The prognostic value of cancer stem-like cell markers SOX2 and CD133 in stage III colon cancer is modified by expression of the immune-related markers FoxP3, PD-L1 and CD3

Challenges and opportunities for cancer stem cell-targeted immunotherapies include immune checkpoint inhibitor, cancer stem cell-dendritic cell vaccine, chimeric antigen receptor immune cells, and modified exosomes

Cancer stem cells (CSCs) are associated with the tumor microenvironment (TME). CSCs induce tumorigenesis, tumor recurrence and progression, and resistance to standard therapies. Indeed, CSCs pose an increasing challenge to current cancer therapy due to their stemness or self-renewal properties. The molecular and cellular interactions between heterogeneous CSCs and surrounding TME components and tumor-supporting immune cells show synergistic effects toward treatment failure. In the immunosuppressive TME, CSCs express various immunoregulatory proteins, growth factors, metabolites and cytokines, and also produce exosomes, a type of extracellular vesicles, to protect themselves from host immune surveillance. Among these, the identification and application of CSC-derived exosomes could be considered for the development of therapeutic approaches to eliminate CSCs or cancer, in addition to targeting the modulators that remodel the composition of the TME, as reviewed in this study. Here, we introduce the role of CSCs and how their interaction with TME complicates immunotherapies, and then present the CSC-based immunotherapy and the limitation of these therapies. We describe the biology and role of tumor/CSC-derived exosomes that induce immune suppression in the TME, and finally, introduce their potentials for the development of CSC-based targeted immunotherapy in the future.

Crosstalk between colorectal CSCs and immune cells in tumorigenesis, and strategies for targeting colorectal CSCs

Cancer immunotherapy has emerged as a promising strategy in the treatment of colorectal cancer, and relapse after tumor immunotherapy has attracted increasing attention. Cancer stem cells (CSCs), a small subset of tumor cells with self-renewal and differentiation capacities, are resistant to traditional therapies such as radiotherapy and chemotherapy. Recently, CSCs have been proven to be the cells driving tumor relapse after immunotherapy. However, the mutual interactions between CSCs and cancer niche immune cells are largely uncharacterized. In this review, we focus on colorectal CSCs, CSC-immune cell interactions and CSC-based immunotherapy. Colorectal CSCs are characterized by robust expression of surface markers such as CD44, CD133 and Lgr5; hyperactivation of stemness-related signaling pathways, such as the Wnt/β-catenin, Hippo/Yap1, Jak/Stat and Notch pathways; and disordered epigenetic modifications, including DNA methylation, histone modification, chromatin remodeling, and noncoding RNA action. Moreover, colorectal CSCs express abnormal levels of immune-related genes such as MHC and immune checkpoint molecules and mutually interact with cancer niche cells in multiple tumorigenesis-related processes, including tumor initiation, maintenance, metastasis and drug resistance. To date, many therapies targeting CSCs have been evaluated, including monoclonal antibodies, antibody‒drug conjugates, bispecific antibodies, tumor vaccines adoptive cell therapy, and small molecule inhibitors. With the development of CSC-/niche-targeting technology, as well as the integration of multidisciplinary studies, novel therapies that eliminate CSCs and reverse their immunosuppressive microenvironment are expected to be developed for the treatment of solid tumors, including colorectal cancer.

Clinicopathological and prognostic significance of PD-L1 expression in colon adenocarcinoma tumor budding

OBJECTIVE

In this study, we investigated the relationship between programmed cell death ligand 1 (PD-L1) and programmed cell death protein 1 (PD-1) expression in colon adenocarcinoma tumor budding.

METHODS

This study included 122 patients with colon adenocarcinomas. The largest sample of formaldehyde-fixed paraffin-embedded tumor tissues was selected for analysis. Expression of membranous PD-L1 (clone 22C3) and the Combined Positive Score (CPS) in tumor tissues was calculated and graded according to the percentages of peritumoral and intratumoral tumor cells (0 %, 1 %, 1-5 %, >5 %). The effects of these factors on the prognosis were analyzed.

RESULTS

Tumor budding was associated with adverse clinicopathological features and poor overall survival. PD-L1 (CPS%) peritumoral tumor budding (1 %/<1 %) was statistically significant in the univariate model (p = 0.004). Age, organ metastases (liver, lung, liver, lung, and peritoneum), and metastases were statistically significant in the multivariate model (p = 0.001, p = 0.004, p = 0.001, p = 0.002, p = 0.004, and p = 0.032, respectively). PD-L1 positive staining was mostly observed around the tumor and during tumor budding. PD-L1 peritumoral tumor budding rates and patients' survival rates differed significantly (log-rank = 12.07, p = 0.007).

CONCLUSION

We found that patients with PD-L1 (CPS%) > 1 % in tumor budding had a shortened life expectancy and demonstrated the importance of including tumor budding areas in the samples used for biomarker evaluation. We previously reported that PD-L1 expression in tumor budding is associated with more aggressive cancer biology and poor survival, although overall survival is of limited statistical significance.

Cross-talk between cancer stem cells and immune cells: potential therapeutic targets in the tumor immune microenvironment

Ongoing research has revealed that the existence of cancer stem cells (CSCs) is one of the biggest obstacles in the current cancer therapy. CSCs make an influential function in tumor progression, recurrence and chemoresistance due to their typical stemness characteristics. CSCs are preferentially distributed in niches, and those niche sites exhibit characteristics typical of the tumor microenvironment (TME). The complex interactions between CSCs and TME illustrate these synergistic effects. The phenotypic heterogeneity within CSCs and the spatial interactions with the surrounding tumor microenvironment led to increased therapeutic challenges. CSCs interact with immune cells to protect themselves against immune clearance by exploiting the immunosuppressive function of multiple immune checkpoint molecules. CSCs also can protect themselves against immune surveillance by excreting extracellular vesicles (EVs), growth factors, metabolites and cytokines into the TME, thereby modulating the composition of the TME. Therefore, these interactions are also being considered for the therapeutic development of anti-tumor agents. We discuss here the immune molecular mechanisms of CSCs and comprehensively review the interplay between CSCs and the immune system. Thus, studies on this topic seem to provide novel ideas for reinvigorating therapeutic approaches to cancer.

