ABSTRACT
INTRODUCTION: Protoporphyrin-IX (PpIX), a photosensitizer used in photodynamic therapy, has limitations due to its hydrophobicity, rapid photobleaching, and low absorption peak in the red region. These limitations make the use of PpIX less effective for photodynamic therapy treatments. In this study, we harnessed the power of microfluidic technology to manipulate the properties of PpIX and quickly synthesize albumin-based hybrid nanoshells with high reproducibility. METHODS AND MATERIAL: To begin with, we designed a microfluidic chip with SolidWorksâ software; then the chip was fabricated in Poly(methyl methacrylate) (PMMA) material using micromilling and thermal bonding. We synthesized PpIX-loaded CTAB micelles and subsequently transformed the PpIX structure into photo-protoporphyrin (PPP,) by opto-microfluidic chip (Integrating a microfluidic chip with a light source). Simultaneously with CTAB-PPP synthesis complex, we trapped it in binding sites of bovine serum albumin (BSA). Afterward, we used the same method (without irradiating) to generate a hybrid nanostructure consisting of hollow gold nanoshells (HGN) and BSACTAB-PPP. Then, after physical characterization of nanostructures, the photodynamic effects of the agents (HGNs, CTAB-PpIX, BSA-CTABPpIX, HGN-BSA-CTAB-PpIX, CTAB-PPP, BSA-CTAB-PPP, and HGNs-BSA-CTAB-PPP) were evaluated on MDA-MB-231 and 4T1 cells and the cytotoxic properties of the therapeutic agents after treatment for 24, 48, and 72 hours were investigated using MTT assay. Finally, we analyzed the findings using GraphPad Prism 9.0 software. RESULTS: Results revealed that the opto-microfluidic assisted synthesis of HGN-BSA-CTAB-PPP is highly efficient and reproducible, with a size of 120 nm, a zeta potential of -16 mV, and a PDI index of 0.357. Furthermore, the cell survival analysis demonstrated that the HGNBSA-CTAB-PPP hybrid nanostructure can significantly reduce the survival of MDA-MB-231 and 4T1 cancer cells at low radiation doses (<â¯10 J/cm2) when exposed to an incoherent light source due to its strong absorption peak at a wavelength of 670 nm. CONCLUSION: This research indicates that developing albumin-based multidrug hybrid nanostructures using microfluidic technology could be a promising approach to design more efficient photodynamic therapy studies.
Subject(s)
Nanoshells , Photochemotherapy , Triple Negative Breast Neoplasms , Humans , Photochemotherapy/methods , Photosensitizing Agents/therapeutic use , Protoporphyrins/pharmacology , Gold/pharmacology , Triple Negative Breast Neoplasms/drug therapy , Cetrimonium , Microfluidics , Reproducibility of Results , Serum Albumin, Bovine , Cell Line, TumorABSTRACT
There is a growing interest in developing microfluidic biosensors for the accurate and reproducible analysis of various biomarkers obtained from liquid biopsy. This paper reports a novel microfluidic electrochemical aptasensor for determination of A549 cells as integrin α6ß4-containing cell model and circulating tumor cell (CTC) model of NSCLC, based on target-induced structure switching mode. The conformational change of IDA aptamer structure with an affinity towards A549 cells, in the absence and presence of A549 cells allowed selective and sensitive detection of A549 cells. The microfluidic biosensor consisted of a microchip integrated with a screen-printed gold electrode functionalized with SH-IDA aptamers via covalent chemistry. Target solution containing A549 cells in Phosphate-buffered saline could be introduced to the microchip for analysis. Upon exposing to redox probe, a reduction in peak current occurred. Required flow sequencing for various steps of the detection protocol was performed using on-chip gas-actuated microvalves with programmable operation. The microfluidic biosensor provided a wide linear dynamic range of 50-5 × 105 cells/mL and allowed determination of A549 cells with a detection limit of 14 cells/mL. Furthermore, the microfluidic biosensor was efficiently used for detection of A549 cells in complex matrices such as human serum. Our novel microfluidic aptasensor presents an enabling analytical platform to perform various detections of low volume biomarkers with high accuracy and reproducibility.
