Peripherical Blood hsa-miR-335-5p Quantification as a Prognostic, but Not Diagnostic, Marker of Gastric Cancer.

Gastric cancer (GC) is a leading cause of death, and this pathology often receives a diagnosis in an advanced stage. The development of a less invasive and cost-effective test for detection is essential for decreasing the mortality rate and increasing the life expectancy of GC patients. We evaluated the potential targeting of CD54/ICAM1, a marker of gastric cancer stem cells, with miRNAs to detect GC in blood samples. The analyses included 79 blood samples, 38 from GC patients and 41 from healthy donors, who attended INCan, México City. The total RNA was obtained from the blood plasma, and RT-PCR and qPCR were performed to obtain the relative expression of each miRNA. Hsa-miR-335-5p was detected in the plasma of GC patients and healthy donors at the same levels. The ROC curve analyses indicated that this miRNA was not a candidate for the molecular diagnosis of GC. We did not observe a correlation between the expression of hsa-miR-335-5p and clinical variables; however, the Kaplan-Meier analyses indicated that, in patients who survived more than 12 months, a lower expression of hsa-miR-335-5p was correlated with a better prognosis. It would be convenient to evaluate a larger panel of miRNAs, including miRNAs expressed in a limited number of cell types or with a low number targets, to obtain more specific candidates for developing a robust test for the diagnosis/prognosis of GC.

Circulating Gastric Cancer Stem Cells as Blood Screening and Prognosis Factor in Gastric Cancer.

Gastric cancer (GC) is the fourth leading cause of cancer-related death, associated with late diagnosis and treatment resistance. Currently, screening tests for GC are not cost-effective or have low accuracy. Previously, we described an extended phenotype of gastric cancer stem cells (GCSCs; CD24+CD44+CD54+EpCAM+) that is associated with metastasis and tumor stage in GC patients. The goal of the current research is to evaluate the presence of these GCSCs in the peripheral blood of GC patients and healthy volunteers. A total of 73 blood samples were collected from 32 GC patients and 41 healthy volunteers. After peripheral blood mononuclear cell (PBMC) extraction, multiparametric flow cytometry was performed looking for GCSCs. Using clustering data through artificial intelligence (AI), we defined high/low levels of circulating GCSCs (cGCSCs) and proceeded to evaluate its association with clinical and prognostic variables. Finally, a diagnostic test analysis was performed evaluating patients and healthy volunteers. We found that cGCSCs are present in most GC patients with a mean concentration of 0.48%. The AI clustering showed two groups with different cGCSC levels and clinical characteristics. Through statistical analysis, we confirmed the association between cGCSC levels and lymph node metastasis, distant metastasis, and overall survival. The diagnostic test analysis showed sensibility, specificity, and area under the curve (AUC) of 83%, 95%, and 0.911, respectively. Our results suggest that the assessment of cGCSCs CD24+CD44+CD54+EpCAM+ could be a potential noninvasive test, with prognostic value, as well as highly sensitive and specific for screening or diagnosis of GC; however, a larger scale study will be necessary to confirm this.

Metformin induces ZFP36 by mTORC1 inhibition in cervical cancer-derived cell lines.

