Apc-mutant cells act as supercompetitors in intestinal tumour initiation.

A delicate equilibrium of WNT agonists and antagonists in the intestinal stem cell (ISC) niche is critical to maintaining the ISC compartment, as it accommodates the rapid renewal of the gut lining. Disruption of this balance by mutations in the tumour suppressor gene APC, which are found in approximately 80% of all human colon cancers, leads to unrestrained activation of the WNT pathway1,2. It has previously been established that Apc-mutant cells have a competitive advantage over wild-type ISCs3. Consequently, Apc-mutant ISCs frequently outcompete all wild-type stem cells within a crypt, thereby reaching clonal fixation in the tissue and initiating cancer formation. However, whether the increased relative fitness of Apc-mutant ISCs involves only cell-intrinsic features or whether Apc mutants are actively involved in the elimination of their wild-type neighbours remains unresolved. Here we show that Apc-mutant ISCs function as bona fide supercompetitors by secreting WNT antagonists, thereby inducing differentiation of neighbouring wild-type ISCs. Lithium chloride prevented the expansion of Apc-mutant clones and the formation of adenomas by rendering wild-type ISCs insensitive to WNT antagonists through downstream activation of WNT by inhibition of GSK3ß. Our work suggests that boosting the fitness of healthy cells to limit the expansion of pre-malignant clones may be a powerful strategy to limit the formation of cancers in high-risk individuals.

Spatiotemporal regulation of clonogenicity in colorectal cancer xenografts.

Cancer evolution is predominantly studied by focusing on differences in the genetic characteristics of malignant cells within tumors. However, the spatiotemporal dynamics of clonal outgrowth that underlie evolutionary trajectories remain largely unresolved. Here, we sought to unravel the clonal dynamics of colorectal cancer (CRC) expansion in space and time by using a color-based clonal tracing method. This method involves lentiviral red-green-blue (RGB) marking of cell populations, which enabled us to track individual cells and their clonal outgrowth during tumor initiation and growth in a xenograft model. We found that clonal expansion largely depends on the location of a clone, as small clones reside in the center and large clones mostly drive tumor growth at the border. These dynamics are recapitulated in a computational model, which confirms that the clone position within a tumor rather than cell-intrinsic features, is crucial for clonal outgrowth. We also found that no significant clonal loss occurs during tumor growth and clonal dispersal is limited in most models. Our results imply that, in addition to molecular features of clones such as (epi-)genetic differences between cells, clone location and the geometry of tumor growth are crucial for clonal expansion. Our findings suggest that either microenvironmental signals on the tumor border or differences in physical properties within the tumor, are major contributors to explain heterogeneous clonal expansion. Thus, this study provides further insights into the dynamics of solid tumor growth and progression, as well as the origins of tumor cell heterogeneity in a relevant model system.

A mouse model for peritoneal metastases of colorectal origin recapitulates patient heterogeneity.

The peritoneum is a common site of dissemination in patients with colorectal cancer. In order to identify high-risk patients and improve therapeutic strategies, a better understanding of the peritoneal dissemination process and the reasons behind the high heterogeneity that is observed between patients is required. We aimed to create a murine model to further elucidate the process of peritoneal dissemination and to provide an experimental platform for further studies. We developed an in vivo model to assess patterns of peritoneal dissemination of 15 colorectal cancer cell lines. Immune deficient mice were intraperitoneally injected with 10,000 human colorectal cancer cells. Ten weeks after injection, or earlier in case of severe discomfort, the mice were sacrificed followed by dissection including assessment of the outgrowth and localization of peritoneal metastases. Furthermore, using a color-based clonal tracing method, the clonal dynamics of peritoneal nodules were observed. The different cell lines showed great variation in the extent of peritoneal outgrowth, ranging from no outgrowth to localized or widespread outgrowth of cells. An association between KRAS pathway activation and the formation of peritoneal metastases was identified. Also, cell line specific tumor location preferences were observed, with similar patterns of outgrowth in anatomically related areas. Furthermore, different patterns regarding clonal dynamics were found, varying from monoclonal or polyclonal outgrowth to extensively dispersed polyclonal lesions. The established murine model recapitulates heterogeneity as observed in human peritoneal metastases, which makes it a suitable platform for future (intervention) studies.

Could an Innovative Training Program Including Contact Sports and Counseling Help Young People With Traits of Psychopathy and A History of School Dropout?

