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P53 Based Treatments

Submitted by ewinter on Fri, 02/22/2019 - 10:34

P53 has been the direct target of many potential treatments over the years.  The drug Gendicine delivers wild type p53 on an adenoviral vector, and was approved by the China Food and Drug Administration for the treatment of ovarian cancer (Ayen, 2018).  Advexin, a similar drug, was blocked by the FDA in 2008 for reasons that were not officially disclosed (Osborne, 2008). However, it is known that adequate therapeutic effects for trials involving adenoviral delivery of p53 did not exist (Zeimet, 2003).  One logical explanation for this is that p53 is quite upstream in the apoptosis pathway, leaving lots of room for downstream over-amplifications or mutations that allow the tumor to evade apoptosis. There are several ongoing clinical trials in which the p53 gene is inserted via an adenoviral vector (Ayen et al. 2018).  These clinical trials represent the revitalization of p53 based gene therapy, after it was concluded to have failed over a decade ago (Zeimet, 2003).

 

PARP Inhibition

Submitted by ewinter on Fri, 02/22/2019 - 08:15

Similarly, PARP proteins (poly (ADP-ribose) polymerase) proteins are involved in multiple DNA repair processes and have been targeted through inhibition for the treatment of ovarian cancer. The PARP inhibitors that have been approved by the FDA have been shown to prevent breaks in single-stranded DNA (which have been affected by the BRCA mutation causing the onset of cancer) so that the enzyme PAR encourages the mitochondrial release of AIF; therefore leading to apoptosis of the cells affected by the cancer mutations. This therapy has been hypothesized to be combined with Bcl-2 inhibition, which is a family of proteins involved in regulating apoptotic pathways. The therapy hypothesized therapy focuses on PARP inhibition in conjunction with the increased inhibition of anti-apoptotic proteins from the Bcl-2 family, specifically BH3. The Bcl-2 inhibition therapy currently under clinical trial is the ABT-263 monotherapy, and has shown clinically significant results in competing with BH3 proteins for binding with anti-apoptotic proteins and preventing those proteins from inactivating pro-apoptotic proteins. In vitro, the combined therapy displayed increased caspase activity and encouraged the Bax/Bak apoptosis pathway (Yokohama, 2017).

BH3 mimetics

Submitted by ewinter on Fri, 02/22/2019 - 07:27

Anti-apoptotic Bcl-2 family proteins have been the subject and target of multiple ovarian cancer therapies. BH3 mimetics, small molecule inhibitors, have been designed over the years for the inhibition of anti-apoptotic proteins in an effort to induce apoptosis of cancer cells. The most potent of these inhibitors that have been successfully used are Bad-like BH3 mimetics such as ABT-737 and ABT-263. These antagonist drugs bind with high affinity to Bcl-2 and Bcl-xL in order to upregulate apoptosis.

 

Bcl-2 Protein Family

Submitted by ewinter on Thu, 02/21/2019 - 12:09

The Bcl-2 protein family consists of proteins that contain at least one evolutionarily conserved BH domain out of the four that exist (BH1, BH2, BH3, BH4).  Within this family, there exists pro-apoptotic proteins and anti-apoptotic proteins that interact to govern the fate of the cell. Anti-apoptotic proteins conserve all four BH domains, and include Bcl-2, Bcl-XL, Bcl-W, Mcl-1, and A1. Pro-apoptotic proteins can be subdivided into two groups, those with multiple BH domains such as Bax and Bak, and those with only the BH3 domain such as Bid, Bim, Bad, PUMA, and NOXA (Carter, 2016).

When the cell is not undergoing apoptosis, anti-apoptotic proteins such as Bcl-2 and Bcl-XL sequester Bax and Bak.  When the cell wishes to undergo apoptosis, the anti-apoptotic proteins are sequestered by the BH3-only pro-apoptotic proteins, releasing Bax and Bak, which allow the release of cytochrome C from the mitochondrial membrane, uncoupling the electron transport chain and inducing the activity of caspases. In healthy cells, p53 is a transcription factor for the pro-apoptotic BH3-only proteins Bik, Bid, PUMA, NOXA, as well as for Bax, the pro-apoptotic protein with BH1, BH2, and BH3 homology and the most downstream member of the Bcl-2 family in the regulation of apoptosis (Fridman, 2003). In high grade serous ovarian carcinoma, anti-apoptotic proteins including Bcl-2 and Bcl-xL are overactive and therefore responsible for keeping cancerous cells alive too long (Yokohama, 2017). Different studies have shown a negative correlation between Bcl-xL levels and drug sensitivity in regards to chemotherapy.

