THE "CHELOID FACTOR" AT THE CELLULAR MEMBRANE!

We tend to be excited about intracellular pathways as they travel through the Cytosol and affect epigenetic and nuclear phenomena. And our excitement has been justified since we have been able to affect cellular life by targeting various pathway molecules.  But one should stress a particular event occurring at the membrane that mimics "wound phenomena".  Aside for providing a physical boundary of the cell, the membrane is one of the most important "organs" of the cell.  It is in itself a very chemically vibrant living "cellular tissue ".  When you start reading about the cell they tell you about the layers of proteins and lipids that make up the cellular membranes.  But this picture is far from the truth, the membrane is like the wall of a brick house.  With each brick different from the next.  Some of these bricks are called Integrins (I guess because they are an integral part of the membrane).  Some of these bricks have a Cyclin, some have a growth factor!  In fact, the membrane here serves as a reserve of these molecules. Some bricks can be divided in 2 portions.  One portion that can "FLIP" inside when needed (This portion contains the cyclin, for example) and one portion that can "FLOP" outside (this portion contains a Metalloprotease).  (see my post on FLIPPASE and FLOPPASE) The point is that once the brick is used there remains a hole with sharp edges.  These edges are called "FOCAL ADHESION Molecules" (KINASES) in a cell and are governed by the PTK2 gene!  (and of course PYK2)

PTK2:

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Protein tyrosine kinase 2
PDB rendering of the C-terminal FAT domain based on 1k04[1].
Available structures PDB Ortholog search: PDBe, RCSB [show]List of PDB id codes
Identifiers
Symbols	PTK2; FADK; FAK; FAK1; FRNK; PPP1R71; p125FAK; pp125FAK
External IDs	OMIM: 600758 MGI: 95481 HomoloGene: 7314 ChEMBL: 2695 GeneCards: PTK2 Gene
EC number	2.7.10.2
[show]Gene Ontology
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	5747	14083
Ensembl	ENSG00000169398	ENSMUSG00000022607
UniProt	Q05397	P34152
RefSeq (mRNA)	NM_001199649	NM_001130409
RefSeq (protein)	NP_001186578	NP_001123881
Location (UCSC)	Chr 8: 141.67 – 142.01 Mb	Chr 15: 73.21 – 73.42 Mb
PubMed search	[1]	[2]

PTK2 protein tyrosine kinase 2 (PTK2), also known as Focal Adhesion Kinase (FAK), is a protein that, in humans, is encoded by the PTK2 gene.^[2] PTK2 is a focal adhesion-associated protein kinase involved in cellular adhesion (how cells stick to each other and their surroundings) and spreading processes (how cells move around).^[3] It has been shown that when FAK was blocked, breast cancer cells became less metastastic due to decreased mobility.<sup>[4](Wikepedia
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AND THEY ARE PLENTY TALKED ABOUT! 
===============================================================  I.E....</sup>

"Integrin-dependent translocation of phosphoinositide 3-kinase to the cytoskeleton of thrombin-activated platelets involves specific interactions of p85 alpha with actin filaments and focal adhesion kinase(JCB)"

 

The point is that at the membrane healing should occur after the "integrin" has been plucked off, but failure to heal may trigger the "cheloid effect".  In the cell, this is where the Src gene is, the Wnt (catenins) and the Notch are here, Caspase 3 is present, and death Receptors,etc... (things can get complicated really fast with these guys around! unless of course phosphorylation or other taming mechanisms come to play!)

Focal Adhesion kinases (FAK)

". FAK is typically located at structures known as focal adhesions, these are multi-protein structures that link the extracellular matrix (ECM) to the cytoplasmic cytoskeleton. Additional components of focal adhesions include actin, filamin, vinculin, talin, paxillin, tensin^[7] and RSU-1."  This is what Taxol and Taxotere find their might!  (components of microtubules)

remember tensin is same as PTEN

NIH

" PTEN1

Also known as

BZS; DEC; CWS1; GLM2; MHAM; TEP1; MMAC1; PTEN1; 10q23del

Summary

This gene was identified as a tumor suppressor that is mutated in a large number of cancers at high frequency. The protein encoded this gene is a phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase. It contains a tensin like domain as well as a catalytic domain similar to that of the dual specificity protein tyrosine phosphatases. Unlike most of the protein tyrosine phosphatases, this protein preferentially dephosphorylates phosphoinositide substrates. It negatively regulates intracellular levels of phosphatidylinositol-3,4,5-trisphosphate in cells and functions as a tumor suppressor by negatively regulating AKT/PKB signaling pathway. [provided by RefSeq, Jul 2008]"

