Cancer stem cells and signaling pathways in radioresistance

Deciphering colorectal cancer radioresistance and immune microrenvironment: unraveling the role of EIF5A through single-cell RNA sequencing and machine learning

Background

Radiotherapy (RT) is a critical component of treatment for locally advanced rectal cancer (LARC), though patient response varies significantly. The variability in treatment outcomes is partly due to the resistance conferred by cancer stem cells (CSCs) and tumor immune microenvironment (TiME). This study investigates the role of EIF5A in radiotherapy response and its impact on the CSCs and TiME.

Methods

Predictive models for preoperative radiotherapy (preRT) response were developed using machine learning, identifying EIF5A as a key gene associated with radioresistance. EIF5A expression was analyzed via bulk RNA-seq and single-cell RNA-seq (scRNA-seq). Functional assays and in vivo experiments validated EIF5A's role in radioresistance and TiME modulation.

Results

EIF5A was significantly upregulated in radioresistant colorectal cancer (CRC) tissues. EIF5A knockdown in CRC cell lines reduced cell viability, migration, and invasion after radiation, and increased radiation-induced apoptosis. Mechanistically, EIF5A promoted cancer stem cell (CSC) characteristics through the Hedgehog signaling pathway. Analysis of the TiME revealed that the radiation-resistant group had an immune-desert phenotype, characterized by low immune cell infiltration. In vivo experiments showed that EIF5A knockdown led to increased infiltration of CD8+ T cells and M1 macrophages, and decreased M2 macrophages and Tregs following radiation therapy, thereby enhancing the radiotherapy response.

Conclusion

EIF5A contributes to CRC radioresistance by promoting CSC traits via the Hedgehog pathway and modulating the TiME to an immune-suppressive state. Targeting EIF5A could enhance radiation sensitivity and improve immune responses, offering a potential therapeutic strategy to optimize radiotherapy outcomes in CRC patients.

Additional considerations in cancer cell radioresistance, integrin αvβ3 and thyroid hormones

BACKGROUND

The existence of a functional relationship between a certain thyroid hormone analogue and cancer cell radioresistance has been shown by Leith and coworkers. The hormone analogue with relevance to malignant cells' radioresistance is tetraiodothyroacetic acid (tetrac). Tetrac is the deaminated derivative of L-thyroxine (T4), the principal product of the thyroid gland. Preclinical studies demonstrated that tetrac and chemically modified tetrac (CMT), e.g. a fluorobenzyl-conjugated tetrac analogue, restores radiosensitivity in certain radioresistant tumor cells. Due to their molecular, physico-chemical, and biological properties, actions of CMT analogues are believed to be initiated at the thyroid hormone analogue receptor site on plasma membrane integrin αvβ3.

OBJECTIVE

To explore possible molecular mechanisms of the potentially therapeutically beneficial effect of CMT on cancer cells' sensitivity to radiation, we analyzed actions of CMT analogues on expression of selected sets of genes that have been previously implicated in radioresistance of malignant cells.

DISCUSSION AND CONCLUSIONS

In the current study, we report that genome-wide gene expression profiling analysis of human glioblastoma (GBM) and acute myelocytic leukemia (AML) cell lines exposed in vitro to noncytotoxic doses of CMT has identified decreased expression of discrete trios of genes each of which was previously linked to cancer cells' radioresistance. Following the CMT treatment in AML cells, expression of PARP9, PARP15 and STAT3 genes was significantly reduced, while in GBM cells, expression of PRKDC, EGFR and CCNDI was significantly decreased by the drug. Notably, a broader spectrum of genes implicated in cancer cells' radioresistance was observed in primary patient-derived GBM cells after the CMT treatment. Extensive additional experimental and clinical studies are indicated, including analyses of individual patient tumor genomics and of an array of different tumor types to define the sub-sets of tumors manifesting radioresistance in which tetrac-based agents may be expected to enhance therapeutic effects of radiation.

Cancer radioresistance is characterized by a differential lipid droplet content along the cell cycle

BACKGROUND

Cancer radiation treatments have seen substantial advancements, yet the biomolecular mechanisms underlying cancer cell radioresistance continue to elude full understanding. The effectiveness of radiation on cancer is hindered by various factors, such as oxygen concentrations within tumors, cells' ability to repair DNA damage and metabolic changes. Moreover, the initial and radiation-induced cell cycle profiles can significantly influence radiotherapy responses as radiation sensitivity fluctuates across different cell cycle stages. Given this evidence and our prior studies establishing a correlation between cancer radiation resistance and an increased number of cytoplasmic Lipid Droplets (LDs), we investigated if LD accumulation was modulated along the cell cycle and if this correlated with differential radioresistance in lung and bladder cell lines.

RESULTS

Our findings identified the S phase as the most radioresistant cell cycle phase being characterized by an increase in LDs. Analysis of the expression of perilipin genes (a family of proteins involved in the LD structure and functions) throughout the cell cycle also uncovered a unique gene cell cycle pattern.

CONCLUSIONS

In summary, although these results require further molecular studies about the mechanisms of radioresistance, the findings presented here are the first evidence that LD accumulation could participate in cancer cells' ability to better survive X-Ray radiation when cells are in the S phase. LDs can represent new players in the radioresistance processes associated with cancer metabolism. This could open new therapeutic avenues in which the use of LD-interfering drugs might enhance cancer sensitivity to radiation.

Emerging Role of Autophagy in Governing Cellular Dormancy, Metabolic Functions, and Therapeutic Responses of Cancer Stem Cells

Tumors are composed of heterogeneous populations of dysregulated cells that grow in specialized niches that support their growth and maintain their properties. Tumor heterogeneity and metastasis are among the major hindrances that exist while treating cancer patients, leading to poor clinical outcomes. Although the factors that determine tumor complexity remain largely unknown, several genotypic and phenotypic changes, including DNA mutations and metabolic reprograming provide cancer cells with a survival advantage over host cells and resistance to therapeutics. Furthermore, the presence of a specific population of cells within the tumor mass, commonly known as cancer stem cells (CSCs), is thought to initiate tumor formation, maintenance, resistance, and recurrence. Therefore, these CSCs have been investigated in detail recently as potential targets to treat cancer and prevent recurrence. Understanding the molecular mechanisms involved in CSC proliferation, self-renewal, and dormancy may provide important clues for developing effective therapeutic strategies. Autophagy, a catabolic process, has long been recognized to regulate various physiological and pathological processes. In addition to regulating cancer cells, recent studies have identified a critical role for autophagy in regulating CSC functions. Autophagy is activated under various adverse conditions and promotes cellular maintenance, survival, and even cell death. Thus, it is intriguing to address whether autophagy promotes or inhibits CSC functions and whether autophagy modulation can be used to regulate CSC functions, either alone or in combination. This review describes the roles of autophagy in the regulation of metabolic functions, proliferation and quiescence of CSCs, and its role during therapeutic stress. The review further highlights the autophagy-associated pathways that could be used to regulate CSCs. Overall, the present review will help to rationalize various translational approaches that involve autophagy-mediated modulation of CSCs in controlling cancer progression, metastasis, and recurrence.

SALL4 promotes cancer stem-like cell phenotype and radioresistance in oral squamous cell carcinomas via methyltransferase-like 3-mediated m6A modification

Radioresistance imposes a great challenge in reducing tumor recurrence and improving the clinical prognosis of individuals having oral squamous cell carcinoma (OSCC). OSCC harbors a subpopulation of CD44(+) cells that exhibit cancer stem-like cell (CSC) characteristics are involved in malignant tumor phenotype and radioresistance. Nevertheless, the underlying molecular mechanisms in CD44( + )-OSCC remain unclear. The current investigation demonstrated that methyltransferase-like 3 (METTL3) is highly expressed in CD44(+) cells and promotes CSCs phenotype. Using RNA-sequencing analysis, we further showed that Spalt-like transcription factor 4 (SALL4) is involved in the maintenance of CSCs properties. Furthermore, the overexpression of SALL4 in CD44( + )-OSCC cells caused radioresistance in vitro and in vivo. In contrast, silencing SALL4 sensitized OSCC cells to radiation therapy (RT). Mechanistically, we illustrated that SALL4 is a direct downstream transcriptional regulation target of METTL3, the transcription activation of SALL4 promotes the nuclear transport of β-catenin and the expression of downstream target genes after radiation therapy, there by activates the Wnt/β-catenin pathway, effectively enhancing the CSCs phenotype and causing radioresistance. Herein, this study indicates that the METTL3/SALL4 axis promotes the CSCs phenotype and resistance to radiation in OSCC via the Wnt/β-catenin signaling pathway, and provides a potential therapeutic target to eliminate radioresistant OSCC.

