Colon Cancer Stem Cells Markers Research Articles

Olfactomedin 4 produces dysplasia but suppresses metastasis of colon cancer.

Development of colorectal cancer (CRC) is regulated by a series of genetic and microenvironmental alterations. Olfactomedin 4 (OLFM4) is a secreted glycoprotein that is highly expressed in the gastrointestinal tract and modulates inflammation. However, the role of OLFM4 in CRC is uncertain. Here we aimed to explore the function of OLFM4 in CRC in vivo and in vitro. The mRNA expression of OLFM4 was up-regulated in precursor lesions with dysplasia or ulcerative colitis but was reduced in CRC. OLFM4 neutralizing antibody suppressed inflammation-mediated early-stage CRC formation in an AOM/DSS colitis-associated cancer model. OLFM4 knockdown cells exhibited increased cell proliferation and motility in vitro and in vivo. Ablation of OLFM4 increased tumor growth and metastasis in xenograft experiments. In addition, OLFM4 knockdown cells showed elevated expression of colon cancer stem cell markers including CD133, resulting in increased metastasis via epithelial-mesenchymal transition signaling. This study demonstrated that OLFM4 regulates inflammation and cancer progression differently; ablation of OLFM4 promotes cancer metastasis via stemness and epithelial-mesenchymal transition. These results suggest a new route for controlling cancer progression and metastasis.

DPEP1 promotes drug resistance in colon cancer cells by forming a positive feedback loop with ASCL2.

Drug resistance is an important factor affecting the efficacy of chemotherapy in patients with colon cancer. However, clinical markers for diagnosing drug resistance of tumor cells are not only a few in number, but also low in specificity, and the mechanism of action of tumor cell drug resistance remains unclear. Dipeptidase 1 (DPEP1) expression was analyzed using the cancer genome atlas (TCGA) and genotype-Tissue Expression pan-cancer data. Survival analysis was performed using the survival package in R software to assess the prognostic value of DPEP1 expression in colon cancer. Correlation and Venn analyses were adopted to identify key genes. Immunohistochemistry, western blot, qRT-PCR, Co-immunoprecipitation, and dual-luciferase reporter experiments were carried out to explore the underlying associations between DPEP1 and Achaete scute-like 2 (ASCL2). MTT assays were used to evaluate the role of DPEP1 and ASCL2 in colon cancer drug resistance. DPEP1 was highly expressed in colon cancer tissues. DPEP1 expression correlated negatively with disease-specific survival but not with overall survival. Bioinformatics analysis and experiments showed that the expressions of DPEP1 and ASCL2 in colon cancer tissues were markedly positively correlated. Mechanistic research indicated that DPEP1 enhanced the stability of protein ASCL2 by inhibiting its ubiquitination-mediated degradation. In turn, ASCL2 functioned as a transcription factor to activate the transcriptional activity of the DPEP1 gene and boost its expression. Furthermore, DPEP1 also could enhance the expression of colon cancer stem cell markers (LGR5, CD133, and CD44), which strengthened the tolerance of colon cancer cells to chemotherapy drugs. Our findings reveal that the DPEP1 enhances the stemness of tumor cells by forming a positive feedback loop with ASCL2 to improve resistance to chemotherapy drugs.

Suppressive effect of \u03b1-mangostin for cancer stem cells in colorectal cancer via the Notch pathway

BackgroundSince colon cancer stem cells (CSCs) play an important role in chemoresistance and in tumor recurrence and metastasis, targeting of CSCs has emerged as a sophisticated strategy for cancer therapy. α-mangostin (αM) has been confirmed to have antiproliferative and apoptotic effects on cancer cells. This study aimed to evaluate the selective inhibition of αM on CSCs in colorectal cancer (CRC) and the suppressive effect on 5-fluorouracil (5-FU)-induced CSCs.MethodsThe cell viability assay was performed to determine the optimal concentration of αM. A sphere forming assay and flow cytometry with CSC markers were carried out to evaluate the αM-mediated inhibition of CSCs. Western blot analysis and quantitative real-time PCR were performed to investigate the effects of αM on the Notch signaling pathway and colon CSCs. The in vivo anticancer efficacy of αM in combination with 5-FU was investigated using a xenograft mouse model.ResultsαM inhibited the cell viability and reduced the number of spheres in HT29 and SW620 cells. αM treatment decreased CSCs and suppressed the 5-FU-induced an increase in CSCs on flow cytometry. αM markedly suppressed Notch1, NICD1, and Hes1 in the Notch signaling pathway in a time- and dose-dependent manner. Moreover, αM attenuated CSC markers CD44 and CD133, in a manner similar to that upon DAPT treatment, in HT29 cells. In xenograft mice, the tumor and CSC makers were suppressed in the αM group and in the αM group with 5-FU treatment.ConclusionThis study shows that low-dose αM inhibits CSCs in CRC and suppresses 5-FU–induced augmentation of CSCs via the Notch signaling pathway.