Secondary Hematologic Malignancies

Japanese researchers suggested in a retrospective study of patients treated with Temodar for Glioma, that there is an increased occurrence of secondary Myelodysplasia, leukemias and particularly Acute Lymphoblastic Leukemia.  It is interesting to look further, beyond the simple observation and speculate as to what leads to such a transformation at the gene level.
Leukemias are a disease not only of pathways, but of deep derangement at the Histone-DNA level and include particularly not only protein complexes similar to core binding factors, but also regulator genes which appear to be specifically amplified in leukemias!
It is pertinent to also look closer at Proteins Kinases affecting or interacting with DNA.  Temodar is an Alkylating agent per the researcher's report.
The interval between the treatment and the occurrence is also interesting, and suggests that the secondary Leukemia results from a secondary amplification of proliferative genes after the onslaught on cellular receptors by the chemical stimulus. The NK-kB, c-JUN must be in play.  Blocking these pathways could prevent such malignant occurrence. We will soon find that secondary malignancy could be prevented by simply blocking some tumor growth factors.  We don't need to accept these complications any more.  I learned that my first patient who was diagnosed with Hodgkin disease, a curable disease, died later on with an Acute Leukemia.  She was free of Hodgkin disease. Our current follow-up is inadequate in this regard, as we sit and wait for secondary leukemia to set in.  Lets look into blocking Tumor growth factors to stop secondary leukemias!

REGORAFENIB, A DEFINITIVE ADVANCEMENT IN CANCER MEDICINE!

Those of us who had treated metastatic colon cancer know that patients only dies when you have exhausted possible options. It is sobering moment to see a human being deteriorating before your eyes while you have nothing to offer!
So,  when something new comes along that appears effective, we embrace it in this disease.   We know our patients will be offered it at one given point.  Colon cancer seems to wait until you have finished all you can do!  This behavior is particular as opposed to lung cancer which appears to kill despite your doing!
The power of Regorafenib seems to reside in the number of kinases affected by this drug:VEGFR3, TIE2, PDGFR, FGFR, KIT and RET.
Through KIT, it has found its Approval for GIST.
A slew of Genes are affected by this drug (on top of those mentioned, DDR2, TrK2A, Eph2A, RAF-1,BRAF, BRAF v600E, SAPK2,PTK5, and Abl) have been included in its repertoire.

The CORRECT trial introduced us to this drug in Metastatic colon cancer.  Thumbs up!
Dose approved: 160 mg orally daily!

DDR2 has been commented on plenty here in various notes!
TrK2A seems to relate to transmembranes channel allowing survival in low K+ conditions
Eph2A is downstream the MAPK and is the feedback regulator. once activated it comes back on its membrane receptor and sens inhibitory influx to shut down the MAPK.  Cancer quickly desactivates this  to keep the signal transduction pathway on.  It kinds of remind me of the Sons of the Sevenless (my favorite).
(to be continued)

Regorafenib, the power of a good Multikinase,  the next generation Multikinase!
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RAF-1 OR c-RAF

Remember RAS-RAF-MAPK, while  c-RAF is RAF-1, people are more talking about b-RAF or BRAF.

RAF-1
"-The phosphorylated form of RAF1 (on residues Ser-338 and Ser-339, by PAK1) phosphorylates BAD/Bcl2-antagonist of cell death at 'Ser-75'.
- Phosphorylates adenylyl cyclases: ADCY2, ADCY5 and ADCY6, resulting in their activation. Phosphorylates PPP1R12A resulting in inhibition of the phosphatase activity.
- Phosphorylates TNNT2/cardiac muscle troponin T. Can promote NF-kB activation and inhibit signal transducers involved in motility (ROCK2), apoptosis (MAP3K5/ASK1 and STK3/MST2), proliferation and angiogenesis (RB1).
-Can protect cells from apoptosis also by translocating to the mitochondria where it binds BCL2 and displaces BAD/Bcl2-antagonist of cell death.
-Regulates Rho signaling and migration, and is required for normal wound healing. Plays a role in the oncogenic transformation of epithelial cells via repression of the TJ protein, occludin (OCLN) by inducing the up-regulation of a transcriptional repressor SNAI2/SLUG, which induces down-regulation of OCLN. Restricts caspase activation in response to selected stimuli, notably Fas stimulation, pathogen-mediated macrophage apoptosis, and erythroid differentiation."  (Reviewed, UniProtKB/Swiss-Prot)

Abnormality at RAF-1 causes the NOONAN and the LEOPARD syndromes,  "short stature" from genetic stand point, gives you the largest gift in genetic finding.  Again do not discriminate and round up short stature people!

SAPK-1
It is the stress induced MAPK-8 or c-JUN, block ubiquitination of P53 and therefore up-regulates it.
By involving SAPK-1, Regorafenib is indeed one of the rare drug that can impact growth factors, cyclins, TNF in a more significant way in diseases where this pathway is very amplified (from cancer to inflammatory disease and infections!)