Progressive cellular response in the lamina propria of the colorectal adenoma-carcinoma sequence

Differential profile of protumor immunological factors between the tumor site and the tumor-free site - predictive potential of IL-8 and COX2 for colorectal cancer and metastasis

To study the role of host immune surveillance in the initiation and progression of colorectal cancer (CRC), a set of protumor immunological factors was determined by quantitative real-time PCR (q-PCR) between the primary tumor and the adjacent tumor-free site tissues in 63 patients with colorectal neoplasms. Results showed that expression levels of interleukin (IL)-1β, IL-6, IL-8, IL-17A, IL-23, and cyclooxygenase 2 (COX2) mRNAs, except transforming growth factor beta (TGFβ), in adenoma tissues were significantly higher than that in relative adjacent tissues. Difference of immunological factor levels between adenoma and adjacent tissues (Δ values) was in an order of ΔIL-8 > ΔIL-6 > ΔIL-17A > ΔIL-1β > ΔCOX2 > ΔIL-23; Analysis showed that the value of ΔCOX2 correlated to the grade of dysplastic degree in patients with adenoma. Notably, levels of all these immunological factors in CRC tissues were continuously increased, the order of values of Δ immunological factors was ΔIL-8 > ΔCOX2 > ΔIL-6 > ΔIL-1β > ΔIL-17A > ΔIL-23 > ΔTGFβ. Further analysis revealed that increased value of Δ IL-1β was associated with advanced TNM stage, a higher value of Δ COX2 tended to predicate a deeper degree of tumor invasion; and higher values of Δ IL-1β, IL-6 and COX2 closely correlated to lymph node metastasis in patients with CRC. In addition, the ratio of ΔIL-8/ΔTGFβ was most obvious changed factor and associated with node metastasis in patients with CRC. Therefore, we concluded that the difference of protumor immunological factor levels between the primary tumor site and tumor-free site along the adenoma-carcinoma sequence reflects the change of protumor/antitumor force balance, which is associated with CRC initiation and invasion.

Endothelial cells-directed angiogenesis in colorectal cancer: Interleukin as the mediator and pharmacological target

Enhanced angiogenesis is a cancer hallmark and critical for colorectal cancer (CRC) invasion and metastasis. Upon exposure to proangiogenic factors, therefore, targeting tumor-associated proangiogenic factors/receptors hold great promise as a therapeutic modality to treat CRC, particularly metastatic CRC. Accumulating evidence from numerous studies suggests that tumor endothelial cells (ECs) are not only the target of proangiogenic factors, but also function as the cellular source of proangiogenic factors. Studies showed that ECs can produce different proangiogenic factors to participate in the regulation of angiogenesis process, in which ECs-derived interleukins (ILs) show a potential stimulatory effect on angiogenesis via either an direct action on their receptors expressed on progenitor of ECs or an indirect way through enhanced production of other proangiogenic factors. Although a great deal of attention is given to the effects of tumor-derived and immune cell-derived ILs, few studies describe the potential effects of vascular ECs-derived ILs on the tumor angiogenesis process. This review provides an updated summary of available information on proangiogenic ILs, such as IL-1, IL-6, IL-8, IL-17, IL-22, IL-33, IL-34, and IL-37, released by microvascular ECs as potential drivers of the tumor angiogenesis process and discusses their potential as a novel candidate for antiangiogenic target for the treatment of CRC patients.

Cytokine-mediated crosstalk between cancer stem cells and their inflammatory niche from the colorectal precancerous adenoma stage to the cancerous stage: Mechanisms and clinical implications

The majority of colorectal cancers (CRCs) are thought to arise from precancerous adenomas. Upon exposure to diverse microenvironmental factors, precancerous stem cells (pCSCs) undergo complex genetic/molecular changes and gradually progress to form cancer stem cells (CSCs). Accumulative evidence suggests that the pCSC/CSC niche is an inflammatory dominated milieu that contains different cytokines that function as the key communicators between pCSCs/CSCs and their niche and have a decisive role in promoting CRC development, progression, and metastasis. In view of the importance and increasing data about cytokines in modulating pCSCs/CSC stemness properties and their significance in CRC, this review summarizes current new insights of cytokines, such as interleukin (IL)-4, IL-6, IL-8, IL-17A, IL-22, IL-23, IL-33 and interferon (IFN)-γ, involving in the modulation of pCSC/CSC properties and features in precancerous and cancerous lesions and discusses the possible mechanisms of adenoma progression to CRCs and their therapeutic potential.

