Role of CD44 as a marker of cancer stem cells in head and neck cancer

Exploring stage‑specific embryonic antigen 3 involvement in oral cancer progression and as a potential target for taxane‑based chemotherapy

Despite significant advancements in therapeutic approaches, oral neoplasms remain formidable and life‑threatening conditions that affect a substantial number of individuals worldwide. Within oral malignancies, a subset of cancer stem cells (CSCs) represent a crucial population responsible for tumor initiation and progression. The identification of reliable markers for the detection and characterization of CSCs in solid tumors, particularly in the context of oral cancers, remains an ongoing challenge. Stage‑specific embryonic antigen 3 (SSEA3), previously associated with mesenchymal stem cells and linked to the progression of breast neoplasms and poor prognosis, has yet to be comprehensively elucidated in the context of oral malignancies. The present study aimed to investigate the expression and properties of SSEA3 in 16 distinct subsets of human oral neoplastic cell lines, classified as either CD44 positive (+) or CD44 negative (‑). For the first time, SSEA3 was examined as an indicator of tumorigenicity and resistance to taxane‑derived chemotherapeutic agents. In the majority of oral neoplastic cell lines analyzed, SSEA3 was expressed in a small population of CD44(+) cells. Significantly, SSEA3(+) cells exhibited heightened proliferative activity and upregulated expression of genes associated with stem cells compared with SSEA3(‑) cells. The aforementioned findings suggested that SSEA3 may contribute to the evolution and progression of oral malignancies by fostering tumor growth. Furthermore, SSEA3(+) cells displayed increased sensitivity to taxane‑based pharmaceuticals, indicating the potential for SSEA3 to be a viable target in the treatment schema for oral cavity neoplasms. In conclusion, the present study provides novel insight into the role of SSEA3 in the progression and management of oral neoplasms, potentially paving the way for more effective therapeutic approaches.

Do immunohistochemical studies have a role in predicting prognosis of laryngeal squamous cell carcinomas? CD44 and Fascin experience

BACKGROUND AND OBJECTIVES

The diagnosis of laryngeal squamous cell carcinoma (LSCC) can be made easily based on histopathological findings, but the relationship between morphological findings and prognosis is not clear. In addition to morphological findings, the use of novel markers may contribute to the development of new treatment strategies and improved patient prognosis. CD44, which is a cancer stem cell marker, and Fascin-1, an actin-binding protein has been associated with poor prognosis in many tumors. The aim of this study was to investigate the relationship between CD44 and Fascin-1 expression and clinicopathologic parameters in LSCC and their roles in the determination of clinical behavior and prognosis. The aim of this study is to investigate whether CD44 and Fascin have a relationship with clinicopathological parameters and have a role in determining clinical behavior and prognosis in LSCC.

METHODS

130 patients who were operated in our hospital for LSCC between 2012 and 2018 were included in this study. Fascin-1 and CD44 stains were applied immunohistochemically to the paraffin blocks of the tumors. Immunostained specimens were scored according to the intensity of staining and the percentage of staining for each marker. Overall scores were summed and was designated as immunoreactivity score (IRS). Finally, IRS was categorized into two groups; Low and High CD44/Fascin IRS.

RESULTS

There were no statistically significant differences between low and high CD44 and Fascin IRS groups in terms of clinicopathologic parameters, overall and disease-free survival (p> 0.05).

CONCLUSION

Immunhistochemical studies are not yet sufficient to predict patient prognosis. Morphological findings still remain of priority and importance for pathologists.

Comprehensive Molecular Landscape of Cetuximab Resistance in Head and Neck Cancer Cell Lines

