Clinical significance of CD133 and hypoxia inducible factor-1α gene expression in rectal cancer after preoperative chemoradiotherapy

Hypoxia-Inducible Factor-Dependent and Independent Mechanisms Underlying Chemoresistance of Hypoxic Cancer Cells

In hypoxic regions of malignant solid tumors, cancer cells acquire resistance to conventional therapies, such as chemotherapy and radiotherapy, causing poor prognosis in patients with cancer. It is widely recognized that some of the key genes behind this are hypoxia-inducible transcription factors, e.g., hypoxia-inducible factor 1 (HIF-1). Since HIF-1 activity is suppressed by two representative 2-oxoglutarate-dependent dioxygenases (2-OGDDs), PHDs (prolyl-4-hydroxylases), and FIH-1 (factor inhibiting hypoxia-inducible factor 1), the inactivation of 2-OGDD has been associated with cancer therapy resistance by the activation of HIF-1. Recent studies have also revealed the importance of hypoxia-responsive mechanisms independent of HIF-1 and its isoforms (collectively, HIFs). In this article, we collate the accumulated knowledge of HIF-1-dependent and independent mechanisms responsible for resistance of hypoxic cancer cells to anticancer drugs and briefly discuss the interplay between hypoxia responses, like EMT and UPR, and chemoresistance. In addition, we introduce a novel HIF-independent mechanism, which is epigenetically mediated by an acetylated histone reader protein, ATAD2, which we recently clarified.

Emerging agents that target signaling pathways to eradicate colorectal cancer stem cells

Colorectal cancer (CRC) represents the third most commonly diagnosed cancer and the second leading cause of cancer death worldwide. The modern concept of cancer biology indicates that cancer is formed of a small population of cells called cancer stem cells (CSCs), which present both pluripotency and self-renewal properties. These cells are considered responsible for the progression of the disease, recurrence and tumor resistance. Interestingly, some cell signaling pathways participate in CRC survival, proliferation, and self-renewal properties, and most of them are dysregulated in CSCs, including the Wingless (Wnt)/β-catenin, Notch, Hedgehog, nuclear factor kappa B (NF-κB), Janus kinase/signal transducer and activator of transcription (JAK/STAT), peroxisome proliferator-activated receptor (PPAR), phosphatidyl-inositol-3-kinase/Akt/mechanistic target of rapamycin (PI3K/Akt/mTOR), and transforming growth factor-β (TGF-β)/Smad pathways. In this review, we summarize the strategies for eradicating CRC stem cells by modulating these dysregulated pathways, which will contribute to the study of potential therapeutic schemes, combining conventional drugs with CSC-targeting drugs, and allowing better cure rates in anti-CRC therapy.

Personalized medicine: Stem cells in colorectal cancer treatment

Treatment failure in primary as well as metastatic cancer patients, caused by chemo and radioresistance, has reinforced the research for the applicability of personalized medicine. The use of stem cells (SCs) and cancer stem cells (CSCs) in such a treatment approach will be reviewed in this study. Colorectal cancer (CRC) SCs prove to be a promising asset for CRC treatment optimization both by serving as biomarkers for the current therapy modalities, by means of treatment personalization and patient/tumor stratification, as well as in the development of targeted therapies, selective for the stem cell population. Similar conclusions are drawn, regarding mesenchymal stromal cells (MSCs) and their effect in CRC therapy; while resident stromal cells (RSCs) of tumor microenvironment (TME) seem to promote the tumorigenic and metastatic processes in addition to conferring to the chemo- and radioresistance, under certain conditions they are able to improve the treatment outcome of CRC chemotherapy, e.g. by targeted enzyme/prodrug treatment of CRC cells. This review, points out the dynamic potential of CSCs and other SCs types in CRC treatment personalization as well as, in the improvement of current treatment approaches, opting to a higher therapeutic rate, improved prognosis, survival and quality of life for CRC patients.

