Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Common molecule notifies immune system of prostate cancer

In experiments with mice, researchers have found that the body’s immune system can use a surprisingly common molecule to recognize prostate tumors. The molecule comes from a protein found in all cells of the body; however, immune cells appear to respond to it only when it is present on the surface of cells within a tumor.

Understanding how this protein, known as histone H4, signals the immune system to respond to malignant cells may help researchers refine immunotherapy strategies that harness the body's own immune system to fight tumors. Some types of immunotherapy are already being tested in patients, but many questions remain unanswered. In particular, researchers want to know if tumor cells display molecular signposts that tell the immune system, “I'm a cancer cell, destroy me.”

Howard Hughes Medical Institute investigator James P. Allison and his team report finding one such signpost in prostate tumors in mice. The finding points toward possible improvements in immunotherapy.

“We know very little about how the immune system responds to tumors, especially early tumors,” said Allison, director of the Ludwig Center for Cancer Immunotherapy at Memorial Sloan-Kettering Cancer Center in New York. “Is the tumor at that stage invisible, or can immune cells detect it? And if they can detect it, can they mount a response? Those are the two big questions.”

Allison's research, published in the January 11, 2008, issue of Science, found that immune cells can, in fact, detect prostate cancer, at least in lab mice. However, the immune system mounts only a feeble attack against the tumor.

But the signpost Allison's team identified might make revving up that feeble response much easier.

The strategy relies on a specific type of immune system cell called a killer T cell. Each of these cells bristles with thousands of receptors that recognize molecules that do not belong in the body. When a T cell recognizes a foreign molecule, it tries to destroy the cell carrying it. The T cell then replicates, making copies that also latch onto the same foreign molecule.

In 1982, while at the University of Texas at Austin, Allison discovered T cell antigen receptors, the fork-like proteins that recognize the molecular signals on invading cells. Each T cell has a different receptor as determined by genetics and a random process. There are trillions of different T cell receptors possible, a number greater than the number of cells in the human body.

In normal tissue, the distribution of receptors found on T cells is random. That is, a batch of T cells will have a range of receptors, with none being more common than the others.

But in the new work, one of Allison's colleagues, Peter Savage, discovered that the cancerous prostate glands of mice harbored many T cells carrying a specific receptor. That meant that a single T cell had recognized the malignancy and had replicated.

Savage found the overrepresented receptor in 15 of 20 mice with prostate cancer. “That told us something was going on,” said Allison. “You don't see this in normal mice.”

At this point, the team knew that the immune system of the mice was recognizing a particular signpost of malignancy. But they had no idea what the signpost was.

“The obvious question was, ‘What are these T cells seeing?’” said Allison. “And that's when the hard work started.”

The team chopped up tumor cells in a dish and mixed them with antigen presenting cells and T cells carrying the receptor they had identified. The T cells switched on, which “showed we had really gotten the right receptor,” said Allison. However, during control experiments, the team also found that nearly any type of tissue, if it was chopped up, would activate the T cells.

“This started some head scratching,” said Allison. Because if every tissue activated the T cells, it meant that the signpost was not specific to the cancer cells.

The mystery deepened when mice were engineered to produce T cells that carried only the receptor of interest. Those cells did not attack every tissue. They only attacked – albeit feebly – the prostate tumors. It was a conundrum.

Returning to their experiments in the lab dish, the team decided to focus on specific parts of the tumor cells. They soon discovered that only molecules from the nucleus activated their T cells.

“This was really a surprise, because normally, nuclear proteins don't get fed onto the cell surface,” said Allison. And in living animals, T cells only recognize molecules on the surface of other cells – they can't peer deep into the nucleus.

The team then searched for particular nuclear proteins that activated the T cells. They eventually struck on histone H4. As the wrapper that sheaths the DNA inside all cells, histones are abundant in the nucleus. The finding explained why the normal cells, when chopped up, had activated the T cells – their histones were being exposed.

The team had identified the molecular signpost that activated the T cells, but they had also landed on another big question – how do the histones rise to the surface of the tumor cells. “Every cell has a ton of histone, and we just don't know why the tumor cells put it on their surface,” said Allison.

The team is now examining the blood of patients with prostate and other cancers to see if people, like mice, carry T cells sensitive to histone. If so, “then we can take those cells out and try to activate them,” said Allison. “Those cells already recognize the tumor. If we can mobilize them, maybe it will have a therapeutic effect.”

Allison and his colleagues are also conducting studies to determine whether the presence of histone H4-reactive T cells in the blood could be used as a diagnostic marker for the early detection of prostate cancer.

Jennifer Michalowski | EurekAlert!
Further information:

More articles from Health and Medicine:

nachricht Resolving the mystery of preeclampsia
21.10.2016 | Universitätsklinikum Magdeburg

nachricht New potential cancer treatment using microwaves to target deep tumors
12.10.2016 | University of Texas at Arlington

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>