Cetuximab is the sole anti-EGFR monoclonal antibody that is FDA approved to treat head and neck squamous cell carcinoma (HNSCC). However, no predictive biomarkers of cetuximab response are known for HNSCC. Herein, we address the molecular mechanisms underlying cetuximab resistance in an in vitro model. We established a cetuximab resistant model (FaDu), using increased cetuximab concentrations for more than eight months. The resistance and parental cells were evaluated for cell viability and functional assays. Protein expression was analyzed by Western blot and human cell surface panel by lyoplate. The mutational profile and copy number alterations (CNA) were analyzed using whole-exome sequencing (WES) and the NanoString platform. FaDu resistant clones exhibited at least two-fold higher IC50 compared to the parental cell line. WES showed relevant mutations in several cancer-related genes, and the comparative mRNA expression analysis showed 36 differentially expressed genes associated with EGFR tyrosine kinase inhibitors resistance, RAS, MAPK, and mTOR signaling. Importantly, we observed that overexpression of KRAS, RhoA, and CD44 was associated with cetuximab resistance. Protein analysis revealed EGFR phosphorylation inhibition and mTOR increase in resistant cells. Moreover, the resistant cell line demonstrated an aggressive phenotype with a significant increase in adhesion, the number of colonies, and migration rates. Overall, we identified several molecular alterations in the cetuximab resistant cell line that may constitute novel biomarkers of cetuximab response such as mTOR and RhoA overexpression. These findings indicate new strategies to overcome anti-EGFR resistance in HNSCC.

Current understanding of epigenetics mechanism as a novel target in reducing cancer stem cells resistance

At present, after extensive studies in the field of cancer, cancer stem cells (CSCs) have been proposed as a major factor in tumor initiation, progression, metastasis, and recurrence. CSCs are a subpopulation of bulk tumors, with stem cell-like properties and tumorigenic capabilities, having the abilities of self-renewal and differentiation, thereby being able to generate heterogeneous lineages of cancer cells and lead to resistance toward anti-tumor treatments. Highly resistant to conventional chemo- and radiotherapy, CSCs have heterogeneity and can migrate to different organs and metastasize. Recent studies have demonstrated that the population of CSCs and the progression of cancer are increased by the deregulation of different epigenetic pathways having effects on gene expression patterns and key pathways connected with cell proliferation and survival. Further, epigenetic modifications (DNA methylation, histone modifications, and RNA methylations) have been revealed to be key drivers in the formation and maintenance of CSCs. Hence, identifying CSCs and targeting epigenetic pathways therein can offer new insights into the treatment of cancer. In the present review, recent studies are addressed in terms of the characteristics of CSCs, the resistance thereof, and the factors influencing the development thereof, with an emphasis on different types of epigenetic changes in genes and main signaling pathways involved therein. Finally, targeted therapy for CSCs by epigenetic drugs is referred to, which is a new approach in overcoming resistance and recurrence of cancer.

Roles of microRNAs in Regulating Cancer Stemness in Head and Neck Cancers

Head and neck squamous cell carcinomas (HNSCCs) are epithelial malignancies with 5-year overall survival rates of approximately 40-50%. Emerging evidence indicates that a small population of cells in HNSCC patients, named cancer stem cells (CSCs), play vital roles in the processes of tumor initiation, progression, metastasis, immune evasion, chemo-/radioresistance, and recurrence. The acquisition of stem-like properties of cancer cells further provides cellular plasticity for stress adaptation and contributes to therapeutic resistance, resulting in a worse clinical outcome. Thus, targeting cancer stemness is fundamental for cancer treatment. MicroRNAs (miRNAs) are known to regulate stem cell features in the development and tissue regeneration through a miRNA-target interactive network. In HNSCCs, miRNAs act as tumor suppressors and/or oncogenes to modulate cancer stemness and therapeutic efficacy by regulating the CSC-specific tumor microenvironment (TME) and signaling pathways, such as epithelial-to-mesenchymal transition (EMT), Wnt/β-catenin signaling, and epidermal growth factor receptor (EGFR) or insulin-like growth factor 1 receptor (IGF1R) signaling pathways. Owing to a deeper understanding of disease-relevant miRNAs and advances in in vivo delivery systems, the administration of miRNA-based therapeutics is feasible and safe in humans, with encouraging efficacy results in early-phase clinical trials. In this review, we summarize the present findings to better understand the mechanical actions of miRNAs in maintaining CSCs and acquiring the stem-like features of cancer cells during HNSCC pathogenesis.

