Clinical Significance of Cancer Stem Cell Markers in Primary and Metastatic Tissues in Patients With Breast Cancer

BACKGROUND/AIM

This study aimed to examine the clinical significance of the protein expression of the cancer stem cell (CSC) markers ALDH1A1, CD133, CD44, and MSI-1 in primary and metastatic tissues of patients with breast cancer (BC).

PATIENTS AND METHODS

ALDH1A1, CD133, CD44, and MSI-1 protein expression in pairs of primary and metastatic tissues of 55 patients with BC with metastases treated at Kanagawa Cancer Center between January 1970 and December 2016 were evaluated using immunohistochemical assay and their association with clinicopathological factors and survival was examined.

RESULTS

There were no significant differences in CSC marker expression rates between primary and metastatic tissues for any CSC markers. Regarding the relationship between CSC marker expression in primary tissues and survival, patients with high CD133 expression had significantly lower recurrence-free survival (DFS) and overall survival. On multivariate analysis, they were also a poor independent predictor of DFS (hazard ratio=4.993, 95%CI=2.189-11.394, p=0.0001). In contrast, there was no significant association between the expression of any CSC marker in metastatic tissues and survival.

CONCLUSION

CD133 expression in the primary BC tissue may be a useful risk factor for recurrence in patients with BC.

1,2,3,4,6-Penta-O-galloyl-β-D-glucose Inhibits CD44v3, a cancer stem cell marker, by regulating its transcription factor, in human pancreatic cancer cell line

Inhibition of cluster of differentiation 44 (CD44), a pancreatic cancer stem cell (CSC) marker, is a potential treatment for pancreatic ductal adenocarcinoma (PDAC). In this study, we evaluated the effect of 1,2,3,4,6-penta-O-galloyl-β-D-glucose (PGG), a gallotannin contained in various medicinal plants, on CD44 standard (CD44s) and CD44 variant 3 (CD44v3) in Mia-PaCa-2, human pancreatic cancer cells and explored the underlying mechanisms. PGG showed cytotoxic effects and inhibited the proliferation of Mia-PaCa-2 cells. It also inhibited clonogenic activity, adhesion to fibronectin, and cell migration, which are characteristics of CSCs. PGG inhibited the expression of CD44s and CD44v3 by inducing the phosphorylation of p53 and suppressing NF-κB and Foxo3. Inhibition of Foxo3 induces CD44v3 ubiquitination. Indeed, PGG increased proteasome activity and promoted CD44v3 ubiquitination. PGG downregulated the CSC regulatory factors Nanog, Oct-4, and Sox-2, which act downstream of CD44v3 signaling. These data indicate that PGG may have therapeutic effects in pancreatic cancer mediated by inhibition of CSC markers.

Research Progress of DCLK1 Inhibitors as Cancer Therapeutics

Doublecortin-like kinase 1 (DCLK1) has emerged over the last decade as a unique stem cell marker within gastrointestinal tissues. Evidence from mouse models shows that high Dclk1 expression denotes a population of cells that promote tissue regeneration and serve as potential cancer stem cells. Moreover, since specific DCLK1 isoforms are overexpressed in many cancers and not normal cells, targeting the expression or kinase activity of DCLK1 can inhibit cancer cell growth. Here we review the evidence for DCLK1 as a prospective cancer target, including its isoform-specific expression and mutational status in human cancers. We further discuss the challenges and current progress in the development of small-molecule inhibitors of DCLK1.

CD44 expression enhances chemoresistance and implies occult micrometastases after conversion hepatectomy for initially unresectable colorectal liver metastases

AIM

The objective of this study was to examine the clinical and biological significance of CD44 expression in conversion hepatectomy for initially unresectable colorectal liver metastases.