PROM1 and PROM2 expression differentially modulates clinical prognosis of cancer: a multiomics analysis

Prominin 1 (PROM1) is considered a biomarker for cancer stem cells, although its biological role is unclear. Prominin 2 (PROM2) has also been associated with certain cancers. However, the prognostic value of PROM1 and PROM2 in cancer is controversial. Here, we performed a systematic data analysis to examine whether prominins can function as prognostic markers in human cancers. The expression of prominins was assessed and their prognostic value in human cancers was determined using univariate and multivariate survival analyses, via various online platforms. We selected a group of prominent functional protein partners of prominins by protein-protein interaction analysis. Subsequently, we investigated the relationship between mutations and copy number alterations in prominin genes and various types of cancers. Furthermore, we identified genes that correlated with PROM1 and PROM2 in certain cancers, based on their levels of expression. Gene ontology and pathway analyses were performed to assess the effect of these correlated genes on various cancers. We observed that PROM1 was frequently overexpressed in esophageal, liver, and ovarian cancers and its expression was negatively associated with prognosis, whereas PROM2 overexpression was associated with poor overall survival in lung and ovarian cancers. Based on the varying characteristics of prominins, we conclude that PROM1 and PROM2 expression differentially modulates the clinical outcomes of cancers.

CD133: An emerging prognostic factor and therapeutic target in colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of death worldwide. Recently, the role of cancer stem cells (CSCs) has been highlighted as a crucial emerging factor in chemoresistance, cancer relapse, and metastasis. CD133 is a surface marker of CSCs and has been argued to have prognostic and therapeutic values in CRC along with its related pathways such as Wnt, Notch, and hedgehog. Several studies have successfully applied targeted therapies against CD133 in CRC models namely bispecific antibodies (BiAbs) and anti-Wnt and notch pathways agents. These studies have yielded initial promising results in this regard. However, none of the therapeutics have been used in the clinical setting and their efficacy and adverse effects profile are yet to be elucidated. This review aims to gather the old and most recent data on the prognostic and therapeutic values of CD133 and CD133-targeted therapies in CRC.

Leucine-rich repeat-containing G protein-coupled receptor 5 and CD133 expression is associated with tumor progression and resistance to preoperative chemoradiotherapy in low rectal cancer

Preoperative chemoradiotherapy has been performed as a standard therapy for advanced low rectal cancer. Cancer stem cells (CSCs) have been reported to contribute to resistance to treatment and patient prognosis. Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) and cluster of differentiation (CD133) are putative markers for CSCs. However, their prognostic ability remains unknown, and evaluation of a single marker can be insufficient due to the heterogeneity of cancer. LGR5 and CD133 expression was immunohistochemically evaluated in surgical specimens of 56 patients who received curative resection following chemoradiotherapy for advanced low rectal cancer. In addition, the correlations between their expression levels, and clinicopathological features and patient prognosis were asessed. LGR5 expression was significantly correlated with lymphatic invasion, lymph node metastasis, and tumor node metastasic (TNM) stage. CD133 expression was significantly correlated with vascular invasion and the tumor regression grade. Combined expression was significantly correlated with lymphatic invasion, tumor regression grade and TNM stage, but not with overall, and disease-free survival. LGR5 and CD133 expressions may represent useful markers associated with tumor progression and resistance to chemoradiotherapy in patients with low rectal cancer. Furthermore, combined expression of these markers may be a more useful marker compared with the expression of each single marker.

Predictive and prognostic biomarkers for neoadjuvant chemoradiotherapy in locally advanced rectal cancer

Locally advanced rectal cancer is regularly treated with trimodality therapy consisting of neoadjuvant chemoradiation, surgery and adjuvant chemotherapy. There is a need for biomarkers to assess treatment response, and aid in stratification of patient risk to adapt and personalise components of the therapy. Currently, pathological stage and tumour regression grade are used to assess response. Experimental markers include proteins involved in cell proliferation, apoptosis, angiogenesis, the epithelial to mesenchymal transition and microsatellite instability. As yet, no single marker is sufficiently robust to have clinical utility. Microarrays that screen a tumour for multiple promising candidate markers, gene expression and microRNA profiling will likely have higher yield and it is expected that a combination or panel of markers would prove most useful. Moving forward, utilising serial samples of circulating tumour cells or circulating nucleic acids can potentially allow us to demonstrate tumour heterogeneity, document mutational changes and subsequently measure treatment response.

