Expression and functional role of ALDH1 in cervical carcinoma cells

Unveiling diagnostic and therapeutic strategies for cervical cancer: biomarker discovery through proteomics approaches and exploring the role of cervical cancer stem cells

Cervical cancer (CC) is a major global health problem and leading cause of cancer deaths among women worldwide. Early detection through screening programs has reduced mortality; however, screening compliance remains low. Identifying non-invasive biomarkers through proteomics for diagnosis and monitoring response to treatment could improve patient outcomes. Here we review recent proteomics studies which have uncovered biomarkers and potential drug targets for CC. Additionally, we explore into the role of cervical cancer stem cells and their potential implications in driving CC progression and therapy resistance. Although challenges remain, proteomics has the potential to revolutionize the field of cervical cancer research and improve patient outcomes.

ALDEFLUOR activity, ALDH isoforms, and their clinical significance in cancers

High aldehyde dehydrogenase (ALDH) activity is a metabolic feature of adult stem cells and various cancer stem cells (CSCs). The ALDEFLUOR system is currently the most commonly used method for evaluating ALDH enzyme activity in viable cells. This system is applied extensively in the isolation of normal stem cells and CSCs from heterogeneous cell populations. For many years, ALDH1A1 has been considered the most important subtype among the 19 ALDH family members in determining ALDEFLUOR activity. However, in recent years, studies of many types of normal and tumour tissues have demonstrated that other ALDH subtypes can also significantly influence ALDEFLUOR activity. In this article, we briefly review the relationships between various members of the ALDH family and ALDEFLUOR activity. The clinical significance of these ALDH isoforms in different cancers and possible directions for future studies are also summarised.

The Expanding Role of Cancer Stem Cell Marker ALDH1A3 in Cancer and Beyond

Aldehyde dehydrogenase 1A3 (ALDH1A3) is one of 19 ALDH enzymes expressed in humans, and it is critical in the production of hormone receptor ligand retinoic acid (RA). We review the role of ALDH1A3 in normal physiology, its identification as a cancer stem cell marker, and its modes of action in cancer and other diseases. ALDH1A3 is often over-expressed in cancer and promotes tumor growth, metastasis, and chemoresistance by altering gene expression, cell signaling pathways, and glycometabolism. The increased levels of ALDH1A3 in cancer occur due to genetic amplification, epigenetic modifications, post-transcriptional regulation, and post-translational modification. Finally, we review the potential of targeting ALDH1A3, with both general ALDH inhibitors and small molecules specifically designed to inhibit ALDH1A3 activity.

Expression of ALDH1 plays the important role during generation and progression in human cervical cancer

Cervical cancer which is caused by persistent infection with oncogenic human papillomavirus (HPV), is the third most common cancer. HPV infection causes the progression of the normal cervix to cervical intraepithelial neoplasia (CIN) because it often occurs at the function conversion of the cervical squamous epithelium and columnar epithelium zone, further to invasive carcinoma. The difference in the ALDH1 expression was very significant. With the progression of cervical cancer, reports explained obviously increased nuclear and cytoplasm ALDH1 staining in comparisons of cervical carcinomas and normal cervix (P < 0.0001), cervical carcinomas compared with CIN (P = 0.0002). Therefore, ALDH1 as a stem marker, not only resists cervical cancer but also resists in normal cervix and CIN tissues. Developing an experimental method to discover cervical cancer earlier is feasible. Furthermore, the ALDH1 was expressed in human cervical cancer cell lines (Hela, SiHa, CaSki, HT-3, and C33A) together with western blot and immunocytochemical analysis. ALDH1 plays a significant role in nuclear and cytoplasm staining by immunochemistry in single or clustered HT-3 and C33A cells. However, western blot and immunochemical analysis did not detect ALDH1 in HeLa or CaSki, SiHa cells. We also discovered that there were no remarkable differences in age, tumor size, clinical TNM staging, multiple pelvic lymph node metastasis, or histological staging (p > 0.05) between the ALDH1-positive groups in 100 cervical cancer tissues. But after the control variable age, different ALDH rating survival function contrasted, it can be concluded that the higher ALDH1 scores with the survival of patients with the worse condition.

Regulation of the aryl hydrocarbon receptor in cancer and cancer stem cells of gynecological malignancies: An update on signaling pathways

Gynecological malignancies are a female type of cancers that affects the reproductive system. Cancer metastasis or recurrence mediated by cellular invasiveness occurs at advanced stages of cancer progression. Cancer Stem Cells (CSCs) enrichment in tumors leads to chemoresistance, which results in cancer mortality. Exposure to environmental pollutants such as polycyclic aromatic hydrocarbons is associated with an increased the risk of CSC enrichment in gynecological cancers. One of the important pathways that mediates the metabolism and bioactivation of these environmental chemicals is the transcription factor, aryl hydrocarbon receptor (AhR). The present review explores the molecular mechanisms regulating the crosstalk and interaction of the AhR with cancer-related signaling pathways, such as apoptosis, epithelial-mesenchymal transition, immune checkpoints, and G-protein-coupled receptors in several gynecological malignancies such as ovarian, uterine, endometrial, and cervical cancers. The review also discusses the potential of targeting the AhR pathway as a novel chemotherapy for gynecological cancers.

