p75 neurotrophin receptor: A potential surface marker of tongue squamous cell carcinoma stem cells

Proteomic methods identified P75 as marker of poor prognosis in pleuropulmonary blastoma

OBJECTIVES

To study the causes of the rapid progression of pleuropulmonary blastoma and to identify molecular markers related to its prognosis.

MATERIALS AND METHODS

Three pairs of fresh frozen samples of pleuropulmonary blastoma tumors and adjacent normal tissues were analyzed for proteomics, focusing on the protein molecules with significantly increased expression in tumor tissues and related to the cell cycle and DNA replication. The top five protein molecules were selected and verified by immunohistochemistry. To analyze the correlation between the expression of verified protein molecules in pleuropulmonary blastoma and early recurrence/metastasis of pleuropulmonary blastoma.

RESULTS

Compared with the adjacent normal tissues, 1759 proteins were upregulated and 967 proteins were downregulated in pleuropulmonary blastoma. The top five proteins related to the cell cycle and DNA replication were ORC2, P75, Skp2, MCM4 and PCNA. However, only P75, MCM4 and PCNA were upregulated in pleuropulmonary blastoma as determined by immunohistochemistry. Further analysis showed that the expression of P75 in the recurrence/metastasis group was significantly higher than that in the no recurrence/metastasis group, while the expression of MCM4 and PCNA was not significantly different between the recurrence/metastasis group and the no recurrence/metastasis group.

CONCLUSIONS

MCM4, PCNA and P75 may all play an important role in the progression of pleuropulmonary blastoma. Among them, P75 is related to the prognosis and may be used as a marker to predict the prognosis of pleuropulmonary blastoma.

Pilot Investigation on p75ICD Expression in Laryngeal Squamous Cell Carcinoma

We investigated the p75 Neurotrophin Receptor (p75NTR) expression and cleavage product p75NTR Intracellular Domain (p75ICD) as potential oncogenic and metastatic markers in human Laryngeal Squamous Cell Carcinoma (LSCC). p75NTR is highly expressed in Cancer Stem Cells (CSCs) of the laryngeal epithelia and it has been proposed as a marker for stemness, cell migration, and chemo-resistance in different squamous carcinomas. To investigate the clinical significance of p75NTR cleavage products in solid tumors, full-length and cleaved p75NTR expression was analyzed in laryngeal primary tumors from different-stage LSCC patients, diagnosed at the Policlinico Umberto I Hospital. Molecular and histological techniques were used to detect the expressions of p75NTR and p75ICD, and ATP Binding Cassette Subfamily G Member 2 (ABCG2), a CSC marker. We found regulated p75NTR cleavage during squamous epithelial tumor progression and tissue invasion. Our preliminary investigation suggests p75ICD expression and localization as possible features of tumorigenesis and metastaticity. Its co-localization with ABCG2 in squamous cells in the parenchyma invaded by the tumor formation allows us to hypothesize p75NTR and p75ICD roles in tumor invasion and CSC spreading in LSCC patients. These data might represent a starting point for a comprehensive analysis of p75NTR cleavage and of its clinical relevance as a potential molecular LSCC signature, possibly helping diagnosis, and improving prognosis and personalized therapy.

Cancer stem cells enrichment with surface markers CD271 and CD44 in human head and neck squamous cell carcinomas

Head and neck squamous cell carcinoma (HNSCC) has a poor 5-year survival rate of 50%. One potential reason for treatment failure is the presence of cancer stem cells (CSCs). Several cell markers, particularly CD44, have been used to isolate CSCs. However, isolating a pure population of CSC in HNSCC still remains a challenging task. Recent findings show that normal oral stem cells were isolated using CD271 as a marker. Thus, we investigated the combined use of CD271 and CD44 to isolate an enriched subpopulation of CSCs, followed by their characterization in vitro, in vivo, and in patients' tissue samples. Fluorescent-activated cell sorting was used to isolate CD44+/CD271+ and CD44+/CD271- from two human HNSCC cell lines. Cell growth and self-renewal were measured with MTT and sphere/colony formation assays. Treatment-resistance was tested against chemotherapy (cisplatin and 5-fluorouracil) and ionizing radiation. Self-renewal, resistance, and stemness-related genes expression were measured with qRT-PCR. In vivo tumorigenicity was tested with an orthotopic immunodeficient mouse model of oral cancer. Finally, we examined the co-localization of CD44+/CD271+ in patients' tissue samples. We found that CD271+ cells were a subpopulation of CD44+ cells in human HNSCC cell lines and tissues. CD44+/CD271+ cells exhibited higher cell proliferation, sphere/colony formation, chemo- and radio-resistance, upregulation of CSCs-related genes, and in vivo tumorigenicity when compared to CD44+/CD271- or the parental cell line. These cell markers showed increased expression in patients with the increase of the tumor stage. In conclusion, using both CD44 and CD271 allowed the isolation of CSCs from HNSCC. These enriched CSCs will be more relevant in future treatment and HNSCC progression studies.