Prognostic value of CD133 expression in cancer patients treated with chemoradiotherapy: a meta-analysis

Many studies evaluated the correlations of CD133 expression with the clinical outcomes in patients treated with chemoradiotherapy (CRT) but yielded controversial results. This meta-analysis was performed to identify the impacts of CD133 expression on the prognosis of cancer patients treated with CRT. Electronic databases updated up to March 2014 were searched to find relevant studies. Relevant literatures without any language restrictions were searched via electronic databases as follows: Web of Science (1945 ~ 2013), the Cochrane Library Database (Issue 12, 2013), PubMed (1966 ~ 2013), EMBASE (1980 ~ 2013), CINAHL (1982 ~ 2013), and the Chinese Biomedical Database (CBM) (1982 ~ 2013). STATA software was used for the current meta-analysis. Hazard ratios (HR) and its corresponding 95% confidence interval (95% CI) were calculated. Six studies were identified with a total of 470 cancer patients treated with CRT. The meta-analysis results showed that CD133-positive patients had poorer overall survival (OS) than that of CD133-negative patients (HR = 2.13, 95% CI = 1.20 ~ 3.07, P < 0.001). Furthermore, CD133-positive patients displayed shorter disease-free survival (DFS) than that of CD133-negative patients (HR = 1.74, 95% CI = 0.08 ~ 3.40, P = 0.039). Ethnicity-stratified analysis indicated that CD133 expression positively correlated with shorter OS among the Japanese, Chinese, and Spanish populations (all P < 0.05). In conclusion, our findings suggest that CD133 expression may be positively correlated with poorer prognosis in cancer patients treated with CRT.

Physical lysis only (PLO) methods suitable as rapid sample pretreatment for qPCR assay

Quantitative PCR (qPCR) enables rapid and sensitive gene quantification and is widely used in genomics, such as biological, medical, environmental, and food sciences. However, sample pretreatment requires the use of conventional DNA extraction kits which are time-consuming and labor intensive. In this study, we investigated four physical lysis only (PLO) methods which are rapid and could serve as alternatives to conventional DNA extraction kits. These PLO methods are bead mill, heating, sonication, and freeze-thaw. Using ethidium bromide-based assay, their performance was evaluated and compared. The effects of cell debris and its removal were also investigated. Bead mill method without cell debris removal appeared to yield the best qPCR results among the four PLO methods. In addition, bead mill method also performed better than conventional DNA extraction kits. It is probably due to the substantial loss of DNA material during the extensive purification of the conventional DNA extraction kits. The bead mill method has been demonstrated to successfully quantify 10(2) to 10(7) copies of the PAH-RHDα gene of Pseudomonas putida.

P21 and CD166 as predictive markers of poor response and outcome after fluorouracil-based chemoradiotherapy for the patients with rectal cancer

Background

Pre-operative chemoradiotherapy (CRT) is the standard treatment in clinical stage T3/4 or node positive rectal cancer. However, there are no established biomarkers that can predict the pathological response and clinical outcome to CRT.

Methods

Immunohistochemical staining was performed in tissue arrays constructed from core tissue specimens taken before treatment and from operative specimens from 112 patients who received 5-FU based pre-operative CRT and surgery. Expression of Ki67, TS, BAX, EpCAM, p53, p21, EGFR, CD44, CD133, CD166, HIF1α and ALDH1 were assessed and correlated with tumor regression grades and disease free survival.

Results

Of the 112 patients (M/F 74/38, median age: 62), 20 (17.9%) patients achieved pathologic complete remission (pCR). In analyzing the associations between marker expressions and tumor regression grades, high p21 expression at the pretreatment biopsy was significantly associated with non-pCR (p = 0.022) and poor disease free survival (median DFS - low vs high p21: 75.8 vs 58.1 months, p = 0.002). In the multivariate analysis, high p21 expression level at the pre-treatment biopsy was significantly associated with poor DFS (p = 0.001, HR 6.14; 95% CI 2.03, 18.55). High CD166 expression level at the pretreatment biopsy was also associated with poor DFS (p = 0.003; HR 5.61; 95% CI 1.81, 17.35).

