Should we keep rocking? Portraits from targeting Rho kinases in cancer

Y-27632 Suppresses the Growth and Migration of Oral Squamous Cell Carcinoma, but Upregulates Autophagy by Suppressing mTOR Effectors

BACKGROUND

The Rho-associated protein kinase (ROCK) inhibitor Y-27632 is a potential immunotherapeutic agent for cancer treatment. Y-27632 blocks the growth and migration of oral squamous cell carcinoma (OSCC) CAL-27 cells. However, detailed studies on the underlying mechanisms have not yet been reported.

METHODS

We investigated the effects of Y-27632 on the proliferation, migration, and invasion of OSCC cells (CAL-27, SCC-4, and SCC-9) using the Cell Counting Kit-8 assay, ethynyl-2'-deoxyuridine staining, cell scratch, and transwell assay in vitro. Next, ROCK1/2 was knocked down using siRNA to confirm that the effects of Y-27632 were mediated by the inhibition of ROCK activity. A xenograft mouse model was used to verify the effects of Y-27632 in vivo. The mechanisms underlying Y-27632-induced tumor suppression were detected using western blotting and qRT-PCR.

RESULTS

Our data demonstrated that Y-27632 potently inhibited OSCC cells (CAL-27, SCC-4, and SCC-9) by inhibiting ROCK activity. In vivo assays confirmed that Y-27632 suppressed OSCC growth by reducing cell proliferation. Biochemical assays demonstrated that Y-27632 inactivated the AKT pathway, and treatment with SC79, an AKT activator, rescued the cell growth and migration inhibition elicited by Y-27632. Further investigation revealed that Y-27632 enhanced autophagy by suppressing the AKT/mTOR pathway.

CONCLUSION

Our study demonstrated that Y-27632 significantly suppressed the growth and migration of OSCC cells and upregulated autophagy via the AKT/mTOR pathway, thus providing a potential therapeutic drug for patients with OSCC.

The role of RhoA-ROCK signaling in benign prostatic hyperplasia: a review

Benign prostatic hyperplasia (BPH) is a common urological disease in middle-aged and elderly men. The main pathological mechanisms of BPH include static factors that increase prostate volume and dynamic factors that increase prostate tension. The RhoA/ROCK signaling pathway is a classical pathway that regulates cell contraction, migration, and growth. In this review, we summarize the potential role of RhoA/ROCK signaling in the development of BPH. The RhoA/ROCK signaling pathway can enhance the contraction of prostate smooth muscle through the Ca2+ sensitization pathway and increase passive tension in the prostate through tissue fibrosis. Additionally, RhoA/ROCK signaling promotes cell proliferation by regulating cell division and may influence apoptosis by affecting the actin cytoskeleton. Furthermore, risk factors, such as inflammation, metabolic syndrome, and hormonal changes, can upregulate RhoA/ROCK signaling, which in turn promotes these risk factors, eventually leading to the development of BPH. Given the role of RhoA/ROCK signaling in regulating multiple pathogenic factors of BPH, this pathway represents a promising molecular target for BPH treatment and warrants further study.

Pioneering first-in-class HDAC-ROCK inhibitors as potential multitarget anticancer agents

AIM

With the aim of simultaneously modulating the epigenetic system and the protein kinase pathway, we selected the enzyme histone deacetylase (HDAC) and the Rho-associated protein kinases (ROCK) as desired targets to develop potential multitarget anticancer agents with additional antimetastatic properties. We report here the rational design, synthesis, and biological evaluation of the first-in-class HDAC/ROCK multitarget inhibitors in pancreatic ductal adenocarcinoma (PDAC) and triple-negative breast cancer (TNBC).

MATERIALS AND METHODS

A molecular docking study performed with the Gold software was used to develop HDAC/ROCK multitarget inhibitors. IC50 values were determined by enzyme assays. The cytotoxicity, anti-migratory and anti-invasive properties of the inhibitors were evaluated using triple-negative breast cancer cells (MDA-MB-231 and HCC 1973) and pancreatic ductal adenocarcinoma cells (Panc-1 and MiaPaCa-2).

RESULTS

C-9 showed significant inhibition of HDAC6, ROCK1 and ROCK2. At the same time, this compound showed strong antiproliferative effects on MDA-MB-231, MiaPaCa-2 and Panc-1 cell lines with IC50 values of 5.81 μM, 3.87 μM and 19.57 μM. In addition, it demonstrated great anti-invasive and anti-migratory effects.

