Proteomic profiling of cancer stem cells derived from primary tumors of HER2/Neu transgenic mice

Human epidermal growth factor receptor 2 (HER2) overexpression leads to mammary tumorigenesis and its elevated levels lead to increase in cancer stem cells (CSCs), invasion, and metastasis. CSCs are resistant to radiation/chemotherapeutic drugs and are believed to be responsible for recurrence/relapse of cancer. CSCs are isolated using flow cytometry based sorting, although reliable, this technology hinders the convenient identification of molecular targets of CSCs. Therefore to understand the molecular players of increased CSC through HER2 overexpression and to develop meaningful targets for combination therapy, we isolated and characterized breast CSCs through convenient tumorsphere culture. We identified the altered protein expression in CSC as compared to non‐CSC using LC‐MS/MS and confirmed those results using qRT‐PCR and Western blotting. Ferritin heavy chain 1 (FTH1) was identified as a candidate gene, which is involved in iron metabolism and iron depletion significantly decreased the self‐renewal of CSCs. We further performed in silico analysis of altered genes in tumorsphere and identified a set of genes (PTMA, S100A4, S100A6, TNXRD1, COX‐1, COX‐2, KRT14, and FTH1), representing possible molecular targets, which in combination showed a promise to be used as prognostic markers for breast cancer.     

LncRNA AWPPH and miRNA-21 regulates cancer cell proliferation and chemosensitivity in triple-negative breast cancer by interacting with each other

Long–non-coding RNAs (lncRNA) AWPPH promotes the progression of liver and bladder cancer, indicating its oncogenic role. The current study aimed to explore the involvement of AWPPH in triple-negative breast cancer (TNBC). In the current study, we found that plasma levels of lncRNA AWPPH and microRNA-21 (miRNA-21) were upregulated in patients with TNBC than in healthy controls, and the upregulation of plasma lncRNA AWPPH and miRNA-21 distinguished early-stage patients with TNBC from healthy controls. Plasma levels of lncRNA AWPPH and miRNA-21 were significantly and positively correlated in both patients with TNBC and healthy controls. LncRNA AWPPH and miRNA-21 overexpression led to promoted cancer cells proliferation and improved cancer cell viability under carboplatin treatment, while lncRNA AWPPH small interfering RNA (siRNA) silencing played an opposite role. In addition, miRNA-21 overexpression attenuated the effects of lncRNA AWPPH siRNA silencing on of cancer cell behaviors. LncRNA AWPPH overexpression led to upregulated miRNA-21 in TNBC cells, while miRNA-21 overexpression also led to significantly upregulated lncRNA AWPPH expression. Therefore, lncRNA AWPPH and miRNA-21 may regulate cancer cell proliferation and chemosensitivity in TNBC by interacting with each other.     

Clinical significance of blood-based miRNAs as diagnostic and prognostic nucleic acid markers in breast cancer: Comparative to conventional tumor markers

microRNAs (miRNAs) are implicated in carcinogenesis and their expression in biological fluids offer great potential as nucleic acid markers for cancer detection and progression. Authors investigated the expression level of miRNAs (miRNA-21, miRNA-126, and miRNA-155) to evaluate their role as diagnostic and prognostic markers for breast cancer compared with other commonly used protein-based markers (CEA and CA15-3). Serum samples from patients with breast cancer (n = 96), patients with benign breast lesion (n = 47), and healthy individuals (n = 39) were enrolled for detection of miRNA expression levels and protein-based tumor markers using fluorescent real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Correlation among investigated markers with clinicopathological factors and clinical outcomes were determined. Expression of miRNA-21 and miRNA-155 revealed significant increases in patients with breast cancer compared with both benign and control groups, the same result was reported for tumor markers; on the other hand, miRNA-126 was significantly decreased in breast cancer group as compared with the other two groups. miRNA frequencies were significantly related to clinical staging and histological grading as compared with tumor markers. Patients with breast cancer with increased miRNA-21 and miRNA-155 and decreased miRNA-126 expressions had significantly worse disease-free survival, while only miRNA-21 and miRNA-126 showed poor OS (P< 0.005). In conclusion, investigated miRNAs were superior over tumor markers for the early stage of breast cancer especially those with high-risk factor and their assessment in blood facilitates their role as a potential prognostic molecular marker.     

miR‐10b expression in breast cancer stem cells supports self‐renewal through negative PTEN regulation and sustained AKT activation