Cancer stem cell marker expression and methylation status in patients with colorectal cancer

The number of individuals diagnosed with colorectal cancer (CRC) has been on an alarming upward trajectory over the past decade. In some countries, this cancer represents one of the most frequently diagnosed types of neoplasia. Therefore, it is an important demand to study the pathology underlying this disease to gain insights into the mechanism of resistance to treatment. Resistance of tumors to chemotherapy and tumor aggressiveness have been associated with a minor population of neoplastic cells, which are considered to be responsible for tumor recurrence. These types of neoplastic cells are known as cancer stem cells, which have been previously reported to serve an important role in pathogenesis of this malignant disease. Slovakia has one of the highest incidence rates of CRC worldwide. In the present study, the aim was to classify the abundance of selected stem cell markers (CD133, CD166 and Lgr5) in CRC tumors using flow cytometry. In addition, the methylation status of selected genomic regions of CRC biomarkers (ADAMTS16, MGMT, PROM1 (CD133), LGR5 and ALCAM) was investigated by pyrosequencing in a cohort of patients from Martin University Hospital, Martin, Slovakia. Samples from both primary tumors and metastatic tumors were tested. Analysis of DNA methylation in the genomic regions of indicated five CRC biomarkers was also performed, which revealed the highest levels of methylation in the A disintegrin and metalloproteinase with thrombospondin motifs 16 and O6-methyguanine-DNA methyl transferase genes, whereas the lowest levels of methylation were found in genes expressing prominin-1, leucine-rich repeat-containing G-protein-coupled receptor 5 and activated leukocyte cell adhesion molecule. Furthermore, tumor tissues from metastases showed significantly higher levels of CD133⁺ cells compared with that in primary tumors. Higher levels of CD133⁺ cells correlated with TNM stage and the invasiveness of CRC into the lymphatic system. Although relatively small number of samples was processed, CD133 marker was consider to be important marker in pathology of CRC.

An exploration of immunohistochemistry-based prognostic markers in patients undergoing curative resections for colon cancer

Background

The immune system recognizes and destroys cancer cells. However, cancer cells develop mechanisms to avoid detection by expressing cell surface proteins. Specific tumour cell surface proteins (e.g. HLA-G, PD-L1, CDX2) either alone or in combination with the relative presence of immune cells (CD3 and CD8 positive T-cells) in the tumour tissue may describe the cancer cells’ ability to escape eradication by the immune system. The aim was to investigate the prognostic value of immunohistochemical markers in patients with colon cancer.

Methods

We conducted a retrospective study including patients diagnosed with pT3 and pT4 colon cancers. Immunohistochemical staining with HLA-G, PD-L1, CDX2, CD3, and CD8 was performed on tissue samples with representation of the invasive margin. PD-L1 expression in tumour cells and immune cells was reported conjointly. The expression of CD3 and CD8 was reported as a merged score based on the expression of both markers in the invasive margin and the tumour centre. Subsequently, a combined marker score was established based on all of the markers. Each marker added one point to the score when unfavourable immunohistochemical features was present, and the score was categorized as low, intermediate or high depending on the number of unfavourable stains. Hazard ratios for recurrence, disease-free survival and mortality were calculated.

Results

We included 188 patients undergoing colon cancer resections in 2011–2012. The median follow-up was 41.7 months, during which 41 (21.8%) patients had recurrence and 74 (39.4%) died. In multivariable regression analysis positive HLA-G expression (HR = 3.37, 95%CI [1.64–6.93]) was associated with higher recurrence rates, while a preserved CDX2 expression (HR = 0.23, 95%CI [0.06–0.85]) was associated with a lower risk of recurrence. An intermediate or high combined marker score was associated with increased recurrence rates (HR = 20.53, 95%CI [2.68–157.32] and HR = 7.56, 95%CI [1.06–54.16], respectively). Neither high expression of PD-L1 nor high CD3-CD8 score was significantly associated with recurrence rates. Patients with a high CD3-CD8 score had a significantly longer DFS and OS.

Conclusions

In tumour cells, expression of HLA-G and loss of CDX2 expression were associated with cancer recurrence. In addition, a combination of certain tumour tissue biomarkers was associated with colorectal cancer recurrence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09169-0.

Recent Updates on Mechanisms of Resistance to 5-Fluorouracil and Reversal Strategies in Colon Cancer Treatment

5-Fluorouracil (5-FU) plus leucovorin (LV) remain as the mainstay standard adjuvant chemotherapy treatment for early stage colon cancer, and the preferred first-line option for metastatic colon cancer patients in combination with oxaliplatin in FOLFOX, or irinotecan in FOLFIRI regimens. Despite treatment success to a certain extent, the incidence of chemotherapy failure attributed to chemotherapy resistance is still reported in many patients. This resistance, which can be defined by tumor tolerance against chemotherapy, either intrinsic or acquired, is primarily driven by the dysregulation of various components in distinct pathways. In recent years, it has been established that the incidence of 5-FU resistance, akin to multidrug resistance, can be attributed to the alterations in drug transport, evasion of apoptosis, changes in the cell cycle and DNA-damage repair machinery, regulation of autophagy, epithelial-to-mesenchymal transition, cancer stem cell involvement, tumor microenvironment interactions, miRNA dysregulations, epigenetic alterations, as well as redox imbalances. Certain resistance mechanisms that are 5-FU-specific have also been ascertained to include the upregulation of thymidylate synthase, dihydropyrimidine dehydrogenase, methylenetetrahydrofolate reductase, and the downregulation of thymidine phosphorylase. Indeed, the successful modulation of these mechanisms have been the game plan of numerous studies that had employed small molecule inhibitors, plant-based small molecules, and non-coding RNA regulators to effectively reverse 5-FU resistance in colon cancer cells. It is hoped that these studies would provide fundamental knowledge to further our understanding prior developing novel drugs in the near future that would synergistically work with 5-FU to potentiate its antitumor effects and improve the patient's overall survival.

