[18F]TFB PET/CT misses intense [124I]iodine-avid metastases after redifferentiation therapy in metastatic thyroid cancer.

BACKGROUND: Fluorine 18-labelled tetrafluoroborate ([18F]TFB) is a substrate for the sodium/iodide symporter. In thyroid cancer, [18F]TFB-PET/CT may be an alternative to iodine imaging to evaluate the extent of disease, eligibility for radioiodine treatment, and success of redifferentiation therapies. We report the results of a pilot study to determine tumor uptake of [18F]TFB and compare its properties to [124I]IodinePET/CT in patients with metastatic thyroid cancer. METHODS: Five patients were included in a prospective study. All patients received PET/CT 1 h after injection of 356 ± 12 MBq [18F]TFB and were given 230 ± 9 MBq [124I]Iodine orally on the same day, followed by PET/CT after 48 h. Before redifferentiation therapy, patients underwent an additional baseline [124I]Iodine PET/CT. Cases were analyzed by two board-certified specialists. Detection rates and Spearman correlation for [18F]TFB and [124I]Iodine were calculated. RESULTS: Three patients had poorly differentiated thyroid cancer and received trametinib in a redifferentiation trial. Two patients had papillary thyroid cancer and did not receive redifferentiation therapy. Of the 33 lesions seen before/without redifferentiation therapy, 19 (58%) were visible on [18F]TFB and 30 (91%) on [124I]Iodine imaging. In the patients who underwent redifferentiation therapy, 48 lesions were newly seen on [124I]Iodine PET/CT with a median SUVmax of 3.3 (range, 0.4-285.0). All of these lesions were [18F]TFB-negative. CONCLUSION: [18F]TFB failed to predict radioactive iodine uptake in patients with poorly differentiated thyroid cancer who underwent redifferentiation therapy with trametinib. It is unclear whether such discrepancies may also occur in other redifferentiation therapies or may even be encountered in redifferentiation-naïve thyroid cancer. TRIAL REGISTRATION NUMBER: NCT03196518, registered on June 22, 2017.

An update on redifferentiation strategies for radioactive iodine-refractory differentiated thyroid carcinoma.

PURPOSE: Although most patients with differentiated thyroid carcinoma (DTC) have an excellent prognosis, a subset will experience radioactive iodine refractory (RAI-R) disease, associated with recurrence, distant metastases and worse prognosis. In recent years, redifferentiation has emerged as an attractive approach for patients with RAI-R DTC, a strategy to induce iodine uptake in RAI-R DTC tumor cells and ultimately prolong time to initiation of systemic therapy. METHODS: An overview and critical appraisal of the existing literature on redifferentiation will be presented in this review under the lens of the genotype-specific targeted therapy administered with redifferentiation intent. RESULTS/CONCLUSIONS: Due to the significant heterogeneity across studies, it will be key to harmonize research methodology and support future larger, multicenter prospective trials in order to identify the most suitable candidates for this therapeutic strategy.

Insights into the molecular changes of adipocyte dedifferentiation and its future research opportunities.

Recent studies have challenged the traditional belief that mature fat cells are irreversibly differentiated and revealed they can dedifferentiate into fibroblast-like cells known as dedifferentiated fat (DFAT) cells. Resembling pluripotent stem cells, DFAT cells hold great potential as a cell source for stem cell therapy. However, there is limited understanding of the specific changes that occur following adipocyte dedifferentiation and the detailed regulation of this process. This review explores the epigenetic, genetic, and phenotypic alterations associated with DFAT cell dedifferentiation, identifies potential targets for clinical regulation and discusses the current applications and challenges in the field of DFAT cell research.

Accelerated maturation of ARPE-19 cells for the translational assessment of gene therapy.

