Skin Cancer In Mice Research Articles

Oral delivery of the non-β-blocking R-carvedilol enantiomer for skin cancer chemoprevention in SKH-1 mice

Abstract Purpose Skin cancer remains the most prevalent cancer worldwide with its incidence continuously rising. Previous studies have demonstrated the efficacy of the β-blocker carvedilol and its non-β-blocking enantiomer R-carvedilol in mitigating UV-induced skin carcinogenesis through topical application. The current study investigated whether orally administered R-carvedilol could prevent the development of skin cancer in SKH-1 mice. Methods Efficacy of orally delivered R-carvedilol was examined in SKH-1 mice exposed to repeated UV radiations for 25 weeks. Pharmacokinetic studies were conduced in mice to evaluate the drug levels in plasma and skin tissues. Pharmacodynamic studies were used to evaluate the effects of oral R-carvedilol and racemic carvedilol on mouse blood pressure. Results The findings revealed a statistical difference in tumor incidence between the group receiving R-carvedilol (20 mg/kg) and the UV-only control group (p = 0.00860), while lower doses of R-carvedilol (1.5 mg/kg and 5 mg/kg) did not exhibit a significant impact on tumor incidence. While tumor multiplicity varied significantly between groups (p = 0.005325), tumor volume analysis showed no statistical difference. Pharmacokinetic studies indicated that R-carvedilol accumulated in a dose-dependent manner within plasma and skin tissues. Notably, at a dosage of 32 mg/kg, oral R-carvedilol did not influence blood pressure, in contrast to carvedilol, highlighting its potential for chemoprevention with minimal cardiovascular side effects. Conclusions These data support oral administration of R-carvedilol as a viable strategy for the chemoprevention of skin cancer, given its efficacy and minimal impact on the cardiovascular system. Further studies determining the optimal doses and timing of drug treatment are warranted.

Single Nucleotide Polymorphisms on Toll-like Receptor-4 and the Risk of Developing Skin Cancer.

Exposure to solar ultraviolet (UV) radiation is an established risk factor for skin cancer. Toll-like receptor-4 (TLR4)-mediated immune dysregulation has emerged as a key mechanism for the detrimental effects of acute and chronic UV exposure and skin cancer in mice. Single nucleotide polymorphisms (SNPs) on the TLR4 gene have been reported to increase or decrease susceptibility to various cancers in other organs. There is limited information on TLR4 SNPs and susceptibility to human keratinocyte carcinomas. The study's objective is to test the association between TLR4 SNPs and the risk of developing keratinocyte carcinomas. Skin cancer patients and controls at the University of Alabama at Birmingham completed a cross-sectional survey on personal and family history of skin cancer as well as on sunscreen use and tanning proneness. Peripheral blood samples were obtained from participants, and DNA was extracted to genotype the TLR4 SNPs. Descriptive analytics were used to describe the cohort. Multivariable logistic regression models were used to assess the association between TLR4 SNPs and skin cancer risk. The sample consisted of a cohort of 93 skin cancer patients over the age of 50 and 94 controls; 33.3% of cases and 44.7% of controls were females; 12.9% of cases and 17% of controls had a TLR4 SNP. The most common SNP was D299G/T399I in 9.7% of skin cancer patients and 13.8% of controls. We did not find a statistically significant association between the D299G/T399I SNP and skin cancer (odds ratio (OR) = 0.34, 95% CI: 0.11, 1.07, p = 0.065) adjusting for age, sex, eye color, actinic keratosis, sunscreen use and reapplication, and family history of skin cancer. Based on our findings from our limited cohort of participants, we found some protective effect for the TLR4 SNP for skin cancer, which was not statistically significant. Validation of these findings in a larger cohort is warranted.

Prevention of supercritical carbon dioxide fluid extract from Chrysanthemum indicum Linnén on cutaneous squamous cell carcinomas progression following UV irradiation in mice.