Curcumin may be a potential adjuvant treatment drug for colon cancer by targeting CD44

Despite the considerable advances in treatment method development, the mortality rate related to colon cancer still ranks the fifth in all tumor-related diseases. Recently, there has been growing evidences supporting the existence of colon cancer stem cells (CSCs) might be one of the main causes for initiation, progression and recurrence of colon cancer. Curcumin has been shown to possess anticancer activities. It has also been suggested that curcumin was effective against colon CSCs by coupling with CD44, a robust marker and functional important molecule for colorectal CSC. In the present study, we confirmed that curcumin can inhibit the proliferation, colony formation, migration and tumor sphere formation of colon cancer cells. Results from real-time PCR and western blotting had suggested that curcumin could down-regulate the expression of CD44. Moreover, results from flow cytometry had further revealed that curcumin could decrease the proportion of CD44+ colon cancer cells. After the expression of CD44 had been knocked down by using siRNA, the inhibition effects of curcumin against CD44+ colon cancer cells were observed to be reduced significantly. Moreover, it had been observed that the cellular uptake of curcumin was significantly higher in CD44+ colon cancer cells. Results from flow cytometry had shown that curcumin could induce apoptosis in CD44+ colon cancer cells. Altogether, our results suggested that curcumin might be an adjuvant drug for the treatment of colorectal cancer by targeting CD44.

Correlation of clinicopathological features and LGR5 expression in colon adenocarcinoma

Colon cancer stem cells (CSCs) are closely related to tumorigenesis and treatment response, and LGR5 is currently the most robust and reliable CSC marker in colorectal cancer (CRC). However, LGR5 expression in CRC tumor budding (TB) is not well understood. We examined the clinicopathological and prognostic significance of LGR5 in CRC TB. LGR5 expression was evaluated by RNAscope, a newly developed RNA in situ hybridization technique, using a tissue microarray consisting of 55 patient samples of TB in colon adenocarcinoma (CA) selected from the medical archives at our hospital. Patients were stratified into negative and positive LGR5 expression groups. Tumor-infiltrating lymphocytes (TILs) and histological grade were lower in the LGR5-positive group compared with the LGR5-negative group (P = .0407 and P = .0436, respectively). There was no significant difference in overall survival between the LGR5-positive group and the LGR5-negative group (log-rank test, P = .6931). LGR5 expression did not remain a predictor of prognosis in univariate analysis (OR = 0.84, 95% CI: 0.33–2.02, P = .6928). LGR5 expression may be affected by TILs, which have been demonstrated to be associated with worse prognosis in the budding area of CA and is an important potential marker of prognosis.

Quercetin pretreatment enhances the radiosensitivity of colon cancer cells by targeting Notch-1 pathway

Cancer stem-like cells are rare immortal cells within tumor, which are thought to play important roles in ionizing radiation (IR) therapy-resistance. Quercetin is a natural flavonoid with potential anti-cancer properties without significant cytotoxicity in normal tissues. In this study, we demonstrated that quercetin-IR combination treatment exhibited more dramatic anti-cancer effect than either quercetin or IR treatment alone via targeting colon cancer stem cells (CSCs) and inhibiting the Notch-1 signaling. These effects were further verified by in vivo studies which showed remarkable decrease of the CSCs markers and the expression of Notch-1 signaling proteins in human colon cancer xenografts in nude mice. Co-treatment with quercetin and low dose of radiation significantly reduced the expressions of all five proteins of γ-secretase complex in HT-29 and DLD-1 cells. In addition, ectopic expression of the Notch intracellular domain (NICD) partly reversed the inhibition effects by the combination therapy. In conclusion, our results indicated that the combination of quercetin (20 μM) and IR (5Gy) might be a promising therapeutic strategy for colon cancer treatment by targeting colon cancer stem-like cells and inhibiting the Notch-1 signaling. In future studies, we intend to further explore the potential therapeutic efficacy of the quercetin-radiation combination treatment in clinical trials.