Aldehyde Dehydrogenase Isoform 1 Predicts a Poor Prognosis of Acute Cerebral Infarction

To investigate the prognostic potential of serum aldehyde dehydrogenase isoform 1 (ALDH1) level in acute cerebral infarction, and the molecular mechanism in mediating neurological deficits, a total of 120 acute cerebral infarction cases within 72 h of onset were retrospectively analyzed. Serum ALDH1 level in them was detected by qRT-PCR. Receiver operating characteristic (ROC) and Kaplan–Meier curves were depicted for assessing the diagnostic and prognostic potentials of ALDH1 in acute cerebral infarction, respectively. An in vivo acute cerebral infarction model in rats was established by performing MCAO, followed by evaluation of neurological deficits using mNSS and detection of relative levels of ALDH1, Smad2, Smad4, and p21 in rat brain tissues. Pearson's correlation test was carried out to verify the correlation between ALDH1 and mNSS and relative levels of Smad2, Smad4, and p21. Serum ALDH1 level increased in acute cerebral infarction patients. A high level of ALDH1 predicted a poor prognosis of acute cerebral infarction patients. In addition, ALDH1 was sensitive and specific in distinguishing acute cerebral infarction cases, presenting a certain diagnostic potential. mNSS was remarkably higher in acute cerebral infarction rats than that of controls. Compared with sham operation group, relative levels of ALDH1, Smad2, and Smad4 were higher in brain tissues of modeling rats, whilst p21 level was lower. ALDH1 level in brain tissues of modeling rats was positively correlated to mNSS, and mRNA levels of Smad2 and Smad4, but negatively correlated to p21 level. Serum ALDH1 level is a promising prognostic and diagnostic factor of acute cerebral infarction, which is correlated to 90-day mortality. Increased level of ALDH1 in the brain of cerebral infarction rats is closely linked to neurological function, which is associated with the small mothers against decapentaplegic (Smad) signaling and p21.

Cancer Stem Cells and Their Possible Implications in Cervical Cancer: A Short Review

Cervical cancer (CC) is the fourth most common type of gynecological malignancy affecting females worldwide. Most CC cases are linked to infection with high-risk human papillomaviruses (HPV). There has been a significant decrease in the incidence and death rate of CC due to effective cervical Pap smear screening and administration of vaccines. However, this is not equally available throughout different societies. The prognosis of patients with advanced or recurrent CC is particularly poor, with a one-year relative survival rate of a maximum of 20%. Increasing evidence suggests that cancer stem cells (CSCs) may play an important role in CC tumorigenesis, metastasis, relapse, and chemo/radio-resistance, thus representing potential targets for a better therapeutic outcome. CSCs are a small subpopulation of tumor cells with self-renewing ability, which can differentiate into heterogeneous tumor cell types, thus creating a progeny of cells constituting the bulk of tumors. Since cervical CSCs (CCSC) are difficult to identify, this has led to the search for different markers (e.g., ABCG2, ITGA6 (CD49f), PROM1 (CD133), KRT17 (CK17), MSI1, POU5F1 (OCT4), and SOX2). Promising therapeutic strategies targeting CSC-signaling pathways and the CSC niche are currently under development. Here, we provide an overview of CC and CCSCs, describing the phenotypes of CCSCs and the potential of targeting CCSCs in the management of CC.

miR-326 inhibits the cell proliferation and cancer stem cell-like property of cervical cancer in vitro and oncogenesis in vivo via targeting TCF4

Background

Cervical cancer ranks as one of the most prevalent female malignancies globally, and its treatment with new targets has been the focus of current research. The present study set out to investigate the function of microRNA-326 (miR-326) in vitro and in vivo and to verify the direct targeting of transcription factor 4 (TCF4) by miR-326.

Methods

The detection of messenger RNA (mRNA) expressing miR-326 and TCF4 in cervical cancer cell lines and tumor samples was conducted using quantitative real-time polymerase chain (qRT-PCR). A dual-luciferase reporter assay was carried out to detect the target relationship of miR-326 with TCF4. A Cell Counting Kit-8 (CCK-8) assay was employed to detect the effect of miR-326 on CasKi cell viability. Flow cytometry and western blotting were employed to examine the effects of miR-326 on cancer stem cell (CSC)-like property. Tumor weight was measured in orthotopic xenograft mouse models. Immunohistochemistry was employed to analyze the protein expression levels of Ki-67, proliferating cell nuclear antigen (PCNA), CD44, and SRY-box 4 (SOX4).

Result

Downregulation of the mRNA expression levels of miR-326 was observed in cervical cancer cell lines and tumor tissue, while the levels of TCF4 were upregulated. The dual-luciferase reporter assay revealed binding of miR-326 to the three prime untranslated region (3'-UTR) of TCF4. In vitro assays demonstrated that miR-326 inhibited CasKi cell proliferation through regulating TCF4. miR-326 also suppressed the CSC-like property of CasKi cells by targeting TCF4. Furthermore, the protein expression levels of cyclin D1, β-catenin, and c-Myc were decreased when miR-326 was added to TCF4-transfected cells. In vivo assays demonstrated that miR-326 inhibited tumor weight, growth, and the protein expression levels of Ki-67, PCNA, CD44, SOX4, and β-catenin.

Conclusions

miR-326 acted in a tumor-suppressive manner through its regulation of TCF4, and has potential as a biomarker or therapeutic target for cervical cancer.

Aldehyde Dehydrogenase 1B1 Is Associated with Altered Cell Morphology, Proliferation, Migration and Chemosensitivity in Human Colorectal Adenocarcinoma Cells

Aldehyde dehydrogenases (ALDHs) are NAD(P)⁺-dependent enzymes that catalyze the oxidation of endogenous and exogenous aldehydes to their corresponding carboxylic acids. ALDHs participate in a variety of cellular mechanisms, such as metabolism, cell proliferation and apoptosis, as well as differentiation and stemness. Over the last few years, ALDHs have emerged as cancer stem cell markers in a wide spectrum of solid tumors and hematological malignancies. In this study, the pathophysiological role of ALDH1B1 in human colorectal adenocarcinoma was investigated. Human colon cancer HT29 cells were stably transfected either with human green fluorescent protein (GFP)-tagged ALDH1B1 or with an empty lentiviral expression vector. The overexpression of ALDH1B1 was correlated with altered cell morphology, decreased proliferation rate and reduced clonogenic efficiency. Additionally, ALDH1B1 triggered a G2/M arrest at 24 h post-cell synchronization, probably through p53 and p21 upregulation. Furthermore, ALDH1B1-overexpressing HT29 cells exhibited enhanced resistance against doxorubicin, fluorouracil (5-FU) and etoposide. Finally, ALDH1B1 induced increased migratory potential and displayed epithelial–mesenchymal transition (EMT) through the upregulation of ZEB1 and vimentin and the consequent downregulation of E-cadherin. Taken together, ALDH1B1 confers alterations in the cell morphology, cell cycle progression and gene expression, accompanied by significant changes in the chemosensitivity and migratory potential of HT29 cells, underlying its potential significance in cancer progression.