Chrysanthemum indicum Linnén (C. indicum), a medicinal and food herb with various bioactive components, may be of beneficial use in cosmetics and the treatment of skin-related diseases. However, to date, few studies have been reported on its potential preventive and therapeutic effects on skin cancer. Therefore, the present study aimed to investigate the effect and potential mechanism of action of supercritical carbon dioxide extract from C. indicum (CISCFE) on UV-induced skin cancer in a mouse model. Kunming mice were allocated randomly to five treatment groups: Sham, model, low concentration CISCFE, high concentration CISCFE and positive control nicotinamide groups. The dorsal skin of mice was irradiated with UV light for 31 weeks. Histopathological changes, ELISA assays, immunohistochemical analysis and western blotting were performed to investigate the potential therapeutic effects of CISCFE. The results showed that CISCFE alleviated skin oxidative and inflammatory damage in a UV-induced mouse model of skin cancer. Moreover, CISCFE suppressed abnormal activation of proto-oncogene c-Myc and the overexpression of Ki-67 and VEGF, and increased expression of the anti-oncogene PTEN, thereby reducing abnormal proliferation of the epidermis and blood vessels. Additionally, CISCFE increased the protein expression levels of NAD-dependent protein deacetylase sirtuin-1 (SIRT1), Kelch-like ECH associated protein 1 (Keap1) and inhibited the expression of nuclear factor 2 erythroid 2-related factor 2 (Nrf2), phosphorylated (p)-p62 (Ser 349), p-p65 and acetyl-p65 proteins in a UV-induced skin cancer mouse model. In summary, CISCFE exhibited potent anti-skin cancer activity, which may be attributed its potential effects on the p62/Keap1-Nrf2 and SIRT1/NF-κB pathways.

Assessment of Anticancer Activity of Crude Ethanolic Extracts of Moringa Oleifera Pod and Leaves on 7,12 - Dimethylbenz Anthracene Induced Skin Cancer in Mice.

Background and Objective: Carcinoma of the skin is the commonest cancer in the world. This study aims to assess the anti-cancer effect of the ethanolic pod and leaf extracts of Moringa Oleifera on 7,12 - dimethylbenz anthracene (DMBA) induced skin carcinoma in mice. Methodology: Animals were divided into 6 groups of 5 each. 7,12 - dimethylbenz anthracene (DMBA) was used topically for four weeks to induce tumour. Group 1 received placebo, Group 2 - standard drug 5- Fluorouracil, Groups 3, 4 received pod extract and Groups 5,6 received leaf extract of Moringa Oleifera of concentration 500 and 1000mg/kg respectively for 3 weeks. Hematological and biochemical parameters such as Hemoglobin, RBC, WBC and platelet counts, SGOT and SGPT, blood urea nitrogen and serum creatinine were done before cancer induction and at the end of 7 weeks. Histopathological examination of the skin, liver and kidney were done at the end of 7 weeks. Results: There was reduction in tumor size in the Moringa Oleifera pod and leaf extract treated groups. Histopathology revealed infiltration of the cells with scarring of epidermis in the extract treated groups indicating the healing of tissues more pronounced at higher concentration. Control group showed atypical squamous cells whereas the standard drug treated group showed infiltration and scarring. Conclusion: This study exhibits a dose dependent anticancer effect of Moringa oleifera pod and leaf extracts in mice which was comparable with the standard drug 5-Fluorouracil.

Cancer-Preventive Activity of Argemone mexicana Linn Leaves and Its Effect on TNF-α and NF-κB Signalling

Skin cancer is the 5th most common cancer in Western countries with a surge in case occurrences making it a global burden on healthcare systems. The present study aims to evaluate the cancer-preventive activity of an ethanolic extract of Argemone mexicana Linn leaves (AML). The DMBA/TPA method was used to induce skin cancer in mice. Experimental animals were divided into three pretreatment groups of 100 mg/kg BW, 250 mg/kg BW, and 500 mg/kg BW of AML extract, and feeding was continued during the induction process. In the fourth group, 500 mg/kg BW AML extract treatment was started along with the cancer induction. The analyses were performed on the basis of the time period of in-tumour induction incidence, haematological parameters, histopathology and augmentation of TNF-α secretion and the NF-κB (p65 subunit) signalling pathway. The AML extract resisted and delayed tumour formation for up to 8 weeks in the 500 mg/kg BW pretreated group as compared to 4 weeks in the negative control group. The tumour burden varied in a dose-dependent manner in the different groups. On the 60th day, a significantly high burden (p < 0.001) was observed in the negative control group and the 100 mg/kg BW group. The study was validated by investigating the expression of TNF-α and the p65 subunit of the NF-κB signalling pathway, which were found to be reduced significantly in a dose-dependent manner and significantly reduced (p < 0.001) in the 500 mg/kg BW group as compared to negative control group. The 500 mg/kg BW pretreated group was found to have significant results in comparison to the 500 mg/kg BW post-treatment group. The study revealed the effective cancer preventive activity of Argemone mexicana Linn leaves (AML) in the mouse model and paved a pathway for molecular approaches which could be explored more in future studies.

