Transdermal Delivery of Ultradeformable Cationic Liposomes Complexed with miR211-5p (UCL-211) Stabilizes BRAFV600E+ Melanocytic Nevi.

Small non-coding RNAs (e.g. siRNA, miRNA) are involved in a variety of melanocyte-associated skin conditions and act as drivers for alterations in gene expression within melanocytes.

Genetic Silencing of AKT Induces Melanoma Cell Death via mTOR Suppression.

Aberrant activation of the PI3K-AKT pathway is common in many cancers, including melanoma, and AKT1, 2 and 3 (AKT1-3) are bona fide oncoprotein kinases with well-validated downstream effectors. However, efforts to pharmacologically inhibit AKT have proven to be largely ineffective. In this study, we observed paradoxical effects following either pharmacologic or genetic inhibition of AKT1-3 in melanoma cells.

Prior Exposure to Coxsackievirus A21 Does Not Mitigate Oncolytic Therapeutic Efficacy.

Oncolytic viruses (OVs) are being developed as a type of immunotherapy and have demonstrated durable tumor responses and clinical efficacy. One such OV, Coxsackievirus A21 (CVA21), exhibited therapeutic efficacy in early phase clinical trials, demonstrating the ability to infect and kill cancer cells and stimulate anti-tumor immune responses. However, one of the major concerns in using this common cold virus as a therapeutic is the potential for innate and adaptive immune responses to mitigate the benefits of viral infection, particularly in individuals that have been exposed to coxsackievirus prior to treatment.

BRAF inhibition in melanoma is associated with the dysregulation of histone methylation and histone methyltransferases.

The development of mutant BRAF inhibitors has improved the outcome for melanoma patients with BRAF mutations. Although the initial response to these inhibitors can be dramatic, sometimes resulting in complete tumor regression, the majority of melanomas become resistant. To study resistance to BRAF inhibition, we developed a novel mouse model of melanoma using a tetracycline/doxycycline-regulated system that permits control of mutant BRAF expression.

Aspirin Protects Melanocytes and Keratinocytes against UVB-Induced DNA Damage In Vivo.

UVR promotes skin cancer through multiple mechanisms, including induction of inflammation, oxidative stress, and DNA damage such as 8-oxoguanine and cyclobutane pyrimidine dimers. We investigated whether the anti-inflammatory activities of aspirin (acetylsalicylic acid [ASA]) could protect against UVB-induced DNA damage and skin carcinogenesis. ASA reduced UVB-induced 8-oxoguanine and cyclobutane pyrimidine dimers in Melan-A melanocytes and HaCaT keratinocytes.

ASA Suppresses PGE in Plasma and Melanocytic Nevi of Human Subjects at Increased Risk for Melanoma.

Potential anti-inflammatory and anticarcinogenic effects of aspirin (ASA) may be suitable for melanoma chemoprevention, but defining biomarkers in relevant target tissues is prerequisite to performing randomized controlled chemoprevention trials. We conducted open-label studies with ASA in 53 human subjects with melanocytic nevi at increased risk for melanoma. In a pilot study, 12 subjects received a single dose (325 mg) of ASA; metabolites salicylate, salicylurate, and gentisic acid were detected in plasma after 4-8 h, and prostaglandin E2 (PGE) was suppressed in both plasma and nevi for up to 24 h.

AKT1 Activates Focal Adhesion Kinase and Promotes Melanoma Brain Metastasis.

Alterations in the PI3K/AKT pathway occur in up to 70% of melanomas and are associated with disease progression. The three AKT paralogs are highly conserved but data suggest they have distinct functions. Activating mutations of AKT1 and AKT3 occur in human melanoma but their role in melanoma formation and metastasis remains unclear.

Aspirin Suppresses PGE and Activates AMP Kinase to Inhibit Melanoma Cell Motility, Pigmentation, and Selective Tumor Growth .