Insulin growth factor-1 pathway in cervical carcinoma cancer stem cells

Cancer stem cells (CSC) drive tumour progression and are implicated in relapse and resistance to conventional cancer therapies. Identification of differentially expressed genes by gene expression (GEP) profiling may help identify the differentially activated signalling pathways in cancer stem cells as opposed to bulk tumour cells which will provide new insights into cancer stem cell biology and aid in identification of novel therapeutic targets. Our study focused on the inhibition of CSC from cervical cancer cell lines by targeting insulin-like growth factor (IGF), which was identified by differential GEP. Targeted inhibition of IGF-1 by JB-1 trifluoroacetate (inhibitor of IGF) was carried out in SiHa, RSBS-14 and RSBS-43 cervical cancer derived cell lines. Effect of cisplatin was also evaluated. Inhibition of IGF-1 signalling was confirmed by demonstration of reduction in p-Akt levels. The cell biological effects of IGF-1 inhibition included an increase in G2M/S fraction, increased apoptosis and decreased invasive ability. JB-1 and cisplatin showed synergism. However, transcript levels of stemness and EMT markers showed variable levels following IGF inhibition. Overall, this proof-of-concept study has shown that IGF-1 is an attractive target for inhibition of CSC in invasive cervical cancer.

Efficient isolation, culture, purification, and stem cell expression profiles of primary tumor cells derived from uterine cervical squamous cell carcinoma

PROBLEM

Since not too many human uterus cervical squamous cell carcinoma (CSCC) cell lines in existence, efficient isolation, culture, and purification protocols for primary CSCC cells were optimized as a tool for the study of uterus CSCC.

METHOD OF STUDY

The protocols for partial multiple enzymatic digestion and explant cell culture were combined and then the resulting mixed cell component cultures were purified by magnetic-activated cell sorting. Colony-forming assay was utilized for detection of cell carcinogenesis potential, and immunofluorescence was used to detect protein expression of CSCC. Finally, flow cytometry (FCM) was performed to analyze cancer stem cells (CSCs) phenotypic markers as well as programmed cell death ligand 1(PD-L 1).

RESULTS

Freshly isolated cells containing tumor cells and cancer-associated fibroblasts (CAFs) efficiently proliferate to 85% confluence on a 6 cm petri dish in 5-7 days. Anti-epithelial cell adhesion molecule antibody (EpCAM) microbeads were used to successfully separate a homogeneous subpopulation of epithelial tumor cells. Both EpCAM+ and EpCAM- cell subpopulations were able to be passaged more than 30 times. Proportions of tumor cell populations expressed CSCs markers such as CD133, CD24, aldehyde dehydrogenase 1 (ALDH1), and CD44. The vimentin+ & EpCAM- population, defined with CAFs, could express CD146 mesenchymal stem cells marker. Meanwhile, PD-L 1 was identified in most subpopulation of CD44+ cells at low passage numbers.

CONCLUSION

Efficient isolation, culture, and purification protocols for primary CSCC cells were successfully built. Additionally, the profiling of CSCs cell markers might provide promising therapeutic targets and clinic strategies.

Cervical cancer stem cells and other leading factors associated with cervical cancer development

Cervical cancer (CC) is one of the leading causes of cancer-associated mortalities in women from developing countries. Similar to other types of cancer, CC is considered to be a multifactorial disease, involving socioeconomic, cultural, immunological and epigenetic factors, as well as persistent human papilloma virus (HPV) infection. It has been well established that cancer stem cells (CSCs) play an important role in defining tumor size, the speed of development and the level of regression following treatment; therefore, CSCs are associated with a poor prognosis. CSCs have been detected in many types of cancer, including leukemia, pancreatic, colon, esophagus, liver, prostate, breast, gastric and lung cancer. In cervical cancer, CSCs have been associated with resistance to normally used drugs such as cisplatin. The present review summarizes the strategies that high-risk HPV viruses (HPV-16 and HPV-18) have developed to transform normal epithelial cells into cancer cells, as well as the cellular pathways and studies associated with the identification of cervical cancer stem cell biomarkers. In this sense, the present review provides state of the art information regarding CC development.

A Simple, Yet Multifunctional, Nanoformulation for Eradicating Tumors and Preventing Recurrence with Safely Low Administration Dose

Designing simple-structured nanomedicine without lacking key functionalities, thereby avoiding incomplete damage or relapse of tumor with the administration of a safe dose, is pivotal for successful cancer nanotherapy. We herein presented a nanomedicine of photodynamic therapy (PDT) that simply assembled amphiphilic macromolecules of poly-l-lysine conjugating with photosensitizers onto hydrophobic upconverting nanoparticles. We demonstrated that the nanoformulation, despite its simple structure and synthesis, simultaneously possesses multiple features, including substantial payload of photosensitizers, avid cellular internalization both in vitro and in vivo, efficient diffusion and broad distribution in tumor lesion, and potent fatality for cancer stem cells that are refractory to other therapy modalities. Because of the combination of these functionalities, the tumors in mice were eradicated and no relapse was observed after at least 40 days, just with an extremely low intraperitoneal injection dose of 5.6 mg/kg. Our results suggested a strategy for designing multifunctional nanomedicines with simple construct and efficacious therapeutic response and presented the promising potential of PDT for a radical cure of cancer.

