POMC maintains tumor-initiating properties of tumor tissue-derived long-term-cultured breast cancer stem cells

Advancing biomarker development for diagnostics and therapeutics using solid tumour cancer stem cell models

The cancer stem cell model hopes to explain solid tumour carcinogenesis, tumour progression and treatment failure in cancers. However, the cancer stem cell model has led to minimal clinical translation to cancer stem cell biomarkers and targeted therapies in solid tumours. Many reasons underlie the challenges, one being the imperfect understanding of the cancer stem cell model. This review hopes to spur further research into clinically translatable cancer stem cell biomarkers through first defining cancer stem cells and their associated models. With a better understanding of these models there would be a development of more accurate biomarkers. Making the clinical translation of biomarkers into diagnostic tools and therapeutic agents more feasible.

Prognostic Score Model Based on Ten Differentially Methylated Genes for Predicting Clinical Outcomes in Patients with Adenocarcinoma of the Colon

Purpose

We aimed to screen novel genetic biomarkers for use in a prognostic score (PS) model for the accurate prediction of survival outcomes for patients with colon adenocarcinoma (COAD).

Methods

Gene expression and methylation data were downloaded from The Cancer Genome Atlas database, and the samples were randomly divided into training and validation sets for the screening of differentially methylated genes (DMGs) and differentially expressed genes (DEGs). Co-methylated genes were screened using weighted gene co-expression network analysis. Functional enrichment analysis was performed using the Database for Annotation, Visualization, and Integrated Discovery. Univariate and multivariate Cox regression analyses were performed to identify prognosis-related genes and clinical factors. Receiver operating characteristic curve analysis was carried out to evaluate the predictive performance of the PS model.

Results

In total, 1434 DEGs and 1038 DMGs were screened in the training set, among which 284 were found to be overlapping genes. For 127 of these overlapping genes, the methylation and expression levels were significantly negatively correlated. An optimal signature from 10 DMGs was identified to construct the PS model. Patients with a high PS seemed to have worse outcomes than those with a low PS. Moreover, cancer recurrence and the PS model status were independent prognostic factors.

Conclusion

This PS model based on an optimal 10-gene signature would help in the stratification of patients with COAD and improve the assessment of their clinical outcomes.

β-endorphin at the intersection of pain and cancer progression: Preclinical evidence

We examined the association between endogenous opioid β-endorphin, cancer progression and pain in a transgenic mouse model of breast cancer, with a rat C3(1) simian virus 40 large tumor antigen fusion gene (C3TAg). C3TAg mice develop ductal epithelial atypia at 8 weeks, progression to intra-epithelial neoplasia at 12 weeks, and invasive carcinoma with palpable tumors at 16 weeks. Consistent with invasive carcinoma at 4 months of age, C3TAg mice demonstrate a significant increase in hyperalgesia compared to younger C3TAg or control FVBN mice without tumors. Our data show that the growing tumor contributes to circulating β-endorphin. As an endogenous ligand of mu opioid receptor, β-endorphin has analgesic activity. Paradoxically, we observed an increase in pain in transgenic breast cancer mice with significantly high circulating and tumor-associated β-endorphin. Increased circulating β-endorphin correlates with increasing tumor burden. β-endorphin induced the activation of mitogenic and survival-promoting signaling pathways, MAPK/ERK 1/2, STAT3 and Akt, observed by us in human MDA-MB-231 cells suggesting a role for β-endorphin in breast cancer progression and associated pain.

Protein anabolism is key to long-term survival in high-grade serous ovarian cancer

This study aimed to identify the biological processes associated with long-term survival in high-grade serous ovarian cancer (HGSOC). HGSOC cases obtained from The Cancer Genome Atlas Ovarian Cancer (TCGA-OV) database were divided into long-term survivors (LTS) and normal-term survivors (NTS) based on survival cutoffs defined by the HGSOC cohort in the SEER database. Differentially expressed genes (DEGs) were screened using the generalized linear modeling (GLM) method. Gene Ontology (GO) functional and KEGG pathway enrichment analyses were performed using DAVID Bioinformatics Resources. DEG-related protein-protein interactions (PPI) were extracted from the STRING database and hub genes were identified using CytoHubba in the Cytoscape program. In total, 157 DEGs, including 155 upregulated and 2 downregulated genes, were identified. Upregulated genes were statistically enriched in 80 GO terms and 11 KEGG pathways related to energy and substrate metabolism, such as protein absorption, digestion, and metabolism as well as signaling pathways, including chromatin silencing, regulation of ERK1 and ERK2 cascade, and regulation of MAPKKK. ALB and POMC were the common hub genes. These findings reveal that protein anabolism is crucial to long-term survival, regulated by activation of the MAPK/ERK signaling pathway and chromatin silencing. Comprehensive understanding of the molecular mechanisms via further exploration may contribute toward an effective treatment for ovarian cancer.

