Unsupervised Feature Selection by a Genetic Algorithm for Mid-Infrared Spectral Data.

Dimensional reduction of highly multidimensional datasets such as those acquired by Fourier transform infrared spectroscopy (FTIR) is a critical step in the data analysis workflow. To achieve this goal, numerous feature selection methods have been developed and applied in a supervised context, i.e., using a priori knowledge about data usually in the form of labels for classification or quantitative values for regression. For this, genetic algorithms have been largely exploited due to their flexibility and global optimization principle. However, few applications in an unsupervised context have been reported in infrared spectroscopy. The aim of this article is to propose a new unsupervised feature selection method based on a genetic algorithm using a validity index computed from KMeans partitions as a fitness function. Evaluated on a simulated dataset and validated and tested on three real-world infrared spectroscopic datasets, our developed algorithm is able to find the spectral descriptors improving clustering accuracy and simplifying the spectral interpretation of results.

Automatic Identification of Paraffin Pixels on FTIR Images Acquired on FFPE Human Samples.

The transfer of mid-infrared spectral histopathology to the clinic will be possible provided that its application in clinical practice is simple. Rapid analysis of formalin-fixed paraffin-embedded (FFPE) tissue section is thus a prerequisite. The chemical dewaxing of these samples before image acquisition used by the majority of studies is in contradiction with this principle. Fortunately, the in silico analysis of the images acquired on FFPE samples is possible using extended multiplicative signal correction (EMSC). However, the removal of pure paraffin pixels is essential to perform a relevant classification of tissue spectra. So far, this task was possible only if using manual and subjective histogram analysis. In this article, we thus propose a new automatic and multivariate methodology based on the analysis of optimized combinations of EMSC regression coefficients by validity indices and KMeans clustering to separate paraffin and tissue pixels. The validation of our method is performed using simulated infrared spectral images by measuring the Jaccard index between our partitions and the image model, with values always over 0.90 for diverse baseline complexity and signal-to-noise ratio. These encouraging results were also validated on real images by comparing our method with classical ones and by computing the Jaccard index between our partitions and the KMeans partitions obtained on the infrared image acquired on the same samples but after chemical dewaxing, with values always over 0.84.

Laminin α1 orchestrates VEGFA functions in the ecosystem of colorectal carcinoma.

BACKGROUND INFORMATION: Tumor stroma remodeling is a key feature of malignant tumors and can promote cancer progression. Laminins are major constituents of basement membranes that physically separate the epithelium from the underlying stroma. RESULTS: By employing mouse models expressing high and low levels of the laminin α1 chain (LMα1), we highlighted its implication in a tumor-stroma crosstalk, thus leading to increased colon tumor incidence, angiogenesis and tumor growth. The underlying mechanism involves attraction of carcinoma-associated fibroblasts by LMα1, VEGFA expression triggered by the complex integrin α2ß1-CXCR4 and binding of VEGFA to LM-111, which in turn promotes angiogenesis, tumor cell survival and proliferation. A gene signature comprising LAMA1, ITGB1, ITGA2, CXCR4 and VEGFA has negative predictive value in colon cancer. CONCLUSIONS: Together, we have identified VEGFA, CXCR4 and α2ß1 integrin downstream of LMα1 in colon cancer as of bad prognostic value for patient survival. SIGNIFICANCE: This information opens novel opportunities for diagnosis and treatment of colon cancer.

Development of a memetic clustering algorithm for optimal spectral histology: application to FTIR images of normal human colon.

The coupling between Fourier-transform infrared (FTIR) imaging and unsupervised classification is effective in revealing the different structures of human tissues based on their specific biomolecular IR signatures; thus the spectral histology of the studied samples is achieved. However, the most widely applied clustering methods in spectral histology are local search algorithms, which converge to a local optimum, depending on initialization. Multiple runs of the techniques estimate multiple different solutions. Here, we propose a memetic algorithm, based on a genetic algorithm and a k-means clustering refinement, to perform optimal clustering. In addition, this approach was applied to the acquired FTIR images of normal human colon tissues originating from five patients. The results show the efficiency of the proposed memetic algorithm to achieve the optimal spectral histology of these samples, contrary to k-means.

