Chemoresistance of CD133(+) colon cancer may be related with increased survivin expression

Mitochondria in Cancer Stem Cells: From an Innocent Bystander to a Central Player in Therapy Resistance

Cancer continues to rank among the world's leading causes of mortality despite advancements in treatment. Cancer stem cells, which can self-renew, are present in low abundance and contribute significantly to tumor recurrence, tumorigenicity, and drug resistance to various therapies. The drug resistance observed in cancer stem cells is attributed to several factors, such as cellular quiescence, dormancy, elevated aldehyde dehydrogenase activity, apoptosis evasion mechanisms, high expression of drug efflux pumps, protective vascular niche, enhanced DNA damage response, scavenging of reactive oxygen species, hypoxic stability, and stemness-related signaling pathways. Multiple studies have shown that mitochondria play a pivotal role in conferring drug resistance to cancer stem cells, through mitochondrial biogenesis, metabolism, and dynamics. A better understanding of how mitochondria contribute to tumorigenesis, heterogeneity, and drug resistance could lead to the development of innovative cancer treatments.

Destroying the Shield of Cancer Stem Cells: Natural Compounds as Promising Players in Cancer Therapy

In a scenario where eco-sustainability and a reduction in chemotherapeutic drug waste are certainly a prerogative to safeguard the biosphere, the use of natural products (NPs) represents an alternative therapeutic approach to counteract cancer diseases. The presence of a heterogeneous cancer stem cell (CSC) population within a tumor bulk is related to disease recurrence and therapy resistance. For this reason, CSC targeting presents a promising strategy for hampering cancer recurrence. Increasing evidence shows that NPs can inhibit crucial signaling pathways involved in the maintenance of CSC stemness and sensitize CSCs to standard chemotherapeutic treatments. Moreover, their limited toxicity and low costs for large-scale production could accelerate the use of NPs in clinical settings. In this review, we will summarize the most relevant studies regarding the effects of NPs derived from major natural sources, e.g., food, botanical, and marine species, on CSCs, elucidating their use in pre-clinical and clinical studies.

Drug and apoptosis resistance in cancer stem cells: a puzzle with many pieces

Resistance to anticancer agents and apoptosis results in cancer relapse and is associated with cancer mortality. Substantial data have provided convincing evidence establishing that human cancers emerge from cancer stem cells (CSCs), which display self-renewal and are resistant to anticancer drugs, radiation, and apoptosis, and express enhanced epithelial to mesenchymal progression. CSCs represent a heterogeneous tumor cell population and lack specific cellular targets, which makes it a great challenge to target and eradicate them. Similarly, their close relationship with the tumor microenvironment creates greater complexity in developing novel treatment strategies targeting CSCs. Several mechanisms participate in the drug and apoptosis resistance phenotype in CSCs in various cancers. These include enhanced expression of ATP-binding cassette membrane transporters, activation of various cytoprotective and survival signaling pathways, dysregulation of stemness signaling pathways, aberrant DNA repair mechanisms, increased quiescence, autophagy, increased immune evasion, deficiency of mitochondrial-mediated apoptosis, upregulation of anti-apoptotic proteins including c-FLIP [cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein], Bcl-2 family members, inhibitors of apoptosis proteins, and PI3K/AKT signaling. Studying such mechanisms not only provides mechanistic insights into these cells that are unresponsive to drugs, but may lead to the development of targeted and effective therapeutics to eradicate CSCs. Several studies have identified promising strategies to target CSCs. These emerging strategies may help target CSC-associated drug resistance and metastasis in clinical settings. This article will review the CSCs drug and apoptosis resistance mechanisms and how to target CSCs.

Impact of Cancer Stem Cells on Therapy Resistance in Gastric Cancer

Gastric cancer (GC) is the fourth leading cause of cancer death worldwide, with an average 5-year survival rate of 32%, being of 6% for patients presenting distant metastasis. Despite the advances made in the treatment of GC, chemoresistance phenomena arise and promote recurrence, dissemination and dismal prognosis. In this context, gastric cancer stem cells (gCSCs), a small subset of cancer cells that exhibit unique characteristics, are decisive in therapy failure. gCSCs develop different protective mechanisms, such as the maintenance in a quiescent state as well as enhanced detoxification procedures and drug efflux activity, that make them insusceptible to current treatments. This, together with their self-renewal capacity and differentiation ability, represents major obstacles for the eradication of this disease. Different gCSC regulators have been described and used to isolate and characterize these cell populations. However, at the moment, no therapeutic strategy has achieved the effective targeting of gCSCs. This review will focus on the properties of cancer stem cells in the context of therapy resistance and will summarize current knowledge regarding the impact of the gCSC regulators that have been associated with GC chemoradioresistance.

