Genetic Mutations Tested In Zebrafish

The zebrafish is a potential tool for testing one class of unique individual genetic differences found in humans, and may yield information helpful for the emerging field of personalized medicine, according to a team led by Penn State College of Medicine scientists. The differences, or mutations, in question create minor changes in amino acids -- the building blocks of DNA -- from person to person. Zebrafish can be used as a model to understand what biological effects result from these genetic mutations.

Personalized medicine uses modern technology and tools to find biological and genetic differences in individuals so that treatment is more effectively delivered.

"A major challenge of personalized medicine is the lack of a standard way to define the importance of each of the many unique mutations found in an individual's genetic code," said Keith Cheng, M.D., Ph.D., professor of pathology and lead researcher. "Approaches are particularly needed to experimentally determine what differences these mutations make. It is difficult to distinguish the effects of a single amino acid change caused by those changes in our DNA."

The zebrafish is a good choice because of its similarity to humans as a vertebrate, its transparency as an embryo and the powerful genetic tools available in this model organism.

The Cheng lab's approach is like testing small damages in car parts, one at a time. For example, a "mutant" car headlight is known not to work when a certain connector is missing. Taking a normally functioning connector out of a working headlight and replacing it with a connector damaged in a specific way -- a cracked wire casing or a corroded wire connector, for example -- can show whether the damage matters. If the light works, then that mutation makes no difference on the function of the headlight. If the light does not work, the mutation has an effect.

Postdoctoral fellow Zurab Tsetskhladze, who performed the zebrafish experiments, tested this method with two genes that affect skin color. He started with an equivalent of the broken car part: mutant zebrafish with lighter pigment cells. First, Tsetskhladze confirmed that by injecting normal messenger RNA (ribonucleic acid) into the mutant zebrafish, the lighter pigment cells become "cured" -- or darker -- like those of a normal zebrafish. Messenger RNA makes the cells produce the protein the scientists want to study.

Tsetskhladze was then able to test RNA with only one "human" mutation to see if cure was still possible. Cure suggests that the mutation does not matter. If cure is prevented by the mutation, the conclusion is that the protein's function is affected by the amino acid difference being tested.

Cheng's lab works with zebrafish to study genetic differences that contribute to human skin color. Scientists want to determine the role these differences play in the development of skin cancer, and to find ways to better protect people from cancer.

In the current study, two of the amino acid differences that Cheng has shown in prior studies to contribute to light skin color in humans prevented the zebrafish color from darkening. A third amino acid difference that is common in Eastern Asians was of unknown effect. The researchers found that the change made no difference in function in zebrafish. This finding matched the findings of K.C. Ang, postdoctoral fellow, who found no effect of the tested change on the skin color of East Asians.

To see if this approach might be used in other ways, Stephen Wentzel, graduate student, Penn State College of Medicine, looked at mutations in the four genes known to contribute to albinism, which lightens the color of skin, eyes and hair, and is associated with any one of more than 250 known single amino acid differences. He found that at least 210 of these are theoretically testable in the zebrafish. This new test may help scientists to determine which mutations can be ignored and which may need action - such as a change in life habit.

"This approach may potentially be extended to other biological functions and may therefore be useful in personalized medicine," Cheng said.

Fighting Melanoma's Resistance To Chemotherapy

Blocking the action of a particular protein in our skin could improve the treatment of skin cancers, according to a study published in Oncogene by Philippe Roux, a researcher at the University of Montreal's Institute for Research in Immunology and Cancer (IRIC). "Our findings reveal part of the mechanisms responsible for the resistance of melanoma to anti-cancer treatments, and suggest that a particular protein in our bodies called RSK may be targeted in combination therapies to overcome drug resistance," Roux explained.

Although melanoma accounts for only 4% of all skin cancers, it is responsible for 80% of skin cancer-related deaths worldwide as it is highly invasive and resistant to conventional chemotherapies. Melanoma originates from pigment-producing cells, called melanocytes, located in the skin. The incidence of malignant melanoma is growing rapidly worldwide and there is still no effective therapy to treat it. Approximately 160,000 new cases of the disease are diagnosed each year.

