0.001). The protein expression of HNF4γ was closely related to the tumor differentiation, infiltration depth, lymph node metastasis and tumor stage (P<0.05). The median survival interval of patients with HNF4γ high expression was 25 months, the 3-year survival rate was 4.8% (2/42), significantly lower than 38 months and 51.7% (31/60) of patients with normal HNF4γ expression (P<0.001). The proliferation and CD44 protein expression of AGS-HNF4γ cells were significantly higher than those of the AGS-Vector cells. The number of clone formation, sphere formation rate of AGS-HNF4γ cells were 243.5±24.5 and (83.5±3.9)%, significantly higher than 81.0±16.0 and (21.8±5.6)% of AGS-Vector cells (P=0.030 and P=0.010, respectively). The proliferation and CD44 protein expression of HGC27-shHNF4 cells were significantly lower than those of the HGC27-vector cells. The number of clone formation, sphere formation rate of HGC27-shHNF4 cells were 26.0±1.0 and (20.8±8.4)%, significantly higher than 83.5±4.5 and (72.5±4.8)% of HGC27-vector cells (P=0.006 and P=0.030, respectively). Conclusions: HNF4γ is upregulated in the gastric cancer tissues and related with the poor prognosis of patients with gastric cancer. Overexpression of HNF4γ promotes the proliferation and remains the stemness of gastric cancer cells by upregulating the expression of CD44.

TMPRSS4 promotes cancer stem-like properties in prostate cancer cells through upregulation of SOX2 by SLUG and TWIST1

Background

Transmembrane serine protease 4 (TMPRSS4) is a cell surface–anchored serine protease. Elevated expression of TMPRSS4 correlates with poor prognosis in colorectal cancer, gastric cancer, prostate cancer, non–small cell lung cancer, and other cancers. Previously, we demonstrated that TMPRSS4 promotes invasion and proliferation of prostate cancer cells. Here, we investigated whether TMPRSS4 confers cancer stem–like properties to prostate cancer cells and characterized the underlying mechanisms.

Methods

Acquisition of cancer stem–like properties by TMPRSS4 was examined by monitoring anchorage-independent growth, tumorsphere formation, aldehyde dehydrogenase (ALDH) activation, and resistance to anoikis and drugs in vitro and in an early metastasis model in vivo. The underlying molecular mechanisms were evaluated, focusing on stemness-related factors regulated by epithelial–mesenchymal transition (EMT)-inducing transcription factors. Clinical expression and significance of TMPRSS4 and stemness-associated factors were explored by analyzing datasets from The Cancer Genome Atlas (TCGA).

Results

TMPRSS4 promoted anchorage-independent growth, ALDH activation, tumorsphere formation, and therapeutic resistance of prostate cancer cells. In addition, TMPRSS4 promoted resistance to anoikis, thereby increasing survival of circulating tumor cells and promoting early metastasis. These features were accompanied by upregulation of stemness-related factors such as SOX2, BMI1, and CD133. SLUG and TWIST1, master EMT-inducing transcription factors, made essential contributions to TMPRSS4-mediated cancer stem cell (CSC) features through upregulation of SOX2. SLUG stabilized SOX2 via preventing proteasomal degradation through its interaction with SOX2, while TWIST1 upregulated transcription of SOX2 by interacting with the proximal E-box element in the SOX2 promoter. Clinical data showed that TMPRSS4 expression correlated with the levels of SOX2, PROM1, SNAI2, and TWIST1. Expression of SOX2 was positively correlated with that of TWIST1, but not with other EMT-inducing transcription factors, in various cancer cell lines.

Conclusions

Together, these findings suggest that TMPRSS4 promotes CSC features in prostate cancer through upregulation of the SLUG- and TWIST1-induced stem cell factor SOX2 beyond EMT. Thus, TMPRSS4/SLUG–TWIST1/SOX2 axis may represent a novel mechanism involved in the control of tumor progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02147-7.