 

Bcl-2 Protein Family Role in Apoptosis

Submitted by ewinter on Wed, 02/20/2019 - 01:01

When the cell is not undergoing apoptosis, anti-apoptotic proteins such as Bcl-2 and Bcl-XL sequester Bax and Bak.  When the cell wishes to undergo apoptosis, the anti-apoptotic proteins are sequestered by the BH3-only pro-apoptotic proteins, releasing Bax and Bak, which allow the release of cytochrome C from the mitochondrial membrane, uncoupling the electron transport chain and inducing the activity of caspases.  In healthy cells, p53 is a transcription factor for the pro-apoptotic BH3-only proteins Bik, Bid, PUMA, NOXA, as well as for Bax, the pro-apoptotic protein with BH1, BH2, and BH3 homology and the most downstream member of the Bcl-2 family in the regulation of apoptosis.  Due to the fact that the majority of TP53 mutations present in HGSOC are in its DNA binding region, the transcriptional activation effect of p53 no longer is present for these pro-apoptotic proteins.  The major problem is that many of the BH3-only pro-apoptotic proteins responsible for inhibition of the anti-apoptotic proteins that, when active, inhibit the pro-apoptotic proteins Bax and Bak, do not get transcribed enough without functional p53. 

Bcl-2 Protein Family

Submitted by ewinter on Wed, 02/20/2019 - 01:01

The Bcl-2 protein family consists of proteins that contain at least one evolutionarily conserved BH domain out of the four that exist (BH1, BH2, BH3, BH4).  Within this family, there exists pro-apoptotic proteins and anti-apoptotic proteins that work together to govern the fate of the cell.  Anti-apoptotic proteins conserve all four BH domains, and include Bcl-2, Bcl-XL, Bcl-W, Mcl-1, and A1.  Pro-apoptotic proteins can be subdivided into two groups, those with multiple BH domains such as Bax and Bak, and those with only the BH3 domain such as Bid, Bim, Bad, PUMA, and NOXA. 

p53 in Ovarian Cancer

Submitted by ewinter on Tue, 02/19/2019 - 12:55

TP53 is the gene on chromosome 17 that encodes the p53 tumor suppressor protein.  Mutations in TP53 are present in 96% of high-grade serous ovarian cancer.  Many types of mutations in p53 have been characterized.  These include single base substitutions leading to missense or nonsense mutations and single base deletions or insertions leading to frameshift mutations or in-frame deletions or insertions.  80% of these mutations occur in the DNA binding domain, encoded by amino acid residues 102 to 292, leading to a loss of the ability to bind DNA and act as a transcription factor. Given the rate at which TP53 is mutated in HGSOC, it comes at no surprise that it is a hot target for therapy.  However, the wide range of TP53 mutations found in HGSOC present a major difficulty in TP53 targeted therapy because treatment must be specific for the mutation present. 

Comparing Figures

Submitted by ewinter on Fri, 02/15/2019 - 15:18

At first glance, the replica of the original diagram is quite accurate.  Upon further inspection, there are some noticeable differences.  The font of the text is different, so it was likely not specified.  The letters are also misplaces, for example, the C touches the bottom of the figure, whereas the B does not.  This likely means that it was done by hand.  There is a noticeable difference in leaf color in box A.  In this same box, there is a leaf from another plant overhanging the frame that is in differing orientations.  These combined observations lead me to believe that the side from which to photograph the plant was not specified.  For boxes B and C, the picture is noticeably closer to the flower in the second figure.  This could be the result of a lack of specificity, but could also be the result of measurement inaccuracies.  

 

Interspecific Interaction

Submitted by ewinter on Fri, 02/15/2019 - 12:40

This interspecific interaction is between a juniper and a forsythia.  The forsythia is surrounded by juniper, and it is clear that they are sharing the same soil.  The location of this interspecific interaction is on the west side of the Life Science Laboratories (LSL) at UMass Amherst.  Upon exiting the Integrated Science Building on the second floor, a right turn was taken, the doors to the LSL were passed, and the interspecific interaction was spotted directly in front of the single glass window that is between the LSL entrance doors and the windows looking into the laboratories. Three pictures were taken at 4 pm on a sunny day with snow covering the ground.  One picture, which included both organisms, was taken from the sidewalk, on the side farthest from the plants.   One was a top-down view of the juniper from approximately 1 foot above the plants. One was a picture of the forsythia with buds that were approximately 5 inches from the camera lens in focus, with the tan wall of the LSL in the background (no windows or juniper).  

 

Assessment of Treatment

Submitted by ewinter on Fri, 02/15/2019 - 00:38

Targeted drug delivery would be performed by creating 3 antibody binding domains for antigens CA125, KASH5, and HSF1 on a liposome. To test for the presence of these antigens in the HGSOC, we would perform an enzyme linked immunosorbent assay (ELISA) for autoantibody (AAb) reactivity.  Autoantibodies for these three antigens will be present in the blood, so ELISA will would tell us if the antibodies for these particular antigens were present. To test for treatment progression, periodic ELISA assays will be performed.  If the autoantibody levels in the blood remain high, more treatment is needed.  A possible indication of cancer evolution and/or metastasis is if less than three autoantibodies remain high.  In this event, a new liposome with only the respective two monoclonal antibodies will need to be engineered.

 

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