Co-detection of ALDH1A1, ABCG2, ALCAM and CD133 in three A549 subpopulations at the single cell level by one-step digital RT-PCR

Impact of the thyroid hormone T3 and its nuclear receptor TRα1 on colon cancer stem cell phenotypes and response to chemotherapies

Colorectal cancers (CRCs) are highly heterogeneous and show a hierarchical organization, with cancer stem cells (CSCs) responsible for tumor development, maintenance, and drug resistance. Our previous studies showed the importance of thyroid hormone-dependent signaling on intestinal tumor development and progression through action on stem cells. These results have a translational value, given that the thyroid hormone nuclear receptor TRα1 is upregulated in human CRCs, including in the molecular subtypes associated with CSC features. We used an established spheroid model generated from the human colon adenocarcinoma cell line Caco2 to study the effects of T3 and TRα1 on spheroid formation, growth, and response to conventional chemotherapies. Our results show that T3 treatment and/or increased TRα1 expression in spheroids impaired the response to FOLFIRI and conferred a survival advantage. This was achieved by stimulating drug detoxification pathways and increasing ALDH1A1-expressing cells, including CSCs, within spheroids. These results suggest that clinical evaluation of the thyroid axis and assessing TRα1 levels in CRCs could help to select optimal therapeutic regimens for patients with CRC. Proposed mechanism of action of T3/TRα1 in colon cancer spheroids. In the control condition, TRα1 participates in maintaining homeostatic cell conditions. The presence of T3 in the culture medium activates TRα1 action on target genes, including the drug efflux pumps ABCG2 and ABCB1. In the case of chemotherapy FOLFIRI, the increased expression of ABC transcripts and proteins induced by T3 treatment is responsible for the augmented efflux of 5-FU and Irinotecan from the cancer cells. Taken together, these mechanisms contribute to the decreased efficacy of the chemotherapy and allow cells to escape the treatment. Created with BioRender.com .

Biological evaluation of levofloxacin and its thionated derivatives: antioxidant activity, aldehyde dehydrogenase enzyme inhibition, and cytotoxicity on A549 cell line

Levofloxacin (LVX) is among the fluoroquinolones antibiotics that has also been studied in vitro and in vivo for its anticancer effects. In this study, we used LVX and novel LVX thionated derivatives; compounds 2 and 3, to evaluate their antioxidant activity, aldehyde dehydrogenase (ALDH) enzymes activity inhibition, and anticancer activity. Combination treatments with doxorubicin (DOX) were investigated as well. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to determine the antioxidant activity. The NADH fluorescence spectrophotometric activity assay was used to determine the ALDH inhibitory effects. Resazurin dye method was applied for cell viability assays. Molecular Operating Environment software was used for the molecular docking experiments. Compared to ascorbic acid, DPPH assay showed that compound 3 had the highest antioxidant activity among the tested compounds with approximately 35% scavenging activity. On ALDH enzymes, compound 3 showed a significant ALDH activity inhibition compared to compound 2 at 200 µM. The IC50 values for the tested compounds were approximately 100 µM on A549 cell line, a non-small cell lung cancer (NSCLC) cell line. However, significant enhancement of cytotoxicity and reduction of IC50 values were observed by combining DOX and synergism was achieved with LVX with a combination index value of 0.4. The molecular docking test showed a minimum binding energy with a good affinity for compound 3 towards ALDH enzymes. Thionated LVX derivatives, may be repurposed for NSCLC therapy in combination with DOX, taking into account the antioxidant activity, ALDH activity inhibition, and the molecular docking results of compound 3.

Digital PCR for Single-Cell Analysis

Single-cell analysis provides an overwhelming strategy for revealing cellular heterogeneity and new perspectives for understanding the biological function and disease mechanism. Moreover, it promotes the basic and clinical research in many fields at a single-cell resolution. A digital polymerase chain reaction (dPCR) is an absolute quantitative analysis technology with high sensitivity and precision for DNA/RNA or protein. With the development of microfluidic technology, digital PCR has been used to achieve absolute quantification of single-cell gene expression and single-cell proteins. For single-cell specific-gene or -protein detection, digital PCR has shown great advantages. So, this review will introduce the significance and process of single-cell analysis, including single-cell isolation, single-cell lysis, and single-cell detection methods, mainly focusing on the microfluidic single-cell digital PCR technology and its biological application at a single-cell level. The challenges and opportunities for the development of single-cell digital PCR are also discussed.

A critical review: Recent advances in "digital" biomolecule detection with single copy sensitivity

Detection of a single biomolecule, ranging from nucleic acids, proteins, viruses to bacteria, is of paramount importance in various fields including biology, environment, food and agriculture industry, public health, and medicine. With the understanding of the biological functions of these biomolecules (or bioparticles) and their impacts on public health, environmental pollution, and food safety, advanced detection techniques are unprecedentedly demanded for their early and/or sensitive detection. In this critical review, a series of elegant research about digital detection of biomolecules with potential single copy sensitivity is reviewed and summarized with the focus on the design principle and the innovation of how to accomplish the “digital” detection concept. Starting with a brief introduction on the importance of digital detection, recent advances in “digital” biomolecule detection with single copy sensitivity are grouped and discussed based on the difference of signal reporting systems, including surrogate signal development for “digital” detection, direct visualization for “digital” detection, and nucleic acid amplification enabled “digital” detection. Interdisciplinary combination and integration of different cutting-edge techniques are also discussed with details. The review is closed with the conclusion and future trends.

A highly integrated real-time digital PCR device for accurate DNA quantitative analysis

Misclassification of positive partitions in microfluidic digital polymerase chain reaction (dPCR) can cause the false positives and false negatives, which significantly alter the resulting estimate of target DNA molecules. To address this issue, establishing real-time fluorescence interrogation of each partition in microfluidic arrays is an effective way in which false positive and false negative partitions can be eliminated. However, currently available devices for real-time fluorescence interrogation are either not competent for microfluidic digital array, or they are bulky, expensive and entail peripheral equipment due to low integration. Therefore, in this study, a Raspberry Pi based, low-cost and highly integrated device is presented to achieve real-time fluorescence detection for microfluidic digital array, termed real-time dPCR device. In the device, uniform thermocycler, streamlined real-time fluorescence imaging setup, and compact data processing system are all integrated to undergo on-chip dPCR amplification, real-time fluorescence detection, and data analysis. Using this real-time dPCR device, the accuracy of DNA absolute quantification by dPCR is improved, since the misclassification of positive partitions is efficiently reduced based on the characteristic real-time fluorescence curves of positive partitions in a self-priming microfluidic chip. Compared with end-point dPCR on our device and commercialized QuantStudio™ 3D dPCR system, the real-time dPCR on our device exhibits a higher accuracy for DNA quantification. In addition, this real-time dPCR device is much smaller and cheaper than the commercialized Digital PCR system, but not sacrificing the capability of error correction for absolute quantitation analysis. Conclusively, this highly integrated real-time dPCR device is very beneficial for DNA quantitative analysis where the determination accuracy is pivotal.

A new method using machine learning for automated image analysis applied to chip-based digital assays

An automated machine learning based method for image processes applied to digital assays.