Stopping Retinoblastoma Protein May Help Treat Mesothelioma

Another molecular target for treating malignant pleural mesothelioma may have been found. So says a team of researchers from Hyogo College of Medicine in Nishinomiya, Japan.

Nothing’s certain about this yet. But the researchers say that drugs aimed at interfering with a particular type of protein found in human cells could help improve mesothelioma survival.

The protein is called retinoblastoma. The researchers said that having a lot of this protein in your cells seems to mean your mesothelioma survival chances aren’t good.

On the other hand, having little or none of this protein in your cells seems to mean your mesothelioma survival chances are a lot better.

Prevent Mesothelioma DNA from Entering New Cells

The retinoblastoma protein has long been of interest to researchers. It plays an important role in helping cells make copies of their own DNA.

Cells are supposed to copy their own DNA. They do this when preparing to split into new cells.

The copied DNA goes into the new cell. That’s great if the new cell comes from a healthy one. It’s not so great if the new cell comes from one that has mutated into mesothelioma.

The reason that’s a problem is the copied mesothelioma DNA instructs the new cell to be a mesothelioma cell rather than a healthy cell.

Then that cell copies the mutated DNA and instructs the cell it spits out to also be mesothelioma. And on and on it goes.

One way to stop a mutated mesothelioma cell from making a new mesothelioma cell is to not let it make a copy of the mutated DNA. Without that DNA copy, the new cell can’t form.

The Japanese researchers believe this could be done by somehow inhibiting retinoblastoma protein activity.

Retinoblastoma Protein Samples Examined in Mesothelioma Patients

The idea for that was tested by examining retinoblastoma protein samples from 46 mesothelioma patients who were treated between 2004 and 2012.

The protein samples came from pieces of tumor that had been taken out of each patient and then stored for future study. The median age of these patients rounds off to 60.

The researchers took each tumor sample and measured how much retinoblastoma protein it had. They gave the sample one of these grades, based on the amount of retinoblastoma protein in it:

  • Grade 0 if it had none.
  • Grade 1 if it had a little.
  • Grade 2 if it had a medium amount.
  • Grade 3 if it had a huge amount.


The researchers then looked at how long each of the 46 patients survived with mesothelioma.

It turned out that the patients who had no retinoblastoma protein in their cells had the longest mesothelioma survival. The median was 39.2 months.

The patients who had the most retinoblastoma protein had the shortest mesothelioma survival. The median for them was five months.

The study, “The Significance of RB Expression in Malignant Pleural Mesothelioma in Multidisciplinary Treatment Including Extrapleural Pneumonectomy” was published in a recent issue of the Journal of Clinical Oncology.