CONCLUSION

The findings of this study strongly suggest that the simultaneous inhibition of ROCK and HDACs holds significant potential as a promising therapeutic strategy in the advancement of cancer treatment.

Discovery of the First-in-Class Dual-Target ROCK/HDAC Inhibitor with Potent Antitumor Efficacy in Vivo That Trigger Antitumor Immunity

Triple-negative breast cancer (TNBC) represents a highly aggressive and heterogeneous malignancy. Currently, multitarget drug approaches present a promising therapeutic approach for TNBC. Utilizing a combinatorial chemistry strategy to construct a virtual screening database, dual ROCK/HDAC-targeting benzothiophene compounds were identified. Notably, compound 10h effectively inhibits ROCK1/2 and HDAC1/2/3/6/8 while demonstrating potent antiproliferative activity against breast cancer cells. In an orthotopic mouse model of breast cancer, 10h significantly suppressed tumor growth without apparent toxicity. Importantly, 10h induced immunogenic cell death (ICD), promoted dendritic cells (DCs) maturation, and activated T cells, thereby initiating antitumor immunity. In conclusion, compound 10h is a novel dual-target ROCK/HDAC inhibitor that represents a promising treatment strategy for TNBC.

Targeting ROCK2 improves macromolecular permeability in a 3D fibrotic pancreatic cancer microenvironment model

Pancreatic cancer is characterized by a densely fibrotic stroma. The fibrotic stroma hinders the intratumoral penetration of nanomedicine and diminishes therapeutic efficacy. Fibrosis is characterized by an abnormal organization of extracellular matrix (ECM) components, namely the abnormal deposition and/or orientation of collagen and fibronectin. Abnormal ECM organization is chiefly driven by pathological signaling in pancreatic stellate cells (PSCs), the main cell type involved in fibrogenesis. However, whether targeting signaling pathways involved in abnormal ECM organization improves the intratumoral penetration of nanomedicines is unknown. Here, we show that targeting transforming growth factor-β (TGFβ)/Rho-associated kinase (ROCK) 1/2 signaling in PSCs normalizes ECM organization and concomitantly improves macromolecular permeability of the fibrotic stroma. Using a 3-dimensional cell culture model of the fibrotic pancreatic cancer microenvironment, we found that pharmacological inhibition of TGFβ or ROCK1/2 improves the permeation of various macromolecules. By using an isoform-specific pharmacological inhibitor and siRNAs, we show that targeting ROCK2, but not ROCK1, alone is sufficient to normalize ECM organization and improve macromolecular permeability. Moreover, we found that ROCK2 inhibition/knockdown attenuates Yes-associated protein (YAP) nuclear localization in fibroblasts co-cultured with pancreatic cancer cells in 3D. Finally, pharmacological inhibition or siRNA-mediated knockdown of YAP normalized ECM organization and improved macromolecular permeability. Our results together suggest that the TGFβ/ROCK2/YAP signaling axis may be therapeutically targeted to normalize ECM organization and improve macromolecular permeability to augment therapeutic efficacy of nanomedicines in pancreatic cancer.

Design, Synthesis, and Biological Evaluation of an Orally Bioavailable, Potent, and Selective ROCK2 Inhibitor for Psoriasis Treatment

Psoriasis, a prevalent chronic skin disorder, remains a significant therapeutic obstacle. This study centers on rho-associated coiled-coil-containing kinase2 (ROCK2) as an advantageous target for treating psoriasis and identifies five potent and selective ROCK2 inhibitors (A31-35). Notably, A32-35 outperform KD025 in ROCK2/ROCK1 selectivity by up to 216-fold. Among these candidates, A31 emerged as an exceedingly promising molecule, showcasing remarkable inhibitory potency (IC50 = 3.7 ± 0.8 nM), 19-fold ROCK2/ROCK1 selectivity, and favorable pharmacokinetics. Insights from the binding mode study further underscored the pivotal role of interactions with Phe103 on the P-loop in determining the selectivity between ROCK1 and ROCK2. In an imiquimod-induced psoriasis-like mouse model, oral administration of A31 notably ameliorated symptoms by targeting the IL-23/Th17 axis. Based on these compelling findings, A31 was selected as a highly promising compound for further investigation as a potential treatment for psoriasis.

