Ze'ev Ronai Archives - Sanford Burnham Prebys

Tag: Ze’ev Ronai

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Ronai discusses new AI-supported breast cancer findings on Arabic-language TV

AuthorScott LaFee
Date

August 7, 2023

hand pointing to mammogram results

This month, researchers in Sweden published a study in The Lancet Oncology that compared the efficacy of artificial intelligence-supported mammogram screening versus the standard double reading by radiologists.

The researchers found in their randomized trial that AI-supported mammography screenings are safe, almost halved radiologists’ workload, and detected cancers that reviewing doctors missed.

Not surprisingly, the findings garnered international news coverage. Breast cancer is a global health threat, with more than 2.3 million women worldwide diagnosed each year and nearly 700,000 deaths.

Ze’ev Ronai, PhD, director of the Cancer Center at Sanford Burnham Prebys, was among experts interviewed by global media to provide context to the Swedish findings. He was interviewed on Alhurra, a U.S. government-owned Arabic-language satellite TV news channel that broadcasts internationally outside of the U.S.

You can watch the interview here. It’s in Arabic, but essentially Ronai said:

“This randomized trial of over 80,000 women offers an important advance for early detection of breast cancer, based on AI support of radiologist workload. AI will assist but not replace the role of radiologists in these assessments, and thus, is expected to enable radiologists to attend to more difficult cases. Caution from detections of less harmful lesions (which was one of the outcomes in this study), requires more training and careful validation. Overall, this is an important and safe advance in our quest for early detection of cancer, in this case, breast cancer.”

Institute News

Solar power gone awry

AuthorZe’ev Ronai, PhD
Date

July 29, 2019

towel on beach - sun exposure - melenoma

Are you enjoying the summer? Out grilling, swimming and hiking? Beware: those sunny days may come with a cost. 

When the sun’s rays touch your skin, they don’t stop there. Ultraviolet (UV) light enters your cells, and photons—tiny particles of light—landing on the proteins and DNA in your cells. With just the right amount of activation energy, proteins change their shape and function, and your DNA becomes damaged, or as we say—mutated. Under normal circumstances, cells use special proteins to repair mutated DNA, but when the repair proteins are damaged, DNA mutations become permanent.

Certain DNA segments called genes are more vulnerable to mutations than others. The BRAF gene, which normally makes a protein that controls cell growth, is mutated in more than 50% of melanomas—the most dangerous type of skin cancer. Melanoma appears when BRAF mutations crop up with other mutations in the same skin cell. For patients with these tumors, drugs that target BRAF and related proteins are often successful at slowing or stopping melanoma growth—but only for a while.

Unfortunately, patients who initially respond to such targeted therapy often relapse. Some patients relapse because their tumors generate a new mutation, making it resistant to the drug.  Overall, it may be only a small fraction of cells within the original tumor that develop resistance. So although 99.5% of the cancer cells in a tumor may have a mutated BRAF gene, the other 0.5% can harbor different mutations that either evolved during therapy or were present in the first place, but didn’t drive the initial tumor. For these patients, the bulk of BRAF mutant cancer cells are killed with targeted therapy, but another melanoma can evolve from the remaining 0.5%. This is why combination therapy, where drugs aim for multiple targets, are important.

But targeting every single mutation in a tumor may not be feasible. There will always be a fraction of cells with a different mutation that evolves, making patients vulnerable to a relapse. This is where attacking the tumor from another angle comes into play.  

Checkpoint immunotherapies—which have revolutionized the treatment of melanoma—attack tumors independent of their mutational makeup. They work by loosening the brakes of the immune system—brakes that normally prevent immune cells from attacking our own self. Tumors are very good at hiding from the immune system, but with the brakes released, tumors become exposed and are successfully attacked by the immune system, irrespective of their mutational makeup. 

But not everyone responds to immunotherapy—and we don’t yet know why. Is it the tumor? Is it the patient’s immune system? There is even evidence that the gut microbiome plays a role. Once we understand why some patients respond and or stop responding to immunotherapy, we can improve selection of patients for therapy, the effectiveness of these treatments and the possible combinations that work best. 

