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Acquired drug resistance is the major cause for disease recurrence in cancer patients, and this is particularly true for patients with metastatic melanoma that carry a BRAF V600E mutation. To address this problem, we investigated cyclic membrane-active peptides as an alternative therapeutic modality to kill drug-tolerant and resistant melanoma cells to avoid acquired drug resistance. We selected two stable cyclic peptides (cTI and cGm), previously shown to have anti-melanoma properties, and compared them with dabrafenib, a drug used to treat cancer patients with the BRAF V600E mutation. The peptides act via a fast membrane-permeabilizing mechanism and kill metastatic melanoma cells that are sensitive, tolerant, or resistant to dabrafenib. Melanoma cells do not become resistant to long-term treatment with cTI, nor do they evolve their lipid membrane composition, as measured by lipidomic and proteomic studies. In vivo studies in mice demonstrated that the combination treatment of cTI and dabrafenib resulted in fewer metastases and improved overall survival. Such cyclic membrane-active peptides are thus well suited as templates to design new anticancer therapeutic strategies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Immunosuppressed organ-transplant recipients have an increased incidence of, and mortality from, skin cancer. Nicotinamide (vitamin B 3 ) enhances the repair of ultraviolet (UV) radiation-induced DNA damage, reduces the cutaneous immunosuppressive effects of UV radiation, and reduces the incidence of keratinocyte cancers (including squamous-cell and basal-cell carcinomas) and actinic keratoses among high-risk immunocompetent patients. Whether oral nicotinamide is useful for skin-cancer chemoprevention in organ-transplant recipients is unclear., Methods: In this phase 3 trial, we randomly assigned, in a 1:1 ratio, organ-transplant recipients who had had at least two keratinocyte cancers in the past 5 years to receive 500 mg of nicotinamide or placebo twice daily for 12 months. Participants were examined for skin lesions by dermatologists at 3-month intervals for 12 months. The primary end point was the number of new keratinocyte cancers during the 12-month intervention period. Secondary end points included the numbers of squamous-cell and basal-cell carcinomas during the 12-month intervention period, the number of actinic keratoses until 6 months after randomization, safety, and quality of life., Results: A total of 158 participants were enrolled, with 79 assigned to the nicotinamide group and 79 to the placebo group. The trial was stopped early owing to poor recruitment. At 12 months, there were 207 new keratinocyte cancers in the nicotinamide group and 210 in the placebo group (rate ratio, 1.0; 95% confidence interval, 0.8 to 1.3; P = 0.96). No significant between-group differences in squamous-cell and basal-cell carcinoma counts, actinic keratosis counts, or quality-of-life scores were observed. Adverse events and changes in blood or urine laboratory variables were similar in the two groups., Conclusions: In this 12-month, placebo-controlled trial, oral nicotinamide therapy did not lead to lower numbers of keratinocyte cancers or actinic keratoses in immunosuppressed solid-organ transplant recipients. (Funded by the National Health and Medical Research Council; ONTRANS Australian New Zealand Clinical Trials Registry number, ACTRN12617000599370.)., (Copyright © 2023 Massachusetts Medical Society.)

Introduction: Patients with in-transit melanoma metastases present a therapeutic challenge. Complete surgical excision of localised disease is considered as the gold standard; however, surgery is not always acceptable and alternatives are required. Treatment results reported using imiquimod and diphenylcyclopropenone (DPCP) suggest that topical immunotherapies can be used to successfully treat select patients with melanoma metastases. A phase II, randomised, single centre, pilot study was designed to assess the clinical efficacy and safety of DPCP and imiquimod for the treatment of superficial, cutaneous in-transit melanoma metastases., Methods and Analysis: This is an open-label, non-superiority, pilot study with no treatment cross-over. Eligible patients are randomised in a 1:1 ratio to receive topical therapy for up to 12 months with a minimum follow-up period of 12 months. The target sample size is 30 patients, with 15 allocated to each treatment arm. The primary endpoint is the number of patients experiencing a complete response of treated lesions as determined clinically using Response Evaluation Criteria in Solid Tumours. This trial incorporates health-related quality of life measures and biological tissue collection for further experimental substudies. The study will also facilitate a health economic analysis., Ethics and Dissemination: Approval was obtained from the Human Research Ethics Committee at the participating centre, and recruitment has commenced. The results of this study will be submitted for formal publication within a peer-reviewed journal., Trial Registration Number: Prospectively registered on 16 October 2015 with the Australian New Zealand Clinical Trials Registry (ACTRN12615001088538). This study conforms to WHO Trial Registration Data Set., Competing Interests: Competing interests: TR was the recipient of a Junior Research Fellowship awarded by the Queensland Government and Clinical Research Fellowship awarded by the PA Research Foundation both of which supported the establishment of this study., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