Cancer stem cells: a target for overcoming therapeutic resistance and relapse

Cancer stem cells (CSCs) are a small subset of cells in cancers that are thought to initiate tumorous transformation and promote metastasis, recurrence, and resistance to treatment. Growing evidence has revealed the existence of CSCs in various types of cancers and suggested that CSCs differentiate into diverse lineage cells that contribute to tumor progression. We may be able to overcome the limitations of cancer treatment with a comprehensive understanding of the biological features and mechanisms underlying therapeutic resistance in CSCs. This review provides an overview of the properties, biomarkers, and mechanisms of resistance shown by CSCs. Recent findings on metabolic features, especially fatty acid metabolism and ferroptosis in CSCs, are highlighted, along with promising targeting strategies. Targeting CSCs is a potential treatment plan to conquer cancer and prevent resistance and relapse in cancer treatment.

Anti-tumor Effect of High Doses of Carbon Ions and X-Rays during Irradiation of Ehrlich Ascites Carcinoma Cells Ex Vivo

The effect of carbon ions (12C) with the energy of 400 MeV/nucleon on the dynamics of induction and growth rate of solid tumors in mice under irradiation of Ehrlich ascites carcinoma cells (EAC) ex vivo at doses of 5-30 Gy relative to the action of equally effective doses of X-ray radiation was studied. The dynamics of tumor induction under the action of 12C and X-rays had a similar character and depended on the dose during 3 months of observation. The value of the latent period, both when irradiating cells with 12C and X-ray, increased with increasing dose, and the interval for tumor induction decreased. The rate of tumor growth after ex vivo irradiation of EAC cells was independent of either dose or type of radiation. The dose at which EAC tumors are not induced within 90 days was 30 Gy for carbon ions and 60 Gy for X-rays. The value of the relative biological effectiveness of carbon ions, calculated from an equally effective dose of 50% probability of tumors, was 2.59.

Molecular mechanisms of resveratrol as chemo and radiosensitizer in cancer

One of the primary diseases that cause death worldwide is cancer. Cancer cells can be intrinsically resistant or acquire resistance to therapies and drugs used for cancer treatment through multiple mechanisms of action that favor cell survival and proliferation, becoming one of the leading causes of treatment failure against cancer. A promising strategy to overcome chemoresistance and radioresistance is the co-administration of anticancer agents and natural compounds with anticancer properties, such as the polyphenolic compound resveratrol (RSV). RSV has been reported to be able to sensitize cancer cells to chemotherapeutic agents and radiotherapy, promoting cancer cell death. This review describes the reported molecular mechanisms by which RSV sensitizes tumor cells to radiotherapy and chemotherapy treatment.

Cancer Stem Cells and Glioblastoma: Time for Innovative Biomarkers of Radio-Resistance?

Despite countless papers in the field of radioresistance, researchers are still far from clearly understanding the mechanisms triggered in glioblastoma. Cancer stem cells (CSC) are important to the growth and spread of cancer, according to many studies. In addition, more recently, it has been suggested that CSCs have an impact on glioblastoma patients' prognosis, tumor aggressiveness, and treatment outcomes. In reviewing this new area of biology, we will provide a summary of the most recent research on CSCs and their role in the response to radio-chemotherapy in GB. In this review, we will examine the radiosensitivity of stem cells. Moreover, we summarize the current knowledge of the biomarkers of stemness and evaluate their potential function in the study of radiosensitivity.

Dysregulated Stem Cell Markers Musashi-1 and Musashi-2 are Associated with Therapy Resistance in Inflammatory Breast Cancer

BACKGROUND AND AIM

While preliminary evidence points to pro-tumorigenic roles for the Musashi (MSI) RNA-binding proteins Musashi-1 (MSI1) and Musashi-2 (MSI2) in some breast cancer subtypes, no data exist for inflammatory breast cancer (IBC).

METHODS

MSI gene expression was quantified in IBC SUM149PT cells. We then used small interfering RNA-based MSI1 and MSI2 double knockdown (DKD) to understand gene expression and functional changes upon MSI depletion. We characterized cancer stem cell characteristics, cell apoptosis and cell cycle progression via flow cytometry, mammospheres via spheroid assays, migration and proliferation via digital holographic microscopy, and cell viability using BrdU assays. Chemoresistance was determined for paclitaxel and cisplatin with MTT assays and radioresistance was assessed with clonogenic analyses. In parallel, we supported our in vitro data by analyzing publicly available patient IBC gene expression datasets.

RESULTS

MSI1 and MSI2 are upregulated in breast cancer generally and IBC specifically. MSI2 is more commonly expressed compared to MSI1. MSI DKD attenuated proliferation, cell cycle progression, migration, and cell viability while increasing apoptosis. Stem cell characteristics CD44(+)/CD24(-), TERT and Oct4 were associated with MSI expression in vivo and were decreased in vitro after MSI DKD as was ALDH expression and mammosphere formation. In vivo, chemoresistant tumors were characterized by MSI upregulation upon chemotherapy application. In vitro, MSI DKD was able to alleviate chemo- and radioresistance.

CONCLUSIONS

The Musashi RNA binding proteins are dysregulated in IBC and associated with tumor proliferation, cancer stem cell phenotype, chemo- and radioresistance. MSI downregulation alleviates therapy resistance and attenuates tumor proliferation in vitro.

Refining Classification of Cholangiocarcinoma Subtypes via Proteogenomic Integration Reveals New Therapeutic Prospects

BACKGROUND & AIMS

Intrahepatic cholangiocarcinomas (iCCs) are characterized by their rarity, difficult diagnosis, and overall poor prognosis. The iCC molecular classification for developing precision medicine strategies was investigated.

METHODS

Comprehensive genomic, transcriptomic, proteomic, and phosphoproteomic analyses were performed on treatment-naïve tumor samples from 102 patients with iCC who underwent surgical resection with curative intent. An organoid model was constructed for testing therapeutic potential.

RESULTS

Three clinically supported subtypes (stem-like, poorly immunogenic, and metabolism) were identified. NCT-501 (aldehyde dehydrogenase 1 family member A1 [ALDH1A1] inhibitor) exhibited synergism with nanoparticle albumin-bound-paclitaxel in the organoid model for the stem-like subtype. The oncometabolite dysregulations were associated with different clinical outcomes in the stem-like and metabolism subtypes. The poorly immunogenic subtype harbors the non-T-cell tumor infiltration. Integrated multiomics analysis not only reproduced the 3 subtypes but also showed heterogeneity in iCC.

CONCLUSIONS

This large-scale proteogenomic analysis provides information beyond that obtained with genomic analysis, allowing the functional impact of genomic alterations to be discerned. These findings may assist in the stratification of patients with iCC and in developing rational therapeutic strategies.

MAPKs in the early steps of senescence implemEMTation

Evidence is accumulating that the earliest stages of the DNA damage response can direct cells toward senescence instead of other cell fates. In particular, tightly regulated signaling through Mitogen-Activated Protein Kinases (MAPKs) in early senescence can lead to a sustained pro-survival program and suppress a pro-apoptotic program. Importantly, an epithelial-to-mesenchymal Transition (EMT)-like program appears essential for preventing apoptosis and favoring senescence following DNA damage. In this review, we discuss how MAPKs might influence EMT features to promote a senescent phenotype that increases cell survival at the detriment of tissue function.

Cancer stem cells (CSCs): key player of radiotherapy resistance and its clinical significance

Cancer stem cells (CSCs) are self-renewing and slow-multiplying micro subpopulations in tumour microenvironments. CSCs contribute to cancer's resistance to radiation (including radiation) and other treatments. CSCs control the heterogeneity of the tumour. It alters the tumour's microenvironment cellular singling and promotes epithelial-to-mesenchymal transition (EMT). Current research decodes the role of extracellular vesicles (EVs) and CSCs interlink in radiation resistance. Exosome is a subpopulation of EVs and originated from plasma membrane. It is secreted by several active cells. It involed in cellular communication and messenger of healthly and multiple pathological complications. Exosomal biological active cargos (DNA, RNA, protein, lipid and glycan), are capable to transform recipient cells' nature. The molecular signatures of CSCs and CSC-derived exosomes are potential source of cancer theranostics development. This review discusse cancer stem cells, radiation-mediated CSCs development, EMT associated with CSCs, the role of exosomes in radioresistance development, the current state of radiation therapy and the use of CSCs and CSCs-derived exosomes biomolecules as a clinical screening biomarker for cancer. This review gives new researchers a reason to keep an eye on the next phase of scientific research into cancer theranostics that will help mankind.