ROCK Inhibitors as an Alternative Therapy for Corneal Grafting: A Systematic Review

Currently, corneal blindness is affecting >10 million individuals worldwide, and there is a significant unmet medical need because only 1.5% of transplantation needs are met globally due to a lack of high-quality grafts. In light of this global health disaster, researchers are developing corneal substitutes that can resemble the human cornea in vivo and replace human donor tissue. Thus, this review examines ROCK (Rho-associated coiled-coil containing protein kinases) inhibitors as a potential corneal wound-healing (CWH) therapy by reviewing the existing clinical and nonclinical findings. The systematic review was done from PubMed, Scopus, Web of Science, and Google Scholar for CWH, corneal injury, corneal endothelial wound healing, ROCK inhibitors, Fasudil, Netarsudil, Ripasudil, Y-27632, clinical trial, clinical study, case series, case reports, preclinical study, in vivo, and in vitro studies. After removing duplicates, all downloaded articles were examined. The literature search included the data till January 2023. This review summarized the results of ROCK inhibitors in clinical and preclinical trials. In a clinical trial, various ROCK inhibitors improved CWH in individuals with open-angle glaucoma, cataract, iris cyst, ocular hypertension, and other ocular diseases. ROCK inhibitors also improved ocular wound healing by increasing cell adhesion, migration, and proliferation in vitro and in vivo. ROCK inhibitors have antifibrotic, antiangiogenic, anti-inflammatory, and antiapoptotic characteristics in CWH, according to the existing research. ROCK inhibitors were effective topical treatments for corneal infections. Ripasudil, Y-27632, H-1152, Y-39983, and AMA0526 are a few new ROCK inhibitors that may help CWH and replace human donor tissue.

Drugging Hijacked Kinase Pathways in Pediatric Oncology: Opportunities and Current Scenario

Childhood cancer is considered rare, corresponding to ~3% of all malignant neoplasms in the human population. The World Health Organization (WHO) reports a universal occurrence of more than 15 cases per 100,000 inhabitants around the globe, and despite improvements in diagnosis, treatment and supportive care, one child dies of cancer every 3 min. Consequently, more efficient, selective and affordable therapeutics are still needed in order to improve outcomes and avoid long-term sequelae. Alterations in kinases' functionality is a trademark of cancer and the concept of exploiting them as drug targets has burgeoned in academia and in the pharmaceutical industry of the 21st century. Consequently, an increasing plethora of inhibitors has emerged. In the present study, the expression patterns of a selected group of kinases (including tyrosine receptors, members of the PI3K/AKT/mTOR and MAPK pathways, coordinators of cell cycle progression, and chromosome segregation) and their correlation with clinical outcomes in pediatric solid tumors were accessed through the R2: Genomics Analysis and Visualization Platform and by a thorough search of published literature. To further illustrate the importance of kinase dysregulation in the pathophysiology of pediatric cancer, we analyzed the vulnerability of different cancer cell lines against their inhibition through the Cancer Dependency Map portal, and performed a search for kinase-targeted compounds with approval and clinical applicability through the CanSAR knowledgebase. Finally, we provide a detailed literature review of a considerable set of small molecules that mitigate kinase activity under experimental testing and clinical trials for the treatment of pediatric tumors, while discuss critical challenges that must be overcome before translation into clinical options, including the absence of compounds designed specifically for childhood tumors which often show differential mutational burdens, intrinsic and acquired resistance, lack of selectivity and adverse effects on a growing organism.

Dasabuvir suppresses esophageal squamous cell carcinoma growth in vitro and in vivo through targeting ROCK1

Esophageal squamous cell carcinoma (ESCC) is an upper gastrointestinal cancer with high morbidity and mortality. New strategies are urgently needed to prolong patients' survival. Through screening FDA-approved drugs, we found dasabuvir, a drug approved for hepatitis C virus (HCV) treatment, suppressed ESCC proliferation. Dasabuvir could inhibit the growth of ESCC cells in a time and dose-dependent manner and arrested cell cycle at the G0/G1 phase. The antitumor activity was further validated in vivo using patient-derived xenograft tumor models. In terms of mechanism, we unveil that dasabuvir is a Rho-associated protein kinase 1 (ROCK1) inhibitor. Dasabuvir can bind to ROCK1 and suppress its kinase activity, thus downregulating the phosphorylation of ERK1/2 by ROCK1 and the expression of cyclin-dependent kinase 4 (CDK4) and cyclin D1. These results provide evidence that dasabuvir suppresses ESCC growth in vivo and in vitro through blocking ROCK1/ERK signaling pathway.