GLRX3, a novel cancer stem cell-related secretory biomarker of pancreatic ductal adenocarcinoma

Background

Cancer stem cells (CSCs) are implicated in carcinogenesis, cancer progression, and recurrence. Several biomarkers have been described for pancreatic ductal adenocarcinoma (PDAC) CSCs; however, their function and mechanism remain unclear.

Method

In this study, secretome analysis was performed in pancreatic CSC-enriched spheres and control adherent cells for biomarker discovery. Glutaredoxin3 (GLRX3), a novel candidate upregulated in spheres, was evaluated for its function and clinical implication.

Results

PDAC CSC populations, cell lines, patient tissues, and blood samples demonstrated GLRX3 overexpression. In contrast, GLRX3 silencing decreased the in vitro proliferation, migration, clonogenicity, and sphere formation of cells. GLRX3 knockdown also reduced tumor formation and growth in vivo. GLRX3 was found to regulate Met/PI3K/AKT signaling and stemness-related molecules. ELISA results indicated GLRX3 overexpression in the serum of patients with PDAC compared to that in healthy controls. The sensitivity and specificity of GLRX3 for PDAC diagnosis were 80.0 and 100%, respectively. When GLRX3 and CA19–9 were combined, sensitivity was significantly increased to 98.3% compared to that with GLRX3 or CA19–9 alone. High GLRX3 expression was also associated with poor disease-free survival in patients receiving curative surgery.

Conclusion

Overall, these results indicate GLRX3 as a novel diagnostic marker and therapeutic target for PDAC targeting CSCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08898-y.

The sulfiredoxin-peroxiredoxin redox system regulates the stemness and survival of colon cancer stem cells

Cancer stem cells (CSCs) initiate tumor formation and are known to be resistant to chemotherapy. A metabolic alteration in CSCs plays a critical role in stemness and survival. However, the association between mitochondrial energy metabolism and the redox system remains undefined in colon CSCs. In this study, we assessed the role of the Sulfiredoxin-Peroxiredoxin (Srx-Prx) redox system and mitochondrial oxidative phosphorylation (OXPHOS) in maintaining the stemness and survival of colon CSCs. Notably, Srx contributed to the stability of PrxI, PrxII, and PrxIII proteins in colon CSCs. Increased Srx expression promoted the stemness and survival of CSCs and was important for the maintenance of the mitochondrial OXPHOS system. Furthermore, Nrf2 and FoxM1 led to OXPHOS activation and upregulated expression of Srx-Prx redox system-related genes. Therefore, the Nrf2/FoxM1-induced Srx-Prx redox system is a potential therapeutic target for eliminating CSCs in colon cancer.

Circular RNA circPIP5K1A contributes to cancer stemness of osteosarcoma by miR-515-5p/YAP axis

Background

Osteosarcoma is a common type of bone tumors and frequently occurs in children and adolescents. Cancer stem cells (CSCs) are a unique sub-type of self-renewal cancer cells and the stemness of cancer cells are involved in the spread, recurrence, metastasis, and even therapeutic resistance. However, the regulation mechanisms of CSCs in osteosarcoma are poorly understood. Circular RNA (circRNA) is a unique sort of non-coding RNAs and widely participate in the modulation of cancer progression.

Methods

In this study, we identified the critical function of circular RNA circPIP5K1A in stemness of osteosarcoma cells.

Results

CircPIP5K1A expression was significantly enhanced in clinical osteosarcoma tissues compared with the adjacent normal tissues. The depletion of circPIP5K1A by siRNA repressed osteosarcoma cell viabilities and induced osteosarcoma cell apoptosis. The suppression of circPIP5K1A attenuated the capabilities of invasion and migration of osteosarcoma cells. The circPIP5K1A knockdown increased E-Cadherin expression and decreased Vimentin expression in osteosarcoma cells. The sphere formation abilities of osteosarcoma cells were repressed by the depletion of circPIP5K1A. The CD133⁺CD44⁺ cell population of osteosarcoma cells was reduced by circPIP5K1A knockdown. The expression of ALDH1 and Nanog was decreased by the inhibition of circPIP5K1A in osteosarcoma cells. Mechanically, circPIP5K1A enhanced YAP expression by targeting miR-515-5p. MiR-515-5p inhibited stemness of osteosarcoma cells. The CSCs properties of osteosarcoma cells were repressed by circPIP5K1A knockdown or miR-515-5p mimic, while miR-515-5p inhibitor or YAP overexpression reversed circPIP5K1A knockdown-induced repression. Tumor xenograft analysis in nude mice demonstrated that the depletion of circPIP5K1A represses osteosarcoma cell growth in vivo.