METHODS

Fifty-four patients who received chemotherapy followed by hepatectomy (conversion hepatectomy) for initially unresectable liver metastases were enrolled. CD44 expression and its clinical significance were examined in 52 resected specimens; two specimens revealed no residual cancer cells. The biological significance of CD44 expression in the chemoresistance response to fluorouracil, oxaliplatin or irinotecan, three major anti-cancer agents for colon cancer in the clinical setting, was examined using colon cancer cell lines.

RESULTS

Membrane CD44 expression in the residual cancer cells after chemotherapy for colorectal liver metastases was detectable in 19 patients (37%), and was significantly associated with high proliferative activity represented by Ki-67 expression (P = 0.003). CD44 expression was also significantly associated with shorter disease-free survival and worse overall survival after hepatectomy (hazard ratio and P-values were 2.570, 0.007 and 3.457, 0.026, respectively). In SW480 and HT29 colon cancer cells, siRNA-mediated CD44 knockdown attenuated cell growth. Additionally, CD44 knockdown overcame chemoresistance in response to fluorouracil and oxaliplatin with enhanced apoptosis and p27 upregulation, respectively. For irinotecan, CD44 knockdown showed no additional effect in chemoresistance.

CONCLUSIONS

CD44 enhances chemoresistance in response to anti-cancer drugs (fluorouracil and oxaliplatin) in colon cancer cells. CD44 expression in liver metastases after chemotherapy implies the presence of occult micrometastases and is a worse prognostic factor in patients with conversion hepatectomy for initially unresectable colorectal liver metastases.

Clinicopathologic and prognostic significance of LGR5, a cancer stem cell marker in patients with colorectal cancer

Aim:

To analyze the clinicopathologic and prognostic significance of Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5), a cancer stem cell marker expression in a cohort of colorectal cancer patients (CRC).

Patients & methods:

A total of 76 formalin-fixed paraffin-embedded tissue blocks of primary or metastatic tumors from 49 CRC patients were collected for duration 2009–2015. LGR5 expression was assessed through immunohistochemical staining of a tissue microarray.

Results:

LGR5 was significantly over expressed in CRC tissue samples and found to be a statistically significant independent prognostic marker for an improved overall survival.

Conclusion:

LGR5 expression was higher in colorectal cancer than in normal tissue. LGR5 was an independent prognostic marker for better clinical outcomes and might be used as a potential therapeutic target in CRCs.

Augmented CD133 expression in distal margin correlates with poor prognosis in colorectal cancer

Pathological assessment of excised tumour and surgical margins in colorectal cancer (CRC) play crucial role in prognosis after surgery. Molecular assessment of margins could be more sensitive and informative than conventional histopathological analysis. Considering this view, we evaluated the distal surgical margins for expression of cancer stem cell (CSC) markers. Cellular and molecular assessment of normal, tumour and distal margin tissues were performed by flow cytometry, real-time q-PCR and immuno-histochemical analysis for CRC patients after tumour excision. CRC patients were evaluated for expression of CSC markers in their normal, tumour and distal tissues. Flow cytometry assay revealed CD133 and CD44 enriched cells in distal margin and tumour compared to normal colorectal tissues, which was further confirmed by immunohistochemistry. Most importantly, immunohistochemistry also revealed the enrichment of CSC markers expression in pathologically negative distal margins. Patients with distal margin enriched for CD133 expression showed an increased recurrence rate and decreased disease-free survival. This study proposes that although distal margin seems to be tumour free in conventional histopathological analysis, it could harbour cells enriched for CSC markers. Further CD133 could be a promising molecule to be used in molecular pathology for disease prognosis after surgery in CRC patients.

