Clinical implications of stem cell gene Oct-4 expression in breast cancer

Clinical implications of cancer stem cell-like side population cells in human laryngeal cancer

In this study, we try to detect and isolate the cancer stem cell-like side population cells (SP) from the laryngeal carcinoma cell line and primary laryngeal carcinoma and explore the clinical implications of SP cells in laryngeal carcinoma. The SP cells and non-side population cells (NSP) cells were sorted by Hoechst 33342 through FACS. The proliferation capacity, invasion ability, migration ability, and tumorigenic activity of the SP cells were evaluated. In addition, the association between the SP cells ratio and the prognostic factors of laryngeal cancer was analyzed. As a result, the percentage of the SP cells in Hep-2 cells was 5.1 %. The SP cells depicted float colonies, but the NSP cells failed to generate the typical cell spheres. The clone formation ratios were 47.47 ± 10.20 % vs. 4.98 ± 1.41 % in the flat plates and 46.82 ± 5.67 % vs. 12.53 ± 3.51 % in the soft agar for SP and NSP cells (P = 0.01 and 0.01). The SP cells depicted a higher migrating potency than the NSP cells in both the transwell assay and scarification test (all P < 0.05). The matrigel invasion assay showed that the artificial basement membrane penetration rate of SP cells was 39.04 ± 4.78 %, which was higher than 25.16 ± 4.63 % of the NSP cells (P < 0.05). Only 10³ SP cells were able to form tumors in mice, whereas 10⁴ NSP cells failed to form tumors. The SP cells were correlated with the differentiation, lymph node metastasis, and clinical stage of the laryngeal cancers. In conclusion, SP cells may be a potential prognostic factor of laryngeal cancer.

Expression of the Pluripotency Transcription Factor OCT4 in the Normal and Aberrant Mammary Gland

Breast cancers with lactating features, some of which are associated with pregnancy and lactation, are often poorly differentiated, lack estrogen receptor, progesterone receptor, and HER2 expression and have high mortality. Very little is known about the molecular mechanisms that drive uncontrolled cell proliferation in these tumors and confer lactating features. We have recently reported expression of OCT4 and associated embryonic stem cell self-renewal genes in the normal lactating breast and breastmilk stem cells (hBSCs). This prompted us to examine OCT4 expression in breast cancers with lactating features and compare it with that observed during normal lactation, using rare specimens of human lactating breast. In accordance with previous literature, the normal resting breast (from non-pregnant, non-lactating women) showed minimal OCT4 nuclear expression (0.9%). However, this increased in the normal lactating breast (11.4%), with further increase in lactating adenomas, lactating carcinomas, and pregnancy-associated breast cancer (30.7–48.3%). OCT4 was expressed in the epithelium and at lower levels in the stroma, and was co-localized with NANOG. Comparison of normal non-tumorigenic hBSCs with OCT4-overexpressing tumorigenic breast cell lines (OTBCs) demonstrated upregulation of OCT4, SOX2, and NANOG in both systems, but OTBCs expressed OCT4 at significantly higher levels than SOX2 and NANOG. Similar to hBSCs, OTBCs displayed multi-lineage differentiation potential, including the ability to differentiate into functional lactocytes synthesizing milk proteins both in vitro and in vivo. Based on these findings, we propose a hypothesis of normal and malignant transformation in the breast, which centers on OCT4 and its associated gene network. Although minimal expression of these embryonic genes can be seen in the breast in its resting state throughout life, a controlled program of upregulation of this gene network may be a potential regulator of the normal remodeling of the breast toward a milk-secretory organ during pregnancy and lactation. Deregulation of this gene network either within or outside pregnancy and lactation may lead to aberrant breast cell proliferation and malignant transformation, suggesting a role of these genes in both normal lactation and breast oncogenesis.

