Mohammed Dany

Ceramide induced mitophagy and tumor suppression.

Sphingolipids are bioactive lipid effectors, which are involved in the regulation of various cellular signaling pathways. Sphingolipids play essential roles in controlling cell inflammation, proliferation, death, migration, senescence, metastasis and autophagy. Alterations in sphingolipid metabolism have been also implicated in many human cancers. Macroautophagy (referred to here as autophagy) is a form of nonselective sequestering of cytosolic materials by double membrane structures, autophagosomes, which can be either protective or lethal for cells. Ceramide, a central molecule of sphingolipid metabolism is involved in the regulation of autophagy at various levels, including the induction of lethal mitophagy, a selective autophagy process to target and eliminate damaged mitochondria. In this review, we focused on recent studies with regard to the regulation of autophagy, in particular lethal mitophagy, by ceramide, and aimed at providing discussion points for various context-dependent roles and mechanisms of action of ceramide in controlling mitophagy.

Advances in immunotherapy for melanoma management

ABSTRACT Melanoma remains a leading cause of death among young adults. Evidence that melanoma tumor cells are highly immunogenic and a better understanding of T-cell immune checkpoints have changed the therapeutic approach to advanced melanoma. Instead of targeting the tumor directly, immunotherapy targets and activates the immune response using checkpoint inhibitors, monoclonal antibodies, vaccines, and adoptive T cell therapy. This review focuses on the immune signaling and biological mechanisms of action of recent immune-based melanoma therapies as well as their clinical benefits.

Moringa oleifera's Nutritious Aqueous Leaf Extract Has Anticancerous Effects by Compromising Mitochondrial Viability in an ROS-Dependent Manner

Introduction: Moringa oleifera (MO) is an important dietary component for many populations in West Africa and the Indian subcontinent. In addition to its highly nutritious value, almost all parts of this plant have been widely used in folk medicine in curing infectious, cardiovascular, gastrointestinal, hepatic, and other diseases. Evidence-based research supported its versatile medicinal properties; however, more rigorous research is required to establish it in cancer therapy. As such, in this study we aim to investigate the in vitro anticancerous effect of Moringa oleiferas aqueous leaf extract. Methods: Moringa extract was prepared by soaking pulverized leaves in hot water mimicking the peoples mode of the leaf drink preparation. Several assays were used to study the effect of different percentage concentrations of the extract on viability of A549 cells; levels of adenosine triphosphate (ATP), reactive oxygen species (ROS), and glutathione (GSH) generated; as well as percentage of lactate dehydrogenase (LDH) released at different time points. In addition to mitochondrial membrane potential, apoptotic events were assessed using western blotting for apoptotic markers and immunoflourescent flourescent labeled inhibitor of caspases (FLICA) assay. Results: MO extract treatment resulted in a significant decrease in mitochondrial membrane potential (1 hour) and ATP levels (3 hours), followed by an increase in (6 hours) ROS, caspase activation, proapoptotic proteins expression (p53, SMAC/Diablo, AIF), and PARP-1 cleavage. This eventually resulted in decreased GSH levels and a decrease in viability. The cytotoxic effect was prevented upon pretreatment with antioxidant N-acetyl-cysteine. MO decreased as well the viability of HepG2, CaCo2, Jurkat, and HEK293 cells. Conclusion: Our findings identify a plant extract with an anticancerous effect on cancer cell lines. MO extract exerts its cytotoxic effect in A549 cancer cells by affecting mitochondrial viability and inducing apoptosis in an ROS-dependent manner.

Ceramide synthesis regulates T cell activity and GVHD development

Allogeneic hematopoietic cell transplantation (allo-HCT) is an effective immunotherapy for a variety of hematologic malignances, yet its efficacy is impeded by the development of graft-versus-host disease (GVHD). GVHD is characterized by activation, expansion, cytokine production, and migration of alloreactive donor T cells. Hence, strategies to limit GVHD are highly desirable. Ceramides are known to contribute to inflammation and autoimmunity. However, their involvement in T-cell responses to alloantigens is undefined. In the current study, we specifically characterized the role of ceramide synthase 6 (CerS6) after allo-HCT using genetic and pharmacologic approaches. We found that CerS6 was required for optimal T cell activation, proliferation, and cytokine production in response to alloantigen and for subsequent induction of GVHD. However, CerS6 was partially dispensable for the T cell-mediated antileukemia effect. At the molecular level, CerS6 was required for efficient TCR signal transduction, including tyrosine phosphorylation, ZAP-70 activation, and PKCθ/TCR colocalization. Impaired generation of C16-ceramide was responsible for diminished allogeneic T cell responses. Furthermore, targeting CerS6 using a specific inhibitor significantly reduced T cell activation in mouse and human T cells in vitro. Our study provides a rationale for targeting CerS6 to control GVHD, which would enhance the efficacy of allo-HCT as an immunotherapy for hematologic malignancies in the clinic.