Green Salad Intake Is Associated with Improved Oral Cancer Survival and Lower Soluble CD44 Levels

Deficiencies in fruit and vegetable intake have been associated with oral cancer (oral cavity and oropharyngeal). Salivary rinses contain measurable biomarkers including soluble CD44 (solCD44) and total protein, which are known markers of oral cancer risk. This study investigates the effect of nutritional factors on solCD44 and protein levels to evaluate oral cancer risk and survival. We evaluated solCD44 and protein levels from 150 patients with oral and oropharyngeal squamous cell carcinoma and 150 frequency-matched controls. We subsequently characterized the effect of food group consumption and these biomarkers on progression-free survival (PFS) and overall survival (OS). Patients reported eating fewer servings of salad (p = 0.015), while controls reported eating fewer servings of potatoes (p < 0.001). Oral cancer patients who consumed at least one serving per week of green salad were found to have significantly lower CD44 levels than those who ate salad less frequently (mean of log₂[solCD44]1.73 versus 2.25, p = 0.014). Patients who consumed at least one serving per week of “salad or other vegetables” had significantly longer PFS (median 43.5 versus 9.1 months, p = 0.003, adjusted hazard ratio (HR) = 0.39 p = 0.014) and OS (median 83.6 versus 10 months, p = 0.008, adjusted HR = 0.04 p = 0.029). These findings suggest that dietary factors, namely greater green salad and vegetable intake, may be associated with lower CD44 levels and better prognosis in oral cancer patients.

Mitochondrial Stress-Mediated Targeting of Quiescent Cancer Stem Cells in Oral Squamous Cell Carcinoma

Introduction

Despite improved therapeutics in oral squamous cell carcinoma (OSCC), tumor cells that are either quiescent and/or endowed with stem cell–like attributes usually survive treatment and recreate tumor load at relapse. Through this study, we aimed strategically to eliminate these stem cell–like cancer cells using a combination drug approach.

Methods

Primary cultures from 15 well–moderately differentiated OSCC were established, and the existence of cancer cells with stem cell–like characteristics using five cancer stem cell (CSC) specific markers — CD44, CD133, CD147, C166, SOX2 and spheroid assay was ascertained. Next, we assessed quiescence in CSCs under normal and growth factor–deprived conditions using Ki67. Among several gene signatures regulating quiescent cellular state, we evaluated the effect of inhibiting Dyrk1b in combination with topoisomerase II and histone deacetylase inhibitors in targeting quiescent CSCs. Multiple drug-effect analysis was carried out with CompuSyn software to determine combination-index values.

Results

We observed that CD44⁺CD133⁺ showed the highest level of SOX2 expression. CSCs showed varying degrees of quiescence, and inhibition of Dyrk1b decreased quiescence and sensitized CSCs to apoptosis. In the drug-combination study, Dyrk1b inhibitor was combined with topoisomerase II and histone deacetylase inhibitors to target quiescent CSCs. In combination, a synergistic effect was seen even at a 16-fold lower dose than IC₅₀. Furthermore, combined treatment decreased glutathione levels and increased ROS and mitochondrial stress, leading to increased DNA damage and cytochrome c in CSCs.

Conclusion

We report marker-based identification of CSC subpopulations and synergy of Dyrk1b inhibitor with topoisomerase II and HDAC inhibitors in primary OSCC. The results provide a new therapeutic strategy to minimize quiescence and target oral CSCs simultaneously.

Enhanced Hyaluronan Signaling and Autophagy Dysfunction by VPS35 D620N

The motor features of Parkinson's disease (PD) result from the loss of dopaminergic (DA) neurons in the substantia nigra with autophagy dysfunction being closely linked to this disease. A PD-causing familial mutation in VPS35 (D620N) has been reported to inhibit autophagy. In order to identify signaling pathways responsible for this autophagy defect, we performed an unbiased screen using RNA sequencing (RNA-Seq) of wild-type or VPS35 D620N-expressing retinoic acid-differentiated SH-SY5Y cells. We report that VPS35 D620N-expressing cells exhibit transcriptome changes indicative of alterations in extracellular matrix (ECM)-receptor interaction as well as PI3K-AKT signaling, a pathway known to regulate autophagy. Hyaluronan (HA) is a major component of brain ECM and signals via the ECM receptors CD44, a top RNA-Seq hit, and HA-mediated motility receptor (HMMR) to the autophagy-regulating PI3K-AKT pathway. We find that high (>950 kDa), but not low (15-40 kDa), molecular weight HA treatment inhibits autophagy. In addition, VPS35 D620N facilitated enhanced HA-AKT signaling. Transcriptomic assessment and validation of protein levels identified the differential expression of CD44 and HMMR isoforms in VPS35 D620N mutant cells. We report that knockdown of HMMR or CD44 results in upregulated autophagy in cells expressing wild-type VPS35. However, only HMMR knockdown resulted in rescue of autophagy dysfunction by VPS35 D620N indicating a potential pathogenic role for this receptor and HA signaling in Parkinson's disease.