Effects of down-regulation of IGF2 gene on the biological characteristics of HCT116 colon cancer stem cells

Objective: To investigate the effect of down-regulation of insulin-like growth factor 2 (IGF2) gene on the biological characteristics of HCT116 colon cancer stem cells (CSCs). Methods: Flow cytometry sorting technology was used to isolate CSCs from colon cancer cell line HCT116 by a monoclonal antibody against CD133; serum free floating culture assay was used for the enrichment of CSCs. The proportion of CD133(+) cells was analyzed by flow cytometry; CSCs were identified by sphere culturing, immunofluorescence analysis and soft agar clone formation. RT-qPCR method was used to examine transcriptional level of IGF2 gene in CSCs. Western blotting was used to examine IGF2 protein expression in CSCs. siRNA was used to establish IGF2 transient knock down model in CSCs. Cell proliferation array, cell cycle and apoptosis analysis, cell invasion array and colony forming assay were used to further examine the role of IGF2 on the biological characteristics of colon CSCs. Results: CSCs were successfully isolated from HCT116 cell lines, which were cultured to form cell spheres in serum-free stem cell culture medium. We found that the morphology of sphere-forming-like cells after several passages maintained the same characteristics as that of the first passage. The results of immunofluorescence showed that CSC markers including CD133 and ALDH continued positively expressing on the cell surface of CSCs, and flow cytometry analysis showed that more than 90% of the spheroid cells remained CD133 positive. The clone formation rate of non-CSCs group and CSCs group were (28.10±2.66)% and (43.73±2.30)% respectively, with significant difference (P<0.01). The RT-qPCR results showed that the transcriptional level IGF2 gene in non-CSCs group and CSCs group were (1.06±0.24) and (2.17±0.51) respectively, with significant difference (P<0.05). The western blot results showed that the protein expression of IGF2 in CSCs group and non-CSCs group were (1.10±0.55) and (2.14±0.23) respectively, with significant difference (P<0.05). Knockdown of IGF2 significantly decreased the percentage of CD133(+) cells in CSCs and cell proliferation (P<0.01). Knockdown of IGF2 increased the percentage of G(2)/M phase (23.46% of siNC group vs 60.14% of siIGF2 group) and cell apoptosis (2.80% of siNC group vs 40.70% of siIGF2 group), while decreased the percentage of G(0)/G(1) phase (40.77% of siNC group vs 17.73% of siIGF2 group). The invasion results showed that the number of cells penetrating into the basement surface in siNC group and siIGF2 group was (109.00±16.37) and (54.00±8.19) respectively, with significant difference (P<0.01). The rate of sphere-forming of colon CSCs in siNC group and siIGF2 group were (51.70±7.42)% and (21.27±2.35)% respectively, with significant difference (P<0.01). The clone formation rate of siNC group and siIGF2 group were (37.20±3.87)% and (18.23±2.25)% respectively, with significant difference (P<0.01). Conclusion: IGF2 gene plays an important role in maintaining the biological characteristics of colon cancer stem cells and promoting self-renewal and stemness of colon CSCs.

The effects of tramadol on cancer stem cells and metabolic changes in colon carcinoma cells lines

Opioids are widely used in the treatment of cancer related pain. They mainly exert their effects on opioid receptors. The most common opioid in the treatment of pain is morphine. Previous studies show that they may have effects on cancer cell behavior. These may include apoptosis, angiogenesis, invasion, inflammation and immune reactions. Tramadol, also an opioid is widely used in the treatment of cancer pain and is not well studied in cancer behavior. We aimed to investigate the effects of tramadol on cancer stem cells and metabolic changes in colon carcinoma cells.We used Colo320 (ATCC, CCL-220), Colo741 (ECACC, 93052621) and HCT116 (ATCC, CCL-247) colon cancer cell lines. CD133 was considered colon cancer stem cell marker and used to sort CD133+ and CD133− cells by magnetic cell sorting. MTT (mitochondria-targeted therapeutics) technique was used to detect tramadol's cytotoxic effect on cells in the study groups. Cells were treated with 1 mg/kg, 1.5 mg/kg and 2 mg/kg tramadol for 24 h at 37 °C and 5% CO2.Caspase-3, Ki-67, Bcl-2 and VGEF distributions were performed using indirect immunoperoxidase staining for immunohistochemical analysis. The study showed that tramadol has triggering effect on apoptosis in Colo320 colon cancer stem cells.

