New Method For Detection Of Phosphoproteins Reveals Regulator Of Melanoma Invasion
Scientists have developed a new approach for surveying phosphorylation, a process that is regulated by critical cell signaling pathways and regulates several key cellular signaling events. The research, published by Cell Press in the April 10th issue of the journal Molecular Cell, describes the regulation of a... previously uncharacterized protein and demonstrates that it plays an important role in cancer cell invasion.
Many cancers, including melanoma, are associated with mutations in the gene encoding the protein kinase B-Raf. Kinases are proteins that regulate the function of other proteins by attaching a phosphate group to them. B-RAF mutations often lead to dysregulation of protein phosphorylation by the mitogen-activated protein (MAP) kinase signaling pathway. Identification and characterization of MAP kinase target proteins is critical for understanding the mechanisms involved in cancer progression.
"In contrast to targets regulated at the level of gene expression, little is known about how proteins are modified in response to oncogenic B-Raf signaling in melanoma cells. In particular, identifying cellular targets for phosphorylation is needed to gain a more comprehensive understanding of the responses to MAP kinase pathway dysregulation in melanoma," explains senior study author Dr. Natalie G. Ahn from the Department of Chemistry and Biochemistry at the University of Colorado and the Howard Hughes Medical Institute.
Current strategies to identify phosphorylated proteins require purification techniques to enrich phosphorylated from non-phosphorylated proteins and metabolic labeling procedures to quantify changes in phosphorylation. Unfortunately, these methods are not readily applied to all sample types. Dr. Ahn and colleagues developed a method for analyzing phosphorylated proteins in human cell extracts that does not depend on enrichment and can be performed quantitatively in a label-free manner.
Using their method, the researchers identified ninety phosphorylation events that were regulated by oncogenic B-Raf. The phosphorylated proteins included many known signaling molecules. However, one of the targets, MINERVA/FAM129B, belonged to a protein family with unknown function. Further investigation established a role for MAP kinase-dependent phosphorylation of MINERVA/FAM129B in cancer cell invasion within a three dimensional extracellular matrix environment.
"Our results revealed successful selection and sequencing of phosphopeptides in proteolytic digests without affinity enrichment, as well as label-free quantitation of regulated protein phosphorylation events," concludes Dr. Ahn. "Further, we demonstrated pathway-dependent phosphorylation of FAM129B and discovered its importance in controlling melanoma cell invasion."
Notes:
The researchers include William M. Old, University of Colorado, Boulder, CO; John B. Shabb, University of North Dakota, Grand Forks, ND; Stephane Houel, University of Colorado, Boulder, CO, Howard Hughes Medical Institute; Hong Wang, University of Colorado, Boulder, CO; Kasey L. Couts, University of Colorado, Boulder, CO; Chia-yu Yen, University of Colorado, Boulder, CO; Elizabeth S. Litman, University of Colorado, Boulder, CO, Howard Hughes Medical Institute; Carrie H. Croy, University of Colorado, Boulder, CO, Howard Hughes Medical Institute; Karen Meyer-Arendt, University of Colorado, Boulder, CO; Jose G. Miranda, University of Colorado, Boulder, CO; Robert A. Brown, University of Colorado, Boulder, CO; Eric S. Witze, University of Colorado, Boulder, CO; Rebecca E. Schweppe, University of Colorado, Boulder, CO; Katheryn A. Resing, University of Colorado, Boulder, CO; and Natalie G. Ahn, University of Colorado, Boulder, CO, Howard Hughes Medical Institute.
Source:
Cathleen Genova
Cell Press
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Many cancers, including melanoma, are associated with mutations in the gene encoding the protein kinase B-Raf. Kinases are proteins that regulate the function of other proteins by attaching a phosphate group to them. B-RAF mutations often lead to dysregulation of protein phosphorylation by the mitogen-activated protein (MAP) kinase signaling pathway. Identification and characterization of MAP kinase target proteins is critical for understanding the mechanisms involved in cancer progression.
