BRAF Heterogeneity in Melanoma

Effective detection of BRAFV595E mutation in canine urothelial and prostate carcinomas using immunohistochemistry

Canine urothelial carcinoma (UC) and prostate carcinoma (PC) frequently exhibit the BRAFV595E mutation, akin to the BRAFV600E mutation common in various human cancers. Since the initial discovery of the BRAF mutation in canine cancers in 2015, PCR has been the standard method for its detection in both liquid and tissue biopsies. Considering the similarity between the canine BRAFV595E and human BRAFV600E mutations, we hypothesized that immunohistochemistry (IHC) using a BRAFV600E-specific antibody could effectively identify the canine mutant BRAFV595E protein. We tested 122 canine UC (bladder n = 108, urethra n = 14), 21 PC, and benign tissue using IHC and performed digital droplet PCR (ddPCR) on all 122 UC and on 14 IHC positive PC cases. The results from ddPCR and IHC were concordant in 99% (135/136) of the tumours. Using IHC, BRAFV595E was detected in 72/122 (59%) UC and 14/21 (65%) PC. Staining of all benign bladder and prostate tissues was negative. If present, mutant BRAF staining was homogenous, with rare intratumour heterogeneity in three (4%) cases of UC. Additionally, the BRAFV595E mutation was more prevalent in tumours with urothelial morphology, and less common in glandular PC or UC with divergent differentiation. This study establishes that BRAFV600-specific IHC is a reliable and accurate method for detecting the mutant BRAFV595E protein in canine UC and PC. Moreover, the use of IHC, especially with tissue microarrays, provides a cost-efficient test for large-scale screening of canine cancers for the presence of BRAF mutations. This advancement paves the way for further research to define the prognostic and predictive role of this tumour marker in dogs and use IHC to stratify dogs for the treatment with BRAF inhibitors.

Current State of Melanoma Therapy and Next Steps: Battling Therapeutic Resistance

Melanoma is the most aggressive and deadly form of skin cancer due to its high propensity to metastasize to distant organs. Significant progress has been made in the last few decades in melanoma therapeutics, most notably in targeted therapy and immunotherapy. These approaches have greatly improved treatment response outcomes; however, they remain limited in their abilities to hinder disease progression due, in part, to the onset of acquired resistance. In parallel, intrinsic resistance to therapy remains an issue to be resolved. In this review, we summarize currently available therapeutic options for melanoma treatment and focus on possible mechanisms that drive therapeutic resistance. A better understanding of therapy resistance will provide improved rational strategies to overcome these obstacles.

Primary Hepatic Melanoma: A Diagnostic Surprise

Melanoma is a relatively rare malignancy with a highly aggressive biological behavior. Metastases to other sites, like lymph nodes and liver are common, but primary hepatic melanoma is a rarity with poor survival ranging from months to few years. Diagnosis of primary hepatic melanoma via clinical features and imaging technology is difficult because of its ambiguous features. Here, we present a 26-year-old North Indian woman admitted in the department of gastrointestinal surgery at our tertiary care hospital with the complaint of pain in the abdomen for a month associated with the loss of appetite and subsequent weight loss. The liver function tests were within normal limits and viral markers were negative. The triple-phase computed tomography scan of abdomen showed significant hepatomegaly and two well-defined lesions in both lobes of the liver. Histopathological evaluation was performed on the core liver biopsies submitted from the liver lesions. A malignant tumor with abundant black intracytoplasmic pigment was identified. Immunohistochemistry proved the tumor to be melanoma. The detailed clinical history, laboratory, and radiological investigations were acquired and analyzed to rule out a metastatic lesion of the same. A final diagnosis of primary hepatic melanoma was thus rendered. Primary hepatic melanoma is extremely uncommon and has been rarely reported. Preoperative diagnosis is challenging due to low index of suspicion and nonspecific clinical features. In this case report, we discuss the clinicopathological features of primary hepatic melanoma and review the literature so as to increase the awareness and improve our understanding of the disease.