BACKGROUND: Metformin, a widely prescribed antidiabetic drug, has shown several promising effects for cancer treatment. These effects have been shown to be mediated by dual modulation of the AMPK-mTORC1 axis, where AMPK acts upstream of mTORC1 to decrease its activity. Nevertheless, alternative pathways have been recently discovered suggesting that metformin can act through of different targets regulation. METHODS: We performed a transcriptome screening analysis using HeLa xenograft tumors generated in NOD-SCID mice treated with or without metformin to examine genes regulated by metformin. Western Blot analysis, Immunohistochemical staining, and RT-qPCR were used to confirm alterations in gene expression. The TNMplot and GEPIA2 platform were used for in silico analysis of genes found up-regulated by metformin, in cervical cancer patients. We performed an AMPK knock-down using AMPK-targeted siRNAs and mTOR inhibition with rapamycin to investigate the molecular mechanisms underlying the effect of metformin in cervical cancer cell lines. RESULTS: We shown that metformin decreases tumor growth and increased the expression of a group of antitumoral genes involved in DNA-binding transcription activator activity, hormonal response, and Dcp1-Dcp2 mRNA-decapping complex. We demonstrated that ZFP36 could act as a new molecular target increased by metformin. mTORC1 inhibition using rapamycin induces ZFP36 expression, which could suggest that metformin increases ZFP36 expression and requires mTORC1 inhibition for such effect. Surprisingly, in HeLa cells AMPK inhibition did not affect ZFP36 expression, suggesting that additional signal transducers related to suppressing mTORC1 activity, could be involved. CONCLUSIONS: These results highlight the importance of ZFP36 activation in response to metformin treatment involving mTORC1 inhibition.

miR-218-5p, miR-124-3p and miR-23b-3p act synergistically to modulate the expression of NACC1, proliferation, and apoptosis in C-33A and CaSki cells.

Background: In cervical cancer (CC), miR-218-5p, -124-3p, and -23b-3p act as tumor suppressors. These miRNAs have specific and common target genes that modulate apoptosis, proliferation, invasion, and migration; biological processes involved in cancer. Methods: miR-218-5p, -124-3p, and -23b-3p mimics were transfected into C-33A and CaSki cells, and RT-qPCR was used to quantify the level of each miRNA and NACC1. Proliferation was assessed by BrdU and apoptosis by Annexin V/PI. In the TCGA and The Human Protein Atlas databases, the level of NACC1 mRNA and protein (putative target of the three miRNAs) was analyzed in CC and normal tissue. The relationship of NACC1 with the overall survival in CC was analyzed in GEPIA2. NACC1 mRNA and protein levels were higher in CC tissues compared with cervical tissue without injury. Results: An increased expression of NACC1 was associated with lower overall survival in CC patients. The levels of miR-218-5p, -124-3p, and -23b-3p were lower, and NACC1 was higher in C-33A and CaSki cells compared to HaCaT cells. The increase of miR-218-5p, -124-3p, and -23b-3p induced a significant decrease in NACC1 mRNA. The transfection of the three miRNAs together caused more drastic changes in the level of NACC1, in the proliferation, and in the apoptosis with respect to the individual transfections of each miRNA. Conclusion: The results indicate that miR-218-5p, -124-3p, and -23b-3p act synergistically to decrease NACC1 expression and proliferation while promoting apoptosis in C-33A and CaSki cells. The levels of NACC1, miR-218-5p, -124-3p, and -23b-3p may be a potential prognostic indicator in CC.

Compounds Consisting of Quinazoline, Ibuprofen, and Amino Acids with Cytotoxic and Anti-Inflammatory Effects.

In this research work, a series of 16 quinazoline derivatives bearing ibuprofen and an amino acid were designed as inhibitors of epidermal growth factor receptor tyrosine kinase domain (EGFR-TKD) and cyclooxygenase-2 (COX-2) with the intention of presenting dual action in their biological behavior. The designed compounds were synthesized and assessed for cytotoxicity on epithelial cancer cells lines (AGS, A-431, MCF-7, MDA-MB-231) and epithelial non-tumorigenic cell line (HaCaT). From this evaluation, derivative 6 was observed to exhibit higher cytotoxic potency (IC50) than gefitinib (reference drug) on three cancer cell lines (0.034 µM in A-431, 2.67 µM in MCF-7, and 3.64 µM in AGS) without showing activity on the non-tumorigenic cell line (>100 µM). Furthermore, assessment of EGFR-TKD inhibition by 6 showed a discreet difference compared to gefitinib. Additionally, 6 was used to conduct an in vivo anti-inflammatory assay using the 12-O-tetradecanoylphorbol-3-acetate (TPA) method, and it was shown to be 5 times more potent than ibuprofen. Molecular dynamics studies of EGFR-TKD revealed interactions between compound 6 and M793. On the other hand, one significant interaction was observed for COX-2, involving S531. The RMSD graph indicated that the ligand remained stable in 50 ns.