Roux and his team focused their research on a signaling pathway called Ras/MAPK, which is often deregulated in melanoma, but also in lung, colon and pancreatic cancers. A signaling pathway is a chemical chain reaction that causes the cells in our bodies to act in a certain way. In this study, Roux and his team found that a protein in the Ras/MAPK pathway, RSK, contributes to chemoresistance by altering the response of cancer cells to chemotherapeutic agents.

This is the second Oncogene publication for Philippe Roux this year. In a paper published in July, Roux and his colleagues, IRIC Principal Investigators Katherine Borden and Sylvain Meloche, demonstrated that the same protein involved in chemoresistance contributes to melanoma growth, making the protein RSK a promising therapeutic target for treating the disease.

How Patterns, Timing Of Sunlight Exposure Contribute To Skin Cancers

Researchers at Moffitt Cancer Center, the University of South Florida and the International Agency for Research on Cancer in France have studied the patterns and timing of sunlight exposure and how each is related to two nonmelanoma skin cancers - basal cell carcinoma and squamous cell carcinoma.

This study, published in the open-access journal BioMed Central, is the first case-control study to simultaneously evaluate identical patterns and timing of sunlight exposure as they are related to basal cell and squamous cell carcinomas in the same U.S. population with high annual ultraviolet radiation exposure. Patterns of sunlight exposure are continuous or intermittent, and timing refers to exposure during childhood, adulthood or both. It included 703 Florida residents - 218 with basal cell carcinoma, 169 with squamous cell carcinoma and 316 without skin cancer. The research goal was to identify potential differences or similarities in sunlight exposure responses for basal cell and squamous cell carcinomas.

"There are more than a million new cases of basal cell and squamous cell carcinomas diagnosed in the United States each year," said senior study author Dana E. Rollison, Ph.D., associate member of the Cancer Epidemiology Program, and vice president and chief health information officer at Moffitt. "While mortality associated with nonmelanoma skin cancers, such as basal cell and squamous cell carcinomas, is low, patients may experience substantial morbidity and treatment costs are high."

It is estimated that 25 percent of lifetime sunlight exposure occurs before age 18. Youth is a time of greater toxic sunlight exposure and also a time when the chances of receiving blistering sunburns are higher.

"Blistering sunburn is believed to result from high doses of intense ultraviolet radiation exposure in short increments of time and is considered to be a measure of intermittent exposure," said study co-author Michelle Iannacone, Marie Curie postdoctoral fellow at the International Agency for Research on Cancer.

The researchers surveyed those with basal cell and squamous cell carcinomas, as well as those with no history of skin cancer, to determine the effects of intermittent versus continuous sunlight exposure, as well as the timing of the exposure and age. They noted that although the relationship between both cancers and sunlight exposure is complex, researchers began to identify cumulative outdoor sunlight exposure as a risk factor for nonmelanoma skin cancer beginning in the 1950s.

Being exposed to ultraviolet radiation intermittently, perhaps while on summer vacation in high ultraviolet radiation regions, and continuous exposure through working at a job outside in the sunlight were patterns the researchers wanted to identify and correlate to basal cell and squamous cell carcinomas.

Study subjects were surveyed on their recollections of their history of sun exposure.

Survey results reveal that a history of blistering sunburn was associated with both basal cell and squamous cell carcinomas. Having a job in the sunlight was also associated with basal cell and squamous cell carcinomas. Measures of younger age at sunlight exposure "tended to be associated with squamous cell carcinoma, but not basal cell carcinoma, risk," researchers concluded.

"Sunlight exposure, regardless of the exposure pattern, is associated with both basal cell and squamous cell carcinomas," Iannacone said. "Understanding how sunlight exposure response may differ by nonmelanoma skin cancer type is important for educating the public on safe sunlight behaviors. Applying sunscreen while on vacation may decrease basal cell carcinoma risk with intermittent sunlight exposure, but may not impact the risk of squamous cell carcinoma, which may be more strongly related to continuous sunlight exposure."