Identification of a novel genomic variance of BRAF1 in papillary thyroid carcinoma: A case report

RATIONALE

Papillary thyroid carcinoma (PTC), the predominant subtypes accounting for approximately 85% of thyroid carcinomas, has a rapidly increasing global incidence rate. Statistically, approximately 74.6% PTC patients had the genomic variants of BRAF, especially BRAFV600E mutation, which has been reported to stratify patients and guide clinic-therapies. However, some PTC patients may carry other nonclassical mutation patterns of BRAF, due to the complex of genomic instability. And the spectrum of BRAF mutation was not fully characterized. We reported a novel BRAF mutation pattern of PTC.

PATIENT CONCERNS

A 59-year-old woman was admitted to our hospital because of the slight enlargement of bilateral cervical lymph nodes in July 2023.

DIAGNOSIS

Ultrasonography revealed that the bilateral thyroid nodules of the patients both presented 1 hypoechoic nodule, which was graded as 3 of the elastic score, and the small calcification in the right lobe (Chinese-Thyroid Imaging Reporting and Data System 4c). Pathological diagnosis showed the interstitial collagen change and focal follicular epithelial papillary hyperplasia with atypical hyperplasia of the bilateral thyroid. Further puncture pathology showed that the patient had a malignant thyroid lesion with the phenotypes of papillary carcinoma and diagnosed with malignancy subsequently. Additionally, the patient harbored a novel insert on BRAF exon 15, a 6-base fragment AGACAG inserting between c.1798 and c.1799.

INTERVENTIONS

The patient was undergone on microwave ablation of thyroid carcinoma on July 28, 2023. After the surgery, the patient was treated on anti-infection, cold saline external application of bilateral thyroid swelling supportive treatment.

OUTCOMES

No postoperative complications or recurrence and metastasis were found.

LESSONS

This is the first case of the novel nonclassical genomic variant of BRAF. Our study extends the spectrum of BRAF mutations. The patient had a favorable response to microwave ablation, indicating that in spite of the association between this mutation and high-grade malignant phenotype, this genomic variant of BRAF did not have a detrimental effect on the response of clinical treatment.

DSE inhibits melanoma progression by regulating tumor immune cell infiltration and VCAN

Dermatan sulfate epimerase (DSE) is a C5 epiminase that plays a key role in converting chondroitin sulfate into dermal sulfate. DSE is often upregulated during carcinogenesis of some types of cancer and can regulate growth factor signaling in cancer cells. However, the expression and function of DSE in human melanoma have not been reported. In this study, we investigated the influence of tumor-derived DSE in melanoma progression and the potential mechanism of their action. First, proteomic analysis of collected melanoma tissues revealed that DSE was significantly down-regulated in melanoma tissues. DSE silenced or overexpressed melanoma cells were constructed to detect the effect of DSE on melanoma cells, and it was found that the up-regulation of DSE significantly inhibited the proliferation, migration and invasion of melanoma cells. Data analysis and flow cytometry were used to evaluate the immune subpopulations in tumors, and it was found that the high expression of DSE was closely related to the invasion of killer immune cells. Mechanistically, DSE promoted the expression of VCAN, which inhibited the biological activity of melanoma cells. Together, these results suggest that DSE is downregulated in melanoma tissues, and that high expression of DSE can promote melanoma progression by inducing immune cell infiltration and VCAN expression.

Combinational photodynamic and photothermal - based therapies for melanoma in mouse models

BACKGROUND

Melanoma is a highly metastatic skin cancer with limited response to current therapies in advanced patients. To overcome resistance, novel treatments based on photodynamic and photothermal therapies (PDT and PTT, respectively) have been developed to treat melanoma in preclinical murine models. Despite success inhibiting implanted tumors' growth, there has been limited evaluation of their long-term effectiveness in preventing metastasis, recurrence, or improving survival rates.

METHODS

Combined and multidrug therapies based on PDT and/or PTT to treat cutaneous malignant melanoma in the preclinical mouse model were reviewed from 2016 onwards. PubMed® was the database in which the search was performed using mesh search algorithms resulting in fifty-one studies that comply with strict inclusion rules of screening.