Conclusion

These show high p21 and CD166 expression at the pretreatment biopsy were associated with tumor regression and poor prognosis in patients treated with 5-FU based CRT. Larger, prospective and functional studies are warranted to determine the role of p21 and CD166 as predictive biomarker of response to CRT.

A comparison of laparoscopic and open surgery following pre-operative chemoradiation therapy for locally advanced lower rectal cancer

OBJECTIVE

Although pre-operative chemoradiation therapy for advanced lower rectal cancer is a controversial treatment modality, it is increasingly used in combination with surgery. Few studies have considered the combination of chemoradiation therapy followed by laparoscopic surgery for locally advanced lower rectal cancer; therefore, this study aimed to assess the usefulness of this therapeutic combination.

METHODS

We retrospectively reviewed the medical records of patients with locally advanced lower rectal cancer treated by pre-operative chemoradiation therapy and surgery from February 2002 to November 2012 at Oita University. We divided patients into an open surgery group and a laparoscopic surgery group and evaluated various parameters by univariate and multivariate analyses.

RESULTS

In total, 33 patients were enrolled (open surgery group, n = 14; laparoscopic surgery group, n = 19). Univariate analysis revealed that compared with the open surgery group, operative time was significantly longer, whereas intra--operative blood loss and intra-operative blood transfusion requirements were significantly less in the laparoscopic surgery group. There were no significant differences in post-operative complication and recurrence rates between the two groups. According to multivariate analysis, operative time and intra-operative blood loss were significant predictors of outcome in the laparoscopic surgery group.

CONCLUSIONS

This study suggests that laparoscopic surgery after chemoradiation therapy for locally advanced lower rectal cancer is a safe procedure. Further prospective investigation of the long-term oncological outcomes of laparoscopic surgery after chemoradiation therapy for locally advanced lower rectal cancer is required to confirm the advantages of laparoscopic surgery over open surgery.

Expression of the cancer stem cell markers CD44v6 and ABCG2 in tongue cancer: effect of neoadjuvant chemotherapy on local recurrence

The efficacy of neoadjuvant chemotherapy (NAC) is controversial, and no report supports NAC with a high evidence level. Recently, we showed that a deep surgical margin was resected very close to the tumor site in many NAC-treated oral squamous cell carcinoma patients, suggesting that NAC may lead to local recurrence and poor outcomes. The purpose of this study was to evaluate the effect of NAC on tumor local recurrence using cancer stem cell marker immunohistochemistry. We retrospectively analyzed 89 patients who underwent radical surgery for tongue cancer, and examined the effect of NAC on tumor local recurrence. Cancer stem cell marker (CD44v6 and ABCG2) expression was detected by immunohistochemistry. In our study, the local recurrence rate was 12.4%. CD44v6 and ABCG2 expression was significantly associated with regional lymph node metastasis, pattern of invasion, depth of invasion, perineural invasion and local recurrence, respectively. Tumor local recurrence was a significant independent predictive factor of the 5-year disease specific survival. CD44v6 or ABCG2 positivity in NAC-treated patients was significantly associated with tumor local recurrence. It was suggested that local recurrence in NAC-treated cases is associated with cancer stem-like cells. We propose that NAC leads to the selection and/or residue of more aggressive cancer stem-like cells.

Prognostic value and clinicopathological differences of HIFs in colorectal cancer: evidence from meta-analysis

Background

The prognostic value of HIFs in colorectal cancer was evaluated in a large number of studies, but the conclusions were inconclusive. Meanwhile, clinicopathologic differences of HIF-1α and HIF-2α were rarely compared in recent studies.

Methodology

Identical search strategies were used to search relevant literatures in the PubMed and Web of Science databases. The prognostic significances and clinicopathological differences of HIFs in CRC were analyzed.