So where is skin cancer therapy headed? A combination of checkpoint immunotherapy with targeted therapies, as well as some new tricks we are learning, such as coaching tumor cells to be better recognized by the immune system, are moving the needle.

In my lab at Sanford Burnham Prebys we are dissecting the cell signals that drive cancer. Our studies are guided by data derived from patients’ tumors, coupled with advanced bioinformatics. We seek to understand how physiological processes are modified as cancer develops and how they can be exploited for cancer therapy. For example, we recently demonstrated a connection between the composition of the gut microbiome and the response to immunotherapy, establishing new paradigms, but raising important new questions. Can we better predict who will respond to immunotherapy? Can we enhance the response to immunotherapy by manipulating the gut microbiome? Can we make tumors that don’t initially respond start responding to immunotherapy? The bar is always raised, as one discovery opens so many new avenues to explore and advance our understanding, aspects that members of my lab are working hard on to answer.  

Yes—we are making progress. But preventing the initial sun exposure by using protective gear and sunscreens is needed now as much as ever.

Ze’ev Ronai, PhD, professor in Sanford Burnham Prebys’ Tumor Initiation and Maintenance Program, is a world-renowned cancer research expert and recipient of the Lifetime Achievement Award from the Society of Melanoma Research. The award recognizes his major and impactful contributions to melanoma research over the course of his career.

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What SBP Scientists are Researching to Battle Skin Cancer

AuthorHelen I. Hwang
Date

May 16, 2017

Nevus sample from Peter D. Adams' lab

Skin cancer is one of the most common of all cancers, and melanoma accounts for about 1 percent of skin cancers. However, melanoma causes a large majority of deaths from that particular type of cancer. Alarmingly, rates of skin cancer have been on the rise in the last 30 years. Here in Southern California, our everlasting summer comes with a price. Exposure to sun increases our risk to melanoma.

Melanoma occurs when the pigment-producing cells that give color to the skin become cancerous. Symptoms might include a new, unusual growth or a change in an existing mole. Melanomas can occur anywhere on the body.

At Sanford Burnham Prebys Medical Discovery Institute (SBP), we have several researchers working on the causes of melanoma and discovering new ways to treat this deadly disease.

Here is a roundup of SBP’s latest research:

Key findings show how melanoma develops in order to identify potential therapeutic targets

Ze’ev Ronai, PhD
Professor and SBP Chief Scientific Advisor

Ronai’s laboratory has been studying how rewired signaling networks can underlie melanoma development, including resistance to therapy and metastatic propensity. One player in that rewiring is a protein called ATF-2, which can switch from its usual tumor-preventive function to become a tumor promoter when combined with a mutation in the human gene called BRAF.

Ronai’s work on a protein, ubiquitin ligases, led to the identification of RNF125 as an important regulator of melanoma resistance to a common chemotherapy drug. RNF125 impacts melanoma resistance by its regulation of JAK2, an important protein kinase which could play an important role in melanoma resistance to therapy.

Work on the ubiquitin ligase Siah2 identified its important role in melanoma growth and metastasis, and its contribution to melanomagenesis. Melanoma is believed to be a multi-step process (melanomagenesis) of genetic mutations that increase cell proliferation, differentiation, and death.

Work in the lab also concern novel metabolic pathways that are exploited by melanoma for their survival, with the goal of identifying combination drug therapies to combat the spread of melanoma. Earlier work on the enzyme PDK1 showed how it can be a potential therapeutic target for melanoma treatment.

Immunotherapy discovery has led to partnership with Eli Lilly

Linda Bradley, PhD
Professor, Immunity and Pathogenesis Program, Infectious and Inflammatory Diseases Center

Bradley’s group is focused on understanding how anti-tumor T cells can be optimized to kill melanoma tumors. They discovered an important molecule (PSGL-1) that puts the “break” on killer T cells, allowing melanoma tumors to survive and grow. Using animal models, they removed this “break” and T cells were able to destroy melanoma tumors. They have extended their studies and found that in melanoma tumors from patients, T cells also have this PSGL-1 “break”. Bradley’s lab has partnered with Eli Lilly to discover drugs that can modulate PSGL-1 activity in human disease that may offer new therapies for patients.