Comparison of Salivary and Serum Soluble CD44 Levels between Patients with Oral SCC and Healthy Controls

Background:

The most common type of oral cancer is oral squamous cell carcinoma. If it is diagnosed in the early stages; the success of the treatment can be increased. It seems that ELISA-based techniques as a screening tool for society are the most cost-effective methods for early diagnosis. CD44 is a key marker for the detection of SCC stem cells. The aim of this study was to compare the level of soluble CD44 in saliva and serum between patients with oral SCC and healthy controls.

Materials and Methods:

Saliva and serum were collected from 20 patients with primary OSCC and 20 healthy persons as control group. The samples were evaluated by an ELISA test kit. Data were analyzed by SPSS software version 22, chi-square, ANOVA, T-test and Spearman correlation test.

Results:

The mean of soluble CD44 level in serum and saliva of the patient and control groups are 531.51±228.95 and 453.3±113.74 (for serum) and 48.53±59.02 and 17.76±39.14 (for saliva) respectively. There was no statistically significant difference in serum and saliva solCD44 level between the patient and control groups (P value = 0.182 and P value = 0.061 respectively). Also, there was no significant correlation between the solCD44 level in each patient and control group in serum (P value = 0.61) and in saliva (P value = 0.445).

Conclusions:

Determination of solCD44 level in saliva and serum can be a useful method for diagnosis the person’s involvement with cancer cells and the cancer in the early stages. But according to the controversial outcomes of past studies, larger and more accurate studies are needed in groups with more cases of oral cancer.

Long non-coding RNA AFAP1-AS1/miR-320a/RBPJ axis regulates laryngeal carcinoma cell stemness and chemoresistance

AFAP1-AS1 is a long non-coding RNA that is associated with tumorigenesis and poor prognosis in a variety of cancers. We have been suggested that AFAP1-AS1 increases tumorigenesis in laryngeal carcinoma specifically by enhancing stemness and chemoresistance. We assessed AFAP1-AS1 expression in human laryngeal specimens, paired adjacent normal tissues and human HEp-2 cells. Indeed, we found not only that AFAP1-AS1 was up-regulated in laryngeal carcinoma specimens and cells, but also that stemness-associated genes were overexpressed. Silencing of AFAP1-AS1 promoted HEp-2 cell chemoresistance under cisplatin treatment. Expression of AFAP1-AS1 was increased in drug-resistant Hep-2 cells. We then probed the mechanism of AFAP1-AS1 activity and determined that miR-320a was a potential molecular target of AFAP1-AS1. Luciferase reporter and qRT-PCR assays of AFAP1-AS1 and miR-320a levels in human specimens and cell cultures indicated that AFAP1-AS1 negatively regulates miR-320a. To discover the molecular mechanism of miR-320a, we again used the DIANA Tools algorithm to predict its genetic target, RBPJ. After cloning the 3'-untranslated regions (3'-UTR) of RBPJ into a luciferase reporter, we determined that miR-320a did in fact reduce RBPJ mRNA and protein levels. Ultimately, we determined that AFAP1-AS1 increases RBPJ expression by negatively regulating miR-320a and RBPJ overexpression rescues stemness and chemoresistance inhibited by AFAP1-AS1 silencing. Taken together, these results suggest that AFAP1-AS1 can serve as a prognostic biomarker in laryngeal carcinoma and that miR-320a has the potential to improve standard therapeutic approaches to the disease, especially for cases in which cancer cell stemness and drug resistance present significant barriers to effective treatment.

[Coexpression of CD44 and Ki-67 in colon`s neoplast]

AIM

the evaluation of Ki-67 and CD44 expression in the 'serrated' polyps of the colon and comparison them with adenocarcinomas and tubular and tubule-villous adenomas of the colon.

MATERIAL AND METHODS

The study is including 49 'serrated' polyps, 34 tubular (AT) and tubulo-villous (ATV) adenomas and 32 adenocarcinomas of the colon. Antibodies CD44 and Ki-67 were used as immunohistochemical markers in this study.

