Pathways to early diagnosis

Scientists identify biomarkers that may indicate the presence of an aggressive and rarely diagnosed type of tumor in its early stages

Eduardo Geraque

A team of scientists from Hospital Israelita Albert Einstein (HIAE) and other institutions has described a series of biomarkers that may be associated with the presence of head and neck cancer, which is usually only discovered at an advanced stage and is very difficult to treat. The results, published in the journal Scientific Reports, pave the way for early diagnosis of the disease, something considered essential to a patient’s chance of recovery.

“In two tumor lineages, we found a series of microRNAs [small non-coding RNA molecules capable of regulating gene expression] that also circulate in the blood of patients with head and neck cancer,” explains Einstein Hospital biologist Patrícia Severino, who led the study. “This opens up diagnostic potential through blood tests.”

Head and neck tumors are usually detected by complex imaging tests that often require hospitalization. This type of cancer is usually diagnosed at a very advanced stage. “Depending on where the tumor is, some patients only begin to show symptoms when local metastasis has already begun,” says Severino.

Even when treatment is successful, surgery can have serious consequences. The tongue and other parts of the patient’s oral cavity often have to be removed, leading to difficulties eating, speaking, and even breathing.

The study found that microscopic structures known as extracellular vesicles carry microRNAs that could be linked to the cancer’s effect on the immune system. As potential biomarkers of this type of tumor, they could enable early and non-invasive diagnosis through a so-called liquid biopsy.

“Extracellular vesicles are responsible for various functions, even in healthy cells, primarily in cellular communication. We wanted to know if it would be possible to associate the occurrence of head and neck cancer with the content of these vesicles,” says the researcher.

Altered dendritic cells

The scientists reached their conclusions after studying two tumor lineages, one from the tongue and the other from the hypopharynx, which is at the bottom of the throat, between the mouth and the esophagus. To find out more about how extracellular vesicles help fight off cancer, they extracted them from the two tumor lineages and examined how they interact with dendritic cells, which play an important role in the immune system by expressing receptors that recognize disease-causing molecules and producing cytokines to destroy them.

Using a range of microscopy techniques, the group confirmed that extracellular vesicles from the tumors are harmful to the immune system, allowing tumors to advance. One of the tests showed that vesicles collected from the tumors were incorporated by the dendritic cells, significantly reducing their viability compared to others that were not subjected to the same treatment.

The treated cells also had a much lower migration rate, demonstrating again how vesicles from tumors can impair the functioning of cells that should be defending the body.

Finally, the dendritic cells exposed to the vesicles failed to mature, as shown by the altered expression of surface molecules CD14 and CD209, preventing them from performing their role in the immune system.

Biomarkers

The research group’s next step was to study the contents of these vesicles in an effort to determine why they were damaging dendritic cells and stopping the human immune system from fighting the cancer.

Using a molecular biology technique known as a microarray, the scientists looked inside the extracellular vesicles for microRNAs that might be regulating dendritic cells and stopping them from functioning properly.

They found 96 microRNAs in extracellular vesicles from the hypopharyngeal tumor lineage and another 68 from the tongue tumor. Of these, 31 appeared in both lineages.

One of the objectives of the research was to ascertain whether the microRNAs circulating in the blood of patients with this form of cancer are the same as those present in the tumor. The result was that 51 microRNAs from the hypopharyngeal cancer and 24 from the tongue cancer had already been detected in the blood of the patients beforehand, indicating that some of these microRNAs could one day be used as biomarkers.

“The aim is that in the future, we will be able to establish a defined set of microRNAs for which high levels indicate the presence of the tumor, with a high degree of certainty. This way clinical labs could use existing equipment to conduct tests and make early diagnoses, which would improve treatment,” says Severino.

Rinaldo Wellerson Pereira, a professor on the Graduate Program in Genomic Sciences and Biotechnology at the Catholic University of Brasília who did not participate in the research, believes the article represents an important contribution to our understanding of how tumor cells interact with the immune system.

“One positive element was the use of two tumor cell lines, which makes the data more robust,” says Pereira. “In further studies it would be interesting for the group to collect extracellular vesicles from the blood of the patients to see if the microRNAs present within them are the same as those found in the tumor vesicles and circulating freely in the blood. They could even treat dendritic cells with them to study the effects, like they did with the tumor vesicles,” he suggests.

Scientists from the São José do Rio Preto School of Medicine (FAMERP), the University of São Paulo (USP), the São Paulo State Cancer Institute (ICESP), and Heliópolis Hospital also collaborated in the study.

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