Neferine, a novel ROCK1-targeting inhibitor, blocks EMT process and induces apoptosis in non-small cell lung cancer

The compounds derived from Traditional Chinese Medicines have shown various pharmacological activities with unique advantages, especially in the aspect of antitumor. Neferine (Nef), a natural compound, extracted from green seed embryos of Lotus (Nelumbo nucifera Gaertn.) also exerts antitumor effects on cancers. In this study, the effects and mechanisms of Nef on epithelial-to-mesenchymal transition (EMT) process in non-small cell lung cancer (NSCLC) were evaluated. The results showed that Nef had the antitumor effects in vivo and in vitro. Nef significantly suppressed cell viability and induced apoptosis in NSCLC cells, with elevated reactive oxygen species and reduced BCL2/BAX ratio. Nef was also demonstrated to inhibit the invasion, metastasis and EMT process of NSCLC cells, and attenuate EMT-related changes of E-cadherin, N-cadherin and Vimentin at both transcriptional and translational levels. Moreover, we concluded that the inhibitory effects of Nef on EMT was achieved by targeting Rho-associated protein kinase 1, a protein mediating the process of EMT in various cancers. These results showed that Nef had a significant antitumor effect on NSCLC cells by inducing apoptosis and blocking EMT, providing the therapeutical prospect on NSCLC treatment.

Enumeration and Characterization of Circulating Tumor Cells in Patients with Hepatocellular Carcinoma Undergoing Transarterial Chemoembolization

Circulating tumor cells (CTCs), and particularly circulating cancer stem cells (cCSC), are prognostic biomarkers for different malignancies and may be detected using liquid biopsies. The ex vivo culture of cCSCs would provide valuable information regarding biological aggressiveness and would allow monitoring the adaptive changes acquired by the tumor in real time. In this prospective pilot study, we analyzed the presence of EpCAM⁺ CTCs using the IsoFlux system in the peripheral blood of 37 patients with hepatocellular carcinoma undergoing transarterial chemoembolization (TACE). The average patient age was 63.5 ± 7.9 years and 91.9% of the patients were men. All patients had detectable CTCs at baseline and 20 patients (54.1%) showed CTC aggregates or clusters in their peripheral blood. The increased total tumor diameter (OR: 2.5 (95% CI: 1.3-4.8), p = 0.006) and the absence of clusters of CTCs at baseline (OR: 0.2 (95% CI: 0.0-1.0), p = 0.049) were independent predictors of a diminished response to TACE. Culture of cCSC was successful in five out of thirty-three patients, mostly using negative enrichment of CD45^- cells, ultra-low adherence, high glucose, and a short period of hypoxia followed by normoxia. In conclusion, the identification of clusters of CTCs before TACE and the implementation of standardized approaches for cCSC culture could aid to predict outcomes and to define the optimal adjuvant therapeutic strategy for a true personalized medicine in hepatocellular carcinoma.

Molecular mechanisms of osteosarcoma metastasis and possible treatment opportunities

In osteosarcoma patients, metastasis of the primary cancer is the leading cause of death. At present, management options to prevent metastasis are limited and non-curative. In this study, we review the current state of knowledge on the molecular mechanisms of metastasis and discuss promising new therapies to combat osteosarcoma metastasis. Genomic and epigenomic changes, metabolic reprogramming, transcription factors, dysregulation of physiologic pathways, and alterations to the tumor microenvironment are some of the changes reportedly involved in the regulation of osteosarcoma metastasis. Key factors within the tumor microenvironment include infiltrating lymphocytes, macrophages, cancer-associated fibroblasts, platelets, and extracellular components such as vesicles, proteins, and other secreted molecules. We conclude by discussing potential osteosarcoma-limiting agents and their clinical studies.

Chemical Chaperones to Inhibit Endoplasmic Reticulum Stress: Implications in Diseases

The endoplasmic reticulum (ER) is responsible for structural transformation or folding of de novo proteins for transport to the Golgi. When the folding capacity of the ER is exceeded or excessive accumulation of misfolded proteins occurs, the ER enters a stressed condition (ER stress) and unfolded protein responses (UPR) are triggered in order to rescue cells from the stress. Recovery of ER proceeds toward either survival or cell apoptosis. ER stress is implicated in many pathologies, such as diabetes, cardiovascular diseases, inflammatory diseases, neurodegeneration, and lysosomal storage diseases. As a survival or adaptation mechanism, chaperone molecules are upregulated to manage ER stress. Chemical versions of chaperone have been developed in search of drug candidates for ER stress-related diseases. In this review, synthetic or semi-synthetic chemical chaperones are categorized according to potential therapeutic area and listed along with their chemical structure and activity. Although only a few chemical chaperones have been approved as pharmaceutical drugs, a dramatic increase in literatures over the recent decades indicates enormous amount of efforts paid by many researchers. The efforts warrant clearer understanding of ER stress and the related diseases and consequently will offer a promising drug discovery platform with chaperone activity.