The Expression Pattern of Bcl-2 and Bax in the Tumor and Stromal Cells in Colorectal Carcinoma

Background and objectives: The epithelial and stromal tissues both play a role in the progression of colorectal cancer (CRC). The aim of this study was to assess the expression of anti-apoptotic Bcl-2 and pro-apoptotic Bax in the epithelium as well as the lamina propria of normal colonic controls, low-grade tumor samples and high-grade tumor samples. Materials and Methods: A total of 60 samples consisting of both normal colonic and carcinoma samples was collected from the Department of Pathology, Cytology and Forensic Medicine, University Hospital Center, Split from January 2020 to December 2021. The expression of Bcl-2 and Bax markers was semi-quantitatively and quantitatively evaluated by recording immunofluorescence stain intensity and by counting stained cells in the lamina propria and epithelium. Analysis of positive cells was performed using the Mann-Whitney test. Results: In all samples, Bcl-2 was significantly more expressed in the lamina propria when compared with the epithelium. Bax was significantly more expressed in the epithelium of normal and low-grade cancer samples when compared with their respective laminae propriae. The percentage of Bcl-2-positive cells in lamina propria is about two times lower in high-grade CRC and about three times lower in low-grade CRC in comparison with healthy controls. Contrary to this, the percentage of Bax-positive cells was greater in the epithelium of low-grade CRC in comparison with healthy control and high-grade CRC. Conclusions: Our study provides a new insight into Bcl-2 and Bax expression pattern in CRC. Evaluation of Bcl-2 expression in the lamina propria and Bax expression in the epithelium could provide important information for colorectal cancer prognosis as well as potential treatment strategies.

The Adaptive Immune Landscape of the Colorectal Adenoma-Carcinoma Sequence

BACKGROUND

The tumor immune microenvironment exerts a pivotal influence in tumor initiation and progression. The aim of this study was to analyze the immune context of sporadic and familial adenomatous polyposis (FAP) lesions along the colorectal adenoma-carcinoma sequence (ACS).

METHODS

We analyzed immune cell counts (CD3+, CD4+, CD8+, Foxp3+, and CD57+), tumor mutation burden (TMB), MHC-I expression and PD-L1 expression of 59 FAP and 74 sporadic colorectal lesions, encompassing adenomas with low-grade dysplasia (LGD) (30 FAP; 30 sporadic), adenomas with high-grade dysplasia (22 FAP; 30 sporadic), and invasive adenocarcinomas (7 FAP; 14 sporadic).

RESULTS

The sporadic colorectal ACS was characterized by (1) a stepwise decrease in immune cell counts, (2) an increase in TMB and MHC-I expression, and (3) a lower PD-L1 expression. In FAP lesions, we observed the same patterns, except for an increase in TMB along the ACS. FAP LGD lesions harbored lower Foxp3+ T cell counts than sporadic LGD lesions. A decrease in PD-L1 expression occurred earlier in FAP lesions compared to sporadic ones.

CONCLUSIONS

The colorectal ACS is characterized by a progressive loss of adaptive immune infiltrate and by the establishment of a progressively immune cold microenvironment. These changes do not appear to be related with the loss of immunogenicity of tumor cells, or to the onset of an immunosuppressive tumor microenvironment.

The inflammatory microenvironment in screen-detected premaligant adenomatous polyps: early results from the integrated technologies for improved polyp surveillance (INCISE) project

INTRODUCTION

Around 40% of patients who attend colonoscopy following a positive stool screening test have adenomatous polyps. Identifying which patients have a higher propensity for malignant transformation is currently poorly understood. The aim of the present study was to assess whether the type and intensity of inflammatory infiltrate differ between screen-detected adenomas with high-grade dysplasia (HGD) and low-grade dysplasia (LGD).

METHODS

A representative sample of 207 polyps from 134 individuals were included from a database of all patients with adenomas detected through the first round of the Scottish Bowel Screening Programme in NHS Greater Glasgow and Clyde (April 2009-April 2011). Inflammatory cell phenotype infiltrate was assessed by immunohistochemistry for CD3+, CD8+, CD45+ and CD68+ in a semi-quantitative manner at 20× resolution. Immune-cell infiltrate was graded as absent, weak, moderate or strong. Patient and polyp characteristics and inflammatory infiltrate were then compared between HGD and LGD polyps.