In melanoma, therapies with inhibitors to oncogenic BRAF V600E are highly effective but responses are often short-lived due to the emergence of drug-resistant tumor subpopulations. We describe here a mechanism of acquired drug resistance through the tumor microenvironment, which is mediated by human tumor-associated B cells. Human melanoma cells constitutively produce the growth factor FGF-2, which activates tumor-infiltrating B cells to produce the growth factor IGF-1. B-cell-derived IGF-1 is critical for resistance of melanomas to BRAF and MEK inhibitors due to emergence of heterogeneous subpopulations and activation of FGFR-3. Consistently, resistance of melanomas to BRAF and/or MEK inhibitors is associated with increased CD20 and IGF-1 transcript levels in tumors and IGF-1 expression in tumor-associated B cells. Furthermore, first clinical data from a pilot trial in therapy-resistant metastatic melanoma patients show anti-tumor activity through B-cell depletion by anti-CD20 antibody. Our findings establish a mechanism of acquired therapy resistance through tumor-associated B cells with important clinical implications.Resistance to BRAFV600E inhibitors often occurs in melanoma patients. Here, the authors describe a potential mechanism of acquired drug resistance mediated by tumor-associated B cells-derived IGF-1.

Despite favorable advancements in therapy cancer is still not curative in many cases, which is often due to inadequate specificity for tumor cells. In this study derivatives of a short cationic peptide derived from the human host defense peptide lactoferricin were optimized in their selective toxicity towards cancer cells. We proved that the target of these peptides is the negatively charged membrane lipid phosphatidylserine (PS), specifically exposed on the surface of cancer cells. We have studied the membrane interaction of three peptides namely LF11-322, its N-acyl derivative 6-methyloctanoyl-LF11-322 and its retro repeat derivative R(etro)-DIM-P-LF11-322 with liposomes mimicking cancerous and non-cancerous cell membranes composed of PS and phosphatidylcholine (PC), respectively. Calorimetric and permeability studies showed that N-acylation and even more the repeat derivative of LF11-322 leads to strongly improved interaction with the cancer mimic PS, whereas only the N-acyl derivative also slightly affects PC. Tryptophan fluorescence of selective peptide R-DIM-P-LF11-322 revealed specific peptide penetration into the PS membrane interface and circular dichroism showed change of its secondary structure by increase of proportion of β-sheets just in the presence of the cancer mimic. Data correlated with in vitro studies with cell lines of human melanomas, their metastases and melanocytes, revealing R-DIM-P-LF11-322 to exhibit strongly increased specificity for cancer cells. This indicates the need of high affinity to the target PS, a minimum length and net positive charge, an adequate but moderate hydrophobicity, and capability of adoption of a defined structure exclusively in presence of the target membrane for high antitumor activity.

Hexadecylphosphocholine (HePC), an ether lipid analogue, is a new antineoplastic drug which has been shown to exert a remarkable antiproliferative effect in vitro and in vivo. The signal transduction pathway and the phospholipid synthesis are thought to be the main putative molecular targets of HePC, yet the exact mechanism of action is still unclear. To investigate the antiinvasive activity of HePC on a mouse T-cell lymphoma cell line (BW-O-Li1), we used a type I collagen gel and devitalized dermis as substrate to evaluate the migration of BW-O-Li1 after exposure to HePC. BW-O-Li1 cells were exposed for 24 h to a non-cytotoxic (10 microM) as well as to cytotoxic concentrations of HePC. Afterwards, BW-O-Li1 cells were seeded on top of a reconstituted collagen gel layer or pippeted into a steel ring placed on the dermal site of a devitalized dermis. Lymphoma cells, which invaded the collagen layer were counted by light microscopy, invasion into devitalized dermis was measured by an image analysis system. Compared to unexposed cells, invasion into the collagen gel differed significantly even at 10 microM HePC, whereas the absolute number of invading cells, independently of the HePC concentration, showed no difference in the amount of counted cells. Migration into devitalized dermis was significantly reduced for 10 microM and 40 microM HePC. These data show that complementary information can be obtained by application of the two invasion assays and that the antiinvasive effect of HePC emerges at non-cytotoxic concentrations of the substance.

Up to 4 h after treatment of human SW 707 colon carcinoma cells with the antineoplastic drug 4-amino-N-(2'-aminophenyl)-benzamide (GOE 1734, dinaline), the effects of tumour cell metabolism and proliferation were examined in vitro. Four tracers which can be labelled with isotopes suitable for positron emission tomography (PET) were used for this purpose: alpha-aminoisobutyric acid (AIB) and methionine to study changes in amino acid transport and protein synthesis, thymidine to observe changes in tumour proliferation and 2-fluoro-2-deoxy-D-glucose (FDG) to estimate glucose metabolism. Dinaline showed an inhibition of the sodium-dependent and -independent uptake of AIB. The methionine uptake was found to increase shortly after therapy. Thymidine incorporation into DNA was impaired and the FDG uptake showed a maximally 2.2-fold enhancement. Inhibition of AIB uptake suggests changes in amino acid transport, whereas increased uptake of methionine and FDG points to an enhancement of protein synthesis and glycolysis caused by repair mechanisms. The cytostatic and antiproliferative effect of dinaline, observed in cell growth curves, could be demonstrated by the impaired thymidine incorporation into DNA. This study demonstrates that in vitro screening with radiotracers suitable for PET can help to clarify effects of new antineoplastic substances on tumour cell metabolism. These data may be applied to choose the appropriate time schedule for monitoring therapeutic effects on tumour tissue.