Enrichment of cancer stem‐like cells by the induction of epithelial‐mesenchymal transition using lentiviral vector carrying E‐cadherin shRNA in HT29 cell line

A better understanding of cancer stem cells (CSCs) may facilitate the prevention and treatment of cancers. Epithelial-mesenchymal transition (EMT) is a process activated during invasion and metastasis of tumors. EMT induction in normal and tumor cells makes them more resistant to chemotherapy. E-cadherin is a membrane protein and plays a role in tumor invasion, metastasis, and prognosis. Downregulation of E-cadherin is a hallmark of EMT. Here, we created a model of cancer stem-like cells enrichment via EMT induction using E-cadherin downregulation in HT29 cell line using a lentiviral vector carrying shRNA. We aimed to evaluate cancer and anti-CSC chemotherapeutics screening. The markers of EMT and CSCs were assessed and compared with control cells using flow cytometry, real-time PCR, immunocytochemistry, western blot, migration assay, invasion assay, and colony formation assay. The transduced cells showed a mesenchymal morphology. High levels of EMT-related proteins were also expressed. These results confirmed that the transduced cells underwent EMT. In addition, we observed an increased population of E-cadherin-downregulated HT29 cell line among the cells expressing colon CSC markers (CD133+ and CD44+ ) after EMT induction. E-cadherin-downregulated cells were morphologically like mesenchymal cells, and the number of CD133+ - and CD44+ -cells (CSC-like cells) increased. These cells can be used as stable models to study cancer cells and screening of antitumor therapeutics.

RETRACTED: Correlation of clinicopathological features and LGR5 expression in colon adenocarcinoma

Colon cancer stem cells (CSCs) are closely related to tumorigenesis and treatment response, and LGR5 is currently the most robust and reliable CSC marker in colorectal cancer (CRC). However, LGR5 expression in CRC tumor budding (TB) is not well understood. We examined the clinicopathological and prognostic significance of LGR5 in CRC TB. LGR5 expression was evaluated by RNAscope, a newly developed RNA in situ hybridization technique, using a tissue microarray consisting of 55 patient samples of TB in colon adenocarcinoma (CA) selected from the medical archives at our hospital. Patients were stratified into negative and positive LGR5 expression groups. Inflammatory cell infiltration was weaker and histological grade was lower in the LGR5-positive group compared with the LGR5-negative group (P = 0.0407 and P = 0.0436, respectively). There was a significant difference in OS between the LGR5-positive group and LGR5-negative group (log-rank test, P = 0.0088). Cox proportional hazards models revealed that the LGR5-positive group (Overall survival (OS) = 0.37, 95% CI: 0.17-0.79, P = 0.0101) had better OS. LGR5 expression may be affected by inflammatory cell infiltration in the budding area of CA and is an important potential marker of prognosis.

Abstract 1338: Citrobacter rodentium-induced autophagy protects cancer stem cells to facilitate tumor development and progression in the colons of Apc1638N/+ mice