Synthesis and characterization of piperic acid conjugates with homochiral and heterochiral dipeptides containing phenylalanine and their application in skin cancer

The current work demonstrates the synthesis and characterization of piperic acid conjugates with homochiral/heterochiral dipeptides containing phenylalanine as anti-skin cancer agents. The conjugates PA-DPhe-LPhe-OH, FC-1; PA-LPhe-DPhe-OH, FC-2; PA-DPhe-DPhe-OH, FC-3; and PA-DPhe-DPhe-OH, FC-4 were synthesized, characterized and assessed for cytotoxicity against melanoma cell lines of human and murine origin. Among all, PA-DPhe-DPhe-OH (FC-3) conjugate was identified as a potential cytotoxic lead against melanoma cells by delineating the anti-proliferative and anti-migratory potential together with its anti-inflammatory potential against pro-inflammatory interleukins (IL-1β, IL-6, and IL-8). Evidences from western blotting, fractionation, and immunocytochemistry experiments suggest that Stat-3 is a critical signaling molecule involved in the FC-3 mechanism of action. The results denote that FC-3 profoundly ablates Stat-3 expression, phosphorylation, and nuclear translocation. Stat-3 mRNA analysis revealed that FC-3 did not alter the transcription of Stat-3. However, in cells where proteasome mediated degradation was inhibited, FC-3 failed to check the Stat-3 expression implying that FC-3 augments the proteasomal degradation of Stat-3. Of note, FC-3 failed to reverse the IL-6 mediated hyperactivation of Stat-3 in A375 cells. Critically, in Stat-3 deficient cancer cells, the anti-clonogenic and anti-migratory potential of FC-3 was significantly subdued. Further, the in vivo efficacy of FC-3 was validated in the two-step (DMBA/TPA) chemically induced mouse skin cancer model. The FC-3-treated cohorts of mice unveiled a significant decrease in the cumulative number of tumors besides attenuation of tumor growth with respect to the vehicle-treated mice. Lastly, in corroboration with our in vitro findings, serum collected from mice groups at various intervals during the treatment regimen demonstrated decrement in IL-1β and IL-6 levels in FC-3 treated groups compared to the vehicle-treated group.

UVB Induced Skin Cancer Development in Experimental Mouse Model: A Review

Skin cancer is a widespread global issue, with ultraviolet (UV) radiation being a significant risk factor. Researchers often use the mouse skin cancer model to develop novel therapeutic chemoprevention strategies. This model involves exposing mice to UVB radiation to induce skin carcinogenesis. In this short communication, we found that 69.57% of studies used female SKH-1 hairless mice, 17.39% used BALB/c mice, 8.69% used Swiss albino mice, and 4.35% used HRS/J hairless mice. All studies used mice aged 5-8 weeks. Different models of mice were exposed to varying doses of UVB radiation. SKH-1 hairless mice received UVB radiation twice a week for 10-18 weeks, while Swiss albino mice were exposed to UVB radiation three times a week for 30 weeks. HRS/J hairless mice received UVB radiation five times a week for 15 weeks. BALB/c mice were treated with DMBA and exposed to UVB radiation for 10-16 weeks to induce skin tumors. However, using SKH-1 hairless mice is costly. In conclusion, we can suggest BALB/c mice treated with DMBA and exposed to UVB radiation three times a week for 16 weeks for UVB-induced skin cancer model, as it is more cost-effective than other hairless mouse models.

Local blockade of tacrolimus promotes T-cell-mediated tumor regression in systemically immunosuppressed hosts

BackgroundImmunosuppressive drugs such as tacrolimus have revolutionized our ability to transplant organs between individuals. Tacrolimus acts systemically to suppress the activity of T-cells within and around transplanted organs. However, tacrolimus...