BACKGROUND: The aim was to assess the effects of a training program inclusive of contact sports and counseling on school dropout, quality of life (QoL) and psychopathologic symptoms in the youth with a history of school dropout and psychopathic personality traits. METHODS: The Experimental Group (EG) consisted of 32 subjects (male 90.6%; age 19.6±4.3 years); the Control Group (CG) consisted of an equal number matched for gender and age with the same psychological features. At the beginning of the experimental Training Program (T0), both cohorts were assessed by a diagnostic psychiatric interview (SCID ANTAS), the Short Form Health Survey (SF-12) to evaluate QoL, the Psychopathy Checklist - Revised (PCL-R) for the assessment of psychopathic traits, the Self Reporting Questionnaire (SRQ) to measure general psychopathology. At the end of the program (T1), the coorths were evaluated by SF-12 and SRQ. RESULTS: Twenty-seven subjects in the EG (84.4%) completed the course and underwent the evaluation at T1. The SF-12 score significantly increased from T0 to T1 in both groups, albeit this was more evident in the EG than in the CG, owing to an interaction between time and group. SRQ score significantly decreased in the EG from T0 to T1, while in the CG it did not, although the interaction between time and group was not significant. CONCLUSION: The experimental training program was effective in improving QoL and countering school dropout in young citizens with psychopathic traits. Further studies are needed to clarify if such results are due to a relationship between the practical tasks approach including contact sports and an improvement in mentalization processes.

Exome analysis in 34 sudden unexplained death (SUD) victims mainly identified variants in channelopathy-associated genes.

Sudden cardiac death (SCD) is one of the major causes of mortality worldwide, mostly involving coronary artery disease in the elderly. In contrary, sudden death events in young victims often represent the first manifestation of undetected genetic cardiac diseases, which remained without any symptoms during lifetime. Approximately 30% of these sudden death cases have no definite cardiac etiology after a comprehensive medicolegal investigation and are therefore termed as sudden unexplained death (SUD) cases. Advances in high-throughput sequencing approaches have provided an efficient diagnostic tool to identify likely pathogenic variants in cardiovascular disease-associated genes in otherwise autopsy-negative SUD cases. The aim of this study was to genetically investigate a cohort of 34 unexplained death cases by focusing on candidate genes associated with cardiomyopathies and channelopathies. Exome analysis identified potentially disease-causing sequence alterations in 29.4% of the 34 SUD cases. Six (17.6%) individuals had variants with likely functional effects in the channelopathy-associated genes AKAP9, KCNE5, RYR2, and SEMA3A. Interestingly, four of these six SUD individuals were younger than 18 years of age. Since the total SUD cohort of this study included five children and adolescents, post-mortem molecular autopsy screening indicates a high diagnostic yield within this age group. Molecular genetic testing represents a valuable approach to uncover the cause of death in some of the SUD victims; however, 70-80% of the cases still remain elusive, emphasizing the importance of additional research to better understand the pathological mechanisms leading to a sudden death event.

Field Trial and Molecular Characterization of RNAi-Transgenic Tomato Plants That Exhibit Resistance to Tomato Yellow Leaf Curl Geminivirus.

RNA interference (RNAi) is a widely used approach to generate virus-resistant transgenic crops. However, issues of agricultural importance like the long-term durability of RNAi-mediated resistance under field conditions and the potential side effects provoked in the plant by the stable RNAi expression remain poorly investigated. Here, we performed field trials and molecular characterization studies of two homozygous transgenic tomato lines, with different selection markers, expressing an intron-hairpin RNA cognate to the Tomato yellow leaf curl virus (TYLCV) C1 gene. The tested F6 and F4 progenies of the respective kanamycin- and basta-resistant plants exhibited unchanged field resistance to TYLCV and stably expressed the transgene-derived short interfering RNA (siRNAs) to represent 6 to 8% of the total plant small RNAs. This value outnumbered the average percentage of viral siRNAs in the nontransformed plants exposed to TYLCV-infested whiteflies. As a result of the RNAi transgene expression, a common set of up- and downregulated genes was revealed in the transcriptome profile of the plants selected from either of the two transgenic events. A previously unidentified geminivirus causing no symptoms of viral disease was detected in some of the transgenic plants. The novel virus acquired V1 and V2 genes from TYLCV and C1, C2, C3, and C4 genes from a distantly related geminivirus and, thereby, it could evade the repressive sequence-specific action of transgene-derived siRNAs. Our findings shed light on the mechanisms of siRNA-directed antiviral silencing in transgenic plants and highlight the applicability limitations of this technology as it may alter the transcriptional pattern of nontarget genes.