Review: Mechanisms and perspective treatment of radioresistance in non-small cell lung cancer

Radiotherapy is the major treatment of non-small cell lung cancer (NSCLC). The radioresistance and toxicity are the main obstacles that leading to therapeutic failure and poor prognosis. Oncogenic mutation, cancer stem cells (CSCs), tumor hypoxia, DNA damage repair, epithelial-mesenchymal transition (EMT), and tumor microenvironment (TME) may dominate the occurrence of radioresistance at different stages of radiotherapy. Chemotherapy drugs, targeted drugs, and immune checkpoint inhibitors are combined with radiotherapy to treat NSCLC to improve the efficacy. This article reviews the potential mechanism of radioresistance in NSCLC, and discusses the current drug research to overcome radioresistance and the advantages of Traditional Chinese medicine (TCM) in improving the efficacy and reducing the toxicity of radiotherapy.

NRP1 inhibition modulates radiosensitivity of medulloblastoma by targeting cancer stem cells

BACKGROUND

Medulloblastoma (MB) is the most common pediatric malignant brain tumor. Despite current therapies, the morbidity and recurrent risk remains significant. Neuropilin-1 receptor (NRP1) has been implicated in the tumor progression of MB. Our recent study showed that NRP1 inhibition stimulated MB stem cells differentiation. Consequently, we hypothesized that targeting NRP1 in medulloblastoma could improve current treatments.

METHODS

NRP1 inhibition with a novel peptidomimetic agent, MR438, was evaluated with radiotherapy (RT) in MB models (DAOY, D283-Med and D341-Med) in vitro on cancer stem-like cells as well as in vivo on heterotopic and orthotopic xenografts.

RESULTS

We show that NRP1 inhibition by MR438 radiosensitizes MB stem-like cells in vitro. In heterotopic DAOY models, MR438 improves RT efficacy as measured by tumor growth and mouse survival. In addition, clonogenic assays after tumor dissociation showed a significant reduction in cancer stem cells with the combination treatment. In the same way, a benefit of the combined therapy was observed in the orthotopic model only for a low cumulative irradiation dose of 10 Gy but not for 20 Gy.

CONCLUSIONS

Finally, our results demonstrated that targeting NRP1 with MR438 could be a potential new strategy and could limit MB progression by decreasing the stem cell number while reducing the radiation dose.

The Molecular and Cellular Strategies of Glioblastoma and Non-Small-Cell Lung Cancer Cells Conferring Radioresistance

Ionizing radiation (IR) has been shown to play a crucial role in the treatment of glioblastoma (GBM; grade IV) and non-small-cell lung cancer (NSCLC). Nevertheless, recent studies have indicated that radiotherapy can offer only palliation owing to the radioresistance of GBM and NSCLC. Therefore, delineating the major radioresistance mechanisms may provide novel therapeutic approaches to sensitize these diseases to IR and improve patient outcomes. This review provides insights into the molecular and cellular mechanisms underlying GBM and NSCLC radioresistance, where it sheds light on the role played by cancer stem cells (CSCs), as well as discusses comprehensively how the cellular dormancy/non-proliferating state and polyploidy impact on their survival and relapse post-IR exposure.

LncRNA SNHG5 promotes the proliferation and cancer stem cell-like properties of HCC by regulating UPF1 and Wnt-signaling pathway

The role of long noncoding RNA (lncRNAs) had been demonstrated in different types of cancer, including hepatocellular carcinoma. This study was intended to investigate the role of lncRNA small nucleolar RNA host gene 5 (SNHG5) in HCC proliferation and the liver CSC-like properties. Through functional experiments, we determined that knockdown of SNHG5 repressed HCC cell proliferation and CSC-like properties, while over-expression of SNHG5 promoted cell growth. At the same time, CSC markers (CD44, CD133, and ALDH1) and related transcription factors (OCT4, SOX2, and NANOG) were downregulated when SNHG5 was knocked down. Mechanically, RNA immunoprecipitation (RIP) and RNA pulldown assay showed that SNHG5 regulated the proliferation and CSC-like properties of HCC by binding UPF1. Further investigations showed that expression of critical components of Wnt/β-catenin pathway (β-catenin, TCF4, c-myc, cyclinD1, and c-Jun) were upregulated with depletion of UPF1 in liver CSCs, which were downregulated with depletion of SNHG5. After use of the inhibitor of Wnt/β-catenin pathway, the formation of liver CSCs sphere decreased. Taken together, SNHG5 plays a critical role to promote HCC cell proliferation and cancer stem cell-like properties via UPF1 and Wnt/β-catenin pathway.

Potential association factors for developing effective peptide-based cancer vaccines

Peptide-based cancer vaccines have been shown to boost immune systems to kill tumor cells in cancer patients. However, designing an effective T cell epitope peptide-based cancer vaccine still remains a challenge and is a major hurdle for the application of cancer vaccines. In this study, we constructed for the first time a library of peptide-based cancer vaccines and their clinical attributes, named CancerVaccine (https://peptidecancervaccine.weebly.com/). To investigate the association factors that influence the effectiveness of cancer vaccines, these peptide-based cancer vaccines were classified into high (HCR) and low (LCR) clinical responses based on their clinical efficacy. Our study highlights that modified peptides derived from artificially modified proteins are suitable as cancer vaccines, especially for melanoma. It may be possible to advance cancer vaccines by screening for HLA class II affinity peptides may be an effective therapeutic strategy. In addition, the treatment regimen has the potential to influence the clinical response of a cancer vaccine, and Montanide ISA-51 might be an effective adjuvant. Finally, we constructed a high sensitivity and specificity machine learning model to assist in designing peptide-based cancer vaccines capable of providing high clinical responses. Together, our findings illustrate that a high clinical response following peptide-based cancer vaccination is correlated with the right type of peptide, the appropriate adjuvant, and a matched HLA allele, as well as an appropriate treatment regimen. This study would allow for enhanced development of cancer vaccines.

Prediction of Response to Radiotherapy by Characterizing the Transcriptomic Features in Clinical Tumor Samples across 15 Cancer Types

Purpose

Radiotherapy (RT) is one of the major cancer treatments. However, the responses to RT vary among individual patients, partly due to the differences of the status of gene expression and mutation in tumors of patients. Identification of patients who will benefit from RT will improve the efficacy of RT. However, only a few clinical biomarkers were currently used to predict RT response. Our aim is to obtain gene signatures that can be used to predict RT response by analyzing the transcriptome differences between RT responder and nonresponder groups.

Materials and Methods

We obtained transcriptome data of 1664 patients treated with RT from the TCGA database across 15 cancer types. First, the genes with a significant difference between RT responder (R group) and nonresponder groups (PD group) were identified, and the top 100 genes were used to build the gene signatures. Then, we developed the predictive model based on binary logistic regression to predict patient response to RT.

Results

We identified a series of differentially expressed genes between the two groups, which are involved in cell proliferation, migration, invasion, EMT, and DNA damage repair pathway. Among them, MDC1, UCP2, and RBM45 have been demonstrated to be involved in DNA damage repair and radiosensitivity. Our analysis revealed that the predictive model was highly specific for distinguishing the R and PD patients in different cancer types with an area under the curve (AUC) ranging from 0.772 to 0.972. It also provided a more accurate prediction than that from a single-gene signature for the overall survival (OS) of patients.

Conclusion

The predictive model has a potential clinical application as a biomarker to help physicians create optimal treatment plans. Furthermore, some of the genes identified here may be directly involved in radioresistance, providing clues for further studies on the mechanism of radioresistance.

Compound Kushen injection inhibits EMT of gastric cancer cells via the PI3K/AKT pathway

Background

The effective components contained in compound Kushen injection (CKI) and the genes and signalling pathways related to gastric cancer (GC) were analyzed through the network pharmacology method of traditional Chinese medicine, and various possible mechanisms by which CKI affects the proliferation, differentiation, survival, and metastasis of GC cells were discussed. The PI3K/AKT signalling pathway is considered to be one of the most important pathways targeted by CKI in the regulation of GC cells. The implementation of related cell experiments also confirmed the information we revealed.