Abstract Background: Colon cancer stem cells (CCSCs) play crucial roles in tumorigenesis, chemotherapy resistance, tumor recurrence and cancer metastasis. Autophagy, a lysosomal degradation and recycling process implicated in cancer progression and therapy resistance, plays an important role in host defense against enteric pathogen, Citrobacter rodentium (CR), and controls CR-induced infectious colitis. However, the role of CR infection in autophagy induction and CCSCs-driven neoplastic transformation has not been studied. Aim: To examine whether CR-induced autophagy protects CCSCs to promote colon cancer development and progression. Methods: Both male and female Apc1638N/+ mice from NCI repository were either infected with CR (109CFUs) and additionally given AOM (@10mg/Kg bw) or treated with a combination of AOM+DSS (7 days @ 3%). ApcMin/+ and BLT1-/-;ApcMin/+ mice were used as additional models mimicking FAP in humans. Apc++ mice were used as controls. Standard histologic, biochemical and molecular approaches were implemented. Results: CR infection induced significant autophagy in Apc++ mice with formation of autophagosomes and increases in LC3B and Beclin-1 staining at 12-27 days post-infection. While the frequency of tumor development in the colons of uninfected mice was lower, CR infection-induced tumor incidence in the colon was associated with increases in Ki-67, β-catenin, EZH2 and CCSC marker Dclk1/AcTub levels, respectively. In response to AOM treatment of CR-infected mice, we discovered colons to respond better compared to small intestine, with increases in Ki-67 and EZH2 staining although increases in Dclk1/AcTub levels were less pronounced compared to AOM-treated alone. When Apc1638N/+ mice were subjected to AOM/DSS treatment, colonic tumors exhibited more pronounced changes in Ki-67, EZH2 and Dclk1/AcTub staining than tumors of the small intestine. These tumors were also highly inflamed as was revealed by infiltration of F4/80+ macrophages and CD3+ lymphocytes. Interestingly, CD3 co-localized with β-catenin in these tumors, indicating contribution of Wnt signaling in the tumorigenic process. Both intestinal and colonic tumors also stained positive for migrating cancer stem cell markers CD110 and CDCP1, respectively. Colonic tumors additionally exhibited stromal positivity, suggesting local spread. Further investigation of tumors from AOM/DSS-treated Apc1638N/+ mice revealed significant autophagy wherein Dclk1/AcTub+ cells co-localized with Atg7 and p62, suggesting that autophagy may be protecting CCSCs. Both ApcMin/+ mice in response to CR infection and BLT1-/-;ApcMin/+ mice exhibited similar increases and co-localization of Dclk1/AcTub+ cells within the tumors with autophagic markers. Conclusion: CR-induced autophagy may protect CCSCs to promote colon cancer development and progression. Citation Format: Badal C. Roy, Ishfaq Ahmed, Venkatakrishna R. Jala, Bodduluri Haribabu, Shrikant Anant, Shahid Umar. Citrobacter rodentium-induced autophagy protects cancer stem cells to facilitate tumor development and progression in the colons of Apc1638N/+ mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1338.

Curcumin attenuates resistance to irinotecan via induction of apoptosis of cancer stem cells in chemoresistant colon cancer cells.

Resistance to conventional chemotherapeutic agents, including irinotecan (CPT‑11), 5-fluorouracil and capecitabine is a major cause for therapeutic failure in patients with colorectal cancer (CRC). Increasing evidence has demonstrated that cancer cells exhibiting stem cell-like characteristics are associated with the development of resistance to chemotherapeutic agents. As a plant polyphenol, curcumin has been demonstrated to have the ability to ameliorate resistance of CRC to chemotherapeutic agents, but the associations among curcumin, cancer stem cells (CSCs) and chemoresistance of CRC remain unclear. The present study established a CPT‑11-resistant colon cancer cell line, LoVo/CPT‑11 cells, and detected the expression levels of CSC identification markers [cluster of differentiation (CD)44, CD133, epithelial cell adhesion molecule (EpCAM) and CD24] in parental cells and CPT‑11-resistant cells. It was revealed that the expression levels of the colon CSC markers in LoVo/CPT‑11 cells were significantly higher compared those in parental cells at the mRNA and protein level. The effect of curcumin on the chemoresistance to CPT‑11 and the expression levels of CSC identification markers in LoVo/CPT‑11 cells separately treated with curcumin and CPT‑11 were further investigated. The results revealed that curcumin significantly attenuated chemoresistance to CPT‑11, and treatment with curcumin resulted in a significant reduction of the expression levels of CSC identification markers. Furthermore, a tumor sphere formation assay was used to enrich colon CSCs from LoVo/CPT‑11 cells, and demonstrated that curcumin efficiently diminished the traits of colon CSCs, as evidenced by the inability to form tumor spheres, the reduction in the expression of CSC identification markers, and apoptosis-induced effects on sphere-forming cells treated with curcumin alone or in combination with CPT‑11. Altogether, the present data demonstrated that curcumin attenuated resistance to chemotherapeutic drugs through induction of apoptosis of CSCs among colon cancer cells. These findings may provide novel evidence for the therapeutic application of curcumin in CRC intervention.

P53 positively regulates the expression of cancer stem cell marker CD133 in HCT116 colon cancer cells.