Full-length haplotype reconstruction to infer the structure of heterogeneous virus populations.

Next-generation sequencing (NGS) technologies enable new insights into the diversity of virus populations within their hosts. Diversity estimation is currently restricted to single-nucleotide variants or to local fragments of no more than a few hundred nucleotides defined by the length of sequence reads. To study complex heterogeneous virus populations comprehensively, novel methods are required that allow for complete reconstruction of the individual viral haplotypes. Here, we show that assembly of whole viral genomes of ∼8600 nucleotides length is feasible from mixtures of heterogeneous HIV-1 strains derived from defined combinations of cloned virus strains and from clinical samples of an HIV-1 superinfected individual. Haplotype reconstruction was achieved using optimized experimental protocols and computational methods for amplification, sequencing and assembly. We comparatively assessed the performance of the three NGS platforms 454 Life Sciences/Roche, Illumina and Pacific Biosciences for this task. Our results prove and delineate the feasibility of NGS-based full-length viral haplotype reconstruction and provide new tools for studying evolution and pathogenesis of viruses.

Quality of Life in Carotid Atherosclerosis: The Role of Co-morbid Mood Disorders.

INTRODUCTION/OBJECTIVE: To study in severe carotid atherosclerosis (CA): the frequency of mood disorders (MD); the impairment of quality of life (QoL); the role of co-morbid MD in such impairment. METHODS: Case-control study. CASES: consecutive in-patients with CA (stenosis ≥ 50%). CONTROLS: subjects with no diagnosis of CA randomized from a database of a community survey. Psychiatric diagnosis according to DSM-IV made by clinicians and semi-structured interview, QoL measured by the Short Form Health Survey (SF-12). RESULTS: This is the first study on comorbidity on CA disease and MD in which psychiatric diagnoses are conducted by clinicians according to DSM-IV diagnostic criteria. Major Depressive Disorder (MDD) (17.4% vs 2.72%, P <0.0001) but not Bipolar Disorders (BD) (4.3% vs 0.5%, P = 0.99) was higher in cases (N=46) than in controls (N= 184). SF-12 scores in cases were lower than in controls (30.56±8.12 vs 36.81±6:40; p <0.001) with QoL comparable to serious chronic diseases of the central nervous system. The burden of a concomitant MDD or BD amplifies QoL impairment. CONCLUSION: Comorbid MD aggravates the impairment of QoL in CA. Unlike autoimmune diseases or degenerative diseases of the Central Nervous System, CA shows a strong risk of MDD than BD.

Patients with carotid atherosclerosis who underwent or did not undergo carotid endarterectomy: outcome on mood, cognition and quality of life.

BACKGROUND: To compare the six-month outcome on mood, cognition and quality of life (QoL) in patients with severe carotid atherosclerosis (CA) who underwent carotid endarterectomy (CEA) with subjects who refused treatment. METHODS: Cohort study on consecutive inpatients with CA (stenosis ≥ 50 %) (N = 46; age 72.56 ± 7.26; male 65.2 %). Intervention cohort: subjects who decided to undergo CEA (N = 35); Control cohort patients who refused CEA (N = 11). DSM-IV-Psychiatric diagnosis made by clinicians using interviews, QoL measured by Short Form Health Survey (SF-12); cognitive performance by WAIS Intelligent Coefficient (IC). RESULTS: The study showed a better improvement during six months in Overall IC, Performance IC and Verbal IC in the group that underwent CEA. QoL in the two cohorts did not reach statistical significance. Percentages of patients who improved in the CEA group were significantly higher with regard to Overall and Verbal IC scores, and at the limits of statistical significance in Performance IC. The differences of subject with improvement in SF-12 score in the two groups did not reach statistical significance. Ages below 68 were found to be determinant of a good outcome in Overall IC score. Limit: study conducted with a small sample size. CONCLUSIONS: Patients with severe carotid atherosclerosis who underwent CEA enhanced their cognitive performance.

Misdiagnosed hypomanic symptoms in patients with treatment-resistant major depressive disorder in Italy: results from the improve study.

