Targeting the Melanocortin 1 Receptor in Melanoma: Biological Activity of α-MSH-Peptide Conjugates

Malignant melanoma is one of the most aggressive and resistant tumor types, with high metastatic properties. Because of the lack of suitable chemotherapeutic agents for treatment, the 5-year survival rate of melanoma patients with regional and distant metastases is lower than 10%. Targeted tumor therapy that provides several promising results might be a good option for the treatment of malignant melanomas. Our goal was to develop novel melanoma-specific peptide-drug conjugates for targeted tumor therapy. Melanocortin-1-receptor (MC1R) is a cell surface receptor responsible for melanogenesis and it is overexpressed on the surface of melanoma cells, providing a good target. Its native ligand, α-MSH (α-melanocyte-stimulating hormone) peptide, or its derivatives, might be potential homing devices for this purpose. Therefore, we prepared three α-MSH derivative-daunomycin (Dau) conjugates and their in vitro and in vivo antitumor activities were compared. Dau has an autofluorescence property; therefore, it is suitable for preparing conjugates for in vitro (e.g., cellular uptake) and in vivo experiments. Dau was attached to the peptides via a non-cleavable oxime linkage that was applied efficiently in our previous experiments, resulting in conjugates with high tumor growth inhibition activity. The results indicated that the most promising conjugate was the compound in which Dau was connected to the side chain of Lys (Ac-SYSNleEHFRWGK(Dau=Aoa)PV-NH2). The highest cellular uptake by melanoma cells was demonstrated using the compound, with the highest tumor growth inhibition detected both on mouse (38.6% on B16) and human uveal melanoma (55% on OMC-1) cells. The effect of the compound was more pronounced than that of the free drug.

Shikonin Causes an Apoptotic Effect on Human Kidney Cancer Cells through Ras/MAPK and PI3K/AKT Pathways

(1) Background: Shikonin, the main ingredient in Chinese herbal medicine, is described as a novel angiogenesis inhibitor, and its anticancer effects have already been studied. Shikonin and its derivatives induce apoptosis and suppress metastasis, which further enhance the effectiveness of chemotherapy. However, their mechanism of function has not been completely elucidated on human renal cancer cells. (2) Methods: In our study, CAKI-2 and A-498 cells were treated with increasing concentrations (2.5-40 µM) of shikonin, when colony formation ability and cytotoxic activity were tested. The changes in the expression of the main targets of apoptotic pathways were measured by RT-qPCR and Western blot. The intracellular levels of miR-21 and miR-155 were quantified by RT-qPCR. (3) Results: Shikonin exerted a dose-dependent effect on the proliferation of the cell lines examined. In 5 µM concentration of shikonin in vitro elevated caspase-3 and -7 levels, the proteins of the Ras/MAPK and PI3K/AKT pathways were activated. However, no significant changes were detected in the miR-21 and miR-155 expressions. (4) Conclusions: Our findings indicated that shikonin causes apoptosis of renal cancer cells by activating the Ras/MAPK and PI3K/AKT pathways. These effects of shikonin on renal cancer cells may bear important potential therapeutic implications for the treatment of renal cancer.

Assessment of Visual Quality Improvement as a Result of Spectacle Personalization

Personalized spectacles customized according to an individual's facial anatomy were developed to provide enhanced visual performance and overall comfort when compared to standard spectacles. In this comparative crossover trial, each subject was randomly assigned to wear either personalized spectacles or standard spectacles for two weeks and then tried the second pair for another two weeks. Visual acuity and reading speed were measured, and visual quality and comfort were assessed using specific questionnaires. The correlation of the wearing parameters with the subjects' satisfaction was calculated. According to our results, the subjects wearing personalized glasses reported significantly less experience of swaying and significantly higher overall satisfaction compared to those wearing the control spectacles. At the end of the study, 62% of subjects preferred the personalized spectacles, and visual quality was the primary reason for their spectacle preference followed by wearing comfort. The difference from the ideal cornea-vertex distance was significantly lower when wearing the personalized spectacles compared to the control frames. In addition, the absolute value of the difference from the ideal cornea-vertex distance was significantly correlated with patient satisfaction. These results suggest that personalized spectacles, customized according to an individual's facial anatomy for the ideal wearing parameters, result in both visual and comfort advantages for wearers.