Colon cancer stem cells (CSCs), which are highly capable of self-renewal and proliferation, are involved in colon tumorigenesis and response to therapy. CD133 is considered the most robust surface marker for colorectal cancer stem cells. Although the TP53 gene is frequently mutated in colon cancer, it remains not fully understood whether and how tumor protein p53 (p53) is associated with CD133 expression in colon cancer cells. In the present study, the expression of the CSC biomarker CD133 was investigated in terms of p53 status in colorectal carcinoma HCT116 cells. p53 wild-type HCT116 (HCT116 p53+/+) and depleted HCT116 (HCT116 p53-/-) cells were used throughout this study. Cells carrying the CSC biomarkers CD133 and CD44 were examined by flow cytometry. A dual-luciferase reporter assay was employed to further confirm the transcriptional regulation of the CD133 promoter by p53. The results demonstrated that there was a significant difference in the % of CD133-positive cells between the HCT116 p53+/+ cell line (84.84±0.05%) and the HCT116 p53-/- cell line (4.13±0.02%). The mRNA expression levels of CD133 in HCT116 p53+/+ cells were also significantly higher compared with HCT116 p53-/- cells. Knockdown of p53 by specific small interfering RNA greatly reduced the expression of CD133 in HCT116 p53+/+ cells. Transcription factor binding site analysis indicated that there are several p53 binding elements in the CD133 promoter region. A dual-luciferase reporter assay further demonstrated the transcriptional activation of CD133 promoter by p53. In conclusion, these results suggest that p53 positively regulates the expression of CSC marker CD133 in the HCT116 human colon colorectal cancer cell line. p53 may be involved in the initiation and maintenance of colorectal cancer stem cells through regulating the expression of CD133.

A novel mechanism of lncRNA and miRNA interaction: CCAT2 regulates miR-145 expression by suppressing its maturation process in colon cancer cells

BackgroundAlthough both long and micro RNAs are emerging as important functional components in colorectal cancer (CRC) progression and metastasis, the mechanism of their interaction remains poorly understood. CCAT2 (Colon cancer-associated transcript-2), a long noncoding RNA (lncRNA), has been reported to be over-expressed in CRC and is found to promote tumor growth. miRNAs, a class of naturally occurring short RNAs negatively control the expression of target genes by cleaving mRNA or through translation repression. Recently, we reported that miR-145 and miR-21 cooperate to regulate colon cancer stem cell (CSC) proliferation and differentiation. Considering that CCAT2 is mainly located in the nucleus and miRNA maturation process begins in the nucleus, we hypothesize that CCAT2 selectively blocks miR-145 maturation process, resulting in decreased mature miR-145 affecting colon CSC proliferation and differentiation.MethodsThe levels of CCAT2 were manipulated by transfection of CCAT2 expression plasmid or knockdown by siRNA or by CRISPR/Cas9. Quantitative RT-PCR was performed to examine the expression of CCAT2 and pri-, pre- and mature miR-145/21. Fluorescence in situ hybridization (FISH) was used to visualize CCAT2 in the cells. In vitro processing of pri-miRNA-145 was performed using T7 RNA polymerase and recombinant human Dicer.ResultsWe have observed that modulated expression of CCAT2 regulates the expression of miR-145 in colon cancer HCT-116 and HT-29 cells. Knockout of CCAT2 increases miR-145 and negatively regulates miR-21 in HCT-116 cells, impairs proliferation and differentiation. In contrast, stable up-regulation of CCAT2 decreases mature miR-145 and increases the expression of several CSC markers in colon cancer cells. We have also observed that CCAT2 is enriched in the nucleus and correlates with the expression of pre-miR-145 but not pre-miR-21 in HCT-116 cells. These results indicate CCAT2 selectively blocks miR-145 maturation by inhibiting pre-miR-145 export to cytoplasm. Further, we revealed that CCAT2 blocks cleavage of pre-miR-145 by Dicer in vitro.ConclusionsOur results identify CCAT2 as a negative regulator of miRNA-145 biogenesis, and expose a novel mechanism of lncRNA-miRNA crosstalk.

AA-NAT, MT1 and MT2 Correlates with Cancer Stem-Like Cell Markers in Colorectal Cancer: Study of the Influence of Stage and p53 Status of Tumors.