Subject(s)
Aptamers, Nucleotide , Biosensing Techniques , Humans , Aptamers, Nucleotide/chemistry , Electrochemical Techniques/methods , Microfluidics , Integrin alpha6beta4 , A549 Cells , Reproducibility of Results , Gold/chemistry , Biosensing Techniques/methods , Biomarkers , Limit of DetectionABSTRACT
Microfluidics provides enabling platforms for various cell culture, drug testing and synthesis of drug carriers using chip-based microsystems. In this study, we present a novel integrated whole-thermoplastic microfluidic chip to provide a platform for on-chip cell culture at static and dynamic conditions. The whole chip was made of polymethyl methacrylate (PMMA) and thermoplastic polyurethane (TPU) using high precision micromilling and laser micromachining, assembled by thermal fusion bonding. Prior to fabricate the integrated microchip, a pneumatic solo diffuser-nozzle micropump was fabricated and characterized to evaluate its functionality for on-chip pumping. Then the micropump was integrated with a microbioreactor and an oxygenator in a microchip for flow pumping required for on-chip cell culture. Oxygenator, made of a thin TPU membrane and a reservoir, was implemented in the microchip because of low oxygen permeability of PMMA. To design the oxygenator for sufficient oxygen delivery to the chip, numerical simulation was performed using COMSOL Multiphysics® to evaluate oxygen concentration distribution inside the microchip. Finally, the diffuser-nozzle micropump was integrated with the oxygenator and a bioreactor on the microchip for cell culture with on-chip pumping. Culture of DFW cells was performed on the integrated chip for three days, and cell survival was evaluated with Trypan Blue assay. The findings reveal that the proposed integrated chip with on-chip pumping could be employed for conducting various cell culture studies.
Subject(s)
Microfluidics , Polymethyl Methacrylate , Bioreactors , Cell Culture Techniques , Equipment Design , Oxygen , OxygenatorsABSTRACT
Skin cancer is the leading malignancy in immunosuppressed patients, including organ transplant recipients (OTRs), which is increasing in incidence as OTRs live longer. We performed a single-center case series of 4 patients with scalp pleomorphic dermal sarcoma and a history of multiple keratinocyte carcinomas. Outcomes included incidence of dermal sarcoma, dermal sarcoma-related mortality, and histopathologic findings. Out of more than 200 patients followed over a 3-year period in Massachusetts General Hospital High Risk Skin Cancer Clinics, all skin cancer-related deaths (2/2) were due to metastatic dermal sarcoma. Three of 4 patients diagnosed with scalp dermal sarcoma were OTRs and had been on at least one immunosuppressive medication for a median of 9 years. For patients who died from dermal sarcoma, the median time between diagnosis and death was 6 months. Our findings suggest pleomorphic dermal sarcoma contributes to skin cancer-related morbidity and mortality in OTRs.
Subject(s)
Organ Transplantation , Sarcoma , Skin Neoplasms , Humans , Immunocompromised Host , Organ Transplantation/adverse effects , Sarcoma/complications , Skin Neoplasms/pathology , Transplant RecipientsABSTRACT
Fibrosis is a pathological hallmark of systemic sclerosis, a deadly autoimmune disease affecting the connective tissues of multiple organs. However, the immune mechanisms underlying fibrosis and systemic sclerosis remain unclear. To determine the initiating immune pathway in fibrosis, we investigated the role of type 2 alarmin cytokines in the mouse model of skin fibrosis. Wild-type mice that received subcutaneous bleomycin injections developed skin fibrosis accompanied by elevated IL-33 expression in the dermis. Likewise, we found IL-33 upregulation in human skin fibrosis. Mice with germline deletion of IL-33 receptor (ST2 knockout) showed markedly exacerbated skin fibrosis in association with significantly increased T helper 2 cell to regulatory T-cell ratio in the skin. Mice that lacked ST2 specifically on regulatory T cells (Foxp3Cre,ST2flox/flox) showed significantly worse skin fibrosis, increased T helper 2 to regulatory T cell ratio and IL-13 expression in the skin compared with wild-type mice. Our findings show that IL-33 cytokine signaling to regulatory T cells suppresses skin fibrosis and highlight a potential therapeutic axis to alleviate the debilitating manifestations of systemic sclerosis.