The Great Escape: The Power of Cancer Stem Cells to Evade Programmed Cell Death

Cancer is one of the primary causes of death worldwide. Tumour malignancy is related to tumor heterogeneity, which has been suggested to be due to a small subpopulation of tumor cells named cancer stem cells (CSCs). CSCs exert a key role in metastasis development, tumor recurrence, and also epithelial-mesenchymal transition, apoptotic resistance, self-renewal, tumorigenesis, differentiation, and drug resistance. Several current therapies fail to eradicate tumors due to the ability of CSCs to escape different programmed cell deaths. Thus, developing CSC-selective and programmed death-inducing therapeutic approaches appears to be of primary importance. In this review, we discuss the main programmed cell death occurring in cancer and the promising CSC-targeting agents developed in recent years. Even if the reported studies are encouraging, further investigations are necessary to establish a combination of agents able to eradicate CSCs or inhibit their growth and proliferation.

SNP rs2240688 in CD133 gene on susceptibility and clinicopathological features of hepatocellular carcinoma

Background

CD133 is one of the important cancer stem cells (CSCs) markers of hepatocellular carcinoma (HCC). The aim of this study was to explore the relationship between CD133 single-nucleotide polymorphisms (SNPs) and risk factors associated with HCC susceptibility and clinicopathological features in HCC cases and healthy controls from the Guangxi region of southern China.

Methods

A case control study was conducted, including 565 HCC patients and 561 control subjects. The genotyping of rs2240688 was performed using the SNaPshot method. Unconditional logistic regression was used to correct for gender, age, and other confounding factors. Odds ratio (OR) and its 95% confidence interval (CI) were calculated to analyze the relationship between allele and genotype frequency and the risk of HCC.

Results

The distribution frequencies of CD133 alleles and genotypes in the HCC case group and the control group were statistically significant (P<0.05). The CA heterozygous (P=0.003, OR =1.463, 95% CI: 1.134–1.887) and CC homozygous genotypes (P=0.036, OR =1.910, 95% CI: 1.044–3.493), as well as C carrier status (P=0.004, OR =1.465, 95% CI: 1.136–1.889) and C alleles (P=0.004, OR =1.465, 95% CI: 1.136–1.889), were associated with an increased risk of HCC. Additionally, in the subgroup analysis of CD133 rs2240688 polymorphism and clinical characteristics, the results showed that the genotype distribution of CD133 rs2240688 was significantly different in genotype distribution of metastasis and alanine aminotransferase (ALT).

Conclusions

the expression of miRNA binding site rs2240688 of tumor stem cell marker gene CD133 in HCC may be a promising marker for the prediction of HCC, but larger studies are still needed.

Cellular Mechanisms Accounting for the Refractoriness of Colorectal Carcinoma to Pharmacological Treatment

Simple Summary

Colorectal cancer (CRC) causes a high number (more than 800,000) of deaths worldwide each year. Better methods for early diagnosis and the development of strategies to enhance the efficacy of the therapeutic approaches used to complement or substitute surgical removal of the tumor are urgently needed. Currently available pharmacological armamentarium provides very moderate benefits to patients due to the high resistance of tumor cells to respond to anticancer drugs. The present review summarizes and classifies into seven groups the cellular and molecular mechanisms of chemoresistance (MOC) accounting for the failure of CRC response to the pharmacological treatment.

Abstract

The unsatisfactory response of colorectal cancer (CRC) to pharmacological treatment contributes to the substantial global health burden caused by this disease. Over the last few decades, CRC has become the cause of more than 800,000 deaths per year. The reason is a combination of two factors: (i) the late cancer detection, which is being partially solved by the implementation of mass screening of adults over age 50, permitting earlier diagnosis and treatment; (ii) the inadequate response of advanced unresectable tumors (i.e., stages III and IV) to pharmacological therapy. The latter is due to the existence of complex mechanisms of chemoresistance (MOCs) that interact and synergize with each other, rendering CRC cells strongly refractory to the available pharmacological regimens based on conventional chemotherapy, such as pyrimidine analogs (5-fluorouracil, capecitabine, trifluridine, and tipiracil), oxaliplatin, and irinotecan, as well as drugs targeted toward tyrosine kinase receptors (regorafenib, aflibercept, bevacizumab, cetuximab, panitumumab, and ramucirumab), and, more recently, immune checkpoint inhibitors (nivolumab, ipilimumab, and pembrolizumab). In the present review, we have inventoried the genes involved in the lack of CRC response to pharmacological treatment, classifying them into seven groups (from MOC-1 to MOC-7) according to functional criteria to identify cancer cell weaknesses. This classification will be useful to pave the way for developing sensitizing tools consisting of (i) new agents to be co-administered with the active drug; (ii) pharmacological approaches, such as drug encapsulation (e.g., into labeled liposomes or exosomes); (iii) gene therapy interventions aimed at restoring the impaired function of some proteins (e.g., uptake transporters and tumor suppressors) or abolishing that of others (such as export pumps and oncogenes).