Methods

Effective drug components of Kushen and Baituling in CKI were identified from the Traditional Chinese Medicine Systems Pharmacology Database (TCMSP). Genes related to GC were identified using the GENECARD and OMIM databases. The common target genes related to the effective components of the drug and GC were identified using the intersection method and visualized using software. A protein–protein interaction network (PPI) was established using STRING online software to confirm the key genes. Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to predict the key pathways of CKI in GC treatment. BGC-803 and MKN-28 GC cells were used to verify the signalling pathway. Cell proliferation, apoptosis, migration ability, and invasion ability were assessed using CCK8, flow cytometry, scratch, and transwell assays. Immunofluorescence assays and western blotting were used to detect the expression of related proteins.

Results

CKI regulated GC cells through 35 effective drug components of GC-related target genes. In total, 194 genes were common targets of CKI and GC. The most significant function of the enriched genes was DNA-binding transcription activator activity as demonstrated by GO enrichment analysis. The metabolic pathway with the highest enrichment was the PI3K/AKT signalling pathway as demonstrated by KEGG enrichment analysis. Our cell experimental evidence also shows that CKI inhibits GC cell growth and migration and induce GC cell apoptosis. In addition, CKI inhibits the EMT process in GC cells through the PI3K/AKT signalling pathway.

Conclusion

AKT1 is a key gene for CKI treatment of GC. CKI inhibited GC cell growth and migration and induced GC cell apoptosis. In addition, CKI regulated the EMT process in GC cells through the PI3K/AKT signalling pathway.

The effect of chromosome abnormalities on expression of SnoRNA in radioresistant and radiosensitive cell lines after irradiation

In this paper, we have studied the role of chromosomal abnormalities in the expression of small nucleolar RNAs (snoRNAs) of radioresistant (K562) and radiosensitive (HL-60) leukemia cell line. Cells were exposed to an X-ray dose of 4 Gy. SnoRNA expression was investigated using NGS sequencing. The distribution of expressed snoRNAs on chromosomes has been found to be different for two cell lines. The most significant differences in the expression of snoRNAs were found in the K562 cell line based on the analysis of the dynamics of log2fc values. The type of clustering, the number and type of snoRNAs slightly differed in the chromosomes with trisomy and monosomy and had a pronounced difference in pairs with marker chromosomes in both cell lines. In this study, we have demonstrated that chromosomal abnormalities alter the expression of snoRNA after irradiation. Trisomies and monosomies do not have such a noticeable effect on the expression of snoRNAs as the presence of marker chromosomes.

Factors and molecular mechanisms of radiation resistance in cancer cells

PURPOSE

The aim of this work is to review the published studies on radiation resistance mechanisms and molecular markers involved in different tumors. The revision has been focused in the last 5 years (2016-2021).

CONCLUSIONS

Radioresistance is a cause of concern as it causes failure of radiation therapy and subsequent tumor relapse. Combination chemotherapy and radiation therapy are clinically successful in treating many types of tumors. Despite continued improvements in cancer treatment, locoregional recurrence or metastatic spread continues to occur in a high proportion of patients after being treated with radiation therapy or combination treatments. There is strong evidence that cancer stem cells contribute to radiation resistance, contributing to treatment failure. The mechanisms of radiation resistance in different tumors are not fully understood. A better understanding of cancer stem cells and the associated signaling pathways that regulate radiation resistance will open up new strategies for treating cancer by radiation therapy. Radiation can damage malignant cells mainly by the induction of DNA double strand breaks. However, in some tumors appear resistant cells that repopulate the tumor following therapy leading over time to the failure of the treatment. Native mechanisms and induced pathways, are the cause of radiation resistance. It has been described that numerous molecular markers acting through numerous mechanisms of action involved in radiation resistance, such as apoptosis resistance, alterations of cell growth, proliferation and DNA repair, hypoxia, increase in invasiveness and migration capacity, cell cycle alterations and expression of heat shock proteins, among others. Therefore, resistance to radiation is a multifactorial phenomenon that, in different cell types, it occurs through different regulatory mechanisms in which different molecules intervene. Resistance can be acquired by altering different regulatory pathways in different tumors. The knowledge of radiation resistance markers could help in the classification and treatment of patients with more aggressive tumors.

Molecular mechanism of therapeutic approaches for human gastric cancer stem cells

Gastric cancer (GC) is a primary cause of cancer-related mortality worldwide, and even after therapeutic gastrectomy, survival rates remain poor. The presence of gastric cancer stem cells (GCSCs) is thought to be the major reason for resistance to anticancer treatment (chemotherapy or radiotherapy), and for the development of tumor recurrence, epithelial–mesenchymal transition, and metastases. Additionally, GCSCs have the capacity for self-renewal, differentiation, and tumor initiation. They also synthesize antiapoptotic factors, demonstrate higher performance of drug efflux pumps, and display cell plasticity abilities. Moreover, the tumor microenvironment (TME; tumor niche) that surrounds GCSCs contains secreted growth factors and supports angiogenesis and is thus responsible for the maintenance of the growing tumor. However, the genesis of GCSCs is unclear and exploration of the source of GCSCs is essential. In this review, we provide up-to-date information about GCSC-surface/intracellular markers and GCSC-mediated pathways and their role in tumor development. This information will support improved diagnosis, novel therapeutic approaches, and better prognosis using GCSC-targeting agents as a potentially effective treatment choice following surgical resection or in combination with chemotherapy and radiotherapy. To date, most anti-GCSC blockers when used alone have been reported as unsatisfactory anticancer agents. However, when used in combination with adjuvant therapy, treatment can improve. By providing insights into the molecular mechanisms of GCSCs associated with tumors in GC, the aim is to optimize anti-GCSCs molecular approaches for GC therapy in combination with chemotherapy, radiotherapy, or other adjuvant treatment.

Cabazitaxel suppresses the proliferation and promotes the apoptosis and radiosensitivity of castration-resistant prostate cancer cells by inhibiting PI3K/AKT pathway

BACKGROUND

Cabazitaxel has been applied to the treatment of castration-resistant prostate cancer (CRPC), but the molecular mechanism remained to be fully understood.

METHODS

After treatment with Cabazitaxel alone or in combination with ionizing radiation (IR), CRPC cell viability, proliferation and apoptosis were determined by Cell Counting Kit-8 (CCK-8) assay, colony formation, and flow cytometry, respectively. Tumor volume was measured after the establishment of animal xenograft model. Relative expressions of proteins related to apoptosis (B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), and cleaved caspase 3) and phosphoinositide 3-kinase (PI3K)/AKT pathway were measured by Western blot, and the phosphorylated-PI3K/PI3K and p-AKT/AKT ratios were determined as well.

RESULTS

Cell viability and proliferation were suppressed, and apoptosis was promoted in CRPC cells after Cabazitaxel treatment alone, accompanied with upregulated expressions of Bax and cleaved caspase 3 and downregulated Bcl-2 expression. Also, a single treatment with Cabazitaxel resulted in suppression of PI3K/AKT pathway activation, along with downregulated expressions of p-PI3K and p-AKT and a reduced ratio of p-PI3K/PI3K to p-AKT/AKT. Meanwhile, Cabazitaxel enhanced the effects of IR on suppressing survival and promoting apoptosis in CRPC cells through downregulating Bcl-2 and upregulating Bax and cleaved caspase 3. However, Cabazitaxel suppressed IR-induced PI3K/AKT pathway activation via downregulating p-PI3K and p-AKT, leading to a reduced ratio of p-PI3K/PI3K to p-AKT/AKT. Furthermore, Cabazitaxel further promoted the effects of IR on suppressing tumor growth in vivo.

CONCLUSION

Cabazitaxel inhibited the proliferation and promoted the apoptosis and radiosensitivity of CRPC cells, which is related to the suppression of PI3K/AKT pathway, providing a therapeutic method for CRPC in clinical practice.

ABT-737, a BH3 Mimetic, Enhances the Therapeutic Effects of Ionizing Radiation in K-ras Mutant Non-Small Cell Lung Cancer Preclinical Model

PURPOSE

Tumor radioresistance and dose-limiting toxicity restrict the curative potential of radiotherapy, requiring novel approaches to overcome the limitations and augment the efficacy. Here, we investigated the effects of signal transducer and activator of transcription 3 (STAT3) activation and autophagy induction by irradiation on antiapoptotic proteins and the effectiveness of the BH3 mimetic ABT-737 as a radiosensitizer using K-ras mutant non-small cell lung cancer (NSCLC) cells and a Kras^G12D:p53^fl/fl mouse (KP mouse) model.