Cytoplasmic CD133 expression correlates with histologic differentiation and is a significant prognostic factor in extrahepatic bile duct cancer and gallbladder cancer

Prominin-1 (CD133) is one of the most important stem cell markers among various malignant tumor types, but the clinicopathological significance of CD133 expression in intrahepatic cholangiocarcinoma remains controversial. To the best of our knowledge, there have been no reports on extrahepatic bile duct cancer (EHBDCA) and gallbladder cancer (GBCA). The present study examined the clinicopathological significance of CD133 expression in EHBDCA and GBCA. Immunohistochemistry was used to evaluate CD133 expression in resected specimens obtained from 82 patients with EHBDCA and GBCA, and this expression was compared with the clinicopathological parameters and survival data of the patients. Cytoplasmic CD133 expression was identified in 20 patients, and its incidence was significantly associated with histopathological grade (P=0.035), pT factor (P=0.020) and recurrence (P=0.046). Survival analysis revealed that cytoplasmic CD133 expression in patients was significantly associated with a poorer overall survival (OS) and relapse-free survival (RFS) compared with those without cytoplasmic expression (5-year OS rate, 11.6% vs. 39.1%; 3-year RFS rate, 12.5% vs. 42.0%, respectively). Multivariate analysis revealed that cytoplasmic CD133 expression was an independent prognostic factor for OS and RFS (P=0.0036 and P<0.0001, respectively). To the best of our knowledge, this is the first report demonstrating that cytoplasmic CD133 expression was associated with histologic differentiation, cancer progression, recurrence and poor prognosis in EHBDCA and GBCA. CD133 expression may be a useful marker for clinical prognosis in patients with EHBDCA and GBCA.

Prognostic significance of stem cell-related marker expression and its correlation with histologic subtypes in lung adenocarcinoma

Cancer stem cells (CSCs) are a small subset of tumor cells that exhibit stem cell-like properties and contribute in treatment failure. To clarify the expression and prognostic significance of several CSC markers in non-small cell lung cancer, we retrospectively analyzed 368 patients with adenocarcinoma (n = 226) or squamous cell carcinoma (n = 142). We correlated the expression of six CSC markers – CD133, CD44, aldehyde dehydrogenase 1 (ALDH1), sex determining region Y-box 2 (SOX2), octamer binding transcription factor 4 (OCT4), and Nanog – with clinicopathologic and molecular variables and survival outcomes. In adenocarcinoma, CD133, ALDH1 and CD44 expression was associated with low pathologic stage and absence of lymphovascular invasion, while Nanog expression correlated with high histologic grade, lymphatic invasion and increased expression of Snail-1, a transcription factor associated with epithelial-mesenchymal transition. CSC marker expression was also associated with histologic subtypes in adenocarcinoma. Multivariate analysis showed that high Nanog expression was an independent factor associated with a poor prognosis in adenocarcinoma. CSC markers had no prognostic value in squamous cell carcinoma. These results suggest that Nanog is an independent negative prognostic factor that may be associated with epithelial-mesenchymal transition in lung adenocarcinoma.

Cancer stem cell targeted therapy: progress amid controversies

Although cancer stem cells have been well characterized in numerous malignancies, the fundamental characteristics of this group of cells, however, have been challenged by some recent observations: cancer stem cells may not necessary to be rare within tumors; cancer stem cells and non-cancer stem cells may undergo reversible phenotypic changes; and the cancer stem cells phenotype can vary substantially between patients. Here the current status and progresses of cancer stem cells theory is illustrated and via providing a panoramic view of cancer therapy, we addressed the recent controversies regarding the feasibility of cancer stem cells targeted anti-cancer therapy.