miR-376c-3p modulates the properties of breast cancer stem cells by targeting RAB2A

MicroRNAs (miRNAs/miRs) negatively regulate gene expression and participate in various cellular processes. miRNA dysregulation is associated with cancer progression. The present study aimed to identify the miRNAs that participate in breast cancer tumorigenesis and determine the mechanism that underlies this. miRNA microarray data analysis and validation assays indicated that miR-376c-3p was downregulated in breast tumour tissues and breast cancer stem cells (BCSCs) compared with adjacent non-cancerous tissues and MCF-10A cells, respectively. Ras-related protein Rab-2A (RAB2A) was predicted as a target of miR-376c-3p, which was confirmed by conducting further experiments. miR-376c-3p regulated the BCSC population and the expression of stem cell regulatory genes by targeting RAB2A. By performing mammosphere, Cell Counting Kit-8, colony formation and transwell invasion assays, it was demonstrated that miR-376c-3p also inhibited BCSC self-renewal, proliferation and invasion by regulating RAB2A expression. Using a xenograft mouse model, it was revealed that miR-376c-3p overexpression suppressed breast cancer growth in vivo. In conclusion, the results indicated that miR-376c-3p targeted RAB2A to regulate BCSC fate and properties; therefore, miR-376c-3p may serve as a potential therapeutic target for breast cancer.

TV-circRGPD6 Nanoparticle Suppresses Breast Cancer Stem Cell-Mediated Metastasis via the miR-26b/YAF2 Axis

Metastatic tumor is a major contributor to death caused by breast cancer. However, effective and targeted therapy for metastatic breast cancer remains to be developed. Initially, we exploited a feasible biological rationale of the association between metastatic status and tumor-initiating properties in metastatic breast cancer stem cells (BCSCs). Further, we explored that circular RNA RANBP2-like and GRIP domain-containing protein 6 (circRGPD6) regulates the maintenance of stem cell-like characteristics of BCSCs. Targeted expression of circRGPD6 via human telomerase reverse transcriptase (hTERT) promoter-driven VP16-GAL4-woodchuck hepatitis virus post-transcriptional regulatory element (WPRE)-integrated systemic amplifier delivery composite vector (TV-circRGPD6) significantly inhibited expression of stem-cell marker CD44 and increased expression of the DNA damage marker p-H2AX. Furthermore, we determined TV-circRGPD6, alone or synergized with docetaxel, displays significant therapeutic responses on metastatic BCSCs. Mechanistic analyses exploited that TV-circRGPD6 suppresses BCSC-mediated metastasis via the microRNA (miR)-26b/YAF2 axis. Clinically, for the first time, we observed that expressions of circRGPD6 and YAF2 predict a favorable prognosis in patients with breast cancer, whereas expression of miR-26b is an unfavorable prognostic factor. Overall, we have developed a TV-circRGPD6 nanoparticle that selectively expresses circRGPD6 in metastatic BCSCs to eradicate breast cancer metastasis, therefore providing a novel avenue to treat breast cancers.

Highly-expressed P2X7 receptor promotes growth and metastasis of human HOS/MNNG osteosarcoma cells via PI3K/Akt/GSK3β/β-catenin and mTOR/HIF1α/VEGF signaling

The P2X7 receptor, an ATP‐gated ion channel, is critical for cancer cell growth, invasiveness, and angiogenesis. Previous studies indicate that P2X7 regulates osteoblast proliferation and osteodeposition and that high P2X7 expression has a pro‐growth effect in osteosarcoma. However, how it functions in osteosarcoma cell growth and metastasis is not clear. Thus, we elucidated molecular mechanisms of P2X7‐dependent positive regulation of osteosarcoma cell proliferation, invasion, migration, epithelial to mesenchymal transition (EMT), and angiogenesis using in vitro and in vivo models. We confirm that P2X7 is highly‐expressed in human osteosarcoma tumor tissues and HOS/MNNG, MG63, U2OS, SW1353 and SAOS‐2 cell lines. P2X7 receptor stimulation enhanced HOS/MNNG and SAOS‐2 cell proliferation, migration and invasion; but knockdown of P2X7 expression or receptor inhibition had opposite effects. P2X7 positively regulated glycogen content, epithelial to mesenchymal transition and stemness of HOS/MNNG cells. P2X7 activation promoted PI3K/Akt/GSK3β/β‐catenin and mTOR/HIF1α/VEGF signaling, thereby mediating pro‐tumor effects of osteosarcoma cells. Consistent with data from in vitro experiments, systemic administration of P2X7 agonist induced tumor growth, metastasis and tumor‐associated bone destruction in osteosarcoma‐bearing nude mice, whereas a P2X7 antagonist reversed these effects. Thus, the P2X7 receptor participates in regulation of osteosarcoma growth and metastasis and we offer evidence that P2X7 may be a promising therapeutic target for treating osteosarcoma.