"In contrast to targets regulated at the level of gene expression, little is known about how proteins are modified in response to oncogenic B-Raf signaling in melanoma cells. In particular, identifying cellular targets for phosphorylation is needed to gain a more comprehensive understanding of the responses to MAP kinase pathway dysregulation in melanoma," explains senior study author Dr. Natalie G. Ahn from the Department of Chemistry and Biochemistry at the University of Colorado and the Howard Hughes Medical Institute.
Current strategies to identify phosphorylated proteins require purification techniques to enrich phosphorylated from non-phosphorylated proteins and metabolic labeling procedures to quantify changes in phosphorylation. Unfortunately, these methods are not readily applied to all sample types. Dr. Ahn and colleagues developed a method for analyzing phosphorylated proteins in human cell extracts that does not depend on enrichment and can be performed quantitatively in a label-free manner.
Using their method, the researchers identified ninety phosphorylation events that were regulated by oncogenic B-Raf. The phosphorylated proteins included many known signaling molecules. However, one of the targets, MINERVA/FAM129B, belonged to a protein family with unknown function. Further investigation established a role for MAP kinase-dependent phosphorylation of MINERVA/FAM129B in cancer cell invasion within a three dimensional extracellular matrix environment.
"Our results revealed successful selection and sequencing of phosphopeptides in proteolytic digests without affinity enrichment, as well as label-free quantitation of regulated protein phosphorylation events," concludes Dr. Ahn. "Further, we demonstrated pathway-dependent phosphorylation of FAM129B and discovered its importance in controlling melanoma cell invasion."
Notes:
The researchers include William M. Old, University of Colorado, Boulder, CO; John B. Shabb, University of North Dakota, Grand Forks, ND; Stephane Houel, University of Colorado, Boulder, CO, Howard Hughes Medical Institute; Hong Wang, University of Colorado, Boulder, CO; Kasey L. Couts, University of Colorado, Boulder, CO; Chia-yu Yen, University of Colorado, Boulder, CO; Elizabeth S. Litman, University of Colorado, Boulder, CO, Howard Hughes Medical Institute; Carrie H. Croy, University of Colorado, Boulder, CO, Howard Hughes Medical Institute; Karen Meyer-Arendt, University of Colorado, Boulder, CO; Jose G. Miranda, University of Colorado, Boulder, CO; Robert A. Brown, University of Colorado, Boulder, CO; Eric S. Witze, University of Colorado, Boulder, CO; Rebecca E. Schweppe, University of Colorado, Boulder, CO; Katheryn A. Resing, University of Colorado, Boulder, CO; and Natalie G. Ahn, University of Colorado, Boulder, CO, Howard Hughes Medical Institute.
Source:
Cathleen Genova
Cell Press
New Therapeutic Target For Melanoma Identified
A protein called Mcl-1 plays a critical role in melanoma cell resistance to a form of apoptosis called anoikis, according to research published this week in Molecular Cancer Research.
The presence of Mcl-1 causes cell resistance to anoikis. This resistance to anoikis enables the melanoma cells to metastasize and... survive at sites distant from the primary tumor, according to Andrew Aplin, Ph.D., an associate professor of Cancer Biology at Jefferson Medical College of Thomas Jefferson University, and a member of the Kimmel Cancer Center at Jefferson. The research was conducted at Albany Medical College in New York by Dr. Aplin and colleagues.
Mcl-1 is part of the Bcl-2 protein family, and is regulated by B-RAF proteins, which are mutated in approximately 60 percent of all human melanomas. The Bcl-2 family includes several prosurvival proteins that are associated with the resistance of cancer cells to apoptosis, or cell death. Dr. Aplin and colleagues analyzed three candidate Bcl-2 proteins: Mcl-1, Bcl-2 and Bcl-XL.
"When we depleted Mcl-1 from the tumor cells, they were susceptible to cell death," Dr. Aplin said. "Mcl-1 showed dramatic results compared to Bcl-2 and Bcl-XL, which was a surprise. Our findings show that targeting Mcl-1, which is upregulated in a majority of melanoma cells, could be a viable treatment strategy."