The characterization of colon cancer stem cells (CSCs) may help to develop novel diagnostic and therapeutic procedures. p53 loss increases the pool of CSCs in colorectal cancer (CRC). Recent reports suggest that the oncostatic effects of melatonin could be related to its ability to kill CSCs. Although there are no data linking the loss of p53 function and melatonin synthesis or signaling in cancer, melatonin does activate the p53 tumor-suppressor pathway in this disease. In this work, we analyze whether the expression of melatonin synthesis and signaling genes are related to the expression of CSC markers and the implication of p53 status in samples from patients with CRC. Arylalkylamine N-acetyltransferase (AA-NAT), MT1, and MT2 expression decreased in tumor samples versus normal mucosa samples in mutated p53 (mtp53) tumors versus those with wild-type p53 (wtp53). Further, AA-NAT and MT2 expression were lower in advanced stages of the disease in wtp53 tumors. On the contrary, CD44 and CD66c expression was higher in tumor versus normal mucosa in wtp53 tumors. Additionally, CD44 expression was higher in advanced stages of the disease regardless of the p53 status. Patients with CD44highCD66chigh and wtp53 tumors in advanced stages showed low expression of AA-NAT and MT2 in wtp53 tumors. These results could indicate a possible interaction of these pathways in CRC.

Identification of High-Risk Aberrant Crypt Foci and Mucin-Depleted Foci in the Human Colon With Study of Colon Cancer Stem Cell Markers

BackgroundDuring colonoscopic screening, only macroscopic lesions will be identified, and these are usually the result of multiple genetic abnormalities. Magnification endoscopic detection of aberrant crypt foci (ACF), long before they acquire complex genetic abnormalities, is promising. However, the features of high-risk ACF-like lesions need to be identified. Materials and MethodsIn the present cross-sectional study, grossly visible normal mucosal flaps were shaved from 152 colectomies, including 96 colorectal cancer (CRC) cases and 56 controls (22 control specimens with disease with malignant potential and 34 without malignant potential). Methylene and Alcian blue stains were performed directly on the unfixed mucosal flaps to identify ACF and mucin-depleted foci (MDF). Detailed topographic analyses, with immunohistochemical staining for β-catenin and cancer stem cell (CSC) markers (CD44, CD24, and CD166) were performed. ResultsACF, MDF, and β-catenin–accumulated crypts were detected more in specimens with adjacent CRC. The left colon had ACF with a larger diameter and greater crypt multiplicity, density, and gyriform pit pattern and were considered the high-risk ACF group. MDF, more commonly associated with dysplasia, is also a marker of possible carcinogenesis. The CD44 CSC marker was significantly upregulated in ACF specimens compared with normal controls. Our 3-tier ACF-only pit pattern classification system showed better linearity with mucosal dysplasia than did the 6-tier Kudo classification. ConclusionHigh-risk ACF, when detected during chromoendoscopic screening, should be followed up. CSCs might play an important role in pathogenesis. Larger studies and genotypic risk stratification for definite identification of high-risk ACF are needed.

Bmi-1 promotes the invasion and migration of colon cancer stem cells through the downregulation of E-cadherin.

Metastasis and recurrence are the challenges of cancer therapy. Recently, mounting evidence has suggested that cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT) are critical factors in tumor metastasis and recurrence. The oncogene, Bmi-1, promotes the development of hematologic malignancies and many solid tumors. The aim of the present study was to elucidate the mechanisms through which Bmi-1 promotes the invasion and migration of colon CSCs (CCSCs) using the HCT116 colon cancer cell line. Sphere formation medium and magnetic-activated cell sorting were used to enrich and screen the CCSCs. CD133 and CD44 were regarded as markers of CCSCs and they were found to be co-expressed in the HCT116 colon cancer cell line. Colony formation assay, cell proliferation assay and viability assay using the Cell Counting Kit-8, and transplantation assay using nude mice injected with CCSCs were used to examine the CCSCs. The CD133+CD44+ HCT116 cells exhibited greater cloning efficiency, an enhanced proliferative ability, increased cell viability and stronger tumorigenicity; these cells were used as the CCSCs for subsequent experiments. In addition, the invasive and migratory abilities of the CD133+CD44+ HCT116 cells were markedly decreased when Bmi-1 was silenced by small interfering RNA (siRNA). The results of RT-qPCR and western blot analysis suggested that Bmi-1 had a negative effect on E-cadherin expression. On the whole, our findings suggest that Bmi-1 promotes the invasion and migration of CCSCs through the downregulation of E-cadherin, possibly by inducing EMT. Our findings thus indicate that Bmi-1 may be a novel therapeutic target for the treatment of colon cancer.