Subject(s)
Interleukin-33 , Scleroderma, Systemic , T-Lymphocytes, Regulatory , Alarmins/metabolism , Animals , Bleomycin , Cytokines/metabolism , Disease Models, Animal , Fibrosis , Forkhead Transcription Factors/metabolism , Humans , Interleukin-1 Receptor-Like 1 Protein/genetics , Interleukin-1 Receptor-Like 1 Protein/metabolism , Interleukin-13/metabolism , Interleukin-33/metabolism , Mice , Skin/pathology , T-Lymphocytes, Regulatory/metabolismABSTRACT
Interleukin (IL)-33 cytokine plays a critical role in allergic diseases and cancer. IL-33 also has a nuclear localization signal. However, the nuclear function of IL-33 and its impact on cancer is unknown. Here, we demonstrate that nuclear IL-33-mediated activation of SMAD signaling pathway in epithelial cells is essential for cancer development in chronic inflammation. Using RNA and ChIP sequencing, we found that nuclear IL-33 repressed the expression of an inhibitory SMAD, Smad6, by interacting with its transcription factor, RUNX2. IL-33 was highly expressed in the skin and pancreatic epithelial cells in chronic inflammation, leading to a markedly repressed Smad6 expression as well as dramatically upregulated p-SMAD2/3 and p-SMAD1/5 in the epithelial cells. Blocking TGF-ß/SMAD signaling attenuated the IL-33-induced cell proliferation in vitro and inhibited IL-33-dependent epidermal hyperplasia and skin cancer development in vivo. IL-33 and SMAD signaling were upregulated in human skin cancer, pancreatitis, and pancreatitis-associated pancreatic cancer. Collectively, our findings reveal that nuclear IL-33/SMAD signaling is a cell-autonomous tumor-promoting axis in chronic inflammation, which can be targeted by small-molecule inhibitors for cancer treatment and prevention.
Subject(s)
Carcinogenesis/metabolism , Interleukin-33/metabolism , Pancreatic Neoplasms/metabolism , Signal Transduction , Skin Neoplasms/metabolism , Smad6 Protein/metabolism , Animals , Cell Line , Cell Line, Tumor , Cell Nucleus/metabolism , Core Binding Factor Alpha 1 Subunit/metabolism , Epithelial Cells/metabolism , Epithelial Cells/pathology , Female , Inflammation , Male , Mice , Mice, Inbred C57BL , Transforming Growth Factor beta/metabolismABSTRACT
Immune checkpoint blockade (ICB) is highly effective for the treatment of metastatic cancers, but its side effects are incompletely understood. The objective of this article is to highlight hypertrophic lichen planus (HLP) with histological features diagnosed as squamous cell carcinoma (SCC), which is a potential cutaneous reaction to ICB. Two patients (75 and 69 years) presented with lesions diagnosed as SCC on biopsy, which developed after 3-9 months on ICB therapy. Biopsies demonstrated endophytic, atypical, or cystic squamous proliferations consistent with cutaneous SCC. However, the clinical presentation including monomorphic nature of the lesions and lichenoid inflammation in the background were consistent with HLP. Patients initially received topical 5-fluorouracil (5-FU) to reduce the hyperkeratotic lesions followed by topical steroids. The eruptions readily responded to this treatment regimen. Dermatologic immune-related adverse events (irAEs) are the most common irAEs associated with ICB therapy. Our findings indicate that HLP resembling SCC on biopsy is a potential side effect of ICB that can be correctly diagnosed on careful clinical exam and is responsive to ICB cessation and topical steroid with or without 5-FU treatment. KEY POINTS: Immune checkpoint blockade is associated with cutaneous immune-related adverse events including lichen planus. Hypertrophic lichen planus can appear as squamous cell carcinoma histologically and clinical context is key for the proper diagnosis. Hypertrophic lichen planus can be safely treated with topical steroids with or without topical 5-fluorouracil in cases with severe hyperkeratotic lesions. Immune checkpoint blockade may be safely continued if clinical presentation is consistent with hypertrophic lichen planus.