The human retinal pigment epithelium (RPE) cell line ARPE-19 is widely used as an alternative to primary RPE despite losing many features of primary RPE. We aimed to determine whether a combination of RPE-specific laminin (LN) and nicotinamide (NAM) could improve ARPE-19 redifferentiation to resemble mature RPE and improve the assessment of RPE-specific gene therapy strategies. ARPE-19 cells were propagated on tissue culture plastic supplemented with NAM and human recombinant LN521-coating. RPE maturation was performed by immunocytochemistry and gene expression by qPCR. Viral transduction experiments with adeno-associated virus (AAV)1 or AAV2, carrying a VMD2-driven GFP, were assessed at 2- and 4-weeks post-plating in the different culturing conditions with a low multiplicity of infection. The combination of LN521 coating with NAM supplementation promoted cytoskeletal and tight junction protein reorganization. The expression of maturation markers bestrophin-1 and RPE 65 was promoted concomitantly with a reduction of several epithelial-mesenchymal transition markers, such as TNF-α, TGF-ß, CDH2, and vimentin. Redifferentiated ARPE-19 transduced at low multiplicity of infection of both AAV1- and AAV2-VMD2-GFP. Expression of GFP was detected at 2 weeks and increased at 4 weeks post-plating. AAV1 exhibited a greater expression efficacy compared to AAV2 in maturated ARPE-19 cells already after 2 weeks with increased efficiency after 4 weeks. Our study demonstrates an improved maturation protocol for ARPE-19 cells in vitro, mimicking an in vivo phenotype with the expression of signature genes and improved morphology. Viral-mediated RPE-specific gene expression demonstrates that the combination cultures mimic in vivo AAV tropism essential to test new gene therapies for RPE-centered diseases.

Characterization of PEBP-like Genes and Function of Capebp1 and Capebp5 in Fruiting Body Regeneration in Cyclocybe aegerita.

Phosphatidylethanolamine-binding proteins (PEBPs) play a crucial role in the growth and development of various organisms. Due to the low sequence similarity compared to plants, humans, and animals, the study of pebp genes in fungi has not received significant attention. The redifferentiation of fruiting bodies is exceedingly rare in fungal development. Hitherto, only a few studies have identified the Capebp2 gene as being associated with this phenomenon in Cyclocybe aegerita. Thus, exploring the role of pebp genes in fruiting body development is imperative. In the present study, four Capebp genes (Capebp1, Capebp3, Capebp4, and Capebp5) were cloned from the AC0007 strain of C. aegerita based on genome sequencing and gene prediction. The findings indicate that the pebp family, in C. aegerita, comprises a total of five genes. Moreover, the sequence similarity was low across the five CAPEBP protein sequences in C. aegerita, and only a few conserved sequences, such as HRY and RHF, were identical. Expression analyses revealed that, similarly to Capebp2, the four Capebp genes exhibit significantly higher expression levels in the fruiting bodies than in the mycelium. Furthermore, overexpressed and RNA interference Capebp1 or Capebp5 transformants were analyzed. The results demonstrate that overexpression of Capebp1 or Capebp5 could induce the regeneration of the lamella or fruiting body, whereas the knockdown of Capebp1 or Capebp5 could lead to the accelerated aging of fruiting bodies. These findings highlight a significant role of Capebp genes in the generation of C. aegerita fruiting bodies and provide a foundation for further exploration into their involvement in basidiomycete growth and development.

Digoxin treatment does not reinduce radioiodine uptake in radioiodine refractory non-medullary thyroid carcinoma.

Objective: Patients with non-medullary thyroid carcinoma (NMTC) that are refractory to radioactive iodine (RAI) have a poor prognosis. Strategies for restoring the ability to take up iodine, so-called redifferentiation, are promising but not suitable for all patients. Preclinical studies, in human cell lines just as in a murine model, have shown that the cardiac glycoside digoxin restored RAI uptake. This prospective single-center open-label study aimed to investigate whether treatment with digoxin could reinduce clinically relevant RAI uptake in patients with metastasized RAI-refractory NMTC. Methods: Eight patients with metastasized RAI-refractory NMTC were included between November 2022 and June 2023. Before treatment, a baseline [123I]NaI scintigraphy was performed. Thereafter, patients were treated with digoxin for 3 weeks. Starting doses depended on age and weight. For safety reasons, the usual therapeutic range was aimed for. After 1 week, the digoxin plasma concentration was measured, and the digoxin dose was adjusted if necessary. After 3 weeks of digoxin treatment, a second [123I]NaI scintigraphy was performed. RAI uptake was compared between the two scintigraphies. Results: Seven patients completed the digoxin treatment and were evaluable. None of the seven patients showed clinically relevant RAI uptake after digoxin treatment. No digoxin-related serious adverse events occurred during this trial. Conclusion: Contrary to results from preclinical trials, in this trial, 3 weeks of digoxin treatment did not reinduce RAI uptake in patients with NMTC. This highlights essential challenges regarding the approach toward optimization of studies aimed to restore the RAI uptake and its therapeutic efficacy through drug repurposing.