Cancer stem cells (CSCs) are linked to metastasis. Moreover, a discrete group of miRNAs (metastamiRs) has been shown to promote metastasis. Accordingly, we propose that miRNAs that function as metastatic promoters may influence the CSC phenotype. To study this issue, we compared the expression of 353 miRNAs in CSCs enriched from breast cancer cell lines using qRT–PCR analysis. One of the most altered miRNAs was miR‐10b, which is a reported promoter of metastasis and migration. Stable overexpression of miR‐10b in MCF‐7 cells (miR‐10b‐OE cells) promoted higher self‐renewal and expression of stemness and epithelial–mesenchymal transition (EMT) markers. In agreement with these results, inhibiting miR‐10b expression using synthetic antisense RNAs resulted in a decrease in CSCs self‐renewal. Bioinformatics analyses identified several potential miR‐10b mRNA targets, including phosphatase and tensin homolog (PTEN), a key regulator of the PI3K/AKT pathway involved in metastasis, cell survival, and self‐renewal. The targeting of PTEN by miR‐10b was confirmed using a luciferase reporter, qRT–PCR, and Western blot analyses. Lower PTEN levels were observed in CSCs, and miR‐10b depletion not only increased PTEN mRNA and protein expression but also decreased the activity of AKT, a downstream PTEN target kinase. Correspondingly, PTEN knockdown increased stem cell markers, whereas AKT inhibitors compromised the self‐renewal ability of CSCs and breast cancer cell lines overexpressing miR‐10b. In conclusion, miR‐10b regulates the self‐renewal of the breast CSC phenotype by inhibiting PTEN and maintaining AKT pathway activation.     

CAFs外泌体通过上调ABCB5诱导乳腺癌细胞化疗耐药

目的:探讨肿瘤相关成纤维细胞(CAFs)诱导乳腺癌细胞耐药及其作用机制。方法:从临床样本中分离培养CAFs,获取条件培养基,并纯化外泌体。使用CAFs条件培养基或CAFs外泌体与CD44+的乳腺癌干细胞(CSCs)和CD44-的非干细胞亚群共培养,并用5氟尿嘧啶(5-FU)处理共培养的细胞,通过成球实验和CCK8实验检测细胞的自我更新能力和存活能力。抑制细胞中ABCB5的表达,检测5-FU对细胞存活能力的影响。结果:CAFs条件培养或外泌体处理的CSCs自我更新能力和对5-FU的耐药能力更强,成球能力和对5-FU耐药性上升约1.5-2倍。CAFs外泌体可提高CSCs中ABCB5的表达水平约4-5倍,抑制ABCB5可降低CSCs的耐药性至原来的约60-80%。结论:CAFs通过旁分泌外泌体增强CSCs的自我更新能力并通过上调CSCs中ABCB5的表达水平促进其对化疗药物的抵抗。     

miRNA-148a and miRNA-30c expressions as potential biomarkers in breast cancer patients

BackgroundBreast cancer is an extensively identified malignant tumor and is a prime cause of cancer mortalities in females. It has been shown that alteration of miRNAs expression (up or down regulation) can affect the initiation and progression of many malignancies. We aimed to evaluate the role of circulating miRNA-148a and miRNA-30c in female patients with breast cancer and estimate their usage as potential biomarkers in the diagnosis, prognosis and survival of breast cancer.MethodsThis study included 75 breast cancer female patients.They were compared with 55 apparently healthy female subjects. miRNAs expression analysis was assessed via real-time PCR.ResultsTo discriminate breast cancer patients from controls, miR-30c showed the best performance at a cut off value of ≤20.6 (AUC = 0.998, 97.33% sensitivity, 96.36% specificity, p < 0.001), followed by miR-148a (AUC = 0.995, 94.67% sensitivity, 90.91% specificity, p < 0.001 at a cut off value of ≤0.1), CA 15-3 (AUC = 0.930, 88.0% sensitivity, 81.82% specificity, p < 0.001 at a cut off value of >21.3), and finally CEA (AUC = 0.751, 70.67% sensitivity, 63.64% specificity, p < 0.001 at a cut off value of >2.5).ConclusionmiRNA-148a and miRNA-30c expressions were down regulated in female patients with breast cancer and might be considered as potential blood biomarkers. Both also might have rule in disease treatment and selection of therapeutic targets. Future studies are needed to improve their role in predicting response to treatment and prognosis.     

Chemoresistance in ovarian cancer linked to expression of microRNAs

Abstract

We evaluated the differential expression of several microRNAs (miRNAs) among malignant cells in ascites and matched omental metastasis in patients with epithelial ovarian cancer (EOC). Ascites and omental tumors were collected prospectively from five patients who were undergoing primary surgical cytoreduction. Patient samples were processed and treated with carboplatin, paclitaxel and combination chemotherapy. Cell viability was evaluated and miRNA profiling was performed on both tumor cells from ascites fluid and omental cake. Quantitative real-time PCR (RT-q-PCR) and western blots were used to evaluate expressions of miRNA-21 and miRNA -214 and associated proteins. Malignant cells in ascites showed greater cell viability when treated with carboplatin compared to omental metastasis. A significant up-regulation of miRNA-21 and miRNA-214 was observed in malignant cells of ascites compared to omental metastasis; this was confirmed by both cell viability assay and RT-q-PCR. Ours is the first report that demonstrates significant up-regulation of miRNA-21 and miRNA-214 in tumor cells from ascites of patients with EOC compared to omental metastasis. This finding has important implications for intrinsic carboplatin resistance in these patients.     