PCGF1 promotes epigenetic activation of stemness markers and colorectal cancer stem cell enrichment

Colorectal cancer (CRC) stem cells are resistant to cancer therapy and are therefore responsible for tumour progression after conventional therapy fails. However, the molecular mechanisms underlying the maintenance of stemness are poorly understood. In this study, we identified PCGF1 as a crucial epigenetic regulator that sustains the stem cell-like phenotype of CRC. PCGF1 expression was increased in CRC and was significantly correlated with cancer progression and poor prognosis in CRC patients. PCGF1 knockdown inhibited CRC stem cell proliferation and CRC stem cell enrichment. Importantly, PCGF1 silencing impaired tumour growth in vivo. Mechanistically, PCGF1 bound to the promoters of CRC stem cell markers and activated their transcription by increasing the H3K4 histone trimethylation (H3K4me3) marks and decreasing the H3K27 histone trimethylation (H3K27me3) marks on their promoters by increasing expression of the H3K4me3 methyltransferase KMT2A and the H3K27me3 demethylase KDM6A. Our findings suggest that PCGF1 is a potential therapeutic target for CRC treatment.

Next-Generation Digital Histopathology of the Tumor Microenvironment

Progress in cancer research is substantially dependent on innovative technologies that permit a concerted analysis of the tumor microenvironment and the cellular phenotypes resulting from somatic mutations and post-translational modifications. In view of a large number of genes, multiplied by differential splicing as well as post-translational protein modifications, the ability to identify and quantify the actual phenotypes of individual cell populations in situ, i.e., in their tissue environment, has become a prerequisite for understanding tumorigenesis and cancer progression. The need for quantitative analyses has led to a renaissance of optical instruments and imaging techniques. With the emergence of precision medicine, automated analysis of a constantly increasing number of cellular markers and their measurement in spatial context have become increasingly necessary to understand the molecular mechanisms that lead to different pathways of disease progression in individual patients. In this review, we summarize the joint effort that academia and industry have undertaken to establish methods and protocols for molecular profiling and immunophenotyping of cancer tissues for next-generation digital histopathology-which is characterized by the use of whole-slide imaging (brightfield, widefield fluorescence, confocal, multispectral, and/or multiplexing technologies) combined with state-of-the-art image cytometry and advanced methods for machine and deep learning.

Tumour immune microenvironment biomarkers predicting cytotoxic chemotherapy efficacy in colorectal cancer

The role of the local tumour and stromal immune landscape is increasingly recognised to be important in cancer development, progression and response to therapy. The composition, function, spatial orientation and gene expression profile of the infiltrate of the innate and adaptive immune system at the tumour and surrounding tissue has an established prognostic role in colorectal cancer (CRC). Multiple studies have confirmed that a tumour immune microenvironment (TIME) reflective of a type 1 adaptive immune response is associated with improved prognosis. There have been significant efforts to evolve these observations into validated, histopathology-based prognostic biomarkers, such as the Immunoscore. However, the clinical need lies much more in the development of predictive, not prognostic, biomarkers which have the potential to improve patient outcomes. This is particularly pertinent to help guide cytotoxic chemotherapy use in CRC, which remains the standard of care. Cytotoxic chemotherapy has recognised immunomodulatory activity distinct from its antimitotic effects, including mechanisms such as immunogenic cell death (ICD) and induction/inhibition of key immune players. Response to chemotherapy may differ with regard to molecular subtype of CRC, which are strongly associated with immune phenotypes. Thus, immune markers are potentially useful, though under-reported, predictive biomarkers. In this review, we discuss the impact of the TIME on response to cytotoxic chemotherapy in CRC, with a focus on baseline immune markers, and associated genomic and transcriptomic signatures.

SOX2 Regulates lncRNA CCAT1/MicroRNA-185-3p/FOXP3 Axis to Affect the Proliferation and Self-Renewal of Cervical Cancer Stem Cells

It has been presented the role of long non-coding RNAs (lncRNAs) in cervical cancer (CC). We aim to discuss the effect of sex-determining region Y-box 2 (SOX2)/lncRNA colon cancer-associated transcript-1 (CCAT1)/microRNA-185-3p (miR-185-3p)/forkhead box protein 3 (FOXP3) on the proliferation and self-renewal ability of CC stem cells. MiR-185-3p, SOX2, CCAT1 and FOXP3 expressions were tested in CC tissues and cells. The relationship between SOX2/CCAT1 expression and clinicopathological features in CC patients was verified. Loss- and gain-of-function investigations were conducted in CD44⁺HeLa cells to discuss biological functions and self-renewal capacity. Finally, the relationships among SOX2, CCAT1, FOXP3 and miR-185-3p were verified. miR-185-3p expression was decreased, while SOX2, CCAT1 and FOXP3 expressions were increased in CC tissues and cells. SOX2 and CCAT1 expressions were linked to tumor size, lymph node metastasis and international federation of gynecology and obstetrics stage of CC. Down-regulating SOX2 or CCAT1 and up-regulating miR-185-3p resulted in inhibition of proliferation, invasion, migration and cell sphere number as well as apoptosis acceleration of CD44⁺HeLa cells. SOX2 could bind to CCAT1 which affected miR-185-3p expression, and FOXP3 was targeted by miR-185-3p.