RESULTS

A statistically significant difference (p<0.01) was observed between traditional serrated adenomas (TSA) from hyperplastic polyps (HP) and sessile serrated adenomas (SSA) in the Ki-67 level and the localization of the Ki-67 and CD44 reaction: surface areas of the crypts (upper third) in TSA and base of crypts (lower third) in HP and SSA. There was no difference between HP and SSA (p>0.05), neither by marker localization, nor by their level. In all 'serrated' polyps of the colon, the Ki-67 reaction was nuclear; CD44 - membrane (except for 1 TSA).

CONCLUSION

we are the first ones who suggested to evaluate not the overall level of reactions of CD44 and Ki-67, but particular level for each third part of crypts. The similarities of TSA, AT and ATV and between HP and SSA are shown as well as the principal statistical difference between these two groups. The cytoplasmic reaction of CD44 in adenocarcinomas and the membrane reaction of CD44 in 98% of the 'serrated' polyps of the colon are described. For the first time coexpression of CD44 and Ki-67 on particulate thirds of crypts in neoplasms of the colon is shown and the potential reasons for this phenomenon are discussed.

Inflammatory mediator ultra-low-molecular-weight hyaluronan triggers necrosis of B-precursor leukemia cells with high surface CD44 expression

Acute lymphoblastic leukemia (ALL) with mixed lineage leukemia (MLL) gene rearrangements (MLL+ALL) has a dismal prognosis and is characterized by high surface CD44 expression. Known that CD44 has the specific binding sites for a natural ligand hyaluronan (HA), we investigated biological effects of HA with different molecular sizes on MLL+ALL cell lines, and found that the addition of ultra-low-molecular-weight (ULMW)-HA strongly suppressed their thymidine uptakes. The MLL+ALL cell line lacking surface CD44 expression established by genome editing showed no suppression of thymidine uptake. Surface CD44-high B-precursor ALL cell lines other than MLL+, but not T-ALL cell lines, were also suppressed in their thymidine uptakes. The inhibition of thymidine uptakes was because of induction of cell death, but dead cells lacked features of apoptosis on cytospin smears and flow cytometric analysis. The cell death was neither blocked by pan-caspase inhibitor nor autophagy inhibitor, but was completely blocked by necrosis inhibitor necrostatin-1. Necrotic cell death was further supported by a marked release of a high-mobility protein group B1 and morphological changes on transmission electron microscopy. Elevation of intracellular reactive oxygen species production suggested a role for inducing this necrotic cell death. ULMW-HA-triggered cell death was similarly demonstrated in surface CD44-high primary B-precursor leukemia cells. Assuming that ULMW-HA is abundantly secreted at the site of infection and inflammation, this study sheds light on understanding the mechanism of a transient inflammation-associated remission of leukemia. Further, the CD44-targeting may become an effective approach in future for the treatment of refractory B-precursor ALL by its capability of predominantly eradicating CD44-high leukemia-initiating cells.

Cluster of Differentiation 44 (CD44) Gene Variants: A Putative Cancer Stem Cell Marker in Risk Prediction of Bladder Cancer in North Indian Population

CD44 is involved in cancer-cell growth, invasion, proliferation and metastasis and is also a causal factor for acquisition of resistance to apoptosis. Therefore we evaluated different SNPs of CD44 gene viz. CD44rs187116 A/G, CD44rs4755392 A/T, CD44rs187115 C/T, CD44rs13347 C/T and CD44 rs353639 G/T for bladder cancer risk in North Indian population. 240 bladder cancer patients and 270 cancer free controls were recruited in this study. Genotyping was done by PCR-RFLP for CD44rs187116 A/G. However, CD44rs4755392 A/T, CD44rs187115 C/T, CD44rs13347 C/T and CD44 rs353639 G/T were genotyped by allelic discrimination Taqman^® assay. Statistical analysis was done by SPSS. In-silico analysis was done using F-SNP. We found reduced risk in variant genotype, TT of rs4755392 (p = 0.011) as well as in variant allele, T (p = 0.045). No risk was seen in rs13347, heterozygous genotype, CT (p = 0.023) and variant allele, T (p = 0.007). The dominant model, CT + TT also revealed reduced risk (p = 0.009). A marginal risk was seen in dominant model, GT + TT of rs353639 (p = 0.044) and reduced risk in variant allele T (p = 0.040). A significant manifold risk was seen in smokers carrying variant genotype, TT of CD44rs353639 G/T (p = 0.038, OR 1.960). Haplotypic analysis revealed significant association in 4 sets viz. TCCGG p = 0.005, TTCGA p = 0.039, ACTGG p = 0.008 and TCTGA p = 0.006. In-silico analysis using F-SNP, showed altered transcriptional regulation for rs187115, rs13347 and rs353639. Our study suggests that rs353639 shows a marginal risk for bladder cancer susceptibility, whereas rs4755392 and rs13347 have reduced risk of bladder cancer and rs187115 and rs187116 had no effect on bladder cancer susceptibility in North Indians.