Therapeutics targeting CD90-integrin-AMPK-CD133 signal axis in liver cancer

CD90 is used as a marker for cancer stem cell in liver cancer. We aimed to study the mechanism by which CD90 promoted liver cancer progression and identify the new therapeutic targets on CD90 signal pathway. Ectopic expression of CD90 in liver cancer cell lines enhanced anchorage-independent growth and tumor progression. Furthermore, CD90 promoted sphere formation in vitro and upregulated the expression of the cancer stem cell marker CD133. The CD133 expression was higher in CD45-CD90+ cells in liver cancer specimen. The natural carcinogenic molecules TGF-β-1, HGF, and hepatitis B surface antigen increased the expression of CD90 and CD133. Inhibition of CD90 by either shRNA or antibody attenuated the induction of CD133 and anchorage-independent growth. Lentiviral delivery of CD133 shRNA abolished the tumorigenicity induced by CD90. Ectopic expression of CD90 induced mTOR phosphorylation and AMPK dephosphorylation. Mutation of integrin binding-RLD domain in CD90 attenuated the induction of CD133 and anchorage-independent growth. Similar results were observed after silencing β3 integrin. Signaling analyses revealed that AMPK/mTOR and β3 integrin were required for the induction of CD133 and tumor formation by CD90. Importantly, the energy restriction mimetic agent OSU-CG5 reduced the CD90 population in fresh liver tumor sample and repressed the tumor growth. In contrast, sorafenib did not decrease the CD90+ population. In conclusion, the signal axis of CD90-integrin-mTOR/AMPK-CD133 is critical for promoting liver carcinogenesis. Molecules inhibiting the signal axis, including OSU-CG5 and other inhibitors, may serve as potential novel cancer therapeutic targets in liver cancer.

ALDH1A1-overexpressing cells are differentiated cells but not cancer stem or progenitor cells in human hepatocellular carcinoma

Aldehyde dehydrogenase 1A1 (ALDH1A1) is considered to be a cancer stem cell marker in several human malignancies. However, the role of ALDH1A1 in hepatocellular carcinoma (HCC) has not been well elucidated. In this study, we investigated the relationship between ALDH1A1 and clinicopathological findings and examined whether ALDH1A1 deserves to be a cancer stem cell marker in HCC. Sixty HCC samples obtained from surgical resection were collected for immunohistochemical (IHC) staining. Of these 60 samples, 47 samples of HCC tumorous and non-tumorous tissues were evaluated with qRT-PCR. There was no significant difference in the ALDH1A1-mRNA level between tumorous and non-tumorous tissues. Tumorous ALDH1A1-mRNA level had no relationship with the clinicopathological features. Immunoreactivity of ALDH1A1 was classified into two groups based on the percentage of ALDH1A1-overexpressing cells. The ALDH1A1-high group was significantly associated with low serum levels of α-fetoprotein, small tumor diameter, very little lymphovascular invasion, more differentiated pathology and good stage. The ALDH1A1-high group showed more favorable prognosis for recurrence-free survival. In double-staining IHC, ALDH1A1 was not co-expressed with BMI1, EpCAM, CD13, CD24, CD90 and CD133, which reported as cancer stem cell markers in HCC. In conclusion, ALDH1A1-overexpressing cells could appear to be differentiated cells rather than cancer stem cells in HCC.

CD24 negative lung cancer cells, possessing partial cancer stem cell properties, cannot be considered as cancer stem cells

Cancer stem cells (CSCs) play vital role in lung cancer progression, resistance, metastasis and relapse. Identifying lung CSCs makers for lung CSCs targeting researches are critical for lung cancer therapy. In this study, utilizing previous identified lung CSCs as model, we compared the expression of CD24, CD133 and CD44 between CSCs and non-stem cancer cells. Increased ratio of CD24- cells were found in CSCs. CD24- cells were then sorted by flow cytometry and their proliferative ability, chemo-resistance property and in vivo tumor formation abilities were detected. A549 CD24- cells formed smaller colonies, slower proliferated in comparison to A549 CD24+ cells. Besides, A549 CD24- exhibited stronger resistance to chemotherapy drug. However, A549 CD24- didn't exert any stronger tumor formation ability in vivo, which is the gold standard of CSCs. These results showed that CD24- A549 cells showed some properties of CSCs but not actually CSCs. This study provides evidence that CD24 cannot be considered as lung CSCs marker.

Co-expression of Cytoskeletal Protein Adducin 3 and CD133 in Neurospheres and a Temozolomide-resistant Subclone of Glioblastoma

BACKGROUND

Glioma stem cells are associated for temozolomide-resistance in glioblastoma. Adducin 3 (ADD3) is a cytoskeletal protein associated with chemoresistance but its role in glioblastoma has not been investigated.