Axonal Regeneration: Underlying Molecular Mechanisms and Potential Therapeutic Targets

Axons in the peripheral nervous system have the ability to repair themselves after damage, whereas axons in the central nervous system are unable to do so. A common and important characteristic of damage to the spinal cord, brain, and peripheral nerves is the disruption of axonal regrowth. Interestingly, intrinsic growth factors play a significant role in the axonal regeneration of injured nerves. Various factors such as proteomic profile, microtubule stability, ribosomal location, and signalling pathways mark a line between the central and peripheral axons' capacity for self-renewal. Unfortunately, glial scar development, myelin-associated inhibitor molecules, lack of neurotrophic factors, and inflammatory reactions are among the factors that restrict axonal regeneration. Molecular pathways such as cAMP, MAPK, JAK/STAT, ATF3/CREB, BMP/SMAD, AKT/mTORC1/p70S6K, PI3K/AKT, GSK-3β/CLASP, BDNF/Trk, Ras/ERK, integrin/FAK, RhoA/ROCK/LIMK, and POSTN/integrin are activated after nerve injury and are considered significant players in axonal regeneration. In addition to the aforementioned pathways, growth factors, microRNAs, and astrocytes are also commendable participants in regeneration. In this review, we discuss the detailed mechanism of each pathway along with key players that can be potentially valuable targets to help achieve quick axonal healing. We also identify the prospective targets that could help close knowledge gaps in the molecular pathways underlying regeneration and shed light on the creation of more powerful strategies to encourage axonal regeneration after nervous system injury.

Preclinical evaluation of the ROCK1 inhibitor, GSK269962A, in acute myeloid leukemia

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy with high mortality that urgently requires new treatments. ROCK1 plays an essential role in regulating growth and survival in AML cells. In this study, we evaluated GSK269962A, a selective ROCK1 inhibitor, in preclinical models of AML. Compared with solid tumors, GSK269962A selectively inhibited cell growth and clonogenicity of AML cells. Furthermore, GSK269962A arrested AML cells in the G2 phase and induced apoptosis by regulating multiple cell cycle- and apoptosis-associated proteins. Strikingly, GSK269962A could eliminate leukemia cells from bone marrow, liver, and spleen in an animal model of AML and significantly prolong mouse survival. Mechanistically, GSK269962A could inhibit the growth of AML by blocking ROCK1/c-Raf/ERK signaling pathway. Notably, a correlation was found between the expression levels of ROCK1 protein and the sensitivity of GSK269962A in AML. These data highlight the potential role of ROCK1 as an attractive target for treating AML, as well as the potential of GSK269962A for use in clinical trials of AML.

miR‑5590‑3p inhibits the proliferation and metastasis of renal cancer cells by targeting ROCK2 to inhibit proliferation, migration and invasion

The present study aimed to clarify the role of microRNA (miR)-5590-3p in the progression of renal cell carcinoma (RCC) and investigate the underlying mechanisms. The expression levels of miR-5590-3p, Rho-associated protein kinase (ROCK)2 and β-catenin in RCC cells were measured by reverse transcription-quantitative PCR and western blot analysis. Following overexpression of miR-5590-3p and ROCK2 by transfection of miR-5590-3p mimics and GV367-ROCK2, respectively, changes in the proliferation, migration and invasion of RCC cells were determined through colony-formation, wound-healing and Transwell assays, respectively. The direct binding interaction between miR-5590-3p and ROCK2, initially predicted using Targetscan, was validated by a dual-luciferase reporter assay. The results indicated that miR-5590-3p was downregulated in RCC. Overexpression of miR-5590-3p led to downregulation of ROCK2 and β-catenin and inhibited the proliferation, migration and invasion of RCC cells. The dual-luciferase reporter assay confirmed the binding relationship between miR-5590-3p and ROCK2. Of note, overexpression of ROCK2 effectively reversed the regulatory effects of miR-5590-3p on RCC cells. In conclusion, miR-5590-3p inhibits the proliferation, migration and invasion of RCC cells by targeting ROCK2, which is a potential molecular biomarker and therapeutic target for RCC.