Subject(s)
Carcinoma, Squamous Cell , Lichen Planus , Skin Neoplasms , Carcinoma, Squamous Cell/drug therapy , Humans , Immune Checkpoint Inhibitors , Lichen Planus/drug therapy , Skin Neoplasms/drug therapyABSTRACT
Early growth response-1 (EGR1) is a transcription factor correlated with prostate cancer (PC) progression in a variety of contexts. For example, EGR1 levels increase in response to suppressed androgen receptor signaling or loss of the tumor suppressor, PTEN. EGR1 has been shown to regulate genes influencing proliferation, apoptosis, immune cell activation, and matrix degradation, among others. Despite this, the impact of EGR1 on PC metastatic colonization is unclear. We demonstrate using a PC model (DU145/RasB1) of bone and brain metastasis that EGR1 expression regulates angiogenic and osteoclastogenic properties of metastases. We have shown previously that FN14 (TNFRSF12A) and downstream NF-κB signaling is required for metastasis in this model. Here we demonstrate that FN14 ligation also leads to NF-κB-independent, MEK-dependent EGR1 expression. EGR1-depletion in DU145/RasB1 cells reduced both the number and size of metastases but did not affect primary tumor growth. Decreased EGR1 expression led to reduced blood vessel density in brain and bone metastases as well as decreased osteolytic bone lesion area and reduced numbers of osteoclasts at the bone-tumor interface. TWEAK (TNFSF12) induced several EGR1-dependent angiogenic and osteoclastogenic factors (e.g., PDGFA, TGFB1, SPP1, IL6, IL8, and TGFA, among others). Consistent with this, in clinical samples of PC, the level of several genes encoding angiogenic/osteoclastogenic pathway effectors correlated with EGR1 levels. Thus, we show here that EGR1 has a direct effect on prostate cancer metastases. EGR1 regulates angiogenic and osteoclastogenic factors, informing the underlying signaling networks that impact autonomous and microenvironmental mechanisms of cancer metastases.
Subject(s)
Adenocarcinoma/pathology , Early Growth Response Protein 1/physiology , Neovascularization, Pathologic/genetics , Osteogenesis/genetics , Prostatic Neoplasms/pathology , Adenocarcinoma/blood supply , Adenocarcinoma/genetics , Animals , Bone Neoplasms/genetics , Bone Neoplasms/secondary , Early Growth Response Protein 1/genetics , Gene Expression Regulation, Neoplastic , Humans , Male , Mice , Mice, Inbred NOD , Mice, Nude , Mice, SCID , Neoplasm Metastasis , Neovascularization, Pathologic/pathology , PC-3 Cells , Prostatic Neoplasms/blood supply , Prostatic Neoplasms/genetics , RAW 264.7 Cells , Signal Transduction/genetics , Tumor Cells, Cultured , Tumor Microenvironment/geneticsSubject(s)
Autoimmune Diseases , Micafungin/adverse effects , Neutropenia , Aged , Autoimmune Diseases/chemically induced , Autoimmune Diseases/metabolism , Autoimmune Diseases/pathology , Humans , Male , Micafungin/administration & dosage , Neutropenia/chemically induced , Neutropenia/metabolism , Neutropenia/pathologyABSTRACT
Chronic inflammation's tumor-promoting potential is well-recognized; however, the mechanism underlying the development of this immune environment is unknown. Studying the transition from acute, tumor-suppressive to chronic, tumor-promoting allergic contact dermatitis (ACD) revealed how tumor-promoting chronic inflammation develops. Epidermis-derived interleukin (IL)-33 up-regulation and its induction of regulatory T cell (Treg) accumulation in the skin preceded the transition from acute to chronic ACD and triggered the tumor-promoting immune environment in chronic ACD. Mice lacking IL-33 were protected from chronic ACD and its skin cancer sequela compared with wild-type controls (P = 0.0002). IL-33's direct signaling onto Tregs was required for the development of the tumor-promoting immune environment in the skin. IL-33-Treg signaling was also required for chronic colitis and its associated colorectal cancer development in a colitis model (P < 0.0001). Significantly increased IL-33 and Tregs marked the perilesional skin and colon in patients with cancer-prone chronic inflammatory diseases. Our findings elucidate the role of the IL-33/Treg axis in creating a tumor-promoting immune environment in chronic inflammatory diseases and suggest therapeutic targets for cancer prevention and treatment in high-risk patients.