Molecular Perspectives in Radioactive Iodine Theranostics: Current Redifferentiation Protocols for Mis-Differentiated Thyroid Cancer.

Thyroid cancer molecular oncogenesis involves functional dedifferentiation. The initiating genomic alterations primarily affect the MAPK pathway signal transduction and generate an enhanced ERK output, which in turn results in suppression of the expression of transcription of the molecules of iodine metabolomics. The clinical end result of these molecular alterations is an attenuation in theranostic power of radioactive iodine (RAI). The utilization of RAI in systemic therapy of metastatic disease requires restoration of the functional differentiation. This concept has been accomplished by modulation of MAPK signaling. Objective responses have been demonstrated in metastatic disease settings. RAI-refractoriness in "differentiated thyroid cancers" remains a clinical problem despite optimized RAI administration protocols. Functional mis-differentiation and associated RAI-indifference are the underlying primary obstacles. MAPK pathway modulation offers a potential for reversal of RAI-indifference and combat refractoriness. This review presents the latest clinical experience and protocols for the redifferentiation of radioiodine-refractory mis-differentiated thyroid cancer, providing a comprehensive overview of the current protocols and intervention strategies used by leading institutions. Timing and techniques of imaging, thyrotropin (TSH) stimulation methods, and redifferentiation agents are presented. The efficacy and limitations of various approaches are discussed, providing an overview of the advantages and disadvantages associated with each of the protocols.

[Thyroid carcinomas: the role of systemic therapies in internal medicine]. / Schilddrüsenkarzinome ­ Rolle internistischer Systemtherapien.

The molecular pathogenesis of thyroid carcinoma is well studied and of importance for the treatment of advanced stages. Differentiated, poorly differentiated and anaplastic carcinomas originate in the follicular cells, while medullary carcinomas derive from the C­cells. The prognosis of differentiated thyroid carcinoma is generally very favourable after surgery and radioiodine therapy. Where tumours progress and lose the ability to enrich iodine, curative treatment is usually not possible. A strategy of watchful waiting is often appropriate. Activating mutations in BRAF or gene fusions of RET and NTRK provide opportunities for targeted therapies. These may be applied with the aim of restoring iodine uptake (redifferentiation). In the absence of molecular therapy targets, multityrosine kinase inhibitors (MKI) are the therapy of choice. If anaplastic thyroid carcinoma is suspected, rapid diagnostic workup including molecular pathology is warranted. Surgery where possible and radiochemotherapy are essential components of therapy. In the presence of a BRAF mutation, inhibition of BRAF and MEK is effective, even if it is not approved in Germany. Where molecular targets are lacking, combination therapy with the MKI lenvatinib and immune checkpoint inhibition is highly effective. Mutations in RET are present in the vast majority of cases of medullary thyroid carcinoma. In aggressive advanced disease, selective RET inhibition has recently been approved as first-line therapy and often leads to an objective response and long-lasting disease stabilisation. In summary, thyroid carcinomas are among the tumour entities for which molecularly targeted therapies can be used most frequently. The involvement of specialised centres is advisable.

Theranostic Risk Stratification for Thyroid Cancer in the Genomic Paradigm.

Theranostics define diagnostic evaluations directing patient-specific therapeutic decisions. Molecular theranostics involves genomic, transcriptomic, proteomic, metabolomic and finally phenonic definitions thyroid cancer differentiation. It is the functional differentiation that determines the sensitivity and accuracy of RAI imaging as well as the effectiveness of RAI treatment. Total thyroidectomy is performed to empower an anticipated RAI treatment. A preoperative determination of the genomic and transcriptomic profile of the tumor is a strong predictor of response to therapeutic interventions. This article discusses the oncopathophysiologic basis of the theranostic risk stratification approach.

Redifferentiation of genetically modified dedifferentiated chondrocytes in a microcavitary hydrogel.