Conclusion

In conclusion, we identified that circular RNA circPIP5K1A contributed to cancer stemness of osteosarcoma by miR-515-5p/YAP axis. Targeting circPIP5K1A may be considered as a potential therapeutic strategy for osteosarcoma treatment.

Transitioning pre-clinical glioblastoma models to clinical settings with biomarkers identified in 3D cell-based models: A systematic scoping review

Glioblastoma (GBM) remains incurable despite the overwhelming discovery of 2-dimensional (2D) cell-based potential therapeutics since the majority of them have met unsatisfactory results in animal and clinical settings. Incremental empirical evidence has laid the widespread need of transitioning 2D to 3-dimensional (3D) cultures that better mimic GBM's complex and heterogenic nature to allow better translation of pre-clinical results. This systematic scoping review analyses the transcriptomic data involving 3D models of GBM against 2D models from 22 studies identified from four databases (PubMed, ScienceDirect, Medline, and Embase). From a total of 499 genes reported in these studies, 313 (63%) genes were upregulated across 3D models cultured using different scaffolds. Our analysis showed that 4 of the replicable upregulated genes are associated with GBM stemness, epithelial to mesenchymal transition (EMT), hypoxia, and migration-related genes regardless of the type of scaffolds, displaying close resemblances to primitive undifferentiated tumour phenotypes that are associated with decreased overall survival and increased hazard ratio in GBM patients. The upregulation of drug response and drug efflux genes (e.g. cytochrome P450s and ABC transporters) mirrors the GBM genetic landscape that contributes to in vivo and clinical treatment resistance. These upregulated genes displayed strong protein-protein interactions when analysed using an online bioinformatics software (STRING). These findings reinforce the need for widespread transition to 3D GBM models as a relatively inexpensive humanised pre-clinical tool with suitable genetic biomarkers to bridge clinical gaps in potential therapeutic evaluations.

DKK1 inhibits canonical Wnt signaling in human papillomavirus-positive penile cancer cells

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Elevated expression of Wnt pathway associated factors in HPV-positive penile cancer cells.

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lacking nuclear beta-catenin translocation indicated an actively abrogated Wnt signaling.

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elevated expression of the Wnt antagonist DKK1 in HPV-positive penile cancer cells.

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DKK1-driven autocrine Wnt pathway inhibition in penile cancer cells.

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DKK1⁺ penile cancers are with a higher frequency HPV⁺, less differentiated and grow more aggressively.

Penile squamous cell cancer (PSCC) is the most frequent penile malignant disease. Infections with human papillomaviruses (HPV) are a major etiologic driver of PSCC. However, the molecular details of the underlying carcinogenesis are understudied because of rare clinical specimens and missing cell lines. Here, we investigated if the expression of high-risk HPV16 oncogenes causes an augmentation of the Wnt pathway using unique HPV-positive penile cancer (PeCa) cell lines in monolayer and organotypic 3D raft cultures as well as tissue micro arrays containing clinical tissue specimens. The HPV oncoproteins enhanced the expression of Leucine-rich repeat-containing G-protein coupled receptor 6 (LGR6) and the HPV-positive PeCa cells expressed a signature of Wnt target and stemness-associated genes. However, the notable lack of nuclear β-catenin in vitro and in situ raised the question if the enhanced expression of Wnt pathway factors is tantamount to an active Wnt signaling. Subsequent TOP-flash reporter assays revealed Wnt signaling as absent and not inducible by respective Wnt ligands in PeCa cell lines. The HPV-positive PeCa cells and especially HPV-positive PeCa specimens of the tumor core expressed the Wnt antagonist and negative feedback-regulator Dickkopf1 (DKK1). Subsequent neutralization experiments using PeCa cell line-conditioned media demonstrated that DKK1 is capable to impair ligand-induced Wnt signaling. While gene expression analyses suggested an augmented and active canonical Wnt pathway, the respective signaling was inhibited due to the endogenous expression of the antagonist DKK1. Subsequent TMA stainings indicated Dkk1 as linked with HPV-positivity and metastatic disease progression in PeCa suggesting potential as a prognostic marker.