MATERIALS AND METHODS

A549 and H460 cells were irradiated, and the expression of Bcl-2 family proteins, JAK/STAT transcriptional pathway, and autophagic pathway were evaluated by immunoblotting. The radiosensitizing effects of ABT-737 were evaluated using A549 and H460 cell lines with clonogenic assays and also by a KP mouse model with microcomputed tomography and immunohistochemistry.

RESULTS

In A549 and H460 cells and mouse lung tissue, irradiation-induced overexpression of the antiapoptotic molecules Bcl-xL, Bcl-2, Bcl-w, and Mcl-1 through JAK/STAT transcriptional signaling induced dysfunction of the autophagic pathway. After treatment with ABT-737 and exposure to irradiation, the number of surviving clones in the cotreatment group was significantly lower than that in the group treated with radiation or ABT-737 alone. In the KP mouse lung cancer model, cotreatment with ABT-737 and radiation-induced significant tumor regression; however, body weight changes in the combination group were not significantly different, suggesting that combination treatment did not cause systemic toxicity.

CONCLUSION

These findings supported the radiosensitizing activity of ABT-737 in preclinical models, and suggested that clinical trials using this strategy may be beneficial in K-ras mutant NSCLC.

Silencing of Fused Toes Homolog (FTS) Increases Radiosensitivity to Carbon-Ion Through Downregulation of Notch Signaling in Cervical Cancer Cells

The effects of Carbon ion radiation (C-ion) alone or in combination with fused toes homolog (FTS) silencing on Notch signaling were investigated in uterine cervical cancer cell lines (ME180 and CaSki). In both cell lines, upon irradiation with C-ion, the expression of Notch signaling molecules (Notch1, 2, 3 and cleaved Notch1), γ-secretase complex molecules and FTS was upregulated dose-dependently (1, 2 and 4 Gy) except Notch1 in ME180 cells where the change in expression was not significant. However, overexpression of these molecules was attenuated upon silencing of FTS. The spheroid formation, expression of stem cell markers (OCT4A, Sox2 and Nanog) and clonogenic cell survival were reduced by the combination as compared to FTS silencing or C-ion irradiation alone. Additionally, immunoprecipitation and immunofluorescence assay revealed interaction and co-localization of FTS with Notch signaling molecules. In conclusion, FTS silencing enhances the radio-sensitivity of the cervical cancer cells to C-ion by downregulating Notch signaling molecules and decreasing the survival of cancer stem cells.

miR-29b-3p Increases Radiosensitivity in Stemness Cancer Cells via Modulating Oncogenes Axis

Radioresistance conferred by cancer stem cells (CSCs) is the principal cause of the failure of cancer radiotherapy. Eradication of CSCs is a prime therapeutic target and a requirement for effective radiotherapy. Three dimensional (3D) cell-cultured model could mimic the morphology of cells in vivo and induce CSC properties. Emerging evidence suggests that microRNAs (miRNAs) play crucial roles in the regulation of radiosensitivity in cancers. In this study, we aim to investigate the effects of miRNAs on the radiosensitivity of 3D cultured stem-like cells. Using miRNA microarray analysis in 2D and 3D cell culture models, we found that the expression of miR-29b-3p was downregulated in 3D cultured A549 and MCF7 cells compared with monolayer (2D) cells. Clinic data analysis from The Cancer Genome Atlas database exhibited that miR-29b-3p high expression showed significant advantages in lung adenocarcinoma and breast invasive carcinoma patients’ prognosis. The subsequent experiments proved that miR-29b-3p overexpression decreased the radioresistance of cells in 3D culture and tumors in vivo through interfering kinetics process of DNA damage repair and inhibiting oncogenes RBL1, PIK3R1, AKT2, and Bcl-2. In addition, miR-29b-3p knockdown enhanced cancer cells invasion and migration capability. MiR-29b-3p overexpression decreased the stemness of 3D cultured cells. In conclusion, our results demonstrate that miR-29b-3p could be a sensitizer of radiation killing in CSC-like cells via inhibiting oncogenes expression. MiR-29b-3p could be a novel therapeutic candidate target for radiotherapy.

Aluminium (III) phthalocyanine chloride tetrasulphonate is an effective photosensitizer for the eradication of lung cancer stem cells

Cancer stem cells (CSCs) are considered to contribute to the recurrence of lung cancer due to their stem-like nature and the involvement of genetic markers associated with drug efflux, regeneration and metastases. Photodynamic therapy (PDT) is a cost-effective and non-invasive therapeutic application that can act as an alternative therapy for lung cancer when considering CSC involvement. Stem-like cells derived from the A549 lung cancer cell line, positive for CD133, CD56 and CD44 antigen markers, were characterized, intracellular localization of aluminium (III) phthalocyanine chloride tetrasulphonate (AlPcS₄Cl) determined and its anti-cancer PDT effects were evaluated. Results confirmed that isolated cells were stem cell-like and subcellular localization of AlPcS₄Cl in integral organelles involved in cell homeostasis supported the destruction of CSC. AlPcS₄Cl's effectivity was demonstrated with CSC eradication showing a significant increase in cytotoxicity and cell death via apoptosis, caused by a decrease in mitochondrial membrane potential. PDT could serve as a palliative treatment for lung cancer and improve prognosis by elimination of lung CSCs.

A radiosensitizer, gallotannin-rich extract from Bouea macrophylla seeds, inhibits radiation-induced epithelial-mesenchymal transition in breast cancer cells

Background

Radioresistance can pose a significant obstacle to the effective treatment of breast cancers. Epithelial–mesenchymal transition (EMT) is a critical step in the acquisition of stem cell traits and radioresistance. Here, we investigated whether Maprang seed extract (MPSE), a gallotannin-rich extract of seed from Bouea macrophylla Griffith, could inhibit the radiation-induced EMT process and enhance the radiosensitivity of breast cancer cells.

Methods

Breast cancer cells were pre-treated with MPSE before irradiation (IR), the radiosensitizing activity of MPSE was assessed using the colony formation assay. Radiation-induced EMT and stemness phenotype were identified using breast cancer stem cells (CSCs) marker (CD24^−/low/CD44⁺) and mammosphere formation assay. Cell motility was determined via the wound healing assay and transwell migration. Radiation-induced cell death was assessed via the apoptosis assay and SA-β-galactosidase staining for cellular senescence. CSCs- and EMT-related genes were confirmed by real-time PCR (qPCR) and Western blotting.

Results

Pre-treated with MPSE before irradiation could reduce the clonogenic activity and enhance radiosensitivity of breast cancer cell lines with sensitization enhancement ratios (SERs) of 2.33 and 1.35 for MCF7 and MDA-MB231cells, respectively. Pretreatment of breast cancer cells followed by IR resulted in an increased level of DNA damage maker (γ-H2A histone family member) and enhanced radiation-induced cell death. Irradiation induced EMT process, which displayed a significant EMT phenotype with a down-regulated epithelial marker E-cadherin and up-regulated mesenchymal marker vimentin in comparison with untreated breast cancer cells. Notably, we observed that pretreatment with MPSE attenuated the radiation-induced EMT process and decrease some stemness-like properties characterized by mammosphere formation and the CSC marker. Furthermore, pretreatment with MPSE attenuated the radiation-induced activation of the pro-survival pathway by decrease the expression of phosphorylation of ERK and AKT and sensitized breast cancer cells to radiation.

Conclusion

MPSE enhanced the radiosensitivity of breast cancer cells by enhancing IR-induced DNA damage and cell death, and attenuating the IR-induced EMT process and stemness phenotype via targeting survival pathways PI3K/AKT and MAPK in irradiated breast cancer cells. Our findings describe a novel strategy for increasing the efficacy of radiotherapy for breast cancer patients using a safer and low-cost natural product, MPSE.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03363-6.

High FRMD3 expression is prognostic for worse survival in rectal cancer patients treated with CCRT

BACKGROUND

Rectal cancer patients can conceivably obtain relief from neoadjuvant concurrent chemoradiotherapy (CCRT) for downstaging before resection, but the stratification of risk and clinical outcomes remains challenging. Therefore, identifying effective predictive biomarkers offers clinicians the opportunity to individually tailor early interventions, which would help optimize therapy.

METHODS

Using a public rectal cancer transcriptome dataset (GSE35452), we focused on cytoskeletal protein binding (GO: 0008092)-related genes and identified FERM domain containing 3 (FRMD3) as the most significant differentially expressed gene associated with CCRT resistance. We gathered 172 tumor samples from rectal cancer patients treated with neoadjuvant CCRT accompanied by curative resection and estimated the expression level of FRMD3 using immunohistochemistry.