A meta-analysis of CD274 (PD-L1) assessment and prognosis in colorectal cancer and its role in predicting response to anti-PD-1 therapy

BACKGROUND

PD-1 checkpoint inhibitors are novel therapeutic agents in colorectal cancer (CRC). Immunohistochemical staining for CD274 assessment is standardised in upper GI cancer, but not in CRC.

METHODS

Methodologies of relevant studies were scrutinized and meta-analysis of survival and CD274/PDCD1 performed. Furthermore, anti-PD-1 therapy clinical trial results in CRC were assessed with particular emphasis on CD274 assessment.

RESULTS

24 studies were included. CD274 on immune cells was associated with good prognosis. CD274 on tumour cells has heterogenous outcomes and does not meet requirements of a prognostic marker. As a marker of response to anti-PD-1 therapy, CD274 assessment is not standardised in CRC.

CONCLUSION

CD274 does not appear useful as a prognostic marker. As a marker of response to anti-PD-1 therapy, assessment methodology requires standardisation. As the Combined Positive Score (CPS) is used in upper GI cancer, this seems a logical method to adopt. Thresholds for CRC remain to be determined.

Cell softness regulates tumorigenicity and stemness of cancer cells

Identifying and sorting highly tumorigenic and metastatic tumor cells from a heterogeneous cell population is a daunting challenge. Here, we show that microfluidic devices can be used to sort marker‐based heterogeneous cancer stem cells (CSC) into mechanically stiff and soft subpopulations. The isolated soft tumor cells (< 400 Pa) but not the stiff ones (> 700 Pa) can form a tumor in immunocompetent mice with 100 cells per inoculation. Notably, only the soft, but not the stiff cells, isolated from CD133⁺, ALDH⁺, or side population CSCs, are able to form a tumor with only 100 cells in NOD‐SCID or immunocompetent mice. The Wnt signaling protein BCL9L is upregulated in soft tumor cells and regulates their stemness and tumorigenicity. Clinically, BCL9L expression is correlated with a worse prognosis. Our findings suggest that the intrinsic softness is a unique marker of highly tumorigenic and metastatic tumor cells.

Cancer Stem Cells-Origins and Biomarkers: Perspectives for Targeted Personalized Therapies

The use of biomarkers in diagnosis, therapy and prognosis has gained increasing interest over the last decades. In particular, the analysis of biomarkers in cancer patients within the pre- and post-therapeutic period is required to identify several types of cells, which carry a risk for a disease progression and subsequent post-therapeutic relapse. Cancer stem cells (CSCs) are a subpopulation of tumor cells that can drive tumor initiation and can cause relapses. At the time point of tumor initiation, CSCs originate from either differentiated cells or adult tissue resident stem cells. Due to their importance, several biomarkers that characterize CSCs have been identified and correlated to diagnosis, therapy and prognosis. However, CSCs have been shown to display a high plasticity, which changes their phenotypic and functional appearance. Such changes are induced by chemo- and radiotherapeutics as well as senescent tumor cells, which cause alterations in the tumor microenvironment. Induction of senescence causes tumor shrinkage by modulating an anti-tumorigenic environment in which tumor cells undergo growth arrest and immune cells are attracted. Besides these positive effects after therapy, senescence can also have negative effects displayed post-therapeutically. These unfavorable effects can directly promote cancer stemness by increasing CSC plasticity phenotypes, by activating stemness pathways in non-CSCs, as well as by promoting senescence escape and subsequent activation of stemness pathways. At the end, all these effects can lead to tumor relapse and metastasis. This review provides an overview of the most frequently used CSC markers and their implementation as biomarkers by focussing on deadliest solid (lung, stomach, liver, breast and colorectal cancers) and hematological (acute myeloid leukemia, chronic myeloid leukemia) cancers. Furthermore, it gives examples on how the CSC markers might be influenced by therapeutics, such as chemo- and radiotherapy, and the tumor microenvironment. It points out, that it is crucial to identify and monitor residual CSCs, senescent tumor cells, and the pro-tumorigenic senescence-associated secretory phenotype in a therapy follow-up using specific biomarkers. As a future perspective, a targeted immune-mediated strategy using chimeric antigen receptor based approaches for the removal of remaining chemotherapy-resistant cells as well as CSCs in a personalized therapeutic approach are discussed.

The Prognostic and Predictive Value of SOX2+ Cell Densities in Patients Treated for Colorectal Cancer

SOX2 (sex-determining region-Y homeobox-2) is a transcription factor essential for the maintenance of pluripotency and is also associated with stem-cell-like properties in preclinical cancer models. Our previous study on a cohort of stage III colon cancer patients demonstrated high SOX2⁺ cell densities were associated with poor prognosis. However, most patients were treated with adjuvant chemotherapy so the prognostic value of SOX2 could not be assessed independently from its value as a predictive marker for non-response to chemotherapy. This study aimed to assess whether SOX2 was a true prognostic marker or a marker for chemotherapy response in a historical cohort of patients, a high proportion of whom were chemotherapy-naïve. SOX2 immunostaining was performed on tissue micro-arrays containing tumor cores from 797 patients with stage II and III colorectal cancer. SOX2⁺ cell densities were then quantified with StrataQuest digital image analysis software. Overall survival was assessed using Kaplan-Meier estimates and Cox regression. It was found that high SOX2⁺ cell densities were not associated with poor overall survival. Furthermore, all patients had a significant improvement in survival after 5-fluorouracil (5-FU) treatment, irrespective of their SOX2⁺ cell density. Therefore, SOX2⁺ cell densities were not associated with prognosis or chemotherapy benefit in this study. This is in contrast to our previous study, in which most patients received oxaliplatin as part of their treatment, in addition to 5-FU. This suggests SOX2 may predict response to oxaliplatin treatment, but not 5-FU.