BACKGROUND: Undiagnosed and therefore inadequately treated hypomanic symptoms may be a leading cause of drug resistance in depression diagnosed as unipolar (major depressive disorder, MDD). The purpose of the IMPROVE study was to identify the rate of misdiagnoses in patients with treatment-resistant MDD by screening for the presence of previous hypomanic episodes, and to study the characteristics of those patients with a positive history of hypomania. METHODS: Patients attending 29 psychiatric units throughout Italy with a diagnosis of MDD who were resistant to anti-depressant treatment were included in this multicentre, observational single visit study. The Hypomania Checklist 32 (HCL-32) was administered to detect underlying bipolarity. RESULTS: Among the 466 enrolled patients, 256 (57.40%) were positive at screening for a previous hypomanic episode (HCL-32 ≥12), therefore suggesting a misdiagnosis. These patients scored higher than those with a negative history in both the "active/elated hypomania" (11.27±3.11 vs 3.57±3.05; P<0.0001) and "irritable/risk-taking hypomania" (2.87±2.03 vs 2.06±1.73; P<0.001) HCL-32 sub-scales. Patients with a positive history of hypomania were younger, had a higher number of previous depressive episodes and a higher frequency of comorbid conditions compared to those with a negative history. CONCLUSIONS: This study suggests that screening for hypomania in MDD-resistant patients facilitates identification of a notable proportion of undiagnosed cases of bipolar spectrum disorder. Patients with a positive history of hypomania at screening had a demographic/clinical bipolar-like profile that included young age, higher number of previous depressive episodes and higher frequency of comorbid conditions. They also had both higher active and irritable hypomania symptom scores.

Quality of life and urban / rural living: preliminary results of a community survey in Italy.

BACKGROUND: The purpose of this population-based study is to examine the association between subjective quality of life and rural/urban residence in six Italian regions, including age and gender into the analysis. STUDY DESIGN: community survey. STUDY POPULATION: Samples stratified according to sex and age, drawn from municipal records. SAMPLE SIZE: 4999 people 18 years and older, from seven communities within six regions of Italy. TOOLS: Ad-hoc form to assess basic demographic data; SF-12. Interviewers were trained psychologists or medical doctors. RESULTS: 3398 subjects were interviewed (68% of recruited sample). The mean score of SF-12 in the overall sample was 38.4±6.1, SF-12 was higher in men than in in women (38.4±6.1 vs 37.5±5.9 F=99.18, df 1, 3396, 3397, p<0.0001); SF-12 score decreased from the youngest to the oldest age group, with significant differences between all ages groups; men showed higher scores in all age groups. The urban/rural difference of mean scores of SF-12 did not achieve statistical significance in women. Young men with urban residence had higher SF-12 scores than their counterparts with rural residence. Maen aged 65 years and older with rural residence showed, by contrast, higher scores than men from the same age group with urban residence. CONCLUSIONS: Men show a higher subjective quality of life than women. Subjective quality of life decreases with age in both genders.Men are more sensitive to urban/rural residence than women.Young men live better in cities, elderly men better in rural areas.

Molecular characterization of colorectal cancer related peritoneal metastatic disease.

A significant proportion of colorectal cancer (CRC) patients develop peritoneal metastases (PM) in the course of their disease. PMs are associated with a poor quality of life, significant morbidity and dismal disease outcome. To improve care for this patient group, a better understanding of the molecular characteristics of CRC-PM is required. Here we present a comprehensive molecular characterization of a cohort of 52 patients. This reveals that CRC-PM represent a distinct CRC molecular subtype, CMS4, but can be further divided in three separate categories, each presenting with unique features. We uncover that the CMS4-associated structural protein Moesin plays a key role in peritoneal dissemination. Finally, we define specific evolutionary features of CRC-PM which indicate that polyclonal metastatic seeding underlies these lesions. Together our results suggest that CRC-PM should be perceived as a distinct disease entity.

Sub-threshold depression and antidepressants use in a community sample: searching anxiety and finding bipolar disorder.

BACKGROUND: To determine the use of antidepressants (ADs) in people with sub-threshold depression (SD); the lifetime prevalence of mania and hypomania in SD and the link between ADs use, bipolarity and anxiety disorders in SD. STUDY DESIGN: community survey. STUDY POPULATION: samples randomly drawn, after stratification from the adult population of municipal records. SAMPLE SIZE: 4999 people from seven areas within six Italian regions. Tools: Questionnaire on psychotropic drug consumption, prescription; Structured Clinical Interview NP for DSM-IV modified (ANTAS); Hamilton Depression Rating Scale (HAM-D); Mood Disorder Questionnaire (MDQ); Short Form Health Survey (SF-12). SD definition: HAM-D > 10 without lifetime diagnosis of Depressive Episode (DE). RESULTS: SD point prevalence is 5.0%. The lifetime prevalence of mania and hypomania episodes in SD is 7.3%. Benzodiazepines (BDZ) consumption in SD is 24.1%, followed by ADs (19.7%). In SD, positive for MDQ and comorbidity with Panic Disorder (PD) or Generalized Anxiety Disorders (GAD) are associated with ADs use, whereas the association between a positive MDQ and ADs use, without a diagnosis of PD or GAD, is not significant. Only in people with DE the well-being (SF-12) is higher among those using first-line antidepressants compared to those not using any medication. In people with SD no significant differences were found in terms of SF-12 score according to drug use. CONCLUSIONS: This study suggests caution in prescribing ADs to people with SD. In people with concomitant anxiety disorders and SD, it should be mandatory to perform a well-designed assessment and evaluate the presence of previous manic or hypomanic symptoms prior to prescribing ADs.

