Significant and Various Effects of ML329-Induced MITF Suppression in the Melanoma Cell Line.

To study the inhibitory effects on microphthalmia-associated transcription factor (MITF)-related biological aspects in malignant melanomas (MMs) in the presence or absence of the low-molecular MITF specific inhibitor ML329, cell viability, cellular metabolic functions, and three-dimensional (3D) spheroid formation efficacy were compared among MM cell lines including SK-mel-24, A375, dabrafenib- and trametinib-resistant A375 (A375DT), and WM266-4. Upon exposure to 2 or 10 µM of ML329, cell viability was significantly decreased in WM266-4, SK-mel-24, and A375DT cells, but not A375 cells, in a dose-dependent manner, and these toxic effects of ML329 were most evident in WM266-4 cells. Extracellular flux assays conducted using a Seahorse bioanalyzer revealed that treatment with ML329 increased basal respiration, ATP-linked respiration, proton leakage, and non-mitochondrial respiration in WM266-4 cells and decreased glycolytic function in SK-mel-24 cells, whereas there were no marked effects of ML329 on A375 and A375DT cells. A glycolytic stress assay under conditions of high glucose concentrations also demonstrated that the inhibitory effect of ML329 on the glycolytic function of WM266-4 cells was dose-dependent. In addition, ML329 significantly decreased 3D-spheroid-forming ability, though the effects of ML329 were variable among the MM cell lines. Furthermore, the mRNA expression levels of selected genes, including STAT3 as a possible regulator of 3D spheroid formation, KRAS and SOX2 as oncogenic-signaling-related factors, PCG1a as the main regulator of mitochondrial biogenesis, and HIF1a as a major hypoxia transcriptional regulator, fluctuated among the MM cell lines, possibly supporting the diverse ML329 effects mentioned above. The findings of diverse ML329 effects on various MM cell lines suggest that MITF-associated biological activities are different among various types of MM.

Tumor cell-induced platelet aggregation accelerates hematogenous metastasis of malignant melanoma by triggering macrophage recruitment.

BACKGROUND: Tumor cell-induced platelet aggregation (TCIPA) is not only a recognized mechanism for paraneoplastic thrombocytosis but also a potential breakthrough alternative for a low response to immune checkpoint inhibitors (ICIs) in hematogenous metastasis of malignant melanoma (MM). However, there is no TCIPA-specific model for further investigation of the relationship among TCIPA, the tumor immune microenvironment (TIME), and metastasis. METHODS: We developed a TCIPA metastatic melanoma model with advanced hematogenous metastasis and enhanced TCIPA characteristics. We also investigated the pathway for TCIPA in the TIME. RESULTS: We found that TCIPA triggers the recruitment of tumor-associated macrophages (TAMs) to lung metastases by secreting B16 cell-educated platelet-derived chemokines such as CCL2, SDF-1, and IL-1ß. Larger quantities of TAMs in the TCIPA model were polarized to the M2 type by B16 cell reprocessing, and their surface programmed cell death 1 ligand 1 (PD-L1) expression was upregulated, ultimately assisting B16 cells in escaping host immunity and accelerating MM hematogenous metastasis. CONCLUSIONS: TCIPA accelerates MM lung metastasis via tumor-educated platelets (TEPs), triggering TAM recruitment, promoting TAM polarization (M2), and remodeling the suppressive TIME in lung metastases.

Investigation of the Effect on the Albumin Binding Moiety for the Pharmacokinetic Properties of 68Ga-, 205/206Bi-, and 177Lu-Labeled NAPamide-Based Radiopharmaceuticals.