Mitochondrial metabolism in cancer stem cells: a therapeutic target for colon cancer

It has been proposed that the selective elimination of cancer stem cells (CSCs) using targeted therapy could greatly reduce tumor growth, recurrence, and metastasis. To develop effective therapeutic targets for CSC elimination, we aimed to define the properties of CSC mitochondria, and identify CSC-mitochondria-specific targets in colon cancer. We found that colon CSCs utilize mitochondrial oxidative phosphorylation (OXPHOS) to produce ATP. We also found that forkhead box protein 1 (FOXM1)-induced peroxiredoxin 3 (PRDX3) maintains the mitochondrial function, and the FOXM1/PRDX3 mitochondrial pathway maintains survival of colon CSCs. Furthermore, FOXM1 induces CD133 (PROM1/prominin 1) expression, which maintains the stemness of colon CSCs. Together, our findings indicate that FOXM1, PRDX3, and CD133 are potential therapeutic targets for the elimination of CSCs in colon cancer. [BMB Reports 2015; 48(10): 539-540]     

Epigenetic reprogramming of breast cancer cells by valproic acid occurs regardless of estrogen receptor status

Estrogen receptors (ERs) are a recognized prognostic factor and therapeutic target in breast cancer. The loss of ER expression relates to poor prognosis, poor clinical outcome and impairs the use of anti-estrogenic treatment. Histone deacetylase inhibitors are candidate drugs for cancer therapy. Among them, valproic acid (VPA) is a long used and safe anti-epileptic drug. We studied the biological consequences of the chromatin remodeling action of VPA in a normal human mammary epithelial cell line and in ERalpha-positive and ERalpha-negative breast cancer cell lines. In these cells and regardless of their ER status, VPA-induced cell differentiation, as shown by increased milk lipids production, decreased expression of the CD44 antigen and growth arrest in the G(0)-G(1) phase of the cell cycle. These effects were accompanied by decreased Rb phosphorylation, hyperacetylation of the p21(WAF1/CIP1) gene promoter and increased p21 protein expression. Only in breast cancer cells, cyclin B1 expression was decreased and the cells accumulated also in G(2). ERalpha expression decreased in ERalpha-positive, increased in ERalpha-negative and was unchanged in normal mammary epithelial cells, as did the expression of progesterone receptor, a physiological ERalpha target. VPA decreased the expression of the invasiveness marker pS2 in ERalpha-positive breast cancer cells, but did not cause its re-expression in ERalpha-negative cells. Overall, these data suggest that in both ERalpha-positive and -negative malignant mammary epithelial cells VPA reprograms the cells to a more differentiated and "physiologic" phenotype that may improve the sensitivity to endocrine therapy and/or chemotherapy in breast cancer patients.     

Combination of dasatinib and curcumin eliminates chemo-resistant colon cancer cells

Metastatic colorectal cancer remains a serious health concern with poor patient survival. Although 5-Fluorouracil (5-FU) or 5-FU plus oxaliplatin (FOLFOX) is the standard therapy for colorectal cancer, it has met with limited success. Recurrence of the tumor after chemotherapy could partly be explained by the enrichment of the chemo-resistant sub-population of cancer stem cells (CSCs) that possess the ability for self-renewal and differentiation into different lineages in the tumor. Therefore development of therapeutic strategies that target CSCs for successful treatment of this malignancy is warranted. The current investigation was undertaken to examine the effectiveness of the combination therapy of dasatinib (a Src inhibitor) and curcumin (a dietary agent with pleiotropic effect) in inhibiting the growth and other properties of carcinogenesis of chemo-resistant colon cancer cells that are enriched in CSCs sub-population. Remnants of spontaneous adenomas from APC ^{Min +/-} mice treated with dasatinib and/or curcumin were analyzed for several cancer stem cell markers (ALDH, CD44, CD133 and CD166). Human colon cancer cells HCT-116 (p53 wild type; K-ras mutant) and HT-29 (p53 mutant; K-ras wild type) were used to generate FOLFOX resistant (referred to as CR) cells. The effectiveness of the combination therapy in inhibiting growth, invasive potential and stemness was examined in colon cancer CR cells. The residual tumors from APC ^{Min +/-} mice treated with dasatinib and/or curcumin showed 80-90% decrease in the expression of the CSC markers ALDH, CD44, CD133, CD166. The colon cancer CR cells showed a higher expression of CSCs markers, cell invasion potential and ability to form colonospheres, compared to the corresponding parental cells. The combination therapy of dasatinib and curcumin demonstrated synergistic interactions in CR HCT-116 and CR HT-29 cells, as determined by Calcusyn analysis. The combinatorial therapy inhibited cellular growth, invasion and colonosphere formation and also reduced CSC population as evidenced by the decreased expression of CSC specific markers: CD133, CD44, CD166 and ALDH. Our data suggest that the combination therapy of dasatinib and curcumin may be a therapeutic strategy for re-emergence of chemo-resistant colon cancer by targeting CSC sub-population.     