Downregulation of OCT4 promotes differentiation and inhibits growth of BE (2)-C human neuroblastoma I-type cells

In in vitro continuous culture, N (neuroblastic)-, S (substrate adherent)- and I (intermediate)-type cells were identified in human neuroblastoma (NB), where I-type is recognized as a stem cell type. Octamer-binding protein 4 (OCT4) is a cell marker used to identify the stemness of cells, whose roles in regulating I-type NB cells have yet to be fully elucidated. In the present study, we assessed the differentiation regulation role of OCT4 in BE (2)-C of I-type cells. We demonstrated that downregulation of OCT4 expression in BE (2)-C was associated with reduced cell proliferation and loss of colony formation ability on soft agar, and prompted BE (2)-C cells to differentiate to S-type cells. By contrast, overexpression of OCT4 increased cell proliferation and colony formation ratio, but no obvious differentiation promotion was observed. Furthermore, induced differentiation of BE (2)-C cells to S-type by 5-bromo-2'-deoxyuridine (BrdUrd) was accompanied by reduced expression of OCT4.

Markers of stem cells in human ovarian granulosa cells: is there a clinical significance in ART?

Background

The purpose of the study was to determine the incidence of gene expression of Oct-4 and DAZL, which are typical markers for stem cells, in human granulosa cells during ovarian stimulation in women with normal FSH levels undergoing IVF or ICSI and to discover any clinical significance of such expression in ART.

Methods

Twenty one women underwent ovulation induction for IVF or ICSI and ET with standard GnRH analogue-recombinant FSH protocol. Infertility causes were male and tubal factor. Cumulus–mature oocyte complexes were denuded separately and granulosa cells were analyzed for each patient separately using quantitative reverse-transcription–polymerase chain reaction analysis for Oct-4 and DAZL gene expression with G6PD gene as internal standard.

Results

G6PD and Oct-4 mRNA was detected in the granulosa cells in 47.6% (10/21). The median of Oct-4 mRNA/G6PD mRNA was 1.75 with intra-quarteral range from 0.10 to 98.21. The OCT-4 mRNA expression was statistically significantly correlated with the number of oocytes retrieved; when the Oct-4 mRNA expression was higher, then more than six oocytes were retrieved (p=0.037, Wilcoxon rank-sum). No detection of DAZL mRNA was found in granulosa cells. There was no additional statistically significant correlation between the levels of Oct-4 expression and FSH basal levels or estradiol peak levels or dosage of FSH for ovulation induction. No association was found between the presence or absence of Oct-4 mRNA expression in granulosa cells and ovarian response to gonadotropin stimulation. Also, no influence on pregnancy was observed between the presence or absence of Oct-4 mRNA expression in granulosa cells or to its expression levels accordingly.

Conclusions

Expression of OCT-4 mRNA, which is a typical stem cell marker and absence of expression of DAZL mRNA, which is a typical germ cell marker, suggest that a subpopulation of luteinized granulosa cells in healthy ovarian follicles (47.6%) consists of stem cells, which are not originated from primordial germ cells. Absence of Oct-4 gene expression in more than half of the cases means probably the end of the productive journey of these cells, towards the oocyte.

Clinical implications of CD44+/CD24- tumor cell ratio in breast cancer

PURPOSE

To investigate the association of the CD44+/CD24- cancer stem cell (CSC) ratio with clinicopathologic features and its prognostic value in breast cancer.

MATERIALS AND METHODS

The CD44+/CD24- CSC ratio was determined in formalin-fixed, paraffin-embedded breast cancer tissues from 1350 breast cancer patients by double immunofluorescence staining. The Cox regression analysis was performed to evaluate whether the CD44+/CD24- CSC ratio is an independent prognostic factor. The Kaplan-Meier survival analysis was conducted to determine the association of the CD44+/CD24- CSC ratio with cancer-specific survival.

RESULTS

The mean average CSC ratio in clinical specimens was 8.06% (range from 1.02% to 37.54%). The CD44+/CD24- CSC ratio, together with histological grade, molecular type, and clinical stage, was independent prognostic factors of breast cancer. The CD44+/CD24- CSC ratio was significantly correlated with estrogen receptor (ER), progesterone receptor (PR), and Ki67, but not the Her-2 and P53 status. Furthermore, the CD44+/CD24- CSC ratio was significantly associated with 5-year breast cancer-specific survival in 1242 cases (88.97% vs. 75.76% vs.52.11% for ≤ 5%, 5%-10% and >10% CSC ratio cases, respectively, p=0.001). The linear regression analysis showed that the CSC ratio was borderlinely correlated with the N stage related (R=0.397 p=0.06), and significantly correlated with distant recurrence (R=0.487, p=0.01) in 1350 specimens. After the survival analysis, the 5-year distant recurrence rates were (57/435 [13.10%] vs. 159/594 [26.77%] vs. 114/213 [53.52%] for ≤ 5%, 5%-10%, and >10% CSC ratio cases, p=0.001).