Impact of EGFR mutations and KRAS amino acid substitution on the response to radiotherapy for brain metastasis of non-small-cell lung cancer.

BACKGROUND: Our study aimed to evaluate response rate (RR) to brain metastasis radiotherapy (RT), depending on the genomic status of non-small-cell lung cancer. MATERIAL & METHODS: We retrospectively reviewed 1971 non-small-cell lung cancer files of patients with EGFR and KRAS testing and focused on 157 patients who had undergone RT for brain metastasis. RESULTS: A total of 16 patients (10.2%) harbored EGFR mutations (mEGFR) and 45 patients (28.7%) KRAS (mKRAS). In univariate analysis, RR was significantly higher for mEGFR compared with wild-type EGFR/KRAS (odds ratio [OR]: 4.96; p = 0.05) or mKRAS (OR: 1.81; p = 0.03). In multivariate analysis, KRAS G12V or G12C status was associated with both poor RR (OR: 0.1; p < 0.0001) and overall survival (OR: 3.41; p < 0.0001). CONCLUSION: mEGFR are associated with higher RR to brain RT than wild-type EGFR/RAS or mKRAS.

Prognostic value of the KRAS G12V mutation in 841 surgically resected Caucasian lung adenocarcinoma cases.

BACKGROUND: Identifying patients who will experience lung cancer recurrence after surgery remains a challenge. We aimed to evaluate whether mutant forms of epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma viral oncogene homolog (KRAS) (mEGFR and mKRAS) are useful biomarkers in resected non-small cell lung cancer (NSCLC). METHODS: We retrospectively reviewed data from 841 patients who underwent surgery and molecular testing for NSCLC between 2007 and 2012. RESULTS: mEGFR was observed in 103 patients (12.2%), and mKRAS in 265 (31.5%). The median overall survival (OS) and time to recurrence (TTR) were significantly lower for mKRAS (OS: 43 months; TTR: 19 months) compared with mEGFR (OS: 67 months; TTR: 24 months) and wild-type patients (OS: 55 months; disease-free survival (DFS): 24 months). Patients with KRAS G12V exhibited worse OS and TTR compared with the entire cohort (OS: KRAS G12V: 26 months vs COHORT: 60 months; DFS: KRAS G12V: 15 months vs COHORT: 24 months). These results were confirmed using multivariate analyses (non-G12V status, hazard ratio (HR): 0.43 (confidence interval: 0.28-0.65), P<0.0001 for OS; HR: 0.67 (0.48-0.92), P=0.01 for TTR). Risk of recurrence was significantly lower for non-KRAS G12V (HR: 0.01, (0.001-0.08), P<0.0001). CONCLUSIONS: mKRAS and mEGFR may predict survival and recurrence in early stages of NSCLC. Patients with KRAS G12V exhibited worse OS and higher recurrence incidences.

Development of a hierarchical double application of crisp cluster validity indices: a proof-of-concept study for automated FTIR spectral histology.

Fourier-transform infrared (FTIR) spectral imaging is currently used as a non-destructive and label-free method for analyzing biological specimens. However, to highlight the different tissue regions, unsupervised clustering methods are commonly used leading to a subjective choice of the number of clusters. Here, we develop a hierarchical double application of 9 selected crisp cluster validity indices (CCVIs) using K-Means clustering. This approach when tested first on an artificial dataset showed that the indices Pakhira-Bandyopadhyay-Maulik (PBM) and Sym-Index (SI) perfectly estimated the expected 9 sub-clusters. Then, the concept was applied to a real dataset consisting of FTIR spectral images of normal human colon tissue samples originating from 5 patients. PBM and SI were revealed to be the most efficient indices that correctly identified the different colon histological components including crypts, lamina propria, muscularis mucosae, submucosa, and lymphoid aggregates. In conclusion, these results strongly suggest that the hierarchical double CCVI application is a promising method for automated and informative spectral histology.