OBJECTIVES: We genetically modified dedifferentiated chondrocytes (DCs) using lentiviral vectors and adenoviral vectors encoding TGF-ß3 (referred to as transgenic groups below) and encapsulated these DCs in the microcavitary hydrogel and investigated the combinational effect on redifferentiation of the genetically manipulated DCs. RESULTS: The Cell Counting Kit-8 data indicated that both transgenic groups exhibited significantly higher cell viability in the first week but inferior cell viability in the subsequent timepoints compared with those of the control group. Real-time polymerase chain reaction and western blot analysis results demonstrated that both transgenic groups had a better effect on redifferentiation to some extent, as evidenced by higher expression levels of chondrogenic genes, suggesting the validity of combination with transgenic DCs and the microcavitary hydrogel on redifferentiation. Although transgenic DCs with adenoviral vectors presented a superior extent of redifferentiation, they also expressed greater levels of the hypertrophic gene type X collagen. It is still worth further exploring how to deliver TGF-ß3 more efficiently and optimizing the appropriate parameters, including concentration and duration. CONCLUSIONS: The results demonstrated the better redifferentiation effect of DCs with the combinational use of transgenic TGF-ß3 and a microcavitary alginate hydrogel and implied that DCs would be alternative seed cells for cartilage tissue engineering due to their easily achieved sufficient cell amounts through multiple passages and great potential to redifferentiate to produce cartilaginous extracellular matrix.

Leveraging molecular targeted drugs and immune checkpoint inhibitors treat advanced thyroid carcinoma to achieve thyroid carcinoma redifferentiation.

Thyroid cancer can be classified into three different types based on the degree of differentiation: well-differentiated, poorly differentiated, and anaplastic thyroid carcinoma. Well-differentiated thyroid cancer refers to cancer cells that closely resemble normal thyroid cells, while poorly differentiated and anaplastic thyroid carcinoma are characterized by cells that have lost their resemblance to normal thyroid cells. Advanced thyroid carcinoma, regardless of its degree of differentiation, is known to have a higher likelihood of disease progression and is generally associated with a poor prognosis. However, the process through which well-differentiated thyroid carcinoma transforms into anaplastic thyroid carcinoma, also known as "dedifferentiation", has been a subject of intensive research. In recent years, there have been significant breakthroughs in the treatment of refractory advanced thyroid cancer. Clinical studies have been conducted to evaluate the efficacy and safety of molecular targeted drugs and immune checkpoint inhibitors in the treatment of dedifferentiated thyroid cancer. These drugs work by targeting specific molecules or proteins in cancer cells to inhibit their growth or by enhancing the body's immune response against the cancer cells. This article aims to explore some of the possible mechanisms behind the dedifferentiation process in well-differentiated thyroid carcinoma. It also discusses the clinical effects of molecular targeted drugs and immune checkpoint inhibitors in thyroid cancer patients with different degrees of differentiation. Furthermore, it offers insights into the future trends in the treatment of advanced thyroid cancer, highlighting the potential for improved outcomes and better patient care.

Ligand Composition and Coating Density Co-Modulate the Chondrocyte Function on Poly(glycerol-dodecanedioate).

Inducing chondrocyte redifferentiation and promoting cartilaginous matrix accumulation are key challenges in the application of biomaterials in articular cartilage repair. Poly(glycerol-dodecanedioate) (PGD) is a viable candidate for scaffold design in cartilage tissue engineering (CTE). However, the surface properties of PGD are not ideal for cell attachment and growth due to its relative hydrophobicity compared with natural extracellular matrix (ECM). In this study, PGD was coated with various masses of collagen type I or hyaluronic acid, individually or in combination, to generate a cell-material interface with biological cues. The effects of ligand composition and density on the PGD surface properties and shape, metabolic activity, cell phenotype, and ECM production of human articular chondrocytes (hACs) were evaluated. Introducing ECM ligands on PGD significantly improved its hydrophilicity and promoted the chondrocyte's anabolic activity. The morphology and anabolic activity of hACs on PGD were co-modulated by ligand composition and density, suggesting a combinatorial effect of both coating parameters on chondrocyte function during monolayer culture. Hyaluronic acid and its combination with collagen maintained a round cell shape and redifferentiated phenotype. This study demonstrated the complex mechanism of ligand-guided interactions between cell and biomaterial substrate and the potential of PGD as a scaffold material in the field of CTE.