Integrins regulate stemness in solid tumor: an emerging therapeutic target

Integrins are the adhesion molecules and transmembrane receptors that consist of α and β subunits. After binding to extracellular matrix components, integrins trigger intracellular signaling and regulate a wide spectrum of cellular functions, including cell survival, proliferation, differentiation and migration. Since the pattern of integrins expression is a key determinant of cell behavior in response to microenvironmental cues, deregulation of integrins caused by various mechanisms has been causally linked to cancer development and progression in several solid tumor types. In this review, we discuss the integrin signalosome with a highlight of a few key pro-oncogenic pathways elicited by integrins, and uncover the mutational and transcriptomic landscape of integrin-encoding genes across human cancers. In addition, we focus on the integrin-mediated control of cancer stem cell and tumor stemness in general, such as tumor initiation, epithelial plasticity, organotropic metastasis and drug resistance. With insights into how integrins contribute to the stem-like functions, we now gain better understanding of the integrin signalosome, which will greatly assist novel therapeutic development and more precise clinical decisions.

SOX transcription factors and glioma stem cells: Choosing between stemness and differentiation

Glioblastoma (GBM) is the most common, most aggressive and deadliest brain tumor. Recently, remarkable progress has been made towards understanding the cellular and molecular biology of gliomas. GBM tumor initiation, progression and relapse as well as resistance to treatments are associated with glioma stem cells (GSCs). GSCs exhibit a high proliferation rate and self-renewal capacity and the ability to differentiate into diverse cell types, generating a range of distinct cell types within the tumor, leading to cellular heterogeneity. GBM tumors may contain different subsets of GSCs, and some of them may adopt a quiescent state that protects them against chemotherapy and radiotherapy. GSCs enriched in recurrent gliomas acquire more aggressive and therapy-resistant properties, making them more malignant, able to rapidly spread. The impact of SOX transcription factors (TFs) on brain tumors has been extensively studied in the last decade. Almost all SOX genes are expressed in GBM, and their expression levels are associated with patient prognosis and survival. Numerous SOX TFs are involved in the maintenance of the stemness of GSCs or play a role in the initiation of GSC differentiation. The fine-tuning of SOX gene expression levels controls the balance between cell stemness and differentiation. Therefore, innovative therapies targeting SOX TFs are emerging as promising tools for combatting GBM. Combatting GBM has been a demanding and challenging goal for decades. The current therapeutic strategies have not yet provided a cure for GBM and have only resulted in a slight improvement in patient survival. Novel approaches will require the fine adjustment of multimodal therapeutic strategies that simultaneously target numerous hallmarks of cancer cells to win the battle against GBM.

miR-3065-3p promotes stemness and metastasis by targeting CRLF1 in colorectal cancer

BACKGROUND

Colorectal cancer is one of the most common malignancy in the world. It has been reported that cancer stem cells (CSCs) serve as the primary drivers of tumorigenesis and tumor progression. There is an urgent need to explore novel molecules that regulate CSCs or their signatures. Increasing evidence has shown that miRNAs are involved in tumorigenesis and progression. Here, we aim to explore the regulatory effect and mechanism of miR-3065-3p on the stemness of colorectal cancer.

