Kevin Tharp Archives - Sanford Burnham Prebys

Tag: Kevin Tharp

Institute News

The implastic nature of plastic culture

AuthorScott LaFee
Date

November 4, 2024

Cultured cancer cells from the “immortal” HeLa human line. Image courtesy of Matthew Daniels, Wellcome Collection.
Cultured cancer cells, like these from the “immortal” HeLa human line, have proven crucial to basic cancer research. But do they accurately capture the look and behavior of living tumor cells? Kevin Tharp says no, hindering effective drug development. Image courtesy of Matthew Daniels, Wellcome Collection.

There is an art (and science) to creating cell culture models that reflect the complexities of disease. Such models have long been indispensable to parsing the underlying mechanisms of pathology and to preclinical drug discovery.

But art, writes Kevin Tharp, PhD, assistant professor in the Cancer Metabolism and Microenvironment Program, doesn’t always imitate life — at least not when it comes to finding effective cancer therapeutics.

“Just like a machine-learning algorithm trained on irrelevant datasets, efforts to discover anticancer therapeutics are limited by the models we use,” Tharp writes in the British Journal of Pharmacology. “Our drug discovery pipeline works incredibly well but is applied to models that poorly recapitulate in vivo physiology. This may be why drug discovery approaches efficiently identify drugs that work in the context tested and yet often fail to translate into clinical success.”

It’s a case of there’s no place like home. Cancer cell models are cultured on plastic in two-dimensions with limited or no diversity of neighbors. Cancer cells in vivo reside in three dimensions, with dynamic and complex interactions with neighboring cells and surroundings, i.e., the tumor microenvironment.

It’s like growing up on Disneyland’s Main Street versus a real-world urban city. Cultured cancer cells simply don’t look or behave exactly the same as cancer cells in an actual  tumor. Nor do the investigational molecules being tested as potential therapies.

Tharp suggests a multi-pronged approach: Initially culture target cells using conventional methods, then transfer the cells to new culture formats that enforce distinct, non-genomic cytoskeleton architectures and expression patterns that more closed mimic real life.

Institute News

Raising awareness of breast cancer research at Sanford Burnham Prebys

AuthorGreg Calhoun
Date

October 31, 2024

Kelly Kersten, PhD, and Kevin Tharp, PhD

The October Science Connect Series event was themed around Breast Cancer Awareness Month and featured two cancer research experts.

The Sanford Burnham Prebys Wellness Ambassadors hosted a Science Connect event on Wednesday, October 30, 2024, featuring two faculty experts discussing their breast cancer research and its implications.

The Science Connect Series provides a forum for Sanford Burnham Prebys principal investigators to share their research with administrative personnel. Faculty members gain experience in communicating their science to a lay audience, and administrators gain a better understanding of research conducted at the institute so they can become better advocates and ambassadors of the shared mission to translate science into health.

Kelly Kersten, PhD, an assistant professor in the Cancer Metabolism and Microenvironment Program, opened the event by focusing on the importance of finding new treatments —such as immunotherapies — for the one-third of breast cancer patients that are diagnosed after the early stages of the disease when surgery is less effective.

The immune system is one of the main defenses of the human body to fend off harmful pathogens and invasive cells, such as cancer. Among all white blood cells, a particular cell type, called a T cell, can directly kill cancer cells and therefore plays an essential role in building anti-tumor immune responses.

Many types of cancer are confronted and infiltrated by T cells, only to be suppressed by the local tumor environment.

“While immunotherapies that boost the immune system have revolutionized the way we treat cancer, many patients do not respond to the treatments, and the mechanisms of resistance remain largely unclear,” said Kersten.

Kersten’s goal is to understand why T cells enter a state known as exhaustion and lose their tumor-killing capacity. This knowledge will help her team find potential future therapies that could prevent T-cell exhaustion and improve immunotherapies for cancer patients.

Kevin Tharp, PhD, also an assistant professor in the Cancer Metabolism and Microenvironment Program, shared that his lab’s focus is on how cancer cells adapt their metabolism to generate the energy needed to spread to other tissues through metastasis. He presented his team’s work with the Kersten lab on another aspect of potential resistance to immunotherapy in breast cancer.

Tharp and Kersten are studying the hypothesis that part of the reason why these therapies fail is due to tumor-associated fibrosis, the creation of a thick layer of fibrous collagen (like scar tissue) that acts as a barrier against the anti-tumor immune response. They published a paper on June 3, 2024, in Nature Cancer,  discussing how tumor-associated macrophages, a type of immune cell found abundantly in the tumor microenvironment, respond to the physical properties of fibrosis.

By synthesizing injury-associated collagens that facilitate wound closure, TAMs experience metabolic changes and generate metabolic byproducts that suppress the anti-tumor function of immune cells.

“The metabolic changes in the microenvironment present more of a challenge to anti-tumor responses than the physical barrier,” said Tharp. “Our study provides an alternative explanation for why anti-tumor immunity is impaired in fibrotic solid tumors.”

To follow up on these results, Tharp is collaborating with Sarah Blair, MD, a professor of surgery at the University of California San Diego, to fund and initiate a clinical trial testing the potential of dietary supplements to counteract the suppressive effects of TAM metabolic byproducts as an adjunct therapy to surgery.

Institute News

Seminar Series: extrachromosomal DNA and the metabolic circuits of cancer immune suppression

AuthorScott LaFee
Date

March 25, 2024

A scanning electron micrograph depicts DNA circles surround X-shaped chromosomes in this colorectal cancer cell. The image is part of the first visual evidence that ecDNA is circular. Image courtesy of Paul Mischel, UC San Diego.

The ongoing Sanford Burnham Prebys seminar series will feature a pair of speakers on March 27, from noon to 1p.m., in the Fishman Auditorium. They will be presenting on two topics: extrachromosomal DNA and the tumor microenvironment.

First, Owen Chapman, PhD, a postdoctoral research scientist in the lab of Lukas Chavez, PhD, will discuss clinical and genomic features of circular extrachromosomal DNA (ecDNA) in medulloblastomas, a type of brain tumor.

EcDNA is DNA found off chromosomes, either inside or outside the nucleus of a cell. In a study published last year, Chavez (senior author), Chapman (first author) and colleagues reported that patients with medulloblastomas containing ecDNA are twice as likely to relapse after treatment and three times as likely to die within five years of diagnosis.

The second presentation will be by Kevin Tharp, PhD assistant professor in the Cancer Metabolism and Microenvironment Program. Tharp, who joined Sanford Burnham Prebys in December 2023, studies how tumors manipulate their mitochondria to improve survivability and how those cellular mechanics can be leveraged to create more effective therapies.