View the Original article

Advanced Melanoma Tumors Eradicated In Mouse Model

5 (1 votes)

Cancers arise in the body all the time. Most are nipped in the bud by the immune response, not least by its T cells, which detect telltale molecular markers - or antigens - on cancer cells and destroy them before they grow into tumors. Cancer cells, for their part, evolve constantly to evade such assassination. Those that succeed become full-blown malignancies. Yet, given the right sort of help, the immune system can destroy even these entrenched tumors.

In the Journal of Experimental Medicine, researchers led by Jedd Wolchok, MD, PhD, of the Ludwig Center for Cancer Immunotherapy at Memorial Sloan-Kettering Cancer Center (MSKCC) in New York describe one way in which that might be achieved. The paper relates how the cancer drug cyclophosphamide (CTX) and OX86 - an antibody that activates a molecule named OX40 on T cells - were combined with a cutting-edge therapy known as adoptive T cell transfer to eradicate advanced melanoma tumors in mice.

Wolchok and his colleagues had previously shown that CTX and OX86 treatment caused the regression of such tumors. Now they wanted to see if adding T cell transfer to the mix would further improve outcomes. T cell transfer is an investigative immunotherapy in which T cells that target tumors are isolated from patients, manipulated, expanded and then transfused back into those patients.

A variety of T cells are of relevance to this approach. One is the CD8

View the Original article

Genetic Mutations Tested In Zebrafish

The zebrafish is a potential tool for testing one class of unique individual genetic differences found in humans, and may yield information helpful for the emerging field of personalized medicine, according to a team led by Penn State College of Medicine scientists. The differences, or mutations, in question create minor changes in amino acids -- the building blocks of DNA -- from person to person. Zebrafish can be used as a model to understand what biological effects result from these genetic mutations.

Personalized medicine uses modern technology and tools to find biological and genetic differences in individuals so that treatment is more effectively delivered.

"A major challenge of personalized medicine is the lack of a standard way to define the importance of each of the many unique mutations found in an individual's genetic code," said Keith Cheng, M.D., Ph.D., professor of pathology and lead researcher. "Approaches are particularly needed to experimentally determine what differences these mutations make. It is difficult to distinguish the effects of a single amino acid change caused by those changes in our DNA."

The zebrafish is a good choice because of its similarity to humans as a vertebrate, its transparency as an embryo and the powerful genetic tools available in this model organism.

The Cheng lab's approach is like testing small damages in car parts, one at a time. For example, a "mutant" car headlight is known not to work when a certain connector is missing. Taking a normally functioning connector out of a working headlight and replacing it with a connector damaged in a specific way -- a cracked wire casing or a corroded wire connector, for example -- can show whether the damage matters. If the light works, then that mutation makes no difference on the function of the headlight. If the light does not work, the mutation has an effect.

Postdoctoral fellow Zurab Tsetskhladze, who performed the zebrafish experiments, tested this method with two genes that affect skin color. He started with an equivalent of the broken car part: mutant zebrafish with lighter pigment cells. First, Tsetskhladze confirmed that by injecting normal messenger RNA (ribonucleic acid) into the mutant zebrafish, the lighter pigment cells become "cured" -- or darker -- like those of a normal zebrafish. Messenger RNA makes the cells produce the protein the scientists want to study.

Tsetskhladze was then able to test RNA with only one "human" mutation to see if cure was still possible. Cure suggests that the mutation does not matter. If cure is prevented by the mutation, the conclusion is that the protein's function is affected by the amino acid difference being tested.

Cheng's lab works with zebrafish to study genetic differences that contribute to human skin color. Scientists want to determine the role these differences play in the development of skin cancer, and to find ways to better protect people from cancer.

In the current study, two of the amino acid differences that Cheng has shown in prior studies to contribute to light skin color in humans prevented the zebrafish color from darkening. A third amino acid difference that is common in Eastern Asians was of unknown effect. The researchers found that the change made no difference in function in zebrafish. This finding matched the findings of K.C. Ang, postdoctoral fellow, who found no effect of the tested change on the skin color of East Asians.

To see if this approach might be used in other ways, Stephen Wentzel, graduate student, Penn State College of Medicine, looked at mutations in the four genes known to contribute to albinism, which lightens the color of skin, eyes and hair, and is associated with any one of more than 250 known single amino acid differences. He found that at least 210 of these are theoretically testable in the zebrafish. This new test may help scientists to determine which mutations can be ignored and which may need action - such as a change in life habit.

