Novel α-MSH Peptide Analogs for Melanoma Targeting

Skin cancer is the one of the most diagnosed cancers in the United States with increasing incidence over the past two decades. There are three major forms of skin cancer but melanoma is the deadliest. It is estimated that 76,690 new diagnoses of melanoma and 9,480 deaths will occur in 2013. Melanoma accounts for approximately 1.6% of all cancer related deaths and is the 5th leading diagnosed cancer in the United States. The mean survival rate of patients diagnosed with metastatic melanoma is six months, with five year survival rates of less than 5%. In this project, we describe the design and characterization of novel melanoma-targeting peptide analogs for use in diagnostic imaging of both primary and metastatic melanoma lesions. Novel α-MSH peptide conjugates were designed to target the melanocortin-1 receptor present and over-expressed on melanoma cells. These peptides were synthesized and their in-vitro melanocortin-1 receptor binding affinities were established in murine melanoma cells. Once binding affinities were determined, the peptides were radiolabeled with 99mTc utilizing a novel direct radiolabeling technique developed in our laboratory. The peptides were purified via reverse-phase high performance liquid chromatography and in-vivo melanoma targeting and pharmacokinetic properties were determined in B16/F1 melanoma-bearing female C57BL/6 mice. Biodistribution and SPECT/CT imaging studies were performed with the promising 99mTc-labeled peptide conjugates. All α-MSH peptide conjugates tested showed low nanomolar binding affinity for the melanocortin-1 receptor. All peptides were readily radiolabeld with 99mTc with greater than 95% radiochemical purity. All 99mTc-labeled peptides displayed high specific in-vivo melanoma tumor uptake while maintaining low normal organ accumulation, and were excreted through the urinary system in a timely fashion. In addition, all tested 99mTc-labeld α-MSH peptides demonstrated clear visualization of in-vivo tumor lesions with SPECT/CT. While all peptides exhibited high melanoma uptake, extremely high non-specific renal uptake was of concern. After synthesis of α-MSH peptide conjugates containing a different amino acid linker, renal uptake was drastically reduced and a lead compound had emerged, showing favorable in-vivo melanoma targeting and uptake properties with limited amounts of non-specific renal accumulation

Effectiveness of stress relieving strategies in regulating patterns of cortisol secretion and promoting brain health

Stress leads to ill-health and disease, and with today’s fast-pace western society, engaging in strategies to relieve stress is crucial for good health across the life course. Activities such as focusing on positive characteristics, art/music therapies, mindfulness, yoga and engaging with nature and/or physical activity have been shown to reduce stress and enhance well-being. It is thought that patterns of cortisol secretion, which are regulated by the brain, are a key mediator of stress-disease and well-being-health links. Measurement of cortisol in saliva is a non-invasive and ecologically valid tool for detecting early changes in brain health, as well as evaluating the effectiveness of strategies in relieving stress and improving brain health as well as monitoring stress related brain changes. This chapter will review the evidence that engaging in stress relieving strategies promotes regulation and/or restoration of patterns of cortisol secretion. If such strategies are found to be effective in healthy populations, they could potentially inform ways of promoting brain health and the prevention or delay of clinical disorders involving disorders in the brain (e.g. Parkinson’s Disease) and symptoms experienced with such disorders. To inform this field of research, recommendations are provided for the use of salivary cortisol as a marker of early monitoring of brain health and effectiveness of stress-alleviating interventions

2017 Research & Innovation Day Program

A one day showcase of applied research, social innovation, scholarship projects and activities.https://first.fanshawec.ca/cri_cripublications/1004/thumbnail.jp

Enhanced Doxorubicin Chemotherapy Efficacy in a Carbonyl Reductase 1 Knockout (Cbr1+/-) Mouse Model

Doxorubicin is one of the most effective anti-tumor anthracycline drugs used today to reduce cancerous tumor proliferation. The efficacy of this drug relies on high circulating concentrations and its metabolism in the body can be disrupted by reducing enzymes into its cardiotoxic and chemotherapeutically less effective metabolite, doxorubicinol. In vivo studies show that carbonyl reductase 1 is the enzyme responsible for the metabolism of doxorubicin. By genetically engineering mice that contain only one copy of the carbonyl reductase 1 gene (Cbr1+/- mice), rduced expression of the enzyme is seen, and less of the parent drug is converted. Transgenic mice containing the polyoma middle T antigen (PyVT) and promoter sequence from the mouse mammary tumor virus (MMTV), which are susceptible to forming tumors in the mammary glands, were bred to C57B16/J and 129SVE Cbr1 knockout mice. The offspring of these matings developed measureable mammary tumors. Upon total tumor volume reaching approximately 200 mm3, the mice were given a chemotherapy treatment of doxorubicin at a dosage of 2 mg/kg for nine consecutive days. During and up to sixteen days after the chemotherapy treatment, mammory tumor volume was measured for data analysis. Tumor regression was analyzed for sex, genotype, and gentic background by the percent change of total tumor volume from the initiation of treatment using the NCSS ver. 2007 and R ver. 2.7.2 statistical software packages. It was determined that mice with only one copy of Cbr1 gene had improved tumor regression and enhanced doxorubicin efficacy as compared to their wild type littermates. Our data show synthesis of a Cbr1 drug inhibitor may increase the power of chemotherapy treatment against cancer proliferation while reducing carditoxic effects

Sex Differences in Improved Efficacy of Doxorubicin Chemotherapy in Cbr1+/- Mice

The anthracycline chemotherapeutic agent doxorubicin is converted by the enzyme carbonyl reductase 1 (CBR1) into its cardiotoxic metabolite doxorubicinol. Cbr1+/− mice have been shown to be protected from doxorubicin-induced cardiotoxicity, and the inhibition of CBR1 activity may be a useful means of ameliorating the side effects of doxorubicin in patients undergoing chemotherapy. Because reduced conversion to doxorubicinol increases circulating levels of the more effective parent drug doxorubicin, it was hypothesized that therapeutic efficacy against tumors might also be enhanced. Cbr1+/− mice were bred to mice transgenic for the polyomavirus middle T antigen (PyVT) to create offspring with palpable mammary tumors. Latency to initial tumor formation was similar in Cbr1+/− and Cbr1+/+ animals. Tumor regression was improved in Cbr1+/− animals, but only in male mice. Western blotting showed a marked sex difference in protein levels, with a much higher expression of Cbr1 in the female kidney and liver. Thus, the combined effects of a naturally low expression and the heterozygous Cbr1 null allele seem to have enhanced tumor regression in Cbr1+/− males. Future efforts to design a clinical CBR1 inhibitor to protect patients from the cardiac side effects of doxorubicin treatment should evaluate the effect of sex on anticancer efficacy