SIRT6 pharmacological inhibition delays skin cancer progression in the squamous cell carcinoma

Sirtuin 6 (SIRT6) has a critical role in cutaneous Squamous Cell Carcinoma (cSCC): SIRT6 silencing in skin SCC cells has pro-differentiating effects and SIRT6 deletion abrogated DMBA-TPA-induced skin tumorigenesis in mice. On the other hand, SIRT6 acts as tumor suppressor in SCC by enhancing glycolysis in tumor propagating cells. Herein, pharmacological modulation of SIRT6 deacetylase activity was investigated in cSCC, with S6 (inhibitor) or MDL-800 (activator). In cSCC cells, S6 recreated the pro-differentiating effects of SIRT6 silencing, as the levels of Keratin 1, Keratin 10 and Loricrin were upregulated compared to controls. Next, the effects of SIRT6 pharmacological modulation were evaluated in a DMBA-TPA-induced skin cancer mouse model. Mice treated with the inhibitor S6 in a preventive approach, i.e. at the beginning of the promotion stage, presented reduced number and size of papillomas, compared to the controls. The epidermal hyperproliferation marker Keratin 6 and the cSCC marker Keratin 8 were less abundant when SIRT6 was inhibited. In S6-treated lesions, the Epithelial-Mesenchymal Transition (EMT) markers Zeb1 and Vimentin were less expressed compared to untreated lesions. In a therapeutic approach, i.e. treatment starting after papilloma appearance, the S6 group presented reduced papillomas (number and size), whereas MDL-800-treated mice displayed an opposite trend. In S6-treated lesions, Keratin 6 and Keratin 8 were less expressed, EMT was less advanced, with a higher E-cadherin/Vimentin ratio, indicating a delayed carcinogenesis when SIRT6 was inhibited. Our results confirm that SIRT6 plays a role in skin carcinogenesis and suggest SIRT6 pharmacological inhibition as a promising strategy in cSCC.

Combination oncolytic virus, radiation therapy, and immune checkpoint inhibitor treatment in anti-PD-1-refractory cancer

BackgroundImmunotherapies are becoming front-line treatments for many advanced cancers, and combinations of two or more therapies are beginning to be investigated. Based on their individual antitumor capabilities, we sought to...

10-Hydroxy Decanoic Acid-Based Vesicles as a Novel Topical Delivery System: Would It Be a Better Platform Than Conventional Oleic Acid Ufasomes for Skin Cancer Treatment?

10-hydroxy decanoic acid (HDA), a naturally derived fatty acid, was used for the preparation of novel fatty acid vesicles for comparison with oleic acid (OA) ufasomes. The vesicles were loaded with magnolol (Mag), a potential natural drug for skin cancer. Different formulations were prepared using the thin film hydration method and were statistically evaluated according to a Box-Behnken design in terms of particle size (PS), polydispersity index (PDI), zeta potential (ZP), and entrapment efficiency (EE). The ex vivo skin permeation and deposition were assessed for Mag skin delivery. In vivo, an assessment of the optimized formulae using 7,12-dimethylbenz[a]anthracene (DMBA)-induced skin cancer in mice was also conducted. The PS and ZP of the optimized OA vesicles were 358.9 ± 3.2 nm and -82.50 ± 7.13 mV compared to 191.9 ± 6.28 nm and -59.60 ± 3.07 mV for HDA vesicles, respectively. The EE was high (>78%) for both types of vesicles. Ex vivo permeation studies revealed enhanced Mag permeation from all optimized formulations compared to a drug suspension. Skin deposition demonstrated that HDA-based vesicles provided the highest drug retention. In vivo, studies confirmed the superiority of HDA-based formulations in attenuating DMBA-induced skin cancer during treatment and prophylactic studies.

Tumor preventive and antioxidant efficacy of chlorogenic acid-loaded chitosan nanoparticles in experimental skin carcinogenesis.

Oxidativestress, a pathological condition, contributes to the pathophysiology of a number of diseases including carcinogenesis. Numerous studies pointed out the disturbed antioxidants status and accumulation of oxidative stress markers in the carcinogenesis. The present study analyzed the anticancer efficacy of chlorogenic acid-loaded chitosan nanoparticles by utilizing the oxidative stress biomarkers as an endpoint in mice with skin cancer developed by 7,12-dimethylbenz(a)anthracene (DMBA). Oxidative stress markers' (lipidperoxidation by-products and antioxidants) levels or activitieswere measured using colorimetric assays. While mice exposed with DMBA alone showed a 100% tumor incidence, 0 and 50% tumor formation was seen in mice treated with DMBA + topical application of the nanoparticles and DMBA + orally administered nanoparticles, respectively. Also, the study noticed a 33% and 67% tumor incidence in mice treated with DMBA + topical application of free chlorogenic acidand DMBA + orally administered free chlorogenic acid, respectively. The present study noticed that the topical application of chlorogenic acid-loaded chitosan nanoparticles to DMBA-painted mice completely suppressed the tumor growth and restored the levels or activities of oxidative stress markers as compared to mice that received DMBA + oral administration of chlorogenic acid-loaded chitosan nanoparticles. The study observed that chlorogenic acid-loaded chitosan nanoparticles are more potent than free chlorogenic acid in preventing skin cancer in mice caused by DMBA. Thus, the present investigation explores the tumor-inhibiting efficacy of chlorogenic acid-loaded chitosan nanoparticles in experimental skin cancer, and the tumor preventive efficiency could be attributed to their antilipid peroxidative and antioxidant effects.