Pharmacokinetics/Pharmacodynamics of Dabrafenib and Trametinib for Redifferentiation and Treatment of Radioactive Iodine-Resistant Mutated Advanced Differentiated Thyroid Cancer.

Background: BRAF and MEK inhibitors are cornerstones of the redifferentiation strategy in metastatic radioactive iodine (RAI)-resistant mutant thyroid cancers. We explored the exposure-toxicity relationship for dose-limiting toxicity (DLT) onset in patients treated with dabrafenib and/or trametinib and investigated whether plasma exposure was associated with RAI reuptake. Methods: We conducted a retrospective monocentric study in which we reviewed the electronic medical records of patients treated in our institution with a tumor redifferentiation strategy, for whom plasma concentration of dabrafenib, its active metabolite hydroxy-dabrafenib, and trametinib was measured. Trough concentrations (Cminpred) and total plasma drug exposure (area under the curve, AUC) of dabrafenib (AUCDAB), hydroxy-dabrafenib (AUCOHD), and trametinib (AUCTRA) were estimated. Results: Of the 22 patients treated in a redifferentiation strategy between March 2014 and December 2021, 15 were included in this study. A dabrafenib- or trametinib-related DLT was experienced by 8 (62%) and 9 (64%) patients, respectively. Patients who experienced a trametinib-related DLT exhibited a significantly higher last AUCTRA than the average AUCTRA of patients who had no DLT (390, IQR: 67 vs. 215, IQR: 91 ng/mL·h-1, respectively; p = 0.008). Patients who experienced a dabrafenib-related DLT had a higher AUCDAB than observed in other patients (9265 ng/mL·h-1 vs. 6953 ng/mL·h-1, respectively; p = 0.09). No clinical and demographical characteristic was associated with the DLT onset. Overall, 9 of 15 (60%) patients demonstrated tumor redifferentiation. Patients in whom RAI reuptake was achieved had significant lower AUCDAB (6990 ng/mL·h-1 vs. 9764 ng/mL·h-1, p = 0.014; respectively) compared with patients who did not. Moreover, the relative exposure ratio of AUCOHD/DAB was significantly higher in patients who achieved RAI reuptake (1.11 vs. 0.71, respectively; p = 0.0047). Conclusions: Our data suggest a relationship between DLT onset and trametinib plasma exposure, as well as an association between achievement of RAI reuptake and dabrafenib plasma exposure (AUC and ratio of AUCOHD/DAB). These data imply that the use of plasma drug monitoring could be helpful in guiding clinical practice in redifferentiation treatment.

Dedifferentiated fat cells: current applications and future directions in regenerative medicine.

Stem cell therapy is the most promising treatment option for regenerative medicine. Therapeutic effect of different stem cells has been verified in various disease model. Dedifferentiated fat (DFAT) cells, derived from mature adipocytes, are induced pluripotent stem cells. Compared with ASCs and other stem cells, the DFAT cells have unique advantageous characteristics in their abundant sources, high homogeneity, easily harvest and low immunogenicity. The DFAT cells have shown great potential in tissue engineering and regenerative medicine for the treatment of clinical problems such as cardiac and kidney diseases, autoimmune disease, soft and hard tissue defect. In this review, we summarize the current understanding of DFAT cell properties and focus on the relevant practical applications of DFAT cells in cell therapy in recent years.

Overexpression of the Capebp2 Gene Encoding the PEBP-like Protein Promotes the Cap Redifferentiation in Cyclocybe aegerita.