The roles of glycolysis in osteosarcoma

Metabolic reprogramming is of great significance in the progression of various cancers and is critical for cancer progression, diagnosis, and treatment. Cellular metabolic pathways mainly include glycolysis, fat metabolism, glutamine decomposition, and oxidative phosphorylation. In cancer cells, reprogramming metabolic pathways is used to meet the massive energy requirement for tumorigenesis and development. Metabolisms are also altered in malignant osteosarcoma (OS) cells. Among reprogrammed metabolisms, alterations in aerobic glycolysis are key to the massive biosynthesis and energy demands of OS cells to sustain their growth and metastasis. Numerous studies have demonstrated that compared to normal cells, glycolysis in OS cells under aerobic conditions is substantially enhanced to promote malignant behaviors such as proliferation, invasion, metastasis, and drug resistance of OS. Glycolysis in OS is closely related to various oncogenes and tumor suppressor genes, and numerous signaling pathways have been reported to be involved in the regulation of glycolysis. In recent years, a vast number of inhibitors and natural products have been discovered to inhibit OS progression by targeting glycolysis-related proteins. These potential inhibitors and natural products may be ideal candidates for the treatment of osteosarcoma following hundreds of preclinical and clinical trials. In this article, we explore key pathways, glycolysis enzymes, non-coding RNAs, inhibitors, and natural products regulating aerobic glycolysis in OS cells to gain a deeper understanding of the relationship between glycolysis and the progression of OS and discover novel therapeutic approaches targeting glycolytic metabolism in OS.

Rho Kinases in Embryonic Development and Stem Cell Research

The Rho-associated coiled-coil containing kinases (ROCKs or Rho kinases) belong to the AGC (PKA/PKG/PKC) family of serine/threonine kinases and are major downstream effectors of small GTPase RhoA, a key regulator of actin-cytoskeleton reorganization. The ROCK family contains two members, ROCK1 and ROCK2, which share 65% overall identity and 92% identity in kinase domain. ROCK1 and ROCK2 were assumed to be functionally redundant, based largely on their major common activators, their high degree kinase domain homology, and study results from overexpression with kinase constructs or chemical inhibitors. ROCK signaling research has expanded to all areas of biology and medicine since its discovery in 1996. The rapid advance is befitting ROCK’s versatile functions in modulating various cell behavior, such as contraction, adhesion, migration, proliferation, polarity, cytokinesis, and differentiation. The rapid advance is noticeably driven by an extensive linking with clinical medicine, including cardiovascular abnormalities, aberrant immune responsive, and cancer development and metastasis. The rapid advance during the past decade is further powered by novel biotechnologies including CRISPR-Cas and single cell omics. Current consensus, derived mainly from gene targeting and RNA interference approaches, is that the two ROCK isoforms have overlapping and distinct cellular, physiological and pathophysiology roles. In this review, we present an overview of the milestone discoveries in ROCK research. We then focus on the current understanding of ROCK signaling in embryonic development, current research status using knockout and knockin mouse models, and stem cell research.

Circulating Tumor Cells in Hepatocellular Carcinoma: A Comprehensive Review and Critical Appraisal

Hepatocellular carcinoma (HCC) is the fifth most common neoplasm and a major cause of cancer-related death worldwide. There is no ideal biomarker allowing early diagnosis of HCC and tumor surveillance in patients receiving therapy. Liquid biopsy, and particularly circulating tumor cells (CTCs), have emerged as a useful tool for diagnosis and monitoring therapeutic responses in different tumors. In the present manuscript, we evaluate the current evidence supporting the quantitative and qualitative assessment of CTCs as potential biomarkers of HCC, as well as technical aspects related to isolation, identification, and classification of CTCs. Although the dynamic assessment of CTCs in patients with HCC may aid the decision-making process, there are still many uncertainties and technical caveats to be solved before this methodology has a true impact on clinical practice guidelines. More studies are needed to identify the optimal combination of surface markers, to increase the efficiency of ex-vivo expansion of CTCs, or even to target CTCs as a potential therapeutic strategy to prevent HCC recurrence after surgery or to hamper tumor progression and extrahepatic spreading.