There are conflicting epidemiologic data on whether chronic aspirin (ASA) use may reduce melanoma risk in humans. Potential anticancer effects of ASA may be mediated by its ability to suppress prostaglandin E (PGE) production and activate 5'-adenosine monophosphate-activated protein kinase (AMPK). We investigated the inhibitory effects of ASA in a panel of melanoma and transformed melanocyte cell lines, and on tumor growth in a preclinical model.

Mutant IDH1 Promotes Glioma Formation In Vivo.

Isocitrate dehydrogenase 1 (IDH1) is the most commonly mutated gene in grade II-III glioma and secondary glioblastoma (GBM). A causal role for IDH1 in gliomagenesis has been proposed, but functional validation in vivo has not been demonstrated. In this study, we assessed the role of IDH1 in glioma development in the context of clinically relevant cooperating genetic alterations in vitro and in vivo.

Resistance mechanisms to genetic suppression of mutant NRAS in melanoma.

Targeted therapies have revolutionized cancer care, but the development of resistance remains a challenge in the clinic. To identify rational targets for combination strategies, we used an established melanoma mouse model and selected for resistant tumors following genetic suppression of NRAS expression. Complete tumor regression was observed in all mice, but 40% of tumors recurred.

In vitro visualization and characterization of wild type and mutant IDH homo- and heterodimers using Bimolecular Fluorescence Complementation.

Mutations in the metabolic enzyme (IDH) were recently found in ~80% of WHO grade II-III gliomas and secondary glioblastomas. These mutations reduce the enzyme's ability to convert isocitrate to α-ketoglutarate and, instead, confer a novel gain-of-function resulting in the conversion of α-ketoglutarate to 2-hydroxglutarate (2-HG). However, IDH mutations exist in a heterozygous state such that a functional wild type allele is retained.

A phase I study of intratumoral ipilimumab and interleukin-2 in patients with advanced melanoma.

Purpose: Intratumoral interleukin-2 (IL-2) is effective but does not generate systemic immunity. Intravenous ipilimumab produces durable clinical response in a minority of patients, with potentially severe toxicities. Circulating anti-tumor T cells activated by ipilimumab may differ greatly from tumor-infiltrating lymphocytes activated by intratumoral ipilimumab in phenotypes and functionality.

AKT1 Activation Promotes Development of Melanoma Metastases.

Metastases are the major cause of melanoma-related mortality. Previous studies implicating aberrant AKT signaling in human melanoma metastases led us to evaluate the effect of activated AKT1 expression in non-metastatic BRAF(V600E)/Cdkn2a(Null) mouse melanomas in vivo. Expression of activated AKT1 resulted in highly metastatic melanomas with lung and brain metastases in 67% and 17% of our mice, respectively.

Model of the TVA receptor determinants required for efficient infection by subgroup A avian sarcoma and leukosis viruses.

Unlabelled: The study of the interactions of subgroup A avian sarcoma and leucosis viruses [ASLV(A)] with the TVA receptor required to infect cells offers a powerful experimental model of retroviral entry. Several regions and specific residues in the TVA receptor have previously been identified to be critical determinants of the binding affinity with ASLV(A) envelope glycoproteins and to mediate efficient infection. Two homologs of the TVA receptor have been cloned: the original quail TVA receptor, which has been the basis for most of the initial characterization of the ASLV(A) TVA, and the chicken TVA receptor, which is 65% identical to the quail receptor overall but identical in the region thought to be critical for infection.

Akt signaling accelerates tumor recurrence following ras inhibition in the context of ink4a/arf loss.

Aberrant activation of the RAS signaling pathway contributes to nearly all human cancers, including gliomas. To determine the dependence of high-grade gliomas on this signaling pathway, we developed a doxycycline-regulated KRas glioma mouse model. Using this model we previously demonstrated that inhibition of KRas expression in gliomas induced by activated KRas and Akt results in complete tumor regression.

Ink4a/Arf loss promotes tumor recurrence following Ras inhibition.