The current markers of cancer stem cell in oral cancers

Head and neck cancer (HNC) constitute 5% of all reported cancers. Among all, the oral cavity cancer is the most frequent type of HNC which accounts for over half of HNC cases. Mouth cancer ranks the sixth leading cause of cancer-related mortality. Generally, conventional chemotherapy has shown success at decreasing relapse and metastasis rates and improves the overall prognosis. Recently, target therapy and targeted drug delivery systems have been introduced as promising treatments. The elimination of efficiency of current therapeutic strategies due to the spared cancer stem cells that cause chemotherapy resistance, relapse and metastasis. Inefficiency methodologies in the elimination of all cancer cells in the body are a major problem that remained to be resolved before to confront the new cancer therapies. Many studies imply to cancer stem cell markers as important agents for targeted anti-cancer as well as improving chemotherapy efficiencies. The potentials of targeted cancer therapy led us to search for novel markers in the mouth cancer stem cells especially in rare cancers. The aimed of this research was, first a comprehensive critical review of the previous studies on the markers of cancer stem cells in oral cancers including oral squamous cell carcinoma, salivary gland cancers, and to highlight the most common cancer stem cell markers which have potential to be exploited as indicators for the preneoplastic lesion malignancy, oral cancer progression, and/or treatment prognosis.

Immunohistochemistry profile of p75 neurotrophin receptor in oral epithelial dysplasia and oral squamous cell carcinoma induced by 4-nitroquinoline 1-oxide in rats

OBJECTIVE

The 4-nitroquinoline 1-oxide (4-NQO) model for carcinogenesis has been used to investigate cancer stem cells (CSC), but no study has addressed the role of the p75 neurotrophin receptor (p75NTR) in 4-NQO-induced oral dysplasia and oral squamous cell carcinoma (OSCC). The aim of this study was to evaluate the immunohistochemistry profile of the p75NTR during 4-NQO-induced oral carcinogenesis in rats and to verify whether this profile has an association with proliferating cell nuclear antigen (PCNA) immunolabeling.

DESIGN

For 28 weeks, rats were exposed to 4-NQO, which was diluted in the drinking water. After 3, 5, 7, 16, and 28 weeks, the animals were euthanized and their tongues were histologically analyzed using p75NTR and PCNA immunolabeling.

RESULTS

In animals without 4-NQO exposure, the p75NTR and PCNA were expressed only in the basal epithelial layer and in a clustered manner. The oral epithelium showed dysplasia and a significant increase in the number of p75NTR- and PCNA-positive cells, which were localized mainly in the basal and suprabasal epithelial layers during weeks 5-16 of 4-NQO exposure. When the epithelium invaded the lamina propria and well-differentiated OSCC began, the p75NTR-positive cell frequency drastically decreased in epithelial cords and nests, showing a negative correlation with PCNA expression. p75NTR immunolabeling during 4-NQO-induced carcinogenesis was similar to that described for human head and neck dysplasia and neoplasia.

CONCLUSIONS

p75NTR immunolabeling observed in 4-NQO-induced oral dysplastic and OSCC lesions were related to the early phases of oral carcinogenesis and may help predict cell dysplasia and malignant transformation.

Generation and characterization of a human oral squamous carcinoma cell line SCC-9 with CRISPR/Cas9-mediated deletion of the p75 neurotrophin receptor

OBJECTIVE

To investigate the importance of the p75 neurotrophin receptor (p75^NTR) in human tongue squamous carcinoma cells, we exploited the CRISPR/Cas9 technology to establish a p75^NTR-knockout SCC-9 cell line and to explore the effect on biological functions.

MATERIALS AND METHODS

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated endonuclease (Cas9) system was used to generate genomic deletion mutants of p75^NTR in the tongue squamous carcinoma cell lines SCC-9. Single-guide RNA (sgRNA) sequences were designed to target the p75^NTR genomic sequence and were cloned into plasmid pGK1.1. The linearized vector was electroporated into SCC-9 cells and p75^NTR deletion was confirmed using Cruiser™ enzyme digestion and PCR amplification. SCC-9 clones with successful deletion of p75^NTR were identified and verified by sequencing and selected for functional testing in cell proliferation, invasion, migration, and colony-forming assays.

RESULTS

Compared with control cells, p75^NTR-knockout SCC-9 cells showed significantly diminished abilities to proliferate, invade, migrate, and form colonies, indicating a reduction in pro-tumorigenic behavior.

CONCLUSION

These data demonstrate, first, that the CRISPR/Cas9 system is a simplified method for generating p75^NTR knockouts with relatively high efficiency, and second, that deletion of p75^NTR suppresses several tumor-promoting properties of SCC-9 cells, suggesting that p75^NTR is a potential target for the development of novel therapies for tongue cancer.