Benefits of exercise with mini tennis in intellectual disabilities: effects on body image and psychopathology.

The present study is aimed at evaluating the efficacy of an introductory mini tennis programme as a therapeutic aid in the psychosocial rehabilitation of participants affected by mild/moderate intellectual disability in semi-residential care.Two groups (N=12) of participants diagnosed with intellectual disability, one of which followed the mini tennis rehabilitation programme, were compared at time t0, t1 (after 2 months) and t2 (after 6 months).Psychopathological status was assessed by means of the Italian version of the Assessment and Information Rating Profile (AIRP). Motor coordination, lateral dominance and body scheme were assessed by means of structured tools.Psychopathological total scores showed a statistically significant decrease in the experimental group in comparison with the control group. A statistical decrease in the group with the mini tennis rehabilitation programme was found also in the anxiety sub-scale while the sub-scales schizophrenia, depression, adjustment disorder, personality problems, somatoform disorders and psychosexual disorders did not reach any statistical difference between groups.A statistically significant increase in the visuo manual coordination was highlighted in the experimental versus the control group. No statistically significant differences were reported with regard to general movement skills, dynamic balance and coordination.In spite of the limitations of this study, the results obtained are encouraging and suggest the potential efficacy of mini tennis as an auxiliary aid in rehabilitation programmes, particularly to improve visuo manual coordination skills and to boost the patient/participants' self esteem. These findings warrant confirmation by further research studies.

Marker-free lineage tracing reveals an environment-instructed clonogenic hierarchy in pancreatic cancer.

Effective treatments for pancreatic ductal adenocarcinoma (PDAC) are lacking, and targeted agents have demonstrated limited efficacy. It has been speculated that a rare population of cancer stem cells (CSCs) drives growth, therapy resistance, and rapid metastatic progression in PDAC. These CSCs demonstrate high clonogenicity in vitro and tumorigenic potential in vivo. However, their relevance in established PDAC tissue has not been determined. Here, we use marker-independent stochastic clonal labeling, combined with quantitative modeling of tumor expansion, to uncover PDAC tissue growth dynamics. We find that in contrast to the CSC model, all PDAC cells display clonogenic potential in situ. Furthermore, the proximity to activated cancer-associated fibroblasts determines tumor cell clonogenicity. This means that the microenvironment is dominant in defining the clonogenic activity of PDAC cells. Indeed, manipulating the stroma by Hedgehog pathway inhibition alters the tumor growth mode, revealing that tumor-stroma crosstalk shapes tumor growth dynamics and clonal architecture.

Continuous clonal labeling reveals uniform progenitor potential in the adult exocrine pancreas.

The tissue dynamics that govern maintenance and regeneration of the pancreas remain largely unknown. In particular, the presence and nature of a cellular hierarchy remains a topic of debate. Previous lineage tracing strategies in the pancreas relied on specific marker genes for clonal labeling, which left other populations untested and failed to account for potential widespread phenotypical plasticity. Here we employed a tracing system that depends on replication-induced clonal marks. We found that, in homeostasis, steady acinar replacement events characterize tissue dynamics, to which all acinar cells have an equal ability to contribute. Similarly, regeneration following pancreatitis was best characterized by an acinar self-replication model because no evidence of a cellular hierarchy was detected. In particular, rapid regeneration in the pancreas was found to be driven by an accelerated rate of acinar fission-like events. These results provide a comprehensive and quantitative model of cell dynamics in the exocrine pancreas.

Phenylbutyrate up-regulates the adrenoleukodystrophy-related gene as a nonclassical peroxisome proliferator.