METHODS

The expression of miR-3065-3p in colorectal cancer and the association of miR-3065-3p expression with prognosis of patients with colorectal cancer were analyzed using TCGA dataset or clinical cases. Gain or loss of function in different models, including colorectal cancer cell lines and orthotopic xenograft or liver metastatic mouse model, were used to investigate the effects of miR-3065-3p on colorectal cancer stemness and metastasis in vitro and in vivo. Cancer stemness was analyzed by detecting the ability of migration and invasion, NANOG, OCT4, and SOX2 expression, ALDH activity and sphere formation. In addition, the interaction of miR-3065-3p and cytokine receptor-like factor 1 (CRLF1) was analyzed theoretically and identified by the luciferase reporter assay. Moreover, the correlation between CRLF1 expression and miR-3065-3p was analyzed in colorectal cancer tissues. Finally, the effect of CRLF1 on the stemness and metastasis of colorectal cancer in vitro and in vivo was assessed.

RESULTS

In this report, we found that miR-3065-3p was overexpressed in colorectal cancer and that its high expression was associated with poor prognosis of patients with colorectal cancer. miR-3065-3p promotes the stemness and metastasis of colorectal cancer. Furthermore, CRLF1 was the downstream target of miR-3065-3p and inhibited the stemness of colorectal cancer. In addition, CRLF1 expression was negatively correlated with miR-3065-3p in colorectal cancer tissues. And, CRLF1 mediated the effects of miR-3065-3p on promoting stemness of colorectal cancer cells.

CONCLUSION

Our data suggest that miR-3065-3p promoted the stemness and metastasis of colorectal cancer by targeting CRLF1. miR-3065-3p might serve as a promising prognostic marker as well as a therapeutic target for colorectal cancer.

AKT inhibitor AZD5363 suppresses stemness and promotes anti-cancer activity of 3,3'-diindolylmethane in human breast cancer cells

3,3'-diindolylmethane (DIM) is a dimer compound converted from Indoly-3-carbinol that had been studied as promising chemo-preventive agent against breast cancer. In this study, we observed that proportion of CD133⁺Nanog⁺ subpopulation in MCF-7 cells was significantly increased after DIM administration with up-regulated AKT activity by using CyTOF assay. SPADE analysis revealed this stem-like subpopulation exhibited apoptosis-resistance property against DIM treatment. By combining with AKT inhibitor AZD5363, DIM induced CD133 expression could be suppressed. In addition, a combination treatment of MCF-7 and MDA-MB-231 breast cancer cells with DIM and AZD5363 showed synergistic decreases in cell proliferation and induced apoptosis. Furthermore, results from imaging flow cytometry suggested that FoxO3a nuclear localization and PUMA expression could be improved by combination of AZD5363 with DIM. Taken together, the above observations suggested that the combination of AZD5363 with DIM could be developed as potential therapy for breast cancer.

Silencing PFKP restrains the stemness of hepatocellular carcinoma cells

BACKGROUND

Glycolysis reprogramming is deeply involved in the progression of hepatocellular carcinoma (HCC), in which HCC cells with stemness traits play important roles as well. Thus, whether platelet isoform of phosphofructokinase 1 (PFKP), a rate-limiting enzyme in glycolysis, contributes to the maintenance of stemness of HCC cells is worth investigation.

METHODS

PFKP levels were compared between human hepatocellular carcinoma and adjacent normal tissues by Western blotting and immunohistochemistry. The relationship between PFKP expression and clinic pathological features was also analyzed. Furthermore, the colony formation capabilities and the levels of stemness markers (ALDH1, CD44, CD133, Sox-2) as well as β-catenin were compared between HCC cells either undergoing PFKP silencing or overexpression.

RESULTS

PFKP levels were higher in HCC as compared to normal hepatic tissues. Silencing PFKP decreased HCC proliferation, colony formation capabilities, and levels of stemness markers and β-catenin; whereas overexpressing PFKP demonstrated the opposite effects.

CONCLUSION

PFKP promoted HCC proliferation and contributed to the maintenance of HCC stemness. Silencing PFKP could restrain the stemness of HCC, suggesting that PFKP may be a potential therapeutic target for HCC treatment.

Exosomes secreted by M2 macrophages promote cancer stemness of hepatocellular carcinoma via the miR-27a-3p/TXNIP pathways

OBJECTIVE

Accumulating evidence has suggested that microRNAs (miRNAs) derived from M2 macrophage-derived exosomes (M2 exosomes) can regulate the progression of hepatocellular carcinoma (HCC). Nevertheless, the effect of miR-27a-3p derived from M2 exosomes on HCC has not been reported. We aim to explore the role of M2 exosomal miR-27a-3p in the cancer stemness of HCC via regulating thioredoxin-interacting protein (TXNIP).