RESULTS

B16 melanoma-bearing C57BLACK6 mice model was the most used to evaluate immunotherapies, chemotherapies, and targeted therapies in combination with PDT and/or PTT. Combined therapies demonstrated a synergistic effect, resulting in intense antitumor activity. The most extensively studied protocol for developing metastatic models involved the intravenous administration of malignant cells, with some combined therapies being tested. Furthermore, the review presents the composition of the nanostructures utilized for delivering the drugs and light-responsive agents and the treatment plans for each combined approach.

CONCLUSIONS

The identified mechanisms to simulate metastatic melanoma models and the therapeutic combinations may aid in evaluating the systemic protection of combined PDT and PTT-based therapies, particularly in conducting short-term preclinical experiments. Such simulations could have relevance to clinical studies.

Mutational landscape of cancer-driver genes across human cancers

The genetic mutations that contribute to the transformation of healthy cells into cancerous cells have been the subject of extensive research. The molecular aberrations that lead to cancer development are often characterised by gain-of-function or loss-of-function mutations in a variety of oncogenes and tumour suppressor genes. In this study, we investigate the genomic sequences of 20,331 primary tumours representing 41 distinct human cancer types to identify and catalogue the driver mutations present in 727 known cancer genes. Our findings reveal significant variations in the frequency of cancer gene mutations across different cancer types and highlight the frequent involvement of tumour suppressor genes (94%), oncogenes (93%), transcription factors (72%), kinases (64%), cell surface receptors (63%), and phosphatases (22%), in cancer. Additionally, our analysis reveals that cancer gene mutations are predominantly co-occurring rather than exclusive in all types of cancer. Notably, we discover that patients with tumours displaying different combinations of gene mutation patterns tend to exhibit variable survival outcomes. These findings provide new insights into the genetic landscape of cancer and bring us closer to a comprehensive understanding of the underlying mechanisms driving the development of various forms of cancer.

Artificial Intelligence to Predict the BRAF V595E Mutation in Canine Urinary Bladder Urothelial Carcinomas

In dogs, the BRAF mutation (V595E) is common in bladder and prostate cancer and represents a specific diagnostic marker. Recent advantages in artificial intelligence (AI) offer new opportunities in the field of tumour marker detection. While AI histology studies have been conducted in humans to detect BRAF mutation in cancer, comparable studies in animals are lacking. In this study, we used commercially available AI histology software to predict BRAF mutation in whole slide images (WSI) of bladder urothelial carcinomas (UC) stained with haematoxylin and eosin (HE), based on a training (n = 81) and a validation set (n = 96). Among 96 WSI, 57 showed identical PCR and AI-based BRAF predictions, resulting in a sensitivity of 58% and a specificity of 63%. The sensitivity increased substantially to 89% when excluding small or poor-quality tissue sections. Test reliability depended on tumour differentiation (p < 0.01), presence of inflammation (p < 0.01), slide quality (p < 0.02) and sample size (p < 0.02). Based on a small subset of cases with available adjacent non-neoplastic urothelium, AI was able to distinguish malignant from benign epithelium. This is the first study to demonstrate the use of AI histology to predict BRAF mutation status in canine UC. Despite certain limitations, the results highlight the potential of AI in predicting molecular alterations in routine tissue sections.

A step forward on the in vitro and in vivo assessment of a novel nanomedicine against melanoma

Melanoma is the most aggressive form of skin cancer, with increasing incidence and mortality rates. To overcome current treatment limitations, a hybrid molecule (HM) combining a triazene and a ʟ-tyrosine analogue, was recently synthesized, incorporated in long blood circulating liposomes (LIP HM) and validated in an immunocompetent melanoma model. The present work constitutes a step forward in the therapeutic assessment of HM formulations. Here, human melanoma cells, A375 and MNT-1, were used and dacarbazine (DTIC), a triazene drug clinically available as first-line treatment for melanoma, constituted the positive control. In cell cycle analysis, A375 cells, after 24-h incubation with HM (60 μM) and DTIC (70 μM), resulted in a 1.2 fold increase (related to control) in the percentage of cells in G0/G1 phase. The therapeutic activity was evaluated in a human murine melanoma model (subcutaneously injected with A375 cells) to most closely resemble the human pathology. Animals treated with LIP HM exhibited the highest antimelanoma effect resulting in a 6-, 5- and 4-fold reduction on tumor volume compared to negative control, Free HM and DTIC groups, respectively. No toxic side effects were detected. Overall, these results constitute another step forward in the validation of the antimelanoma activity of LIP HM, using a murine model that more accurately simulates the pathology that occurs in human patients.