Phosphatidylethanolamine-binding protein (PEBP) is widely involved in various physiological behaviors, such as the transition from vegetative growth to reproductive growth in plants, tumorigenesis in the human, etc. However, few functional studies have examined pebp genes affecting the development of fungi. In this study, Capebp2 was cloned from Cyclocybe aegerita AC0007 strains based on the genome sequence and gene prediction, and the sequence alignment of CaPEBP2 with other PEBP proteins from other biological sources including plant, animal, fungi, and bacteria indicated that PEBP had low sequence similarity in fungi, whereas all protein sequences had some conserved motifs such as DPDAP and HRY. Expression analysis showed the transcription level of Capebp2 increased approximately 20-fold in fruiting bodies compared with mycelia. To uncover the function of Capebp2 in C. aegetita development, Capebp2 was cloned into a pATH vector driven by the actin promoter for obtaining overexpression transformant lines. Fruiting experiments showed the transformed strains overexpressing Capebp2 exhibited redifferentiation of the cap on their surface, including intact fruiting bodies or partial lamella during fruiting development stage, and the longitudinal section indicated that all regenerated bodies or lamella sprouted from the flesh and shared the epidermis with the mother fruiting bodies. In summary, the sequence characterization of Capebp2, expression level during different development stages, and function on fruiting body development were documented in this study, and these findings provided a reference to study the role of pebp in the development process of basidiomycetes. Importantly, gene mining of pebp, function characterization, and the regulating pathways involved need to be uncovered in further studies.

OCT4 induces long-lived dedifferentiated kidney progenitors poised to redifferentiate in 3D kidney spheroids.

Upscaling of kidney epithelial cells is crucial for renal regenerative medicine. Nonetheless, the adult kidney lacks a distinct stem cell hierarchy, limiting the ability to long-term propagate clonal populations of primary cells that retain renal identity. Toward this goal, we tested the paradigm of shifting the balance between differentiation and stemness in the kidney by introducing a single pluripotency factor, OCT4. Here we show that ectopic expression of OCT4 in human adult kidney epithelial cells (hKEpC) induces the cells to dedifferentiate, stably proliferate, and clonally emerge over many generations. Control hKEpC dedifferentiate, assume fibroblastic morphology, and completely lose clonogenic capacity. Analysis of gene expression and histone methylation patterns revealed that OCT4 represses the HNF1B gene module, which is critical for kidney epithelial differentiation, and concomitantly activates stemness-related pathways. OCT4-hKEpC can be long-term expanded in the dedifferentiated state that is primed for renal differentiation. Thus, when expanded OCT4-hKEpC are grown as kidney spheroids (OCT4-kSPH), they reactivate the HNF1B gene signature, redifferentiate, and efficiently generate renal structures in vivo. Hence, changes occurring in the cellular state of hKEpC following OCT4 induction, long-term propagation, and 3D aggregation afford rapid scale-up technology of primary renal tissue-forming cells.

Redifferentiation of Differentiated Thyroid Cancer: Clinical Insights from a Narrative Review of Literature.

Background: Patients who have metastatic differentiated thyroid cancer (mDTC) frequently have negative diagnostic and/or post-therapy radioiodine scans. As a result, 131I therapy is frequently no longer considered a therapeutic option for these patients. However, with the knowledge of genomic alterations of patients with mDTC, the use of selected agents in specific patient groups may be used with the intention to re-establish 131I uptake (i.e., redifferentiation) and additional 131I therapy. The objectives of this narrative review are to present definitions of related terminology, a brief overview of the molecular mechanisms of redifferentiating agents, and a narrative review of the literature for redifferentiation in patients who have radioiodine refractory mDTC. Summary: We searched multiple electronic databases and reviewed the relevant English-language literature reported after 2010. Fourteen articles were included in this narrative review. Conclusions: Preliminary data suggest that select agents may offer potential for re-establishing 131I uptake in selected patients with radioiodine refractory mDTC (e.g., negative diagnostic and/or post-therapy radioiodine scans). These agents may also enhance uptake (e.g., uptake enhancement) in patients who have 131I uptake in mDTC on a diagnostic and/or post-therapy radioiodine scan. As a result, this may facilitate higher absorbed dose delivered (Gy (rad]) per 131I activity administered [GBq (mCi)]. This in turn may increase the likelihood of a better therapeutic effect for the planned administered 131I activity or a reduction in the originally planned administered 131I activity, while achieving the same intended therapeutic effect with potentially less untoward effects. Further studies are warranted to confirm these preliminary observations and to confirm acceptable subsequent 131I therapy responses after redifferentiation and/or uptake enhancement.

Experimental conditions and protein markers for redifferentiation of human coronary artery smooth muscle cells.