MATERIALS AND METHODS

Using an in vitro model of glioblastoma cells with acquired temozolomide resistance (D54-MG-R), the expressions of ADD3 and cancer stem cell markers were compared to those in temozolomide-sensitive glioblastoma cells (D54-MG-S). Immunofluorescence staining was used to investigate the expression patterns of ADD3 and cancer stem cell markers in temozolomide resistance and neurospheres of glioblastoma.

RESULTS

Chemoresistant cells were found to have up-regulation of ADD3 and CD133 expression. A sub-population of D54-MG-R cells and glioma neurospheres exhibited coexpression of ADD3 with CD133.

CONCLUSION

To our knowledge, this is the first report of a possible link between cytoskeletal protein expression, cancer stem cell phenotype and temozolomide resistance in human glioblastoma. This report lays the foundation for further investigation for ADD3 as a potential biomarker and therapeutic target in temozolomide-resistant glioma cells.

Comparative characterization of stem cell marker expression, metabolic activity and resistance to doxorubicin in adherent and spheroid cells derived from the canine prostate adenocarcinoma cell line CT1258

BACKGROUND

Canine prostate cancer represents a spontaneous animal model for the human counterpart. Cells with stem cell-like character are considered to play a major role in therapeutic resistance and tumor relapse. Thus, the identification of markers allowing for recognition and characterization of these cells is essential.

MATERIALS AND METHODS

Expression of 12 stem cell marker genes in the canine prostate cancer cell line CT1258 and spheroid cells generated from these was analyzed by quantitative real-time PCR. In CT1258 and the generated spheroid cells, CD44 and CD133 expression was analyzed by flow cytometry, as well as proliferation and doxorubicin resistance.

RESULTS

Integrin alpha-6 (ITGA6) expression and metabolic activity were significantly up-regulated in CT1258-derived spheroid cells, while doxorubicin resistance remained comparable.

CONCLUSION

ITGA6 de-regulation and metabolic activity appear to be characteristic of the generated spheres, indicating potential intervention targets.

Aldehyde dehydrogenase-1 predicts favorable prognosis in patients with vulvar squamous cell carcinoma

BACKGROUNDS

Aldehyde dehydrogenase-1 (ALDH1) has been considered as a potential cancer stem cell marker in different types of cancer. In the present study, we investigated the expression of ALDH1 in vulvar squamous cell carcinoma, and evaluated its correlation with clinicopathological factors in patients suffering from this disease.

MATERIALS AND METHODS

One hundred and fifty-four patients with vulvar squamous cell carcinoma, together with their verified histopathological and complete clinical data in Norway were included in the study. All paraffin-embedded samples of the primary vulvar carcinoma were recruited. The presence of ALDH1 was detected by immunohistochemistry and compared against commonly recognized prognostic factors.

RESULTS

By immunohistochemical staining, the expression of ALDH1 was observed in 10/154 (6.5%) vulvar squamous cell carcinomas, while being extensively expressed in the suprabasal cells in normal vulvar epithelia from patients with benign gynecological disease and non-malignant epithelia adjacent to the tumor cells. In addition, ALDH1 was highly expressed in stromal fibroblasts, blood vessels and keratinized pearl of the carcinoma in all the samples. Patients with ALDH1-positive tumors had a significantly longer disease-specific survival (p=0.042).

CONCLUSION

Contrary to the characteristics of cancer stem cells shown in other types of cancer with positive expression of ALDH1, the positive expression of ALDH1 in patients with vulvar squamous cell carcinoma indicates a significantly better prognosis. Furthermore, there is a trend that the expression of ALDH1 is associated with better histological differentiation.