Hypoxia differentially regulated CXCR4 and CXCR7 signaling in colon cancer.

BACKGROUND: HIF-1α and CXCR4/CXCL12 have crucial roles in the metastatic process of colorectal cancer. Our aim was to study the significance of targeting HIF-1α and the CXCR4/CXCL12 axis in colorectal cancer to prevent the dissemination process in vitro. METHODS: We investigated CXCR4 and CXCR7 mRNA and protein expression in human colon carcinomas and the modulation of their expression by hypoxia and HIF-1α in colon cancer cell lines. The migration of tumor cells in a Boyden chamber was studied after CXCR4 inhibition with siRNA or the CXCR4/CXCL12 neutraligand, chalcone 4. RESULTS: Analysis of a cohort of colon polyps and chromosome-unstable carcinomas showed that the expression of CXCR4 and CXCR7 was similar to that of the normal mucosa in the polyps and early-stage carcinomas but significantly increased in late stage carcinomas. Our data demonstrate that hypoxia strongly induced the expression of CXCR4 transcript and protein at the cell membrane, both regulated by HIF-1α, whereas CXCR7 expression was independent of hypoxia. After transient hypoxia, CXCR4 levels remained stable at the cell membrane up to 48 hours. Furthermore, reducing CXCR4 expression impaired CXCL12-induced Akt phosphorylation, whereas Erk activation remained unchanged. In contrast, reducing CXCR7 expression did not affect Akt nor Erk activation. In the presence of CXCR4 or CXCR7 siRNAs, a significant reduction in cell migration occurred (37% and 17%, respectively). Although irinotecan inhibited cell migration by 20% (p <0.001), the irinotecan and chalcone 4 combination further increased inhibition to 40% (p <0.001). CONCLUSION: We demonstrated, for the first time, that hypoxia upregulated CXCR4 but not CXCR7 expression in tumor cells and that the CXCR4 receptor protein level remains high at the cell membrane when the tumor cells return to normoxia for up to 48 hours. In addition we showed the interest to inhibit the CXCR4 signaling by inhibiting both the HIF-1α and CXCR4/CXCL12 pathway. CXCR4 seems to be a relevant target because it is continuously expressed and functional both in normoxic and hypoxic conditions in tumor cells.

Molecular markers for recurrence and sensitivity to preoperative chemoradiotherapy in locally advanced rectal tumours.

BACKGROUND: The objective of our study is to provide predictive markers of locally advanced rectal tumour sensitivity to preoperative chemoradiotherapy in order to identify tumours that present a high risk of recurrence after standard total mesorectal excision surgery and preoperative chemoradiotherapy, according to histological response and microsatellite allelic imbalance (AI). METHODS: Twenty-nine locally advanced tumours were included in the study and the genomic alterations and the tumour regression grade of paired rectal biopsies (before chemoradiotherapy) and carcinomas (after surgery) were assessed. Clinical and allelotyping data were analysed for local and distant recurrence. RESULTS: The global AI frequency significantly decreased from 47.4 to 20.3% (p < 0.01) after preoperative treatment. Preoperative chemoradiotherapy significantly induced the loss of cells bearing AI at 8 microsatellites: D18S61, D8S264, D1S305, D10S191, D4S394, D14S65, D17S790 and D10S192. Among these, AI at the D8S264 locus was significantly associated with recurrence in our rectal tumour cohort (p = 0.039). CONCLUSION: Loss of AI at D8S264 is predictive of sensitivity to neoadjuvant treatment; thus, we concluded that the persistence of AI at D8S264 in rectal tumours after preoperative chemoradiotherapy could be considered a molecular marker of recurrence.