RESULTS

The results revealed that high FRMD3 immunoexpression was remarkably associated with advanced pre-CCRT and post-CCRT tumor status (p = 0.004 and p < 0.001), pre-CCRT and post-CCRT lymph node metastasis (both p < 0.001), more perineurial invasion (p = 0.023), and a smaller extent of tumor regression (p = 0.018). High FRMD3 immunoexpression was remarkably correlated with inferior disease-specific survival (DSS) (p = 0.0001), local recurrence-free survival (LRFS) (p = 0.0003), and metastasis-free survival (MeFS) (p = 0.0023) at the univariate level. Furthermore, in multivariate analysis, high FRMD3 immunoexpression remained independently predictive of inferior DSS (p = 0.002), LRFS (p = 0.005), and MeFS (p = 0.015).

CONCLUSION

These results suggest that high FRMD3 expression is related to advanced clinicopathological features and inferior therapeutic responses in rectal cancer patients treated with CCRT, validating the promising prognostic value of FRMD3 expression.

Combined Radiochemotherapy: Metalloproteinases Revisited

Besides cytotoxic DNA damage irradiation of tumor cells triggers multiple intra- and intercellular signaling processes, that are part of a multilayered, treatment-induced stress response at the unicellular and tumor pathophysiological level. These processes are intertwined with intrinsic and acquired resistance mechanisms to the toxic effects of ionizing radiation and thereby co-determine the tumor response to radiotherapy. Proteolysis of structural elements and bioactive signaling moieties represents a major class of posttranslational modifications regulating intra- and intercellular communication. Plasma membrane-located and secreted metalloproteinases comprise a family of metal-, usually zinc-, dependent endopeptidases and sheddases with a broad variety of substrates including components of the extracellular matrix, cyto- and chemokines, growth and pro-angiogenic factors. Thereby, metalloproteinases play an important role in matrix remodeling and auto- and paracrine intercellular communication regulating tumor growth, angiogenesis, immune cell infiltration, tumor cell dissemination, and subsequently the response to cancer treatment. While metalloproteinases have long been identified as promising target structures for anti-cancer agents, previous pharmaceutical approaches mostly failed due to unwanted side effects related to the structural similarities among the multiple family members. Nevertheless, targeting of metalloproteinases still represents an interesting rationale alone and in combination with other treatment modalities. Here, we will give an overview on the role of metalloproteinases in the irradiated tumor microenvironment and discuss the therapeutic potential of using more specific metalloproteinase inhibitors in combination with radiotherapy.

Caffeic Acid, Quercetin and 5-Fluorocytidine-Functionalized Au-Fe3O4 Nanoheterodimers for X-ray-Triggered Drug Delivery in Breast Tumor Spheroids

Au-Fe3O4 nanoheterodimers (NHD) were functionalized with the natural and synthetic anticancer drugs caffeic acid (CA), quercetin (Q) and 5-fluorocytidine (5FC). Their X-radiation dose-enhancing potential and chemotherapeutic efficacy for bimodal cancer therapy were investigated by designing multicellular tumor spheroids (MCTS) to in vitro avascular tumor models. MCTS were grown from the breast cancer cell lines MCF-7, MDA-MB-231, and MCF-10A. The MCF-7, MDA-MB-231 and MCF-10A MCTS were incubated with NHD-CA, NHD-Q, or NHD-5FC and then exposed to fractionated X-radiation comprising either a single 10 Gy dose, 2 daily single 5 Gy doses or 5 daily single 2 Gy doses. The NHD-CA, NHD-Q, and NHD-5FC affected the growth of X-ray irradiated and non-irradiated MCTS in a different manner. The impact of the NHDs on the glycolytic metabolism due to oxygen deprivation inside MCTS was assessed by measuring lactate secretion and glucose uptake by the MCTS. The NHD-CA and NHD-Q were found to act as X-radiation dose agents in MCF-7 MCTS and MDA-MB-231 MCTS and served as radioprotector in MCF-10A MCTS. X-ray triggered release of CA and Q inhibited lactate secretion and thereupon disturbed glycolytic reprogramming, whereas 5FC exerted their cytotoxic effects on both, healthy and tumor cells, after their release into the cytosol.

Non-Genomic Actions of Estrogens on the DNA Repair Pathways Are Associated With Chemotherapy Resistance in Breast Cancer

Estrogens have been implicated in the etiology of breast cancer for a long time. It has been stated that long-term exposure to estrogens is associated with a higher incidence of breast cancer, since estradiol (E₂) stimulates breast cell growth; however, its effect on DNA damage/repair is only starting to be investigated. Recent studies have documented that estrogens are able to modify the DNA damage response (DDR) and DNA repair mechanisms. On the other hand, it has been proposed that DDR machinery can be altered by estrogen signaling pathways, that can be related to cancer progression and chemoresistance. We have demonstrated that E₂ promotes c-Src activation and breast cancer cell motility, through a non-genomic pathway. This review discusses scientific evidence supporting this non-genomic mechanism where estrogen modifies the DNA repair pathways, and its relationship to potential causes of chemoresistance.

Prospects for Radiopharmaceuticals as Effective and Safe Therapeutics in Oncology and Challenges of Tumor Resistance to Radiotherapy

The rapid advances in nuclear medicine have resulted in significant advantages for the field of oncology. The focus is on the application of radiopharmaceuticals as therapeuticals. In addition, the latest developments in cell biology (the understanding of the cell structure, function, metabolism, genetics, signaling, transformation) have given a strong scientific boost to radiation oncology. In this regard, the article discusses what is soon going to be a new jump in radiation oncology based on the already accumulated considerable knowledge at the cellular level about the mechanisms of cell transformation and tumor progression, cell response to radiation, cell resistance to apoptosis and radiation and cell radio-sensitivity. The mechanisms of resistance of tumor cells to radiation and the genetically determined individual sensitivity to radiation in patients (which creates the risk of radiation-induced acute and late side effects) are the 2 major challenges to overcome in modern nuclear medicine. The paper focuses on these problems and makes a detailed summary of the significance of the differences in the ionizing properties of radiopharmaceuticals and the principle of their application in radiation oncology that will shed additional light on how to make the anti-cancer radiotherapies more efficient and safe, giving some ideas for optimizations.

The future potential of Annona muricata L. extract and its bioactive compounds as radiation sensitizing agent: proposed mechanisms based on a systematic review

Despite technological advances in cancer treatment, especially in radiotherapy, many efforts are being made in improving cancer cell radio-sensitivity to increase therapeutic ratio and overcome cancer cell radio-resistance. In the present review, we evaluated the anticancer mechanism of Annona muricata L. (AM) leaves extract and its bioactive compounds such as annonaceous acetogenins, annomuricin, annonacin, or curcumin; and further correlated them with the potential of the mechanism to increase or to reduce cancer cells radio-sensitivity based on literature investigation. We see that AM has a promising future potential as a radio-sensitizer agent.

Antitumor and Radiosensitizing Effects of Zinc Oxide-Caffeic Acid Nanoparticles against Solid Ehrlich Carcinoma in Female Mice

This study aimed to evaluate the anticancer and radio-sensitizing efficacy of Zinc Oxide-Caffeic Acid Nanoparticles (ZnO-CA NPs). ZnO-CA NPs were formulated by the conjugation of Zinc Oxide nanoparticles (ZnO NPs) with caffeic acid (CA) that were characterized by Fourier Transform Infrared Spectra (FT-IR), X-ray Diffractometer (XRD), and Transmission Electron Microscopy (TEM). In vitro anticancer potential of ZnO-CA NPs was evaluated by assessing cell viability in the human breast (MCF-7) and hepatocellular (HepG2) carcinoma cell lines. In vivo anticancer and radio-sensitizing effects of ZnO-CA NPs in solid Ehrlich carcinoma-bearing mice (EC mice) were also assessed. Treatment of EC mice with ZnO-CA NPs resulted in a considerable decline in tumor size and weight, down-regulation of B-cell lymphoma 2 (BCL2) and nuclear factor kappa B (NF-κB) gene expressions, decreased vascular cell adhesion molecule 1 (VCAM-1) level, downregulation of phosphorylated-extracellular-regulated kinase 1 and 2 (p-ERK1/2) protein expression, DNA fragmentation and a recognizable peak at sub-G0/G1 indicating dead cells' population in cancer tissues. Combined treatment of ZnO-CA NPs with γ-irradiation improved these effects. In conclusion: ZnO-CA NPs exhibit in-vitro as well as in-vivo antitumor activity, which is augmented by exposure of mice to γ-irradiation. Further explorations are warranted previous to clinical application of ZnO-CA NPs.