METHODS

Exosomes were extracted from transfected M2 macrophages and were then co-cultured with HCC cells. Expression of miR-27a-3p and TXNIP, stemness, proliferation, drug resistance, migration, invasion and in vivo tumorigenicity of HCC cells were determined to assess the role of M2 exosomal miR-27a-3p in HCC. The binding relationship between miR-27a-3p and TXNIP was detected.

RESULTS

MiR-27a-3p was upregulated and TXNIP was downregulated in HCC cells, and M2 exosomes further upregulated miR-27a-3p. The upregulated M2 exosomal miR-27a-3p promoted stemness, proliferation, drug resistance, migration, invasion and in vivo tumorigenicity of HCC cells. TXNIP was confirmed as a target gene of miR-27a-3p.

CONCLUSION

M2 macrophages-derived exosomal miR-27a-3p promotes cancer stemness of HCC via downregulating TXNIP.

Macrophages and cancer stem cells: a malevolent alliance

Myeloid cells infiltrating tumors are gaining ever growing attention in the last years because their pro-tumor and immunosuppressive functions are relevant for disease progression and therapeutic responses. The functional ambiguity of tumor-associated macrophages (TAMs), mostly promoting tumor evolution, is a challenging hurdle. This is even more evident in the case of cancer stem cells (CSCs); as active participants in the specialized environment of the cancer stem cell niche, TAMs initiate a reciprocal conversation with CSCs. TAMs contribute to protect CSCs from the hostile environment (exogenous insults, toxic compounds, attacks from the immune cells), and produce several biologically active mediators that modulate crucial developmental pathways that sustain cancer cell stemness. In this review, we have focused our attention on the interaction between TAMs and CSCs; we describe how TAMs impact on CSC biology and, in turn, how CSCs exploit the tissue trophic activity of macrophages to survive and progress. Since CSCs are responsible for therapy resistance and tumor recurrence, they are important therapeutic targets. In view of the recent success in oncology obtained by stimulating the immune system, we discuss some macrophage-targeted therapeutic strategies that may also affect the CSCs and interrupt their malevolent alliance.

Stem cells' centrosomes: How can organelles identified 130 years ago contribute to the future of regenerative medicine?

At the core of regenerative medicine lies the expectation of repair or replacement of damaged tissues or whole organs. Donor scarcity and transplant rejection are major obstacles, and exactly the obstacles that stem cell-based therapy promises to overcome. These therapies demand a comprehensive understanding of the asymmetric division of stem cells, i.e. their ability to produce cells with identical potency or differentiated cells. It is believed that with better understanding, researchers will be able to direct stem cell differentiation. Here, we describe extraordinary advances in manipulating stem cell fate that show that we need to focus on the centrosome and the centrosome-derived primary cilium. This belief comes from the fact that this organelle is the vehicle that coordinates the asymmetric division of stem cells. This is supported by studies that report the significant role of the centrosome/cilium in orchestrating signaling pathways that dictate stem cell fate. We anticipate that there is sufficient evidence to place this organelle at the center of efforts that will shape the future of regenerative medicine.

Lipid droplets as metabolic determinants for stemness and chemoresistance in cancer

Previously regarded as simple fat storage particles, new evidence suggests that lipid droplets (LDs) are dynamic and functional organelles involved in key cellular processes such as membrane biosynthesis, lipid metabolism, cell signalling and inflammation. Indeed, an increased LD content is one of the most apparent features resulting from lipid metabolism reprogramming necessary to support the basic functions of cancer cells. LDs have been associated to different cellular processes involved in cancer progression and aggressiveness, such as tumorigenicity, invasion and metastasis, as well as chemoresistance. Interestingly, all of these processes are controlled by a subpopulation of highly aggressive tumoral cells named cancer stem cells (CSCs), suggesting that LDs may be fundamental elements for stemness in cancer. Considering the key role of CSCs on chemoresistance and disease relapse, main factors of therapy failure, the design of novel therapeutic approaches targeting these cells may be the only chance for long-term survival in cancer patients. In this sense, their biology and functional properties render LDs excellent candidates for target discovery and design of combined therapeutic strategies. In this review, we summarise the current knowledge identifying LDs and CSCs as main contributors to cancer aggressiveness, metastasis and chemoresistance.