HPV/E7 induces chemotherapy‐mediated tumor suppression by ceramide‐dependent mitophagy

Human papillomavirus (HPV) infection is linked to improved survival in response to chemo‐radiotherapy for patients with oropharynx head and neck squamous cell carcinoma (HNSCC). However, mechanisms involved in increased HNSCC cell death by HPV signaling in response to therapy are largely unknown. Here, using molecular, pharmacologic and genetic tools, we show that HPV early protein 7 (E7) enhances ceramide‐mediated lethal mitophagy in response to chemotherapy‐induced cellular stress in HPV‐positive HNSCC cells by selectively targeting retinoblastoma protein (RB). Inhibition of RB by HPV‐E7 relieves E2F5, which then associates with DRP1, providing a scaffolding platform for Drp1 activation and mitochondrial translocation, leading to mitochondrial fission and increased lethal mitophagy. Ectopic expression of a constitutively active mutant RB, which is not inhibited by HPV‐E7, attenuated ceramide‐dependent mitophagy and cell death in HPV(+) HNSCC cells. Moreover, mutation of E2F5 to prevent Drp1 activation inhibited mitophagy in HPV(+) cells. Activation of Drp1 with E2F5‐mimetic peptide for inducing Drp1 mitochondrial localization enhanced ceramide‐mediated mitophagy and led to tumor suppression in HPV‐negative HNSCC‐derived xenograft tumors in response to cisplatin in SCID mice.

TGF-β receptor I/II trafficking and signaling at primary cilia are inhibited by ceramide to attenuate cell migration and tumor metastasis

Ceramide forms complexes with Smad7 to inhibit cell migration–associated TGF-β–sonic hedgehog signaling in primary cilia. The good side of ceramides Ceramides are lipids that contribute to various cellular structures and functions. In the context of cancer, some ceramides, and the enzymes that produce them, contribute to tumor growth because they provide a critical component of the plasma membrane, enabling cells to divide. However, Gencer et al. found that certain long-chain ceramides synthesized by the enzyme CerS4 play a critical tumor suppressor role. C18- to C20-ceramides mediated the interaction between an inhibitory Smad protein and a TGF-β receptor complex, thus blocking subsequent cross-talk activation of the sonic hedgehog (Shh) pathway in tumor cells’ primary cilia, a region of the cell that coordinates motility. Depleting CerS4 in tumor cells increased the incidence of distant metastases from mammary tumors in mice. The disruption of TGF-β–Shh cross-talk by CerS4 may also prevent the development of the hair loss disorder alopecia. Both the TGF-β and Shh pathways are challenging to target pharmacologically; these findings suggest that some ceramides may have therapeutic potential against these pathways in various disorders. Signaling by the transforming growth factor–β (TGF-β) receptors I and II (TβRI/II) and the primary cilia-localized sonic hedgehog (Shh) pathway promote cell migration and, consequently, tumor metastasis. In contrast, the sphingolipid ceramide inhibits cell proliferation and tumor metastasis. We investigated whether ceramide metabolism inhibited TβRI/II trafficking to primary cilia to attenuate cross-talk between TβRI/II and the Shh pathway. We found that ceramide synthase 4 (CerS4)–generated ceramide stabilized the association between TβRI and the inhibitory factor Smad7, which limited the trafficking of TβRI/II to primary cilia. Expression of a mutant TβRI that signals but does not interact with Smad7 prevented the CerS4-mediated inhibition of migration in various cancer cells. Genetic deletion or knockdown of CerS4 prevented the formation of the Smad7-TβRI inhibitory complex and increased the association between TβRI and the transporter Arl6 through a previously unknown cilia-targeting signal (Ala31Thr32Ala33Leu34Gln35) in TβRI. Mutating the cilia-targeting signal abolished the trafficking of TβRI to the primary cilia. Localization of TβRI to primary cilia activated a key mediator of Shh signaling, Smoothened (Smo), which stimulated cellular migration and invasion. TβRI-Smo cross-talk at the cilia in CerS4-deficient 4T1 mammary cancer cells induced liver metastasis from orthotopic allografts in both wild-type and CerS4-deficient mice, which was prevented by overexpression of Smad7 or knockdown of intraflagellar transport protein 88 (IFT88). Overall, these data reveal a ceramide-dependent mechanism that suppresses cell migration and invasion by restricting TβRI/II-Shh signaling selectively at the plasma membrane of the primary cilium.