Combination of multiple tumor-infiltrating immune cells predicts clinical outcome in colon cancer

The infiltration of immune cells is highly associated with the development and progression of cancer. Thus, integrating the immune cell infiltrating profile into an immune cell infiltrating score may predict the survival of cancer patients. Here, by combining the infiltration proportion of 22 immune cells inferred from bulk tumor transcriptome of 879 patients, we identified an immune cell infiltrating indicator including five types of immune cells: resting T cells CD4 memory, macrophages M0-M2, and activated mast cells. The signature distinguished patients into two groups (high-risk and low-risk) with significantly different survival in the training cohort (HR = 1.96, 95% CI = 1.29-2.98, P = .0013) and two additional cohorts (HR = 1.78, 95%, CI = 1.16-2.75, P = .0079 and HR = 2.01, 95% CI = 1.28-3.14, P = .0019). The indicator remained as an independent prognostic factor after adjusting for clinicopathological factors by multivariable analysis in all cohorts. Stratification analysis showed that the signature consistently and significantly predicted survival of high-stage colon cancer patients in the training cohort (P = .00053) and validation cohorts (P = .017 and P = .0035). Moreover, we found that the low-risk patients were significantly correlated with deficient mismatch repair and the high-risk patients had a weak ability of trafficking of immune cells to tumors in the cancer immunity cycle. Overall, our results showed that integrating multiple tumor-infiltrating immune cells was an effective strategy for uncovering robust prognostic factor for tumor patients, and potentially was a promising response marker for precision oncology to be explored.

Clinical and Survival Impact of Sex-Determining Region Y-Box 2 in Colorectal Cancer: An Integrated Analysis of the Immunohistochemical Study and Bioinformatics Analysis

Transcription factor sex-determining region Y-box 2 (SOX2) involves in the maintenance of cancer stem cells. However, the role of SOX2 in colorectal cancer (CRC) remains unclear. This study was conducted to investigate the effect of SOX2 on CRC. Studies were searched using electronic databases. The combined odds ratios (ORs) or hazard ratios (HRs: multivariate Cox survival analysis) with their 95% confidence intervals (CIs) were calculated. The Cancer Genome Atlas (TCGA) and GEO datasets were further applied to validate the survival effect. The functional analysis of SOX2 was investigated. In this work, 13 studies including 2337 patients were identified, and validation data were enrolled from TCGA and GEO datasets. SOX2 expression was not significantly related to age, gender, microsatellite instability (MSI) status, clinical stage, histological grade, tumor size, pT-stage, lymph node metastasis, distal metastasis, and cancer-specific survival (CSS) but was correlated with worse overall survival (OS: n = 536 patients) (P < 0.05). Furthermore, TCGA data demonstrated similar results, with no significant correlation between SOX2 and pathological characteristics. Further validation data (OS: n = 1408 and disease-free survival (DFS): n = 1367) showed that SOX2 expression was correlated with worse OS (HR = 1.35, 95% CI: 1.11–1.65, P=0.004) and DFS (HR = 1.30, 95% CI: 1.04–1.62, P=0.02). The functional analyses showed that SOX2 involved in cell-cell junction, focal adhesion, extracellular matrix- (ECM-) receptor interaction, and MAP kinase activity. Our findings suggest that SOX2 expression may be correlated with the worse prognosis of CRC.

Clinical implications of cancer stem cells in digestive cancers: acquisition of stemness and prognostic impact

Digestive system cancers are the most frequent cancers worldwide and often associated with poor prognosis because of their invasive and metastatic characteristics. Recent studies have found that the plasticity of cancer cells can impart cancer stem-like properties via the epithelial-mesenchymal transition (EMT). Cancer stem-like properties such as tumor initiation are integral to the formation of metastasis, which is the main cause of poor prognosis. Numerous markers of cancer stem cells (CSCs) have been identified in many types of cancer. Therefore, CSCs, via their stem cell-like functions, may play an important role in prognosis after surgery. While several reports have described prognostic analysis using CSC markers, few reviews have summarized CSCs and their association with prognosis. Herein, we review the prognostic potential of eight CSC markers, CD133, CD44, CD90, ALDH1A1, EPCAM, SOX2, SOX9, and LGR5, in digestive cancers including those of the pancreas, colon, liver, gastric, and esophagus.

Expression Profiles of the Phosphatase and Tensin Homolog (PTEN), CDH1, and CDH2 Genes, and the Cell Membrane Protein, CD133, in the Ishikawa Human Endometrial Adenocarcinoma Cell Line

Background

This study aimed to investigate the expression profile of the phosphatase and tensin homolog (PTEN) gene, the cadherin genes, CDH1 and CDH2, and the cell membrane glycoprotein, CD133, in the Ishikawa human endometrial adenocarcinoma cell line.

Material/Methods

The Ishikawa endometrial carcinoma cell groups included cells transfected with the pLVX-puro lentiviral expression vector (the Ishikawa-puro group) and cells transfected with the pLVX-puro-PTEN lentiviral expression vector (the Ishikawa-PTEN group). The mRNA expression of the cadherin genes, CDH1 and CDH2, was detected by quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The expression levels of the transmembrane glycoprotein CD133, a cancer stem cell marker, was detected by flow cytometry.

Results

The expression of CDH1 and CDH2 mRNA in the Ishikawa-PTEN cells was lower than in the control cells. CD133 expression was lower in the Ishikawa-PTEN cells compared with the control cells.

Conclusions

This in vitro study showed that in Ishikawa endometrial carcinoma cells, downregulation of PTEN was associated with the expression of the CDH1 and CDH2 genes and upregulated expression of the cell membrane glycoprotein, CD133, which are associated with epithelial-mesenchymal transition (EMT) in malignancy. These findings support the need for further studies to investigate the potential role of PTEN in invasion and metastasis in endometrial carcinoma.

