Prognostic significance of CD24 protein expression in patients treated with adjuvant radiotherapy after radical hysterectomy for cervical squamous cell carcinoma

CD24, A Review of its Role in Tumor Diagnosis, Progression and Therapy

CD24, is a mucin-like GPI-anchored molecules. By immunohistochemistry, it is widely detected in many solid tumors, such as breast cancers, genital system cancers, digestive system cancers, neural system cancers and so on. The functional roles of CD24 are either fulfilled by combination with ligands or participate in signal transduction, which mediate the initiation and progression of neoplasms. However, the character of CD24 remains to be intriguing because there are still opposite voices about the impact of CD24 on tumors. In preclinical studies, CD24 target therapies, including monoclonal antibodies, target silencing by RNA interference and immunotherapy, have shown us brighten futures on the anti-tumor application. Nevertheless, evidences based on clinical studies are urgently needed. Here, with expectancy to spark new ideas, we summarize the relevant studies about CD24 from a tumor perspective.

The signal transducer CD24 suppresses the germ cell program and promotes an ectodermal rather than mesodermal cell fate in embryonal carcinomas

Testicular germ cell tumors (GCTs) are stratified into seminomas and nonseminomas. Seminomas share many histological and molecular features with primordial germ cells, whereas the nonseminoma stem cell population—embryonal carcinoma (EC)—is pluripotent and thus able to differentiate into cells of all three germ layers (teratomas). Furthermore, ECs are capable of differentiating into extra‐embryonic lineages (yolk sac tumors, choriocarcinomas). In this study, we deciphered the molecular and (epi)genetic mechanisms regulating expression of CD24, a highly glycosylated signaling molecule upregulated in many cancers. CD24 is overexpressed in ECs compared with other GCT entities and can be associated with an undifferentiated pluripotent cell fate. We demonstrate that CD24 can be transactivated by the pluripotency factor SOX2, which binds in proximity to the CD24 promoter. In GCTs, CD24 expression is controlled by epigenetic mechanisms, that is, histone acetylation, since CD24 can be induced by the application histone deacetylase inhibitors. Vice versa, CD24 expression is downregulated upon inhibition of histone methyltransferases, E3 ubiquitin ligases, or bromodomain (BRD) proteins. Additionally, three‐dimensional (3D) co‐cultivation of EC cells with microenvironmental cells, such as fibroblasts, and endothelial or immune cells, reduced CD24 expression, suggesting that crosstalk with the somatic microenvironment influences CD24 expression. In a CRISPR/Cas9 deficiency model, we demonstrate that CD24 fulfills a bivalent role in differentiation via regulation of homeobox, and phospho‐ and glycoproteins; that is, it is involved in suppressing the germ cell/spermatogenesis program and mesodermal/endodermal differentiation, while poising the cells for ectodermal differentiation. Finally, blocking CD24 by a monoclonal antibody enhanced sensitivity toward cisplatin in EC cells, including cisplatin‐resistant subclones, highlighting CD24 as a putative target in combination with cisplatin.

Increased Expression of Oct4, Nanog and CD24 Predicts Poor Response to Chemo-Radiotherapy and Unfavourable Prognosis in Locally Advanced Oral Squamous Cell Carcinoma

Background:

Current study investigates the role of Oct4, Nanog and CD24 in locally-advanced oral squamous cell carcinoma (OSCC), to evaluate whether the expression of these markers can predict efficacy of neoadjuvant-chemo-radiotherapy and survival of patients.

Methods:

Biomarker expression was evaluated in 50 homogenously treated patients of locally-advanced OSCC.

Results:

Clinical response was complete in 30% (n=15), partial response in 46% (n=23), no response in 24% (n=12). Pathologically, 74% patents (n=37) were responders and 26% were non-responders (n=13). Biomarker-overexpression was seen in 46% cases for Oct4, 54% cases for Nanog and 58% cases for CD24. Oct4, Nanog and CD24 expression showed significant correlation with clinical and pathological response (p<0.05). Three year recurrence-free survival was 71%, overall survival was 66%. Post-treatment advanced pathological N (ypN), post treatment advanced pathological TNM (ypTNM) stage, clinical non-response, pathologic non-response, positive/high expression of all three biomarkers had a significant negative impact on recurrence-free and overall survival.