Although radiolabeled alpha-melanocyte stimulating hormone-analogue NAPamide derivatives are valuable melanoma-specific diagnostic probes, their rapid elimination kinetics and high renal uptake may preclude them from being used in clinical settings. We aimed at improving the pharmacokinetics of radiolabeled DOTA-NAPamide compounds by incorporating a 4-(p-iodo-phenyl)-butanoic acid (IPB) into the molecules. Followed by 68Ga-, 205/206Bi-, and 177Lu-labelling, the radiopharmaceuticals ([68Ga]Ga-DOTA-IPB-NAPamide, [205/206Bi]Bi-DOTA-IPB-NAPamide, [177Lu]Lu-DOTA-IPB-NAPamide) were characterized in vitro. To test the imaging behavior of the IPB-containing probes, B16F10 tumor-bearing C57BL/6 mice were subjected to in vivo microPET/microSPECT/CT imaging and ex vivo biodistribution studies. All tracers were stable in vitro, with radiochemical purity exceeding 98%. The use of albumin-binding moiety lengthened the in vivo biological half-life of the IPB-carrying radiopharmaceuticals, resulting in elevated tumor accumulation. Both [68Ga]Ga-DOTA-IPB-NAPamide (5.06 ± 1.08 %ID/g) and [205/206Bi]Bi-DOTA-IPB-NAPamide (4.50 ± 0.98 %ID/g) exhibited higher B16F10 tumor concentrations than their matches without the albumin-binding residue ([68Ga]Ga-DOTA-NAPamide and [205/206Bi]Bi-DOTA-NAPamide: 1.18 ± 0.27 %ID/g and 3.14 ± 0.32; respectively), however; the large amounts of off-target radioactivity do not confirm the benefits of half-life extension for short-lived isotopes. Enhanced [177Lu]Lu-DOTA-IPB-NAPamide tumor uptake even 24 h post-injection proved the advantage of IPB-based prolonged circulation time regarding long-lived radionuclides, although the significant background noise must be addressed in this case as well.

Carpal Tunnel Syndrome Associated with Immune Checkpoint Inhibitors.

Immune checkpoint inhibitors (ICIs) have transformed the therapeutic approach to diverse malignancies, leading to substantial enhancements in patient prognosis. However, along with their benefits, ICIs also increase the incidence of immune-related adverse events (irAEs). In the present paper, we highlight four cases of carpal tunnel syndrome (CTS) as an uncommon manifestation of toxicity induced by ICIs. Although diagnosed with different malignancies, the patients were undergoing ICI therapy when they developed CTS-consistent side effects accompanied by severe neuropathy. Prompt treatment with corticosteroids, intravenous immunoglobulins, or methotrexate resulted in complete symptomatic relief for all patients. This article therefore emphasizes the importance of recognizing and managing rare adverse events associated with ICI use to ensure optimal patient care.

Investigation of oncolytic effect of recombinant Newcastle disease virus in primary and metastatic oral melanoma.

Malignant melanoma is aggressive cancer with a high rate of local invasiveness and metastasis. Currently, the treatment options for patients with advanced-stage and metastatic oral melanoma are limited. A promising treatment option is oncolytic viral therapy. This study aimed to evaluate novel therapies for malignant melanoma using a canine model. Oral melanoma, which frequently occurs in dogs is used as a model for human melanoma, was isolated and cultured and used for the evaluation of the tumor lytic effect induced by viral infection. We constructed a recombinant Newcastle disease virus (rNDV) that promotes the extracellular release of IFNγ from the virus-infected melanoma. The expression of oncolytic and apoptosis-related genes, the immune response by lymphocytes, and IFNγ expression were evaluated in virus-infected melanoma cells. The results showed that the rate of rNDV infection varied according to the isolated melanoma cells and the oncolytic effect differed between melanoma cells owing to the infectivity of the virus. The oncolytic effect tended to be greater for the IFNγ-expressing virus than for the GFP-expressing prototype virus. Additionally, lymphocytes co-cultured with the virus showed induced expression of Th1 cytokines. Therefore, recombinant NDV expressing IFNγ is expected to induce cellular immunity and oncolytic activity. This oncolytic treatment shows promise as a therapeutic approach for melanoma treatment once evaluated using clinical samples from humans.

Case Report: Malignant Melanoma Associated With COVID-19: A Coincidence or a Clue?