Aberrant activation of rat sarcoma (Ras) signaling contributes to the development of a variety of human cancers, including gliomas. To determine the dependence of high-grade gliomas on continued Ras signaling, we developed a doxycycline-regulated Kirsten Ras (KRas) glioma mouse model. We previously demonstrated that KRas is required for the maintenance of glioblastoma multiforme tumors arising in the context of activated Akt signaling in vivo; inhibition of KRas expression resulted in apoptotic tumor regression and significantly increased survival.

Akt signaling is required for glioblastoma maintenance in vivo.

Glioblastoma multiforme (GBM) can be induced in mice through the combined expression of activated forms of KRas and Akt in glial progenitor cells. We have previously demonstrated that KRas is required for the maintenance of these tumors in vivo as inhibition of KRas expression resulted in apoptotic tumor regression and significantly increased survival. To determine the reliance of these tumors on Akt signaling in vivo, we generated a viral vector that allows the expression of Akt to be controlled post-delivery.

Targeted delivery of NRASQ61R and Cre-recombinase to post-natal melanocytes induces melanoma in Ink4a/Arflox/lox mice.

We have developed a somatic cell gene delivery mouse model of melanoma that allows for the rapid validation of genetic alterations identified in this disease. A major advantage of this system is the ability to model the multi-step process of carcinogenesis in immune-competent mice without the generation and cross breeding of multiple strains. We have used this model to evaluate the role of RAS isoforms in melanoma initiation in the context of conditional Ink4a/Arf loss.

Met amplification and tumor progression in Cdkn2a-deficient melanocytes.

While many genetic alterations have been identified in melanoma, the relevant molecular events that contribute to disease progression are poorly understood. Most primary human melanomas exhibit loss of expression of the CDKN2A locus in addition to activation of the canonical mitogen-activated protein kinase signaling pathway. In this study, we used a Cdkn2a-deficient mouse melanocyte cell line to screen for secondary genetic events in melanoma tumor progression.

Mitogen-activated protein kinase inhibition induces translocation of Bmf to promote apoptosis in melanoma.

Constitutive activation of the mitogen-activated protein kinase (MAPK) pathway is implicated in the development and progression of many human cancers, including melanoma. Mutually exclusive activating mutations in NRAS or BRAF have been identified in approximately 85% of melanomas, and components of this pathway have been developed as molecular targets for therapeutic intervention. We and others have shown that inhibition of this pathway with specific small molecule MAPK/extracellular signal-regulated kinase kinase (MEK) inhibitors induces a wide range of apoptotic responsiveness in human melanoma cells both in vitro and in vivo.

Inhibition of avian leukosis virus replication by vector-based RNA interference.

RNA interference (RNAi) has recently emerged as a promising antiviral technique in vertebrates. Although most studies have used exogenous short interfering RNAs (siRNAs) to inhibit viral replication, vectors expressing short hairpin RNAs (shRNA-mirs) in the context of a modified endogenous micro-RNA (miRNA) are more efficient and are practical for in vivo delivery. In this study, replication competent retroviral vectors were designed to deliver shRNA-mirs targeting subgroup B avian leukosis virus (ALV), the most effective of which reduced expression of protein targets by as much as 90% in cultured avian cells.

Mitogen-activated protein kinase pathway-dependent tumor-specific survival signaling in melanoma cells through inactivation of the proapoptotic protein bad.

Mitogen-activated protein kinase (MAPK) signaling regulates fundamental cellular functions including proliferation, differentiation, and survival. We have demonstrated previously that inhibiting MAPK signaling induces apoptosis in melanoma cells but not in normal melanocytes, suggesting that the MAPK pathway propagates essential survival signals in melanoma cells. Here, we report that the 90-kDa ribosomal S6 kinase (RSK), a downstream effector in the MAPK signaling cascade, phosphorylates and inactivates the Bcl-2 homology 3-only proapoptotic protein Bad, thereby mediating a MAPK-dependent tumor-specific survival signal in melanoma cells.