CD133 expression pattern distinguishes intraductal papillary mucinous neoplasms from ductal adenocarcinomas of the pancreas

Pancreatic cancer cell-derived exosomes induce epithelial-mesenchymal transition in human pancreatic cancer cells themselves partially via transforming growth factor β1

Distant metastasis is a dismal prognostic factor of pancreatic cancer. Metastasis is established in several steps, but the mechanism underlying the very early stages remains unclear. Epithelial-mesenchymal transition (EMT) is involved in these stages. Although signaling molecules have been reported to induce EMT, the mechanism underlying their origin is unclear. In this study, we hypothesized that pancreatic cancer cell-derived exosomes induce EMT in cancer cells themselves, a notion we entertained because we found EMT in in vitro three-dimensional colonies of cancer cells, with vimentin-positive cells observed in some of the budding pancreatic cancer cells and in single cells outside the colony as well. First, we clarified that pancreatic cancer cell-derived exosomes induce EMT in cancer cells themselves. Next, we examined the involvement of transforming growth factor-β1 (TGF-β1), and TGF-β1 knock-down in pancreatic cancer cells with TGF-β1 siRNA significantly suppressed TGF-β1 gene expression in cancer cells, and exosomal TGF-β1 was significantly reduced in the secretory exosomes. Exosomes from TGF-β1 knock-down cells suppressed EMT induction in cancer cells themselves and TGF-β1 protein expression in target cells. Taken together, these findings suggest that TGF-β1 is involved in EMT induction via exosomes, results that may support the production of effective metastasis inhibitors.

Promoter hypermethylation of CD133/PROM1 is an independent poor prognosis factor for head and neck squamous cell carcinoma

PROM1 has played a pivotal role in the identification and isolation of tumor stem cells. This study aimed to assess the association between PROM1 promoter methylation and head and neck squamous cell carcinoma (HNSCC), and its diagnostic and prognostic value.Bioinformatic analysis was performed using data from the Cancer Genome Atlas-HNSC and Gene Expression Omnibus datasets.The results showed that PROM1 promoter was hypermethylated in HNSCCs compared with normal head and neck tissues (P = 4.58E-37). The area under the receiver-operating characteristic curve based on methylated PROM1 data was 0.799. In addition, PROM1 hypermethylation independently predicted poor overall survival (hazard ratio [HR]: 1.459, 95% confidence interval [CI]: 1.071-1.987, P = .016) and recurrence-free survival (HR: 1.729, 95% CI: 1.088-2.749, P = .021) in HNSCC patients. Moreover, PROM1 methylation was weakly negatively correlated with its mRNA expression (Pearson r = -0.148, P < .001).In summary, our study reveals that methylated PROM1 might serve as a valuable diagnostic biomarker and predictor of poor survival for HNSCC patients. PROM1 hypermethylation might partially contribute to its downregulation in HNSCC.

Prominin-like Regulates Longevity and Glucose Metabolism via Insulin Signaling in Drosophila

CD133, also called Prominin-1, is a biomarker for mammalian stem cells. It is involved in cell growth, development, and tumor biology. However, the function of CD133 at the organismal level has not been investigated. In this study, we found that prominin-like (promL) loss-of-function mutant flies show an extended life span and metabolic defects such as increased circulating carbohydrates, lipid storage, and starvation resistance. The messenger RNA expression levels of Drosophila insulin-like peptides (Dilps) were reduced in loss-of-function promL mutants. Furthermore, the level of phosphorylated AKT, a downstream component of insulin signaling, was lower in promL loss-of-function mutants than in the w− control flies. Importantly, the PromL protein is predominantly expressed in the pars intercerebralis region with insulin-producing cells of the adult brain. When we inhibited promL in insulin-producing cells, these flies showed an extended life span, metabolic defects, and reduced insulin signaling. These results indicate that the promL gene regulates longevity and glucose metabolism by controlling insulin signaling in Drosophila.

Gemcitabine Enhances Kras-MEK-Induced Matrix Metalloproteinase-10 Expression Via Histone Acetylation in Gemcitabine-Resistant Pancreatic Tumor-initiating Cells

OBJECTIVES

Advanced pancreatic ductal adenocarcinoma is resistant to systemic chemotherapy, resulting in a poor prognosis. We previously isolated a human pancreatic tumor-initiating cell line, KMC07, from a patient with acquired resistance to gemcitabine chemotherapy. To improve the anticancer effects of gemcitabine, we investigated the molecular mechanism of KMC07 cells' resistance to gemcitabine.

METHODS

KMC07 cells were treated with gemcitabine, then gene expression and functional analyses performed using microarray, the quantitative polymerase chain reaction, immunoblotting, immunohistochemistry, chromatin immunoprecipitation, and cell transplantation into nude mice.