Connexin 43 (Cx43) Expression in Laryngeal Squamous Cell Carcinomas: Preliminary Data on Its Possible Prognostic Role

The aim of the report is to evaluate the prognostic and predictive role of Connexin 43 (Cx43) expression in laryngeal squamous cell carcinomas. Eighty-seven previously untreated patients submitted to laryngectomy ± neck dissection ± radiotherapy were enrolled in this retrospective study. The original primary tumor slides were reassessed, tumor grade and stage reviewed, and Cx43 immunohistochemical analysis performed: only cytoplasmic membranous staining of Cx43 has been shown. Neither significant correlation has been showed for clinical T (p = 0.75) and N (p = 0.81), while significant correlation has been found with grading (p < 0.0001) and pathological N (p < 0.0001). Five year overall survival (OS) of the 87 patients was 54 %; 5 year OS was 59.6 % in Cx43 positive patients and 37.1 % in Cx43 negative patients, but also this difference did not reach statistical significance (p = 0.058). Our best findings were: poorly differentiated carcinomas had low or negative Cx43 expression; moderately differentiated tumors without node metastasis and no radiotherapy but with Cx43 expression had a better outcome; moderately differentiated tumors without node metastasis and no radiotherapy but without Cx43 expression had a worse outcome; moderately differentiated tumors with node metastasis and radiotherapy but without Cx43 expression had a better outcome. Interestingly, in G2 head and neck squamous cell carcinomas with lymph node metastasis at the time of diagnosis, Cx43 aberrant overexpression could identify a subset of patients with poor prognosis, far less responsive to radio/chemotherapy.

Cancer Stem Cell Signaling during Repopulation in Head and Neck Cancer

The aim of the study was to investigate cancer stem signaling during the repopulation response of a head and neck squamous cell cancer (HNSCC) xenograft after radiation treatment. Xenografts were generated from low passage HNSCC cells and were treated with either sham radiation or 15 Gy in one fraction. At different time points, days 0, 3, and 10 for controls and days 4, 7, 12, and 21, after irradiation, 3 tumors per group were harvested for global gene expression, pathway analysis, and immunohistochemical evaluation. 316 genes were identified that were associated with a series of stem cell-related genes and were differentially expressed (p ≤ 0.01 and 1.5-fold) at a minimum of one time point in UT-SCC-14 xenografts after radiation. The largest network of genes that showed significant changes after irradiation was associated with CD44, NOTCH1, and MET. c-MET and ALDH1A3 staining correlated with the changes in gene expression. A clear pattern emerged that was consistent with the growth inhibition data in that genes associated with stem cell pathways were most active at day 7 and day 12 after irradiation. The MET/CD44 axis seemed to be an important component of the repopulation response.

Cancer stem-like cell: a novel target for nasopharyngeal carcinoma therapy

Nasopharyngeal carcinoma (NPC) is the most common cancer originating in the nasopharynx, and is extremely common in southern regions of China. Although the standard combination of radiotherapy and chemotherapy has improved the efficiency in patients with NPC, relapse and early metastasis are still the common causes of mortality. Cancer stem-like cells (CSCs) or tumor initial cells are hypothesized to be involved in cancer metastasis and recurrence. Over the past decade, increasing numbers of studies have been carried out to identify CSCs from human NPC cells and tissues. The present paper will summarize the investigations on nasopharyngeal CSCs, including isolation, characteristics, and therapeutic approaches. Although there are still numerous challenges to translate basic research into clinical applications, understanding the molecular details of CSCs is essential for developing effective strategies to prevent the recurrence and metastasis of NPC.

