CD44/CD24 and ALDH1 are widely used cancer stem cell (CSC) markers in breast cancer. However, their expression is not always consistent even in the same subtype of breast cancer. Systematic comparison of their functions is still lacking. We investigated the expression of CD44, CD24 and ALDH1 in different subtypes of breast cancer cells, and explored their relationship with cancer progression. We defined a parameter CD44/CD24 ratio to present the expression level of CD44 and CD24 and found that high CD44/CD24 ratio and ALDH1⁺ are both indicators for cancer malignancy, but play different functions during tumor progression. High CD44/CD24 ratio is more related to cell proliferation and tumorigenesis, which is confirmed by mammosphere formation and tumorigenesis in xenotransplanted mice. ALDH1⁺ is a stronger indicator for cell migration and tumor metastasis. Suppression of CD44 and ALDH1 by siRNA led to decreased tumorigenicity and cell migration capacity. The combination of high CD44/CD24 ratio and ALDH1⁺ would be a more reliable way to characterize CSCs. Moreover, both high CD44/CD24 ratio and ALDH1⁺ were conserved during metastasis, from the primary tumors to the circulating tumor cells (CTCs) and the distant metastases, suggesting the significant value of these CSC markers in assisting cancer detection, prognostic evaluation, and even cancer therapeutics.

Multifunctional nanoplatforms for imaging‐guided synergistic antitumor treatment are highly desirable in biomedical applications. However, anticancer treatment is largely affected by the pre‐existing hypoxic tumor microenvironment (TME), which not only causes the resistance of the tumors to photodynamic therapy (PDT), but also promotes tumorigenesis and tumor progression. Here, a continuous O₂ self‐enriched nanoplatform is constructed for multimodal imaging‐guided synergistic phototherapy based on octahedral gold nanoshells (GNSs), which are constructed by a more facile and straightforward one‐step method using platinum (Pt) nanozyme‐decorated metal–organic frameworks (MOF) as the inner template. The Pt‐decorated MOF@GNSs (PtMGs) are further functionalized with human serum albumin‐chelated gadolinium (HSA‐Gd, HGd) and loaded with indocyanine green (ICG) (ICG‐PtMGs@HGd) to achieve a synergistic PDT/PTT effect and fluorescence (FL)/multispectral optoacoustic tomography (MSOT)/X‐ray computed tomography (CT)/magnetic resonance (MR) imaging. The Pt‐decorated nanoplatform endows remarkable catalase‐like behavior and facilitates the continuous decomposition of the endogenous H₂O₂ into O₂ to enhance the PDT effect under hypoxic TME. HSA modification enhances the biocompatibility and tumor‐targeting ability of the nanocomposites. This TME‐responsive and O₂ self‐supplement nanoparticle holds great potential as a multifunctional theranostic nanoplatform for the multimodal imaging‐guided synergistic phototherapy of solid tumors.

Rationale: Glioma is the most common malignant primary brain tumor in the central nervous system (CNS). The lack of reliable noninvasive diagnostic and prognostic methods is one of the main reasons for the high mortality of glioma. Serum has become a useful biomarker for the diagnosis and prognosis prediction of glioma because extracellular vesicles (EVs) carry molecular components from their parental cells. Methods: To detect EVs and perform molecular analysis of serum EVs, we established and optimized a microbead-assisted method based on flow cytometry and estimated the efficacy of EGFR protein expression and NLGN3 and PTTG1 mRNA in serum EVs from glioma patients (n=23) and healthy individuals (n=12). We evaluated the ability of EGFR+ EVs to differentiate high-grade and low-grade glioma patients and checked the correlation between EGFR in EVs and the ki-67 labeling index (LI) in the tumor tissue. Results: We demonstrated that EGFR+ EVs are effective diagnostic and prognostic markers of glioma. The expression of EGFR in serum EVs can accurately differentiate high-grade and low-grade glioma patients, and EGFR in EVs positively correlates with ki-67 LI in the tumor tissue. We also showed the potential of NLGN3 and PTTG1 mRNA in EVs for detecting glioma patients. Conclusions: We demonstrate that the protein expression of EGFR in serum EVs is an effective diagnostic marker of glioma. EGFR in EVs highly correlates with the malignancy of glioma. We also show the potential of NLGN3 and PTTG1 in EVs for detecting glioma. The optimized flow cytometry with the aid of microbead-based EV enrichment show its potential as a noninvasive method for the detection of glioma and will be beneficial to the management of glioma.