Cervical cancer stem cell-associated genes: Prognostic implications in cervical cancer

Cervical cancer is the fourth most common type of gynecological malignancy to affect females, worldwide. Although high-risk human papillomavirus (HR-HPV) infection is the primary etiologic agent associated with the development of cervical cancer, cancer stem cells (CSCs) also serve a prominent role in the development, metastasis, recurrence and prognosis of the disease. CSCs are a small subpopulation of cells that have the ability to self-renew and are present in the majority of tumors, including cervical cancer. Studies describing the phenotype of cervical CSCs (CCSCs) vary in their definition of the expression pattern of principal biomarkers, including Musashi-1, aldehyde dehydrogenase 1, Oct3/4, Sox2 and CD49f. However, these markers are not observed in all cancers, although several may be present in multiple tumor types. The present review describes the potential biomarkers of CSCs in cervical cancer. These CCSC biomarkers may serve as molecular targets to enhance the efficacy and reduce the side effects associated with chemotherapeutic treatment in HR-HPV-positive cervical cancer.

Potential role of cancer stem cells as biomarkers and therapeutic targets in cervical cancer

BACKGROUND

Eradicating cancer stem cells (CSCs) that are termed as the "beating heart" of various malignant tumors, including cervical cancer, holds great importance in cancer therapeutics. CSCs not only confer chemo-radio resistance but also play an important role in tumor metastasis and thereby pose a potential barrier for the cure of cervical cancer. Cervical cancer, a common malignancy among females, is associated with high morbidity and mortality rates, and the study on CSCs residing in the niche is promising.

RECENT FINDINGS

Biomarker approach to screen the cervical CSCs has gained impetus since the past decade. Progress in identification and characterization of the stem cell biomarkers has led to many insights. For the diagnostic purpose, several biomarkers like viral (HPV16), stem cell markers, transcription factors (viz, SOX2, OCT 4, and c-Myc), and CSC surface markers (viz, ALDH1 and CD44) have been identified. The research so far has been directed to study the CSC stemness and demonstrates various gene expression signatures in cervical CSCs. Such studies hold a potential to improve diagnostic accuracy and predict therapeutic response and clinical outcome in patients.

CONCLUSIONS

Stem cell biomarkers have been validated and their therapeutic targets are being developed as "strategies to improve therapeutic ratio in personalized medicine." This review gives a brief overview of the cervical CSC biomarkers, their current and future diagnostic, prognostic, and therapeutic potential.

ALDH as a Stem Cell Marker in Solid Tumors

Aldehyde dehydrogenase (ALDH) is an enzyme that participates in important cellular mechanisms as aldehyde detoxification and retinoic acid synthesis; moreover, ALDH activity is involved in drug resistance, a characteristic of cancer stem cells (CSCs). Even though ALDH is found in stem cells, CSCs and progenitor cells, this enzyme has been successfully used to identify and isolate cell populations with CSC properties from several tumor origins. ALDH is allegedly involved in cell differentiation through its product, retinoic acid. However, direct or indirect ALDH inhibition, using specific inhibitors or retinoic acid, has shown a reduction in ALDH activity, along with the loss of stem cell traits, reduction of cell proliferation, invasion, and drug sensitization. For these reasons, ALDH and retinoic acid are promising therapeutic targets. This review summarizes the current evidence for ALDH as a CSCs marker in solid tumors, as well as current knowledge about the functional roles of ALDH in CSCs. We discuss the controversy of ALDH activity to maintain CSC stemness, or conversely, to promote cell differentiation. Finally, we review the advances in using ALDH inhibitors as anti-cancer drugs.

Cancer stem cell impact on clinical oncology

Cancer is a widespread worldwide chronic disease. In most cases, the high mortality rate from cancer correlates with a lack of clear symptoms, which results in late diagnosis for patients, and consequently, advanced tumor disease with poor probabilities for cure, since many patients will show chemo- and radio-resistance. Several mechanisms have been studied to explain chemo- and radio-resistance to anti-tumor therapies, including cell signaling pathways, anti-apoptotic mechanisms, stemness, metabolism, and cellular phenotypes. Interestingly, the presence of cancer stem cells (CSCs), which are a subset of cells within the tumors, has been related to therapy resistance. In this review, we focus on evaluating the presence of CSCs in different tumors such as breast cancer, gastric cancer, lung cancer, and hematological neoplasias, highlighting studies where CSCs were identified in patient samples. It is evident that there has been a great drive to identify the cell surface phenotypes of CSCs so that they can be used as a tool for anti-tumor therapy treatment design. We also review the potential effect of nanoparticles, drugs, natural compounds, aldehyde dehydrogenase inhibitors, cell signaling inhibitors, and antibodies to treat CSCs from specific tumors. Taken together, we present an overview of the role of CSCs in tumorigenesis and how research is advancing to target these highly tumorigenic cells to improve oncology patient outcomes.

The combination of aldehyde dehydrogenase 1 (ALDH1) and CD44 is associated with poor outcomes in endometrial cancer

Aldehyde dehydrogenase 1 (ALDH1) and CD44 have been established as biomarkers for predicting the survival of many types of cancer patients. This study evaluated the expression and clinical significance of these putative cancer-cell markers in a series of tumor samples from endometrial cancer (EC) patients using tissue microarray. We examined 245 endometrial samples, including 132 (53.87%) pre-malignancy lesions and 113 (46.12%) malignant endometrial lesions from biopsies or hysterectomies. We examined the expression of CD44 and ALDH1 in these samples using immunohistochemistry staining. Correlations in the relative expression of these markers with clinicopathological parameters were also assessed. A high level of expression of ALDH1 was found in 44.25% (50/113) of the endometrial cancer samples, which was significantly correlated with a poor overall survival rate (p = 0.035). High-level CD44 expression was found in 35.4% (40/113) of the cases and was also correlated with a poor overall survival rate (p = 0.035). A simultaneous high expression of both markers was correlated with an extremely poor overall survival (p = 0.013). Our results show that tumors with higher expressions of both ALDH1 and CD44 were related to a poorer overall survival rate among EC patients. The combination of ALDH1 and CD44 could be a promising marker for developing additional targeted therapy for severe endometrial cancers.