PHARMACOLOGICAL EVALUATION OF CINNAMALDEHYDE AGAINST DMBA-INDUCED SKIN CANCER IN ALBINO MICE

Objectives: The primary objective of this study was to assess the pharmacological activity of Cinnamaldehyde (CA) obtained from cinnamon bark in 7, 12-Dimethylbenz antharacene (DMBA)-induced skin cancer in albino mice and to assess the important cell antioxidant enzymes levels which play an important role in cancer. Methods: Cinnamon bark was collected to obtain CA phytochemical screening of extract was performed. Then pharmacological screening of extract was done in albino mice with skin cancer, after 12 weeks of observation, the animal was sacrificed, the skin samples were collected and various parameters were assessed and at the end histopathological studies were performed. Further statistical methods were applied to analyze the results. Results: The results revealed that CA produces significant increase in cell anti-oxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase content. It is also reported that it has inhibited the activity of lactate dehydrogenase and levels of lipid peroxidation at the same time which are responsible for cell damage. Conclusion: The present study shows that CA obtained from cinnamon bark consist of significant anti-cancer activity against DMBA-induced skin cancer in albino mice.

BOX-BEHNKEN DESIGN APPROACH TO DEVELOP NANO-VESICULAR HERBAL GEL FOR THE MANAGEMENT OF SKIN CANCER IN EXPERIMENTAL ANIMAL MODEL

Objective: To manage the increasing burden of skin cancer cases globally and to replace conventional invasive treatments and their side effects, the present study is aimed to develop a transfersomal herbal gel of Green Tea Catechins (GTC) extracted from indigenous green tea and evaluate it for in vivo management of skin cancer in an experimental animal model. Methods: GTC-loaded transfersomes (GTCTF) were prepared by the thin-film hydration method. After optimizing the GTCTFs using the Box-Behnken design, they were characterized for zeta potential, structure, in vitro drug release, and in vitro skin permeation. Carbopol 940 gel was developed for the topical delivery of GTCTF and characterized for pH, viscosity, spreadability and in vitro skin permeation. In vitro MTT assay and in vivo chemopreventive and anticancer efficacy of the GTCTF gel were evaluated in mice. Results: The GTCTF has shown a particle size of 151.4±1.9 nm, entrapment efficiency of 68.25±0.06 %, and drug loading of 10.41±0.02 %. The in vitro MTT assay in B16F10 melanoma cell lines showed promising anticancer efficacy of the GTCTF. GTCTF gel was found suitable for topical delivery with favorable pH, viscosity, spreadability, and permeability and effective in preventing and curing skin cancer in mice, with a significant reduction of tissue biochemical parameters like TNF-α, IL-1β, and IL-6. Conclusion: Collectively, successful prevention and curing of the induced skin cancer in the experimental animal model by the GTCTF gel have established a novel herbal nanomedicine approach for the management of skin cancer.

Beta Human Papillomavirus 8 E6 Induces Micronucleus Formation and Promotes Chromothripsis.