Gene expression classification of colon cancer into molecular subtypes: characterization, validation, and prognostic value.

BACKGROUND: Colon cancer (CC) pathological staging fails to accurately predict recurrence, and to date, no gene expression signature has proven reliable for prognosis stratification in clinical practice, perhaps because CC is a heterogeneous disease. The aim of this study was to establish a comprehensive molecular classification of CC based on mRNA expression profile analyses. METHODS AND FINDINGS: Fresh-frozen primary tumor samples from a large multicenter cohort of 750 patients with stage I to IV CC who underwent surgery between 1987 and 2007 in seven centers were characterized for common DNA alterations, including BRAF, KRAS, and TP53 mutations, CpG island methylator phenotype, mismatch repair status, and chromosomal instability status, and were screened with whole genome and transcriptome arrays. 566 samples fulfilled RNA quality requirements. Unsupervised consensus hierarchical clustering applied to gene expression data from a discovery subset of 443 CC samples identified six molecular subtypes. These subtypes were associated with distinct clinicopathological characteristics, molecular alterations, specific enrichments of supervised gene expression signatures (stem cell phenotype-like, normal-like, serrated CC phenotype-like), and deregulated signaling pathways. Based on their main biological characteristics, we distinguished a deficient mismatch repair subtype, a KRAS mutant subtype, a cancer stem cell subtype, and three chromosomal instability subtypes, including one associated with down-regulated immune pathways, one with up-regulation of the Wnt pathway, and one displaying a normal-like gene expression profile. The classification was validated in the remaining 123 samples plus an independent set of 1,058 CC samples, including eight public datasets. Furthermore, prognosis was analyzed in the subset of stage II-III CC samples. The subtypes C4 and C6, but not the subtypes C1, C2, C3, and C5, were independently associated with shorter relapse-free survival, even after adjusting for age, sex, stage, and the emerging prognostic classifier Oncotype DX Colon Cancer Assay recurrence score (hazard ratio 1.5, 95% CI 1.1-2.1, p = 0.0097). However, a limitation of this study is that information on tumor grade and number of nodes examined was not available. CONCLUSIONS: We describe the first, to our knowledge, robust transcriptome-based classification of CC that improves the current disease stratification based on clinicopathological variables and common DNA markers. The biological relevance of these subtypes is illustrated by significant differences in prognosis. This analysis provides possibilities for improving prognostic models and therapeutic strategies. In conclusion, we report a new classification of CC into six molecular subtypes that arise through distinct biological pathways.

Cdx2 controls expression of the protocadherin Mucdhl, an inhibitor of growth and ß-catenin activity in colon cancer cells.

BACKGROUND & AIMS: The intestine-specific homeobox transcription factor Cdx2 is an important determinant of intestinal identity in the embryonic endoderm and regulates the balance between proliferation and differentiation in the adult intestinal epithelium. Human colon tumors often lose Cdx2 expression, and heterozygous inactivation of Cdx2 in mice increases colon tumorigenesis. We sought to identify Cdx2 target genes to determine how it contributes to intestinal homeostasis. METHODS: We used expression profiling analysis to identify genes that are regulated by Cdx2 in colon cancer cells lines. Regulation and function of a potential target gene were further investigated using various cell assays. RESULTS: In colon cancer cell lines, Cdx2 directly regulated the transcription of the gene that encodes the protocadherin Mucdhl. Mucdhl localized to the apex of differentiated cells in the intestinal epithelium, and its expression was reduced in most human colon tumors. Overexpression of Mucdhl inhibited low-density proliferation of colon cancer cells and reduced tumor formation in nude mice. One isoform of Mucdhl interacted with ß-catenin and inhibited its transcriptional activity. CONCLUSIONS: The transcription factor Cdx2 activates expression of the protocadherin Mucdhl, which interacts with ß-catenin and regulates activities of intestinal cells. Loss of Cdx2 expression in colon cancer cells might reduce expression of Mucdhl and thereby lead to tumor formation.