Upregulation of stem cell markers ALDH1A1 and OCT4 as potential biomarkers for the early detection of cervical carcinoma

Previous studies have reported the upregulation of stem cell biomarkers that are associated with tumorigenesis, in particular with cancer infiltration, recurrence and metastasis. Infection by human papilloma virus (HPV) is the main etiopathological factor of cervical carcinogenesis, but the expression of stem cell markers in cervical carcinoma and HPV infection have yet to be investigated so far. A total of 94 cases of fresh cervical tissues, 116 cases of paraffin-embedded cervical specimens and 72 cases of peripheral blood samples were collected from Uighur women who were either diagnosed with cervical squamous cell carcinoma (SCC) or cervical intraepithelial neoplasia (CIN) II-III, or from healthy subjects (negative controls, NC). HPV infection was detected in tissue DNA by polymerase chain reaction (PCR) with a HPV genotyping kit. The mRNA expression levels of aldehyde dehydrogenase 1 family member A1 (ALDH1A1), nanog homeobox (NANOG), POU class 5 homeobox 1 (OCT4), SRY-box 2 (SOX2) and twist family BHLH transcription factor 1 (Twist1) were determined using reverse transcription-quantitative PCR (RT-qPCR). Histological analysis was performed in order to examine the protein expression of ALDH1A1 and OCT4 in paraffin-embedded tissue specimens by immunohistochemical staining and the plasma levels of those two proteins was measured by ELISA. RT-qPCR analysis indicated a significant increase in the mRNA expression of ALDH1A1 and OCT4 in CIN II-III and SCC tissue specimens compared with NC (P<0.05). Although the expression levels of NANOG, SOX2 and Twist1 were significantly higher in SCC compared with NC (P<0.05), no significant difference was revealed in CIN II-III tissues compared with SCC or NC (P>0.05). Subsequent analysis by immunohistochemistry staining confirmed that the upregulation of ALDH1A1 and OCT4 was also significantly increased in SCC and CIN II-III compared with controls at the protein level. Notably, ELISA analysis detected significantly higher levels of ALDH1A1 and OCT4 in the peripheral blood (plasma) of patients with SCC compared with healthy subjects. The upregulation of stem cell markers ALDH1A1 and OCT4 in cervical carcinoma and its precursor lesions, in particular in the peripheral blood, indicates that ALDH1A1 and OCT4 may serve as biomarkers for the early detection of cervical carcinoma or for the monitoring of treatment of patients.

Cancer initiating-cells are enriched in the CA9 positive fraction of primary cervix cancer xenografts

Numerous studies have suggested that Cancer Initiating Cells (CIC) can be identified/enriched in cell populations obtained from solid tumors based on the expression of cell surface marker proteins. We used early passage primary cervix cancer xenografts to sort cells based on the expression of the intrinsic hypoxia marker Carbonic Anhydrase 9 (CA9) and tested their cancer initiation potential by limiting dilution assay. We demonstrated that CICs are significantly enriched in the CA9⁺ fraction in 5/6 models studied. Analyses of the expression of the stem cell markers Oct4, Notch1, Sca-1 & Bmi1 showed a trend toward an increase in the CA9⁺ populations, albeit not significant. We present evidence that enhanced autophagy does not play a role in the enhanced growth of the CA9⁺ cells. Our study suggests a direct in vivo functional link between hypoxic cells and CICs in primary cervix cancer xenografts.

Cancer stem cells (CSCs), cervical CSCs and targeted therapies

Accumulating evidence has shown that cancer stem cells (CSCs) have a tumour-initiating capacity and play crucial roles in tumour metastasis, relapse and chemo/radio-resistance. As tumour propagation initiators, CSCs are considered to be promising targets for obtaining a better therapeutic outcome. Cervical carcinoma is the most common gynaecological malignancy and has a high cancer mortality rate among females. As a result, the investigation of cervical cancer stem cells (CCSCs) is of great value. However, the numbers of cancer cells and corresponding CSCs in malignancy are dynamically balanced, and CSCs may reside in the CSC niche, about which little is known to date. Therefore, due to their complicated molecular phenotypes and biological behaviours, it remains challenging to obtain “purified” CSCs and continuously culture CSCs for further in vitro studies without the cells losing their stem properties. At present, CSC-related markers and functional assays are used to purify, identify and therapeutically target CSCs both in vitro and in vivo. Nevertheless, CSC-related markers are not universal to all tumour types, although some markers may be valid in multiple tumour types. Additionally, functional identifications based on CSC-specific properties are usually limited in in vivo studies. Furthermore, an optimal method for identifying potential CCSCs in CCSC studies has not been previously published, and these techniques are currently of great importance. This article updates our knowledge on CSCs and CCSCs, reviews potential stem cell markers and functional assays for identifying CCSCs, and describes the potential of targeting CCSCs in the treatment of cervical carcinoma.