Dr. Aplin said there are therapeutic agents in development to target this protein family, but most specifically target Bcl-2 and Bcl-XL. There is one agent in development by Gemin X Biotech that targets Mcl-1. This agent, called obatoclax, is currently in phase I/II trials.
Source: Thomas Jefferson University
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The presence of Mcl-1 causes cell resistance to anoikis. This resistance to anoikis enables the melanoma cells to metastasize and... survive at sites distant from the primary tumor, according to Andrew Aplin, Ph.D., an associate professor of Cancer Biology at Jefferson Medical College of Thomas Jefferson University, and a member of the Kimmel Cancer Center at Jefferson. The research was conducted at Albany Medical College in New York by Dr. Aplin and colleagues.
Mcl-1 is part of the Bcl-2 protein family, and is regulated by B-RAF proteins, which are mutated in approximately 60 percent of all human melanomas. The Bcl-2 family includes several prosurvival proteins that are associated with the resistance of cancer cells to apoptosis, or cell death. Dr. Aplin and colleagues analyzed three candidate Bcl-2 proteins: Mcl-1, Bcl-2 and Bcl-XL.
"When we depleted Mcl-1 from the tumor cells, they were susceptible to cell death," Dr. Aplin said. "Mcl-1 showed dramatic results compared to Bcl-2 and Bcl-XL, which was a surprise. Our findings show that targeting Mcl-1, which is upregulated in a majority of melanoma cells, could be a viable treatment strategy."
Dr. Aplin said there are therapeutic agents in development to target this protein family, but most specifically target Bcl-2 and Bcl-XL. There is one agent in development by Gemin X Biotech that targets Mcl-1. This agent, called obatoclax, is currently in phase I/II trials.
Source: Thomas Jefferson University
Gene Testing For Melanoma Risk Reduces Anxiety And Depression
People with a family history of the skin cancer melanoma show reductions in anxiety and depression after getting tested for a high-risk gene mutation, reports a study in the May issue of Genetics in Medicine, the official peer-reviewed journal of The American College of Medical Genetics. The journal is published by Lippincott Williams & Wilkins, a part of... Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals, and institutions in medicine, nursing, allied health, pharmacy and the pharmaceutical industry.
"This study provides preliminary evidence for healthy psychological, behavioral, and cognitive adjustment after participation in genetic testing for melanoma risk," according to lead researcher Nadine A. Kasparian, Ph.D., of University of New South Wales, Australia.
Who Gets Tested, and What Are the Effects?
One hundred nineteen patients were offered testing for mutation of the CDKN2A gene, which has been linked to a very high risk of melanoma. All had a strong family history of melanoma, with at least three affected relatives. A wide range of factors including beliefs about melanoma and genetic testing and symptoms of anxiety and depression were evaluated to assess the characteristics of patients who opted for genetic testing, as well as the impact of being tested.
Over a three-year period, 25 patients decided to be tested. Of these, 75 percent were found to carry the CDKN2A mutation. The researchers had expected that patients with positive test results would have at least a short-term increase in psychological distress.
To the contrary, however, patients who found they carried the high-risk gene had a significant reduction in scores for anxiety at two weeks after testing. Depression scores were also decreased, and remained so at one-year follow-up.
Several factors affected the decision to undergo genetic testing. Patients who believed they were highly susceptible to melanoma were three times more likely to be tested. In contrast, those who believed that melanoma was more likely to be fatal, even if detected early, were about half as likely to be tested. The most frequent reasons for being tested were to aid melanoma research, to learn about melanoma risk in one's children, and to learn about steps to reduce personal risk.
Behavior Changes As Well As Reduced Anxiety
People who tested positive for the high-risk gene became more likely to undergo regular skin examinations by a physician a key part of recommendations for early melanoma detection. Other behaviors, including sunscreen use, were not significantly different for people with positive tests, compared to those who decided not to be tested. Because of the small number of patients with negative gene test results, the impact of testing in this group could not be evaluated.