A trans-platinum(II) complex induces apoptosis in cancer stem cells of breast cancer

Recent accumulating evidence has supported the notion that tumors have hierarchically organized heterogeneous cell populations and a small subpopulation of cells, termed cancer stem cells (CSCs), are responsible for tumor initiation, maintenance as well as drug resistance. Therefore, targeting the CSCs along with the other cancer cells has been the most important topic during the last decade. In the present study, we evaluated the cytotoxic activity of trans-[PtCl₂(2-hepy)₂] [2-hepy = 2-(2-hydroxyethyl) pyridine] complex and the mechanism of cell death in breast CSCs. Stemness markers, Oct-4 and Sox2, were determined in mammospheres by western blotting. Cytotoxicity was assessed using the ATP viability assay. Cell death was fluorescently visualized and further confirmed by flow cytometry as well as gene expression analysis. The Pt(II) complex significantly reduced the cell viability, prevented mammosphere formation and disrupted mammosphere structures in a dose-dependent manner (0–100 μM). The mode of cell death was apoptosis and it was shown by the presence of caspase 3/7 activity, Annexin V-FITC positivity, decreased mitochondrial membrane potential and increased expressions of pro-apoptotic genes (TNFRSF10A and HRK). Interestingly, necroptosis was also observed by the evidence of increased MLKL expression. In conclusion, the Pt(II) complex seems to be a highly promising anticancer compound due to its promising cytotoxic activity on CSCs. Therefore, it deserves in vivo further studies for the proof-of-concept.     

Fibroblast-Derived Exosomes Contribute to Chemoresistance through Priming Cancer Stem Cells in Colorectal Cancer

Chemotherapy resistance observed in patients with colorectal cancer (CRC) may be related to the presence of cancer stem cells (CSCs), but the underlying mechanism(s) remain unclear. Carcinoma-associated fibroblasts (CAFs) are intimately involved in tumor recurrence, and targeting them increases chemo-sensitivity. We investigated whether fibroblasts might increase CSCs thus mediating chemotherapy resistance. CSCs were isolated from either patient-derived xenografts or CRC cell lines based on expression of CD133. First, CSCs were found to be inherently resistant to cell death induced by chemotherapy. In addition, fibroblast-derived conditioned medium (CM) promoted percentage, clonogenicity and tumor growth of CSCs (i.e., CD133+ and TOP-GFP+) upon treatment with 5-fluorouracil (5-Fu) or oxaliplatin (OXA). Further investigations exhibited that exosomes, isolated from CM, similarly took the above effects. Inhibition of exosome secretion decreased the percentage, clonogenicity and tumor growth of CSCs. Altogether, our findings suggest that, besides targeting CSCs, new therapeutic strategies blocking CAFs secretion even before chemotherapy shall be developed to gain better clinical benefits in advanced CRCs.     

Human pancreatic cancer stem cells: implications for how we treat pancreatic cancer

Pancreatic cancer has the worst prognosis of any major malignancy, with an annual death rate that approximates the annual incidence rate. Delayed diagnosis, relative chemotherapy and radiation resistance and an intrinsic biologic aggressiveness all contribute to the abysmal prognosis associated with pancreatic cancer. Answers to the frustrating effort to find effective therapies for pancreatic cancer may be gained through a renewed perspective on tumorigenesis as a process governed by a select population of cells, termed cancer stem cells (CSCs). Cancer stem cells, like their normal counterparts, have the properties of self-renewal and multilineage differentiation and possess inherently heightened DNA damage response and repair mechanisms that make them difficult to eradicate. Initially discovered in leukemias, researchers have identified CSCs in several solid-organ malignancies including breast, brain, prostate, and colon cancers. We have recently identified a CSC population in human pancreatic cancers. These pancreatic CSC represent 0.5% to 1.0% of all pancreatic cancer cells and express the cell surface markers CD44, CD24, and epithelial-specific antigen. Pancreatic CSCs have been shown to be resistant to standard chemotherapy and radiation, and devising specific therapies to target this distinct cell population is likely needed to identify effective therapies to treat this dismal disease.