CONCLUSION

The CSC ratio was an independent prognostic factor for breast cancer as well as a potential predictive marker for chemotherapy in breast cancer.

Breastmilk is a novel source of stem cells with multilineage differentiation potential

The mammary gland undergoes significant remodeling during pregnancy and lactation, which is fuelled by controlled mammary stem cell (MaSC) proliferation. The scarcity of human lactating breast tissue specimens and the low numbers and quiescent state of MaSCs in the resting breast have hindered understanding of both normal MaSC dynamics and the molecular determinants that drive their aberrant self-renewal in breast cancer. Here, we demonstrate that human breastmilk contains stem cells (hBSCs) with multilineage properties. Breastmilk cells from different donors displayed variable expression of pluripotency genes normally found in human embryonic stem cells (hESCs). These genes included the transcription factors (TFs) OCT4, SOX2, NANOG, known to constitute the core self-renewal circuitry of hESCs. When cultured in the presence of mouse embryonic feeder fibroblasts, a population of hBSCs exhibited an encapsulated ESC-like colony morphology and phenotype and could be passaged in secondary and tertiary clonogenic cultures. While self-renewal TFs were found silenced in the normal resting epithelium, they were dramatically upregulated in breastmilk cells cultured in 3D spheroid conditions. Furthermore, hBSCs differentiated in vitro into cell lineages from all three germ layers. These findings provide evidence that breastmilk represents a novel and noninvasive source of patient-specific stem cells with multilineage potential and establish a method for expansion of these cells in culture. They also highlight the potential of these cells to be used as novel models to understand adult stem cell plasticity and breast cancer, with potential use in bioengineering and tissue regeneration.

Nanog: a potential biomarker for liver metastasis of colorectal cancer

BACKGROUND

At present, the relationship between Nanog expression and the biological behavior and prognosis of colorectal cancer is still unclear.

AIM

The purpose of this study was to evaluate the expression and regulatory effects of Nanog in colorectal cancer and the correlation between Nanog protein expression and the prognosis of patients with colorectal cancer.

MATERIALS AND METHODS

The differential expression of genes between CD133+ tumor cells and CD133- tumor cells were detected using RT(2) Profiler™ PCR Array. The Nanog mRNA expression level was detected by RT-PCR and the protein level was detected using immunohistochemistry staining. The relationship between Nanog expression and clinicopathological parameters of colorectal cancer was determined.

RESULTS

Nanog were expressed significantly higher in CD133+ tumor cells compared to CD133- tumor cells. It was observed that 72 (20.00 %) of the 360 cases positively expressed Nanog. Univariate analyses indicated that Nanog expression was related to histological grade, lymph node metastasis, TNM stage, and liver metastasis (P = 0.005, 0.001, 0.001 and 0.012, respectively). Spearman correlation analysis showed that Nanog expression has a linear correlation to liver metastasis (P = 0.001). After conducting multivariate analysis, histological grade, TNM stage, and Nanog were found to be related to liver metastasis (P = 0.020, 0.01 and 0.001, respectively). In the Cox regression test, the histological grade, Lymph node metastasis, TNM stage, liver metastasis, and Nanog were detected as the independent prognostic factors (P = 0.02, 0.045, 0.01, 0.001 and 0.001, respectively).

CONCLUSIONS

Nanog protein may be a potential biomarker for postoperative liver metastasis of colorectal cancer.

CD74: a potential novel target for triple-negative breast cancer

The expression status of CD74 in breast cancer stem cells and its clinical implications was evaluated in order to lay a foundation for managing breast cancer. Five hundred and eighty breast cancer specimens were enrolled in the study. The relationship between the CD74 protein and clinicopathological parameters as well as prognosis was subsequently determined. In total, 468 (80.69 %) of the 580 breast cases showed CD74-positive expression. After universal analysis, CD74 was observed to be related to lymph node metastasis and triple-negative breast cancer (P = 0.01 and 0.001). Moreover, CD74 expression has a line correlation with lymph node metastasis and triple-negative breast cancer (P = 0.02 and 0.001). Furthermore, periostin was shown to attain a significantly more distant liver metastasis and worse disease-specific survival than those with none or low-expressed CD74 protein (P = 0.001). In the Cox regression test, CD74 protein was detected as an independent prognostic factor (P = 0.001). CD74 is consistently expressed in triple-negative subgroups of breast cancer and might be a new potential marker for triple-negative breast cancer.

