Suppression of Esophageal Cancer Stem-like Cells by SNX-2112 Is Enhanced by STAT3 Silencing

Dual Functionality of [64Cu]Cu-NOTA-San A-Cy7 for Diagnostic Imaging and Surgical Guidance in Hsp90α-Positive Tumors

Intraoperative fluorescence navigation in esophageal cancer enables the clinical translation of fluorescence imaging. Heat shock protein 90 alpha (Hsp90α) plays a vital role in the progression of malignant disease, and elevated Hsp90α expression has been reported in esophageal cancer. The aim of this study was to develop a dual-modality probe, [64Cu]Cu-NOTA-San A-Cy7, for imaging Hsp90α expression in vivo via both positron emission tomography (PET) and fluorescence imaging in esophageal cancer. In this study, the Hsp90α-targeting cyclopeptide Sansalvamide A (San A) was chemically modified with a Cy7 dye and NOTA chelator simultaneously. Experimental assays confirmed that NOTA-San A-Cy7 has a favorable affinity for Hsp90α-positive EC109 cells, with a dissociation constant (Kd) of 1.08 ± 0.19 μM. The probe [64Cu]Cu-NOTA-San A-Cy7 was successfully synthesized with 64CuCl2, achieving a high radiochemical purity of over 95%. Furthermore, the probe demonstrated excellent stability in both saline and serum solutions. The probe was subsequently evaluated in a Hsp90α-positive EC109 tumor-bearing model via PET imaging, which confirmed that Hsp90α-specific uptake was significantly reduced by the co-administration of an excess blocking agent. Biodistribution studies revealed that at 24 hours post-injection, the tumor uptake of the probe was 1.35 ± 0.29%ID/g in the nonblocking group and significantly decreased to 0.73 ± 0.15%ID/g in the blocking group (p < 0.05). Concurrent with the PET experiment, fluorescence imaging was conducted, revealing substantial tumor uptake in the EC109 model. As a proof of concept, imaging-guided surgery utilizing the fluorescent component of this probe was performed. This approach demonstrated the potential for providing surgical guidance in mice positive for Hsp90α, highlighting the dual functionality of the probe for both diagnostic imaging and intraoperative navigation. In summary, our findings unequivocally demonstrate that the dual-modality probe [64Cu]Cu-NOTA-San A-Cy7 holds significant promise as an agent for imaging Hsp90α-positive tumors in vivo, offering a valuable tool for the detection and potential management of such tumors.

Oligonucleotide-Based Therapeutics for STAT3 Targeting in Cancer-Drug Carriers Matter

High expression and phosphorylation of signal transducer and transcription activator 3 (STAT3) are correlated with progression and poor prognosis in various types of cancer. The constitutive activation of STAT3 in cancer affects processes such as cell proliferation, apoptosis, metastasis, angiogenesis, and drug resistance. The importance of STAT3 in cancer makes it a potential therapeutic target. Various methods of directly and indirectly blocking STAT3 activity at different steps of the STAT3 pathway have been investigated. However, the outcome has been limited, mainly by the number of upstream proteins that can reactivate STAT3 or the relatively low specificity of the inhibitors. A new branch of molecules with significant therapeutic potential has emerged thanks to recent developments in the regulatory function of non-coding nucleic acids. Oligonucleotide-based therapeutics can silence target transcripts or edit genes, leading to the modification of gene expression profiles, causing cell death or restoring cell function. Moreover, they can reach untreatable targets, such as transcription factors. This review briefly describes oligonucleotide-based therapeutics that found application to target STAT3 activity in cancer. Additionally, this review comprehensively summarizes how the inhibition of STAT3 activity by nucleic acid-based therapeutics such as siRNA, shRNA, ASO, and ODN-decoy affected the therapy of different types of cancer in preclinical and clinical studies. Moreover, due to some limitations of oligonucleotide-based therapeutics, the importance of carriers that can deliver nucleic acid molecules to affect the STAT3 in cancer cells and cells of the tumor microenvironment (TME) was pointed out. Combining a high specificity of oligonucleotide-based therapeutics toward their targets and functionalized nanoparticles toward cell type can generate very efficient formulations.

Acacetin restrains the malignancy of esophageal squamous carcinoma cells via regulating JAK2/STAT3 pathway

Acacetin is a natural flavonoid compound found in diverse plants, which has strong anti-inflammatory and anti-cancer activities. This work aimed at investigating how acacetin functions on esophageal squamous carcinoma cells. In this work, esophageal squamous carcinoma cell lines were subjected to increasing doses of acacetin, and the proliferative, migrative, invasive and apoptotic phenotypes were evaluated by a series of in vitro experiments. Genes related to acacetin and esophageal cancer were predicted by bioinformatics analysis. The levels of apoptosis-relevant proteins and JAK2/STAT3 pathway-relevant proteins in esophageal squamous carcinoma cells were probed by Western blot. It was revealed that acacetin could block the growth and aggressiveness of TE-1 and TE-10 cells and promote the apoptosis. Acacetin treatment induced bax's expression and repressed bcl-2's expression. Notably, acacetin inhibits JAK2/STAT3 pathway in esophageal squamous carcinoma cells. In summary, acacetin inhibits the malignant progression of esophageal squamous carcinoma via restraining JAK2/STAT3 signaling.

Combinatorial Strategies to Target Molecular and Signaling Pathways to Disarm Cancer Stem Cells

Cancer is an urgent public health issue with a very huge number of cases all over the world expected to increase by 2040. Despite improved diagnosis and therapeutic protocols, it remains the main leading cause of death in the world. Cancer stem cells (CSCs) constitute a tumor subpopulation defined by ability to self-renewal and to generate the heterogeneous and differentiated cell lineages that form the tumor bulk. These cells represent a major concern in cancer treatment due to resistance to conventional protocols of radiotherapy, chemotherapy and molecular targeted therapy. In fact, although partial or complete tumor regression can be achieved in patients, these responses are often followed by cancer relapse due to the expansion of CSCs population. The aberrant activation of developmental and oncogenic signaling pathways plays a relevant role in promoting CSCs therapy resistance. Although several targeted approaches relying on monotherapy have been developed to affect these pathways, they have shown limited efficacy. Therefore, an urgent need to design alternative combinatorial strategies to replace conventional regimens exists. This review summarizes the preclinical studies which provide a proof of concept of therapeutic efficacy of combinatorial approaches targeting the CSCs.