TGF-β1-induced CK17 enhances cancer stem cell-like properties rather than EMT in promoting cervical cancer metastasis via the ERK1/2-MZF1 signaling pathway

Tumor metastasis remains a major obstacle for improving overall cancer survival in cervical cancer (CC), which may be due to the existence of tumor microenvironment-related cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT). The mechanism underlying these processes needs to be further elucidated. Here, we report that TGF-β1, one of the key microenvironmental stimuli, can enhance CSC characteristics, facilitate the EMT, and induce CK17. Silencing CK17 expression attenuated CSC-like properties without affecting the EMT markers induced by TGF-β1, whereas forced overexpression of CK17 promoted lymphatic metastasis in vivo even without EMT inducement. Inhibitors of ERK1/2 signaling drastically decreased the induction of CK17 mediated by TGF-β1. By combined computational and experimental approaches, we identified and validated that MZF1 was a key transcription factor binding to the promoter of CK17. Taken together, these results demonstrate that CK17 induced by the TGF-β1-ERK1/2-MZF1 signaling pathway facilitates metastasis by promoting the acquisition of CSC properties rather than by inducing the EMT process in CC, suggesting that this CK17-related signaling pathway might be a suitable target for the development of therapy for CC metastasis.

Cervical cancer stem cells manifest radioresistance: Association with upregulated AP-1 activity

Transcription factor AP-1 plays a central role in HPV-mediated cervical carcinogenesis. AP-1 has also been implicated in chemo-radio-resistance but the mechanism(s) remained unexplored. In the present study, cervical cancer stem-like cells (CaCxSLCs) isolated and enriched from cervical cancer cell lines SiHa and C33a demonstrated an elevated AP-1 DNA-binding activity in comparison to non-stem cervical cancer cells. Upon UV-irradiation, CaCxSLCs showed a UV exposure duration-dependent higher proliferation and highly increased AP-1 activity whereas it was completely abolished in non-stem cancer cells. CaCxSLCs also showed differential overexpression of c-Fos and c-Jun at transcript as well as in protein level. The loss of AP-1 activity and expression was accompanied by decrease in cell viability and proliferation in UV-irradiated non-stem cancer cells. Interestingly, CaCxSLCs treated with curcumin prior to UV-irradiation abolished AP-1 activity and a concomitant reduction in SP cells leading to abrogation of sphere forming ability, loss of proliferation, induction of apoptosis and the cells were poorly tumorigenic. The curcumin pre-treatment abolished the expression of c-Fos and c-Jun but upregulated Fra-1 expression in UV-irradiated CaCxSLCs. Thus, the study suggests a critical role of AP-1 protein in the manifestation of radioresistance but targeting with curcumin helps in radiosensitizing CaCxSLCs through upregulation of Fra-1.

Clinicopathological Significance of CD133 and ALDH1 Cancer Stem Cell Marker Expression in Invasive Ductal Breast Carcinoma

BACKGROUND

Biomarkers in breast neoplasms provide invaluable information regarding prognosis and help determining the optimal treatment. We investigated the possible correlation between cancer stem cell (CSC) markers (CD133, and ALDH1) in invasive ductal breast carcinomas with some clinicopathological parameters.

AIM

To assess the correlation between expression of cancer stem cell (CSC) markers (CD133, and ALDH1) and clinicopathological parameters of invasive ductal breast carcinomas.

MATERIALS AND METHODS

Immunohistochemical analysis of CD133 and ALDH1 was performed on a series of 120 modified radical mastectomy (MRM) specimens diagnosed as invasive ductal breast carcinoma.

RESULTS

Expression of both CD133 and ALDH1 was significantly changed and related to tumor size, tumor stage (TNM), and lymph node metastasis. A negative correlation between CD133 and ALDH1 was found.

CONCLUSIONS

Detecting the expression of CD133 and ALDH1 in invasive ductal breast carcinomas may be of help in more accurately predicting the aggressive properties and determining the optimal treatment.

Inhibition of TRPM7 by carvacrol suppresses glioblastoma cell proliferation, migration and invasion

Glioblastomas are progressive brain tumors with devastating proliferative and invasive characteristics. Ion channels are the second largest target class for drug development. In this study, we investigated the effects of the TRPM7 inhibitor carvacrol on the viability, resistance to apoptosis, migration, and invasiveness of the human U87 glioblastoma cell line.

The expression levels of TRPM7 mRNA and protein in U87 cells were detected by RT-PCR, western blotting and immunofluorescence. TRPM7 currents were recorded using whole-cell patch-clamp techniques. An MTT assay was used to assess cell viability and proliferation. Wound healing and transwell experiments were used to evaluate cell migration and invasion. Protein levels of p-Akt/t-Akt, p-ERK1/2/t-ERK1/2, cleaved caspase-3, MMP-2 and phosphorylated cofilin were also detected.

TRPM7 mRNA and protein expression in U87 cells is higher than in normal human astrocytes. Whole-cell patch-clamp recording showed that carvacrol blocks recombinant TRPM7 current in HEK293 cells and endogenous TRPM7-like current in U87 cells. Carvacrol treatment reduced the viability, migration and invasion of U87 cells. Carvacrol also decreased MMP-2 protein expression and promoted the phosphorylation of cofilin. Furthermore, carvacrol inhibited the Ras/MEK/MAPK and PI3K/Akt signaling pathways.

Therefore, carvacrol may have therapeutic potential for the treatment of glioblastomas through its inhibition of TRPM7 channels.

Cervical cancer stem cells

The concept of cancer stem cells (CSC) has been established over the past decade or so, and their role in carcinogenic processes has been confirmed. In this review, we focus on cervical CSCs, including (1) their purported origin, (2) markers used for cervical CSC identification, (3) alterations to signalling pathways in cervical cancer and (4) the cancer stem cell niche. Although cervical CSCs have not yet been definitively identified and characterized, future studies pursuing them as therapeutic targets may provide novel insights for treatment of cervical cancer.