Expression Patterns of Cancer Stem Cell Markers During Specific Celecoxib Therapy in Multistep Rat Colon Carcinogenesis Bioassays.

The purpose of this study was to investigate the role of colon cancer stem cells (CSCs) during chemicallyinduced rat multi-step colon carcinogenesis with or without the treatment with a specific cyclooxygenase-2 inhibitor drug (celecoxib). Two experiments were performed, the first, a short term 12 week colon carcinogenesis bioassay in which only surrogate markers for colon cancer, aberrant crypt foci (ACF) lesions, were formed. The other experiment was a medium term colon cancer rat assay in which tumors had developed after 32 weeks. Treatment with celecoxib lowered the numbers of ACF, as well as the tumor volumes and multiplicities after 32 weeks. Immunohistochemical proliferating cell nuclear antigen (PCNA) labeling indexes LI (%) were downregulated after treatment by celecoxib. Also different cell surface antigens known to associate with CSCs such as the epithelial cell adhesion molecule (EpCAM), CD44 and CD133 were compared between the two experiments and showed differential expression patterns depending on the stage of carcinogenesis and treatment with celecoxib. Flow cytometric analysis demonstrated that the numbers of CD133 cells were increased in the colonic epithelium after 12 weeks while those of CD44 but not CD133 cells were increased after 32 weeks. Moreover, aldehyde dehydrogenase-1 activity levels in the colonic epithelium (a known CSC marker) detected by ELISA assay were found down-regulated after 12 weeks, but were up-regulated after 32 weeks. The data have also shown that the protective effect of celecoxib on these specific markers and populations of CSCs and on other molecular processes such as apoptosis targeted by this drug may vary depending on the genetic and phenotypic stages of carcinogenesis. Therefore, uncovering these distinction roles of CSCs during different phases of carcinogenesis and during specific treatment could be useful for targeted therapy.

ATPS-40FUNCTIONAL ROLES OF CD166/ALCAM IN GLIOBLASTOMA

Prognosis of glioblastoma multiforme (GBM) patients still remains poor. To improve its prognosis, it is important to identify new therapeutic targets. CD166/ALCAM is a member of the immunoglobulin superfamily and is widely expressed in various tissues such as neurons, fibroblasts, endothelial cells. Furthermore it is also reported to be a colon cancer stem cell marker as well as mesenchymal stem cell marker. CD166/ALCAM is also expressed on endothelial cells and is involved in angiogenesis. In this study, we aim to analyze the functional roles of CD166/ALCAM in glioblastoma. Transfection of CD166/ALCAM siRNA to U87MG and U251 cells significantly increased cell invasion in matrigel invasion assay without affecting cell proliferation. Transfection of ALCAM shRNA to U87MG glioblastoma cells significantly increased the tumor vessel area of U87MG xenograft in immune-deficient mice. Furthermore, over-expression of soluble isoform of CD166/ALCAM in U87MG GBM cells promoted tumor progression in intracranial transplant to immune-deficient mice. We also found that CD166/ALCAM was highly expressed on the CD133+ glioblastoma stem cell populations. In the CD133+ glioblastoma cell population, CD166/ALCAM positive cells were highly enriched with tumor-sphere-initiating cells in vitro. In summary, CD166/ALCAM is involved in glioblastoma invasion, angiogenesis, and tumor progression in glioblastoma. In addition CD166/ALCAM can be a candidate for glioblastoma progenitor markers. All these findings suggest that CD166/ALCAM is a potent therapeutic target against glioblastoma.

Outcomes Associated with Resident Participation in Laparoscopic Colorectal Surgery: Assessing the “Resident Effect”

Hwang, Grace S. MD; Moghadamyeghaneh, Zhobin MD; Phelan, Michael J. PhD; Mil, Steven MD; Pigazzi, Alessio MD, FACS; Stamos, Michael J. MD, FACS, FASCRS; Carmichael, Joseph C. MD, FACS; Hanna, Mark H. MD Author Information