The Multiple Roles of the IAP Super-family in cancer

The Inhibitor of Apoptosis proteins (IAPs) are a family of proteins that are mainly known for their anti-apoptotic activity and ability to directly bind and inhibit caspases. Recent research has however revealed that they have extensive roles in governing numerous other cellular processes. IAPs are known to modulate ubiquitin (Ub)-dependent signaling pathways through their E3 ligase activity and influence activation of nuclear factor κB (NF-κB). In this review, we discuss the involvement of IAPs in individual hallmarks of cancer and the current status of therapies targeting these critical proteins.

Stem Cell Markers Predict the Response to Sorafenib in Patients with Hepatocellular Carcinoma

Background/Aims

Sorafenib remains the only approved molecular targeted agent for hepatocellular carcinoma (HCC); however, reliable biomarkers that predict its efficacy are still lacking. The aim of this study was to explore whether cancer stem cell (CSC) markers have a predictive role with regard to the sorafenib response in HCC patients.

Methods

We enrolled 47 patients with HCC for whom tumor samples obtained before starting sorafenib treatment were available. RNA was extracted from formalin-fixed, paraffin-embedded samples, and real-time polymerase chain reaction was used to quantify mRNA expression of the CSC genes EpCAM, CD13, CK8, CD24, CD44, CD90, CD133, SALL4, ALDH1A1, ALB, and AFP.

Results

Of 47 patients, 14.9% and 74.5% had vascular invasion and extrahepatic spread, respectively. Patients with low CD133 expression tended to have longer progression-free survival (PFS) than those with high CD133 expression (5.5 months vs 4.0 months), although without statistical significance. The expression levels of other markers were not associated with PFS. When examining markers in combination, patients with high CD133 and CD90 expression had shorter PFS rates than those with low expression (2.7 months vs 5.5 months; p=0.04). Patients with low CD133 and EpCAM expression demonstrated better PFS than those with high expression (7.0 months vs 4.2 months; p=0.04). Multivariable analysis indicated that an Eastern Cooperative Oncology Group performance status score of 1 and high CD133/CD90 expression were significantly associated with shorter PFS.

Conclusions

Overexpression of the CSC markers CD133 and CD90 in HCC was associated with poorer response to sorafenib. These two genes may serve as predictive biomarkers for sorafenib therapy.

CRISPR-Cas9 mediated CD133 knockout inhibits colon cancer invasion through reduced epithelial-mesenchymal transition

We previously reported that CD133, as a putative cancer stem cell marker, plays an important role in cell proliferation and invasion in colon cancer. To understand the role of CD133 expression in colon cancer, we evaluated the inhibitory effect of CD133 in colon cancer cells. In this study, we generated CD133^knockout colon cancer cells (LoVo) using the CRISPR-Cas9 gene editing system. CD133⁺ colon cancer cells (LoVo) were infected with the lentiviral vector carrying CD133 gRNA and purified cell by culturing single cell colonies. CD133^knockout cells was validated by western blot and flow cytometry analysis. In functional study, we observed a significant reduction in cell proliferation and colony formation in CRISPR-Cas9 mediated CD133 ^knockout cells in compare with control (P < 0.001). We also found the anticancer effect of stattic was dependent on CD133 expression in colon cancer cells. Although CD133^knockout cells could not completely block the tumorigenic property, they showed remarkable inhibitory effects on the ability of cell migration and invasion (P < 0.001). In addition, we examined the epithelial mesenchymal transition (EMT)-related protein expression by western blot. The result clearly showed a loss of vimentin expression in CD133^knockout cells. Therefore, CRISPR-Cas9 mediated CD133^knockout can be an effective treatment modality for CD133⁺ colon cancer through reducing the characteristics of cancer stem cells.