Pharmacological targeting PTK6 inhibits the JAK2/STAT3 sustained stemness and reverses chemoresistance of colorectal cancer

Background

Chemoresistance is the major cause of chemotherapy failure in patients with colorectal cancer (CRC). Protein tyrosine kinase 6 (PTK6) is aberrantly overexpressed in clinical CRC tissues undergoing chemotherapy. We studied if PTK6 contributed to the chemoresistance of CRC in human and mice.

Methods

We obtained tissue samples from patients with CRC and measured the expression of PTK6 by immunohistochemistry. Gain- and loss-of-function assays were performed to study the biological functions of PTK6. We constructed the FLAG-tagged wild type (WT), kinase-dead, and inhibition-defective recombinant mutants of PTK6 to study the effect phosphorylated activation of PTK6 played on CRC cell stemness and chemoresistance. We used small molecule inhibitor XMU-MP-2 to test the influence of PTK6 on sensitivity of CRC cells to 5-FU/L-OHP in both nude mouse and patient-derived xenograft (PDX) animal models.

Results

PTK6 is overexpressed in CRC tissues and plays a stimulatory role in the proliferation and chemoresistance of CRC cells both in vitro and in vivo. PTK6, especially the phosphorylated PTK6, can promote the stemness of CRC cells through interacting with JAK2 and phosphorylating it to activate the JAK2/STAT3 signaling. Pharmacological inhibition of PTK6 using XMU-MP-2 effectively reduces the stemness property of CRC cells and improves its chemosensitivity to 5-FU/L-OHP in both nude mice subcutaneously implanted tumor model and PDX model constructed with NOD-SCID mice.

Conclusions

PTK6 interacts with JAK2 and phosphorylates it to activate JAK2/STAT3 signaling to promote the stemness and chemoresistance of CRC cells. Pharmacological inhibition of PTK6 by small molecule inhibitor dramatically enhances the sensitivity to chemotherapy in nude mice and PDX models.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02059-6.

The interaction between PDCD4 and YB1 is critical for cervical cancer stemness and cisplatin resistance

Cancer multidrug resistance (MDR) is existence in stem cell-like cancer cells characterized by stemness including high-proliferation and self-renewal. Programmed cell death 4 (PDCD4), as a proapoptotic gene, whether it engaged in cancer stemness and cisplatin resistance is still unknown. Here we showed that PDCD4 expressions in Hela/DDP (cisplatin resistance) cells were lower than in parental Hela cells. Moreover, the levels of drug resistance genes and typical stemness markers were markedly elevated in Hela/DDP cells. In vivo, xenograft tumor assay confirmed that knockdown of PDCD4 accelerated the grafted tumor growth. In vitro, colony formation and MTT assay demonstrated that PDCD4 overexpression inhibited cells proliferation in conditions with or without cisplatin. By contrast, PDCD4 deficiency provoked cell proliferation and cisplatin resistance. On mechanism, PDCD4 decreased the protein levels of pAKT and pYB1, accompanied by reduced MDR1 expression. Correspondingly, luciferase reporter assay showed PDCD4 regulated MDR1 promoter activity entirely relied on YB1. Furthermore, Ch-IP, GST-pulldown, and Co-IP assays provided novel evidence that PDCD4 could directly bind with YB1 by the nucleolar localization signal (NOLS) segment, causing the reduced YB1 binding into the MDR1 promoter region through blocking YB1 nucleus translocation, triggering the decreased MDR1 transcription. Taken together, PDCD4-pAKT-pYB1 forms the integrated molecular network to regulate MDR1 transcription during the process of stemness-associated cisplatin resistance.