Following SARS-CoV-2 infection in humans, there is upregulation of proinflammatory molecules S100 calcium binding protein B (S100B), high-mobility group box-1 (HMGB1), osteopontin (OPN), tumor necrosis factor alpha (TNF-α), and other cytokines that promote hyperinflammation. The same immunoregulatory proteins that fuel the COVID-19 "cytokine storm" are also produced by melanoma cells and various other cancers to promote tumorigenesis. We report three cases of malignant melanoma (MM) associated with severe COVID-19, the first two with amelanotic melanoma and the third with hypopigmented melanoma. It is noteworthy that we did not search for these cases. Patient 1 is a personal acquaintance and cases 2 and 3 were hospitalized and worked at our rehabilitation center, respectively. We hypothesize that SARS-CoV-2 induced inflammatory tumorigenic proteins in the microenvironment that may have contributed to the de novo development (case 1), aggressive growth (case 2), or recurrence (case 3) of these malignant tumors. Moreover, high concentrations of the same proinflammatory proteins found in the "cytokine storm" associated with COVID-19, including TNF-α, interleukin (IL)-1α, IL-1ß, IL-6, and ferritin, also induce skin depigmentation or hypopigmentation by interfering with tyrosinase synthesis, the enzyme that catalyzes the rate-limiting step of pigmentation. Hence, the marked elevation of the biological effectors that decrease skin pigmentation may also reduce pigmentation in MMs, resulting in amelanotic or hypopigmented lesions. Although it is certainly possible that the occurrence of melanoma following COVID-19 is coincidental, the ability of SARS-CoV-2 to increase expression of proinflammatory and tumorigenic molecules warrants further investigations to determine if there is an association between these disease processes or implications for patients with melanoma or other cancers who develop COVID-19.

The Use of 18F-FDG PET/CT Metabolic Parameters in Predicting Overall Survival in Patients Undergoing Restaging for Malignant Melanoma.

Malignant melanoma is one of the more aggressive cancers in the skin, with an increasing incidence every year. Melanoma has a better prognosis if diagnosed early and survival tends to decrease once the disease has metastasized. Positron emission tomography (PET) with 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) has been used extensively over the past two decades in staging and assessing responses to therapy in patients with melanoma. Metabolic PET parameters have been demonstrated to be independent prognostic factors for progression-free survival (PFS) and overall survival (OS) in different malignancies, melanoma included. In our study, we evaluated the metabolic parameters of 18F-FDG PET/CT (flourodeoxyglucose positron emission tomography/computed tomography) in predicting the overall survival in patients with malignant melanoma who presented for restaging. Metabolic PET parameters (maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG)) of the primary tumor, as well as whole-body MTV and TLG of the metastatic disease, were measured. Survival curves for OS were constructed and mortality rates were determined using the different PET variables. Forty-nine patients who presented for a PET/CT restaging in melanoma were included in this study. We found that non-survivors had significantly higher median MTV (11.86 cm3 vs. 5.68 cm3; p-value = 0.022), TLG (3125 vs. 14; p-value = 0.0357), whole-body MTV (53.9 cm3 vs. 14.4 cm3; p-value = 0.0076) and whole-body TLG (963.4 vs. 114.6; p-value = 0.0056). This demonstrated that high MTV and TLG values of the primary tumor and whole-body TLG as quantified by 18F-FDG PET/CT were prognostic factors for overall survival. The findings may potentially guide clinicians in decision making and identifying patients with a poorer prognosis.

Bioinformatics analysis identifies PSMB8 as a key gene in the cutaneous malignant melanoma tumor microenvironment.

Background: Cutaneous tumors are commonly seen in clinical practice, and malignant melanoma (MM) is the leading cause of cutaneous tumor-induced death. The tumor microenvironment (TME), a critical part of tumorigenesis, has been a research hotspot in recent years. However, the effects of the MM microenvironment components remain elusive. This study aimed to analyze the various components in the TME of MM to identify factors affecting the tumorigenesis, progression, and metastasis of MM and the survival of MM patients. We also aimed to identify biomarkers related to TME rehabilitation to provide a new direction for MM treatment. Methods: We used bioinformatics to analyze the RNA-seq and somatic mutation data of 473 MM patients from The Cancer Genome Atlas database. Firstly, the patients' immunity and stroma were separately scored by the Estimation of STromal and Immune cells in MAlignant Tumor tissues using Expression data (ESTIMATE) method. According to the median score, the participants were split into high- and low-score groups. Then, Gene Set Enrichment Analysis (GSEA) was performed, showing that high-expression genes were highly abundant in biological and metabolic activities associated with the immune system. Results: Differentially expressed genes (DEGs) and differentially mutated genes (DMGs) were identified and intersected to obtain the key immune-related genes PSMB8, FAM216B, DYSF, and FAM131C. PSMB8 was finally selected as the preferred immune-related prognostic marker; it was positively associated with overall survival and therefore considered a protective gene for MM patients. The GSEA analysis showed that PSMB8 with high expression had greater gene abundance in biological and metabolic processes related to immune system. In addition, CIBERSORT analysis showed an association between the proportion of tumor-infiltrating immune cells and PSMB8 expression. Conclusions: Our results suggest that PSMB8 might be associated with tumorigenesis and MM progression and could serve as a biomarker for the TME rehabilitation of MM. Our findings provide a new perspective and direction for the treatment of MM.