What's new?

The ATP‐gated ion channel receptor P2X7 is increasingly recognized as a tumor‐promoting factor. In this study, P2X7 was found to be overexpressed in human osteosarcoma tissues and cells, with its activation enhancing osteosarcoma cell proliferation, migration, and invasion. P2X7 activation further induced epithelial‐mesenchymal transition (EMT), affected the stemness of osteosarcoma cells, and augmented angiogenesis. Experiments in mice showed that P2X7 also induces osteosarcoma‐associated bone destruction. Opposing effects were observed upon P2X7 inhibition. P2X7 activity was influenced in part by PI3K/Akt/GSK3β/β‐catenin and mTOR/HIF1α/VEGF signaling pathways. The data identify P2X7 as a target for the development of novel therapeutics against osteosarcoma.

Proton Sensitivity of Corticotropin-Releasing Hormone Receptor 1 Signaling to Proopiomelanocortin in Male Mice

Because an acidic cellular microenvironment is engendered by inflammation and may determine cell differentiation, we elucidated the impact of acidic conditions on induction of proopiomelanocortin (POMC) expression. Here, we demonstrate mechanisms for proton sensitivity of CRH receptor 1 (CRHR1) signaling to POMC and ACTH production. Low pH (6.8) resulted in doubling of POMC expression and ACTH production in pituitary cell line AtT-20 and in primary mouse pituitary cells. Using CRISPR knockout, we show that CRHR1 is necessary for acid-induced POMC expression, and this induction is mediated by CRHR1 histidine residues and calmodulin-dependent protein kinase II in both pituitary corticotroph cells and in nonpituitary cell lines expressing ectopic ACTH. In contrast, CRH ligand binding affinity to CRHR1 was decreased with acidic pH, implying that proton-induced POMC expression prevails in acidic conditions independently of CRH ligand binding. The results indicate that proton-induced CRHR1 signaling regulates ACTH production in response to an acidic microenvironment.

Nanoparticle Delivery of miR-34a Eradicates Long-term-cultured Breast Cancer Stem Cells via Targeting C22ORF28 Directly

Rationale: Cancer stem cells (CSCs) have been implicated as the seeds of therapeutic resistance and metastasis, due to their unique abilities of self-renew, wide differentiation potentials and resistance to most conventional therapies. It is a proactive strategy for cancer therapy to eradicate CSCs. Methods: Tumor tissue-derived breast CSCs (BCSC), including XM322 and XM607, were isolated by fluorescence-activated cell sorting (FACS); while cell line-derived BCSC, including MDA-MB-231.SC and MCF-7.SC, were purified by magnetic-activated cell sorting (MACS). Analyses of microRNA and mRNA expression array profiles were performed in multiple breast cell lines. The mentioned nanoparticles were constructed following the standard molecular cloning protocol. Tissue microarray analysis has been used to study 217 cases of clinical breast cancer specimens. Results: Here, we have successfully established four long-term maintenance BCSC that retain their tumor-initiating biological properties. Our analyses of microarray and qRT-PCR explored that miR-34a is the most pronounced microRNA for investigation of BCSC. We establish hTERT promoter-driven VISA delivery of miR-34a (TV-miR-34a) plasmid that can induce high throughput of miR-34a expression in BCSC. TV-miR-34a significantly inhibited the tumor-initiating properties of long-term-cultured BCSC in vitro and reduced the proliferation of BCSC in vivo by an efficient and safe way. TV-miR-34a synergizes with docetaxel, a standard therapy for invasive breast cancer, to act as a BCSC inhibitor. Further mechanistic investigation indicates that TV-miR-34a directly prevents C22ORF28 accumulation, which abrogates clonogenicity and tumor growth and correlates with low miR-34 and high C22ORF28 levels in breast cancer patients. Conclusion: Taken together, we generated four long-term maintenance BCSC derived from either clinical specimens or cell lines, which would be greatly beneficial to the research progress in breast cancer patients. We further developed the non-viral TV-miR-34a plasmid, which has a great potential to be applied as a clinical application for breast cancer therapy.