Selective aminopeptidase-N (CD13) inhibitors with relevance to cancer chemotherapy.

Aminopeptidase-N (APN/CD13) is highly expressed on the surface of numerous types of cancer cells and particularly on the endothelial cells of neoangiogenic vessels during tumourigenesis. This metallo-aminopeptidase has been identified as a potential target for cancer chemotherapy. In this work, we evaluated the efficacy of a novel series of benzosuberone analogues, which were previously reported to be highly potent, selective APN inhibitors with Ki values in the micromolar to sub-nanomolar range. Endothelial cell morphogenesis as well as cell motility were inhibited in vitro in a dose-dependent manner at concentrations that correlated with the potency of the compounds, thus confirming the key role of APN in these established models of angiogenesis. We report toxicity studies in mice showing that these compounds are well tolerated. We report the effects of the compounds, used alone or in combination with rapamycin, on the growth of a select panel of tumours that were subcutaneously xenografted onto Swiss nude mice. Our data indicate that the in vivo efficacy of these new APN inhibitors during the initial phase of tumour growth can be ascribed to their anti-angiogenic activities. However, we also provide evidence that these compounds are effective against established solid tumours. For colonic tumours, the anti-tumour effect depends on the level of APN expression in epithelial cells, and APN expression is associated with down-regulation of the transcription factor HIF-1α. These effects seem to be distinct from those of rapamycin. Our finding that the anti-tumour effect of the inhibitors in the colon requires APN expression strongly suggests that APN plays a crucial function in tumour cells that is distinct from its known role in neovascularisation.

Involvement of the TGFß pathway in the regulation of α5 ß1 integrins by caveolin-1 in human glioblastoma.

Caveolin-1 plays a crucial role in the development of cancer and its progression. We previously reported that glioblastoma cells expressing low levels of caveolin-1 exerted a more aggressive phenotype than cells expressing high levels. Such phenotype was due to the induction of α(5) ß(1) integrin subsequent to the depletion of caveolin-1. Caveolin-1 was identified as a transcriptional repressor of α(5) ß(1) integrin. The current study was designed to identify in vitro, the molecular mechanisms by which caveolin-1 controls α(5) ß(1) integrin expression and to determine if a negative correlation between caveolin-1 and α(5) ß(1) integrins also exists in biopsies and xenografted human brain tumors. We showed that depletion of caveolin-1 lead to the activation of the TGFß/TGFßRI/Smad2 pathway which in turn induced the expression of α(5) ß(1) integrins. We showed that cells expressing the lowest levels of caveolin-1 but the highest levels of α(5) ß(1) integrins and TGFßRI were the most sensitive to a α(5) ß(1) integrin antagonist and a TGFßRI inhibitor. Screening human glioma biopsies and human glioblastoma xenografts, we isolated subgroups with either low levels of caveolin-1 but high levels of α(5) ß(1) integrin and TGFßRI or high levels of caveolin-1 but low levels of α(5) ß(1) integrin and TGFßRI. In conclusion, caveolin-1 controls α(5) ß(1) integrin expression through the TGFß/TGFßRI/Smad2 pathway. The status of caveolin-1/α(5) ß(1) integrins/TGFßRI might be a useful marker of the tumor evolution/prognosis as well as a predictor of anti-TGFß or anti-α(5) ß(1) integrin therapies.

In vivo topoisomerase I inhibition attenuates the expression of hypoxia-inducible factor 1α target genes and decreases tumor angiogenesis.