Knocking out a specific protein can slow melanoma growth 

William Stallcup, PhD
Professor, Tumor Microenvironment and Cancer Immunology Program

The danger of melanomas is their metastasis to organs, such as the brain, in which surgical removal is not effective. By injecting melanoma cells into the brains of mice, we have shown that the NG2 protein found in host tissues makes the brain a much “friendlier” environment for melanoma growth.

Specifically, NG2 is found on blood vessel cells called pericytes and on immune cells called macrophages. The presence of NG2 on both cell types improves the formation of blood vessels in brain melanomas, contributing to delivery of nutrients and thus to accelerated tumor growth. Genetically knocking out NG2 in either pericytes or macrophages greatly impairs blood vessel development and slows melanoma growth.

Mysterious molecule’s function in skin cancer identified

Ranjan Perera, PhD
Associate Professor, Integrative Metabolism Program

Ranjan’s research uncovered the workings of a mysterious molecule called SPRIGHTLY that has been previously implicated in colorectal cancer, breast cancer and melanoma. These findings bolster the case for exploring SPRIGHTLY as a potential therapeutic target or a biological marker that identifies cancer or predicts disease prognosis.

 Drug discovery to help babies has led to a clinical trial at a children’s hospital

Peter D. Adams, PhD
Professor, Tumor Initiation and Maintenance Program

Approximately 1 in 4 cases of melanoma begins with a mole, or nevus. Genetic mutations can cause cells to grow uncontrollably. By investigating how this occurs, we can understand why melanoma develops from some moles, but not others.

Babies born with a giant nevus that covers a large part of the body have especially high risk of melanoma, and the nevus cells can spread into their spine and brain. Adams’ research identified a drug that deters the cells from growing. The drug identified will be used in a clinical trial at Great Ormond Street Children’s Hospital in London, England that may help babies with this debilitating disease.

Discovery of a receptor mutation correlates with longer patient survival

Elena Pasquale, PhD
Professor, Tumor Initiation and Maintenance Program

Pasquale’s work has included whether mutations in the Eph receptor, tyrosine kinases, play a role in melanoma malignancy. Eph receptor mutations occur in approximately half of metastatic melanomas. We found that some melanoma mutations can drastically affect the signaling ability of Eph receptors, but could not detect any obvious effects of the mutations on melanoma cell malignancy.

Bioinformatic analysis of metastatic melanoma samples showed that Eph receptor mutations correlate with longer overall patient survival. In contrast, high expression of some Eph receptors correlates with decreased overall patient survival, suggesting that Eph receptor signaling can promote malignancy.

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Ze’ev Ronai wins Lifetime Achievement Award from the Society for Melanoma Research

AuthorJessica Moore
Date

November 10, 2016

Ze've Rovai

Ze’ev Ronai, PhD, chief scientific advisor at Sanford Burnham Prebys Medical Research Institute (SBP) and professor in its NCI-designated Cancer Center, is the 2016 recipient of the Society for Melanoma Research’s Lifetime Achievement Award. The award honors “an individual who has made major and impactful contributions to melanoma research throughout their career.”

Ronai is being recognized for his significant contributions to melanoma research that are advancing understanding of this deadly form of skin cancer and could lead to new treatments. His studies on ultraviolet (UV) irradiation-induced changes that promote melanoma showed how they rewire signaling networks. A major discovery from those inquiries was that one player in that rewiring, a protein called ATF2, can switch from its usual tumor-preventive function to become a tumor promoter. Work by the Ronai lab also mapped how ATF2 contributes to melanoma development, and identified specific factors involved in melanoma response to therapy and metastatic potential.