Regulatory mechanisms of microRNAs in colorectal cancer and colorectal cancer stem cells

Colorectal cancer (CRC) is one of the most lethal and hard-to-treat cancers in the world, which in its advanced stages, surgery and chemotherapy are the main common treatment approaches. The microRNAs (miRNAs), as novel markers for CRC detection, promote their regulatory effects via the 3'-untranslated binding region (3'-UTR) of target messenger RNA in posttranscriptional regulation of genes and also play a pivotal role in modulating resistance to chemotherapeutic agents. These small noncoding RNAs have also a critical role in CRC stem cells (CRCSCs) regulation, comprising self-renewal, differentiation, and tumorigenesis. Cancer stem cells (CSCs) are distinctive cell types inside a tumor tissue that are believed to derive from normal somatic stem cells. The CSCs have self-renewal abilities, angiogenesis, as well as specific surface markers expression characteristics. Furthermore, they are frequently criticized for tumor maintenance, treatment resistance, tumor development, and distant metastasis. In this review, we discuss the current understandings of CRCSCs and their environment with a focus on the role of miRNAs on the regulation of CSCs and their targeting application in CRC treatment.

Regulation of Osteosclerosis by Inoculated Cd133+ PC3 Cells in Bone-marrow Microenvironmental Niches

Bone is the most common site of prostate cancer (PC) metastasis. Studies suggest that cancer stem cells (CSCs) are associated with stemness characteristics, providing some support for the concept that CSCs act as osteosclerotic precursors in bone microenvironmental niches. Here, we asked whether ectopic overexpression of CD133 maintains stability of CSCs in human PC cell lines and induces the changes of molecular features in the bone microenvironment. Ectopic overexpression of CD133 in PC3 or DU145 cells led to increased expression of ALDHA1, OCT4, and NANOG, enhanced colony‐forming ability, and increased ALDH activity. In addition, micro‐CT imaging, confocal microscopy, and H&E staining of mouse tissue confirmed that CD133 overexpression in PC3 and DU145 led to marked osteolytic bone tumor. However, expression of osteoblastic markers such as collagen type I, bone sialoprotein, and osteocalcin (OC) at the tumor margin of CD133‐overexpressing PC3 tumors in mouse tibiae was higher than that of CD133‐overexpressing DU145 tumors with osteosclerotic molecular features. In addition, expression of osteopontin (OPN) mRNA/protein by CD133‐overexpressing PC3 cells was higher than that by DU145 cells. Especially, conditioned medium (CM) from PC3^CD133+ cells increased osterix (OSX) activity in bone marrow stromal cells (BMSCs), resulting in increased expression of OC mRNA/protein resulted in increased staining of mineralized matrix by Alizarin red. However, CM from OPN silenced PC3^CD133+ cells led to a reduction of OC mRNA and protein expression through OSX activity resulted in reduced amount of mineralized matrix. In conclusion, these findings suggest that CD133 plays a functional role in regulating CSC characteristics in PCs and modulates their abilities in which induce the osteosclerosis of BMSCs. In addition, OPN from CSCs acts as a niche component that promotes osteosclerosis by supporting osteoblastic differentiation of BMSCs. © 2019 The Authors JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Correlation study of GAPDH, Bcl-2, and Bax protein immunoexpression in patients with colorectal adenocarcinoma

Introduction

Colorectal cancer (CRC) is the third and second most commonly diagnosed cancer worldwide in males and females, respectively. Despite prominent progress in diagnosis and treatment, the recurrence rates are still high. A tumour hypoxic environment leads to an increase in glycolytic metabolism. The crucial intermediate component of glycolysis, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), could play a significant role in cancer progression. An increased level of GAPDH has been described in oncogene-induced transformation and anti-apoptotic function. In other studies, GAPDH has been involved in apoptosis induction.

Aim

We examined colorectal adenocarcinoma samples to assess the immunoexpression of GAPDH protein. We also evaluated the correlation between the expression of GAPDH protein and apoptotic parameters including expression of Bcl2 and Bax.

Material and methods

Paraffin sections were incubated for 60 min with primary antibody against GAPDH, Bcl-2, and Bax.

Results

Results of our study have shown that GAPDH expression in colorectal cancer is upregulated. We revealed significant positive correlation between expression of this protein and grade and size of tumour, and regional lymph node involvement. In the case of apoptosis-associated proteins, e.g. Bcl-2 and Bax, we found negative correlations between expression of these proteins and grade and size of tumour, lymphovascular invasion, and regional lymph node involvement. Finally, we demonstrated that GAPDH up-regulation is connected with down-regulation in Bcl-2 and Bax.