Potential Role of VHL, PTEN, and BAP1 Mutations in Renal Tumors

The genetic profiling of renal tumors has revealed genomic regions commonly affected by structural changes and a general genetic heterogeneity. The VHL, PTEN, and BAP1 genes are often mutated in renal tumors. The frequency and clinical relevance of these mutations in renal tumors are still being researched. In our study, we investigated VHL, PTEN, and BAP1 genes and the sequencing of 24 samples of patients with renal tumors, revealing that VHL was mutated at a noticeable frequency (25%). Six of the investigated samples showed mutations, and one genetic polymorphism (rs779805) was detected in both heterozygote and homozygote forms. PTEN gene mutation was observed in only one sample, and one specimen showed genetic polymorphism. In the case of the BAP1 gene, all of the samples were wild types. Interestingly, VHL mutation was detected in two female patients diagnosed with AML and in one with oncocytoma. We assume that VHL or PTEN mutations may contribute to the development of human renal cancer. However, the overall mutation rate was low in all specimens investigated, and the development and prognosis of the disease were not exclusively associated with these types of genetic alterations.

Development and Biochemical Characterization of Self-Immolative Linker Containing GnRH-III-Drug Conjugates

The human gonadotropin releasing hormone (GnRH-I) and its sea lamprey analogue GnRH-III specifically bind to GnRH receptors on cancer cells and can be used as targeting moieties for targeted tumor therapy. Considering that the selective release of drugs in cancer cells is of high relevance, we were encouraged to develop cleavable, self-immolative GnRH-III-drug conjugates which consist of a p-aminobenzyloxycarbonlyl (PABC) spacer between a cathepsin B-cleavable dipeptide (Val-Ala, Val-Cit) and the classical anticancer drugs daunorubicin (Dau) and paclitaxel (PTX). Alongside these compounds, non-cleavable GnRH-III-drug conjugates were also synthesized, and all compounds were analyzed for their antiproliferative activity. The cleavable GnRH-III bioconjugates revealed a growth inhibitory effect on GnRH receptor-expressing A2780 ovarian cancer cells, while their activity was reduced on Panc-1 pancreatic cancer cells exhibiting a lower GnRH receptor level. Moreover, the antiproliferative activity of the non-cleavable counterparts was strongly reduced. Additionally, the efficient cleavage of the Val-Ala linker and the subsequent release of the drugs could be verified by lysosomal degradation studies, while radioligand binding studies ensured that the GnRH-III-drug conjugates bound to the GnRH receptor with high affinity. Our results underline the high value of GnRH-III-based homing devices and the application of cathepsin B-cleavable linker systems for the development of small molecule drug conjugates (SMDCs).

Accuracy of machine learning classifiers using bilateral data from a Scheimpflug camera for identifying eyes with preclinical signs of keratoconus

PURPOSE

To describe the topographic and tomographic characteristics of normal fellow eyes of unilateral keratoconus cases and to evaluate the accuracy of machine learning classifiers in discriminating healthy corneas from the normal fellow corneas.

SETTING

Department of Ophthalmology, Semmelweis University, Budapest, Hungary.

DESIGN

Retrospective case-control study.

METHODS

Patients with bilateral keratoconus (keratoconus group), clinically and according to the keratoconus indices of the Pentacam HR Scheimpflug camera; normal fellow eyes of patients with unilateral keratoconus (fellow-eye group); and eyes of refractive surgery candidates (control group) were compared. Tomographic data, topographic data, and keratoconus indices were measured in both eyes using the Scheimpflug camera. Receiver operating characteristic (ROC) analysis was used to assess the performance of automated classifiers trained on bilateral data as well as individual parameters to discriminate fellow eyes of patients with keratoconus from control eyes.

RESULTS

Keratometry, elevation, and keratoconus indices values were significantly higher and pachymetry values were significantly lower in keratoconus eyes than in fellow eyes of unilateral keratoconus cases (P < .001). These fellow eyes had significantly higher keratometry, elevation, and keratoconus index values and significantly lower pachymetry values than control eyes (P < .001). Automated classifiers trained on bilateral data of index of height decentration had higher accuracy than the unilateral single parameter in discriminating fellow eyes of patients with keratoconus from control eyes (area under ROC 0.96 versus 0.88).

