Why Some Cancers are Hard to Treat

In mass media, we are frequently informed about treatments to diseases like leukemia, lymphoma, and Crohn’s. But rarely do we hear: “We found a cure to cancer!” So, one may wonder: what makes curing cancer such a seemingly impossible task, and what distinguishes it from other diseases?

There is one fundamental reason why cancers are difficult to eradicate: these cells adapt and evolve in response to treatment (Fodale, Pierobon, Liotta & Petricoin, 2011). Thus, even if a treatment is initially effective, its impact starts to dwindle, since the biological components that it blocks eventually “re-wire” themselves to circumvent the treatment (2011).

Chemotherapy – a method of using drugs to attack malignant (harmful) cells – is performed on 67% of all cancer patients (“Chemotherapy,” 2014). Yet, these

Figure 1. According to the diagram, tumor blood vessels have a squiggly or nonlinear path, unlike normal blood vessels, which is evidence of their highly abnormal tumor vasculature. In addition, the lack of the orange patches at the edge of the vessel represents the lack of supporting cells, caused by its hyperpermeable structure (Wilson & Brown, 2004).

drugs can be resisted by cancer cells (“House call: What is metastasis?,” 2016). For example, studies conducted by a group of scientists at the MD Anderson Cancer Center, which participates in therapeutic clinical research exploring novel treatments for cancer, show that cancer cells can travel to different parts of the human body, known as metastasis (2016). This makes it especially difficult to track down cancer cells and prevent them from spreading (2016). However, scientists have found that cancer cells use a protein called PGC-1a, which helps form new mitochondria, used to harness energy (Tan etal., 2016). Using this energy, they metastasize to different parts of the body and find a new home to live in, making it hard for scientists to track them down (2016).

Tumor cell expansion is further proliferated by its uncontrolled growth (Eales, Hollinshead & Tennant, 2016). Scientists have found that the deformed tumor blood vessels cause regions of hypoxia or oxygen-deprived conditions (2016). Hypoxia – a condition in which the body is deprived of adequate oxygen supply – arises in tumors through the rapid proliferation of cancer cells, which causes the tumor to exhaust the nutrient and oxygen supply from the normal blood vessels (2016). However, the tumor-proliferating effects of hypoxia cannot be generalized because they can either have detrimental or beneficial effects depending on severity, duration, and context (2016).   

Yet there are even more ways that cancer cells can adapt: they manipulate an enzyme called PKM2 (Prescott, 2011). By keeping PKM2 levels low, the cancer cells channel incoming glucose to metabolic pathways that generate antioxidants, thereby surviving oxidative stress, the imbalance between the production of free radicals and the ability of the body to counteract their harmful effects (2011). Thus, it is hard for scientists to investigate PKM2 manipulation by cancer cells (2011).

Despite the adaptive nature of cancer, oncologists are continually learning more about cancer cells (Evan, 2014). For example, professor Gerard Evan, head of the Department of Biochemistry at the University of Cambridge, is studying the genes that drive the development and growth of cancer, called oncogenes (2014). To combat the disease, Evan uses genetically engineered mice, which enable him to toggle on and off tumor suppressor genes (2014). This allowed scientists to identify the most effective therapeutic targets and employ a range of molecular biology technologies to address roles played by key oncogene signaling pathways in the genesis and progression of cancers (2014). These technological advancements help develop effective treatments to combat the adaptive nature of cancer in the future.

References

 

How Did Life End Up on Earth?

By Ashley Indictor

Is Earth the only planet in the universe that contains life? Scientists and philosophers for millennia have debated how life developed on Earth, coming up with several hypotheses and theories. One possible explanation is the theory of panspermia, in which a comet or other celestial body brought life to Earth (Hardy, 2014).

Figure 2. Microscopic view of a tardigrade (Pickett, 2015)

As far as we know, no other moon or planet in our solar system (i.e., the Sun, its planets, their moons, and all asteroids, comets, and rocks) has life on it. Although moons like Titan and Enceladus could harbor life (simple organic life forms), and Mars is theorized to have once supported life, Earth is the only planet in the Solar System we can call “living” (NASA, 2017). About 4 billion years ago, Earth underwent a period of heavy bombardment where it was barraged with asteroids and comets (Kaufman, 2017). The earliest evidence of life on Earth dates back 3.83 billion years, coinciding with the period of such violent event (2017). One explanation for this eerie overlap is that one or more of these millions of comets and asteroids carried life from somewhere else and brought it to Earth when it crashed on the surface (2017).