Cancer stem cell-related marker expression in lung adenocarcinoma and relevance of histologic subtypes based on IASLC/ATS/ERS classification

Background

The cancer stem cell (CSC) theory has been proposed to explain tumor heterogeneity and the carcinogenesis of solid tumors. The aim of this study was to clarify the clinical role of CSC-related markers in patients with lung adenocarcinoma and to determine whether each CSC-related marker expression correlates with the histologic subtyping proposed by the International Association for the Study of Lung Cancer (IASLC), the American Thoracic Society (ATS), and the European Respiratory Society (ERS) classifications.

Methods

We reviewed data for all 103 patients in whom complete resection of adenocarcinoma had been performed. Expression of CSC-related markers, ie, aldehyde dehydrogenase 1A1 (ALDH1A1), aldo-keto reductase 1C family member 1 (AK1C1), and 1C family member 3 (AK1C3), was examined using immunostaining on whole-mount tissue slides, and the tumors were reclassified according to the IASLC/ATS/ERS classification.

Results

ALDH1A1 expression was observed in 66.0% of tumors, AK1C1 in 62.7%, and AK1C3 in 86.1%. Immunoreactivities with the frequency of mean expression of ALDH1A1 in papillary predominant adenocarcinoma were significantly higher than those of solid predominant adenocarcinoma (P<0.05). Papillary predominant adenocarcinoma had significantly lower expression of AK1C1 when compared with noninvasive or solid predominant adenocarcinomas (P<0.05). On multivariate analysis, larger tumor size (hazards ratio 1.899, P=0.044), lymph node metastasis (hazards ratio 2.702, P=0.005), and low expression of ALDH1A1 (hazards ratio 3.218, P<0.001) were shown to be independently associated with an unfavorable prognosis.

Conclusion

Immunohistochemistry of ALDH1A1 expression is strongly associated with prognosis. Expression of each CSC-related marker varies according to subtype, suggesting that a comprehensive histologic subtyping approach in the IASLC/ATS/ERS classification provides new molecular biology insights into the genesis of lung adenocarcinoma according to CSC theory.

Identification of the putative intestinal stem cell marker doublecortin and CaM kinase-like-1 in Barrett's esophagus and esophageal adenocarcinoma

BACKGROUND AND AIM

In Barrett's esophagus (BE), the normal esophageal squamous epithelium is replaced with a specialized metaplastic columnar epithelium. BE is a premalignant lesion that can progress to esophageal adenocarcinoma (EAC). Currently, there are no early molecular indicators that would predict progression from BE to EAC. As the only permanent residents of the epithelium, stem cells have been implicated in this metaplastic progression. The aim of the present study was to determine the expression of doublecortin and CaM kinase-like-1 (DCAMKL-1) and other putative gastrointestinal stem cell markers in normal esophageal mucosa (NEM), BE, and EAC.

METHODS

Human NEM, BE, EAC, and multitissue microarrays were analyzed for DCAMKL-1, and immunohistochemically scored based on staining intensity and tissue involvement, with epithelia and stroma scored separately. Total RNA isolated from BE and paired NEM was subjected to real-time reverse-transcription-polymerase chain reaction analysis for DCAMKL-1, leucine-rich repeat-containing G-protein-coupled receptor (LGR5), and Musashi-1 (Msi-1) mRNA expression.

RESULTS

DCAMKL-1 was minimally expressed in squamous NEM, but increased in BE (with and without dysplasia) and EAC tissues. In EAC, we found increased stromal DCAMKL-1 staining compared to adjacent epithelia. Within the submucosa of dysplastic BE tissues, an increase in the endothelial cell expression of DCAMKL-1 was observed. Finally, an upregulation of DCAMKL-1, LGR5, and Msi-1 mRNA was seen in BE compared to squamous NEM.

CONCLUSIONS

In the present study, we report the progressive increase of DCAMKL-1 expression in BE from dysplasia to EAC. Furthermore, there was an increase in putative stem cell markers DCAMKL-1, LGR5, and Msi-1 mRNA. Taken together, these data suggest that the regulation of resident stem cells might play an important role in the progression of BE to EAC.