Cancer stem cells in colorectal cancer from pathogenesis to therapy: Controversies and perspectives

Colorectal cancer remains one of the most common and lethal malignancies worldwide despite the use of various therapeutic strategies.A better understanding of the mechanisms responsible for tumor initiation and progression is essential for the development of novel,more powerful therapies.The traditional,so-called"stochastic model"of tumor development,which assumes that each cancer cell is tumorigenic,has been deeply challenged during the past decade by the identification of cancer stem cells(CSCs),a biologically distinct subset of cells within the bulk of tumor mass.This discovery led to the development of the hierarchical model of tumorigenesis which assumes that only CSCs have the ability to initiate tumor growth,both at primary and metastatic sites.This model implies that the elimination of all CSCs is fundamental to eradicate tumors and that failure to do so might be responsible for the occurrence of relapses and/or metastases frequently observed in the clinical management of colorectal cancer patients.Identification and isolation of CSCs is essential for a better understanding of their role in the tumorigenetic process and for the development of CSC-specific therapies.Several methods have been used for this purpose and many efforts have been focused on the identification of specific CSC-surface markers.This review provides an overview of the proposed roles of CSC in human colorectal tumorigenesis focusing on the most important molecules identified as CSC-specific markers in colorectal cancer and on the potential strategies for the development of CSC-targeted therapy.

Anti-tumor necrosis factor α therapy associates to type 17 helper T lymphocytes immunological shift and significant microbial changes in dextran sodium sulphate colitis

BACKGROUND Anti-tumor necrosis factor α(TNFα) represents the best therapeutic option to induce mucosal healing and clinical remission in patients with moderate-severe ulcerative colitis. On the other side gut microbiota plays a crucial role in pathogenesis of ulcerative colitis but few information exists on how microbiota changes following anti-TNFα therapy and on microbiota role in mucosal healing.AIM To elucidate whether gut microbiota and immune system changes appear following anti TNFα therapy during dextran sulfate sodium(DSS) colitis.METHODS Eighty C57 BL/6 mice were divided into four groups: "No DSS", "No DSS + antiTNFα", "DSS" and "DSS + anti-TNFα". "DSS" and "DSS + anti-TNFα" were treated for 5 d with 3% DSS. At day 3, mice whithin "No DSS+anti-TNFα" and"DSS+anti-TNFα" group received 5 mg/kg of an anti-TNFα agent. Forty mice were sacrificed at day 5, forty at day 12, after one week of recovery post DSS. The severity of colitis was assessed by a clinical score(Disease Activity Index), colon length and histology. Bacteria such as Bacteroides, Clostridiaceae, Enterococcaceae and Fecalibacterium prausnitzii(F. prausnitzii) were evaluated by quantitative PCR.Type 1 helper T lymphocytes(Th1), type 17 helper T lymphocytes(Th17) and CD4+ regulatory T lymphocytes(Treg) distributions in the mesenteric lymph node(MLN) were studied by flow cytometry.RESULTS Bacteria associated with a healthy state(i.e., such as Bacteroides, Clostridiaceae and F. prausnitzii) decreased during colitis and increased in course of anti-TNFαtreatment. Conversely, microorganisms belonging to Enterococcaceae genera,which are linked to inflammatory processes, showed an opposite trend.Furthermore, in colitic mice treated with anti-TNFα microbial changes were associated with an initial increase(day 5 of the colitis) in Treg cells and a consequent decrease(day 12 post DSS) in Th1 and Th17 frequency cells. Healthy mice treated with anti-TNFα showed the same histological, microbial and immune features of untreated colitic mice. "No DSS + anti-TNFα" group showed a lymphomononuclear infiltrate both at 5 th and 12 th d at hematoxylin and eosin staining, an increase of in Th1 and Th17 frequency at day 12, an increase of Enterococcaceae at day 5, a decrease of Bacteroides and Clostridiaceae at day 12.CONCLUSION Anti-TNFα treatment in experimental model of colitis improves disease activity but it is associated to an increase in Th17 pathway together with gut microbiota alteration.