Increased expression of OCT4 is associated with low differentiation and tumor recurrence in human hepatocellular carcinoma

Octamer binding transcription factor 4 (OCT4), a key transcription factor required to maintain self-renewal and pluripotency of human and mouse embryonic stem cells, has been recently identified to be associated with tumorigenesis and malignant transformation of many types of cancers. This study was to determine the roles of OCT4 in HCC recurrence and their impact on the clinical outcome of HCC patients. Western blot and immunohistochemical stains were used to detect the expression of OCT4 protein in 152 HCC tissues and 40 cirrhosis tissues, as well as in 6 human HCC cell lines and normal hepatocytes. OCT4 expression in HCC cell lines and tumor tissues was higher than in normal hepatocytes and cirrhosis tissues. Overexpression of OCT4 was significantly associated with low differentiation and tumor recurrence. Patients with elevated expression of OCT4 protein usually carried a poor overall survival and high recurrence rate. Multivariate analysis showed that OCT4 expression was an independent predictive factor for HCC patients survival. OCT4 might serve as a promising biomarker for the diagnosis of highly recurrent cases of HCC and could be used as a valuable indicator for predicting the prognosis of HCC.

CD44+/CD24- ovarian cancer cells demonstrate cancer stem cell properties and correlate to survival

Cancer cells with the surface marker profile CD44+/CD24- have previously been described to possess cancer stem cell-like properties. This manuscript evaluates those properties in ovarian cancer cell lines. The proportion of CD44+/CD24- cells corresponded to the clinical aggressiveness of each ovarian cancer cell line histologic subtype. CD44+/CD24- cells demonstrated enhanced progressive differentiation as well as showing a 60-fold increase in Matrigel invasion in both SKOV3 and OV90 cell lines (p < 0.001 each) compared to other phenotypes. CD44+/CD24- demonstrated significant resistance to all chemotherapy agents used in all cell lines, with a 71-93 % increase in resistance compared with baseline. Using a threshold of 25 % CD44+/CD24- ovarian cancer cells found in ascites, patients with >25 % CD44+/CD24- were significantly more likely to recur (83 vs. 14 %, p = 0.003) and had shorter median progression-free survival (6 vs. 18 months, p = 0.01). In conclusion, the CD44+/CD24- phenotype in ovarian cancer cells demonstrate cancer stem cell-like properties of enhanced differentiation, invasion, and resistance to chemotherapy. This CD44+/CD24- phenotype correlates to clinical endpoints with increased risk of recurrence and shorter progression-free survival in patients with ovarian cancer.

Efficient enrichment of hepatic cancer stem-like cells from a primary rat HCC model via a density gradient centrifugation-centered method

BACKGROUND

Because few definitive markers are available for hepatic cancer stem cells (HCSCs), based on physical rather than immunochemical properties, we applied a novel method to enrich HCSCs.

METHODOLOGY

After hepatic tumor cells (HTCs) were first isolated from diethylinitrosamine-induced F344 rat HCC model using percoll discontinuous gradient centrifugation (PDGC) and purified via differential trypsinization and differential attachment (DTDA), they were separated into four fractions using percoll continuous gradient centrifugation (PCGC) and sequentially designated as fractions I-IV (FI-IV). Morphological characteristics, mRNA and protein levels of stem cell markers, proliferative abilities, induced differentiation, in vitro migratory capacities, in vitro chemo-resistant capacities, and in vivo malignant capacities were determined for the cells of each fraction.