RESULTS

KMC07 cells, but not BxPC-3, PANC-1, MIA PaCa-2, or AsPC-1 cells, expressed matrix metalloproteinase-10 mRNA, the expression level of which was enhanced by gemcitabine. KMC07 cells were shown to carry a constitutively active Kras mutation, and a MEK inhibitor suppressed matrix metalloproteinase-10 mRNA expression. Gemcitabine enhanced histone H3 acetylation at the matrix metalloproteinase-10 promoter, and a histone acetyltransferase inhibitor reduced gemcitabine-enhanced matrix metalloproteinase-10 mRNA expression. Gemcitabine induced expression of matrix metalloproteinase-10 protein in KMC07-derived pancreatic tumors in vivo.

CONCLUSIONS

We demonstrated constitutive activation of the Kras-MEK matrix metalloproteinase-10 signaling pathway in KMC07 cells that was enhanced by gemcitabine through histone acetylation. Our results may provide novel insights into gemcitabine-based treatment for gemcitabine-resistant pancreatic ductal adenocarcinoma.

CD90 and CD24 Co-Expression Is Associated with Pancreatic Intraepithelial Neoplasias

Thy-1 (CD90) has been shown to be a potential marker for several different types of cancer. However, reports on CD90 expression in pancreatic intraepithelial neoplasia (PanIN) lesions are still limited where PanINs are the most important precursor lesion of pancreatic ductal adenocarcinoma (PDAC). Herein, we investigate candidate markers for PanIN lesions by examining the distribution and trend of CD90 and CD24 expression as well as their co-expression in various stages of PanINs. Thirty cases of PanINs, which were confirmed histopathologically and clinically, were used to evaluate protein expression of CD90 and CD24 by immunofluoresence double staining. CD90 was found to be mainly expressed in stroma around lesion ducts while not observed in acini and islets in PanINs. CD90 also showed increased expression in PanIN III compared to PanIN III. CD24 was mainly present in the cytoplasm and membrane of pancreatic ductal epithelia, especially in the apical epithelium of the duct. CD24 had higher expression in PanIN III compared with PanIN IIIIII or PanIN III. CD90 was expressed around CD24 sites, but there was little overlap between cells that expressed each of these proteins. A correlation analysis showed that these two proteins have a moderate relationship with PanIN stages respectively. These results suggest that co-expression of CD90 and CD24 may have an important role in the development and progression of PanINs, which is also conducive to early detection and treatment of PDAC.

Identification of a novel subpopulation of tumor-initiating cells from gemcitabine-resistant pancreatic ductal adenocarcinoma patients

Pancreatic ductal adenocarcinoma is highly resistant to systemic chemotherapy. Although there are many reports using pancreatic cancer cells derived from patients who did not receive chemotherapy, characteristics of pancreatic cancer cells from chemotherapy-resistant patients remain unclear. In this study, we set out to establish a cancer cell line in disseminated cancer cells derived from gemcitabine-resistant pancreatic ductal adenocarcinoma patients. By use of in vitro co-culture system with stromal cells, we established a novel pancreatic tumor-initiating cell line. The cell line required its direct interaction with stromal cells for its in vitro clonogenic growth and passaging. Their direct interaction induced basal lamina-like extracellular matrix formation that maintained colony formation. The cell line expressed CD133 protein, which expression level changed autonomously and by culture conditions. These results demonstrated that there were novel pancreatic tumor-initiating cells that required direct interactions with stromal cells for their in vitro cultivation in gemcitabine-resistant pancreatic ductal adenocarcinoma. This cell line would help to develop novel therapies that enhance effects of gemcitabine or novel anti-cancer drugs.

CD133 expression is not an independent prognostic factor in stage II and III colorectal cancer but may predict the better outcome in patients with adjuvant therapy

Background

Cancer stem cells (CSCs) are notorious for their capacity of tumor progression, metastasis or resistance to chemo-radiotherapy. However, the undisputed role of cancer stem marker, CD133, in colorectal cancers (CRCs) is not clear yet.

Methods

We assessed 271 surgically-resected stage II and III primary CRCs with (171) and without (100) adjuvant therapy after surgery. CD133 expression was analyzed by immunohistochemical (IHC) staining and real-time RT-PCR. CD133 promoter methylation was quantified by pyrosequencing.