Mutant p53 gain-of-function stimulates canonical Wnt signaling via PI3K/AKT pathway in colon cancer.

Aberrant canonical Wnt signaling is a hallmark of colon cancer. The TP53 tumor suppressor gene is altered in many solid tumors, including colorectal cancer, resulting in mutant versions of p53 (mut-p53) that lose their tumor suppressor capacities and acquire new-oncogenic functions (GOFs) critical for disease progression. Although the mechanisms related to mut-p53 GOF have been explored extensively, the relevance of mut-p53 in the canonical Wnt pathway is not well defined. This work investigated the influence of mut-p53 compared to wt-p53 in ß-catenin-dependent Wnt signaling. Using the TCGA public data from Pan-Cancer and the GEPIA2 platform, an in silico analysis of wt-p53 versus mut-p53 genotyped colorectal cancer patients showed that TP53 (p53) and CTNNB1 (ß-catenin) are significantly overexpressed in colorectal cancer, compared with normal tissue. Using p53 overexpression or p53 knockdown assays of wt-p53 or mut-p53, we found that while wt-p53 antagonizes canonical Wnt signaling, mut-p53 induces the opposite effect, improving the ß-catenin-dependent transcriptional activity and colony formation ability of colon cancer cells, which were both decreased by mut-p53 knockdown expression. The mechanism involved in mut-p53-induced activation of canonical Wnt appears to be via AKT-mediated phosphorylation of Ser 552 of ß-catenin, which is known to stabilize and enhance its transcriptional activity. We also found that while wt-p53 expression contributes to 5-FU sensitivity in colon cancer cells, the RITA p53 reactivating molecule counteracted the resistance against 5-FU in cells expressing mut-p53. Our results indicate that mut-p53 GOF acts as a positive regulator of canonical Wnt signaling and participates in the induction of resistance to 5-FU in colon cancer cells.

CD24+CD44+CD54+EpCAM+ gastric cancer stem cells predict tumor progression and metastasis: clinical and experimental evidence.

BACKGROUND: Gastric cancer (GC) is a leading cause of cancer-related deaths worldwide. Specific and thorough identification of cancer cell subsets with higher tumorigenicity and chemoresistance, such as cancer stem cells (CSCs), could lead to the development of new and promising therapeutic targets. For better CSC identification, a complete or extended surface marker phenotype is needed to provide increased specificity for new cell targeting approaches. Our goal is to identify and characterize a putative extended phenotype for CSCs derived from patients with GC before treatment, as well as to evaluate its clinical value. In addition, we aim to ensure that cells with this phenotype have stemness and self-renewal capabilities. METHODS: This is a cohort study including 127 treatment-naïve patients with GC who attended the Instituto Nacional de Cancerología. Multiparametric flow cytometry analysis was performed to determine the extended phenotype of cells derived from gastric biopsies. The tumorigenic capability of cells identified in patients was assessed in a zebrafish model. RESULTS: CD24+CD44+CD54+EpCAM+ cells were present in all treatment-naïve patients included, with a median abundance of 1.16% (0.57-1.89%). The percentage of CD24+CD44+CD54+EpCAM+ cells was categorized as high or low using 1.19% as the cutoff for the CD24+CD44+CD54+EpCAM+ cell subset. Additionally, a higher TNM stage correlated with a higher percentage of CD24+CD44+CD54+EpCAM+ cells (Rho coefficient 0.369; p < 0.0001). We also demonstrated that a higher percentage of CD24+CD44+CD54+EpCAM+ cells was positively associated with metastasis. The metastatic potential of these cells was confirmed in a zebrafish model. Ultimately, under our conditions, we conclude that CD24+CD44+CD54+EpCAM+ cells are true gastric cancer stem cells (GCSCs). CONCLUSION: The CD24+CD44+CD54+EpCAM+ cells present in tissue samples from patients are true GCSCs. This extended phenotype results in better and more specific characterization of these highly tumorigenic cells. The relative quantification of CD24+CD44+CD54+EpCAM+ cells has potential clinical value, as these cells are associated with metastatic disease, making their presence an additional prognostic marker and possibly a target for the design of new antineoplastic treatments in the era of precision oncology. Overall, the extended CD24+CD44+CD54+EpCAM+ phenotype of GCSCs could support their isolation for the study of their stemness mechanisms, leading to the identification of better molecular targets for the development of both new therapeutic approaches such as oncoimmunotherapy and new diagnostic and clinical prognostic strategies for GC.