The genetic factors affecting melanoma risk are complex, but are coming into sharper focus with the discovery of the CDKN2A mutation and other risk genes. Although the CDKN2A test could have important benefits for people with a family history of melanoma, it has yet to come into common clinical use. Benefits of testing could include knowing one's risk and taking preventive steps, such as sun protection and skin examination. The test could also have negative effects, especially psychological distress and "fatalistic" thinking about melanoma.
The encouraging new results suggest that genetic testing for melanoma risk decreases rather than increases anxiety even for patients who discover that they have the high-risk gene. The percentage of patients deciding to be tested is lower than for other genetic tests for disease risk, perhaps because patients question the value of being tested. Dr. Kasparian and coauthors hope their results will lead to "widespread discussion of, and patient education about, the benefits, risks, and limitations" of genetic testing for melanoma risk.
About Genetics in Medicine
Genetics in Medicine is the official peer-reviewed journal of The American College of Medical Genetics. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals, and institutions in medicine, nursing, allied health, pharmacy and the pharmaceutical industry.
About the American College of Medical Genetics
Founded in 1991, the ACMG provides education, resources and a voice for the medical genetics profession. To make genetic services available to and improve the health of the public, the ACMG promotes the development and implementation of methods to diagnose, treat and prevent genetic disease. Members include biochemical, clinical, cytogenetic, medical and molecular geneticists, genetic counselors, and other health care professionals committed to the practice of medical genetics. Genetics in Medicine, now published monthly, is the official journal of the ACMG.
About Lippincott Williams & Wilkins
Lippincott Williams & Wilkins (LWW) is a leading international publisher for healthcare professionals and students with nearly 300 periodicals and 1,500 books in more than 100 disciplines publishing under the LWW brand, as well as content-based sites and online corporate and customer services. LWW is part of Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals and institutions in medicine, nursing, allied health, pharmacy and the pharmaceutical industry.
Wolters Kluwer Health is a division of Wolters Kluwer, a leading global information services and publishing company. The company provides products and services for professionals in the health, tax, accounting, corporate, financial services, legal, and regulatory sectors. Wolters Kluwer had 2008 annual revenues of €3.4 billion ($4.9 billion), employs approximately 20,000 people worldwide, and maintains operations in over 35 countries across Europe, North America, Asia Pacific, and Latin America. Wolters Kluwer is headquartered in Amsterdam, the Netherlands. Its shares are quoted on Euronext Amsterdam (WKL) and are included in the AEX and Euronext 100 indices.
Source: Wolters Kluwer Health
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"This study provides preliminary evidence for healthy psychological, behavioral, and cognitive adjustment after participation in genetic testing for melanoma risk," according to lead researcher Nadine A. Kasparian, Ph.D., of University of New South Wales, Australia.
Who Gets Tested, and What Are the Effects?
One hundred nineteen patients were offered testing for mutation of the CDKN2A gene, which has been linked to a very high risk of melanoma. All had a strong family history of melanoma, with at least three affected relatives. A wide range of factors including beliefs about melanoma and genetic testing and symptoms of anxiety and depression were evaluated to assess the characteristics of patients who opted for genetic testing, as well as the impact of being tested.
Over a three-year period, 25 patients decided to be tested. Of these, 75 percent were found to carry the CDKN2A mutation. The researchers had expected that patients with positive test results would have at least a short-term increase in psychological distress.
To the contrary, however, patients who found they carried the high-risk gene had a significant reduction in scores for anxiety at two weeks after testing. Depression scores were also decreased, and remained so at one-year follow-up.
Several factors affected the decision to undergo genetic testing. Patients who believed they were highly susceptible to melanoma were three times more likely to be tested. In contrast, those who believed that melanoma was more likely to be fatal, even if detected early, were about half as likely to be tested. The most frequent reasons for being tested were to aid melanoma research, to learn about melanoma risk in one's children, and to learn about steps to reduce personal risk.