It is not too far-fetched to believe that these lifeforms survived space’s harsh climate. After all, some organisms on Earth can survive temperatures as low as -18°C and as high as 113°C, even after being preserved in liquid nitrogen at -196°C (Joshi, 2008). Tardigrades (see Figure 2), for instance, can live in these extreme temperatures, and can even survive many days at low Earth orbit while being exposed to a space vacuum and harmful radiation (Bradford, 2017). Tardigrades are living proof that life can be carried across space and survive until it reaches a celestial body. This further indicates the possibility of life coming from somewhere else.

Figure 3. Bacterial spore (National Academy of Sciences, 2018)

An additional consideration is that bacteria could have entered Earth through bacterial spores [see Figure 3], as they can survive without nutrients (Joshi, 2008). Bacterial spores have protective bodies that allow bacteria to carry DNA while withstanding conditions that would normally kill them (Cornell, n.d.). Furthermore, bacteria are famous for their ability to survive in extreme conditions and even campuses about one-third of Earth’s biomass (total mass of organisms on Earth) (Joshi, 2008). The German Aerospace Centre found that it is possible bacterial spores can travel within comets or meteorites (2008).

Overall, we still do not know the true origin of life. While the theory of panspermia is possible, more research must be conducted to reach an answer. Perhaps it will take another thousand years before we figure it out.

 

References:

  • Bradford, A. (2017). Facts about tardigrades. Retrieved November 26, 2017, from https://www.livescience.com/57985-tardigrade-facts.html
  • Cornell. Bacterial endospores. (n.d.). Cornell University. Retrieved February 17, 2018, from https://micro.cornell.edu/research/epulopiscium/bacterial-endospores
  • Hardy, D. A., [digital image]. (2014). The Late Heavy Bombardment ends: Impact events. Retrieved April 30, 2018, from http://www.bbc.co.uk/science/earth/earth_timeline/late_heavy_bombardment
  • Joshi, S. (2008). Northwestern University. Retrieved November 26, 2017, from https://helix.northwestern.edu/article/origin-life-panspermia-theory
  • NASA astrobiology. (n.d.). NASA. Retrieved November 26, 2017, from https://astrobiology.nasa.gov/news/in-search-of-panspermia/
  • Pickett, R. [digital image] (2015). National Geographic. What the world’s toughest animal is
  • really made of. Retrieved May 14, 2018, from https://news.nationalgeographic com/2015/11/151128-animals-tardigrades-water-bears-science-dna/
  • Smith, C. [digital image] (2017). National Geographic. These ‘indestructible’ animals would survive a planet-wide apocalypse. Retrieved April 30, 2018, from https://news.nationalgeographic.com/2017/07/tardigrades-water-bears-extinction-earth-science
  • National Academy of Sciences. [digital image] (2017). National Academy of Sciences Retrieved on April 30, 2018, from http://m.pnas.org/content/106/46/19334/F1.expansion.html
  • Solar System exploration: In depth. (2017). Nasa.gov. Retrieved from https://solarsystem.nasa.gov/moons/saturn-moons/in-depth/

Dogs And Us

By Samantha Sabah via Tech Science Times

Dogs are often called man’s best friend, and there’s a good reason why. Dogs and humans share a long history together, especially since dogs are one of the first animals humans have ever domesticated (Fogle, 1995). Dogs have adapted to their “new” companionship with humans, for better or worse.