RESULTS

CD3+ infiltrate was significantly higher in HGD polyps compared to LGD polyps (74 vs. 69%; P < 0.05). CD8+ infiltrate was significantly higher in HGD polyps compared to LGD polyps (36 vs. 13%; P < 0.001) whereas CD45+ infiltrate was not significantly different (69 vs. 64%; P = 0.401). There was no significant difference in CD68+ infiltrate (P = 0.540) or total inflammatory cell infiltrate (calculated from CD3+ and CD68+) (P = 0.226).

CONCLUSIONS

This study reports an increase in CD3+ and CD8+ infiltrate in HGD colonic adenomas when compared to LGD adenomas. It may therefore have a use in the prognostic stratification and treatment of dysplastic polyps.

Dynamic stromal cellular reaction throughout human colorectal adenoma-carcinoma sequence: A role of TH17/IL-17A

BACKGROUND

Accumulating data suggest that the tumour stroma rapidly undergoes dynamic mechanical and cellular changes by which creates a supportive milieu to promote disease progression and metastasis. Cytokines are reported to play a key role in the modulation of tumour stromal response.

METHODS

The activation of TH17/interleukin (IL)-17A network in association with tumour stromal proliferative and cellular response in samples from 50 patients with colorectal adenoma, 45 with colorectal cancer (CRCs) were elucidated with quantitative real-time PCR (q-PCR), immunohistochemistry and double immunofluorescence.

RESULTS

q-PCR results showed that retinoic acid-receptor-related orphan receptor-C, a critical transcriptional factor for TH17 cell differentiation, was significantly increased at the adenoma stage and slightly decreased at the CRC stage, but was still higher than that at normal controls. The level of TH17 signature cytokine IL-17A was shown in an increasing gradient throughout the adenoma-carcinoma sequence. Immunohistochemistry revealed an activated proliferative rate evaluated by Ki67 and population expansion of myofibroblasts in the adenoma/CRC stroma. Notably, densities of IL-17A-expressing cells were associated with populations of Ki67-positive cells and myofibroblasts in the adenoma/CRC stroma. Finally, CD146-positive stromal cells are an important participator for stroma remodelling, double immunofluorescence image demonstrated that IL-17 receptor C, one of the key elements for IL-17 receptor complex, was highly expressed in CD146-positive adenoma/CRC stromal cells.

CONCLUSIONS

An activated TH17/IL-17A network in the tumour microenvironment is significantly associated with dynamic stromal cellular response throughout the adenoma-carcinoma sequence, which might provide a supportive environment for the initiation and progression of CRC.

ST2 and regulatory T cells in the colorectal adenoma/carcinoma microenvironment: implications for diseases progression and prognosis

ST2 (also known as IL1RL1) is the critical functional receptor for interleukin (IL)-33 in stimulating regulatory T cell (Treg) expansion and function in physiological and pathological conditions. We examined the correlation between ST2 cell expression and FoxP3 positive Tregs in both colorectal adenoma and cancer (CRC) microenvironment by real-time PCR, immunohistochemistry (IHC) and double immunofluorescences. The clinicopathological and prognostic significance of cellular ST2-positive cells and FoxP3-positive Tregs in patients with adenoma and CRC were evaluated. Real-time PCR results revealed increased expression levels of ST2 and FoxP3 mRNAs in both adenoma and CRC tissues as compared with control tissues. IHC analysis confirmed increased densities of ST2-positive cells in both the adenoma/CRC epithelium and stroma, which show a close positive linear association with the densities of FoxP3-positive Tregs in respective compartments. Pathological feature analysis showed that densities of ST2-positive cells in the tumor stroma were notably associated with degree of dysplastic grading in patients with adenoma, and disease stages and lymph node metastasis in patients with CRC. Kaplan-Meier survival curves suggested that CRC patients with high densities of ST2-positive cells in the stroma tend to have a shorter overall survival. We therefore concluded that increased densities of ST2-postive cells relate to Treg accumulation within the adenoma/CRC microenvironment, suggesting the IL-33/ST2 pathway as a potential contributor for immunosuppressive milieu formation that impact disease stage and prognosis in patients with CRC.