Behavior Changes As Well As Reduced Anxiety
People who tested positive for the high-risk gene became more likely to undergo regular skin examinations by a physician a key part of recommendations for early melanoma detection. Other behaviors, including sunscreen use, were not significantly different for people with positive tests, compared to those who decided not to be tested. Because of the small number of patients with negative gene test results, the impact of testing in this group could not be evaluated.
The genetic factors affecting melanoma risk are complex, but are coming into sharper focus with the discovery of the CDKN2A mutation and other risk genes. Although the CDKN2A test could have important benefits for people with a family history of melanoma, it has yet to come into common clinical use. Benefits of testing could include knowing one's risk and taking preventive steps, such as sun protection and skin examination. The test could also have negative effects, especially psychological distress and "fatalistic" thinking about melanoma.
The encouraging new results suggest that genetic testing for melanoma risk decreases rather than increases anxiety even for patients who discover that they have the high-risk gene. The percentage of patients deciding to be tested is lower than for other genetic tests for disease risk, perhaps because patients question the value of being tested. Dr. Kasparian and coauthors hope their results will lead to "widespread discussion of, and patient education about, the benefits, risks, and limitations" of genetic testing for melanoma risk.
About Genetics in Medicine
Genetics in Medicine is the official peer-reviewed journal of The American College of Medical Genetics. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals, and institutions in medicine, nursing, allied health, pharmacy and the pharmaceutical industry.
About the American College of Medical Genetics
Founded in 1991, the ACMG provides education, resources and a voice for the medical genetics profession. To make genetic services available to and improve the health of the public, the ACMG promotes the development and implementation of methods to diagnose, treat and prevent genetic disease. Members include biochemical, clinical, cytogenetic, medical and molecular geneticists, genetic counselors, and other health care professionals committed to the practice of medical genetics. Genetics in Medicine, now published monthly, is the official journal of the ACMG.
About Lippincott Williams & Wilkins
Lippincott Williams & Wilkins (LWW) is a leading international publisher for healthcare professionals and students with nearly 300 periodicals and 1,500 books in more than 100 disciplines publishing under the LWW brand, as well as content-based sites and online corporate and customer services. LWW is part of Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals and institutions in medicine, nursing, allied health, pharmacy and the pharmaceutical industry.
Wolters Kluwer Health is a division of Wolters Kluwer, a leading global information services and publishing company. The company provides products and services for professionals in the health, tax, accounting, corporate, financial services, legal, and regulatory sectors. Wolters Kluwer had 2008 annual revenues of €3.4 billion ($4.9 billion), employs approximately 20,000 people worldwide, and maintains operations in over 35 countries across Europe, North America, Asia Pacific, and Latin America. Wolters Kluwer is headquartered in Amsterdam, the Netherlands. Its shares are quoted on Euronext Amsterdam (WKL) and are included in the AEX and Euronext 100 indices.
Source: Wolters Kluwer Health
Dark Hair? Don't Burn? Your Genes May Still Put You At Risk For Melanoma
New genetic research suggests that the traditional risk factors for melanoma may not be as helpful in predicting risk in all people as previously thought, according to data presented at the American Association for Cancer Research 100th Annual Meeting 2009.
"Traditionally, a clinician might look at a person with dark hair who did not sunburn easily and classify them as lower risk for melanoma, but that may not be true for all people in the population," said Peter Kanetsky, Ph.D., M.P.H., assistant professor of epidemiology at the University of Pennsylvania.
Kanetsky and his colleagues have identified that genetic variants in MC1R could help to predict melanoma risk in people who are not usually classified as high risk. While this link previously has been observed, Kanetsky said it is now time to begin discussing genetic factors as part of the overall melanoma risk model.
For the current study, researchers analyzed 779 patients with melanoma from the Pigmented Lesion Clinic of the University of Pennsylvania and compared them with 325 healthy control patients.
Overall, the presence of certain MC1R variants was associated with a more than two-fold risk of melanoma, but this risk was largely confined to those patients who would not usually be considered to be at elevated risk.