Conclusions:

Expressions of Oct4, Nanog and CD24 have significant association with treatment response and survival in patients with locally advanced OSCC treated with neoadjuvant chemo-radiation. Survival of these patients is significantly affected by ypN stage, ypTNM stage, expression of all three biomarkers, clinical and pathological response to neoadjuvant therapy.

Efficient isolation, culture, purification, and stem cell expression profiles of primary tumor cells derived from uterine cervical squamous cell carcinoma

PROBLEM

Since not too many human uterus cervical squamous cell carcinoma (CSCC) cell lines in existence, efficient isolation, culture, and purification protocols for primary CSCC cells were optimized as a tool for the study of uterus CSCC.

METHOD OF STUDY

The protocols for partial multiple enzymatic digestion and explant cell culture were combined and then the resulting mixed cell component cultures were purified by magnetic-activated cell sorting. Colony-forming assay was utilized for detection of cell carcinogenesis potential, and immunofluorescence was used to detect protein expression of CSCC. Finally, flow cytometry (FCM) was performed to analyze cancer stem cells (CSCs) phenotypic markers as well as programmed cell death ligand 1(PD-L 1).

RESULTS

Freshly isolated cells containing tumor cells and cancer-associated fibroblasts (CAFs) efficiently proliferate to 85% confluence on a 6 cm petri dish in 5-7 days. Anti-epithelial cell adhesion molecule antibody (EpCAM) microbeads were used to successfully separate a homogeneous subpopulation of epithelial tumor cells. Both EpCAM+ and EpCAM- cell subpopulations were able to be passaged more than 30 times. Proportions of tumor cell populations expressed CSCs markers such as CD133, CD24, aldehyde dehydrogenase 1 (ALDH1), and CD44. The vimentin+ & EpCAM- population, defined with CAFs, could express CD146 mesenchymal stem cells marker. Meanwhile, PD-L 1 was identified in most subpopulation of CD44+ cells at low passage numbers.

CONCLUSION

Efficient isolation, culture, and purification protocols for primary CSCC cells were successfully built. Additionally, the profiling of CSCs cell markers might provide promising therapeutic targets and clinic strategies.

Potential role of cancer stem cells as biomarkers and therapeutic targets in cervical cancer

BACKGROUND

Eradicating cancer stem cells (CSCs) that are termed as the "beating heart" of various malignant tumors, including cervical cancer, holds great importance in cancer therapeutics. CSCs not only confer chemo-radio resistance but also play an important role in tumor metastasis and thereby pose a potential barrier for the cure of cervical cancer. Cervical cancer, a common malignancy among females, is associated with high morbidity and mortality rates, and the study on CSCs residing in the niche is promising.

RECENT FINDINGS

Biomarker approach to screen the cervical CSCs has gained impetus since the past decade. Progress in identification and characterization of the stem cell biomarkers has led to many insights. For the diagnostic purpose, several biomarkers like viral (HPV16), stem cell markers, transcription factors (viz, SOX2, OCT 4, and c-Myc), and CSC surface markers (viz, ALDH1 and CD44) have been identified. The research so far has been directed to study the CSC stemness and demonstrates various gene expression signatures in cervical CSCs. Such studies hold a potential to improve diagnostic accuracy and predict therapeutic response and clinical outcome in patients.

CONCLUSIONS

Stem cell biomarkers have been validated and their therapeutic targets are being developed as "strategies to improve therapeutic ratio in personalized medicine." This review gives a brief overview of the cervical CSC biomarkers, their current and future diagnostic, prognostic, and therapeutic potential.

CD24 isoform a promotes cell proliferation, migration and invasion and is downregulated by EGR1 in hepatocellular carcinoma

Introduction

CD24 is known as a heavily glycosylated cell surface molecule that is highly expressed in a wide variety of human malignancies. Previous studies have shown that CD24 plays an important role in self-renewal, proliferation, migration, invasion and drug resistance of hepatocellular carcinoma (HCC). However, little is known about the expression and function of CD24 isoform a (CD24A) and CD24 isoform b (CD24B) in HCC.