The local inflammatory response in colorectal cancer - Type, location or density? A systematic review and meta-analysis

INTRODUCTION

The host anti-tumour inflammatory response is a strong prognostic indicator, and tumour infiltrating lymphocytes (TILs) are believed to have a complimentary role alongside TNM assessment in dictating future management. However, there is wide disagreement regarding the most efficacious and cost-effective method of assessment.

METHODS

A comprehensive literature search was performed of EMBASE, MedLine and PubMed as well as an assessment of references to identify all relevant studies relating to the assessment of the peri-tumoural inflammatory response or TILs and prognosis in colorectal cancer (CRC). A meta-analysis was performed of 67 studies meeting the REMARK criteria using RevMan software.

RESULTS

Intratumoural assessment of both CD3 and CD8 in CRC were significant for disease-free survival (DFS) (combined HRs 0.46; 95%CI: 0.39-0.54 and 0.54; 95%CI: 0.45-0.65), as well as overall survival (OS) and disease-specific survival (DSS). The same was true for assessment of CD3 and CD8 at the invasive margin (DFS: combined HRs 0.45; 95%CI: 0.33-0.61 and 0.51; 95%CI: 0.41-0.62). However, similar fixed effects summaries were also observed for H&E-based methods, like Klintrup-Makinen grade (DFS: HR 0.62; 95%CI: 0.43-0.88). Furthermore, inflammatory assessments were independent of MSI status.

CONCLUSION

The evidence suggests that it is the density of a co-ordinated local inflammatory infiltrate that confers survival benefit, rather than any individual immune cell subtype. Furthermore, the location of individual cells within the tumour microenvironment does not appear to influence survival. The authors advocate a standardised assessment of the local inflammatory response, but caution against emphasizing the importance of any individual immune cell subtype.

The association of SOX2 with clinical features and prognosis in colorectal cancer: A meta-analysis

OBJECTIVES

The expression of SOX2 protein has been reported to be correlated with colorectal cancers. In this study, we conducted a meta-analysis to evaluate the association of SOX2 with clinical features and prognosis in colorectal cancer.

METHODS

The relevant studies up to March 2019 were searched in Two English databases(PubMed and EMBASE)and two Chinese databases (CNKI and Wanfang database). Pooled ORs or HRs were used to assess the strength of the association between SOX2 and clinical parameters.

RESULTS

14 studies involving 2077 colorectal cancer patients were included in the meta-analysis. Our results revealed there were no associations between SOX2 and gender and age. However, significant positive associations were observed for N categories (OR = 3.02, 95 %CI = 2.11-4.31), advanced stage (OR = 2.85, 95 %CI = 2.00-4.07), poor differentiation (OR = 1.90, 95 %CI = 1.38-2.64), distant metastasis (OR = 4.66, 95 %CI = 2.77-7.85) and poor OS (HR = 1.49, 95 %CI = 1.09-2.03).

CONCLUSION

The results indicated that SOX2 protein may serve as a novel prognostic factor for patients with colorectal cancer.

microRNA-95 knockdown inhibits epithelial-mesenchymal transition and cancer stem cell phenotype in gastric cancer cells through MAPK pathway by upregulating DUSP5

This study investigated the role of microRNA-95 (miR-95) in gastric cancer (GC) and to elucidate the underlying mechanism. Initially, bioinformatic prediction was used to predict the differentially expressed genes and related miRNAs in GC. miR-95 and DUSP5 expression was altered in GC cell line (MGC803) to evaluate their respective effects on the epithelial-mesenchymal transition (EMT) process, cellular processes (cell proliferation, migration, invasion, cell cycle, and apoptosis), cancer stem cell (CSC) phenotype, as well as tumor growth ability. It was further predicted in bioinformatic prediction and verified in GC tissue and cell line experiments that miR-95 was highly expressed in GC. miR-95 negatively regulated DUSP5, which resulted in the MAPK pathway activation. Inhibited miR-95 or overexpressed DUSP5 was observed to inhibit the levels of CSC markers (CD133, CD44, ALDH1, and Lgr5), highlighting the inhibitory role in the CSC phenotype. More important, evidence was obtained demonstrating that miR-95 knockdown or DUSP5 upregulation exerted an inhibitory effect on the EMT process, cellular processes, and tumor growth. Together these results, miR-95 knockdown inhibited GC development via DUSP5-dependent MAPK pathway.

Identification of Transcriptional Signatures of Colon Tumor Stroma by a Meta-Analysis

Background

The tumor stroma plays pivotal roles in influencing tumor growth, invasion, and metastasis. Transcriptional signatures of colon tumor stroma (CTS) are significantly associated with prognosis of colon cancer. Thus, identification of the CTS transcriptional features could be useful for colon cancer diagnosis and therapy.

Methods

By a meta-analysis of three CTS gene expression profiles datasets, we identified differentially expressed genes (DEGs) between CTS and colon normal stroma. Furthermore, we identified the pathways, upstream regulators, and protein-protein interaction (PPI) network that were significantly associated with the DEGs. Moreover, we analyzed the enrichment levels of immune signatures in CTS. Finally, we identified CTS-associated gene signatures whose expression was significantly associated with prognosis in colon cancer.

Results

We identified numerous significantly upregulated genes (such as CTHRC1, NFE2L3, SULF1, SOX9, ENC1, and CCND1) and significantly downregulated genes (such as MYOT, ASPA, KIAA2022, ARHGEF37, BCL-2, and PPARGC1A) in CTS versus colon normal stroma. Furthermore, we identified significantly upregulated pathways in CTS that were mainly involved in cellular development, immune regulation, and metabolism, as well as significantly downregulated pathways in CTS that were mostly metabolism-related. Moreover, we identified upstream TFs (such as SUZ12, NFE2L2, RUNX1, STAT3, and SOX2), kinases (such as MAPK14, CSNK2A1, CDK1, CDK2, and CDK4), and master metabolic transcriptional regulators (MMTRs) (such as HNF1A, NFKB1, ZBTB7A, GATA2, and GATA5) regulating the DEGs. We found that CD8+ T cells were more enriched in CTS than in colon normal stroma. Interestingly, we found that many of the DEGs and their regulators were prognostic markers for colon cancer, including CEBPB, PPARGC1, STAT3, MTOR, BCL2, JAK2, and CDK1.