FINDINGS

As the density of cells increased, 22.18%, 11.62%, 4.73% and 61.47% of primary cultured HTCs were segregated in FI-FIV, respectively. The cells from FIII (density between 1.041 and 1.062 g/ml) displayed a higher nuclear-cytoplasmic ratio and fewer organelles and expressed higher levels of stem cell markers (AFP, EpCAM and CD133) than cells from other fractions (P<0.01). Additionally, in vitro, the cells from FIII showed a greater capacity to self-renew, differentiate into mature HTCs, transit across membranes, close scratches, and carry resistance to chemotherapy than did cells from any other fraction; in vivo, injection of only 1×10(4) cells from FIII could generate tumors not only in subcutaneous tissue but also in the livers of nude mice.

CONCLUSIONS

Through our novel method, HCSC-like cells were successfully enriched in FIII. This study will greatly contribute to two important areas of biological interest: CSC isolation and HCC therapy.

Prognostic significance of NANOG and KLF4 for breast cancer

BACKGROUND

Some of the induced pluripotent stem cell (iPS cell)-inducing factors have been reported to be expressed in breast cancer. The aim of the present study was to examine the relationship between the expression of iPS cell-inducing factors and the prognosis of breast cancer patients.

METHODS

In 100 breast cancer patients, the expression of c-MYC, KLF4, NANOG, OCT4, and SOX2 was determined by immunohistochemistry using a tissue microarray analysis.

RESULTS

Patients with strong expression of NANOG had significantly lower disease-free survival (DFS) and overall survival rates than those with weak expression of NANOG (P = 0.004 and 0.033, respectively). In contrast, patients with strong expression of KLF4 had better DFS (P = 0.014).

CONCLUSIONS

Strong expression of NANOG is an indicator of a poor prognosis for breast cancer patients, whereas KLF4 is a favorable prognostic indicator. Our results suggest that NANOG stimulates the growth and metastasis of breast cancer cells, whereas KLF4 inhibits these processes.

Flow cytometry in cancer stem cell analysis and separation

In recent years, a special type of cancer cell--the cancer stem cell (CSC)--has been identified and characterized for different tumors. CSCs may be responsible for the recurrence of a tumor following a primarily successful therapy and are thought to bear a high metastatic potential. For the development of efficient treatment strategies, the establishment of reliable methods for the identification and effective isolation of CSCs is imperative. Similar to their stem cell counterparts in bone marrow or small intestine, different cluster of differentiation surface antigens have been characterized, thus enabling researchers to identify them within the tumor bulk and to determine their degree of differentiation. In addition, functional properties characteristic of stem cells can be measured. Side population analysis is based on the stem cell-specific activity of certain ATP-binding cassette transporter proteins, which are able to transport fluorescent dyes out of the cells. Furthermore, the stem cell-specific presence of aldehyde dehydrogenase isoform 1 can be used for CSC labeling. However, the flow cytometric analysis of these CSC functional features requires specific technical adjustments. This review focuses on the principles and strategies of the flow cytometric analysis of CSCs and provides an overview of current protocols as well as technical requirements and pitfalls. A special focus is set on side population analysis and analysis of ALDH activity. Flow cytometry-based sorting principles and future flow cytometric applications for CSC analysis are also discussed.

Co-expression of Oct-4 and Nestin in human breast cancers

The aim is to investigate the clinical implications of the Oct-4 and Nestin protein in human breast cancers. A total of 346 cases including 26 fresh and 320 paraffin-embedded tumor tissues were selected for characterizing the frequency of CD44(+)CD24(-) tumor cells by flow cytometry and the differential expression of the stem cell-related genes between CD44(+)CD24(-) and non-CD44(+)CD24(-) tumor cells was analyzed by PCR Array and immunofluorescence. In comparison with the non-CD44(+)CD24(-) tumor cells, the CD44(+)CD24(-), particularly for those with high percentage of Oct-4(+) and Nestin(+), tumor cells had higher tumorigenicity by forming mammospheres in vitro. More importantly, 42 (13.125%) out of 320 tumor tissues were positive for Oct-4 and Nestin staining. Universal analysis and multivariate analysis revealed that the expression of Oct-4 and Nestin was associated significantly with younger age, pathogenic degrees, lymph node metastasis and triple-negative breast cancer independently (P < 0.05) as well as shorter survival (P = 0.001). Oct-4 and Nestin were important regulators of the development of breast cancer, and Oct-4 and Nestin may be used as predictors for the prognosis of breast cancers.