In mapping the landscape of melanoma signaling, Ronai’s lab also uncovered the important role the enzyme PDK1 plays in melanoma development and metastasis. More recently, Ronai’s studies identified a mechanism underlying resistance of melanoma to BRAF inhibitor therapy, paving the road for a new clinical trial. Integral to Ronai’s research are translational initiatives, including the development of SBI-756, a small molecule that disrupts the complex that initiates protein synthesis and prevents melanoma resistance when combined with BRAF inhibition.

Ronai and his team also study how cancer cells thrive under harsh conditions, such as lack of oxygen or nutrients. That line of research has produced important insights into cancer heterogeneity and its capacity to drive the survival of the select few cancer cells that are resistant to therapy and able to metastasize. Ronai’s studies of proteins that control stress responses, such as Siah and RNF5, have furthered understanding of these processes and identified new targets for future therapies.

Ronai’s record of scientific accomplishments was recognized by the National Cancer Institute with an Outstanding Investigator Award, a seven-year grant that allows recipients to pursue projects of unusual potential. Ronai’s unique focus on how gene activity changes in cancer promises to continue establishing new paradigms for how cancers develop and respond to therapy.

About the Society for Melanoma Research

The Society for Melanoma Research (SMR) is an all-volunteer group of scientists dedicated to finding the mechanisms responsible for melanoma and, consequently, new therapies for this cancer. SMR contributes to advances in melanoma research by catalyzing collaborations among basic, translational, and clinical researchers, carrying new technology-based discoveries from bench to bedside and back.

About melanoma

The incidence of melanoma, the most lethal form of skin cancer, is rising at one of the fastest rates of all cancers in the U.S. Melanoma can strike people of all ages and is the most common form of cancer among young adults ages 25 to 29.

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Super-oncogenic protein that promotes development of melanoma

AuthorJessica Moore
Date

May 19, 2016

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An international collaborative study led by scientists at the Sanford Burnham Prebys Medical Discovery Institute (SBP) has identified a malicious form of a protein that drives the formation of melanoma. The findings, published in Cell Reports, reveal unexpected insight into how this lethal skin cancer develops and progresses, and may help understand and develop novel therapies against these aggressive tumors.

“We found that an inactive version of a protein called activating transcription factor 2 (ATF2) elicits a tumor-promoting effect in a way not seen before,” said Ze’ev Ronai, PhD, chief scientific advisor of SBP and professor of its NCI-designated Cancer Center. “We have known for years that the active version of ATF2 promotes melanoma, but this result was a surprise because we thought ATF2 transcriptional activity was essential to activate cancer-related genes.”

Ronai’s team has been studying ATF2’s role in melanoma for two decades. Their past work led to the view that it’s dangerous when it’s in the nucleus because it controls cancer-enabling genes, but benign when it’s not.

In the current study, researchers looked at the oncogenic potential of a ‘dead’ form of ATF2 in mice with mutations in BRAF, a kinase that transmits signals promoting cell division and is often mutated in pigmented skin cells. The same mutation is found in about half of all human melanomas.

“Inactive ATF2, in mice with mutant BRAF, resulted in the formation of pigmented lesions and later, melanoma tumors,” said Ronai, senior author of the study.

“What makes this discovery relevant to human melanoma is that we identified a structurally similar form of inactive ATF2 in human melanoma samples that has the same effects on cancer cells,” added Ronai. “Inactive ATF2 could be an indicator of tumor aggressiveness in patients with BRAF mutations, and maybe other types of cancer as well.”

“Unlike models with more complex genetic changes, like the inactivation of PTEN and p16 combined with BRAF mutations that result in rapid tumorigenesis (within a few weeks), the inactive ATF2 caused BRAF mutant mice to develop melanoma much slower, more similar to the timescale seen in patients,” commented Ronai. “This improves our ability to monitor the development of melanoma and efficacy of possible interventions.”