Conclusions

The identification of CTS-specific transcriptional signatures may provide insights into the tumor microenvironment that mediates the development of colon cancer and has potential clinical implications for colon cancer diagnosis and treatment.

Recent Advances in Cancer Stem Cell-Targeted Immunotherapy

Cancer stem cells (CSCs) are one of the reasons for the relapse of cancer cells and metastasis. They have drug resistance against most chemotherapeutic agents. CSCs are also responsible for tumor cell heterogeneity and cause minimal residual disease. In order to achieve complete regression of tumors, CSCs have to be targeted. Recent advances in immunotherapies have shown promising outcomes in curing cancer, which are also applicable to target CSCs. CSCs express immune markers and exhibit specific immune characteristics in various cancers, which can be used in immunotherapies to target CSCs in the tumor microenvironment. Recently, various strategies have been used to target CSCs. Adaptive T-cells, dendritic cell (DC)-based vaccines, oncolytic viruses, immune checkpoint inhibitors, and combination therapies are now being used to target CSCs. Here, we discuss the feasibility of these immunological approaches and the recent trends in immunotherapies to target CSCs.

Clinicopathological and prognostic significance of PD-L1 expression in colorectal cancer: a systematic review and meta-analysis

OBJECTIVE

To analyze the prognostic value of programmed death factor ligand 1 (PD-L1) in colorectal cancer.

METHODS

Electronic databases, such as PubMed, Web of Science, Embase, and Cochrane library, were searched to identify studies evaluating the PD-L1 expression and overall survival (OS) in these patients. Afterwards, the relevant data were extracted to perform the meta-analysis.

RESULTS

A total of 3481 patients were included in 10 studies. The combined hazard ratio (HR) was 1.22 (95%CI = 1.01-1.48, P = 0.04), indicating that high expression of PD-L1 was significantly correlated with poor prognosis of colorectal cancer. Apropos of clinicopathological features, the merged odds ratio (OR) exhibited that highly expressed PD-L1 was firmly related to lymphatic invasion (OR = 3.49, 95%CI = 1.54-7.90, P = 0.003) and advanced stage (OR = 1.77, 95%CI = 1.41-2.23, P < 0.00001), but not correlative with patients' gender, microsatellite instability, or tumor location.

CONCLUSION

The expression of PD-L1 can be utilized as an independent factor in judging the prognosis of colorectal cancer, and patients with advanced cancer or lymphatic invasion are more likely to express PD-L1. This conclusion may lay a theoretical foundation for the application of PD-1/PD-L1 immunoassay point inhibitors but still needs verifying by sizeable well-designed cohort studies.

Epidermal growth factor induces STAT1 expression to exacerbate the IFNr-mediated PD-L1 axis in epidermal growth factor receptor-positive cancers

The epidermal growth factor (EGF) receptor (EGFR) overexpressed in many cancers, including lung and head and neck cancers, and is involved in cancer cell progression and survival. PD-L1, increases in tumor cells to evade and inhibit CD8+ T cells, is a clinical immunotherapeutic target. This study investigated the molecular mechanism of EGF on regulating PD-L1 in EGFR-positive cancers and determined potential agents to reduce PD-L1 expression. RNA sequencing (RNAseq) and bioinformatics analysis were performed to determine potential driver genes that regulate PD-L1 in tumor cells-derived tumorspheres which mimicking cancer stem cells. Then, the specific inhibitors targeting EGFR were applied to reduce the expression of PD-L1 in vitro and in vivo. We validated that EGF could induce PD-L1 expression in the selected EGFR-positive cancers. RNAseq results revealed that STAT1 increased as a driver gene in KOSC-3-derived tumorspheres; these data were analyzed using PANTHER followed by NetworkAnalyst. The blockade of EGFR by afatinib resulted in decreased STAT1 and IRF-1 levels, both are transcriptional factors of PD-L1, and disabled the IFNr-STAT1-mediated PD-L1 axis in vitro and in vivo. Moreover, STAT1 knockdown significantly reduced EGF-mediated PD-L1 expression, and ruxolitinib, a JAK1/JAK2 inhibitor, significantly inhibited STAT1 phosphorylation to reduce the IFNr-mediated PD-L1 axis. These results indicate that EGF exacerbates PD-L1 by increasing the protein levels of STAT1 to enforce the IFNr-JAK1/2-mediated signaling axis in selected EGFR-positive cancers. The inhibition of EGFR by afatinib significantly reduced PD-L1 and may be a potential strategy for enhancing immunotherapeutic efficacy.

Immunological environment in colorectal cancer: a computer-aided morphometric study of whole slide digital images derived from tissue microarray