Dedifferentiated Melanoma: A Diagnostic Histological Pitfall-Review of the Literature with Case Presentation.

Dedifferentiated melanoma is a particular form of malignant melanoma with a progressive worsening of the patient's clinical outcome. It is well known that melanoma can assume different histo-morphological patterns, to which specific genetic signatures correspond, sometimes but not always. In this review we address the diagnostic difficulties in correctly recognizing this entity, discuss the major differential diagnoses of interest to the dermatopathologist, and conduct a review of the literature with particular attention and emphasis on the latest molecular discoveries regarding the dedifferentiation/undifferentiation mechanism and more advanced therapeutic approaches.

Prolonged survival following everolimus combined with temozolomide for metastatic malignant melanoma with FBXW7 mutation: a case report and literature review.

Metastatic unresectable malignant melanoma (MM) owing to its intrinsic biological invasion potential and low sensitivity to radiochemotherapy has a poor prognosis and a high rate of mortality; the mean survival period is only 6-8 months, and the 5-year survival rate is less than 10%. The progression of patients with brain and liver metastases is worse than those with other distant or visceral metastases. With the advent of immunotherapy, especially immune-checkpoint inhibitors, long-term remission of stage IV disease may be achieved in some patients. Despite recent advances, not all patients benefit or can afford immunotherapy. Here, we report the case of a 44-year-old man whose initial diagnosis was MM with liver and multiple brain metastases. A high expression of F-box/WD repeat-containing protein 7 (FBXW7) inactivating mutation was observed, and the patient was treated with a combination of everolimus and temozolomide (TMZ) following palliative radiotherapy. The patient was stable for approximately 17 months, and eventually showed an overall survival (OS) of about 19 months. This case is novel and instructional, which highlights that the combination of everolimus and TMZ might be effective, with manageable toxicity, for advanced MM patients with FBXW7 mutation. And it may provide a reference for the treatment of analogous patients.

Clinical ABCDE rule for early melanoma detection.

BACKGROUND: The ABCDE rule systematizes warning signs for malignant melanoma (MM). OBJECTIVES: To evaluate whether the ABCDE signs are associated with early detection of MM. MATERIALS & METHODS: Based on a retrospective study over 11.5 years, we assessed whether ABCDE signs are associated with early diagnosis of MM. RESULTS: In total, 144 MM were included; 52 (36.1%) in situ and 92 (63.9%) invasive lesions. For 23.6%, the MM were first suspected by an individual other than a dermatologist. The "E sign" was significantly less frequent among in situ lesions (32.7% versus 50.0%; p = 0.044). Based on adjusted analyses, the probability of MM being first suspected by a non-dermatologist consistently increased with the number of ABCDE signs of the lesion, ranging from 8% for a neoplasm with no ABCDE signs to 32% for a lesion with five signs (OR = 1.6; 95% CI: 1.2-2.2; p = 0.004). CONCLUSION: A higher number of ABCDE signs were associated with a greater chance of MM being first suspected by a non-dermatologist, but not in situ MM diagnosis. Relying on the ABCDE rule alone might result in missing early MM lesions.

Analysis of the surgical management of skin cancer in the nonagenarian population: Twenty-five year data analysis from a single centre.

BACKGROUND: There were 142,101 new cases of non-melanomatous skin cancers reported by the UK National Cancer Statistics in 2015. The UK statistics published that the incidence is highest in the 90+ population and that this represented an overall 61% increase in skin cancer incidence in the UK in the last decade. This article aims to first provide an understanding of the change in service requirement over the last 25 years for skin cancer management in nonagenarians, and second, understand the subtypes of skin cancer and possible differences in the management for this cohort. METHODS: All skin cancer biopsies received by a UK university teaching hospital dermato-histopathology department were analysed over a five-year period spanning 2013-2017. This was compared with snap shot data at five-year intervals dating back to 1993. The patient demographics including age, sex and anatomical region were seen along with the types of skin cancers and histological subtypes. RESULTS: A total of 1050 skin cancers were managed with surgical input between January 2013 and December 2017 in 733 patients. The number of biopsies/year has increased 7-fold from 1993 (33) to 2017 (231). The annual cost of the surgical element to this service has dramatically increased, and in 2017, it was £220k compared to £33k in 1993. CONCLUSION: Partly because of the ageing UK population, there has been a dramatic increase in the demand on the surgical service regarding managing skin cancers in those over the age of 90. There is a higher rate of incomplete excision in this population than that reported in the national British Association of Dermatologists (BAD) guidelines. Despite higher incomplete excision rates, there is a low re-operation rate in this population probably due to patient comorbidities affecting reconstructive options, patient preference and clinical decisions on surgical morbidity versus benefit.