TH9, TH17, and TH22 Cell Subsets and Their Main Cytokine Products in the Pathogenesis of Colorectal Cancer

In recent years, several newly identified T helper (T_H) cell subsets, such as T_H9, T_H17, and T_H22 cells, and their respective cytokine products, IL-9, IL-17, and IL-22, have been reported to play critical roles in the development of chronic inflammation in the colorectum. Since chronic inflammation is a potent driving force for the development of human colorectal cancer (CRC), the contributions of T_H9/IL-9, T_H17/IL-17, and T_H22/IL-22 in the pathogenesis of CRC have recently become an increasingly popular area of scientific investigation. Extensive laboratory and clinical evidence suggests a positive relationship between these new T_H subsets and the growth and formation of CRC, whereas, administration of IL-9, IL-17, and IL-22 signaling inhibitors can significantly alter the formation of colorectal chronic inflammation or CRC lesions in animal models, suggesting that blocking these cytokine signals might represent promising immunotherapeutic strategies. This review summarizes recent findings and currently available data for understanding the vital role and therapeutic significance of T_H9/IL-9, T_H17/IL-17, and T_H22/IL-22 in the development of colorectal tumorigenesis.

The Heterocellular Emergence of Colorectal Cancer

Tissues contain multiple different cell types and can be considered to be heterocellular systems. Signaling between different cells allows tissues to achieve phenotypes that no cell type can achieve in isolation. Such emergent tissue-level phenotypes can be said to 'supervene upon' heterocellular signaling. It is proposed here that cancer is also an emergent phenotype that supervenes upon heterocellular signaling. Using colorectal cancer (CRC) as an example, I review how heterotypic cells differentially communicate to support emergent malignancy. Studying tumors as integrated heterocellular systems - rather than as solitary expansions of mutated cells - may reveal novel ways to treat cancer.

Temporal and spatial changes of cells positive for stem-like markers in different compartments and stages of human colorectal adenoma-carcinoma sequence

Considerable evidence supports the idea that stem-like cells may play an essential role during the development of colorectal cancer (CRC). To accomplish this aim, we use immunohistochemistry (IHC) and double IHC with different potential stem-like markers, anti-musashi (Msi), anti-CD133, anti- LGR5 and anti-ALDH1 to examine the presentation of stem-like cells in different compartments including adenoma/CRC epithelium, transitional crypts and tumor stroma in colorectal adenoma and CRC. The results showed that cells positive for stem-like markers were remarkably increased in number and frequently observed in the adenoma/CRC epithelium, transitional crypts and tumor stroma. Notably, the population of cells positive for stem-liker markers was expanded from the base to the middle part of the transitional crypt in both adenoma and CRC tissues, reflecting that stem-like cells are likely involved in the process of colorectal tumorigenesis. Counting results showed that the grading scores of cells positive for LGR5 and ALDH1 in the adenoma/CRC epithelium were significantly increased relative with the control epithelium, and associated with the degree of dysplasia in the adenoma and node involvement in the CRC (all P < 0.05). In addition, the density of cells positive for stem-like markers in the adenomatous/cancerous stroma was also increased and paralleled an increase in the density of proliferative stromal cells labeled by PCNA, which were primarily identified as vimentin positive fibroblasts. Our results have revealed a changed temporal and spatial presentation of stem-like markers in different stages of human colorectal adenoma-carcinoma sequence, which might be a hallmark of the adenoma-carcinoma transition.

Paracrine cyclooxygenase-2 activity by macrophages drives colorectal adenoma progression in the Apc Min/+ mouse model of intestinal tumorigenesis