Principal Findings

A total of 23studies comprising 2984 CRC patients met the inclusion criteria. The results indicated that overexpressed HIFs were significantly associated with increase of mortality risk, including overall survival (OS) (HR 2.06 95%CI 1.55–2.74) and disease free survival (HR 2.84, 95%CI 1.87–4.31). Subgroup analysis revealed that both overexpressed HIF-1α and HIF-2α had correlations with worse prognosis. The pooled HRs were 2.01 (95% CI: 1.55–2.6) and 2.07(95% CI: 1.01–4.26). Further subgroup analysis on HIF-1α was performed by study location, number of patients, quality score and cut-off value. The results showed that HIF-1α overexpression was significantly associated with poor OS, particularly in Asian countries (HR 2.3, 95% CI: 1.74–3.01), while not in European or other countries. In addition, overexpression of HIF-1α was closely related with these clinicopathological features, including Dukes' stages (OR 0.39, 95% CI: 0.17–0.89), UICC stages (OR 0.42 95% CI: 0.3–0.59), depth of invasion (OR 0.71, 95% CI: 0.51–0.99), lymphnode status (OR 0.49, 95% CI: 0.32–0.73) and metastasis (OR 0.29, 95% CI: 0.11–0.81). While overexpression of HIF-2α was only associated with grade of differentiation (OR 0.48, 95% CI: 0.29–0.81).

Conclusions

This study showed that both HIF-1α and HIF-2α overexpression were associated with an unfavorable prognosis. HIF-1α overexpression seemed to be associated with worse prognosis in Asian countries. Additionally, HIF-1α and HIF-2α indicated distinct clinicopathologic features.

CD133: A cancer stem cells marker, is used in colorectal cancers

Colorectal cancer is one of the most common malignant tumors worldwide. A model of cancer development involving cancer stem cells has been put forward because it provides a possible explanation of tumor hierarchy. Cancer stem cells are characterized by their proliferation, tumorigenesis, differentiation, and self-renewal capacities, and chemoradiotherapy resistance. Due to the role of cancer stem cells in tumor initiation and treatment failure, studies of cancer stem cell markers, such as CD133, have been of great interest. CD133, a five-transmembrane glycoprotein, is widely used as a marker to identify and isolate colorectal cancer stem cells. This marker has been investigated to better understand the characteristics and functions of cancer stem cells. Moreover, it can also be used to predict tumor progression, patient survival, chemoradiotherapy resistance and other clinical parameters. In this review, we discuss the use of CD133 in the identification of colorectal cancer stem cell, which is currently controversial. Although the function of CD133 is as yet unclear, we have discussed several possible functions and associated mechanisms that may partially explain the role of CD133 in colorectal cancers. In addition, we focus on the prognostic value of CD133 in colorectal cancers. Finally, we predict that CD133 may be used as a possible target for colorectal cancer treatment.

Prognostic value of changes in the expression of stem cell markers in the peripheral blood of patients with colon cancer

Cancer stem cells play an important role in carcinogenesis and resistance to treatment and may lead to metastasis. The isolation of circulating stem cells involves cell sorting based on the presence of cell surface markers. Many surface markers such as CD133, c-Kit, SOX, OCT4 and TWIST have been reported. In the present study, we determined the expression of different stem cell markers and their variation in expression at different stages of the treatment process. Samples of EDTA blood were collected from metastatic colorectal cancer patients, and circulating cancer stem cells were isolated for the analysis of the expression of stem cell markers using RT-PCR. These findings were correlated with the response to therapy. All statistical analyses were performed using the GraphPad Prism 5.03 software. Significant differences were found in the expression levels of the markers CD133, SOX2, OCT4 and TWIST1. No differences were found in c-Kit expression. Correlation in the expression levels of most of the markers was observed. Expression of CD133, OCT4, SOX2 and TWIST1 had a predictive value for colon cancer behavior. Evaluation of this stem cell gene expression panel may be useful for predicting the response during the process of treatment, and the relative easy access to samples facilitates this method. Moreover the correlation between CD133 and TWIST1 expression may be associated with tumor regrowth and metastatic relapse.

CD133 expression and the prognosis of colorectal cancer: a systematic review and meta-analysis

Objective

CD133 has recently been reported as a marker of cancer stem-like cells in colorectal cancer (CRC). However, its predictive value in CRC still remains controversial. In this study, we aimed to evaluate the association between the expression of CD133 and clinicopathological features and the outcome of CRC patients by performing a meta-analysis.

Methods

A comprehensive literature search for relevant studies published up to December 2012 was performed using PubMed, MEDLINE and ISI Web of Science. Only articles in which CD133 antigen was detected in situ localisation by immunohistochemical staining were included. This meta-analysis was done using RevMan 4.2 software.