The cross talk between gastric cancer stem cells and the immune microenvironment: a tumor-promoting factor.

Cross talk between cancer cells and the immune system is determinant for cancer progression. Emerging evidence demonstrates that GC characteristics such as metastasis, treatment resistance, and disease recurrence are associated with a tumor subpopulation called gastric cancer stem cells (GCSCs). However, the specific interaction between GCSCs and the immune microenvironment is still under investigation. Although immune evasion has been well described for cancer stem cells (CSCs), recent studies show that GCSCs can also regulate the immune system and even benefit from it. This review will provide an overview of bidirectional interactions between CSCs and immune cells in GC, compiling relevant data about how CSCs can induce leukocyte reprogramming, resulting in pro-tumoral immune cells that orchestrate promotion of metastasis, chemoresistance, tumorigenicity, and even increase in number of cancer cells with stem properties. Some immune cells studied are tumor-associated macrophages (TAMs), neutrophils, Th17 and T regulatory (Treg) cells, mesenchymal stem cells (MSCs), and cancer-associated fibroblasts (CAFs), as well as the signaling pathways involved in these pro-tumoral activities. Conversely, although there are cytotoxic leukocytes that can potentially eliminate GCSCs, we describe mechanisms for immune evasion in GCSCs and their clinical implications. Furthermore, we describe current available immunotherapy targeting GCSC-related markers as possible treatment for GC, discussing how the CSC-modified immune microenvironment can mitigate or inactivate these immunotherapies, limiting their effectiveness. Finally, we summarize key concepts and relevant evidence to understand the cross talk between GCSCs and the immune microenvironment as an important process for effective design of therapies against GCSCs that improve the outcome of patients with GC.

Anti-inflammatory and antitumor activities of the chloroform extract and anti-inflammatory effect of the three diterpenes isolated from Salvia ballotiflora Benth.

