Blocking mir-21 shows promise for slowing bladder cancer growth

Bladder cancer ranks among the ten most common types of cancer worldwide. The main treatment is bladder removal surgery, and despite advances in systemic therapies, recurrence is frequent in the most aggressive forms of the disease. For this reason, researchers have been seeking less invasive and more effective strategies to fight it.

A study involving the D'Or Institute for Research and Education (IDOR) and published in Biochemical Genetics points to a promising path: by blocking a small molecule called miR-21, bladder cancer cells lose their ability to multiply and spread. This discovery could pave the way for future therapies that are both less invasive and more precise.

What is miR-21 and why does it matter in bladder cancer?

miR-21 belongs to a group of molecules called microRNAs, which act as natural "switches" for our genes. They do not produce proteins directly but regulate which DNA instructions will be read or silenced, functioning like editors of the genetic code.

In the case of miR-21, when overactivated, it promotes the growth of several types of cancer-including brain, liver, ovarian, breast, prostate, and bladder tumors-mainly by silencing genes that serve as natural brakes against uncontrolled cell proliferation.

The link between miR-21 and the cancer "brakes"

In the study, researchers examined the effects of turning off miR-21 in bladder cancer cells grown in the lab. The main target was a gene called RECK, which acts as one of these natural brakes. Excessive miR-21 activity suppresses RECK, allowing tumor cells to grow unchecked and invade nearby tissues.

When miR-21 was inhibited, RECK expression increased, while levels of an enzyme called MMP9-associated with tissue degradation and tumor spread-were reduced. As a result, cancer cells lost much of their ability to migrate and form colonies, slowing down tumor growth.

In addition to laboratory tests, researchers also analyzed patient data from a public genetic database called CancerMIRNome. The results confirmed that miR-21 levels are much higher in bladder tumors than in healthy tissues. This makes miR-21 not only a promising therapeutic target but also a powerful diagnostic biomarker.

A promising future

The experiments were conducted in vitro, using immortalized high-grade bladder cancer cells. More in-depth studies in animal models and clinical trials are still needed. Nevertheless, the findings provide a solid foundation for new therapeutic approaches, particularly for aggressive cases that currently require high-risk surgeries. This represents a real hope for more effective and better-tolerated treatments for patients facing this diagnosis.