Propionyl-L-carnitine hydrochloride for treatment of mild to moderate colonic inflammatory bowel diseases

AIM:To assess clinical and endoscopic response to propionyl-L-carnitine hydrochloride(PLC) in colonic inflammatory bowel disease.METHODS:Patients suffering from mild to moderate ulcerative colitis(UC) or Crohn's disease(CD) colitis,with disease activity index(DAI) between 3 and 10 and under stable therapy with oral aminosalicylates,mercaptopurine or azathioprine,for at least 8 wk prior to baseline assessments,were considered suitable for enrollment.Fourteen patients were enrolled to assume PLC 2 g/d(two active tablets twice daily) orally.Clinical-endoscopic and histological activity were assessed by DAI and histological index(HI),respectively,following a colonoscopy performed immediately before and after 4 wk treatment.Clinical response was defined as a lowering of at least 3 points in DAI and clinical remission as a DAI score ≤ 2.Histological response was defined as an improvement of HI of at least 1 point.We used median values for the analysis.Differences pre-and post-treatment were analyzed by Wilcoxon signed rank test.RESULTS:All patients enrolled completed the study.One patient,despite medical advice,took deflazacort 5 d before follow-up colonoscopy examination.No side effects were reported by patients during the trial.After treatment,71%(SE 12%) of patients achieved clinical response,while 64%(SE 13%) obtained remission.Separating UC from CD patients,we observed a clinical response in 60%(SE 16%) and 100%,respectively.Furthermore 60%(SE 16%) of UC patients and 75%(SE 25%) of CD patients were in clinical remission after therapy.The median DAI was 7 [interquartile range(IQR):4-8] before treatment and decreased to 2(IQR:1-3)(P < 0.01) after treatment.Only patients with UC showed a significant reduction of DAI,from a median 6.5(IQR:4-9) before treatment to 2(IQR:1-3) after treatment(P < 0.01).Conversely,in CD patients,although displaying a clear reduction of DAI from 7(IQR:5.5-7.5) before therapy to 1.5(IQR:0.5-2.5) after therapy,differences observed were not significant(P = 0.06).Seventy-nine percent(SE 11%) of patients showed improvement of HI of at least 1 point,while only one CD and two UC patients showed HI stability;none showed HI worsening.Median HI decreased from 1(IQR:1-2),to 0.5(IQR:0-1) at the endoscopic control in the whole population(P < 0.01),while it changed from 1(IQR:1-2) to 0.5(IQR:0-1) in UC patients(P < 0.01) and from 1.5(IQR:1-2) to 0.5(IQR:0-1) in CD patients(P = not significant).The two sample tests of proportions showed no significant differences in clinical and histological response or in clinical remission between UC and CD patients.No side effects were reported during treatment or at 4 wk follow-up visit.CONCLUSION:PLC improves endoscopic and histological activity of mild to moderate UC.Further studies are required to evaluate PLC efficacy in colonic CD patients.

Infliximab does not increase colonic cancer risk associated to murine chronic colitis

AIM To explore the influence of Infliximab(IFX) on cancer progression in a murine model of colonic cancer associated to chronic colitis.METHODS AOM/DSS model was induced in C57BL/6 mice. Mice were injected with IFX(5 mg/kg) during each DSS cycle while control mice received saline. Body weight, occult blood test and stool consistency were measured to calculate the disease activity index(DAI). Mice were sacrificed at week 10 and colons were analyzed macroscopically and microscopically for number of cancers and degree of inflammation. MTT assay was performed on CT26 to evaluate the potential IFX role on metabolic activity and proliferation. Cells were incubated with TNF-α or IFX or TNF-α plus IFX, and cell vitality was evaluated after 6, 24 and 48 h. The same setting was used after pre-incubation with TNF-α for 24 h.RESULTS IFX significantly reduced DAI and body weight loss in mice compared with controls, preserving also colon length at sacrifice. Histological score was also reduced in treated mice. At macroscopic analysis, IFX treated mice showed a lower number of tumor lesions compared to controls. This was confirmed at microscopic analysis, although differences were not statistically significant. In vitro, IFX treated CT26 maintained similar proliferation ability at MTT test, both when exposed to IFX alone and when associated to TNF-α.CONCLUSION IFX did not increase colonic cancer risk in AOM-DSS model of cancer on chronic colitis nor influence directly the proliferation of murine colon cancer epithelial cells.