Malignant melanoma of parotid gland in a child-our unique experience.

Malignant melanoma (MM) of parotid gland is a rare condition. This pathology is often a result of secondary metastasis from primary lesions in the head and neck skin. A MM arising de novo in parotid gland is very rare. This malignant tumour is more prevalent in adults rather than children and it tends to have several distinct features. Treatment options are limited especially for an advanced lesion. Despite best treatments this condition carries a poor prognosis. This case details our experience in treating a child with MM of parotid gland without other primary cutaneous lesions.

Lasers and intense pulsed light (IPL) association with cancerous lesions.

The development and use of light and lasers for medical and cosmetic procedures has increased exponentially over the past decade. This review article focuses on the incidence of reported cases of skin cancer post laser or IPL treatment. The existing evidence base of over 25 years of laser and IPL use to date has not raised any concerns regarding its long-term safety with only a few anecdotal cases of melanoma post treatment over two decades of use; therefore, there is no evidence to suggest that there is a credible cancer risk. Although laser and IPL technology has not been known to cause skin cancer, this does not mean that laser and IPL therapies are without long-term risks. Light therapies and lasers to treat existing lesions and CO2 laser resurfacing can be a preventative measure against BCC and SCC tumour formation by removing photo-damaged keratinocytes and encouraged re-epithelisation from stem cells located deeper in the epidermis. A review of the relevant literature has been performed to address the issue of long-term IPL safety, focussing on DNA damage, oxidative stress induction and the impact of adverse events.

Recurrence Rate of Melanoma in Situ when Treated with Serial Disk Staged Excision: A Case Series.

BACKGROUND: Cutaneous melanoma is one of the fastest rising cancer diagnoses in recent years. Melanoma in situ (MIS) constitutes a large proportion of all diagnosed melanomas. While surgical excision is considered the standard of therapy, the literature is not clear on which surgical technique minimizes local recurrence. A common technique is serial staged excision (SSE), in which a series of mapped excisions are made according to histopathological examination of tissue. Previously published recurrence rates for SSE ranges from 0-12%, over a range of 4.7-97 months of mean follow-up. OBJECTIVE: To investigate the recurrence rate of MIS when excised using a serial disk staged excision technique with tissue marked at 12 O'clock for mapping, rush permanent processing and histologic examination, 3-suture tagging for subsequent stages, and "breadloafing" microscopic analysis. Additionally, to determine the relationship between initial lesion size and subsequent stages of excision required for clearance, and final surgical margin. METHODS: Single-institution retrospective chart review of 29 biopsy confirmed MIS lesions treated with our variant of SSE. Statistical analysis via independent t-tests. RESULTS: No recurrences were observed with mean follow-up of 31.5 months (SD 13.9), over range of 12-58 months. Mean surgical margin of 13.1 mm (SD 5.9). A trend towards larger surgical margin was seen with increasing pre-operative lesion size. CONCLUSION: This method of SSE for treatment of MIS is comparable in efficacy to other SSE techniques, and may offer physicians a relatively simple, efficacious, and accessible alternative to wide local excision and Mohs micrographic surgery.

Mechanisms of Tanshinone II a inhibits malignant melanoma development through blocking autophagy signal transduction in A375 cell.