“We’re now investigating why inactive ATF2 so potently promotes BRAF-mutant melanoma, and looking for other types of cancer where it acts the same way,” Ronai said. “Our findings may guide precision therapies for tumors with mutant ATF2.”

The paper is available online here.

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A sugar found in seaweed may help treat skin cancer

Authorsgammon
Date

December 8, 2015

Header image

New research from scientists at Sanford Burnham Prebys Medical Discovery Institute (SBP) suggests that a rare sugar found in seaweed, mushrooms, seeds and other foods may be able to help treat skin cancer. The sugar, called L-fucose, has previously been linked to a number of pathological conditions including inflammation and certain cancers. The current study, published in Science Signaling, is the first to associate L-fucose with melanoma, the most dangerous form of skin cancer.

“Our findings offer new, unprecedented detail into the sugar’s role in cancer,” said Ze’ev Ronai, PhD, senior author and scientific director of SBP’s La Jolla campus. “We found that by tampering with L-fucose metabolism, we could inhibit melanoma tumor metastasis. Not only were the tumors affected but also their microenvironment—the cells surrounding the tumor that play a critical role in sustaining the cancer—making the discovery even more impactful.”

Sugars, such as glucose and sucrose, come from many different sources and are used by the body in unique ways. Some sugars, including L-fucose, provide crucial tags on cell-surface proteins that signal inflammation and help direct cell migration. Previous research has shown that changes in the amount of L-fucose on cells are associated with breast and stomach cancers.

The study started with a broader investigation of activating transcription factor 2 (ATF2), a protein that controls the expression of many other proteins and that has been implicated in the development of melanoma and other cancers. Ronai’s group has been studying ATF2 for more than 20 years.

“To our surprise, one of the genes found to be regulated by ATF2 was fucokinase (FUK), which controls the ability of cells to process the dietary sugar, L-fucose, into a form that is useable for the modification (fucosylation) of proteins, many of which are on the cell surface, said Ronai.”

“In human samples, we found reduced fucosylation in metastatic melanomas and a better prognosis for primary melanomas with increased fucosylation. We suspect that the absence of L-fucose on melanoma cells makes them less sticky and more mobile in the body, making them more likely to metastasize,” Ronai explained.

Importantly, in mice with melanoma, the researchers were able to increase fucosylation either by adding the sugar to their drinking water or by genetic manipulation. Both methods inhibited the growth and metastasis of the tumors.

“Many patients develop resistance to current melanoma drugs. If we can add something like L-fucose to enhance these therapies, that’s very exciting, and it’s something we’re actively looking into,” said lead author Eric Lau, PhD, who is extending studies on the role of L-fucose in melanoma at the H. Lee Moffitt Cancer Center in Tampa, Florida,

“The dietary result was especially gratifying, because it suggests that modifying fucosylation could be achieved by the simple addition of L-fucose to drinking water.

“Our results further suggest that the addition of dietary sugar may help fight melanoma by boosting numbers of helpful immune cells. We are continuing our exploration of how fucosylation and other sugar coatings affect the immune system and impact cancer,” added Ronai.

To read the paper click here

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Scientists identify promising new melanoma drug

Authorsgammon
Date

November 25, 2015

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A new drug discovered by scientists at Sanford Burnham Prebys Medical Discovery Institute (SBP) may show promise for treating skin cancers that are resistant or unresponsive to today’s leading therapies.

In the United States, 5 million people are treated annually for skin cancer, and 9,000 people die from the deadliest form—melanoma—according to the US Department of Health and Human Services.

The new compound, named SBI-756, targets a specific molecular machine known as the translation initiation complex. These structures are in every cell and play the critical role of translating mRNA into proteins. In cancer cells the complex is impaired, producing extra protein and providing a growth advantage to tumors. SBI-756 causes the translation complex to dissociate, and was shown to inhibit melanoma cell growth in the study, published today in Cancer Research.

“The unique target of SBI-756 makes it especially promising for use in combination therapy,” said Ze’ev Ronai, senior author and scientific director of SBP’s La Jolla campus. “A major issue limiting the effectiveness of current melanoma therapies is that tumors become resistant to treatment. Combining drugs that come at a melanoma from different angles may help overcome the problem of drug resistance.”