Results

We found that a total of 15 studies involving 810 CD133-high and 1487 CD133-low patients met the inclusion criteria for the analysis of 5-year overall survival (OS) rate. In a random-effects model, the results showed that CD133-high expression in colorectal cancer was an independent prognostic marker correlating with both OS rate (RR = 0.67, 95%CI 0.54–0.82, P<0.01) and disease free survival (DFS) rate (RR = 0.71, 95%CI 0.52–0.96, P = 0.03). CD133-high expression was also associated with more T3,4 tumor invasion, N positive and vascular invasion cases, corresponding to a risk difference of 1.12 (95%CI 1.01–1.23, P = 0.03), 1.31 (95%CI 1.06–1.63, P = 0.01) and 1.24 (95%CI 1.08–1.41, P<0.01), respectively. However, when types of histology, lymphatic invasion and distant metastasis were considered, CD133 overexpression was not significantly related with these clinicopathological parameters.

Conclusion

Our meta-analysis results suggest that CD133 is an efficient prognostic factor in CRC. Higher CD133 expression is significantly associated with poorer clinical outcome and some clinicopathological factors such as T category, N category and vascular invasion in CRC patients.

Hypoxia-inducing factors as master regulators of stemness properties and altered metabolism of cancer- and metastasis-initiating cells

Accumulating lines of experimental evidence have revealed that hypoxia-inducible factors, HIF-1α and HIF-2α, are key regulators of the adaptation of cancer- and metastasis-initiating cells and their differentiated progenies to oxygen and nutrient deprivation during cancer progression under normoxic and hypoxic conditions. Particularly, the sustained stimulation of epidermal growth factor receptor (EGFR), insulin-like growth factor-1 receptor (IGF-1R), stem cell factor (SCF) receptor KIT, transforming growth factor-β receptors (TGF-βRs) and Notch and their downstream signalling elements such as phosphatidylinositol 3′-kinase (PI3K)/Akt/molecular target of rapamycin (mTOR) may lead to an enhanced activity of HIFs. Moreover, the up-regulation of HIFs in cancer cells may also occur in the hypoxic intratumoral regions formed within primary and secondary neoplasms as well as in leukaemic cells and metastatic prostate and breast cancer cells homing in the hypoxic endosteal niche of bone marrow. The activated HIFs may induce the expression of numerous gene products such as induced pluripotency-associated transcription factors (Oct-3/4, Nanog and Sox-2), glycolysis- and epithelial-mesenchymal transition (EMT) programme-associated molecules, including CXC chemokine receptor 4 (CXCR4), snail and twist, microRNAs and angiogenic factors such as vascular endothelial growth factor (VEGF). These gene products in turn can play critical roles for high self-renewal ability, survival, altered energy metabolism, invasion and metastases of cancer cells, angiogenic switch and treatment resistance. Consequently, the targeting of HIF signalling network and altered metabolic pathways represents new promising strategies to eradicate the total mass of cancer cells and improve the efficacy of current therapies against aggressive and metastatic cancers and prevent disease relapse.

Single nucleotide polymorphisms in the HIF-1α gene and chemoradiotherapy of locally advanced rectal cancer

The aim of this study was to investigate the predictive impact of polymorphisms in the HIF-1α gene on the response to chemoradiotherapy (CRT) in rectal cancer. This study included two cohorts of patients with locally advanced rectal cancer receiving long-course CRT. The HIF-1α C1772T (rs11549465), G1790A (rs11549467) and c(*)191T>C (rs2057482) polymorphisms were investigated in the test cohort (n=65), and HIF-1α c(*)191T>C was analysed in the validation cohort (n=198). No correlations were identified between the polymorphisms and clinicopathological factors. The HIF-1α C1772T and HIF-1α G1790A polymorphisms demonstrated no correlation with tumour response to CRT in the test cohort. The HIF-1α c(*)191T>C CC genotype was marginally associated with a higher rate of complete tumour response (P=0.05) in the test cohort, while the HIF-1α c(*)191T>C CC genotype was associated with a poor tumour response (P=0.03) in the validation cohort. In conclusion, these results suggest that HIF-1α polymorphisms have no value as predictors of response to neoadjuvant CRT in rectal cancer. The results of the HIF-1α c(*)191T>C in two cohorts differ and emphasise the importance of biomarker validation.