Conclusions

Up-regulation of GAPDH protein and down-regulation of Bcl-2 and Bax may result in increased of cancer.

Nature-inspired development of unnatural meroterpenoids as the non-toxic anti-colon cancer agents

Structural analogues of anti-cancer natural product, dysideanone, were synthesized starting from Wieland-Miescher ketone derivative. In vitro studies have been conducted to evaluate the anti-cancer potential of these unnatural meroterpenoids against colon cancer. Synthesized carbotetracycles were found to be more active as compared to their acyclic carbinol-derivatives. Unnatural carbotetracycles 4b-e, 4h, 4i and 12 were found to be highly effective against the human colon adenocarcinoma cells with IC₅₀ concentrations of 7.5-20 μM. In this series, the carbotetracyclic catechol 4e (IC₅₀ = 7.5 μM) and quinone 12 (IC₅₀ = 8 μM) were found to be the most potent compounds having the IC₅₀ of less than 10 μM with no cytotoxic effect on the normal cells. Downregulation of Cox-2 and survivin and cell cycle arrest eventually leading to apoptosis were found to be the underlying mechanism of the anti-cancer effect of these unnatural meroterpenoids.

ALDH1A3 upregulation and spontaneous metastasis formation is associated with acquired chemoresistance in colorectal cancer cells

Background

Efficiency of colorectal carcinoma treatment by chemotherapy is diminished as the resistance develops over time in patients. The same holds true for 5-fluorouracil, the drug used in first line chemotherapy of colorectal carcinoma.

Methods

Chemoresistant derivative of HT-29 cells was prepared by long-term culturing in increasing concentration of 5-fluorouracil. Cells were characterized by viability assays, flow cytometry, gene expression arrays and kinetic imaging. Immunomagnetic separation was used for isolation of subpopulations positive for cancer stem cells-related surface markers. Aldehyde dehydrogenase expression was attenuated by siRNA. In vivo studies were performed on SCID/bg mice.

Results

The prepared chemoresistant cell line labeled as HT-29/EGFP/FUR is assigned with different morphology, decreased proliferation rate and 135-fold increased IC₅₀ value for 5-fluorouracil in comparison to parental counterparts HT-29/EGFP. The capability of chemoresistant cells to form tumor xenografts, when injected subcutaneously into SCID/bg mice, was strongly compromised, however, they formed distant metastases in mouse lungs spontaneously. Derived cells preserved their resistance in vitro and in vivo even without the 5-fluorouracil selection pressure. More importantly, they were resistant to cisplatin, oxaliplatin and cyclophosphamide exhibiting high cross-resistance along with alterations in expression of cancer-stem cell markers such as CD133, CD166, CD24, CD26, CXCR4, CD271 and CD274. We also detected increased aldehyde dehydrogenase (ALDH) activity associated with overexpression of specific ALDH isoform 1A3. Its inhibition by siRNA approach partially sensitized cells to various agents, thus linking for the first time the ALDH1A3 and chemoresistance in colorectal cancer.

Conclusion

Our study demonstrated that acquired chemoresistance goes along with metastatic and migratory phenotype and can be accompanied with increased activity of aldehyde dehydrogenase. We describe here the valuable model to study molecular link between resistance to chemotherapy and metastatic dissemination.

A review of preoperative chemoradiotherapy for lower rectal cancer

In Western countries, rectal cancer has been treated by chemoradiotherapy (CRT) for several decades now, and good local control has been reported. However, Japanese guidelines did not strongly recommend CRT, because CRT is only useful for achieving local control and imbues no survival benefit. For this reason, CRT was rarely used to treat rectal cancer in Japan. However, in the 2000s, several studies involving CRT began to be reported from Western countries, such as “correlation between pathological complete response and survival,” “induction chemotherapy followed by CRT,” and “watch-and-wait policies.” These studies were directly correlated with survival of and benefits to the patients. Given these findings, Japanese institutions have recently begun to introduce CRT for rectal cancer. Therefore, in the present study, we reviewed several topics regarding CRT for rectal cancer.