Cutaneous beta genus human papillomaviruses (β-HPVs) are suspected to promote the development of nonmelanoma skin cancer (NMSC) by destabilizing the host genome. Multiple studies have established the genome destabilizing capacities of β-HPV proteins E6 and E7 as a cofactor with UV. However, the E6 protein from β-HPV8 (HPV8 E6) induces tumors in mice without UV exposure. Here, we examined a UV-independent mechanism of HPV8 E6-induced genome destabilization. We showed that HPV8 E6 reduced the abundance of anaphase bridge resolving helicase, Bloom syndrome protein (BLM). The diminished BLM was associated with increased segregation errors and micronuclei. These HPV8 E6-induced micronuclei had disordered micronuclear envelopes but retained replication and transcription competence. HPV8 E6 decreased antiproliferative responses to micronuclei and time-lapse imaging revealed HPV8 E6 promoted cells with micronuclei to complete mitosis. Finally, whole-genome sequencing revealed that HPV8 E6 induced chromothripsis in nine chromosomes. These data provide insight into mechanisms by which HPV8 E6 induces genome instability independent of UV exposure. IMPORTANCE Some beta genus human papillomaviruses (β-HPVs) may promote skin carcinogenesis by inducing mutations in the host genome. Supporting this, the E6 protein from β-HPV8 (8 E6) promotes skin cancer in mice with or without UV exposure. Many mechanisms by which 8 E6 increases mutations caused by UV have been elucidated, but less is known about how 8 E6 induces mutations without UV. We address that knowledge gap by showing that 8 E6 causes mutations stemming from mitotic errors. Specifically, 8 E6 reduces the abundance of BLM, a helicase that resolves and prevents anaphase bridges. This hinders anaphase bridge resolution and increases their frequency. 8 E6 makes the micronuclei that can result from anaphase bridges more common. These micronuclei often have disrupted envelopes yet retain localization of nuclear-trafficked proteins. 8 E6 promotes the growth of cells with micronuclei and causes chromothripsis, a mutagenic process where hundreds to thousands of mutations occur in a chromosome.

Combined Kdm6a and Trp53 Deficiency Drives the Development of Squamous Cell Skin Cancer in Mice

Cutaneous squamous cell carcinoma (cSCC) has among the highest mutation burdens of all cancers, reflecting its pathogenic association with the mutagenic effects of UV light exposure. Although mutations in cancer-relevant genes such as TP53 and NOTCH1 are common in cSCC, they are also tolerated in normal skin and suggest that other events are required for transformation; it is not yet clear whether epigenetic regulators cooperate in the pathogenesis of cSCC. KDM6A encodes a histone H3K27me2/me3 demethylase that is frequently mutated in cSCC and other cancers. Previous sequencing studies indicate that roughly 7% of cSCC samples harbor KDM6A mutations, including frequent truncating mutations, suggesting a role for this gene as a tumor suppressor in cSCC. Mice with epidermal deficiency of both Kdm6a and Trp53 exhibited 100% penetrant, spontaneous cSCC development within a year, and exome sequencing of resulting tumors reveals recurrent mutations in Ncstn and Vcan. Four of 16 tumors exhibited deletions in large portions of chromosome 1 involving Ncstn, whereas another 25% of tumors harbored deletions in chromosome 19 involving Pten, implicating the loss of other tumor suppressors as cooperating events for combined KDM6A- and TRP53-dependent tumorigenesis. This study suggests that KDM6A acts as an important tumor suppressor for cSCC pathogenesis.

Imiquimod-induced ROS production causes lysosomal membrane permeabilization and activates caspase-8-mediated apoptosis in skin cancer cells

BackgroundLysosomal cell death is induced by lysosomal membrane permeabilization (LMP) and the subsequent release of lysosomal proteolytic enzymes, including cathepsins (CTSs), which results in mitochondrial dysfunction and apoptosis. Imiquimod (IMQ), a synthetic TLR7 ligand, has both antiviral and antitumor activity against various skin malignancies in clinical treatment. Previously, we demonstrated IMQ not only caused lysosomal dysfunction but also triggered lysosome biogenesis to achieve lysosomal adaptation in cancer cells. ObjectiveTo determine whether lysosomes are involved in IMQ-induced apoptosis. MethodsThe human skin cancer cell lines BCC, A375 and mouse melanoma cell line B16F10 were used in all experiments. Cell death was determined by the Cell Counting Kit-8 (CCK-8) assay and DNA content assay. Protein expression was determined by immunoblotting. Caspase-8 activity was assessed using a fluorescence caspase-8 kit and determined by flow cytometry and confocal microscopy. ResultsIMQ not only induced lysosome damage but also abrogated lysosome function in skin cancer cells. IMQ-induced caspase-8 activation contributed to the processes of lysosomal cell death. Moreover, the use of ROS scavengers significantly abolished caspase-8 activation and inhibited IMQ-induced LMP. Additionally, pharmacological inhibition of CTSD not only abrogated caspase-8 activation but also rescued IMQ-induced cell death. Finally, lysosome-alkalizing agents enhanced the cytotoxicity of IMQ in vitro and in vivo. ConclusionsIMQ-induced ROS accumulation promotes LMP, releases CTSs into the cytosol, stimulates caspase-8 activation and finally causes lysosomal cell death. Lysosomal cell death and the CTSD/caspase-8 axis may play a crucial role in IMQ-induced cell death.