BACKGROUND: Drugs used for the treatment of diseases associated with chronic inflammation, such as cancer and rheumatoid arthritis have the potential to cause undesirable side-effects, which might result in patients ending treatment prematurely. However, plants are a viable option for the treatment of inflammatory diseases. In this study, we assessed the in vivo and in vitro anti-inflammatory activity, and the antitumor effects of the chloroform extract of Salvia ballotiflora (ECL). The pro-apoptotic effects of ECL in CT26 cells were also determined. METHODS: The chloroform extract of Salvia ballotiflora (ECL) was standardized using 19-deoxyicetexone (DEOX) as a phytochemical marker. The anti-inflammatory activity of ECL was determined on acute and chronic inflammatory models using the TPA-induced mouse ear edema assay. The antitumor activity of ECL was evaluated by the subcutaneous inoculation of CT26 cells on the back of Balb/c mice. In vitro CT26 cell death induced by ECL was determined by Annexin V/propidium iodide staining assay using flow cytometry. ECL and the diterpenes isolated from the chloroform extract included 19-deoxyicetexone (DEOX), icetexone (ICT), and 7,20-dihydroanastomosine (DAM), which were tested in LPS-stimulated J774A.1 macrophages to quantify pro-inflammatory cytokine levels. The in vitro anti-arthritic activity of ECL was determined using the bovine serum protein (BSP) denaturation assay. RESULTS: ECL exerted anti-inflammatory activities in acute (84% of inhibition, 2 mg/ear) and chronic models (62.71%, at 100 mg/kg). ECL showed antitumor activity at 200 mg/kg and 300 mg/kg, reducing tumor volume by 30 and 40%, respectively. ECL (9.5 µg/mL) induced in vitro apoptosis in CT26 cells by 29.1% (48 h of treatment) and 93.9% (72 h of treatment). ECL (10 µg/ml) decreased levels of NO (53.7%), pro-inflammatory cytokines IL-6 (44.9%), IL-1ß (71.9%), and TNF-α (40.1%), but increased the production of the anti-inflammatory cytokine IL-10 (44%). The diterpenes DEOX, ICT, and DAM decreased levels of NO (38.34, 47.63, 67.15%), IL-6 (57.84, 60.45, 44.26%), and TNF-α (38.90, 31.30, 32.83%), respectively. ECL showed in vitro antiarthritic activity (IC50 = 482.65 µg/mL). CONCLUSIONS: ECL exhibited anti-inflammatory and anti-tumor activities. Furthermore, the diterpenes DEOX, DAM, and ICT showed anti-inflammatory activity by reducing levels of NO, TNF-α, and IL-6.

ALDHHIGH Population Is Regulated by the AKT/ß-Catenin Pathway in a Cervical Cancer Model.

ALDH is an enzyme involved in different cellular processes, including cancer. It has been shown that a cellular subpopulation with high ALDH activity (ALDHHIGH) within a tumor is related to functional capabilities such as stemness, chemoresistance, and tumorigenicity. However, few studies have focused on determining the mechanisms behind ALDH activity within the cells. Previously, our group reported that ALDHHIGH cells have higher tumorigenicity in Cervical Cancer (CC) cell lines. Based on this, we were interested to know the molecular mediators of the ALDHHIGH cells, specifically ß-catenin, inasmuch as ß-catenin is regulated through different pathways, such as Wnt signaling, and that it acts as a transcriptional co-activator involved in cancer progression. In this work, we show that the increase in ALDHHIGH cell percentage is reverted by ß-catenin knockdown. Consistently, upon GSK3-ß inactivation, a negative regulator of ß-catenin, we observed an increase in ALDHHIGH cells. Additionally, we observed a low percentage of cells positive for Fzd receptor, suggesting that in our model there is a low capacity to respond to Wnt ligands. The analysis of ALDHHIGH cells in a sphere formation model demonstrated the active state of AKT. In accordance with this, impairment of AKT activity not only reduced ß-catenin active state, but also the percentage of ALDHHIGH cells. This corroborates that AKT acts upstream of ß-catenin, thus affecting the percentage of ALDHHIGH cells. In conclusion, our results show that ALDHHIGH cells are dependent on ß-catenin, in spite of the Wnt pathway seems to be dispensable, while AKT emerges as central player supporting a mechanism in this important axis that is not yet well known but its analysis improves our understanding of ALDH activity on CC.

Tumor microenvironment differences between primary tumor and brain metastases.

The present review aimed to discuss contemporary scientific literature involving differences between the tumor microenvironment (TME) in melanoma, lung cancer, and breast cancer in their primary site and TME in brain metastases (BM). TME plays a fundamental role in the behavior of cancer. In the process of carcinogenesis, cells such as fibroblasts, macrophages, endothelial cells, natural killer cells, and other cells can perpetuate and progress carcinogenesis via the secretion of molecules. Oxygen concentration, growth factors, and receptors in TME initiate angiogenesis and are examples of the importance of microenvironmental conditions in the performance of neoplastic cells. The most frequent malignant brain tumors are metastatic in origin and primarily originate from lung cancer, breast cancer, and melanoma. Metastatic cancer cells have to adhere to and penetrate the blood-brain barrier (BBB). After traversing BBB, these cells have to survive by producing various cytokines, chemokines, and mediators to modify their new TME. The microenvironment of these metastases is currently being studied owing to the discovery of new therapeutic targets. In these three types of tumors, treatment is more effective in the primary tumor than in BM due to several factors, including BBB. Understanding the differences in the characteristics of the microenvironment surrounding the primary tumor and their respective metastasis might help improve strategies to comprehend cancer.

