Tumor cells engineer acidity to drive cell invasion

[Celebration]

http://medicalxpress.com/news/2013-01-tumor-cells-acidity-cell-invasion.html

Researchers at Moffitt Cancer Center and colleagues at Wayne State University School of Medicine investigated the acidity in solid tumors to determine if pH levels play a role in cancer cell invasion in surrounding tissues. They found that an acidic microenvironment can drive cancer cells to spread and propose that neutralizing pH would inhibit further invasion, providing a therapeutic opportunity to slow the progression of cancers. google_protectAndRun

Their study appeared in the Jan. 3 online release of Cancer Research, a publication of the American Association for Cancer Research. According to the study's corresponding author, Robert J. Gillies, Ph.D., chair of the Department of Cancer Imaging & Metabolism at Moffitt, acidity in solid tumors is the result of an increased fermentative metabolism combined with poor delivery of blood to tissues. In this study, tumor invasion and pH were monitored in immunodeficient laboratory mice hosting a variety of tumors.

"We monitored the test animals over time using microscopy and found that the highest regions of tumor invasion corresponded to areas with the lowest pH," Gillies explained. "Tumor invasion did not occur in regions with normal or near normal pH levels. Furthermore, when we neutralized the acidity with oral sodium bicarbonate, the invasion was halted."

Researchers proposed that the acidic pH of the tumor microenvironment represents a "niche engineering" strategy on the part of tumor cells, promoting invasion and growth of malignant tumors into surrounding tissue. Niche engineering is a concept in ecology describes how plants and animals alter their environment to in ways that promote their own growth and survival over their competitors. "We have long regarded cancers cells as an invading species," said study co-author Robert Gatenby, M.D., chair of the Diagnostic Imaging Services and Integrated Mathematical Oncology departments at Moffitt. A key to this process of adaptation and invasion is increased glucose metabolism in the tumor. "The vast majority of malignant tumors metabolize glucose at high rates," Gillies said. "We have proposed that there is a direct, causative link between increased glucose metabolism and the ability of cancer cells to invade and metastasize."

[KT2000]

1. yes - this is why people with cancer

will often adopt the macrobiotic diet.
Good to see they are catching up.

[flamingdem]

2. "Tomatoes are inedible"

Michio Kushi

[2on2u]

3. This fellow would probably agree with you....

[NickB79]

4. Oral sodium bicarbonate?

"We monitored the test animals over time using microscopy and found that the highest regions of tumor invasion corresponded to areas with the lowest pH," Gillies explained. "Tumor invasion did not occur in regions with normal or near normal pH levels. Furthermore, when we neutralized the acidity with oral sodium bicarbonate, the invasion was halted."

Taking bicarbonate orally won't lead to a lowering of your body's overall acidity; the bicarb is neutralized by stomach acids and doesn't enter the bloodstream. And if you did lower a body's acidity that much, you would kill the lab mice used in the study through hypoacidity.

Since they are talking about the micro-environment found inside a tumor, are they rather stating that they injected a solution of sodium bicarbonate into it to neutralize the acidity? This is a very important point that wasn't fully addressed in the statement.

[Celebration]

5. Yes, the blood pH always stays the same

But I don't think they are talking about blood pH. And yes, he just added sodium bicarbonate to water the mice drank. He didn't measure pH by doing blood work, but with imaging techniques (as I understand it).

Here is the description.

http://www.moffitt.usf.edu/research--clinical-trials/partnerships--studies/physical-science-oncology-center/physical-science-oncology-center-ps-oc-project-2

The PI has investigated the physical microenvironment using a wide range of imaging techniques. This work has clearly demonstrated that chronic and acute (often cyclical) hypoxia exists in most tumors in vivo and that the extracellular pH of tumors is highly acidic while the intracellular pH typically remains in the normal range. A number of observations have these changes in the physical microenvironment significant affect tumor growth. For example, tumor cells exposed to hypoxia or acidosis in-vitro or in-vivo are far more invasive and metastatic. Clinical tumors that have high glucose uptake have a poorer prognosis than those with lower uptakes. One reason for this may apparent at the tumor-host interface. Although tumors are often considered as isolated systems, they are in direct contact with adjacent normal tissue. This interface allows interactions of the physical microenvironment so that the acid in tumors can flow down concentration barriers into adjacent normal tissue producing regional acidosis. The acid-mediated invasion model proposes this acidification promotes tumor invasion by inducing proteolysis of the extracellular matrix, inducing death of normal cells, inhibiting immune response, and promoting angiogenesis. A recent test of this hypothesis examined the effects of increasing systemic buffering by adding sodium bicarbonate to the water of tumor bearing mice. Initial analysis with mathematical models suggested that this could reduce the intra- and peri-tumoral pHe sufficiently to reduce tumor invasion. Experiments in tumor-bearing mice demonstrate a significant reduction in tumor metastases in the animals receiving sodium bicarbonate.