Topoisomerase I is a privileged target for widely used anticancer agents such as irinotecan. Although these drugs are classically considered to be DNA-damaging agents, increasing evidence suggests that they might also influence the tumor environment. This study evaluates in vivo cellular and molecular modifications induced by irinotecan, a topoisomerase I-directed agent, in patient-derived colon tumors subcutaneously implanted in athymic nude mice. Irinotecan was given intraperitoneally at 40 mg/kg five times every 5 d, and expression profiles were evaluated at d 25 in tumors from treated and untreated animals. Unexpectedly, the in vivo antitumor activity of irinotecan was closely linked to a downregulation of hypoxia-inducible factor-1α (HIF1A) target genes along with an inhibition of HIF1A protein accumulation. The consequence was a decrease in tumor angiogenesis leading to tumor size stabilization. These results highlight the molecular basis for the antitumor activity of a widely used anticancer agent, and the method used opens the way for mechanistic studies of the in vivo activity of other anticancer therapies.

Colorectal Cancer: The Contribution of CXCL12 and Its Receptors CXCR4 and CXCR7.

Colorectal cancer is one of the most common cancers, and diagnosis at late metastatic stages is the main cause of death related to this cancer. This progression to metastasis is complex and involves different molecules such as the chemokine CXCL12 and its two receptors CXCR4 and CXCR7. The high expression of receptors in CRC is often associated with a poor prognosis and aggressiveness of the tumor. The interaction of CXCL12 and its receptors activates signaling pathways that induce chemotaxis, proliferation, migration, and cell invasion. To this end, receptor inhibitors were developed, and their use in preclinical and clinical studies is ongoing. This review provides an overview of studies involving CXCR4 and CXCR7 in CRC with an update on their targeting in anti-cancer therapies.

Allelotyping identification of genomic alterations in rectal chromosomally unstable tumors without preoperative treatment.

BACKGROUND: Numerous studies reported genomic alterations in colorectal human tumors but few focused on rectal tumors with the specification of preoperative-treated or untreated tumors. The goals of this study were to list chromosome allelic imbalances and correlate their frequency with tumor progression and to identify potential molecular markers of progression in rectal chromosomally unstable tumors without preoperative treatment. METHODS: Genomic alterations of 57 rectal tumors assessed by allelotyping targeting 33 chromosomal loci, were clusterised and compared to those of 151 left colon tumors. RESULTS: Clustering separated the rectal tumors without preoperative treatment into three subtypes according to the allelic imbalance frequency and genomic alteration associations. The tumors without preoperative treatment displayed a significantly higher allelic imbalance frequency (54%) than the tumors with preoperative treatment (33%), suggesting that treatment could target highly altered tumor clones. Interestingly, the survival analysis identified three potential prognostic molecular survival markers, D1S197, D5S430, and D14S65, for tumors without preoperative treatment. CONCLUSION: Based on the genomic status of 33 chromosomal loci, we observed that rectal tumors without preoperative treatment segregate according to the global allelic imbalance frequency but without correlation to the tumor progression. Moreover, the detailed associations of alterations in rectal tumors are different from those described in colon tumors suggesting that rectal and left tumors should be considered as separate entities. Finally, potential prognostic genomic molecular markers for survival are proposed which status could specify the clinical course of the tumors.

Marked activity of irinotecan and rapamycin combination toward colon cancer cells in vivo and in vitro is mediated through cooperative modulation of the mammalian target of rapamycin/hypoxia-inducible factor-1alpha axis.