Aldehyde Dehydrogenase 1 Expression Predicts Chemoresistance and Poor Clinical Outcomes in Patients with Locally Advanced Cervical Cancer Treated with Neoadjuvant Chemotherapy Prior to Radical Hysterectomy

BACKGROUND

Neoadjuvant chemotherapy (NAC) is an important treatment strategy for cervical cancer; however, few predictive markers of the response to NAC exist. Aldehyde dehydrogenase 1 (ALDH1), a cancer stem cell marker, is associated with chemoresistance in a variety of cancers. This study attempted to investigate the value of ALDH1 as a predictive marker of chemosensitivity and its prognostic value in cervical cancer patients treated with NAC.

METHODS

Immunohistochemistry was used to evaluate ALDH1 expression in matched pre- and post-NAC tumor samples from 52 patients with cervical cancer. Kaplan-Meier analysis and a Cox proportional hazards regression model were applied to determine overall survival (OS) and disease-free survival (DFS).

RESULTS

Fourteen patients (26.9 %) had ALDH1-positive tumors pre-NAC, and ALDH1 expression pre-NAC was significantly associated with a low clinical chemotherapy response rate and clinical non-response. Twenty-two patients (42.3 %) had ALDH1-positive tumors post-NAC, and ALDH1 expression post-NAC was associated with poor DFS and OS (both p = 0.004). Multivariate analysis revealed that ALDH1 expression post-NAC was an independent prognostic factor for OS (hazard ratio 3.513; p = 0.033). Moreover, we observed that ALDH1 expression was increased after NAC in 18 patients (36.7 %). Increased levels of ALDH1 expression after NAC predicted poor DFS and OS (p = 0.013 and p = 0.08, respectively).

CONCLUSIONS

Our findings suggest that ALDH1 expression pre-NAC may be a predictive marker for response to NAC, and ALDH1 expression post-NAC could be a prognostic marker for cervical cancer.

Cervical cancer stem cells: opportunities and challenges

INTRODUCTION

Cervical cancer remains a leading cause of cancer-related deaths in women in spite of screening and vaccination programs. The current treatment strategies including chemotherapy and surgery could only prolong the patient's survival rather than provide a permanent cure. In case of advanced cervical cancer, radical surgery remains the only option which not only affects the child-bearing ability of the patient, but also comes with a continual risk of recurrence of the disease. Hence, there is a need to develop innovative therapeutics. The cancer stem cell hypothesis states that a tumor has a hierarchical cellular structure in which only a small subpopulation, referred to as cancer stem cells (CSCs), is capable of tumorigenesis. The CSCs possess the stem-like properties of self-renewal and can differentiate into non-stem tumor cells.

RESULTS

A large number of studies suggest that CSCs are resistant to the conventional therapies used for cancer treatment. These therapies rather enrich the proportion of CSCs in the tumor by eliminating non-stem tumor cells, thereby causing enhanced drug resistance resulting in relapse of the disease. This makes CSCs as the most likely targets for therapeutic intervention. Also, the increase in the proportion of CSCs in patient samples is associated with poor survival rate, thus highlighting their potential role as prognostic biomarker.

CONCLUSION

The CSCs have been identified and characterized in cervical cancer cell lines, but there are hardly any reports of CSCs in cervical cancer patient samples. This review highlights the current status of research on cervical CSCs, their clinical significance and the challenges in the field.

High aldehyde dehydrogenase activity identifies cancer stem cells in human cervical cancer

High aldehyde dehydrogenase (ALDH) activity characterizes a subpopulation of cells with cancer stem cell (CSC) properties in several malignancies. To clarify whether ALDH can be used as a marker of cervical cancer stem cells (CCSCs), ALDH^high and ALDH^low cells were sorted from 4 cervical cancer cell lines and 5 primary tumor xenografts and examined for CSC characteristics. Here, we demonstrate that cervical cancer cells with high ALDH activity fulfill the functional criteria for CSCs: (1) ALDH^high cells, unlike ALDH^low cells, are highly tumorigenic in vivo; (2) ALDH^high cells can give rise to both ALDH^high and ALDH^low cells in vitro and in vivo, thereby establishing a cellular hierarchy; and (3) ALDH^high cells have enhanced self-renewal and differentiation potentials. Additionally, ALDH^high cervical cancer cells are more resistant to cisplatin treatment than ALDH^low cells. Finally, expression of the stem cell self-renewal-associated transcription factors OCT4, NANOG, KLF4 and BMI1 is elevated in ALDH^high cervical cancer cells. Taken together, our data indicated that high ALDH activity may represent both a functional marker for CCSCs and a target for novel cervical cancer therapies.

TRPM7 channels regulate glioma stem cell through STAT3 and Notch signaling pathways

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor in adults with median survival time of 14.6 months. A small fraction of cancer stem cells (CSC) initiate and maintain tumors thus driving glioma tumorigenesis and being responsible for resistance to classical chemo- and radio-therapies. It is desirable to identify signaling pathways related to CSC to develop novel therapies to selectively target them. Transient receptor potential cation channel, subfamily M, member 7, also known as TRPM7 is a ubiquitous, Ca(2+) and Mg(2+) permeable ion channels that are special in being both an ion channel and a serine/threonine kinase. In studies of glioma cells silenced for TRPM7, we demonstrated that Notch (Notch1, JAG1, Hey2, and Survivin) and STAT3 pathways are down regulated in glioma cells grown in monolayer. Furthermore, phospho-STAT3, Notch target genes and CSC markers (ALDH1 and CD133) were significantly higher in spheroid glioma CSCs when compared with monolayer cultures. The results further show that tyrosine-phosphorylated STAT3 binds and activates the ALDH1 promoters in glioma cells. We found that TRMP7-induced upregulation of ALDH1 expression is associated with increases in ALDH1 activity and is detectable in stem-like cells when expanded as spheroid CSCs. Finally, TRPM7 promotes proliferation, migration and invasion of glioma cells. These demonstrate that TRPM7 activates JAK2/STAT3 and/or Notch signaling pathways and leads to increased cell proliferation and migration. These findings for the first time demonstrates that TRPM7 (1) activates a previously unrecognized STAT3→ALDH1 pathway, and (2) promotes the induction of ALDH1 activity in glioma cells.