"This approach may potentially be extended to other biological functions and may therefore be useful in personalized medicine," Cheng said.

View the Original article

Fighting Melanoma's Resistance To Chemotherapy

Blocking the action of a particular protein in our skin could improve the treatment of skin cancers, according to a study published in Oncogene by Philippe Roux, a researcher at the University of Montreal's Institute for Research in Immunology and Cancer (IRIC). "Our findings reveal part of the mechanisms responsible for the resistance of melanoma to anti-cancer treatments, and suggest that a particular protein in our bodies called RSK may be targeted in combination therapies to overcome drug resistance," Roux explained.

Although melanoma accounts for only 4% of all skin cancers, it is responsible for 80% of skin cancer-related deaths worldwide as it is highly invasive and resistant to conventional chemotherapies. Melanoma originates from pigment-producing cells, called melanocytes, located in the skin. The incidence of malignant melanoma is growing rapidly worldwide and there is still no effective therapy to treat it. Approximately 160,000 new cases of the disease are diagnosed each year.

Roux and his team focused their research on a signaling pathway called Ras/MAPK, which is often deregulated in melanoma, but also in lung, colon and pancreatic cancers. A signaling pathway is a chemical chain reaction that causes the cells in our bodies to act in a certain way. In this study, Roux and his team found that a protein in the Ras/MAPK pathway, RSK, contributes to chemoresistance by altering the response of cancer cells to chemotherapeutic agents.

This is the second Oncogene publication for Philippe Roux this year. In a paper published in July, Roux and his colleagues, IRIC Principal Investigators Katherine Borden and Sylvain Meloche, demonstrated that the same protein involved in chemoresistance contributes to melanoma growth, making the protein RSK a promising therapeutic target for treating the disease.

View the Original article

Michigan State announces epic 'Gran Fondo' cycling event for 2013 to fund skin cancer research

Bicyclists will want to start training big time for a monstrous new event starting next year, where a good cause will be worth feeling the burn.

Share

Top medical innovations address headache, diabetes, cancer

The best medical innovations for next year include an almond-size device that's implanted in the mouth to relieve severe headaches and a hand-held scanner resembling a blow dryer that detects skin cancer, the Cleveland Clinic said on Wednesday.

Share

Health Matters: New Drug for High Risk Basal Cell Skin Cancer

"They have found different spots, mostly on my arms and on my back, from being out in the sun when I was younger," says Bob Davies, who battles with basal cell carcinoma.

Share

Routine blood test predicts prognosis in aggressive skin cancer

A routine blood test may help predict survival in patients with an aggressive form of skin cancer known as Merkel cell carcinoma, according to new findings by Fox Chase Cancer Center researchers.

Share

Pigment find may help cancer fight

The type of skin pigment found in red-haired and fair-skinned people may contribute to the development of melanoma, a finding which could lead to new skin cancer prevention methods, a study has found.

Share

Trial Of Genetically Engineered Immune System To Fight Melanoma

Main Category: Melanoma / Skin Cancer
Also Included In: Genetics;  Immune System / Vaccines
Article Date: 04 Oct 2012 - 0:00 PDT



View the Original article

Mouse Model Shows Risk For Asthma, Allergies May Improve Fight Against Skin Cancer

Main Category: Allergy
Also Included In: Melanoma / Skin Cancer;  Respiratory / Asthma
Article Date: 17 Oct 2012 - 0:00 PDT



View the Original article

'ACT TIL' Approach Studied For The Treatment Of Metastatic Melanoma

Main Category: Melanoma / Skin Cancer
Also Included In: Immune System / Vaccines;  Clinical Trials / Drug Trials
Article Date: 20 Oct 2012 - 0:00 PDT



View the Original article

China's Increasing Cancer Rates Linked To Industrialization, New Lifestyles And Lack Of Sun Exposure

Editor's Choice
Main Category: Melanoma / Skin Cancer
Also Included In: Cancer / Oncology
Article Date: 16 Aug 2012 - 13:00 PDT



View the Original article

Combining BRAF Inhibitor And Immunotherapy Increases Antitumor Activity In Metastatic Melanoma

BRAF Inhibitor Zelboraf Boosts Effectiveness of Immunotherapy in Mouse Model

Combining the recently approved BRAF inhibitor, Zelboraf with an engineered T cell immunotherapy to treat metastatic melanoma significantly increased tumor responses and survival in an animal model, researchers at UCLA's Jonsson Comprehensive Cancer Center have shown.

