Informed by Cancer Stem Cells of Solid Tumors: Advances in Treatments Targeting Tumor-Promoting Factors and Pathways.

Cancer stem cells (CSCs) represent a subpopulation within tumors that promote cancer progression, metastasis, and recurrence due to their self-renewal capacity and resistance to conventional therapies. CSC-specific markers and signaling pathways highly active in CSCs have emerged as a promising strategy for improving patient outcomes. This review provides a comprehensive overview of the therapeutic targets associated with CSCs of solid tumors across various cancer types, including key molecular markers aldehyde dehydrogenases, CD44, epithelial cellular adhesion molecule, and CD133 and signaling pathways such as Wnt/ß-catenin, Notch, and Sonic Hedgehog. We discuss a wide array of therapeutic modalities ranging from targeted antibodies, small molecule inhibitors, and near-infrared photoimmunotherapy to advanced genetic approaches like RNA interference, CRISPR/Cas9 technology, aptamers, antisense oligonucleotides, chimeric antigen receptor (CAR) T cells, CAR natural killer cells, bispecific T cell engagers, immunotoxins, drug-antibody conjugates, therapeutic peptides, and dendritic cell vaccines. This review spans developments from preclinical investigations to ongoing clinical trials, highlighting the innovative targeting strategies that have been informed by CSC-associated pathways and molecules to overcome therapeutic resistance. We aim to provide insights into the potential of these therapies to revolutionize cancer treatment, underscoring the critical need for a multi-faceted approach in the battle against cancer. This comprehensive analysis demonstrates how advances made in the CSC field have informed significant developments in novel targeted therapeutic approaches, with the ultimate goal of achieving more effective and durable responses in cancer patients.

ALDH1A3 promotes invasion and metastasis in triple-negative breast cancer by regulating the plasminogen activation pathway.

Aldehyde dehydrogenase 1A3 (ALDH1A3) is a cancer stem cell marker that promotes metastasis. Triple-negative breast cancer (TNBC) progression has been linked to ALDH1A3-induced gene expression changes. To investigate the mechanism of ALDH1A3-mediated breast cancer metastasis, we assessed the effect of ALDH1A3 on the expression of proteases and the regulators of proteases that degrade the extracellular matrix, a process that is essential for invasion and metastasis. This revealed that ALDH1A3 regulates the plasminogen activation pathway; it increased the levels and activity of tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA). This resulted in a corresponding increase in the activity of serine protease plasmin, the enzymatic product of tPA and uPA. The ALDH1A3 product all-trans-retinoic acid similarly increased tPA and plasmin activity. The increased invasion of TNBC cells by ALDH1A3 was plasminogen-dependent. In patient tumours, ALDH1A3 and tPA are co-expressed and their combined expression correlated with the TNBC subtype, high tumour grade and recurrent metastatic disease. Knockdown of tPA in TNBC cells inhibited plasmin generation and lymph node metastasis. These results identify the ALDH1A3-tPA-plasmin axis as a key contributor to breast cancer progression.

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

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

Isolation of cancer stem cells from cultured breast cancer cells and xenografted breast tumors based on aldehyde dehydrogenase activity.

The heterogeneity of breast tumors is a major factor in the development, progression, and therapeutic response of breast cancer. In terms of therapy resistance, a subset of tumor cells commonly referred to as cancer stem cells (CSCs) or tumor initiating cells (TICs) have a prominent role. These cells have inherent increased tumorigenicity, self-renewal and differentiation capacity, and mechanisms for chemotherapy and radiation resistance. The importance of CSCs/TICs in cancer makes isolating and studying these cells via reliable methods critical. CSCs/TICs can be enriched for by discrete markers. Increased aldehyde dehydrogenase (ALDH) activity as detected by the AldefluorTM assay is a commonly used method. In this chapter, we describe the detailed methods for identification and isolation of putative CSCs/TICs from cultured cells and xenografted breast tumors using the AldefluorTM assay and describe the importance of the ALDH isoforms in breast cancer.

Breast Cancer Subtype-Specific miRNAs: Networks, Impacts, and the Potential for Intervention.

The regulatory and functional roles of non-coding RNAs are increasingly demonstrated as critical in cancer. Among non-coding RNAs, microRNAs (miRNAs) are the most well-studied with direct regulation of biological signals through post-transcriptional repression of mRNAs. Like the transcriptome, which varies between tissue type and disease condition, the miRNA landscape is also similarly altered and shows disease-specific changes. The importance of individual tumor-promoting or suppressing miRNAs is well documented in breast cancer; however, the implications of miRNA networks is less defined. Some evidence suggests that breast cancer subtype-specific cellular effects are influenced by distinct miRNAs and a comprehensive network of subtype-specific miRNAs and mRNAs would allow us to better understand breast cancer signaling. In this review, we discuss the altered miRNA landscape in the context of breast cancer and propose that breast cancer subtypes have distinct miRNA dysregulation. Further, given that miRNAs can be used as diagnostic and/or prognostic biomarkers, their impact as novel targets for subtype-specific therapy is also possible and suggest important implications for subtype-specific miRNAs.

Bacterial diversity and functional analysis of severe early childhood caries and recurrence in India.