Six1 promotes epithelial-mesenchymal transition and malignant conversion in human papillomavirus type 16-immortalized human keratinocytes

Six1, a member of the Six family of homeodomain transcription factors, is overexpressed in various human cancers, and SIX1 overexpression is associated with tumor progression and metastasis. Six1 messenger RNA levels increase during in vitro progression of human papillomavirus type 16 (HPV16)-immortalized human keratinocytes (HKc/HPV16) toward a differentiation-resistant (HKc/DR) phenotype. In this study, we show that HKc/DR-overexpressing Six1 exhibited a more mesenchymal phenotype, as characterized by a fibroblastic appearance and increased invasion. We utilized Whole Human Genome Microarrays to explore the gene expression changes associated with Six1 overexpression in HKc/DR. We found that overexpression of Six1 downregulated epithelial-related genes and upregulated mesenchymal-related genes, which suggests that Six1 overexpression induces epithelial-mesenchymal transition (EMT). Pathway analysis of the microarray data showed alterations in the transforming growth factor-beta (TGF-β) pathway, including enhanced expression of the TGF-β receptor type II (TβRII), and activation of the mitogen-activated protein kinase (MAPK) pathway in HKc/DR-overexpressing Six1, suggesting that Smad-independent pathways of TGF-β signaling may be involved in Six1-mediated EMT. p38 MAPK activation was required for sustained Six1-induced EMT and TβRII overexpression. Finally, we determined that Six1 overexpression in HKc/DR resulted in malignant conversion and increased the cancer stem cell (CSC)-like population. Thus, Six1 overexpression promotes EMT, CSCs properties and malignant conversion in HKc/DR through MAPK activation, which supports the possible use of p38-TβRII inhibitors for the treatment of cancers overexpressing Six1.

Prenatal diagnosis of neuroblastoma by sonography

Background

Zoledronic acid is the most potent osteoclast inhibitor and is widely used for advanced cancer patients with bone metastasis, but its role on cancer stem cells (CSCs) remains unclear. In the present study, we aimed to identify the stemness phenotypic characteristics of CSCs derived from cervical cancer cells and explore the anti-cancer efficiency of zoledronic acid on these cells, as well as the possible molecular mechanisms.

Methods

Stemness phenotypic identification of cervical cancer cells derived CSCs was performed via sphere formation efficiency (SFE), tumorigenesis, immunofluorescence staining, Transwell assay, and western blot. Anti-cancer efficiency of zoledronic acid on these cells (including proliferation, stemness phenotype, apoptosis, and cell cycle) was carried out through MTT assay, SFE, transwell, DAPI staining, flow cytometry, immunofluorescence, TUNEL staining, and western blot, both in vitro and in vivo.

Results

Enhanced self-renewal ability, including SFE and tumorigenesis, was verified in cervical cancer cells derived CSCs compared to parental cervical cancer cells. Specifically, the expression of ALDH1, Sox2, CD49f, Nanog, and Oct4 was significantly up-regulated in cervical cancer cells derived CSCs. Furthermore, enhanced migratory ability was observed in these cells along with up-regulated N-cadherin and Vimentin and down-regulated E-cadherin. Zoledronic acid inhibited cervical cancer cells derived CSCs proliferation in vitro and in vivo. The stemness phenotype of these CSCs including tumor sphere formation, migration, as well as the expression of the aforementioned associated markers was also suppressed. In addition, zoledronic acid significantly induced apoptosis and cell cycle arrest of cervical cancer cells derived CSCs in a dose-dependent manner. Mechanistically, the expression of phosphorylated Erk1/2 and Akt was significantly increased in cervical cancer cells derived CSCs compared to parental cervical cancer cells. Zoledronic acid inhibited phosphorylated Erk1/2 and Akt in cervical cancer cells derived CSCs. IGF-1, a potent stimulator for Erk1/2 and PI3K/Akt, attenuated the aforementioned anti-cancer effect of zoledronic acid.

Conclusions

Zoledronic acid inhibited the growth of cervical cancer cells derived CSCs through attenuating their stemness phenotype, inducing apoptosis, and arresting cell cycle. The suppression of phosphorylated Erk1/2 and Akt was involved in this process.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1109-z) contains supplementary material, which is available to authorized users.

The effect of several intertrial intervals on the 1 Hz interference effect

Gynecologic cancers cause over 600,000 deaths annually in women worldwide. The development of chemoresistance after initial rounds of chemotherapy contributes to tumor relapse and death due to gynecologic malignancies. In this regard, cancer stem cells (CSCs), a subpopulation of stem cells with the ability to undergo self-renewal and clonal evolution, play a key role in tumor progression and drug resistance. Aldehyde dehydrogenases (ALDH) are a group of enzymes shown to be robust CSC markers in gynecologic and other malignancies. These enzymes also play functional roles in CSCs, including detoxification of aldehydes, scavenging of reactive oxygen species (ROS), and retinoic acid (RA) signaling, making ALDH an attractive therapeutic target in various clinical scenarios. In this review, we discuss the critical roles of the ALDH in driving stemness in different gynecologic malignancies. We review inhibitors of ALDH, both general and isoform-specific, which have been used to target CSCs in gynecologic cancers. Many of these inhibitors have been shown to be effective in preclinical models of gynecologic malignancies, supporting further development in the clinic. Furthermore, ALDH inhibitors, including 673A and CM037, synergize with chemotherapy to reduce tumor growth. Thus, ALDH-targeted therapies hold promise for improving patient outcomes in gynecologic malignancies.