Activated STAT3 may participate in tumor progression through increasing CD133/survivin expression in early stage of colon cancer

The activation of signal transducer and activator of transcription 3 (STAT3) by elevated interleukin (IL) levels has been reported to regulate tumorigenesis both in vitro and in vivo. However, the clinical implication of p-STAT3 expression in colon cancer is still controversial. In this study, we evaluated the effect of STAT3 inactivation on biologic behavior of primary (Caco-2) and metastatic colon cancer cells (LoVo and SNU407) and the relation of p-STAT3 expression with the invasion of colon tumor. In vitro study, the STAT3 inhibition by siRNA and stattic treatment significantly reduced colony formation and cell migration and decreased CD133 and survivin the expression compared with a control in all three cell lines. Furthermore, primary cancer cells exhibited a marked decrease in CD133 expression and increased apoptosis compared to metastatic cells after stattic treatment. The immunohistochemical assay using clinical samples of colonic tumors with various invasion depth showed that p-STAT3 expression was inversely associated with tumor invasion (p = 0.001, hazard ratio (HR) = 0.328, 95% confidence interval (95%CI): 0.170-0.632). In conclusion, p-STAT3 may participate in the progression of the early stage of colon cancer through the up-regulation of CD133, which in turn induces survivin expression. However, the regulatory mechanism of these molecules in tumor progression in vivo is need to be more verified.

Resistance to Cell Death and Its Modulation in Cancer Stem Cells

Accumulating evidence has demonstrated that human cancers arise from various tissues of origin that initiate from cancer stem cells (CSCs) or cancer-initiating cells. The extrinsic and intrinsic apoptotic pathways are dysregulated in CSCs, and these cells play crucial roles in tumor initiation, progression, cell death resistance, chemo- and radiotherapy resistance, and tumor recurrence. Understanding CSC-specific signaling proteins and pathways is necessary to identify specific therapeutic targets that may lead to the development of more efficient therapies selectively targeting CSCs. Several signaling pathways-including the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR), maternal embryonic leucine zipper kinase (MELK), NOTCH1, and Wnt/Β-catenin&and expression of the CSC markers CD133, CD24, CD44, Oct4, Sox2, Nanog, and ALDH1A1 maintain CSC properties. Studying such pathways may help to understand CSC biology and lead to the development of potential therapeutic interventions to render CSCs more sensitive to cell death triggered by chemotherapy and radiation therapy. Moreover, recent demonstrations of dedifferentiation of differentiated cancer cells into CSC-like cells have created significant complexity in the CSCs hypothesis. Therefore, any successful therapeutic agent or combination of drugs for cancer therapy must eliminate not only CSCs but differentiated cancer cells and the entire bulk of tumor cells. This review article expands on the CSC hypothesis and paradigm with respect to major signaling pathways and effectors that regulate CSC apoptosis resistance. Moreover, selective CSC apoptotic modulators and their therapeutic potential for making tumors more responsive to therapy are discussed. The use of novel therapies, including small-molecule inhibitors of specific proteins in signaling pathways that regulate stemness, proliferation and migration of CSCs, immunotherapy, and noncoding microRNAs may provide better means of treating CSCs.

The molecular mechanisms of chemoresistance in cancers

Overcoming intrinsic and acquired drug resistance is a major challenge in treating cancer patients because chemoresistance causes recurrence, cancer dissemination and death. This review summarizes numerous molecular aspects of multi-resistance, including transporter pumps, oncogenes (EGFR, PI3K/Akt, Erk and NF-κB), tumor suppressor gene (p53), mitochondrial alteration, DNA repair, autophagy, epithelial-mesenchymal transition (EMT), cancer stemness, and exosome. The chemoresistance-related proteins are localized to extracellular ligand, membrane receptor, cytosolic signal messenger, and nuclear transcription factors for various events, including proliferation, apoptosis, EMT, autophagy and exosome. Their cross-talk frequently appears, such as the regulatory effects of EGFR-Akt-NF-κB signal pathway on the transcription of Bcl-2, Bcl-xL and survivin or EMT-related stemness. It is essential for the realization of the target, individualized and combine therapy to clarify these molecular mechanisms, explore the therapy target, screen chemosensitive population, and determine the efficacy of chemoreagents by cell culture and orthotopic model.

Overcoming chemoresistance in cancer stem cells with the help of microRNAs in colorectal cancer

It has been recognized that acute resistance to chemotherapy mediated by post-transcriptional and translational control is crucial to influence response and survival in cancer treatment. Tumor cells are highly heterogeneous and have the ability to adapt a resistance phenotype through epigenetic regulations such as microRNAs. This poses a major challenge to the treatment of advanced stage colon cancer patients. Colon cancer stem cells have been identified as one of the major contributors to resistance of colon cancer to chemotherapy. Through various mechanisms, these cells are able to resist the effects of traditional chemotherapeutics. The challenge posed by these cells is further enhanced by their plastic nature, where cells can transition between non-stem cancer cells and cancer stem cells creating a moving target. In this editorial, we discuss some of the recent advancements in overcoming chemoresistance associated with colon cancer stem cells with the help of microRNAs.

