Mammospheres of hormonal receptor positive breast cancer diverge to triple-negative phenotype

CD44 Targeting Mediated by Polymeric Nanoparticles and Combination of Chlorine TPCS2a-PDT and Docetaxel-Chemotherapy for Efficient Killing of Breast Differentiated and Stem Cancer Cells In Vitro

The presence of rare but highly tumorigenic cancer stem cells (CSCs) within the tumors is recognized as one of the major reasons of failure of conventional chemotherapies, mainly attributed to the development of drug resistance and increasing metastatic potential. Here, we propose a therapeutic strategy based on the simultaneous delivery of docetaxel (DTX) and the photosensitizer meso-tetraphenyl chlorine disulfonate (TPCS2a) using hyaluronic acid (HA) coated polymeric nanoparticles (HA-NPs) for the targeting and killing of CD44 over-expressing breast cancer (BC) cells, both differentiated and CSCs (CD44high/CD24low population), thus combining chemotherapy and photodynamic therapy (PDT). Using the CD44high MDA-MB-231 and the CD44low MCF-7 cells, we demonstrated the occurrence of CD44-mediated uptake of HA-NPs both in monolayers and mammosphere cultures enriched in CSCs. Cell treatments showed that combination therapy using co-loaded NPs (HA@DTX/TPCS2a-NPs) had superior efficacy over monotherapies (HA@DTX-NPs or HA@TPCS2a-NPs) in reducing the self-renewal capacity, measured as mammosphere formation efficiency, and in eradicating the CSC population evaluated with aldehyde dehydrogenase activity assay and CD44/CD24 immunostaining. In summary, these in vitro studies demonstrated for the first time the potential of the combination of DTX-chemotherapy and TPCS2a-PDT for killing CSCs using properly designed NPs.

PODXL2 maintains cellular stemness and promotes breast cancer development through the Rac1/Akt pathway

The cluster of differentiation 34 (CD34) family, which includes CD34, podocalyxin-like protein 1 (PODXL), and PODXL2, are type-I transmembrane sialomucins and markers of hematopoietic stem cells (HSCs) and vascular-associated tissues. CD34 family proteins are expressed by endothelial cells and hematopoietic precursors. PODXL is well known to be associated with invadopodia formation and to promote the epithelial-mesenchymal transition, tumor migration and invasion. PODXL expression was correlated with poor survival of cancer patients. However, the role of PODXL2 in cancer has been less fully explored. To reveal the novel role of PODXL2 in breast cancer, the present study evaluated PODXL2 levels in relation to clinical outcomes of cancer patients by performing a bioinformatics analysis using the Oncomine database, Kaplan-Meier plots, and the CCLE database. Empirical validation of bioinformatics predictions was conducted utilizing the short hairpin (sh)-RNA silencing method for PODXL2 in the BT474 invasive ductal breast carcinoma cell line. The bioinformatics analysis revealed that PODXL2 overexpression was correlated with poor survival of breast cancer patients, suggesting an oncogenic role of PODXL2 in breast carcinoma. In a validation experiment, knockdown of PODXL2 in BT474 cells slightly influenced cell proliferation, suppressed migration, and inhibited expressions of downstream molecules, including Ras-related C3 botulinum toxin substrate 1 (Rac1), phosphorylated (p)-Akt (S473), and p-paxillin (Y31) proteins. In addition, knockdown of PODXL2 reduced expression levels of cancer stem cell (CSC) markers, including Oct-4 and Nanog, and the breast CSC marker aldehyde dehydrogenase 1 (ALDH1). Collectively, our present study demonstrated that PODXL2 plays a crucial role in cancer development and could serve as a potential prognostic biomarker in breast cancer patients.