Mechanisms for Tuning Engineered Nanomaterials to Enhance Radiation Therapy of Cancer

Engineered nanomaterials that produce reactive oxygen species on exposure to X- and gamma-rays used in radiation therapy offer promise of novel cancer treatment strategies. Similar to photodynamic therapy but suitable for large and deep tumors, this new approach where nanomaterials acting as sensitizing agents are combined with clinical radiation can be effective at well-tolerated low radiation doses. Suitably engineered nanomaterials can enhance cancer radiotherapy by increasing the tumor selectivity and decreasing side effects. Additionally, the nanomaterial platform offers therapeutically valuable functionalities, including molecular targeting, drug/gene delivery, and adaptive responses to trigger drug release. The potential of such nanomaterials to be combined with radiotherapy is widely recognized. In order for further breakthroughs to be made, and to facilitate clinical translation, the applicable principles and fundamentals should be articulated. This review focuses on mechanisms underpinning rational nanomaterial design to enhance radiation therapy, the understanding of which will enable novel ways to optimize its therapeutic efficacy. A roadmap for designing nanomaterials with optimized anticancer performance is also shown and the potential clinical significance and future translation are discussed.

CSC Radioresistance: A Therapeutic Challenge to Improve Radiotherapy Effectiveness in Cancer

Radiotherapy (RT) is a modality of oncologic treatment that can be used to treat approximately 50% of all cancer patients either alone or in combination with other treatment modalities such as surgery, chemotherapy, immunotherapy, and therapeutic targeting. Despite the technological advances in RT, which allow a more precise delivery of radiation while progressively minimizing the impact on normal tissues, issues like radioresistance and tumor recurrence remain important challenges. Tumor heterogeneity is responsible for the variation in the radiation response of the different tumor subpopulations. A main factor related to radioresistance is the presence of cancer stem cells (CSC) inside tumors, which are responsible for metastases, relapses, RT failure, and a poor prognosis in cancer patients. The plasticity of CSCs, a process highly dependent on the epithelial–mesenchymal transition (EMT) and associated to cell dedifferentiation, complicates the identification and eradication of CSCs and it might be involved in disease relapse and progression after irradiation. The tumor microenvironment and the interactions of CSCs with their niches also play an important role in the response to RT. This review provides a deep insight into the characteristics and radioresistance mechanisms of CSCs and into the role of CSCs and tumor microenvironment in both the primary tumor and metastasis in response to radiation, and the radiobiological principles related to the CSC response to RT. Finally, we summarize the major advances and clinical trials on the development of CSC-based therapies combined with RT to overcome radioresistance. A better understanding of the potential therapeutic targets for CSC radiosensitization will provide safer and more efficient combination strategies, which in turn will improve the live expectancy and curability of cancer patients.

Defining lung cancer stem cells exosomal payload of miRNAs in clinical perspective

Since the first publication regarding the existence of stem cells in cancer [cancer stem cells (CSCs)] in 1994, many studies have been published providing in-depth information about their biology and function. This research has paved the way in terms of appreciating the role of CSCs in tumour aggressiveness, progression, recurrence and resistance to cancer therapy. Targeting CSCs for cancer therapy has still not progressed to a sufficient degree, particularly in terms of exploring the mechanism of dynamic interconversion between CSCs and non-CSCs. Besides the CSC scenario, the problem of cancer dissemination has been analyzed in-depth with the identification and isolation of microRNAs (miRs), which are now considered to be compelling molecular markers in the diagnosis and prognosis of tumours in general and specifically in patients with non-small cell lung cancer. Paracrine release of miRs via “exosomes” (small membrane vesicles (30-100 nm), the derivation of which lies in the luminal membranes of multi-vesicular bodies) released by fusion with the cell membrane is gaining popularity. Whether exosomes play a significant role in maintaining a dynamic equilibrium state between CSCs and non-CSCs and their mechanism of activity is as yet unknown. Future studies on CSC-related exosomes will provide new perspectives for precision-targeted treatment strategies.

Radiotherapy targeting cancer stem cells "awakens" them to induce tumour relapse and metastasis in oral cancer

Radiotherapy is one of the most common treatments for oral cancer. However, in the clinic, recurrence and metastasis of oral cancer occur after radiotherapy, and the underlying mechanism remains unclear. Cancer stem cells (CSCs), considered the “seeds” of cancer, have been confirmed to be in a quiescent state in most established tumours, with their innate radioresistance helping them survive more easily when exposed to radiation than differentiated cancer cells. There is increasing evidence that CSCs play an important role in recurrence and metastasis post-radiotherapy in many cancers. However, little is known about how oral CSCs cause tumour recurrence and metastasis post-radiotherapy. In this review article, we will first summarise methods for the identification of oral CSCs and then focus on the characteristics of a CSC subpopulation induced by radiation, hereafter referred to as “awakened” CSCs, to highlight their response to radiotherapy and potential role in tumour recurrence and metastasis post-radiotherapy as well as potential therapeutics targeting CSCs. In addition, we explore potential therapeutic strategies targeting these “awakened” CSCs to solve the serious clinical challenges of recurrence and metastasis in oral cancer after radiotherapy.

Cancer associated fibroblasts-derived exosomes contribute to radioresistance through promoting colorectal cancer stem cells phenotype

Radioresistance observed in patients with colorectal cancer (CRC) may be related to the presence of cancer stem cells (CSCs), but the underlying mechanism(s) remain unclear. Cancer-associated fibroblasts (CAFs) can regulate the stemness of cancer cells and tumor radiosensitivity. In addition, exosomes have been reported to modify treatment response by mediating cell-cell communication. In this study, we aimed to investigate whether exosomes derived from CAFs (CAF-exosomes) are involved in mediating resistance to radiotherapy in colorectal cancer and to explore the underlying mechanism. We found that CSCs were inherently resistant to cell death induced by radiotherapy. CAF-derived CM promoted clonogenicity and radioresistance of CRC cells. Further investigations revealed that exosomes isolated from CM induced the above effects whereas exosome-depleted CM (solution) was not able to induce clonogenicity and radioresistance. Finally, exosomes could activate transforming growth factor-β (TGF-β) signaling pathway and TGFβ1-neutralizing antibody inhibit this effect and decrease clonogenicity and expression levels of stemness genes. In conclusion,our findings suggest CAFs promote stemness of CRC cells and thus increase radiation resistance. Exosomes derived from CAFs play a crucial role through activating TGF-β signaling pathway in this process.

Proteins of Wnt signaling pathway in cancer stem cells of human glioblastoma

RATIONALE

Glioblastoma multiforme (GBM) is the most aggressive primary glial brain tumor. The prognosis for GBM patients is not favorable, with the median survival time being 15 months. Its treatment resistance is associated with GBM cell population having cancer stem cells (CSCs). Wnt/β-catenin signaling pathway is a strategically important molecular mechanism, providing proliferation of stem cells of all types. This study compares the expression levels of signaling pathway proteins in CD133(+) CSCs and CD133(-) differentiated glioblastoma cells (DGCs).

MATERIALS AND METHODS

the present study used U-87MG cells of human glioblastoma, the material was tested for mycoplasma contamination. High-performance liquid chromatography (HPLC) mass spectrometry was used for proteome analysis. Biological and molecular functions, signaling pathways and protein-protein interactions were analyzed using free-access databases: PubMed, PANTHER, Gene Ontology, Swiss-Prot and KEGG. Protein-protein interactions (PPIs) were analyzed using the STRING database (version 10).

RESULTS

There were identified 589 proteins with significantly changed expression in CD133+ CSCs, as compared with CD133-DGCs (P<0.05). Bioinformatics analysis allowed to attribute 134 differentially expressed proteins to 16 signaling pathways. A significant increase in expression of eight Wnt signaling pathway proteins (APC, CSNK1E, CSNK1A, CSNK2A2, CSNK2B, CTNNB1, DVL1, RUVBL) was detected, as well as four proteins of the non-canonical Wnt pathway-RHOA, ROCK2, RAC2, DAAM1. Special attention should be paid to β-catenin (CTNNB1) with more than 13.98-fold increase of expression in CSCs and Disheveled-associated activator of morphogenesis 1 (DAAM1) with 6.15-fold higher upregulation level.

CONCLUSION

proteins of Wnt/β-catenin signaling cascade are a prospective target for regulating CSCs activity.