Expression of the cancer stem cell markers ABCG2 and OCT-4 in right-sided colon cancer predicts recurrence and poor outcomes

Right-sided colon cancer (RCC) has a poorer prognosis and a higher relapse rate than left-sided colon cancer (LCC). Like cancer stem cells (CSCs), RCC cells cannot be fully eradicated and are often involved in relapse or metastasis. Because CSCs may be linked with poor outcomes, CSC markers may have prognostic value in RCC. ATP-binding cassette sub-family G member 2 (ABCG2) and OCT-4 (also known as POU5F1) are among the most useful markers for CSC identification. We therefore examined the malignant behavior of ABCG2 and OCT-4 in vitro and in vivo, and their expression was assessed in pathology tissues obtained from clinicopathologically recurrent and non-recurrent cases. Our survey suggested associations between ABCG2 and OCT-4 expression and RCC clinicopathological variables. No correlations were detected between ABCG2 or OCT-4 expression and age, gender, tumor size, or tumor shape, but ABCG2 expression correlated with TNM stage, tumor differentiation, and lymphovascular invasion. Additionally, expression of both ABCG2 and OCT-4 correlated with RCC recurrence and poor outcomes.

Influence of microRNAs and Long Non-Coding RNAs in Cancer Chemoresistance

Innate and acquired chemoresistance exhibited by most tumours exposed to conventional chemotherapeutic agents account for the majority of relapse cases in cancer patients. Such chemoresistance phenotypes are of a multi-factorial nature from multiple key molecular players. The discovery of the RNA interference pathway in 1998 and the widespread gene regulatory influences exerted by microRNAs (miRNAs) and other non-coding RNAs have certainly expanded the level of intricacy present for the development of any single physiological phenotype, including cancer chemoresistance. This review article focuses on the latest research efforts in identifying and validating specific key molecular players from the two main families of non-coding RNAs, namely miRNAs and long non-coding RNAs (lncRNAs), having direct or indirect influences in the development of cancer drug resistance properties and how such knowledge can be utilised for novel theranostics in oncology.

Gambogic acid potentiates the chemosensitivity of colorectal cancer cells to 5-fluorouracil by inhibiting proliferation and inducing apoptosis

Chemotherapy using 5-fluorouracil (5-FU) for colorectal cancer (CRC) has low specificity and response rates, leading to severe side effects. Gambogic acid (GA), a traditional Chinese medicine, has multi-targeted anticancer effects, including growth inhibition and apoptosis induction. However, it is unclear whether a combination of 5-FU and GA has synergistic anticancer effects in CRC cells. In this study, SW480 and HCT116 human CRC cells and human intestinal epithelial cells (IECs) were treated with different concentrations of 5-FU, GA or 5-FU+GA. A Cell Counting kit-8 assay was conducted to quantify cell proliferation. The combination index (CI) was calculated and the median-effect principle was applied to analyze the interaction between 5-FU and GA. Flow cytometry was used to determine the percentage of cells undergoing apoptosis. Reverse transcription-quantitative polymerase chain reaction and western blotting were applied to measure P53, survivin and thymidylate synthase (TS) mRNA and protein levels. It was found that 5-FU+GA more pronouncedly inhibited cell growth and induced apoptosis, compared with either monotherapy. CI values <1 indicated the synergistic effects of the drugs. 5-FU+GA further decreased P53, survivin and TS mRNA and protein levels in the two CRC cell lines compared with single drugs, whereas increased P53 protein levels were observed in HCT116 cells. Moreover, 5-FU+GA did not increase cytotoxicity to IECs. These results demonstrate that GA enhances the anticancer effects of 5-FU on CRC cells. Combined treatment with 5-FU and GA is effective and safe for CRC cells, and may become a promising chemotherapy treatment.

Clinicopathologic Significance of Survivin Expression in Relation to CD133 Expression in Surgically Resected Stage II or III Colorectal Cancer

Background

Cancer stem cells have been investigated as new targets for colorectal cancer (CRC) treatment. We recently reported that CD133⁺ colon cancer cells showed chemoresistance to 5-fluorouracil through increased survivin expression and proposed the survivin inhibitor YM155 as an effective therapy for colon cancer in an in vitro study. Here, we investigate the relationship between survivin and CD133 expression in surgically resected CRC to identify whether the results obtained in our in vitro study are applicable to clinical samples.