X-linked adrenoleukodystrophy (X-ALD) is a demyelinating disease due to mutations in the ABCD1 (ALD) gene, encoding a peroxisomal ATP-binding cassette transporter (ALDP). Overexpression of adrenoleukodystrophy-related protein, an ALDP homologue encoded by the ABCD2 (adrenoleukodystrophy-related) gene, can compensate for ALDP deficiency. 4-Phenylbutyrate (PBA) has been shown to induce both ABCD2 expression and peroxisome proliferation in human fibroblasts. We show that peroxisome proliferation with unusual shapes and clusters occurred in liver of PBA-treated rodents in a PPARalpha-independent way. PBA activated Abcd2 in cultured glial cells, making PBA a candidate drug for therapy of X-ALD. The Abcd2 induction observed was partially PPARalpha independent in hepatocytes and totally independent in fibroblasts. We demonstrate that a GC box and a CCAAT box of the Abcd2 promoter are the key elements of the PBA-dependent Abcd2 induction, histone deacetylase (HDAC)1 being recruited by the GC box. Thus, PBA is a nonclassical peroxisome proliferator inducing pleiotropic effects, including effects at the peroxisomal level mainly through HDAC inhibition.

The use of antidepressant drugs and the lifetime prevalence of major depressive disorders in Italy.

BACKGROUND: The increased use of antidepressant drugs (ADs) improved the response to the needs of care although some community surveys have shown that subjects without lifetime psychiatric diagnosis (anxiety/depression) used ADs. OBJECTIVES: To evaluate the appropriateness and amount of prescription of psychotropic drugs in people with lifetime diagnosis of Major Depressive Disorder (MDD) by means of community survey with a semi-structured interview as a diagnostic instrument, administered by clinicians. STUDY DESIGN: community survey. STUDY POPULATION: samples randomly drawn, after stratification from the adult population of municipal records. SAMPLE SIZE: 4.999 people were drawn in 7 centres of 6 Italian regions. TOOLS: questionnaire on psychotropic drug consumption, prescription, health services utilization; Structured Clinical Interview for DSM-IV modified (ANTAS); Training: interviewers were trained psychologists or medical doctors. RESULTS: 3.398 subjects were interviewed (68% of the recruited sample). The lifetime prevalence of DSM-IV MDD was 4.3% in males and 11.5% in females; antidepressant drugs were taken by 4.7% of subjects, 2.9% male and 5.9% female. 38% of males and 57% of females with lifetime diagnosis of MDD were taking ADs. CONCLUSIONS: Compared with studies using lay interviewers and structured tools the prevalence of the MDD was quite lower; ADs use was higher and tallied well with the data regarding antidepressant sales in Italy; the correspondence between lifetime diagnosis of MDD and ADs use was closer.

A cancer drug atlas enables synergistic targeting of independent drug vulnerabilities.

Personalized cancer treatments using combinations of drugs with a synergistic effect is attractive but proves to be highly challenging. Here we present an approach to uncover the efficacy of drug combinations based on the analysis of mono-drug effects. For this we used dose-response data from pharmacogenomic encyclopedias and represent these as a drug atlas. The drug atlas represents the relations between drug effects and allows to identify independent processes for which the tumor might be particularly vulnerable when attacked by two drugs. Our approach enables the prediction of combination-therapy which can be linked to tumor-driving mutations. By using this strategy, we can uncover potential effective drug combinations on a pan-cancer scale. Predicted synergies are provided and have been validated in glioblastoma, breast cancer, melanoma and leukemia mouse-models, resulting in therapeutic synergy in 75% of the tested models. This indicates that we can accurately predict effective drug combinations with translational value.

Stem cell functionality is microenvironmentally defined during tumour expansion and therapy response in colon cancer.

Solid malignancies have been speculated to depend on cancer stem cells (CSCs) for expansion and relapse after therapy. Here we report on quantitative analyses of lineage tracing data from primary colon cancer xenograft tissue to assess CSC functionality in a human solid malignancy. The temporally obtained clone size distribution data support a model in which stem cell function in established cancers is not intrinsically, but is entirely spatiotemporally orchestrated. Functional stem cells that drive tumour expansion predominantly reside at the tumour edge, close to cancer-associated fibroblasts. Hence, stem cell properties change in time depending on the cell location. Furthermore, although chemotherapy enriches for cells with a CSC phenotype, in this context functional stem cell properties are also fully defined by the microenvironment. To conclude, we identified osteopontin as a key cancer-associated fibroblast-produced factor that drives in situ clonogenicity in colon cancer.