Genetic deletion or pharmacological inhibition of cyclooxygenase (COX)-2 abrogates intestinal adenoma development at early stages of colorectal carcinogenesis. COX-2 is localised to stromal cells (predominantly macrophages) in human and mouse intestinal adenomas. Therefore, we tested the hypothesis that paracrine Cox-2-mediated signalling from macrophages drives adenoma growth and progression in vivo in the Apc^Min/+ mouse model of intestinal tumorigenesis. Using a transgenic C57Bl/6 mouse model of Cox-2 over-expression driven by the chicken lysozyme locus (cLys-Cox-2), which directs integration site-independent, copy number-dependent transgene expression restricted to macrophages, we demonstrated that stromal macrophage Cox-2 in colorectal (but not small intestinal) adenomas from cLys-Cox-2 x Apc^Min/+ mice was associated with significantly increased tumour size (P = 0.025) and multiplicity (P = 0.025), compared with control Apc^Min/+ mice. Transgenic macrophage Cox-2 expression was associated with increased dysplasia, epithelial cell Cox-2 expression and submucosal tumour invasion, as well as increased nuclear β-catenin translocation in dysplastic epithelial cells. In vitro studies confirmed that paracrine macrophage Cox-2 signalling drives catenin-related transcription in intestinal epithelial cells. Paracrine macrophage Cox-2 activity drives growth and progression of Apc^Min/+ mouse colonic adenomas, linked to increased epithelial cell β-catenin dysregulation. Stromal cell (macrophage) gene regulation and signalling represent valid targets for chemoprevention of colorectal cancer.

Tumor-Associated Fibroblasts and Microvessels Contribute to the Expression of Immunosuppressive Factor Indoleamine 2, 3-Dioxygenase in Human Esophageal Cancers

Recent studies have provided considerable evidence to support the hypothesis that tumor stroma plays a crucial role in the induction of immune tolerance to human cancers. Here, we investigated the contribution of reactive stromal tumor-associated fibroblasts (TAFs) and microvessels to the immunosuppressive factor indoleamine 2,3-dioxygenase (IDO) expression in the ESCC microenvironment. The immunohistochemical (IHC) analyses demonstrated a significant increased densities of TAFs and microvessels in the ESCC stroma, double IHCs showed that these increased TAFs and microvessels were with a high proliferation activity. Further IHC examinations revealed that increased expression of IDO were frequently observed in the stromal cells with TAF morphology and microvessels. Double immunofluorescence examinations confirmed the colocalization of IDO positive cells with SMA-alpha positive TAFs and CD34 positive endothelial cells in the ESCC stroma. Our current findings strongly suggest that the activated stromal TAFs and endothelial cells of microvessels contribute to the expression of IDO and then the orchestration of immunosuppressive microenvironment.

The Immune Landscapes of Polypoid and Nonpolypoid Precancerous Colorectal Lesions

Little is known about the immunoediting process in precancerous lesions. We explored this aspect of benign colorectal adenomas with a descriptive analysis of the immune pathways and immune cells whose regulation is linked to the morphology and size of these lesions. Two series of polypoid and nonpolypoid colorectal adenomas were used in this study: 1) 84 samples (42 lesions, each with matched samples of normal mucosa) whose gene expression data were used to quantify the tumor morphology- and size-related dysregulation of immune pathways collected in the Molecular Signature Database, using Gene Set Enrichment Analysis; 2) 40 other lesions examined with immunohistochemistry to quantify the presence of immune cells in the stromal compartment. In the analysis of transcriptomic data, 429 immune pathways displayed significant differential regulation in neoplasms of different morphology and size. Most pathways were significantly upregulated or downregulated in polypoid lesions versus nonpolypoid lesions (regardless of size). Differential pathway regulation associated with lesion size was observed only in polypoid neoplasms. These findings were mirrored by tissue immunostaining with CD4, CD8, FOXP3, MHC-I, CD68, and CD163 antibodies: stromal immune cell counts (mainly T lymphocytes and macrophages) were significantly higher in polypoid lesions. Certain markers displayed significant size-related differences regardless of lesion morphology. Multivariate analysis of variance showed that the marker panel clearly discriminated between precancerous lesions of different morphologies and sizes. Statistical analysis of immunostained cell counts fully support the results of the transcriptomic data analysis: the density of infiltration of most immune cells in the stroma of polypoid precancerous lesions was significantly higher than that observed in nonpolypoid lesions. Large neoplasms also have more immune cells in their stroma than small lesions. Immunoediting in precancerous colorectal tumors may vary with lesion morphology and stage of development, and this variability could influence a given lesion's trajectory to cancer.