Materials and methods

Quantitative real-time polymerase chain reaction (qPCR) and Western blotting were performed to detect CD24 and EGR1 expression in HCC cells and tissue. The function of CD24 in cell proliferation was verified with MTT assays, colony formation assays and tumor xenograft models. Wound healing assays and invasion assays were performed to clarify the function of CD24 in the regulation of cell migration and invasion in HCC. A dual luciferase reporter assay and chromatin immunoprecipitation assay were used to analyze the regulation mechanism of CD24A.

Results

CD24A but not CD24B, which was barely detected by qPCR and Western blotting, is significantly upregulated in HCC tissue. Both CD24A and CD24B contribute to HCC cell proliferation, migration and invasion, but CD24A is more effective than CD24B. EGR1 downregulates CD24A and exerts transcription-promoting activity on the CD24A promoter. Furthermore, EGR1 represses HCC cell proliferation via downregulation of CD24A.

Conclusion

CD24A is the predominant CD24 isoform in HCC and plays a major role in cell proliferation, migration, and invasion. EGR1 can exert its antitumor effect through transcriptional downregulation of CD24A in HCC.

CD24 regulates sorafenib resistance via activating autophagy in hepatocellular carcinoma

Hepatocellular carcinoma is one of most common solid cancers worldwide. Sorafenib is indicated as a treatment for advanced hepatocellular carcinoma (HCC). However, the clinical efficacy of sorafenib has been severely compromised by the development of drug resistance, and the precise mechanisms of drug resistance remain largely unknown. Here we found that a cell surface molecule, CD24, is overexpressed in tumor tissues and sorafenib-resistant hepatocellular carcinoma cell lines. Moreover, there is a positive correlation between CD24 expression levels and sorafenib resistance. In sorafenib-resistant HCC cell lines, depletion of CD24 caused a notable increase of sorafenib sensitivity. In addition, we found that CD24-related sorafenib resistance was accompanied by the activation of autophagy and can be blocked by the inhibition of autophagy using either pharmacological inhibitors or essential autophagy gene knockdown. In further research, we found that CD24 overexpression also leads to an increase in PP2A protein production and induces the deactivation of the mTOR/AKT pathway, which enhances the level of autophagy. These results demonstrate that CD24 regulates sorafenib resistance via activating autophagy in HCC. This is the first report to describe the relationships among CD24, autophagy, and sorafenib resistance. In conclusion, the combination of autophagy modulation and CD24 targeted therapy is a promising therapeutic strategy in the treatment of HCC.

High ratio of programmed cell death protein 1 (PD-1)(+)/CD8(+) tumor-infiltrating lymphocytes identifies a poor prognostic subset of extrahepatic bile duct cancer undergoing surgery plus adjuvant chemoradiotherapy

BACKGROUND AND PURPOSE

This study investigated the prognostic role of PD-L1 expression, PD-1(+) tumor-infiltrating lymphocytes (TILs), and the ratio of PD-1(+)/CD8(+) TILs in extrahepatic bile duct (EHBD) cancer.

MATERIALS AND METHODS

We analyzed 83 patients with EHBD cancer who underwent curative surgery plus fluoropyrimidine-based chemoradiotherapy (CRT). Expressions of PD-L1, PD-1, and CD8 were assessed by immunohistochemistry.

RESULTS

Fifty-six (68%) patients were PD-L1-positive, and its lower expression level was associated with hilar tumor location (P=0.044). A higher ratio of PD-1(+)/CD8(+) TILs was associated with poorer overall survival (OS) (P=0.032), relapse-free survival (RFS) (P=0.024), and distant metastasis-free survival (DMFS) (P=0.039) in Kaplan-Meier analyses, but survival differences were not observed according to the PD-L1 expression level. With Cox proportional hazards models, the ratio of PD-1(+)/CD8(+) TILs was the independent prognostic factor in OS (HR 2.47, 95% CI 1.04-5.86), RFS (HR 2.41, 95% CI 1.08-5.41), and DMFS (HR 2.67, 95% CI 1.00-7.11) after adjusting for other significant clinicopathologic variables.

CONCLUSION

A strong survival impact of the ratio of PD-1(+)/CD8(+) TILs was observed in EHBD cancer. In the poor prognostic subgroup, the blockade of the immune checkpoint in combination with conventional multimodality treatment needs to be considered.