Targeting Breast Cancer Stem Cells: A Methodological Perspective

Cancer Stem Cells (CSCs) constitute a subpopulation at the top of the tumor cell hierarchy that contributes to tumor heterogeneity and is uniquely capable of seeding new tumors. Because of their biological properties, CSCs have been pointed out as therapeutic targets for the development of new therapies against breast cancer. The identification of drugs that selectively target breast CSCs requires a clear understanding of their biological functions and the experimental methods to evaluate such hallmarks. Herein, we review the methods to study breast CSCs properties and discuss their value in the preclinical evaluation of CSC-targeting drugs.

HMGB3 silence inhibits breast cancer cell proliferation and tumor growth by interacting with hypoxia-inducible factor 1α

Background: Breast cancer is the most common malignant tumor that affects women with higher incidence. High-mobility group box 3 (HMGB3) plays critical functions in DNA repair, recombination, transcription and replication. This study aimed to investigate the effects of HMGB3 silence on mammosphere formation and tumor growth of breast cancer.

Methods: LV5-HMGB3 and LV3-siHMGB3 vectors were transfected into MCF10A, MDA-MB-231, HCC1937, ZR-75-1 and MCF7 cells. Cell counting kit-8 (CCK-8) assay was used to evaluate cell proliferation. Xenograft tumor mice model was established by injection of MDA-MB-231. qRT-PCR and western blot were used to examine the expression of Nanog, Sox2 and OCT-4. Mammosphere forming assay was employed to evaluate mammosphere formation both in vivo and in vitro. Dual luciferase assay was utilized to verify the interaction between HMGB3 and hypoxia-inducible factor 1α (HIF1α). CD44⁺/CD24⁻ was assessed with flow cytometry.

Results: HMGB3 expression was higher significantly (p<0.05) in cancer cells compared to normal cells. HMGB3 overexpression significantly (p<0.05) enhanced and HMGB3 silence reduced cell proliferative mice compared to MCF10A and MDA-MB-231, respectively. HMGB3 overexpression enhanced and HMGB3 silence inhibited mammosphere formation. HMGB3 overexpression upregulated and HMGB3 silence downregulated Nanog, SOX2 and OCT-4 genes/proteins in MCF10A and MDA-MB-231 cells, respectively. HMGB3 silence reduced CD44⁺/CD24⁻ levels in cancer cells. Silence of HMGB3 strengthened reductive effects of PTX on tumor sizes, iPSC biomarkers and mammosphere amounts in xenograft tumor mouse models. HMGB3 silence inhibited mammoshpere formation, cell proliferation and CD44⁺CD24⁻ by interacting with HIF1α.

Conclusion: HMGB3 silence could inhibit the cell proliferation in vitro and suppress tumor growth in vivo levels. The antitumor effects of HMGB3 silence were mediated by interacting with the HIF1α.

Antrocin, a bioactive component from Antrodia cinnamomea, suppresses breast carcinogenesis and stemness via downregulation of β-catenin/Notch1/Akt signaling

BACKGROUND

We identified increased β-catenin and Atk expression was associated with drug resistance and poor prognosis in breast cancer patients using public databases. Antrocin treatment suppressed breast tumorigenesis and stemness properties.

HYPOTHESIS/PURPOSE

We aimed to provide preclinical evidence for antrocin, an active component of Antrodia cinnamomea, as a potential small-molecule drug for treating drug-resistant breast cancer.

METHODS

Various in vitro assays including SRB, Boyden chamber, colony formation, drug combination index and tumor sphere generation were used to determine the anti-cancer and stemness effects of antrocin. Mouse xenograft models were used to evaluate antrocin's effect in vivo.

RESULTS

Antrocin treatment suppressed the viability, migration colony formation and mammosphere generation. Antrocin-mediated anti-cancer effects were associated with the decreased expression of oncogenic and stemness markers such as β-catenin, Akt and Notch1. A sequential regimen of antrocin and paclitaxel synergistically inhibit breast cancer viability in vitro and in vivo.

CONCLUSION

Our preclinical evidence supports antrocin's ability of inhibiting tumorigenic and stemness properties in breast cancer cells. Further develop of antrocin should be encouraged; the combined use of antrocin and paclitaxel may also be considered for future clinical trials.