Changes of immunocytic phenotypes and functions from human colorectal adenomatous stage to cancerous stage: Update

It is believed that chronic inflammation as seen in patients with ulcerative colitis significantly increases the colorectal cancer (CRC) risk and functions as the main driving force for the development of colitis associated CRC. Recently, increasing evidences suggest that inflammation is also involved in the processing of sporadic CRCs that mostly develop from the preformed adenomas through a long-term progression. Within the adenoma/CRC tumor microenvironment, high dense immunocytes with significant phenotypic and functional changes have been observed. These cells might produce high level of inflammatory mediators and then affect the adenoma-cancer transition. In this review, we summarize the update on altered phenotypes and inflammatory mediators within the tumor microenvironment from the adenomatous stage to the cancerous stage, and discuss the significance of inflammatory mediators as biomarkers in predicating the progression from the premalignant adenoma lesion to the sporadic CRC lesion and the potential as therapeutic targets.

Therapeutic efficacy of IL-17A antibody injection in preventing the development of colitis associated carcinogenesis in mice

Chronic inflammation increases colorectal cancer (CRC) risk as seen in ulcerative colitis (UC). Proinflammatory cytokines play a critical role in mediating the development of colitis associated cancer (CAC). In this study, the therapeutic efficacy of anti-interleukin (IL)-17A by anti-IL-17A antibody injection on the development of CAC was assessed in 1,2-dimethylhydrazine (DMH) plus dextran sulfate sodium (DSS) induced CAC mouse model. The results showed that mice dosed with DMH plus DSS for 10 weeks evoked high degree dysplastic lesion in the large bowel that accompanied with significant increased IL-17A expression, proliferation index and inflammation degree in mice. After anti-IL-17A antibody injection for 2 weeks, the number of tumors, proliferation index and the expression level of IL-17A protein in the large bowel tissues were significantly decreased. Therefore, we concluded that the anti-IL-17A blockade can suppress the development of CAC and is a potential therapeutic agent for the prevention of CAC in colitis mice.

Involvement of NF-κB/IL-6 Pathway in the Processing of Colorectal Carcinogenesis in Colitis Mice

Nuclear factor-kappaB (NF-κB)/interleukin (IL-6) pathway links chronic inflammation to colitis associated cancer (CAC). In this study, we examined the dynamic temporal changes of the NF-κB/IL-6 pathway during the procession of experimental CAC mouse model. Mice were sacrificed after induction for 14, 16, 18, and 22 weeks for the examination of tumor burden, inflammation degree, and protein level of NF-κB and IL-6 in bowel tissues. The results showed that tumor burden and inflammation severity in the bowels were gradually increased over the observed time-points. The expressions of IL-6 and NF-κB proteins were gradually increased after induction of dysplastic lesions over times. These data provide new information on the dynamic temporal changes of NF-κB/IL-6 pathway in relation to CAC development that may be relevant in the design of future investigations of therapeutic interventions to effectively target CAC processes.

Elevated proinflammatory cytokine IL-17A in the adjacent tissues along the adenoma-carcinoma sequence

Considerable evidence has suggested that chronic inflammation is a causative factor in the development of human colorectal cancer (CRC). Interleukin (IL)-17A produced mainly by Th17 cells is a novel proinflammatory cytokine and increased IL-17A is associated with colorectal neoplastic transformation. In this study, we have evaluated the expression of IL-17A in the adjacent tissues along the colorectal adenoma-carcinoma sequence. The expression of IL-17A in the adjacent tissues of colorectal adenoma (adenoma-adjacent, n = 32) and sporadic CRC (CRC-adjacent, n = 45) was examined. In addition, the expression pattern of Th17 cell differentiation stimulators (IL-1β, IL-6 and IL-23A) in the adjacent tissues were also examined. The results showed that the expression level of IL-17A mRNA was non-statistically increased (4-fold higher) in the adenoma-adjacent tissues and it became significantly increased (9-fold higher) in the CRC-adjacent tissues as compared with the control. The expression level of IL-17A in the CRC-adjacent tissues was not associated with CRC clinicopathological parameters and overall survival. Immunohistochemistry confirmed an increased density of intraepithelial IL-17A expressing cells in the CRC-adjacent tissues. The Th17 cell differentiation simulators IL-1β and IL-6 were also shown in an increase trend from the adenoma-adjacent to CRC-adjacent tissues. These results provide evidence that IL-17A/Th17 response is enhanced in the adjacent tissues during the colorectal neoplastic transformation.