Gene expression of sphingolipid metabolism pathways is altered in hidradenitis suppurativa

Background Hidradenitis suppurativa (HS) is a debilitating skin disease characterized by painful recurrent nodules and abscesses caused by chronic inflammation. Early events in the development of HS are believed to occur in the folliculopilosebaceous unit; however, the signaling pathways behind this mechanism are unknown. Sphingolipids, such as ceramide, are essential components of the skin and appendages and have important structural and signaling roles. Objective We sought to explore whether the gene expression of enzymes involved in sphingolipid metabolic pathways is altered in HS. Methods A microarray data set including 30 samples was used to compare the expression of sphingolipid‐related enzymes in inflammatory skin lesions from HS patients (n = 17) with the expression in clinically healthy skin tissue (n = 13). Differential expression of sphingolipid metabolism–related genes was analyzed using Gene Expression Omnibus 2R. Results HS lesional skin samples have significantly decreased expression of enzymes generating ceramide and sphingomyelin, increased expression of enzymes catabolizing ceramide to sphingosine, and increased expression of enzymes converting ceramide to galactosylceramide and gangliosides. Limitations Limitations of this study include assessing the expression of sphingolipid‐related enzymes without assessing the levels of the related sphingolipids. Conclusion Our study suggests that sphingolipid metabolism is altered in HS lesional skin compared with normal skin.

Behavioral Perceptions of Oakland University Female College Students towards Human Papillomavirus Vaccination

Human Papillomavirus (HPV) vaccination decreases the risk for cervical cancer. However, the uptake of HPV vaccine remains low when compared with other recommended vaccines. This study evaluates the knowledge and attitudes towards HPV infection and vaccination, and the readiness for the uptake of HPV vaccine amongst female students attending Oakland University (OU) in Michigan, United States. This is a cross-sectional study targeting a randomized sample of a 1000 female OU students using an online questionnaire. The data were statistically analyzed using SPSS software. A total of 192 female students, with the mean age of 24 years completed the survey. The majority of participants had previous sexual experience with occasional use of contraceptives (78.1%), were non-smokers (92.7%), and non-alcohol drinkers (54.2%). The participants had a mean knowledge score of 53.0% with a standard error of 2.3% translating to a moderately informed population. The majority agreed that HPV is life threatening (79%), the vaccine prevents cervical cancer (62%), and that side effects would not deter them from vaccination (63%). Although two thirds (67%) believed that, based on sexual practices in the United States, female college students in Michigan have a higher chance of contracting HPV, about 50% did not believe they themselves were at risk. Higher knowledge correlated with increased recommendation for the vaccine (correlation-factor 0.20, p = 0.005). Results suggested that the best predictor for improvement of vaccination was the awareness level and health education. This indicates a need for an educational intervention to raise awareness, increase HPV vaccine uptake, and decrease the incidence of cervical cancer.

Sphingosine metabolism as a therapeutic target in cutaneous melanoma

Melanoma is by far the most aggressive type of skin cancer with a poor prognosis in its advanced stages. Understanding the mechanisms involved in melanoma pathogenesis, response, and resistance to treatment has gained a lot of attention worldwide. Recently, the role of sphingolipid metabolism has been studied in cutaneous melanoma. Sphingolipids are bioactive lipid effector molecules involved in the regulation of various cellular signaling pathways such as inflammation, cancer cell proliferation, death, senescence, and metastasis. Recent studies suggest that sphingolipid metabolism impacts melanoma pathogenesis and is a potential therapeutic target. This review focuses on defining the role of sphingolipid metabolism in melanoma carcinogenesis, discussing sphingolipid-based therapeutic approaches, and highlighting the areas that require more extensive research.

T helper (Th)17 radiation-induced hidradenitis suppurativa

To the Editor: We read with interest the case report describing the development of hidradenitis suppurativa (HS) lesions after radiation treatment in a patient with uterine adenocarcinoma. The authors provided several thoughts on the possible mechanism behind radiation-induced HS. The purpose of this letter is to provide additional insight about the likely immunologic mechanisms behind radiationinduced HS. The reported case is an example of an abscopal-like effect sharing adenocarcinoma antigens to antigens of apocrine glands of the groin. Abscopal effect is an immune-mediated phenomenon that has been heavily discussed in metastatic melanoma, whereby there is regression of nonirradiated metastatic lesions after irradiation of a distant melanoma tumor location. Abscopal effects were also recently reported in advanced melanoma patients after immunotherapy, highlighting the therapeutic implications of this phenomenon. As the authors point out, apoptosis can be induced by irradiation. It is likely that apoptotic uterine adenocarcinoma cells result in T-cell cross priming after radiation and activate Th17 subset. A recent article points out that Th17 is an important subset in the immunopathogenesis of HS, like it is in psoriasis. This case and the article by Matusiak et al make a strong case that HS, like psoriasis, is an autoimmune disease with Th17 and the attendant polymorphonuclear leukocytes involved. Oppman et al identified the p19 third subunit of interleukin (IL)-12, and designated it as IL-23. This finding predicted the potential for treating psoriasis with antieIL-12 ustekinumab and antieIL-23 (guselkumab). This case of radiation-induced HS is likely to predict a positive outcome with clinical trials for HS with ustekinumab (IL-12 antagonist), secukinumab (IL-17 antagonist), and guselkumab (IL-23 antagonist). Mohammed Dany, PhD, Tina Rendini, and William Levis, MD