BRAFV600E mutational status assessment in cutaneous melanocytic neoplasms in a group of the Egyptian population

BACKGROUND

Melanocytic neoplasms range from banal nevi to malignant melanomas. The genetic background has been extensively studied in the Caucasian population. BRAF mutations were reported among the early driver mutations in nevogenesis. Nevertheless, the pathogenesis in the Egyptian population has not been elucidated.

AIM AND METHODS

The present study was carried out to assess the sensitivity and specificity of immunohistochemistry (IHC) using the RM-08 clone in reference to allele-specific real-time PCR (CAST-PCR) for the detection of the BRAF ^V600E mutation in 50 formalin-fixed paraffin-embedded blocks of melanocytic neoplasms with prior bleaching using hydrogen peroxide in Tris-HCL and Bovine Serum Albumin respectively.

RESULTS

IHC staining was interpreted using staining reaction (positive versus negative) and staining pattern (negative and heterogeneous versus homogenous). Using the staining pattern, the specificity increased from 73.3 to 88.2%, the negative predictive value increased from 73.3 to 100%, the diagnostic accuracy increased from 71.4 to 90.48% and the overall accuracy increased from 69.9 to 77.3%. The sensitivity and positive predictive value remained unchanged. The K-agreement coefficient increased from 0.364 (fair agreement) to 0.741 (good agreement) and was statistically significant (p = 0.00). Next-generation sequencing was performed in 11 cases, 8 cases with IHC-positive and BRAF ^{wild type} in addition to 3 cases that failed PCR analysis and revealed no BRAF ^V600E. No statistically significant difference was found in the clinicopathological parameters between BRAF ^V600E and BRAF ^wild-type melanomas.

CONCLUSIONS

These findings suggest that IHC staining homogeneity may be more accurate in predicting BRAF ^V600E mutational status. However, IHC cannot replace molecular methods.

Dexamethasone and OLT1177 Cooperate in the Reduction of Melanoma Growth by Inhibiting STAT3 Functions

The NLRP3 inflammasome is a multimolecular complex that processes inactive IL-1β and IL-18 into proinflammatory cytokines. OLT1177 is an orally active small compound that specifically inhibits NLRP3. Here, B16F10 melanoma were implanted in mice and treated with OLT1177 as well as combined with the glucocorticoid dexamethasone. At sacrifice, OLT1177 treated mice had significantly smaller tumors compared to tumor-bearing mice treated with vehicle. However, the combined treatment of OLT1177 plus dexamethasone revealed a greater suppression of tumor growth. This reduction was accompanied by a downregulation of nuclear and mitochondrial STAT3-dependent gene transcription and by a significant reduction of STAT3 Y705 and S727 phosphorylations in the tumors. In vitro, the human melanoma cell line 1205Lu, stimulated with IL-1α, exhibited significantly lower levels of STAT3 Y705 phosphorylation by the combination treatment, thus affecting the nuclear functions of STAT3. In the same cells, STAT3 serine 727 phosphorylation was also lower, affecting the mitochondrial functions of STAT3. In addition, metabolic analyses revealed a marked reduction of ATP production rate and glycolytic reserve in cells treated with the combination of OLT1177 plus dexamethasone. These findings demonstrate that the combination of OLT1177 and dexamethasone reduces tumor growth by targeting nuclear as well as mitochondrial functions of STAT3.