The human colon carcinoma cell line SW707 was incubated with different concentrations (7 microM - 540 microM) of the novel antineoplastic drug 4-amino-N(2'-aminophenyl)benzamide (GOE1734, dinaline) to study the effects on 3H-alpha-aminoisobutyric acid (AIB) - and 14C-methionine uptake as well as on 3H-thymidine incorporation into DNA. Additionally, adenine nucleotide pools were determined by high performance liquid chromatography (h.p.l.c.), and cell cycle distribution by flow cytometry. 24 h exposure to low concentrations of dinaline caused mild cell proliferation which turned into a cytostatic effect within a further 24 h without drug exposure. High concentrations of dinaline, however, were found to be cytostatic and then cytotoxic after corresponding time intervals. Dinaline caused a concentration-dependent decrease in sodium-dependent AIB uptake. Immediately after exposure the effect ranged from 67%-36% of control uptake. One day later an incomplete recovery not exceeding 70% of control was found for the three highest concentrations. This differed significantly from sodium-dependent methionine uptake which was initially decreased by 24%-36% but recovered within one hour and was enhanced one day after exposure. Significant differences were also measured for sodium-independent AIB uptake and sodium-independent methionine uptake immediately, 1 and 4 h after exposure. Adenine nucleotide pools were mildly increased immediately and 4 h after exposure. Thymidine incorporation into DNA was decreased by 70% to 84% immediately after exposure, and no full recovery was seen in the subsequent observation period. Cell cycle analyses revealed a block at the S phase entrance. Changes in thymidine incorporation and S phase fraction were highly correlated. The inhibition of the sodium-dependent uptake of AIB might indicate interaction of dinaline with cell membrane functions at low concentrations, the increase in methionine uptake points to enhanced protein synthesis following drug withdrawal and the impaired thymidine incorporation into DNA results from the cytostatic effect of dinaline. Taken together, the results show that SW707 colon carcinoma cells exposed to dinaline demonstrate distinct but reversible changes in amino acid transport, protein metabolism, DNA synthesis and cell proliferation, thus giving a correlation with observations in vivo.

The human colon carcinoma cell line SW 707 was exposed for up to 72 h to the new antineoplastic agent 4-amino-N-(2'-aminophenyl)benzamide (GOE 1734, dinaline). Thereafter, uptake measurements with fluorodeoxy-[14C]glucose (FdGlc) were performed and cell-cycle fractions as well as adenine nucleotide pools were determined by flow cytometry and HPLC. One day after a 24 h exposure to 20-540 microM dinaline a 2.0-to 2.5-fold enhancement of FdGlc uptake was observed, and the values after 48-h or 72-h incubations showed a 2.5- to 3.5-fold or a 2.0-fold increase respectively. For all periods of exposure a diminished S phase (3%-71% of control) was found initially after incubation, demonstrating the antiproliferative effect of dinaline, with total recovery after 1 day. Adenine nucleotide pools were not diminished concomitantly. The enhanced FdGlc uptake caused by dinaline was the basis for choosing 2-deoxyglucose (dGlc) as the combination partner, which acts as an antimetabolite to enzymes involved in glucose metabolism. Several combinations of dinaline and dGlc were analyzed for their effects on growth inhibition. Almost 50% additional decrease in cell number as compared to monotherapy with dinaline was found after coexposure to 12 mM dGlc and 20 microM dinaline 24 h after incubation. Similar effects were observed 2 days after incubation with the two drugs. After 3 days, the cell numbers reached monotherapy levels. Since the cytostatic effect of dinaline could be enhanced by dGlc although incubation with dGlc alone caused no changes in cell number, the combined effect of both agents is synergistic. These results imply that dinaline might have applications in combination treatment in vivo.

Objectives: Is there a correlation between cell cycle perturbations and cytotoxicity in ovarian cancer cells exposed to cytotoxic drugs in vitro?, Methods: We tested the association between cytotoxicity and in vitro cell cycle perturbations after exposure of human ovarian cancer cells to seven cytotoxic agents., Results: Three principal patterns of cell cycle alterations were observed; a sequential S-G/M block after exposure to the non phase-specific agents cis-platinum, 4-hydroperoxy-eyclophosphamide, and mitomycin C (Group I); an isolated G2/M block after exposure to the G2/M phase-specific drugs etoposide and vincristine (Group II); and an isolated S block following exposure to the S phase-specific agents 5-fluorouracil and cytosine arabinoside (Group III). Overall, there was no direct correlation between the degree of cell cycle perturbations and cytotoxicity. However, when the three subgroups of phase non-specific agents, S phase-specific agents, and G2/M specific agents were analyzed separately, positive correlations between the magnitude of cell kinetic alterations and cytotoxicity were observed., Conclusions: Cell kinetic alterations appeared to precede cytotoxicity. The experimental model may be particularly useful to study cell kinetic effects after high-dose chemotherapy since, in contrast to conventional chemotherapy, the magnitude of cell kinetic perturbations after this kind of treatment is significantly increased.