Research identifies bacteria in pancreas tumor that can help in diagnosis

Researchers at the Rutgers Cancer Institute in New Jersey (USA) have developed a tool capable of mapping the microbiota found in a type of pancreatic cancer, pancreas duct adenocarcinoma (PDA), to assess whether the tumor is evil or not. The research was published last Monday (10) in the specialized journal Cancer Cell.

Pancreatic cancer is considered the fourth leading cause of cancer death in both men and women in the United States. In Brazil, despite only accounting for about 2% of all cancer cases, the adenocarcinoma type in the organ is the most common (about 90% of diagnoses) and has a high lethality, according to data from the Ministry of Health.

To investigate which microorganisms live together with pancreatic cancer, the scientists sequenced the DNA present in the tumor cells and isolated the human DNA (which represents the host) from that of the so-called microbiota, a set of microorganisms that inhabit the organ.

From the “clean” sequences of genetic material, that is, without other components that could interfere with reading, the researchers observed the frequency of these bacterial DNA fragments in 55 adenocarcinoma samples obtained from two well-studied groups of cancer patients in the United States. .

The sample included 41 patients with malignant tumors and 14 who had the benign form and had the tumors removed by surgery.

Using a computer program to map whether the cell pools and the presence of the microbiota’s DNA sequences “matched”, the scientists observed that 48 of the 55 samples (87%) tested positive for bacterial genetic material, which included at least least 19 distinct genera of bacteria.

However, although these bacteria were present in most of the samples, 18 types were found in cells from the malignant tumor samples and only one type was present in the benign tumor.

Next, the researchers took samples from 13 healthy individuals (with no history of cancer) and looked for genetic material from bacteria associated with pancreatic cells, but did not get any positive results.

In the analysis, it is not possible to know if the presence of bacteria is associated with some type of interaction between the pancreatic tumor and these microorganisms, or if the presence of cancer together with other underlying conditions (gastrointestinal diseases) can lead to their appearance. However, other studies have already demonstrated an association between bacteria and other microorganisms and tumor cells.

In reply to Sheet By email, genetic engineer and senior author of the study Subhajyoti De said that it is not possible to rule out the possibility that these bacteria found were derived from other diseases, but that the healthy samples had a very low amount of microorganisms, making this hypothesis less likely.

“Some of the microorganisms seem to have a very strong affinity for tumor cells, so most genera [18 de 19] appeared in malignant tumor samples, but future studies may help to better answer this question,” he said.

For him, the science that investigates the association of microbiota with tumor cells is something particularly new, but with great potential for both diagnosis and treatment. “The so-called ‘fingerprint’ that these microorganisms leave on cells or in the bloodstream can be easily analyzed in blood samples in the laboratory, and this makes it possible to diagnose and analyze cancer progression in a non-invasive way.”

Regarding treatment, it is still too early to know if a therapy with any antibiotic can help or hinder the treatment of cancer, and even if these bacteria benefit from the tumor or are just coexisting. The research by De et al., however, found a strong association of cells of the immune system, the so-called T lymphocytes, in tumor cells that had bacterial DNA.

“It may be that this association with T lymphocytes is indicating a relationship of these microorganisms with the body’s defense mechanisms against the tumor, but there is still no discovery in this regard. There are studies investigating the clinical outcome of patients who are treated with associated immunotherapics with antibiotics, but nothing yet about pancreatic cancer. Further research can explore this therapeutic window”, he adds.