A Unique Case of Intracranial Amelanotic Melanoma with BRAF V600E Mutation Successfully Treated via Molecular-targeted Therapy

Melanoma carries a high risk of brain metastasis. A small subset of metastatic melanomas, known as amelanotic melanomas, does not present black coloration, reflecting a lack of melanin pigmentation. Here, we report a case of B-Raf proto-oncogene (BRAF) V600E mutation associated with a metastatic brain tumor caused by the amelanotic melanoma. A 60-year-old man was transferred to our department following acute onsets of left upper limb paralysis and convulsion. In the brain imaging, multiple lesions in the right frontal lobe and left basal ganglia were detected, and the presence of an enlarged left axillary lymph node was revealed. Consequently, we removed the right frontal lesion and performed a biopsy of the left axillary lymph node. Histological analysis of both specimens indicated an amelanotic melanoma, and genetic testing revealed a BRAF V600E mutation. The residual intracranial lesions were treated with stereotactic radiotherapy and molecular-targeted therapy, with dabrafenib and trametinib as the systemic treatment. Based on the Response Evaluation Criteria in Solid Tumors, we determined that the patient achieved complete remission (CR) under uninterrupted molecular-targeted therapy over a period of 10 months. After the temporary withdrawal of dabrafenib and trametinib to avoid hepatic dysfunction, a new intracranial lesion appeared. CR of this lesion was achieved following reinstatement of the two drugs. These results suggest that, under limited conditions, molecular-targeted therapy can produce a sustained response against the intracranial metastasis of melanoma, and the therapy with reduced dose is still effective against a recurrent case after cessation of the therapy due to the toxicity.

Melanogenesis and the Targeted Therapy of Melanoma

Pigment production is a unique character of melanocytes. Numerous factors are linked with melanin production, including genetics, ultraviolet radiation (UVR) and inflammation. Understanding the mechanism of melanogenesis is crucial to identify new preventive and therapeutic strategies in the treatment of melanoma. Here, we reviewed the current available literatures on the mechanisms of melanogenesis, including the signaling pathways of UVR-induced pigment production, MC1R's central determinant roles and MITF as a master transcriptional regulator in melanogenesis. Moreover, we further highlighted the role of targeting BRAF, NRAS and MC1R in melanoma prevention and treatment. The combination therapeutics of immunotherapy and targeted kinase inhibitors are becoming the newest therapeutic option in advanced melanoma.

HSPB8 counteracts tumor activity of BRAF- and NRAS-mutant melanoma cells by modulation of RAS-prenylation and autophagy

Cutaneous melanoma is one of the most aggressive and lethal forms of skin cancer. Some specific driver mutations have been described in multiple oncogenes including BRAF and NRAS that are mutated in 60-70% and 15-20% of melanoma, respectively. The aim of this study was to evaluate the role of Small Heat Shock Protein B8 (HSPB8) on cell growth and migration of both BLM (BRAF^wt/NRAS^Q61R) and A375 (BRAF^V600E/NRAS^wt) human melanoma cell lines. HSPB8 is a member of the HSPB family of chaperones involved in protein quality control (PQC) system and contributes to chaperone assisted selective autophagy (CASA) as well as in the regulation of mitotic spindle. In cancer, HSPB8 has anti- or pro-tumoral action depending on tumor type. In melanoma cell lines characterized by low HSPB8 levels, we demonstrated that the restoration of HSPB8 expression causes cell growth arrest, reversion of EMT (Epithelial-Mesenchymal Transition)-like phenotype switching and antimigratory effect, independently from the cell mutational status. We demonstrated that HSPB8 regulates the levels of the active prenylated form of NRAS in NRAS-mutant and NRAS-wild-type melanoma cell lines. Consequently, the inhibition of NRAS impairs the activation of Akt/mTOR pathway inducing autophagy activation. Autophagy can play a dual role in regulating cell death and survival. We have therefore demonstrated that HSPB8-induced autophagy is a crucial event that counteracts cell growth in melanoma. Collectively, our results suggest that HSPB8 has an antitumoral action in melanoma cells characterized by BRAF and NRAS mutations.

Novel Biomarkers and Therapeutic Targets for Melanoma

Malignant melanoma is one of the most common cancers in the world. In the disease’s early stages, treatment involves surgery, in advanced stages however, treatment options were once scarce. There has been a paradigm shift in advanced melanoma treatment with the introduction of immunotherapy and targeted therapies. Understanding the molecular pathways and their pathologic counterparts helped identifying specific biomarkers that lead to the development of specific targeted therapies. In this review we briefly present some of these markers and their relevance to melanoma treatment.