The animals in the study that received the combination therapy had better tumor responses and lived more than twice as long as those getting the BRAF inhibitor or immunotherapy alone. The findings provide strong support for testing the combination therapy in human clinical trials, which Jonsson Cancer Center researchers hope to launch within two years.

About 50 percent of patients with metastatic melanoma, or 4,000 people a year, have the BRAF mutation and can be treated with Zelboraf. More than 50 percent of those respond well to the drug, but the responses usually last only a few months. With immunotherapy, fewer patients respond, but the responses are more durable.

By pairing the combination therapy in a one-two punch, researchers hope to maintain the high response rates associated with Zelboraf and combine them with the longer disease-free progression times seen with immunotherapy, said study first author Dr. Richard Koya, a Jonsson Cancer Center scientist and an assistant professor of surgical oncology.

"The idea was to target two different aspects of anti-cancer biology, hitting the tumor cells themselves with the BRAF inhibitor and adding in T cells educated to induce a specific anti-tumor immune response," Koya said. "The results we saw in this study were very promising."

The findings of the two-year study appear Aug. 15, 2012 in the peer-reviewed journal Cancer Research.

The researchers also found that the BRAF inhibitor helped boost the power of the immunotherapy, creating a greater combination effect, said study senior author Dr. Antoni Ribas, a Jonsson Cancer Center scientist and a professor of hematology/oncology.

"We found that both treatments were more effective when administered together, and we were surprised to see that a drug that should only be targeting the BRAF-mutant cancer cells was also having a beneficial effect on the T cells," Ribas said.

In the immunotherapy technique, called adoptive T cell transfer or ACT, lymphocytes are genetically engineered to express a receptor that recognizes melanoma cells, creating an army of immune cells that attack the cancer. The lymphocytes are modified genetically to become specific to the melanoma cells and are injected into the body.

The study was done using a model based on unique cell lines developed at UCLA. Previously, no implantable BRAF mutation-driven melanoma model able to grow progressively in a mouse with a fully competent immune system was available.

It is vital to develop new drugs to treat metastatic melanoma as few options are available for patients. Zelboraf works well, but most patients eventually relapse.

"This is a patient population that we are not able to cure," Koya said. "With what we have now we are just prolonging their lives. We need to have more options, and we hope this combination therapy proves to be an effective alternative."

About 70,000 new cases of melanoma are diagnosed each year in the United States. Of those, 8,000 people will die of the disease.

"In conclusion, combined therapy with the BRAF-specific inhibitor Zelboraf and T cell receptor engineered adoptive cell transfer resulted in superior anti-tumor effects," the study states. "Although the absolute number of T cells infiltrating the tumor was not increased by Zelboraf, the combination increased the functionality of antigen-specific T lymphocytes. Therefore, our studies support the clinical testing of combinations of BRAF targeted therapy and immunotherapy for patients with advanced melanoma."

The study was funded by the National Cancer Institute at the National Institutes of Health (P50 CA086306 and P01 CA 132681), Seaver Institute, Louise Belley and Richard Schnarr Fund, Wesley Coyle Memorial Fund, Garcia-Corsini Family Fund, Fred L. Hartley Family Foundation, Ruby Family Foundation, Jonsson Cancer Center Foundation, Caltech-UCLA Joint Center for Translational Medicine, UCLA Tumor Biology Program, U.S. Department of Health and Human Services, Ruth L. Kirschstein Institutional National Research Service Award, Eugene V. Cota-Robles Fellowship and National Science Foundation Competitive Edge Fellowship.

View drug information on Zelboraf.