About 50% of melanomas are caused by mutations in a specific gene called BRAF. Patients with these tumors are commonly prescribed vemurafenib, a BRAF inhibitor that shrinks tumors. However, many patients experience a relapse within weeks, months, or even years because tumors evolve and become resistant to the drug. A similar phenomenon is seen in mice, where treatment of BRAF melanomas results in an initial response, but 3-4 weeks later the tumors return.

The team found that if SBI-756 is co-administered with vemurafenib, the tumors disappeared and most importantly, they did not reoccur. Even in mice with advanced/late stage BRAF driven cancer, the reappearance of . These data suggests that SBI-756 provides a significant advantage in overcoming tumor resistance.

“The ability of this compound to delay or eliminate the formation of resistant melanomas is very exciting,” said Ronai.

In other forms of melanoma, caused by mutations in the genes NRAS and NF1—which are known as unresponsive to BRAF drugs—administering SBI-756 alone significantly the scientists found. The team is now testing whether combining SBI-756 with existing drugs used for treating these types of melanomas can make the tumors disappear.

Drugs that target the translation initiation complex have been intensely pursued in the past few years, not just for melanoma, but for a wide array of cancers. SBI-756 is considered a first-in-class drug because it is the first successful attempt to target a specific part of the complex called eIF4G1.

In fact, SBI-756 is the culmination of seven years of work in Ronai’s group—testing and tweaking the drug’s features to help it bind to the target more readily and to make it easier to formulate. The resulting compound is a significant improvement over the initial version.

“It appears that the dose we need to administer is very low. Even in the experiments where the drug was administered to mice with tumors over a significant period of time, we have not found any toxicity,” Ronai said.

“The finding of SBI-756 is also exciting for the possible treatment of diseases other than cancer, such as neurodegenerative diseases, where the activity of the translation initiation complex is reported to be higher,” said professor Nahum Sonenberg of McGill University, a world renowned leader in the field of protein translation.

“We hope that we’re going to come up with the next generation of the compound that can go into clinical trials—first in melanoma but likely in other tumors,” Ronai said.

The study was performed in collaboration with the Conrad Prebys Center for Chemical Genomics at SBP, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, McGill University (Canada), the National Cancer Institute, MD Anderson Cancer Center, and Yale University.

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Sanford-Burnham researchers identify a new target for treating drug-resistant melanoma

Authorsgammon
Date

May 28, 2015

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A new collaborative study led by researchers at Sanford-Burnham, published today in Cell Reports, provides new insight into the molecular changes that lead to resistance to a commonly prescribed group of drugs called BRAF inhibitors. The findings suggest that targeting newly discovered pathways could be an effective approach to improving the clinical outcome of patients with BRAF inhibitor-resistant melanoma tumors. Continue reading “Sanford-Burnham researchers identify a new target for treating drug-resistant melanoma”

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Expanding the options to treat melanoma

Authorsgammon
Date

March 16, 2015

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Melanoma is the most deadly form of skin cancer with approximately 10,000 deaths per year in the U.S. and more than 65,000 worldwide. Although there are more and better treatment options available today than in previous years, there is still an urgent need to develop drugs that target the numerous pathways melanoma cells use to multiply, spread, and kill. Continue reading “Expanding the options to treat melanoma”

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Study explains control of cell metabolism in patient response to breast cancer drugs

Authorsgammon
Date

March 9, 2015

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A new research study has discovered a mechanism that explains why some breast cancer tumors respond to specific chemotherapies and others do not. The findings highlight the level of glutamine, an essential nutrient for cancer development, as a determinant of breast cancer response to select anticancer therapies, and identify a marker associated with glutamine uptake, for potential prognosis and stratification of breast cancer therapy. The study results were published online in Cancer Cell. Continue reading “Study explains control of cell metabolism in patient response to breast cancer drugs”