BACKGROUND: Malignant melanoma (MM) is one of the high degree of malignancy and early prone to blood and lymph node metastasis. There is not cured for MM. Tan II A has been reported to reduce cancer cell proliferation. But the mechanism by which Tan II A inhibited melanoma growth are not well characterized. We sought to explore the possible mechanism by which Tan II A regulated cell proliferation through autophagy signaling pathway in A375 cells. METHODS: We tested the effects of Tan II A on melanoma A375, MV3, M14, and other human cell lines including Hacat and HUVEC cells in cell culture model. Cell proliferation was assessed by using methyl thiazol tetrazolium (MTT) assay. Cell migration ability melanoma A375 was monitored by using cell scratch assay. Transwell chamber experimental was performed to assess the effect of Tan II A on A375 melanoma cell invasion ability. The autophagy body was examined by using flow cytometry. The expression of autophagy-associated protein beclin-1 and microtubule-associated protein 1 light chain 3(LC3)-II, as well as phosphatidylinositol 3-kinase(PI3K)、protein kinase B (Akt)、mammalian target of rapamycin (mTOR)、p70S6K1 signaling pathways were detected by using Western blotting. The effects of Tan II A on tumor progression was also examined in melanoma A375 induced tumor in mouse model. RESULTS: We found that Tan IIA inhibited melanoma A375, MV3, and M14 cell proliferation in dose and time dependent manner. Tan II A reduced CXCL12-induced A375 cell invasive ability and migration in a dose dependent manner. Tan IIA promoted autophagic body production and increased autophagy-associated protein beclin-1 and LC3-II expression in A375 cells. However, Tan IIA reduced the phosphorylation of PI3K, P-AKT, P-mTOR, and P-p7036k1. We also confirmed that Tan II A reduced melanoma A375 induced tumor volume and weight in mouse model. CONCLUSIONS: We concluded that Tan II A reduced A375 cells proliferation by activation of autophagy production, blocked PI3K- Akt - mTOR - p70S6K1 signaling pathway, increased autophagic related gene beclin-1, LC3-II protein expressions and induced autophagocytosis. Tan II A inhibited melanoma A375 induced tumor development in mouse model.

MicroRNA-365 inhibits growth, invasion and metastasis of malignant melanoma by targeting NRP1 expression.

OBJECTIVE: The role of miR-365 in cancer cells seemed controversial in previous studies. We thereby in this article aimed to define the role of miR-365 in malignant melanoma (MM) pathogenesis. METHODS: We detected miR-365 expression in malignant melanoma cell lines and then investigated the effects of miR-365 on the metastasis and malignancy of melanoma cells. The correlation between miR-365 level and NRP1 (neuropilin1) was further investigated in clinical malignant melanoma specimens. RESULTS: MiR-365 was strongly down-regulated in malignant melanoma (MM) tissues and cell lines, and its expression levels were associated with lymph node metastasis and clinical stage, as well as overall survival and replase-free survival of MM. We also found that ectopic expression of miR-365 inhibited MM cell proliferation and MM metastasis in vitro and in vivo. We further identified a novel mechanism of miR-365 to suppress MM growth and metastasis. NRP1 was proved to be a direct target of miR-365, using luciferase assay and western blot. NRP1 over-expression in miR-365 expressing cells could rescue invasion and growth defects of miR-365. In addition, miR-365 expression inversely correlated with NRP1 protein levels in MM. CONCLUSION: Our data suggest that miR-365 functions as a tumor suppressor in MM development and progression, and holds promise as a prognostic biomarker and potential therapeutic target for MM.

MicroRNA-365 inhibits growth, invasion and metastasis of malignant melanoma by targeting NRP1 expression.

OBJECTIVE: The role of miR-365 in cancer cells seemed controversial in previous studies. We thereby in this article aimed to define the role of miR-365 in malignant melanoma (MM) pathogenesis. METHODS: We detected miR-365 expression in malignant melanoma cell lines and then investigated the effects of miR-365 on the metastasis and malignancy of melanoma cells. The correlation between miR-365 level and NRP1 (neuropilin1) was further investigated in clinical malignant melanoma specimens. RESULTS: MiR-365 was strongly down-regulated in malignant melanoma (MM) tissues and cell lines, and its expression levels were associated with lymph node metastasis and clinical stage, as well as overall survival and replase-free survival of MM. We also found that ectopic expression of miR-365 inhibited MM cell proliferation and MM metastasis in vitro and in vivo. We further identified a novel mechanism of miR-365 to suppress MM growth and metastasis. NRP1 was proved to be a direct target of miR-365, using luciferase assay and western blot. NRP1 over-expression in miR-365 expressing cells could rescue invasion and growth defects of miR-365. In addition, miR-365 expression inversely correlated with NRP1 protein levels in MM. CONCLUSION: Our data suggest that miR-365 functions as a tumor suppressor in MM development and progression, and holds promise as a prognostic biomarker and potential therapeutic target for MM.