Tag Archives: Biochemistry

Killing the Ghosts: Beating Drug-Resistant Cancerous Cells

Rapid expansion of molecular biologists’ knowledge of how cancerous cells with damaged DNA sustain a long lifespan has helped us find new aggressive ways to wipe out cancer cells such as more effective chemotherapy. One key obstacle to tackle is the fact that cancerous cells quickly become resilient to DNA-harming medications. This leads to many chemotherapy failures.

A new research just appeared in Nature Structural and Molecular Biology  introduced an innovative method of dealing with death-evading cancerous cells by stripping these cells of their drug-resistance developing capabilities, more vulnerable to DNA damaging drugs hence.

Pancreatic cancer cells deficient in the expression of the human gene known as Schlafen 11 and resistant to chemotherapy (left panels) were re-sensitized to chemotherapeutic treatment (middle and right panels) by inhibiting the expression of the transfer RNA known as tRNA-Leu-TAA through specially designed antisense oligonucleotides. [Manqing Li, Michael David Lab, UC San Diego] (Genetic Engineering & Biotechnology News (GEN))

Built upon their prior works on HIV immunology, Professor Micheal David and Emeritus Professor Jean Wang from University of California (San Diego) say that a protein called Schlafen 11 stops the normal functions of the two vital proteins of cancerous cells, ATM and ATR. They explain that DNA damaging drugs activate Schlafen 11 which leads to cancerous cells death, and those cancerous cells which do not express Schlafen 11 simply survive the chemotherapy.  This study has a great potential for applications in immunology and virology, including HIV therapies, due to molecular mode of action of Schlafen 11.

David’s Lab further found out that, similar to the transfer RNA molecules of Schlafen 11, transfer RNA molecules of several gene families involved in DNA repair systems are encoded by transfer RNA gene rich in leucine amino acid. This provides a clue for making drug-resistant cancerous cells sensitive anew by attacking the transfer RNA molecules of DNA repair genes.

The findings show that disruption of normal functions of both ATR and transfer RNA could kill the cancerous cells combined with chemotherapy even though this technique could compromise whole DNA repair system. The paper also shows the role of cellular adjustments made in levels of transfer RNAs in survival or death of a cell with damaged-DNA for the first time.

by: Jamaledin Adel

https://www.nature.com/articles/s41594-018-0142-5?_ga=2.70392784.117150651.1540857600-2063335005.1540857600

 

Gut Bacterium Puts an End on Desperate Search for Type-O!

Long quest of the universal blood type

The idea of an ultimate universal blood type have dragged many intrigued life scientists into decades-long search for a routine productive type-O conversion. Now UBC’s Prof. Withers says his Lab made a leap towards the clinical use of universal blood group.

(Getty images; BBC )

So what is a blood type?

Since the discovery of quadruple blood types A,B, AB and O, medical scientists and a bit later immunologists have shared a long trail of hopeless struggle with the blood transfusion challenges. Recipient’s intense and potentially life-threatening immune responses are triggered by administering the incompatible blood types. The basic distinction among these blood types is the so called chemical molecules, so called markers, on the surface of the red blood cells; type-O red blood cells, however, completely lack these markers and thus could be safely transfused regardless of recipients’ blood types. In the case of type-O, the recipient’s immune system will not respond because it detects no markers on donor’s red blood cells.

(Kristine Ho;ubyssey website)

Pioneers of universal blood type

Back in 80’s, scientists took the initiative to remove those signatures from A, B and AB red blood cells, using a few enzymes, and turn these types into type-O to make it available to everyone in need particularly in emergency scenarios where there is a critically limited time to characterize patient’s blood type. The biggest obstacle, though, was impracticality and inefficacy of use of then-candidate enzyme. Besides, there was no technique for mass production of the key enzyme at the time.

And … the leap of faith!

UBC Withers’s Lab recently gained promising results by manipulating a number of common signature-removing enzymes that made the invented enzymes more robust and efficient than original ones. The new enzymes are found in a gut bacterium and was easily modified in this bug. The newly found enzymes have shown a significant competency in removing the red blood cell signatures. The last barrier to overcome is to enable this enzyme to cut out remaining forms of signatures in A and B red blood cells. Everything worked out in the laboratory, yet Withers group now looks into potential side effects and safety facets of their achievement.

by: Jamaledin Adel