Rapid re-expression of CD133 protein in colorectal cancer cell lines in vitro and in vivo

Studies related to the cancer stem cell hypothesis are challenging because of the imperfect tools to identify cell populations of interest and controversy on the usefulness of established cancer cell lines. We previously found CD133 to not be selective for a tumor-propagating or radioresistant population in a near-diploid, microsatellite-instable colorectal carcinoma (CRC) cell line. Because of discrepant literature data, we herein systematically analyzed the behavior of microsatellite-stable cell line subpopulations reflecting the more frequent carcinogenesis pathway in spontaneous CRC. CD133⁺ and CD133(-/low) populations were isolated by fluorescence-activated cell sorting and further processed. HT29 and SW620 cells were studied in detail in monolayer and/or spheroid culture assays and upon subcutaneous injection in NMRI (nu/nu) mice using a limiting dilution approach. CD133(-/low) HT29 cells showed a significantly lower clonogenic survival and reduced spheroid formation capacity than their CD133⁺ counterparts. However, the cell populations neither differed in growth kinetics and response to treatment in vitro nor in tumor formation capacity when injecting as low as 10 cells. CD133(-/low) HT29 cells rapidly re-expressed CD133 protein in vitro and in vivo as shown by flow cytometry and/or western blot analyses, and they also showed a particular survival benefit under tissue normoxic conditions. In contrast, CD133 protein in the CD133⁺ population was quite stable throughout culturing. The observation of CD133 re-expression and lack of difference in tumor take rate of subpopulations was confirmed in SW620 cells. Here, we found cell density to affect CD133 re-expression in the CD133(-)-sorted population. And even SW480 cells, classified as a CD133⁻ cell line, presented some CD133 protein on their surface upon in vivo engraftment. We conclude that (i) CD133 protein expression shows high plasticity in CRC cell lines, and (ii) in vitro CD133 status on the cell surface neither determines tumorigenic potential nor CD133 profile in vivo.

Hypoxia-related proteins in patients with rectal cancer undergoing neoadjuvant combined modality therapy

BACKGROUND

We have previously demonstrated the prognostic significance of rectal cancer pathologic response to neoadjuvant chemoradiation. Recent studies in other cancers have reported that hypoxia influences response to neoadjuvant chemoradiation.

OBJECTIVE

This study aimed to 1) characterize hypoxia-related protein expression in locally advanced rectal cancer before neoadjuvant chemoradiation, 2) determine the comodulation of hypoxia-related protein expression, and 3) evaluate the relationship between hypoxia-related protein expression and overall survival, time to recurrence, and tumor regression grade.

DESIGN

Immunohistochemical analysis of 4 hypoxia-related proteins (HIF-1α, CA-IX, VEGF, and GLUT-1) was performed on archival pretreatment rectal cancer biopsies.

PATIENTS

: Eighty-five patients with locally advanced rectal cancer treated with neoadjuvant radiation and 5-fluorouracil-based chemotherapy were included.

MAIN OUTCOME MEASURES

The impact of hypoxia-related protein expression on outcome was evaluated by use of Cox proportional hazards model. Hypoxia-related protein expression was correlated with tumor regression grade by use of Spearman correlation coefficients.

RESULTS

Median follow-up was 54 months. CA-IX expression was associated with overall survival (p = 0.01). HIF-1α expression was weakly correlated with VEGF (r = 0.26, p = 0.02) and GLUT-1 (r = 0.35, p = 0.001). Hypoxia-related protein expression was not associated with time to recurrence or Mandard tumor regression grade.

CONCLUSIONS

Elevated CA-IX expression may be associated with poorer overall survival in locally advanced rectal cancer treated by neoadjuvant chemoradiation and resection. The expression of the hypoxia-related proteins HIF-1α, VEGF, and GLUT-1 may be comodulated in locally advanced rectal cancer. Further studies are needed to evaluate the mechanisms governing hypoxia regulation and the role of hypoxia in rectal cancer response to neoadjuvant chemoradiation.