PURPOSE: Despite recent progress, colon cancer is often resistant to combination chemotherapy, highlighting the need for development of novel therapeutic approaches. An attractive target is hypoxia-inducible factor-1alpha (HIF-1alpha), a key transcription factor with a pivotal role in tumor cell metabolism. One potential class of therapeutic agents targeting HIF-1alpha are mammalian target of rapamycin inhibitors such as rapamycin. A second class are topoisomerase I inhibitors, such as irinotecan, which are able to inhibit the accumulation of HIF-1alpha. We here investigated whether combination of rapamycin and irinotecan was active in human colon cancer models. EXPERIMENTAL DESIGN: Human metastatic tumors were xenografted in nude mice and treated with low doses of irinotecan alone, rapamycin alone, or combination of both drugs. The cellular effects of irinotecan and rapamycin were further characterized for HT-29 and HCT-116 colon cancer cells in vitro. RESULTS: In contrast to single-agent therapy, xenografted tumors treated with combination of irinotecan and rapamycin showed potent inhibition of the mammalian target of rapamycin/HIF-1alpha axis, which was accompanied by a dramatic reduction in tumor volume. In vitro experiments showed that exposure to low concentrations of the two drugs resulted in massive HT-29 cell death under hypoxic, but not normoxic, conditions, in full agreement with a cytotoxic effect mediated through HIF-1alpha rather than through induction of genotoxic lesions. HCT-116 cells were less sensitive to the combined treatment due to constitutive activation of phosphatidylinositol 3-kinase/Akt and Ras/mitogen-activated protein kinase pathways. CONCLUSION: These results identify HIF-1alpha as a promising target and provide a rationale for clinical trials of low-dose irinotecan and rapamycin combination toward metastatic colon cancer.

Impact of pemetrexed chemotherapy on the gut microbiota and intestinal inflammation of patient-lung-derived tumor xenograft (PDX) mouse models.

Chemotherapy remains the gold standard for advanced cancer. Pemetrexed, a chemotherapeutic agent used in non-small cell lung cancer, can induce significant side effects in patients. Although microbiota's role in the efficacy and/or toxicity of chemotherapy agents has been demonstrated, the impacts of pemetrexed on the gut microbiota and on gastrointestinal inflammation remain unknown. The objective of this study was to evaluate the impact of pemetrexed and the tumor graft on the gut microbiota composition in immunodeficient mice. The faecal microbiota composition was studied with metabarcoding before, 24-h and one week after treatment. The colon epithelial barrier integrity was evaluated by histological examination, intestinal permeability measurement, and selected cytokines quantification. The tumor graft induced some variations in the microbiota composition. Pemetrexed further increased the relative abundance of Enterobacteriaceae and 3 families from the Firmicutes phylum: Enterococcaceae, Lactobacillaceae and Streptococcaceae. Pemetrexed also significantly altered the epithelial barrier integrity, which was associated with early inflammation. This pilot study shows that the association of a lung tumor graft with pemetrexed causes an alteration in the microbiota composition. Such information increases our knowledge about the impact of chemotherapy on the microbiota, which could help to minimize side effects and improve therapeutic effectiveness in the future.

Synergistic Anti-Tumor Effect of mTOR Inhibitors with Irinotecan on Colon Cancer Cells.

Advanced colorectal cancer has a poor prognosis because of metastasis formation and resistance to combined therapies. Downstream of PI3K/Akt and Ras/MAPK pathways, the mTOR kinase plays a decisive role in treatment failure. We previously established that irinotecan has antiangiogenic properties and it is known that new mammalian target of rapamycin (mTOR) catalytic AZD inhibitors, unlike rapamycin, target both mTORC1 and mTORC2. Thus, we hypothesized that the complete inhibition of the PI3K/AKT/mTOR/HIF-1α axis with mTOR catalytic inhibitors and low doses of irinotecan may have antitumor effects. We showed that the AZD8055 and AZD2014 inhibitors were much more potent than rapamycin to reduce cell viability of four colon cell lines. On the other hand, whereas AZD2014 alone inhibits migration by 40%, the drug combination led to 70% inhibition. Similarly, neither irinotecan nor AZD2014 significantly reduced cell invasion, whereas a combination of the two inhibits invasion by 70%. In vivo, irinotecan and AZD2014 combination drastically reduced ectopic patient-derived colon tumor growth and this combination was more potent than Folfox or Folfiri. Finally, the combination totally inhibited liver and lung metastases developed from orthotopic implantation of SW480 cells. Thus, the use of mTOR catalytic inhibitors, in association with other chemotherapeutic agents like irinotecan at low doses, is potentially a hope for colon cancer treatment.