Cancer research has moved from investigating tumour cells to including analysis of the tumour microenvironment as well. The aim of this study was to assess the cellular infiltrate of colorectal cancer (CRC) using computer-aided analysis of whole slide digital image derived from tissue microarray (TMA). TMA slides from 31 CRC patients were immunostained for forkhead box protein 3 (FOXP3) and immunomodulatory enzyme indoleamine 2,3-dioxygenase (IDO) at four sites: centre (C) and invasive front (F) of the tumour, proximal non-metastatic draining lymph node (N-), tumour-draining lymph node with metastasis (N+) and healthy mucosa at 10 cm from the cancer (M). We analysed the proportion of IDO+ tissue areas in the lamina propria or in the non-epithelial area of the lymph node and in epithelial cells in each site. The normal mucosa of patients operated on for benign disease was also analysed. The proportion (%) of FOXP3+ tissue area in C, F, N-, N+ and M were 2.3 ± 1.8, 2.6 ± 2.9, 6.0 ± 2.9, 14.2 ± 5.8 and 1.2 ± 0.8 (p < 0.001). The proportion (%) of IDO+ tissue area in the lamina propria of C, F, N-, N+ and M were 1.6 ± 3.1, 1.1 ± 1.3, 3.4 ± 2.5, 9.1 ± 8.5 and 6.7 ± 5.4 (p < 0.001). IDO+ tissue area in the lamina propria was not significantly different between healthy mucosa of patients with cancer than without (1.8 ± 3 vs 1.1 ± 0.95). The proportion of IDO positive tissue area in the epithelium was significantly higher in healthy mucosa of patients with cancer than without (5.4 ± 13.8 vs 2.1 ± 2.4). The FOXP3+ tissue area was increased in healthy mucosa of CRC patients in comparison with healthy mucosa of patients with colorectal resection for disease other than cancer: 1.20 ± 1.81 versus 0.81 ± 0.51 (p < 0.05). The proportion of IDO+ tissue area in lymph node (N-) was correlated with the proportion of FOXP3+ tissue area in tumour area (r = 0.44, p < 0.01). TMA technique permits simultaneous analysis of FOXP3+ and IDO+ cells at different sites including tumour, draining non-metastatic lymph node, metastatic lymph node and normal mucosa.

The role of immune microenvironment in small-cell lung cancer: Distribution of PD-L1 expression and prognostic role of FOXP3-positive tumour infiltrating lymphocytes

INTRODUCTION

The prognosis of small-cell lung cancer (SCLC) is dismal and new effective therapies are needed. Immunotherapy looks promising, but no molecular predictive markers are currently available, and data on immune microenvironment are very limited.

METHODS

We retrospectively analysed 104 SCLC cases. Immunohistochemistry evaluation of PD-L1 was performed both on tumour cells (TCs) and on tumour-infiltrating immune cells (TIICs) by using anti-PD-L1 22C3 antibody (DAKO) and categorised by using 1% as cut-off point. Tumour-infiltrating lymphocytes (TILs) were characterised by using anti-CD8 and anti-FOXP3 antibodies. Semi-quantitative score was used and categorised as positive versus negative/low. The relation of molecular markers with prognosis and with clinical variables was evaluated.

RESULTS

The analysis included 66 stage I-III patients (48 surgically resected, 18 treated with radical-intent chemoradiotherapy) and 38 metastatic cases. In the overall study population, PD-L1 was expressed on TCs and TIICs in 25% and 40% of cases, respectively. The proportion of PD-L1-positive cases was significantly higher in stage I-III versus metastatic patients (32% versus 13%, p: 0.034 for TCs; 51.5% versus 21% for TIICs, p: 0.002). CD8- and FOXP3-positive TILs were present in 59% and 72% of samples, respectively. The presence of FOXP3-TILs was associated with improved prognosis among non-metastatic patients, with a hazard ratio for survival of 0.32 (95% confidence interval [CI]: 0.16-0.7, p: 0.006) for univariate analysis, and 0.37 (95% CI: 0.17-0.81, p: 0.013) for multivariate analysis.

CONCLUSIONS

Immune contexture of SCLC may differ according to stage. The presence of FOXP3-positive TILs is a potential prognostic marker for stage I-III SCLCs and warrants further investigation.

Jade family PHD finger 3 (JADE3) increases cancer stem cell-like properties and tumorigenicity in colon cancer

Jade family PHD finger 3 (JADE3) plays a role in inducing histone acetylation during transcription, and is involved in the progression of several human cancers; however, its role in colon cancer remains unclear. Herein, we found that JADE3 was markedly upregulated in colon cancer tissues and significantly correlated with cancer progression, and predicted shorter patient survival. Further, JADE3 was expressed much higher in colon cancer cell lines that are enriched with a stem-like signature. Overexpression of JADE3 increased, while silencing JADE3 reduced cancer stem cell-like traits in colon cancer cells in vitro and in vivo. Importantly, silencing of JADE3 strongly impaired the tumor initiating capacity of colon cancer cells in vivo. Furthermore, JADE3 interacted with the promoters of colon stem cell marker LGR5 and activated its transcription, by increasing the occupancy of p300 acetyltransferase and histone acetylation on the promoters. Finally, we found that JADE3 expression was substantially induced by Wnt/β-catenin signaling. These findings suggest an oncogenic role of JADE3 by regulating cancer stem cell-like traits in the colon cancer, and therefore JADE3 might be a potential therapeutic target for the treatment of colon cancer.

Colorectal cancer: genetic abnormalities, tumor progression, tumor heterogeneity, clonal evolution and tumor-initiating cells

Colon cancer is the third most common cancer worldwide. Most colorectal cancer occurrences are sporadic, not related to genetic predisposition or family history; however, 20-30% of patients with colorectal cancer have a family history of colorectal cancer and 5% of these tumors arise in the setting of a Mendelian inheritance syndrome. In many patients, the development of a colorectal cancer is preceded by a benign neoplastic lesion: either an adenomatous polyp or a serrated polyp. Studies carried out in the last years have characterized the main molecular alterations occurring in colorectal cancers, showing that the tumor of each patient displays from two to eight driver mutations. The ensemble of molecular studies, including gene expression studies, has led to two proposed classifications of colorectal cancers, with the identification of four/five non-overlapping groups. The homeostasis of the rapidly renewing intestinal epithelium is ensured by few stem cells present at the level of the base of intestinal crypts. Various experimental evidence suggests that colorectal cancers may derive from the malignant transformation of intestinal stem cells or of intestinal cells that acquire stem cell properties following malignant transformation. Colon cancer stem cells seem to be involved in tumor chemoresistance, radioresistance and relapse.