Results

The CD133 IHC expression was significantly correlated with mRNA expression (p=0.0257) and inversely correlated with the promoter methylation (p=0.0001). CD133 was expressed more frequently in rectal cancer (p=0.0035), and in moderately differentiated tumors (p=0.0378). In survival analysis, CD133 expression was not significantly correlated with overall survival (OS) (p=0.9689) as well as disease-free survival (DFS) (p=0.2103). However, CD133+ tumors were significantly associated with better OS in patients with adjuvant therapy compared to those without adjuvant therapy (p<0.0001, HR 0.125, 95% CI 0.052-0.299). But the patients with CD133- tumors did not show any significant difference of survival according to adjuvant therapy (p=0.055, HR 0.500, 95% CI 0.247-1.015).

Conclusions

In stage II and III CRCs, CD133 IHC expression may signify the benefit for adjuvant therapy although it is not an independent prognostic factor.

Prominin-1 (CD133) Reveals New Faces of Pancreatic Progenitor Cells and Cancer Stem Cells: Current Knowledge and Therapeutic Perspectives

Islet transplantation-based therapies were proven successful for type 1 diabetes mellitus, but an extreme shortage of pancreatic islets has motivated recent efforts to develop renewable sources of islet-replacement tissue. Pancreatic progenitor cells hold a promising potential, yet attempts at their prospective isolation are scarce due to the lack of specific marker. We found that prominin-1 (often referred to as CD133 in humans) is expressed by the undifferentiated epithelial cells in the mouse embryonic pancreas. Putative pancreatic epithelial stem and progenitor cells were prospectively enriched in prominin-1(+) cell population by cell sorting and characterized. CD133 is also a cell surface marker of human pancreatic cancer stem cells (CSC), which are resistant to conventional treatments such as chemotherapy and radiotherapy. Therefore, a considerable interest in the specific targeting and eradication of CSC is emerging for the cancer therapy, and CD133 may represent a good molecular target. In this chapter, I will summarize our current knowledge about prominin-1/CD133 in mouse and human pancreas.

Distinctive expression of CD133 between intraductal papillary neoplasms of the bile duct and bile duct adenocarcinomas

AIM

  Intraductal papillary neoplasm of the bile duct (IPNB), a novel entity of biliary disease, is recently advocated as the counterpart of pancreatic intraductal papillary mucinous neoplasm (IPMN) because both are in common with a large amount of mucin production and papillary growth. Based on our recent finding that expression of CD133, a cancer stem cell marker, is lacking in pancreatic IPMN, we herein focused on CD133 expression of IPNB in comparison with intrahepatic cholangiocellular carcinoma (IHCCC) or hilar bile duct cancer (HBDC).

METHODS

  Expression of CD133 protein was immunohistochemically determined in patients with IPNB (n = 7), IHCCC (n = 16) or HBDC (n = 8). In addition, morphological and immunohistochemical mucin expression patterns were characterized in IPNB, and clinicopathological features including prognosis were compared between IPNB and other biliary tumors.

RESULTS

  The IPNB group included significantly more females than the other two groups, and had a longer survival time. While no CD133 expression was observed in IPNB tumor, 16.4% of cancer cells in IHCCC and 17.2% of cells in HBDC expressed CD133. Among seven patients with IPNB, six (86%) were morphologically the pancreatobiliary type and four of six showed mucin expression pattern of the typical pancreatobiliary type (MUC1+/MUC2-/MUC5AC+).

CONCLUSION

  Loss of CD133 expression supports the hypothesis that IPNB is a counterpart of pancreatic IPMN with a differing carcinogenesis from conventional bile duct adenocarcinomas.

Hypoxia induces tumor aggressiveness and the expansion of CD133-positive cells in a hypoxia-inducible factor-1α-dependent manner in pancreatic cancer cells

BACKGROUND

Intratumoral hypoxia is known to lead to increased aggressiveness and distant metastasis. However, the interplay underlying these actions is still unknown.

OBJECTIVE

We explored whether cancer cells might acquire a stem-like phenotype under hypoxia, consequently leading to an aggressive phenotype, including invasiveness and metastasis.

METHODS

Under normoxia (20% O(2)) or hypoxia (1% O(2)), the expression of CD133 (cancer stem cell marker), CXC chemokine receptor 4 (CXCR4) and hypoxia-inducible factor-1α (HIF-1α) was examined by RT-PCR and immunostaining using human pancreatic cancer cell lines. We also examined if hypoxia facilitates the invasiveness of CD133+ cancer cells. Furthermore, we transfected dominant active HIF-1α (HIF-1αΔODD) by the retroviral gene transfer and examined the effects both in vitro and in vivo.

RESULTS

Compared with normoxia, hypoxia elevated the expression of CD133, CXCR4 and HIF-1α. Moreover, hypoxia facilitated the invasiveness of CD133+ pancreatic cancer cells. The behavior of HIF-1αΔODD-transfected cells under normoxia was compatible with that of the parent cells under hypoxia. Furthermore, a xenograft model of HIF-1αΔODD cells showed aggressiveness, including metastasis and highly tumorigenic ability.