Mutant p53 Gain-of-Function: Role in Cancer Development, Progression, and Therapeutic Approaches.

Frequent p53 mutations (mutp53) not only abolish tumor suppressor capacities but confer various gain-of-function (GOF) activities that impacts molecules and pathways now regarded as central for tumor development and progression. Although the complete impact of GOF is still far from being fully understood, the effects on proliferation, migration, metabolic reprogramming, and immune evasion, among others, certainly constitute major driving forces for human tumors harboring them. In this review we discuss major molecular mechanisms driven by mutp53 GOF. We present novel mechanistic insights on their effects over key functional molecules and processes involved in cancer. We analyze new mechanistic insights impacting processes such as immune system evasion, metabolic reprogramming, and stemness. In particular, the increased lipogenic activity through the mevalonate pathway (MVA) and the alteration of metabolic homeostasis due to interactions between mutp53 and AMP-activated protein kinase (AMPK) and Sterol regulatory element-binding protein 1 (SREBP1) that impact anabolic pathways and favor metabolic reprograming. We address, in detail, the impact of mutp53 over metabolic reprogramming and the Warburg effect observed in cancer cells as a consequence, not only of loss-of-function of p53, but rather as an effect of GOF that is crucial for the imbalance between glycolysis and oxidative phosphorylation. Additionally, transcriptional activation of new targets, resulting from interaction of mutp53 with NF-kB, HIF-1α, or SREBP1, are presented and discussed. Finally, we discuss perspectives for targeting molecules and pathways involved in chemo-resistance of tumor cells resulting from mutp53 GOF. We discuss and stress the fact that the status of p53 currently constitutes one of the most relevant criteria to understand the role of autophagy as a survival mechanism in cancer, and propose new therapeutic approaches that could promote the reduction of GOF effects exercised by mutp53 in cancer.

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.

Analysis of the dynamic aberrant landscape of DNA methylation and gene expression during arsenic-induced cell transformation.

Inorganic arsenic is a well-known carcinogen associated with several types of cancer, but the mechanisms involved in arsenic-induced carcinogenesis are not fully understood. Recent evidence points to epigenetic dysregulation as an important mechanism in this process; however, the effects of epigenetic alterations in gene expression have not been explored in depth. Using microarray data and applying a multivariate clustering analysis in a Gaussian mixture model, we describe the alterations in DNA methylation around the promoter region and the impact on gene expression in HaCaT cells during the transformation process caused by chronic exposure to arsenic. Using this clustering approach, the genes were grouped according to their methylation and expression status in the epigenetic landscape, and the changes that occurred during the cellular transformation were identified adequately. Thus, we present a valuable method for identifying epigenomic dysregulation.

Cancer Stem Cells from Tumor Cell Lines Activate the DNA Damage Response Pathway after Ionizing Radiation More Efficiently Than Noncancer Stem Cells.