Angiogenesis-related agents in esophageal cancer

INTRODUCTION

Esophageal cancer is an aggressive disease with poor prognosis. The majority of the patients are diagnosed at an advanced stage and many with early stage disease will develop recurrent disease.

AREAS COVERED

Angiogenesis is essential to the progress and aggressiveness of solid malignancies. Success of anti-angiogenic therapy in colorectal, lung and breast cancers is a proof of principle. Thus far, evidence for benefit from anti-angiogenic therapy in esophageal cancer is lacking. Several Phase II trials with different agents have provided mixed results and the only Phase III trial in the esophageal and gastric cancer failed to show that these agents improve overall survival (OS). However, lack of observed benefit could be due to the challenges specific to the management of esophageal cancers as well as issues with the design of clinical trials for anti-angiogenic therapy.

EXPERT OPINION

An understanding of the biology of the esophageal cancer and its management is essential to the development of anti-angiogenic therapy in this disease. This article reviews the management of esophageal cancer and elaborates on the challenges in the development of anti-angiogenic therapy in esophageal cancer. At the end, strategies are proposed for successful development of anti-angiogenic therapy in esophageal cancer.

Enrichment of CD133-expressing cells in rectal cancers treated with preoperative radiochemotherapy is an independent marker for metastasis and survival

BACKGROUND

The transmembrane glycoprotein CD133 (cluster of differentiation 133; also known as Prominin or PROM1) has been described as a potential stem cell marker in colorectal cancer and is associated with higher tumorigenic potential and resistance to radiochemotherapy (RCT). In this study, CD133 expression was evaluated in pre-RCT tumor biopsies and the corresponding post-RCT surgical specimens from patients with locally advanced rectal adenocarcinoma, and expression levels were correlated with histopathologic features and clinical follow-up.

METHODS

One hundred twenty-six patients with International Union Against Cancer (UICC) stage II/III rectal cancer who received preoperative 5-fluorouracil (5-FU)-based RCT within the German Rectal Cancer Trials were investigated. Pre-RCT and post-RCT CD133 expression levels were determined using immunohistochemistry and were correlated with histopathologic parameters, tumor regression grade, cancer recurrence, and patient survival.

RESULTS

Compared with pre-RCT biopsies, significantly higher CD133 expression was observed in tumor specimens (P = .01). However, no correlations were observed for either biopsies or tumor specimens between CD133 expression levels, histopathologic characteristics, or survival. In matched analyses of corresponding biopsy/tumor pairs, patients who had an increased fraction of CD133-expressing (CD133+) cells after preoperative RCT had significantly higher residual tumor stages (P = .02) and lower histopathologic tumor regression (P < .01). Moreover, these patients had significantly reduced disease-free survival and cancer-specific overall survival in univariate analysis (P < .001 and P = .004, respectively) and multivariate analysis (P = .003 and P = .024, respectively).

CONCLUSIONS

The enrichment of CD133+ cancer cells during preoperative RCT was correlated with minor local tumor response, increased distant cancer recurrence, and decreased survival. The current results indicate that the up-regulation of intratumoral CD133 expression, in contrast to absolute pre-RCT and post-RCT CD133 levels, plays an important role in tumor progression and metastasis in patients with rectal cancer who are receiving neoadjuvant RCT.

Colorectal Cancer Stem Cells: Biology and Therapeutic Implications

The hypothesis that cancer is driven by a subpopulation of tumor-initiating or cancer stem cells (CSC), defined by their selective ability for extensive self-renewal and capacity to give rise to nontumorigenic cancer cell progeny through differentiation, has been validated experimentally in diverse human malignancies. Translational relevance of the CSC hypothesis is underlined by emerging novel strategies designed to target all subpopulations within a given tumor in order to effect cancer eradication and improve patient outcomes. Colorectal cancer stem cells (CRSCs) have been identified and successfully isolated by several research groups based on distinct cell-surface marker characteristics. Identification of CRSC populations has led to a wave of discoveries describing novel self-renewal and drug resistance mechanisms in colorectal cancer that represent novel future therapeutic targets. In this review, we will discuss emerging CRSC-specific pathways and the therapeutic promise of targeting this cancer population in colorectal cancer patients.