CONCLUSION

Hypoxia induces tumor aggressiveness associated with the expansion of CD133+ pancreatic cancer cells in a predominantly HIF-1α-dependent manner.

CD133 is a marker of gland-forming cells in gastric tumors and Sox17 is involved in its regulation

CD133 is a universal marker of tissue stem/progenitor cells as well as cancer stem cells, but its physiological significance remains to be elucidated. Here we examined the relationship between expression of CD133 and features of gastric epithelial cells, and found that CD133-positive (CD133[+]) tumor cell lines formed well-differentiated tumors while CD133-negative (CD133[-]) lines formed poorly differentiated ones when subcutaneously injected into nude mice. We also found that CD133(+) and CD133(-) cell populations co-existed in some cell lines. FACS analysis showed that CD133(+) cells were mother cells because CD133(+) cells formed both CD133(+) and CD133(-) cells, but CD133(-) cells did not form CD133(+) cells. In these cell lines, CD133(+) cells formed well-differentiated tumors while CD133(-) cells formed poorly differentiated ones. In human gastric cancers, CD133 was exclusively expressed on the luminal surface membrane of gland-forming cells, and it was never found on poorly differentiated diffuse-type cells. Considering that poorly differentiated tumors often develop from well-differentiated tumors during tumor progression, these results suggest that loss of expression of CD133 might be related to gastric tumor progression. Microarray analysis showed that CD133(+) cells specifically expressed Sox17, a tumor suppressor in gastric carcinogenesis. Forced expression of SOX17 induced expression of CD133 in CD133(-) cells, and reduction of SOX17 caused by siRNA in CD133(+) cells induced a reduction in the level of CD133. These results indicate that Sox17 might be a key transcription factor controlling CD133 expression, and that it might also play a role in the control of gastric tumor progression.

Visualization of CD44 and CD133 in normal pancreas and pancreatic ductal adenocarcinomas: non-overlapping membrane expression in cell populations positive for both markers

Tumor-initiating cells of pancreatic ductal adenocarcinoma (PDAC) have been isolated based on expression of either CD133 or CD44. The authors aimed to visualize pancreatic cells simultaneously expressing both these cell surface markers by employing the same antibodies commonly used in cell-sorting studies. Normal and diseased pancreatic tissue, including 51 PDAC cases, were analyzed. CD44 and CD133 expression was determined by immunohistochemical double staining on formalin-fixed material and subcellular protein distribution evaluated by immunofluorescence/confocal microscopy. In the normal pancreas, CD44 and CD133 were coexpressed in the centroacinar regions but in non-overlapping subcellular compartments. As expected, CD44 was found mainly basolaterally, whereas CD133 was present on the apical/endoluminal membrane. This was also the case in chronically inflamed/atrophic pancreatic tissue and in PDAC. In some malignant ducts, CD44 was found at the apical cell membrane adjacent to but never overlapping with CD133 expression. CD44 level was significantly associated with the patient's lymph node status. In conclusion, a CD44+/CD133+ cell population does exist in the normal and neoplastic pancreas. The preferentially centroacinar localization of the doubly positive cells in the normal parenchyma suggests that this population could be of particular interest in attempts to identify tumor-initiating cells in PDAC.

Pancreatic cancer stem cells - update and future perspectives

Solid tumours are the most common cancers and represent a major therapeutic challenge. The cancer stem cell hypothesis is an attractive model to explain the functional heterogeneity commonly observed in solid tumours. It proposes a hierarchical organization of tumours, in which a subpopulation of stem cell-like cells sustains tumour growth, metastasis, and resistance to therapy. We will present the most recent advances in the cancer stem cell field, with particular emphasis on pancreatic cancer as one of the deadliest human tumours, and highlight open questions and caveats to be addressed in future studies. There is increasing evidence that solid tumours including pancreatic cancer are hierarchically organized and sustained by a distinct subpopulation of cancer stem cells. However, direct evidence for the validity of the cancer stem cell hypothesis in human pancreatic cancer remains controversial due to the limitations of xenograft models but supportive data are now emerging from mouse models using related or different sets of markers for the identification of murine cancer stem cells. Therefore, while the clinical relevance of cancer stem cells remains a fundamental issue for this rapidly emerging field, current findings clearly suggest that specific elimination of these cells is possible and therapeutically relevant. Targeting of signalling pathways that are of particular importance for the maintenance and the elimination of cancer stem cell as the proposed root of the tumour may lead to the development of novel treatment regimens for pancreatic cancer. Here we will review the current literature on pancreatic cancer stem cells and the future perspective of this rapidly emerging field.