Recently, a subpopulation of tumor cells, called cancer stem cells (CSC), has been characterized, and these have emerged as a major topic in cancer research. CSC are proposed to repair DNA damage more efficiently than the rest of tumor cells, resisting chemotherapy or radiotherapy and causing clinical recurrence and metastasis. We aimed to determine the molecular basis of radioresistance and first compared the response to ionizing radiation (IR) between cancer stem cell-enriched cultures grown as spheres and conventional tumor cell line cultures grown as monolayer, from HeLa and MCF-7 cancer cell lines. To verify that our sphere cultures were enriched in CSC, we evaluated the double staining of CD49f and ALDH activity for HeLa cells by flow cytometry. We then evaluated whether differences could exist in sensor elements in the DNA damage response pathway among these cultures. We found that CSC cultures showed less sensitivity to radiation than conventional tumor cell line cultures. We observed a higher baseline expression of activated response sensor proteins of DNA damage, such as ATM, H2A.X, and PARP1, in untreated CSC cultures. These findings provide the first evidence, to our knowledge, that DNA damage response sensor proteins are present and preferentially activated in CSC, as opposed to the bulk of cells in monolayer cultures. Likewise, they provide the basis for biological differences in response to IR between CSC and other tumor cell populations. Understanding the DNA damage response pathway may provide therapeutic targets to sensitize CSC to cytotoxic therapies to improve current cancer treatments.

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.

Molecular iodine inhibits the expression of stemness markers on cancer stem-like cells of established cell lines derived from cervical cancer.

BACKGROUND: Cancer stem cells (CSC) are characterized by deregulated self-renewal, tumorigenicity, metastatic potential, aberrant stemness signaling pathways, resistance to conventional therapy, and the ability to give rise to a progeny of proliferating cells that constitute the bulk of tumors. Targeting CSC will provide novel treatments for cancer. Different investigations have focused on developing complementary approaches that involve natural compounds that decrease chemo-resistance and reduce the side effects of conventional therapies. Since, it has been reported that molecular iodine (I2) exhibits antineoplastic effects and decreases tumor progression in some cancer models, we evaluated the potential effect of I2 on cell cultures enriched in cervical cancer stem-like cells. METHODS: HeLa and SiHa cervical cancer cells were treated with 200uM I2 for 24 h. After time, cells were cultured in CSC-conditioned medium (cervospheres) and viability assays were performed. Following, tumorigenic capabilities in cervospheres treated with I2 were evaluated in NOD/SCID mice. HeLa monolayer cells untreated and their respective cervosphere cells treated or untreated with 200 µM of I2 for 24 h were xenotransplanted subcutaneously at different amounts and mice were monitored for at least 2 months. RESULTS: In the present study, monolayer and CSC-enriched cultures (cervospheres) from cervical cancer-derived cell lines, HeLa and SiHa, showed that 200uM I2 supplementation inhibits proliferation of both and decreased their tumorigenic capacity, in vivo. This antineoplastic effect of I2 was accompanied by diminished expression of stemness markers including CD49f, CK17, OCT-4, NANOG, SOX2, and KLF4, as well as increased expression and activation of PPARγ receptors. CONCLUSIONS: All this data led us to suggest a clinical potential use of I2 for targeting CSC and improve current treatments against cervical cancer.

Regulation of Cellular Metabolism by High-Risk Human Papillomaviruses.

The alteration of glucose metabolism is one of the first biochemical characteristics associated with cancer cells since most of these cells increase glucose consumption and glycolytic rates even in the presence of oxygen, which has been called “aerobic glycolysis" or the Warburg effect. Human papillomavirus (HPV) is associated with approximately 5% of all human cancers worldwide, principally to cervical cancer. E6 and E7 are the main viral oncoproteins which are required to preserve the malignant phenotype. These viral proteins regulate the cell cycle through their interaction with tumor suppressor proteins p53 and pRB, respectively. Together with the viral proteins E5 and E2, E6 and E7 can favor the Warburg effect and contribute to radio- and chemoresistance through the increase in the activity of glycolytic enzymes, as well as the inhibition of the Krebs cycle and the respiratory chain. These processes lead to a fast production of ATP obtained by Warburg, which could help satisfy the high energy demands of cancer cells during proliferation. In this way HPV proteins could promote cancer hallmarks. However, it is also possible that during an early HPV infection, the Warburg effect could help in the achievement of an efficient viral replication.