Report on the International Workshop 'Cancer stem cells: the mechanisms of radioresistance and biomarker discovery'

The aim of the Workshop "Cancer stem cells: The mechanisms of radioresistance and biomarker discovery", which was held on 23-24 September 2013 at OncoRay - National Center for Radiation Research in Oncology in Dresden, Germany, was to bring together the most recent viewpoints and insights about: (i) the molecular characterization and regulation of CSC, (ii) the mechanisms of CSC radioresistance, and (iii) the discovery of new CSC targeting therapeutics and biomarkers. In this report some research aspects presented in these three topics are highlighted.

Cluster of differentiation 24 expression is an independent prognostic factor of adverse outcome in cervical carcinoma

OBJECTIVE

Cluster of differentiation (CD) 24 is a cell adhesion molecule that has been implicated in tumor invasion and metastasis of various solid tumors. The aim of this study was to explore the expression patterns of CD24 as a predictive marker for long-term survival in cervical carcinomas.

METHODS

A total of 144 patients diagnosed with International Federation of Gynecology and Obstetrics stage I to IV cervical carcinoma were studied, and 95 patients underwent surgical intervention. The expression of CD24 protein was studied by immunohistochemistry using tissue microarrays.

RESULTS

Overexpression of CD24 was observed in 50 (34.7%) of 144 invasive carcinomas. Patients with CD24 overexpression had poorer survival compared with that of patients with CD24 underexpression (5-year survival rate, 52.0% vs 72.3%; log rank P = 0.014). Importantly, in multivariate analysis, CD24 overexpression proved to be a significant independent predictor of short-term survival (relative risk, 1.814; P = 0.043).

CONCLUSIONS

The present study suggests that CD24 overexpression is a predictor of decreased long-term survival in patients with cervical carcinoma. Therefore, immunohistochemical evaluation of CD24 expression is a potential prognostic biomarker for cervical carcinomas.

Clinical perspectives of cancer stem cell research in radiation oncology

Radiotherapy has a proven potential to eradicate cancer stem cells which is reflected by its curative potential in many cancer types. Considerable progress has been made in identification and biological characterisation of cancer stem cells during the past years. Recent biological findings indicate significant inter- and intratumoural and functional heterogeneity of cancer stem cells and lead to more complex models which have potential implications for radiobiology and radiotherapy. Clinical evidence is emerging that biomarkers of cancer stem cells may be prognostic for the outcome of radiotherapy in some tumour entities. Perspectives of cancer stem cell based research for radiotherapy reviewed here include their radioresistance compared to the mass of non-cancer stem cells which form the bulk of all tumour cells, implications for image- and non-image based predictive bio-assays of the outcome of radiotherapy and a combination of novel systemic treatments with radiotherapy.

Cancer stem cell phenotype relates to radio-chemotherapy outcome in locally advanced squamous cell head-neck cancer

Background:

Cancer stem cells (CSCs) tend to repopulate malignant tumours during radiotherapy and, therefore, prolongation of the overall treatment time may result in radiotherapy failure. Thus, an estimate of the number of CSCs in tumour biopsies may prove most useful in predicting resistance to radiotherapy and a guide for development therapies aimed to eradicate a cancer cell population with effects on radiotherapy-related cancer regrowth.

Methods:

The CSC population was investigated semi-quantitatively in 74 locally advanced squamous cell head–neck cancers (HNSCC) from an equal number of patients, treated with accelerated platinum-based radiotherapy. A standard immunohistochemical technique and the CSC markers CD44, CD24, Oct4, integrin-β1 and aldehyde dehydrogenase isoform 1A1 (ALDHA1) was used, in parallel with the proliferation marker MIB-1. The results were correlated with the site of the tumour, the MIB-1 index, the tumour grade and stage, and prognosis.

Results:

The expression of CD44, CD24 and Oct4 were significantly associated with the MIB-1 proliferation index. In addition, the CD44 was linked with the better differentiated HNSCC. The CD44, Oct4 and integrin-β1 were all associated with poor prognosis but, in a multivariate analysis, the integrin-β1 had an independent statistical significance in terms of local relapse, distant metastases and overall survival. Interestingly, ALDH1 was associated with favourable prognosis.

Conclusion:

CSC markers are linked with poor radiotherapy outcome in HNSCC, with integrin-β1 being the strongest and independent prognostic factor. Targeting CSC molecules with monoclonal antibodies or pharmaceutical agents may prove important for the treatment of HNSCC.