Although those with dark hair are not thought to be at increased risk for melanoma, if they had dark hair and also inherited certain MC1R genetic variants, their risk for melanoma increased 2.4-fold. However, no elevated risk was associated with these same MC1R variants in those with blond or red hair.
MC1R was also associated with increased risk among those with dark eye color (3.2-fold increase), who did not freckle (8-fold increase), who tanned after repeated sun exposure (2.4 fold increase) or who tanned immediately without burning (9.5-fold increase). People with these characteristics are usually thought to be at reduced risk for melanoma.
Kanetsky said a clinical screening test for MC1R is not yet available.
The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, AACR is the world's oldest and largest professional organization dedicated to advancing cancer research. The membership includes more than 28,000 basic, translational and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and nearly 90 other countries. The AACR marshals the full spectrum of expertise from the cancer community to accelerate progress in the prevention, diagnosis and treatment of cancer through high-quality scientific and educational programs. It funds innovative, meritorious research grants. The AACR Annual Meeting attracts more than 17,000 participants who share the latest discoveries and developments in the field. Special conferences throughout the year present novel data across a wide variety of topics in cancer research, treatment and patient care. The AACR publishes six major peer-reviewed journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; Cancer Epidemiology, Biomarkers & Prevention; and Cancer Prevention Research. The AACR also publishes CR, a magazine for cancer survivors and their families, patient advocates, physicians and scientists. CR provides a forum for sharing essential, evidence-based information and perspectives on progress in cancer research, survivorship and advocacy.
Source: American Association for Cancer Research
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"Traditionally, a clinician might look at a person with dark hair who did not sunburn easily and classify them as lower risk for melanoma, but that may not be true for all people in the population," said Peter Kanetsky, Ph.D., M.P.H., assistant professor of epidemiology at the University of Pennsylvania.
Kanetsky and his colleagues have identified that genetic variants in MC1R could help to predict melanoma risk in people who are not usually classified as high risk. While this link previously has been observed, Kanetsky said it is now time to begin discussing genetic factors as part of the overall melanoma risk model.
For the current study, researchers analyzed 779 patients with melanoma from the Pigmented Lesion Clinic of the University of Pennsylvania and compared them with 325 healthy control patients.
Overall, the presence of certain MC1R variants was associated with a more than two-fold risk of melanoma, but this risk was largely confined to those patients who would not usually be considered to be at elevated risk.
Although those with dark hair are not thought to be at increased risk for melanoma, if they had dark hair and also inherited certain MC1R genetic variants, their risk for melanoma increased 2.4-fold. However, no elevated risk was associated with these same MC1R variants in those with blond or red hair.
MC1R was also associated with increased risk among those with dark eye color (3.2-fold increase), who did not freckle (8-fold increase), who tanned after repeated sun exposure (2.4 fold increase) or who tanned immediately without burning (9.5-fold increase). People with these characteristics are usually thought to be at reduced risk for melanoma.
Kanetsky said a clinical screening test for MC1R is not yet available.
The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, AACR is the world's oldest and largest professional organization dedicated to advancing cancer research. The membership includes more than 28,000 basic, translational and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and nearly 90 other countries. The AACR marshals the full spectrum of expertise from the cancer community to accelerate progress in the prevention, diagnosis and treatment of cancer through high-quality scientific and educational programs. It funds innovative, meritorious research grants. The AACR Annual Meeting attracts more than 17,000 participants who share the latest discoveries and developments in the field. Special conferences throughout the year present novel data across a wide variety of topics in cancer research, treatment and patient care. The AACR publishes six major peer-reviewed journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; Cancer Epidemiology, Biomarkers & Prevention; and Cancer Prevention Research. The AACR also publishes CR, a magazine for cancer survivors and their families, patient advocates, physicians and scientists. CR provides a forum for sharing essential, evidence-based information and perspectives on progress in cancer research, survivorship and advocacy.
Source: American Association for Cancer Research
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