View the Original article

By Studying Animal Health, Researchers Find Improved Ways For Developing, Testing Cancer Therapies

Main Category: Melanoma / Skin Cancer
Also Included In: Immune System / Vaccines;  Pancreatic Cancer
Article Date: 17 Aug 2012 - 1:00 PDT



View the Original article

Unprecedented Moon Shots Program Launched By UT MD Anderson Cancer Center

Main Category: Cancer / Oncology
Also Included In: Lymphoma / Leukemia / Myeloma;  Melanoma / Skin Cancer
Article Date: 25 Sep 2012 - 1:00 PDT



View the Original article

Resistance In Melanoma Patients Delayed By Combination Of Targeted Treatment Drugs

Combined treatment with two drugs targeting different points in the same growth-factor pathway delayed the development of treatment resistance in patients with BRAF-positive metastatic malignant melanoma. The results of a phase I/II study of treatment with the kinase inhibitors dabrafenib and trametinib were published in the New England Journal of Medicine and released online to coincide with a presentation at the European Society for Medical Oncology meeting in Vienna.

"We investigated this combination because of research we and others have conducted into the molecular underpinnings of resistance to BRAF inhibitor therapy," says Keith Flaherty, MD, of the Massachustts General Hospital (MGH) Cancer Center, lead author of the NEJM report and principal investigator of the study. "We found that adding the MEK inhibitor trametinib to BRAF inhibitor dabrafenib clearly delays the emergence of resistance. In fact, the combination was at least twice as effective as BRAF inhibition alone."

In around half of patients with metastatic melanoma, tumor growth is driven by mutations that keep the BRAF protein - part of the MAPK cell growth pathway - constantly activated. In recent years, drugs that inhibit BRAF activity have rapidly halted and reversed tumor growth in about 90 percent of treated patients, but most patients' response is temporary, with tumor growth resuming in six or seven months. Investigations into how this resistance emerges have suggested that the MAPK pathway gets turned back on through activation of MEK, another protein further down the pathway. Based on promising results of animal studies, the current investigation was designed to test whether inhibiting both the BRAF and MEK proteins could delay treatment resistance.

Sponsored by GlaxoSmithKline, the study by researchers at 14 sites in the U.S. and Australia tested two of the company's drugs - BRAF inhibitor dabrafenib and MEK inhibitor trametinib, both oral medications currently being evaluated by the FDA as single-agent therapeutics - in adult patients with BRAF-expressing malignant melanoma. Phase I testing confirmed that there were no drug-to-drug interactions between the two agents and evaluated the safety of different dose combinations. In the open-label phase II portion of the study, 162 patients were randomized into three groups that received different dose combinations: two daily 150 mg doses of dabrafenib plus one 2 mg trametinib dose, the same dabrafenib dose with a 1 mg dose of trametinib, or treatment with dabrafenib alone. Participants receiving dabrafenib alone were able to cross over to the full-dose combination treatment if their cancer resumed progression.

Treatment with both combination regimens led to a significant delay - about four months longer than with dabrafenib alone - in the emergence of resistance. After one year of treatment, 41 percent of those receiving full-dose combination treatment had no progression of their cancer, compared with only 9 percent of those receiving one drug. The occurrence of side effects such as skin rash and the development of squamous cell carcinoma, a less malignant skin cancer, was similar to that typically seen when only one of the two drugs is used, and some side effects were less frequent with the combination therapy.

Noting that the tested combination, now being tested in a larger Phase III study, delayed but did not prevent resistance in most participants, Flaherty says, "We need to continue focusing on resistance mechnisms occuring with this combination approach so we can better understand how to treat patients once resistance emerges or to develop other combination regimens to further prevent relapse. We also need to see if this approach could serve as an effective adjuvant therapy used following surgery to prevent recurrence. That might have the biggest impact on patients." Flaherty is an associate professor of Medicine at Harvard Medical School.

View the Original article

Use Of Interstitial Fluid Pressure Via Noninvasive Measurement, A Potential Biomarker For Tumor Aggressiveness

Main Category: Cervical Cancer / HPV Vaccine
Also Included In: MRI / PET / Ultrasound;  Melanoma / Skin Cancer;  Cancer / Oncology
Article Date: 02 Oct 2012 - 1:00 PDT



View the Original article