A phenotype switch from contractile type to proliferative type of arterial smooth muscle cells is known as dedifferentiation, but to the best of our knowledge, little is known about redifferentiation of coronary artery smooth muscle cells. The purpose of the present study was to determine in vitro culture conditions for inducing redifferentiation of coronary artery smooth muscle cells. In addition, the present study aimed to determine protein markers for detection of redifferentiated arterial smooth muscle cells. Human coronary artery smooth muscle cells (HCASMCs) were cultured in the presence or absence of growth factors, including epidermal growth factor, fibroblast growth factor-B and insulin. Protein expression and migration activity of HCASMCs were evaluated using western blotting and migration assay, respectively. In HCASMCs 5 days after 100% confluency, expression levels of α-smooth muscle actin (α-SMA), calponin, caldesmon and SM22α were significantly increased, while expression levels of proliferation cell nuclear antigen (PCNA) and S100A4 and migration activity were significantly decreased, compared with the corresponding levels just after reaching 100% confluency, indicating that redifferentiation occurred. Redifferentiation was also induced in a low-density culture of HCASMCs in the medium without growth factors. When the culture medium for confluent cells was replaced daily with fresh medium, the expression levels of α-SMA, caldesmon, SM22α, PCNA and S100A4 and migration activity were not significantly different but the calponin expression was significantly increased compared with the levels in dedifferentiated cells just after reaching 100% confluency. Thus, redifferentiation was induced in HCASMCs by deprivation of growth factors from culture medium. The results suggested that α-SMA, caldesmon and SM22α, but not calponin, are markers of redifferentiation of HCASMCs.

MAPK Pathway Inhibitors in Thyroid Cancer: Preclinical and Clinical Data.

Thyroid cancer is the most common endocrine cancer, with a good prognosis in most cases. However, some cancers of follicular origin are metastatic or recurrent and eventually become radioiodine refractory thyroid cancers (RAIR-TC). These more aggressive cancers are a clinical concern for which the therapeutic arsenal remains limited. Molecular biology of these tumors has highlighted a hyper-activation of the Mitogen-Activated Protein Kinases (MAPK) pathway (RAS-RAF-MEK-ERK), mostly secondary to the BRAFV600E hotspot mutation occurring in about 60% of papillary cancers and 45% of anaplastic cancers. Therapies targeting the different protagonists of this signaling pathway have been tested in preclinical and clinical models: first and second generation RAF inhibitors and MEK inhibitors. In clinical practice, dual therapies with a BRAF inhibitor and a MEK inhibitor are being recommended in anaplastic cancers with the BRAFV600E mutation. Concerning RAIR-TC, these inhibitors can be used as anti-proliferative drugs, but their efficacy is inconsistent due to primary or secondary resistance. A specific therapeutic approach in thyroid cancers consists of performing a short-term treatment with these MAPK pathway inhibitors to evaluate their capacity to redifferentiate a refractory tumor, with the aim of retreating the patients by radioactive iodine therapy in case of re-expression of the sodium-iodide symporter (NIS). In this work, we report data from recent preclinical and clinical studies on the efficacy of MAPK pathway inhibitors and their resistance mechanisms. We will also report the different preclinical and clinical studies that have investigated the redifferentiation with these therapies.

Molecular basis and targeted therapies for radioiodine refractory thyroid cancer.

Patients diagnosed with radioiodine refractory thyroid cancer (RAIR-TC) are not amenable to novel 131 I therapy due to the reduced expression of sodium iodide symporter (Na+/I- symporter, NIS) and/or the impairment of NIS trafficking to the plasma membrane. RAIR-TC patients have a relatively poor prognosis with a mean life expectancy of 3-5 years, contributing to the majority of TC-associated mortality. Identifying RAIR-TC patients and selecting proper treatment strategies remain challenging for clinicians. In this review, we demonstrate the updated clinical scenarios or the so-called "definitions" of RAIR-TC suggested by several associations based on 131 I uptake ability and tumor response post-131 I therapy. We also discuss current knowledge of the molecular alterations involved in membrane-localized NIS loss, which provides a preclinical basis for the development of targeted therapies, in particular, tyrosine kinase inhibitors (TKIs), redifferentiation approaches, and immune checkpoint inhibitors.