Subject(s)
Colitis/immunology , Colorectal Neoplasms/immunology , Dermatitis, Allergic Contact/immunology , Interleukin-33/immunology , T-Lymphocytes, Regulatory/immunology , Animals , Chronic Disease , Colitis/complications , Colorectal Neoplasms/complications , Dermatitis, Allergic Contact/complications , Humans , Interleukin-1 Receptor-Like 1 Protein/genetics , Interleukin-1 Receptor-Like 1 Protein/metabolism , Mice , Mice, Knockout , Skin Neoplasms/complications , Skin Neoplasms/immunology , Up-RegulationABSTRACT
High-risk skin cancer is a rare, but severe, complication associated with discoid lupus erythematosus (DLE). Chronic scar, inflammation, UVR, and immunosuppressive medications are proposed explanations for this heightened skin cancer risk; however, the exact mechanism driving skin carcinogenesis in DLE is unknown. The distinct co-localization of multiple independent skin cancers with areas of active inflammation in two DLE patients followed over 8 years strongly suggested that lupus inflammation promotes skin carcinogenesis in DLE. To investigate this clinical observation, we subjected lupus-prone MRL/lpr and control (MRL/n) mice to a skin carcinogenesis protocol. Skin tumors developed preferentially within the cutaneous lupus inflammation without scarring in MRL/lpr mice (P < 0.01). The inflammation in MRL/lpr skin was characterized by the accumulation of regulatory T cells, mast cells, M2 macrophages, and markedly elevated transforming growth factor-ß1 and IL-6 levels, which have been linked to tumor promotion. Tacrolimus treatment reduced skin inflammation and blocked cancer development in MRL/lpr mice (P = 0.0195). A similar tumor-promoting immune environment was detected in SCCs and the perilesional skin of cancer-prone DLE patients. Therefore, discoid lupus inflammation promotes skin cancer in high-risk DLE patients, and blocking the inflammation may be critical for preventing this life-threatening complication of DLE.
Subject(s)
Cytokines/metabolism , Inflammation/pathology , Lupus Erythematosus, Discoid/pathology , Skin Neoplasms/etiology , Skin/pathology , Animals , Carcinogenesis , Chronic Disease , Female , Humans , Inflammation/complications , Inflammation/metabolism , Lupus Erythematosus, Discoid/complications , Lupus Erythematosus, Discoid/metabolism , Mice , Mice, Inbred MRL lpr , Middle Aged , Skin Neoplasms/metabolism , Skin Neoplasms/pathologyABSTRACT
Cutaneous reactions are among the most prevalent immune-related adverse events in patients treated with immunotherapy. Given that immunotherapies often act through blocking inhibitory signals on T cells, these treatments also have the potential to generate a host of immune toxicities. We report the case of a 73-year-old woman with a history of non-small cell lung cancer treated with nivolumab 10 months prior to presentation who developed painful nodules, bullae, and a scaly rash on her extremities. Four months after discontinuation of nivolumab, she noted an acute eruption of painful nodules on her extremities, followed by pink papules and tense bullae on her palms and soles. Biopsies were performed of three lesions in sites of varying morphologies. These findings were felt to be consistent with a nivolumab-induced lichenoid reaction. She was initially treated with intralesional steroid injections, topical steroid ointment, and liquid nitrogen cryotherapy with minimal improvement. As the lesions continued to progress, the patient was admitted to the hospital and started on intravenous methylprednisolone. She eventually transitioned to daily oral prednisone with a slow taper with good effect and no recurrence of lesions.
ABSTRACT
Primary prostate cancer almost always has a luminal phenotype. However, little is known about the stem/progenitor properties of transformed cells within tumors. Using the aggressive Pten/Tp53-null mouse model of prostate cancer, we show that two classes of luminal progenitors exist within a tumor. Not only did tumors contain previously described multipotent progenitors, but also a major population of committed luminal progenitors. Luminal cells, sorted directly from tumors or grown as organoids, initiated tumors of adenocarcinoma or multilineage histological phenotypes, which is consistent with luminal and multipotent differentiation potentials, respectively. Moreover, using organoids we show that the ability of luminal-committed progenitors to self-renew is a tumor-specific property, absent in benign luminal cells. Finally, a significant fraction of luminal progenitors survived in vivo castration. In all, these data reveal two luminal tumor populations with different stem/progenitor cell capacities, providing insight into prostate cancer cells that initiate tumors and can influence treatment response.
Subject(s)
Adenocarcinoma/pathology , Neoplastic Stem Cells/pathology , Prostatic Neoplasms/pathology , Animals , Cell Lineage , Cell Separation , Disease Models, Animal , Epithelial Cells/pathology , Flow Cytometry , Male , Mice , Mice, Inbred NOD , Mice, Knockout , Mice, SCID , Organoids , PhenotypeABSTRACT
Bone metastasis is the hallmark of progressive and castration-resistant prostate cancers. MicroRNA 1 (miR-1) levels are decreased in clinical samples of primary prostate cancer and further reduced in metastases. SRC has been implicated as a critical factor in bone metastasis, and here we show that SRC is a direct target of miR-1. In prostate cancer patient samples, miR-1 levels are inversely correlated with SRC expression and a SRC-dependent gene signature. Ectopic miR-1 expression inhibited extracellular signal-regulated kinase (ERK) signaling and bone metastasis in a xenograft model. In contrast, SRC overexpression was sufficient to reconstitute bone metastasis and ERK signaling in cells expressing high levels of miR-1. Androgen receptor (AR) activity, defined by an AR output signature, is low in a portion of castration-resistant prostate cancer. We show that AR binds to the miR-1-2 regulatory region and regulates miR-1 transcription. Patients with low miR-1 levels displayed correlated low canonical AR gene signatures. Our data support the existence of an AR-miR-1-SRC regulatory network. We propose that loss of miR-1 is one mechanistic link between low canonical AR output and SRC-promoted metastatic phenotypes.
