Cellular macromolecules play important roles in cellular behaviors and biological processes. In the current work, cancer (KLN205), normal (MSFs) and mouse embryonic stem cells (mESCs) are compared using ATR-FTIR spectroscopy. Modifications in the composition, concentration, structure and function-related changes in the cellular components were deciphered using the infrared spectra. Our results revealed that cancer and embryonic stem cells are very similar but highly different from the normal cells based on the spectral variations in the protein, lipid, carbohydrate and nucleic acid components. The longest lipid acyl chains exist in mESCs, while cancer cells harbor the lowest lipid amount, short lipid acyl chains, a high content of branched fatty acids and thin cell membranes. The highest cellular growth rate and accelerated cell divisions were observed in the cancer cells. However, the normal cells harbor low nucleic acid and glycogen amounts but have a higher lipid composition. Any defect in the signaling pathways and/or biosynthesis of these cellular parameters during the embryonic-to-somatic cell transition may lead to physiological and molecular events that promote cancer initiation, progression and drug resistance. We conclude that an improved understanding of both similarities and differences in the cellular mechanisms among the cancer, normal and mESCs is crucial to develop a potential clinical relevance, and ATR-FITR can be successfully used as a novel approach to gain new insights into the stem cell and cancer research. We suggest that targeting the cellular metabolisms (glycogen and lipid) can provide new strategies for cancer treatment.

High recurrence and metastatic behavior patterns are the most important reasons for the failure of treatment strategies in patients with colon cancer.Cancer stem cells (CSCs), which are considered root of cancer, are thought to be associated with therapy resistance, relapse, and metastasis, and, therefore, targeting CSCs rather than the bulk population may be an effective approach. In cancer studies, there is an increasing interest in close friendship between epithelial-mesenchymal transition (EMT) and CSCs. Triptolide (TPL) isolated from Chinese herb Tripterygium wilfordii has important effects on the prevention of migration and metastasis as well as cytotoxic effect against cancer cells. The potential lethal efficacy of TPL on CSCs that is highly resistant to the drug is an unsolved mystery. Fundamentally, the present study basically aims to find answers to two questions: (a) is it possible to target colon CSCs with TPL? and (b) what are the mechanisms underlying TPL's potential to eliminate CSCs? Cytotoxic effects of TPL on CSCs were evaluated by WST-1 and Muse count and viability assays. Apoptosis assay and cell-cycle analysis were performed to investigate the inhibitory effect of TPL. Moreover, the effects of TPL on spheroid formation capacity, migration, and EMT processes, which are associated with CSC phenotype, were also investigated. The results revealed that TPL triggered cell death and apoptosis and altered cell cycle distribution.Moreover, TPL significantly reduced the snail slug and twist expressions associated with EMT. TPL has been shown to be effective in colon CSCs by in vitro experiments, and it might be a highly effective agent against colon cancer has been implicated in need of supporting in vivo and clinical studies. K E Y W O R D S apoptosis, cancer stem cell, colon cancer, epithelial-mesenchymal transition, migration, spheroid formation, triptolide

Trabectedin (Yondelis, ET-743) is a marine-derived tetrahydroisoquinoline alkaloid. It is originally derived from the Caribbean marine tunicate Ecteinascidia turbinata and currently produced synthetically. Trabectedin is active against a variety of tumor cell lines growing in culture. The present study focused on the effect of trabectedin in cell proliferation, cell cycle progression, apoptosis and spheroid formation in prostate cancer stem cells (CSCs). Cluster of differentiation (CD) 133+high/CD44+high prostate CSCs were isolated from the DU145 and PC-3 human prostate cancer cell line through flow cytometry. We studied the growth-inhibitory effects of trabectedin and its molecular mechanisms on human prostate CSCs and non-CSCs. DU-145 and PC-3 CSCs were treated with 0.1, 1, 10 and 100 nM trabectedin for 24, 48 and 72 h and the growth inhibition rates were examined using the sphere-forming assay. Annexin-V assay and immunofluorescence analyses were performed for the detection of the cell death. Concentration-dependent effects of trabectedin on the cell cycle were also evaluated. The cells were exposed to the different doses of trabectedin for 24, 48 and 72 h to evaluate the effect of trabectedin on the number and diameter of spheroids. According to the results, trabectedin induced cytotoxicity and apoptosis at the IC50 dose, resulting in a significant increase expression of caspase-3, caspase-8, caspase-9, p53 and decrease expression of bcl-2 in dose-dependent manner. Cell cycle analyses revealed that trabectedin induces dose-dependent G2/M-phase cell cycle arrest, particularly at high-dose treatments. Three-dimensional culture studies showed that trabectedin reduced the number and diameter of spheroids of DU145 and PC3 CSCs. Furthermore, we have found that trabectedin disrupted cell-cell interactions via E-cadherin in prostasphere of DU-145 and PC-3 CSCs. Our results showed that trabectedin inhibits cellular proliferation and accelerates apoptotic events in prostate CSCs; and may be a potential effective therapeutic agent against prostate cancer.

Flavopiridol is a flavone that inhibits several cyclin-dependent kinases and exhibits potent growth-inhibitory activity, apoptosis and G1-phase arrest in a number of human tumor cell lines. Flavopiridol is currently undergoing investigation in human clinical trials. The present study focused on the effect of flavopiridol in cell proliferation, cell cycle progression and apoptosis in prostate cancer stem cells (CSCs). Therefore, cluster of differentiation 133 (CD133)+high/CD44+high prostate CSCs were isolated from the DU145 human prostate cancer cell line. The cells were treated with flavopiridol in a dose- and time-dependent manner to determine the inhibitory effect. Cell viability and proliferation were analyzed and the efficiency of flavopiridol was assessed using the sphere-forming assay. Flavopiridol was applied to monolayer cultures of CD133high/CD44high human prostate CSCs at the following final concentrations: 100, 300, 500 and 1000 nM. The cultures were incubated for 24, 48 and 72 h. The half maximal inhibitory concentration (IC50) value of the drug was determined as 500 nM for monolayer cells. Dead cells were analyzed prior and subsequent to exposure to increasing flavopiridol doses. Annexin-V and immunofluorescence analyses were performed for the evaluation of apoptotic pathways. According to the results, flavopiridol treatment caused significant growth inhibition at 500 and 1000 nM when compared to the control at 24 h. G0/G1 analysis showed a statistically significant difference between 100 and 500 nM (P<0.005), 100 and 1000 nM (P<0.001), 300 and 1000 nM (P<0.001), and 500 and 1000 nM (P<0.001). Flavopiridol also significantly influenced the cells in the G2/M phase, particularly at high-dose treatments. Flavopiridol induced growth inhibition and apoptosis at the IC50 dose (500 nM), resulting in a significant increase in immunofluorescence staining of caspase-3, caspase-8 and p53. In conclusion, the present results indicated that flavopiridol could be a useful therapeutic agent for prostate CSCs by inhibiting tumor growth and malignant progression, and inducing apoptosis.