Detection of melanoma by canine olfactory receptors
Investigator: Tatjana Abaffy
Institutional Protocol #: 20061117
National Clinical Trials Identifier: N/A
Funding Agency/Sponsor: Intramural
Division: Cancer Center
Therapeutic Area: Melanoma and Related Skin Cancers
Enrolling Sites: University of Miami Hospital & Clinics, Jackson Memorial Hospital
Enrolling Since: 7/23/2007
Purpose/Abstract:Research proposal Tatjana Abaffy, PhD
DETECTION OF MELANOMA BY CANINE OLFACTORY RECEPTORS
Melanoma is the most serious form of skin cancer and early diagnosis is the best way to combat it. It has an aggressive course and virtually no proven benefit to any non-surgical treatments . Current diagnosis is based on the results from over 100 year old biopsy analysis and studies showed that distinguishing between benign pigmented lesions and early melanomas can be difficult . The use of gene expression profiles, as molecular biomarkers, is not reliable, since there are highly diverse and also “accuracy, reproducibility, and comparability among different gene expression profile studies are low ” . The scarcity of the sample at this early stage of disease makes collection of the tissue very difficult. By primarily measuring changes in transcript and protein abundance, conventional genomics and proteomics methods failed to detect significant posttranslational events that regulate protein activity and, ultimately, malignant cell behavior.
Smell or odor has been used as a symptom of disease for centuries. Recently, patterns of biochemical markers have been found in the exhaled breath of patients with lung and breast cancers that are distinguishable from the control   [ 6]. Evidence for canine extreme olfactory ability, both in terms of detection threshold  and in terms of ability to detect melanoma , as well as lung and breast cancer samples  has been documented.
My long term objective is to develop a safe and non-invasive diagnostic tool – a biosensor for early detection of melanoma. In this proposal, I want to identify canine olfactory receptors that detect melanoma tumor markers. Candidate markers can be either direct metabolic products of melanoma tissue pathophysiology or epiphenomena. The goal of this specific research proposal is to identify canine olfactory receptors that recognize compounds specific for melanoma. Central hypothesis of this proposal is that melanoma tissue contains unique volatile and semi-volatile compounds that can be detected by canine olfactory receptors.
Aim 1. Do canine olfactory receptors recognize specific compounds present in melanoma tissue? The hypothesis is that within canine olfactory genome there are functional olfactory receptors able to detect compounds from melanoma tissue. We will isolate canine olfactory epithelium, divide it in subsections and prepare the plasma membrane “sheets” of each subsection. Membrane “sheets” consisting of olfactory receptors will be injected into Xenopus oocytes and tested using a high-throughput electrophysiology assay against both single compounds (known to elicit responses in dogs) and also against melanoma tissue homogenate (proof of principle).
Aim 2. Identification of volatile compounds that emanate from melanoma tissue as biomarkers. The hypothesis is that metabolic state of the body, in this case melanoma, alters the profile of volatile substances, i.e. its odor signature. The profile that emanates from sick tissue forms an odor signature that is different then control/normal skin samples. Profiling melanoma volatiles and comparison with control non-melanoma tissue will be studied by gas chromatography in order to find a differential pattern. The identity of the component(s) from the fraction that is present in melanoma tissue and is absent in the control (and/or vice versa), will be determined by mass spectrometry. Alternatively, the ratio between fractions will be analyzed in comparison with the ratio in control samples. The relative rather than absolute quantification will be the primary objective in this profiling.
Aim 3. Identifying the canine olfactory receptor that is activated by a volatile compound/ligand(s) from melanoma We will de-orphanize canine olfactory receptors, matching them with their potential ligand(s) isolated from melanoma tissue fraction in Aim 2. The subsection of the olfactory epithelium that gave positive response to melanoma homogenate will be analyzed by microarray analysis for identification of expressed olfactory receptors. Receptor/(s) identified from this subsection will be subcloned, heterologously expressed in Xenopus.oocytes system and tested against the potential melanoma marker (fraction) isolated in Aim 2.
Inclusion Criteria:For inclusion of melanoma participants in the study the diagnosis of malignant melanoma, Stage II and III by AJCC grouping is the inclusion criteria. For inclusion of healthy volunteers, the criteria is a mole, with a size of 0.65cm in diameter or larger.
All participants will have to be over 21 years old.
Exclusion Criteria:age, only participants >21years will participate in the research since children will be excluded from the proposed research. The reason is that melanoma is rare in children (between 10-14 years the incidence is only 0.3 per 100,000 and between ages 14-19 is 1.3 per 100,000).
Cancer Center Studies