Bone marrow-derived myofibroblasts promote colon tumorigenesis through the IL-6/JAK2/STAT3 pathway

Bone marrow-derived myofibroblasts (BMFs) have been shown to promote tumor growth. Here, we found that BMFs or BMF conditioned medium (BMF-CM) induced cancer stem cell-like sphere formation of colon cancer cells. The co-cultured BMFs, but not co-cultured cancer cells, expressed higher levels of IL-6 than BMFs or cancer cells cultured alone. Anti-mouse IL-6 neutralizing antibody, JAK2 inhibitors and STAT3 knockdown in mouse cancer cells reduced BMF- and BMF-CM-induced sphere formation of colon cancer cells. When co-injected, BMFs significantly enhanced tumorigenesis of colon cancer cells in mice. Our results demonstrate that BMFs promote tumorigenesis via the activation of the IL-6/JAK2/STAT3 pathway.

IL-17A in the tumor microenvironment of the human colorectal adenoma-carcinoma sequence

OBJECTIVES

Interleukin (IL)-17A is an important pro-inflammatory cytokine and involved in the colorectal carcinogenesis. In this study, the authors evaluated the dynamic change of IL-17A expression in the tumor microenvironment throughout the colorectal adenoma-carcinoma sequence.

MATERIALS & METHODS

Using quantitative real-time PCR (polymerase chain reaction) and semi-quantitative immunohistochemistry, the authors examined the expression level of IL-17A in 50 of human colorectal adenoma tissues, 50 of colorectal cancer (CRC) tissues and 15 controls. The relationship between IL-17A expression and clinicopathological parameters throughout the sequence was also evaluated.

RESULTS

The results revealed a step-up increased IL-17A mRNA level throughout the colorectal adenoma-carcinoma sequence, which began to increase in the adenomas and became even higher in the CRCs; notably, the increase of IL-17A mRNA level in the adenomatous tissues was associated with the severity of dysplasia. Immunohistochemical analysis confirmed the real-time PCR results and revealed gradually increasing IL-17A cells in both the stroma and adenomatous/cancerous epithelium. In addition, the quantitative real-time PCR result has also revealed an increased expression of TH17-stimulating factors throughout the sequence.

CONCLUSIONS

IL-17A and TH17 are highly activated throughout the colorectal adenoma-carcinoma sequence.

Immune microenvironmental shift along human colorectal adenoma-carcinoma sequence: is it relevant to tumor development, biomarkers and biotherapeutic targets?

Human colorectal carcinoma (CRC) is one of the leading cancers. Every year, the WHO estimates a total of 945,000 new CRC cases, with 492,000 deaths worldwide. Most CRCs arise from the main premalignant lesion, colorectal adenomas, and the progression of colorectal adenoma to CRCs may take a long-term time course. The development of human CRCs is not only determined by the adenomatous cells, but also by the interaction between adenomatous cells and host immune environment. In response to tumor initiation or invasion, many inflammatory cells and components will be inevitably activated and form an inflammatory microenvironment surrounding the CRC tumors. Accumulative evidence has revealed that inflammatory response plays a key role in the development of human CRCs by implicating in many aspects including in determining the microenvironmental immune function shift from immunosurveillance to immunosuppression and significantly influences the progression of precancerous lesions to cancers. In this review, the functional changes of immune microenvironment from precancerous stage (adenoma) to cancer stage are summarized, and their potential as predictive biomarkers and biotherapeutic significance in preventing the development of CRCs are discussed.

Clinicopathological significance of indoleamine 2,3-dioxygenase 1 expression in colorectal cancer

BACKGROUND

Indoleamine 2,3-dioxygenase 1 (IDO1) is a tryptophan-catabolising enzyme that induces immune tolerance by modulating T-cell responses. Carcinomas may create an immunosuppressive state via IDO1 expression. Here we examined a possible contribution of IDO1 on this phenomenon and investigated whether IDO1 has prognostic value in colorectal cancer (CRC).

METHODS

IDO1 expression was investigated by quantitative PCR and western blotting in three colon cancer cell lines, in basal state and after interferon (IFN)-γ stimulation. Semi-quantitative immunohistochemistry was used to evaluate IDO1 expression in 265 pT1-4N0-2Mx-staged CRCs. Results were related to clinical variables and correlated with amounts of CD3(+) and CD8(+) T lymphocytes, which were quantitatively evaluated using image analysis.