104 Loss of Kdm6a and Trp53 drives the development of squamous cell skin cancer in mice

Cutaneous squamous cell carcinoma (cSCC) has among the highest mutation burdens of all cancers, reflecting its association with the mutagenic effects of ultraviolet light. Though mutations in established, cancer-relevant genes like TP53 and NOTCH1 are prevalent in cSCC, they are tolerated in clinically normal skin and are insufficient to cause skin cancer. Whether epigenetic regulators cooperate in the development of squamous cell carcinoma is just starting to be defined. KDM6A encodes a histone H3K27me2/me3 demethylase that is frequently mutated in cSCC and other cancers.

Formulation and Characterization of Metformin-Loaded Ethosomes for Topical Application to Experimentally Induced Skin Cancer in Mice.

To achieve the best treatment of skin cancer, drug penetration inside the deepest layers of the skin is an important scientific interest. We designed an ethosome formulation that serves as a carrier for metformin and measured the in vitro skin permeation. We also aimed to measure the antitumor activity of the optimal ethosomal preparation when applied topically to chemically induced skin cancer in mice. We utilized a statistical Box–Behnken experimental design and applied three variables at three levels: lecithin concentration, cholesterol concentration and a mixture of ethanol and isopropyl alcohol concentrations. All formulations were prepared to calculate the entrapment efficiency %, zeta potential, size of the vesicles and drug release % after 1, 2, 4, 8 and 24 h. The size of the vesicles for the formulations was between 124 ± 14.2 nm and 560 ± 127 nm, while the entrapment efficiency was between 97.8 ± 0.23% and 99.4 ± 0.24%, and the drug release % after 8 h was between 38 ± 0.82% and 66 ± 0.52%. All formulations were introduced into the Box–Behnken software, which selected three formulations; then, one was assigned as an optimal formula. The in vivo antitumor activity of metformin-loaded ethosomal gel on skin cancer was greater than the antitumor activity of the gel preparation containing free metformin. Lower lecithin, high ethanol and isopropyl alcohol and moderate cholesterol contents improved the permeation rate. Overall, we can conclude that metformin-loaded ethosomes are a promising remedy for treating skin cancers, and more studies are warranted to approve this activity in other animal models of skin cancers.

Mutagenicity and carcinogenicity of combustion emissions are impacted more by combustor technology than by fuel composition: A brief review.

Studies during the past 50 years have characterized the carcinogenicity and mutagenicity of extractable organic material (EOM) of particulate matter (PM) in ambient air and from combustion emissions. We have summarized conclusions from these studies and present data supporting those conclusions for 50 combustion emissions, including carcinogenic potencies on mouse skin (papillomas/mouse/mg EOM), mutagenic potencies (revertants/μg EOM) in the Salmonella (Ames) mutagenicity assay, and mutagenicity emission factors (revertants/kg fuel or revertants/MJthermal) in Salmonella. Mutagenic potencies of EOM from PM in ambient air and combustion emissions span 1–2 orders of magnitude, respectively. In contrast, the revertants/m3 span >5 orders of magnitude due to variable PM concentrations in ambient air. Carcinogenic potencies of EOM from combustion emissions on mouse skin and EOM‐associated human lung cancer risk from those emissions both span ~3 orders of magnitude and are highly associated. The ubiquitous presence of polycyclic aromatic hydrocarbons (PAHs), nitroarenes, and aromatic amines results in mutagenic and carcinogenic potencies of PM that span only 1–3 orders of magnitude; most PM induces primarily G to T mutations. Mutagenicity emission factors of combustion emissions span 3–5 orders of magnitude and correlate with PAH emission factors (r > 0.9). Mutagenicity emission factors were largely a function of how material was burned (highly efficient modern combustors versus open burning) rather than what materials were burned. Combustion systems that minimize kinetic and mass‐transfer limitations and promote complete oxidation also minimize the mutagenicity of their emissions. This fundamental engineering principle can inform environmental and public health assessments of combustion emissions.