Heterogeneity in Melanoma

There is growing evidence that tumour heterogeneity has an imperative role in cancer development, evolution and resistance to therapy. Continuing advancements in biomedical research enable tumour heterogeneity to be observed and studied more critically. As one of the most heterogeneous human cancers, melanoma displays a high level of biological complexity during disease progression. However, much is still unknown regarding melanoma tumour heterogeneity, as well as the role it plays in disease progression and treatment response. This review aims to provide a concise summary of the importance of tumour heterogeneity in melanoma.

dbEssLnc: A manually curated database of human and mouse essential lncRNA genes

Long non-coding RNAs (lncRNAs) play important roles in many biological processes. Knocking out or knocking down some lncRNAs will lead to lethality or infertility. These lncRNAs are called essential lncRNAs. Knowledges of essential lncRNAs are important in establishing minimal genomes of living cells, developing drug therapies and early diagnostic approaches for complex diseases. However, existing databases focus on collecting essential coding genes. Essential non-coding gene records are rare in existing databases. A comprehensive collection of essential non-coding genes, particularly essential lncRNA genes, is demanded. We manually curated 207 essential lncRNAs from literatures for establishing a database on essential lncRNAs, which is named as dbEssLnc (Database of essential lncRNAs). The dbEssLnc database has a web-based user-friendly interface for the users to browse, to search, to visualize and to blast search records in the database. The dbEssLnc database is freely accessible at https://esslnc.pufengdu.org. All data and source codes for mirroring the dbEssLnc database have been deposited in GitHub (https://github.com/yyZhang14/dbEssLnc).

Comparison of Two Rapid Assays for the Detection of BRAF V600 Mutations in Metastatic Melanoma including Positive Sentinel Lymph Nodes

Testing for the BRAF mutation is mandatory for the management of patients with locally advanced or metastatic melanoma. Molecular analysis based on DNA sequencing remains the gold-standard method for the screening of the different BRAF mutations. These methods must be rapid, sensitive, and specific enough to allow optimal therapeutic management in daily practice and also to include patients in clinical trials. Here, we compared the Idylla BRAF Mutation Test and the anti-BRAF V600E (clone VE1) immunohistochemistry (IHC) in 90 melanoma samples, with a focus on a challenging cohort of 32 positive sentinel lymph nodes. The BRAF status was assessed with both methods independently of the percentage of tumor cells. The concordance rate was calculated excluding both non-contributory analyses and BRAFV600K/R/M mutants due to the specific V600E-IHC test design. The incidence of the BRAFV600E mutation was 33% with both BRAF Idylla and BRAF IHC. The agreement rate was 91% (72/79). Although the agreement rate was high, we suggest that the use of IHC is more suitable for rapid BRAF testing on sentinel lymph node biopsies when associated with a low percentage and scattered tumor cells, which gave a high risk of non-contributory analysis and/or false negative results with the Idylla^TMBRAF Mutation Test.

Defining the Criteria for Reflex Testing for BRAF Mutations in Cutaneous Melanoma Patients

Targeted therapy has been developed through an in-depth understanding of molecular pathways involved in the pathogenesis of melanoma. Approximately ~50% of patients with melanoma have tumors that harbor a mutation of the BRAF oncogene. Certain clinical features have been identified in BRAF-mutated melanomas (primary lesions located on the trunk, diagnosed in patients <50, visibly pigmented tumors and, at times, with ulceration or specific dermatoscopic features). While BRAF mutation testing is recommended for stage III-IV melanoma, guidelines differ in recommending mutation testing in stage II melanoma patients. To fully benefit from these treatment options and avoid delays in therapy initiation, advanced melanoma patients harboring a BRAF mutation must be identified accurately and quickly. To achieve this, clear definition and implementation of BRAF reflex testing criteria/methods in melanoma should be established so that patients with advanced melanoma can arrive to their first medical oncology appointment with a known biomarker status. Reflex testing has proven effective for a variety of cancers in selecting therapies and driving other medical decisions. We overview the pathophysiology, clinical presentation of BRAF-mutated melanoma, current guidelines, and present recommendations on BRAF mutation testing. We propose that reflex BRAF testing should be performed for every melanoma patient with stages ≥IIB.