The p53-53BP1-Related Survival of A549 and H1299 Human Lung Cancer Cells after Multifractionated Radiotherapy Demonstrated Different Response to Additional Acute X-ray Exposure

Radiation therapy is one of the main methods of treating patients with non-small cell lung cancer (NSCLC). However, the resistance of tumor cells to exposure remains the main factor that limits successful therapeutic outcome. To study the molecular/cellular mechanisms of increased resistance of NSCLC to ionizing radiation (IR) exposure, we compared A549 (p53 wild-type) and H1299 (p53-deficient) cells, the two NSCLC cell lines. Using fractionated X-ray irradiation of these cells at a total dose of 60 Gy, we obtained the survived populations and named them A549IR and H1299IR, respectively. Further characterization of these cells showed multiple alterations compared to parental NSCLC cells. The additional 2 Gy exposure led to significant changes in the kinetics of γH2AX and phosphorylated ataxia telangiectasia mutated (pATM) foci numbers in A549IR and H1299IR compared to parental NSCLC cells. Whereas A549, A549IR, and H1299 cells demonstrated clear two-component kinetics of DNA double-strand break (DSB) repair, H1299IR showed slower kinetics of γH2AX foci disappearance with the presence of around 50% of the foci 8 h post-IR. The character of H2AX phosphorylation in these cells was pATM-independent. A decrease of residual γH2AX/53BP1 foci number was observed in both A549IR and H1299IR compared to parental cells post-IR at extra doses of 2, 4, and 6 Gy. This process was accompanied with the changes in the proliferation, cell cycle, apoptosis, and the expression of ATP-binding cassette sub-family G member 2 (ABCG2, also designated as CDw338 and the breast cancer resistance protein (BCRP)) protein. Our study provides strong evidence that different DNA repair mechanisms are activated by multifraction radiotherapy (MFR), as well as single-dose IR, and that the enhanced cellular survival after MFR is reliant on both p53 and 53BP1 signaling along with non-homologous end-joining (NHEJ). Our results are of clinical significance as they can guide the choice of the most effective IR regimen by analyzing the expression status of the p53–53BP1 pathway in tumors and thereby maximize therapeutic benefits for the patients while minimizing collateral damage to normal tissue.

microRNAs identified in prostate cancer: Correlative studies on response to ionizing radiation

As the most frequently diagnosed non-skin cancer in men and a leading cause of cancer-related death, understanding the molecular mechanisms that drive treatment resistance in prostate cancer poses a significant clinical need. Radiotherapy is one of the most widely used treatments for prostate cancer, along with surgery, hormone therapy, and chemotherapy. However, inherent radioresistance of tumor cells can reduce local control and ultimately lead to poor patient outcomes, such as recurrence, metastasis and death. The underlying mechanisms of radioresistance have not been fully elucidated, but it has been suggested that miRNAs play a critical role. miRNAs are small non-coding RNAs that regulate gene expression in every signaling pathway of the cell, with one miRNA often having multiple targets. By fine-tuning gene expression, miRNAs are important players in modulating DNA damage response, cell death, tumor aggression and the tumor microenvironment, and can ultimately affect a tumor's response to radiotherapy. Furthermore, much interest has focused on miRNAs found in biofluids and their potential utility in various clinical applications. In this review, we summarize the current knowledge on miRNA deregulation after irradiation and the associated functional outcomes, with a focus on prostate cancer. In addition, we discuss the utility of circulating miRNAs as non-invasive biomarkers to diagnose, predict response to treatment, and prognosticate patient outcomes.

Cancer stem cell and mesenchymal cell cooperative actions in metastasis progression and hormone resistance in prostate cancer: Potential role of androgen and gonadotropin‑releasing hormone receptors (Review)

Prostate cancer (PCa) is the leading cause of male cancer‑associated mortality worldwide. Mortality is associated with metastasis and hormone resistance. Cellular, genetic and molecular mechanisms underlying metastatic progression and hormone resistance are poorly understood. Studies have investigated the local effects of gonadotropin‑releasing hormone (GnRH) analogs (used for androgen deprivation treatments) and the presence of the GnRH receptor (GnRH‑R) on PCa cells. Furthermore, cell subpopulations with stem‑like properties, or cancer stem cells, have been isolated and characterized using a cell culture system derived from explants of human prostate tumors. In addition, the development of preclinical orthotopic models of human PCa in a nonobese diabetic/severe combined immunodeficiency mouse model of compromised immunity has enabled the establishment of a reproducible system of metastatic progression in vivo. There is increasing evidence that metastasis is a complex process involving the cooperative actions of different cancer cell subpopulations, in which cancer stem‑like cells would be responsible for the final step of colonizing premetastatic niches. It has been hypothesized that PCa cells with stemness and mesenchymal signatures act cooperatively in metastatic progression and the inhibition of stemness genes, and that overexpression of androgen receptor (AR) and GnRH‑R decreases the rate the metastasis and sensitizes tumors to hormone therapy. The aim of the present review is to analyze the evidence regarding this cooperative process and the possible influence of stem‑like cell phenotypes, AR and GnRH‑R in metastatic progression and hormone resistance. These aspects may represent an important contribution in the understanding of the mechanisms underlying metastasis and hormone resistance in PCa, and potential routes to blocking these processes, enabling the development of novel therapies that would be particularly relevant for patients with metastatic and castration‑resistant PCa.

Role of telomeric RAP1 in radiation sensitivity modulation and its interaction with CSC marker KLF4 in colorectal cancer

Aims: Radiotherapy is predominantly used as one of the treatment modalities to treat local tumor in colorectal cancer (CRC). Hindrance in disease treatment can be attributed to radio-tolerance of cancer stem cells (CSCs) subsistence in the tumor. Understanding the radio-resistant property of CSCs might help in the accomplishment of targeted radiotherapy treatment and increased disease-free survival. Telomeric RAP1 contributes in modulation of various transcription factors leading to aberrant cell proliferation and tumor cell migration. Therefore, we investigated the role of RAP1 in maintaining resistance phenotype and acquired stemness in radio-resistant cells.Main methods: Characterization of HCT116 derived radio-resistant cell (HCT116RR) was performed by cell survival and DNA damage profiling. RAP1 silenced cells were investigated for DNA damage and expression of CSC markers through western blotting and Real-time PCR post-irradiation. Molecular docking and co-immunoprecipitation study were performed to investigate RAP1 and KLF4 interaction followed by RAP1 protein status profiling in CRC patient.Key findings: We established radio-resistant cells, which showed tolerance to radiotherapy and elevated expression of CSC markers along with RAP1. RAP1 silencing showed enhanced DNA damage and reduced expression of CSC markers post-irradiation. We observed strong physical interaction between RAP1 and KLF4 protein. Furthermore, higher RAP1 expression was observed in the tumor of CRC patients. Dataset analysis also revealed that high expression of RAP1 expression is associated with poor prognosis.Significance: We conclude that higher expression of RAP1 implicates its possible role in promoting radio-resistance in CRC cells by modulating DNA damage and CSC phenotype.

Targeting cancer stem cell pathways for cancer therapy

Since cancer stem cells (CSCs) were first identified in leukemia in 1994, they have been considered promising therapeutic targets for cancer therapy. These cells have self-renewal capacity and differentiation potential and contribute to multiple tumor malignancies, such as recurrence, metastasis, heterogeneity, multidrug resistance, and radiation resistance. The biological activities of CSCs are regulated by several pluripotent transcription factors, such as OCT4, Sox2, Nanog, KLF4, and MYC. In addition, many intracellular signaling pathways, such as Wnt, NF-κB (nuclear factor-κB), Notch, Hedgehog, JAK-STAT (Janus kinase/signal transducers and activators of transcription), PI3K/AKT/mTOR (phosphoinositide 3-kinase/AKT/mammalian target of rapamycin), TGF (transforming growth factor)/SMAD, and PPAR (peroxisome proliferator-activated receptor), as well as extracellular factors, such as vascular niches, hypoxia, tumor-associated macrophages, cancer-associated fibroblasts, cancer-associated mesenchymal stem cells, extracellular matrix, and exosomes, have been shown to be very important regulators of CSCs. Molecules, vaccines, antibodies, and CAR-T (chimeric antigen receptor T cell) cells have been developed to specifically target CSCs, and some of these factors are already undergoing clinical trials. This review summarizes the characterization and identification of CSCs, depicts major factors and pathways that regulate CSC development, and discusses potential targeted therapy for CSCs.