Thousands of years ago, dogs didn’t exist; the most similar animal to a dog back then was the wolf, which is now the dog’s closest relative (1995). The similarities between dogs and wolves are evident, noted in their abilities to form relationships, natural instincts to form a social hierarchy, and similar anatomical structures (1995). These features give us a hint as to why the wolves came to be domesticated by humans. Wolves hunt when they need to, but at their core, they are scavengers, and were tempted by the scraps found at prehistoric human campsites (1995). These campsites lured them to areas with less competition, fewer predators, and a more stable supply of food (1995). As wolves were increasingly drawn into the human sphere, those that were smaller and more sociable thrived, and overtime only these wolves lived around people, with each generation after them shrinking in size and being naturally friendlier (1995). These changes are considered part of natural selection, since we did not directly manipulate the genetics of these now domesticated “dogs”; they naturally evolved into the best traits based on their new environment (1995). However, after this, we took advantage of this natural process and started to selectively breed these dogs, who, over time, became more diverse from wolves and even others of their kind (1995).

The most significant differences between modern day dogs and wolves may not be apparent. Most of the time, people obtained the traits they wanted by breeding dogs who displayed them. Some traits were emphasized, phased out, or kept based on the roles people wanted their canine companions to perform. For example, the act of barking isn’t usually seen in grown wolves. This trait was extended into adulthood for dogs to warn their humans of possible dangers. Their “pack mentality,” enhanced senses, and ability to hunt in a team made them great guards and hunting companions for us. This development has occurred around the world, even in isolated areas like the Americas (1995). It can be said that dogs were seen as companions during more ancient and less modern times as well; throughout the centuries these loyal animals have provided us comfort, especially since they themselves seem to enjoy spending time with us. However, this particular behavioral trait wasn’t as important to people as it is now.

Back then, dogs weren’t typically bred for looks. They were designed for efficiency and health to get the most work out of them. It wasn’t until the 1800s with the

A diagram of the bulldog’s squished face structure (“Bruiser”, n.d.)

introduction of dog shows did people start to care about what breed of dog they acquired and what they should look like. According to The Encyclopedia of Dogs, the Kennel Club that was created in England in 1873 (1995) started to regulate the types of dogs allowed in these highly popular dog shows. This started a new precedent by specifically identifying canines by breed. After the club set up guidelines for how certain traits should look on certain dogs in order to win contests, the most severe of modern genetic defects in dogs began to take form. As a result, inbreeding for these traits then weakened breeds as a whole. If humans didn’t continue to interfere with nature, these traits would have been phased out, unable to compete with healthier specimens. Now, there is a number of dog breeds that suffer from a lack of genetic variety in more beneficial traits. The best example for this phenomenon is seen with the English bulldog (see figure 2). Bulldogs were traditionally bred to attack bulls, but the “breed-club standards emphasized the size of the head.”(1995). This led to problems during birth because their heads were unable to fit through their mother’s birth canal. Unfortunately, this isn’t the only possible problem. Its elongated palate, or roof of the mouth, causes breathing and heart problems; its crowded teeth can lead to oral diseases, and the excessive skin folds are vulnerable to infections (1995). That isn’t to say we should just let the bulldog, or any other breed, die because of possible ailments, just that breeders have to be careful while breeding since it could lead to huge health problems in the offspring. Another possible solution might include crossing these dogs with different breeds who don’t share similar diseases, thus reducing the chance of a detrimental gene getting passed on.

Looking around at all the dogs that have filled a niche in our society, every single one of them has had their lives shaped by humans. Dogs rely on us, and we love them, but is breeding them for “special” features that ultimately can make them very sick properly conveying our love? Does breeding have to contain the risk of genetic defects? Humans have been breeding healthy canines for millennia, and our growing understanding of DNA can only aide what we know is beneficial. We can help our furry brethren long into the future.

References

  • Andrews, B. J. (n.d). [digital image]. How dogs changed human evolution. Evolution of Meat Eaters. Retrieved December 4, 2017, from http://www.thedogplace.org/Genetics/Dogs-Changed Evolution_Andrews-08.asp
  • Wysong, M. & Wysong, E. (n.d). [digital image]. Why the overdone, heavy wrinkled bulldog is killing the breed. BruiserBullDogs.com. Retrieved December 4, 2017, from http://bruiserbulldogs.com/why-the-overdone-heavy-wrinkled-bulldog-is-killing-the-breed/
  • Fogle, B. (1995). The encyclopedia of the dog. London: Dorling Kindersley Limited.