Subject(s)
Androgens/genetics , Bone Neoplasms/genetics , Bone Neoplasms/secondary , MicroRNAs/genetics , Prostatic Neoplasms, Castration-Resistant/genetics , src-Family Kinases/genetics , Animals , Bone Neoplasms/pathology , Cell Line, Tumor , Extracellular Signal-Regulated MAP Kinases/genetics , Gene Expression Regulation, Neoplastic/genetics , Humans , Male , Mice , Mice, Nude , Prostatic Neoplasms, Castration-Resistant/pathology , Receptors, Androgen/genetics , Signal Transduction/geneticsABSTRACT
The capability of electrospray ionization-conventional ion mobility spectrometry (ESI-IMS) for direct analysis of the samples extracted by solid phase microextraction (SPME) was investigated and evaluated for the first time. To that end, an appropriate new desorption chamber was designed and constructed, resulting in the possibility of direct exposure of the SPME fiber to the electrospray solvent flow. Two different elution methods in dynamic and static modes were exhaustively investigated. The results indicated that the interface could help us to have an accurate and sensitive analysis without disturbing the electrospray process, in static elution method. Venlafaxine as a test compound was extracted from human urine and plasma by a convenient headspace SPME method. The positive ion mobility spectrum of the extracted drug was obtained and the analyte responses were calculated. The coupled method of SPME-ESI-IMS was comprehensively validated in terms of sensitivity, dynamic range, and recovery percentage. Finally, various real samples of human urine and plasma were analyzed, all verifying the feasibility and success of the proposed method for the easy routine analysis.
Subject(s)
Blood Chemical Analysis/methods , Cyclohexanols/analysis , Cyclohexanols/isolation & purification , Solid Phase Microextraction/methods , Spectrometry, Mass, Electrospray Ionization/methods , Urinalysis/methods , Adult , Animals , Cyclohexanols/blood , Cyclohexanols/urine , Humans , Hydrogen-Ion Concentration , Male , Rats , Reproducibility of Results , Salts/chemistry , Temperature , Time Factors , Venlafaxine HydrochlorideABSTRACT
BACKGROUND: Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with high mutational heterogeneity and a generally poor clinical outcome. Despite implicated roles of deregulated TP53, IGF-2 and Wnt signaling pathways, a clear genetic association or unique mutational link to the disease is still missing. Recent studies suggest a crucial role for epigenetic modifications in the genesis and/or progression of ACC. This study specifically evaluates the potential role of epigenetic silencing of RASSF1A, the most commonly silenced tumor suppressor gene, in adrenocortical malignancy. RESULTS: Using adrenocortical tumor and normal tissue specimens, we show a significant reduction in expression of RASSF1A mRNA and protein in ACC. Methylation-sensitive and -dependent restriction enzyme based PCR assays revealed significant DNA hypermethylation of the RASSF1A promoter, suggesting an epigenetic mechanism for RASSF1A silencing in ACC. Conversely, the RASSF1A promoter methylation profile in benign adrenocortical adenomas (ACAs) was found to be very similar to that found in normal adrenal cortex. Enforced expression of ectopic RASSF1A in the SW-13 ACC cell line reduced the overall malignant behavior of the cells, which included impairment of invasion through the basement membrane, cell motility, and solitary cell survival and growth. On the other hand, expression of RASSF1A/A133S, a loss-of-function mutant form of RASSF1A, failed to elicit similar malignancy-suppressing responses in ACC cells. Moreover, association of RASSF1A with the cytoskeleton in RASSF1A-expressing ACC cells and normal adrenal cortex suggests a role for RASSF1A in modulating microtubule dynamics in the adrenal cortex, and thereby potentially blocking malignant progression. CONCLUSIONS: Downregulation of RASSF1A via promoter hypermethylation may play a role in the malignant progression of adrenocortical carcinoma possibly by abrogating differentiation-promoting RASSF1A- microtubule interactions.