Dental caries is the most prevalent oral disease affecting nearly 70% of children in India and elsewhere. Micro-ecological niche based acidification due to dysbiosis in oral microbiome are crucial for caries onset and progression. Here we report the tooth bacteriome diversity compared in Indian children with caries free (CF), severe early childhood caries (SC) and recurrent caries (RC). High quality V3-V4 amplicon sequencing revealed that SC exhibited high bacterial diversity with unique combination and interrelationship. Gracillibacteria_GN02 and TM7 were unique in CF and SC respectively, while Bacteroidetes, Fusobacteria were significantly high in RC. Interestingly, we found Streptococcus oralis subsp. tigurinus clade 071 in all groups with significant abundance in SC and RC. Positive correlation between low and high abundant bacteria as well as with TCS, PTS and ABC transporters were seen from co-occurrence network analysis. This could lead to persistence of SC niche resulting in RC. Comparative in vitro assessment of biofilm formation showed that the standard culture of S. oralis and its phylogenetically similar clinical isolates showed profound biofilm formation and augmented the growth and enhanced biofilm formation in S. mutans in both dual and multispecies cultures.

Simulated microgravity increases polyploid giant cancer cells and nuclear localization of YAP.

Physical cues are vital in determining cellular fate in cancer. In vitro 3D culture do not replicate forces present in vivo. These forces including tumor interstitial fluid pressure and matrix stiffness behave as switches in differentiation and metastasis, which are intricate features of cancer stem cells (CSCs). Gravity determines the effect of these physical factors on cell fate and functions as evident from microgravity experiments on space and ground simulations. Here, we described the role of simulation of microgravity (SMG) using rotary cell culture system (RCCS) in increasing stemness in human colorectal cancer cell HCT116. We observed distinct features of cancer stem cells including CD133/CD44 dual positive cells and migration in SMG which was not altered by autophagy induction or inhibition. 3D and SMG increased autophagy, but the flux was staggered under SMG. Increased unique giant cancer cells housing complete nuclear localization of YAP were observed in SMG. This study highlights the role of microgravity in regulating stemness in CSC and importance of physical factors in determining the same.

Synthesis and fabrication of novel quinone-based chromenopyrazole antioxidant-laden silk fibroin nanofibers scaffold for tissue engineering applications.

Oxidative stress is critically attributed for impeding tissue repair and regeneration process. Elimination of over-accumulated, deleterious reactive oxygen species (ROS) could be elicited to accelerate healing in tissue engineering applications. Antioxidant biomolecules play a pivotal role in attenuating oxidative stress by neutralizing the free radical effects. Herein, we describe the synthesis and fabrication of novel quinone-based chromenopyrazole (QCP) antioxidant-laden silk fibroin (SF) electrospun nanofiber scaffold (QCP-SF) for tissue engineering applications. The spectral characterization of the synthesized compounds (6a-6h) were analysed by using NMR, FTIR and mass spectra and cell viability study of all the synthesized compounds were evaluated by MTT assay in primary rat bone marrow stem cells (rBMSCs). Among the prepared molecules, compound 6h showed an excellent cell viability, and antioxidant efficacy of compound 6h (QCP) was investigated through 1,1­diphenyl­2­picrylhydiazyl (DPPH) scavenging assay. QCP expressed high antioxidant activity with IC50% of DPPH scavenging was observed about 5.506 ±â€¯0.2786 µg. Novel QCP laden SF fiber scaffolds (QCP-SF) were characterized and incorporation of QCP did not affect the nanofiber architecture of QCP-SF scaffold. QCP-SF scaffold exhibited an enhanced thermal and mechanical stability when compared to native SF fiber mat. In vitro biocompatibility studies were evaluated using NIH 3T3 fibroblasts and rBMSCs. The QCP-SF scaffold displayed an increased cell attachment and proliferation in both cell types. In vitro wound healing study (scratch assay) of QCP-SF scaffold showed an excellent cell migration with NIH 3T3 cells into scratch area and complete cell migration occurred within 24 h. Based on results, we propose that QCP-loaded SF (QCP-SF) nanofibrous scaffolds can serve as a promising potential antioxidant fibrous scaffold for skin tissue engineering applications.

PTEN/FOXO3/AKT pathway regulates cell death and mediates morphogenetic differentiation of Colorectal Cancer Cells under Simulated Microgravity.

Gravity is a major physical factor determining the stress and strain around cells. Both in space experiments and ground simulation, change in gravity impacts the viability and function of various types of cells as well as in vivo conditions. Cancer cells have been shown to die under microgravity. This can be exploited for better understanding of the biology and identification of novel avenues for therapeutic intervention. Here, we described the effect of microgravity simulated using Rotational Cell Culture System-High Aspect Ratio Vessel (RCCS-HARV) on the viability and morphological changes of colorectal cancer cells. We observed DLD1, HCT116 and SW620 cells die through apoptosis under simulated microgravity (SM). Gene expression analysis on DLD1 cells showed upregulation of tumor suppressors PTEN and FOXO3; leading to AKT downregulation and further induction of apoptosis, through upregulation of CDK inhibitors CDKN2B, CDKN2D. SM induced cell clumps had elevated hypoxia and mitochondrial membrane potential that led to adaptive responses like morphogenetic changes, migration and deregulated autophagy, when shifted to normal culture conditions. This can be exploited to understand the three-dimensional (3D) biology of cancer in the aspect of stress response. This study highlights the regulation of cell function and viability under microgravity through PTEN/FOXO3/AKT pathway.