Targeting head and neck cancer stem cells to overcome resistance to photon and carbon ion radiation

Although promising new radiation therapy techniques such as hadrontherapy are currently being evaluated in the treatment of head and neck malignancies, local control of head and neck squamous cell carcinoma (HNSCC) remains low. Here, we investigated the involvement of cancer stem-like cells (CSCs) in a radioresistant HNSCC cell line (SQ20B). Stem-like cells SQ20B/SidePopulation(SP)/CD44(+)/ALDH(high) were more resistant to both photon and carbon ion irradiation compared with non-CSCs. This was confirmed by a BrdU labeling experiment, which suggests that CSCs were able to proliferate and to induce tumorigenicity after irradiation. SQ20B/SP/CD44(+)/ALDH(high) were capable of an extended G2/M arrest phase in response to photon or carbon ion irradiation compared with non-CSCs. Moreover, our data strongly suggest that resistance of CSCs may result from an imbalance between exacerbated self-renewal and proliferative capacities and the decrease in apoptotic cell death triggering. In order to modulate these processes, two targeted pharmacological strategies were tested. Firstly, UCN-01, a checkpoint kinase (Chk1) inhibitor, induced the relapse of G2/M arrest and radiosensitization of SQ20B-CSCs. Secondly, all-trans retinoic acid (ATRA) resulted in an inhibition of ALDH activity, and induction of the differentiation and radiosensitization of SQ20B/SP/CD44(+)/ALDH(high) cells. The combination of ATRA and UCN-01 treatments with irradiation drastically decreased the surviving fraction at 2Gy of SQ20B-CSCs from 0.85 to 0.38 after photon irradiation, and from 0.45 to 0.21 in response to carbon ions. Taken together, our results suggest that the combination of UCN-01 and ATRA represent a promising pharmacological-targeted strategy that significantly sensitizes CSCs to photon or carbon ion radiation.

Significance of CD44 expression in head and neck cancer: a systemic review and meta-analysis

BACKGROUND

CD44 has been reported to be involved with tumor growth and metastasis and has also been implicated as a CSC marker in head and neck squamous cell cancer (HNSCC). However, the prognostic value of CD44 still remains controversial; hence, we investigated the correlation between CD44 and the clinicopathological features of HNSCC by meta-analysis.

METHODS

A comprehensive search was performed using PubMed, ISI web of Science and China National Knowledge Infrastructure (CNKI) up to April 2013. Only studies with immunohistochemical staining of HNSCC were considered. Data on TNM classification, tumor grade, disease free survival and 3- or 5-year overall survival rate were extracted.

RESULTS

Thirty studies with 2102 patients met the inclusion criteria for the meta-analysis. Fifteen studies used anti-pan-CD44 antibody, 9 used anti-CD44-v6 antibody, 2 used anti-CD44-v3 and 2 used anti-CD44s antibody, 1 used anti-CD44-v9, and 1 used anti-CD44-v6,-v3 and -v4-5 simultaneously. The total percentage of CD44 expression was 57.8%, with 49.3% in oral cancer patients, 66.4% in pharynx and 54.7% in larynx cancer patients expressing CD44. No significant correlation between clinical features and CD44 expression was revealed for oral cancer patients, but CD44 was shown to be associated with advanced T categories (larynx: RR = 1.33, 95% CI 1.01-1.76; larynx & pharynx RR = 1.21, 95% CI 1.08-1.35), worse N categories (larynx: RR = 2.53, 95% CI 1.99-3.21; larynx & pharynx RR = 1.95, 95% CI 1.35-2.82), higher tumor grades (larynx & pharynx RR = 1.71, 95% CI 1.04-2.79) and 5-year OS rates (larynx: RR = 0.62, 95% CI 0.47-0.83; larynx & pharynx RR = 0.66, 95% CI 0.47-0.94) in patients with laryngeal and pharyngolaryngeal cancer. In stratified analysis, pan-CD44 and CD44-v6 expression were both correlated with 5-year OS rate of patients with laryngeal (CD44: RR = 0.66, 95% CI 0.46-0.95; CD44-v6 RR = 0.53, 95% CI 0.37-0.77) and pharyngolaryngeal cancer (CD44: RR = 0.56, 95% CI 0.34-0.93; CD44-v6 RR = 0.53, 95% CI 0.37-0.77).