RESULTS

In vitro expression of IDO1 depended on IFN-γ stimulation. Higher IDO1 expression at the tumour invasion front was an independent adverse prognostic factor in pT1-4N1Mx-staged CRC. It was associated with overall survival (P=0.001) and with metachronous metastases (P=0.018). IDO1 expression was not associated with the presence of CD3(+) or CD8(+) T lymphocytes.

CONCLUSION

Higher IDO1 expression at the tumour invasion front is involved in CRC progression and correlates with impaired clinical outcome, suggesting that IDO1 is an independent prognostic indicator for CRC.

The role of tumour stroma in colorectal cancer invasion and metastasis

Colorectal cancer (CRC) is a major cause of mortality in western society with a 5-year survival of approximately 50%. Metastasis to the liver and lungs is the principal cause of death and occurs in up to 25% of patients at presentation. Despite advances in available techniques for treating metastases, the majority of patients remain incurable and existing adjuvant therapies such as chemotherapy are only of limited effectiveness. Understanding the molecular mechanisms underlying the metastatic process may allow us to identify those at greatest risk of recurrence and discover new tumour targets to prevent disease progression. It is now apparent that tumour stroma plays an important role in promoting tumour progression. A pronounced desmoplastic reaction was associated with a reduced immune response and has been shown to be an independent poor prognostic indicator in CRC and cancer recurrence. Determining the cause(s) and effect(s) of this stromal response will further our understanding of tumour cell/stromal interactions, and will help us identify prognostic indicators for patients with CRC. This will not only allow us to target our existing treatments more effectively, we also aim to identify novel and more specific therapeutic targets for the treatment of CRC which will add to our current therapeutic options.

New specific molecular targets for radio-chemotherapy of rectal cancer

Patients with locally advanced rectal cancer often receive preoperative radio-chemotherapy (RCT). The mechanisms of tumour response to radiotherapy are not understood. The aim of this study was to identify the effects of RCT on gene expression in rectal tumour and normal rectal tissue. For that purpose tissue samples from 21 patients with resectable adenocarcinomas were collected for use in whole genome-microarray based gene expression analysis. A factorial experimental design allowed us to determine the effect of RCT on tumour tissue alone by removing the effect of radiation on normal tissue. This resulted in 1327 differentially expressed genes in tumour tissue with p<0.05. In addition to known markers for radio-chemotherapy, a Gene Set Enrichment Analysis (GSEA) showed a significant enrichment in gene sets associated with cell adhesion and leukocyte transendothelial migration. The profound change of cell adhesion molecule expression in rectal tumour tissue could either increase the risk of metastasis, or decrease the tumour's invasive potential.

Dynamic changes of interleukin-8 network along the colorectal adenoma-carcinoma sequence

The interleukin-8 (IL-8) network is involved in the colorectal cancer (CRC) progression. However, its role during the adenoma-carcinoma transition to date has not been fully investigated. To evaluate the dynamic changes of IL-8 network along the colorectal adenoma-carcinoma sequence, we examined the tissue IL-8 mRNA level in colorectal biopsies from 53 colorectal adenomas, 44 CRCs and 18 controls by quantitative real-time PCR (Q-PCR), and the expressions of IL-8 and its receptors (IL-8RA and IL-8RB) in the tumor microenvironment by immunohistochemistry (IHC) and double IHCs. The results showed that the tissue IL-8 mRNA level began to increase in the precancerous lesions (adenomas) as compared with the controls and became even higher in the CRCs. Significantly, the increase of IL-8 mRNA levels was associated with the increase of dysplastic grades in the adenomas, and also paralleled to the increase of Duke's stages in the CRCs. IHC results revealed that IL-8 and its receptors, IL-8RA and IL-8RB, were observed both in the stroma and in the adenomatous/cancerous cells. By double IHCs, the IL-8 expression was characterized in macrophages, lymphocytes and myofibroblasts in the tumor stroma. Further double IHC identified the co-expression of IL-8 receptors (IL-8RA and IL-8RB) with CD34 positive tumor-associated microvessels in both the adenomas and CRCs. We, therefore, conclude that activated IL-8 network in the tumor microenvironment may function as a significant regulatory factor for the adenoma progression and the adenoma-carcinoma transition.