CONCLUSION

Automatic classifiers trained on bilateral data were better than single parameters in discriminating fellow eyes of patients with unilateral keratoconus with preclinical signs of keratoconus from normal eyes.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Sensitivity of Melanoma Cells to EGFR and FGFR Activation but Not Inhibition is Influenced by Oncogenic BRAF and NRAS Mutations

BRAF and NRAS are the two most frequent oncogenic driver mutations in melanoma and are pivotal components of both the EGF and FGF signaling network. Accordingly, we investigated the effect of BRAF and NRAS oncogenic mutation on the response to the stimulation and inhibition of epidermal and fibroblast growth factor receptors in melanoma cells. In the three BRAF mutant, two NRAS mutant and two double wild-type cell lines growth factor receptor expression had been verified by qRT-PCR. Cell proliferation and migration were determined by the analysis of 3-days-long time-lapse videomicroscopic recordings. Of note, a more profound response was found in motility as compared to proliferation and double wild-type cells displayed a higher sensitivity to EGF and FGF2 treatment when compared to mutant cells. Both baseline and induced activation of the growth factor signaling was assessed by immunoblot analysis of the phosphorylation of the downstream effectors Erk1/2. Low baseline and higher inducibility of the signaling pathway was characteristic in double wild-type cells. In contrast, oncogenic BRAF or NRAS mutation did not influence the response to EGF or FGF receptor inhibitors in vitro. Our findings demonstrate that the oncogenic mutations in melanoma have a profound impact on the motogenic effect of the activation of growth factor receptor signaling. Since emerging molecularly targeted therapies aim at the growth factor receptor signaling, the appropriate mutational analysis of individual melanoma cases is essential in both preclinical studies and in the clinical trials and practice.

Prenylation inhibition-induced cell death in melanoma: reduced sensitivity in BRAF mutant/PTEN wild-type melanoma cells

While targeted therapy brought a new era in the treatment of BRAF mutant melanoma, therapeutic options for non-BRAF mutant cases are still limited. In order to explore the antitumor activity of prenylation inhibition we investigated the response to zoledronic acid treatment in thirteen human melanoma cell lines with known BRAF, NRAS and PTEN mutational status. Effect of zoledronic acid on proliferation, clonogenic potential, apoptosis and migration of melanoma cells as well as the activation of downstream elements of the RAS/RAF pathway were investigated in vitro with SRB, TUNEL and PARP cleavage assays and videomicroscopy and immunoblot measurements, respectively. Subcutaneous and spleen-to-liver colonization xenograft mouse models were used to evaluate the influence of zoledronic acid treatment on primary and disseminated tumor growth of melanoma cells in vivo. Zoledronic acid more efficiently decreased short-term in vitro viability in NRAS mutant cells when compared to BRAF mutant and BRAF/NRAS wild-type cells. In line with this finding, following treatment decreased activation of ribosomal protein S6 was found in NRAS mutant cells. Zoledronic acid demonstrated no significant synergism in cell viability inhibition or apoptosis induction with cisplatin or DTIC treatment in vitro. Importantly, zoledronic acid could inhibit clonogenic growth in the majority of melanoma cell lines except in the three BRAF mutant but PTEN wild-type melanoma lines. A similar pattern was observed in apoptosis induction experiments. In vivo zoledronic acid did not inhibit the subcutaneous growth or spleen-to-liver colonization of melanoma cells. Altogether our data demonstrates that prenylation inhibition may be a novel therapeutic approach in NRAS mutant melanoma. Nevertheless, we also demonstrated that therapeutic sensitivity might be influenced by the PTEN status of BRAF mutant melanoma cells. However, further investigations are needed to identify drugs that have appropriate pharmacological properties to efficiently target prenylation in melanoma cells.

Cell migration or cytokinesis and proliferation?--revisiting the "go or grow" hypothesis in cancer cells in vitro

The mortality of patients with solid tumors is mostly due to metastasis that relies on the interplay between migration and proliferation. The "go or grow" hypothesis postulates that migration and proliferation spatiotemporally excludes each other. We evaluated this hypothesis on 35 cell lines (12 mesothelioma, 13 melanoma and 10 lung cancer) on both the individual cell and population levels. Following three-day-long videomicroscopy, migration, proliferation and cytokinesis-length were quantified. We found a significantly higher migration in mesothelioma cells compared to melanoma and lung cancer while tumor types did not differ in mean proliferation or duration of cytokinesis. Strikingly, we found in melanoma and lung cancer a significant positive correlation between mean proliferation and migration. Furthermore, non-dividing melanoma and lung cancer cells displayed slower migration. In contrast, in mesothelioma there were no such correlations. Interestingly, negative correlation was found between cytokinesis-length and migration in melanoma. FAK activation was higher in melanoma cells with high motility. We demonstrate that the cancer cells studied do not defer proliferation for migration. Of note, tumor cells from various organ systems may differently regulate migration and proliferation. Furthermore, our data is in line with the observation of pathologists that highly proliferative tumors are often highly invasive.

The medical relations of open access initiative

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