Methods

We performed immunohistochemical staining for survivin and CD133 in surgically resected tissue from 187 stage II or III CRC patients. We also comparatively analyzed apoptosis according to survivin and CD133 expression using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling.

Results

The results of the Mantel-Haenszel test established a linear association between nuclear survivin and CD133 expression (p = .018), although neither had prognostic significance, according to immunohistochemical expression level. No correlation was found between survivin expression and the following pathological parameters: invasion depth, lymph node metastasis, or histologic differentiation (p > .05). The mean apoptotic index in survivin⁺ and CD133⁺ tumors was higher than that in negative tumors: 5.116 ± 4.894 in survivin⁺ versus 4.103 ± 3.691 in survivin^– (p = .044); 5.165 ± 4.961 in CD133⁺ versus 4.231 ± 3.812 in CD133^– (p = .034).

Conclusions

As observed in our in vitro study, survivin expression is significantly related to CD133 expression. Survivin may be considered as a new therapeutic target for chemoresistant CRC.

The small molecule survivin inhibitor YM155 may be an effective treatment modality for colon cancer through increasing apoptosis

Survivin has a known beneficial role in the survival of both cancer cells and normal cells. Therapies targeting survivin have been proposed as an alternative treatment modality for various tumors; however, finding the proper indication for this toxic therapy is critical for reducing unavoidable side effects. We recently observed that high survivin expression in CD133(+) cells is related to chemoresistance in Caco-2 colon cancer cells. However, the effect of survivin-targeted therapy on CD133(+) colon cancer is unknown. In this study, we investigated the roles of CD133 and survivin expression in colon cancer biology in vitro and comparatively analyzed the anticancer effects of survivin inhibitor on CD133(+) cells (ctrl-siRNA group) and small interfering RNA (siRNA)-induced CD133(-) cells (CD133-siRNA group) obtained from a single colon cancer cell line. CD133 knockdown via siRNA transfection did not change the tumorigenicity of cells, although in vitro survivin expression levels in CD133(+) cells were higher than those in siRNA-induced CD133(-) cells. The transfection procedure seemed to induce survivin expression. Notably, a significant number of CD133(-) cells (33.8%) was found in the cell colonies of the CD133-siRNA group. In the cell proliferation assay after treatment, YM155 and a combination of YM155 and 5-fluorouracil (5-FU) proved to be far more effective than 5-FU alone. A significantly increased level of apoptosis was observed with increasing doses of YM155 in all groups. However, significant differences in therapeutic effect and apoptosis among the mock, ctrl-siRNA, and CD133-siRNA groups were not detected. Survivin inhibitor is an effective treatment modality for colon cancer; however, the role of CD133 and the use of survivin expression as a biomarker for this targeted therapy must be verified.

Growth inhibition and chemo-radiosensitization of head and neck squamous cell carcinoma (HNSCC) by survivin-siRNA lentivirus

BACKGROUND

Survivin expression is often associated with aggressive tumor behavior and therapy resistance. In this study, we investigated the effect of survivin knockdown by survivin-siRNA lentiviral vector (Svv-Lent) on the response of HNSCC to chemo-radiotherapy, tumor growth and metastasis.

METHODS

Four human HNSCC (OSC19, Cal27, Cal33 and FaDu) and one normal HOK cell lines were included in the study, and survivin knockdown was achieved with Svv-Lent treatment. Cell proliferation and apoptosis were measured by MTT and TUNEL assay, respectively. Transwell assays were performed to measure in vitro cell migration and matrigel invasion. Xenograft tumors were developed in nude mice by injecting Cal27 cells subcutaneously and following tail-vein injection of lung and liver metastasis.

RESULTS

Knockdown of survivin significantly suppressed HNSCC cell proliferation and induced apoptosis in vitro. Survivin inhibition could also significantly reduce in vitro cell migration and matrigel invasion that might be due to inactivation of matrix metalloproteinases. In vivo studies showed significant repression of Cal27 xenograft tumor growth and tissue metastasis leading to improvement in mice survival in the Svv-Lent treated group compared to controls. Our data indicated that survivin expression in HNSCC cells contributed to chemo-radioresistance, and its down-regulation increased anti-cancer effects of paclitaxel, cisplatin and radiation.

CONCLUSIONS

Our findings suggest that sustained survivin expression facilitates HNSCC tumor growth and confers resistance to chemo-radiotherapy. Svv-Lent therapy may be able to enhance the cytotoxic effect of commonly used anticancer drugs such as cisplatin and paclitaxel, and radiotherapy that could provide a promising strategy for the effective control of resistant head and neck cancer.