CONCLUSIONS

Our analysis suggested that CD44 is related to worse T category, N category, tumor grade and prognosis, in pharyngeal and laryngeal cancer, but no clear association was revealed between CD44 expression and oral cancer.

CD44 targets Wnt/β-catenin pathway to mediate the proliferation of K562 cells

Background

Chronic myeloid leukemia is a clonal myeloproliferative disorder disease in which BCR/ABL plays an important role as an oncoprotein and molecular target. Despite the success of targeted therapy using tyrosine kinase inhibitors, CML remains largely incurable, most likely due to the treatment resistance after firstly chemical therapy. So know well the unique molecular pathway of CML is very important.

Methods

The expressions of CD44 in different leukemia patients and cell lines were detected by real-time PCR and western blotting. The effects of CD44 on proliferation of K562 cells were determined using the MTT and colony formation assays, and even in a nude mouse transplantation model. Then, the cell cycle changes were detected by flow cytometric analysis and the early apoptosis of cells was detected by the annexin V/propidium iodide double-staining assay. The expressions of the cycles and apoptosis-related proteins p21, Cyclin D1 and Bcl-2 were analyzed by western blot and real-time PCR assay. Finally, the decreased nuclear accumulation of β-catenin was detected by western blotting and immunefluorescence.

Results

Firstly, we showed that CD44 expression was increased in several kinds of leukemia patients and K562 cells. By contrast, the down-regulation of CD44 resulted in decreased proliferation with a G₀/G₁ arrest of cell cycle in K562 cells according to the MTT assay and the flow cytometric analysis. And no significant induction of both the early and late phases of apoptosis was shown by the annexin V-FITC and PI staining. During this process, p21 and cyclin D1 are the major causes for cell cycle arrest. In addition, we found CD44 down-regulation decreased the expression of β-catenin and increased the expression of phosphorylated β-catenin. The instability of Wnt/β-catenin pathway induced by increased expression of p-β-catenin resulted in a decreased nuclear accumulation in CD44 silenced K562 cells. In the nude mouse transplantation model, we also found the same results.

Conclusions

These results show that K562 cells depend to a greater extent on CD44 for proliferation, and CD44 down-regulation may induce a cell cycle arrest through Wnt/β-catenin pathway. CD44 blockade may be beneficial in therapy of CML.

Cancer stem cells in head and neck cancer

Cancer stem cells (CSCs), also called “cells that start the tumor,” represent in themselves one of the most topical and controversial issues in the field of cancer research. Tumor stem cells are able to self-propagate in vitro (self-renewal), giving rise both to other tumor stem cells and most advanced cells in the line of differentiation (asymmetric division). A final characteristic is tumorigenicity, a fundamental property, which outlines the tumor stem cell as the only cell able to initiate the formation of a tumor when implanted in immune-deficient mice. The hypothesis of a hierarchical organization of tumor cells dates back more than 40 years, but only in 1997, thanks to the work of John Dick and Dominique Bonnet, was there the formal proof of such an organization in acute myeloid leukemia. Following this, many other research groups were able to isolate CSCs, by appropriate selection markers, in various malignancies, such as breast, brain, colon, pancreas, and liver cancers and in melanoma. To date, however, it is not possible to isolate stem cells from all types of neoplasia, particularly in solid tumors. From a therapeutic point of view, the concept of tumor stem cells implies a complete revision of conventional antineoplastic treatment. Conventional cytotoxic agents are designed to target actively proliferating cells. In the majority of cases, this is not sufficient to eliminate the CSCs, which thanks to their reduced proliferative activity and/or the presence of proteins capable of extruding chemotherapeutics from the cell are not targeted. Therefore, the theory of cancer stem cells can pose new paradigms in terms of cancer treatment. Potential approaches, even in the very early experimental stages, relate to the selective inhibition of pathways connected with self-renewal, or more specifically based on the presence of specific surface markers for selective cytotoxic agent vehicles. Finally, some research groups are trying to induce these cells to differentiate, thus making them easier to remove. For all these reasons, we have collected existing literature on head and neck cancer stem cells that correlate the biological characteristics of this subpopulation of cancer cells with the clinical behavior of tumors.