Un-PAKing (PAK1-blocking) : An Evolution for
the Survival of the Fittest against COVID-19 and Many Other Biohazards.
Hiroshi Maruta, PAK Research Center, Melbourne,
Australia.
Abstract :
The "pathogenic" kinase PAK1 is
RAC/CDC42-activated Ser/Thr kinase which is present in the animal kingdom from mammals to yeasts, but
not in plants and bacteria as well as viruses.
Thus, both many bacteria and viruses need PAK1 in
hosts for their infection or pathogenesis. Very interestingly, PAK1-null mutant
of mice looks very healthy, and is clearly resistant to both inflammation and
carcinogenesis, and immune to a variety of pathogens. Furthermore, PAK1-null
mutant (RB689) of C. elegans is highly-resistant to heat shock (heating at 35oC)
and lives 60% longer than the wild-type at 20oC. Thus, it would not
be a big surprise that a series of PAK1-blockers (natural or synthetic) such as propolis extend
the healthy lifespan of C. elegans, suppress both growth and metastasis of cancers
as well as inflammatory diseases, as well as bacterial and viral infection in
mammals.
In other words, "Un-PAKing " (PAK1-blocking) is potentially an "evolutional " process of these higher organisms for "survival of the fittest" against a wide
variety of pathogens and global warming (over-heating). Thus, using these
PAK1-blockers, or just in theory knock-out (KO) of PAK1-gene in homo sapiens would lead to the birth of a
brand-new species called " homo unpaks "
which would more easily survive both the current viral pandemic and global warming.
Preface :
PAKs in amoeba and mammals
In the fall of 1974,
shortly after the world-wide « oil shock » and sudden resignation of
US President Richard Nixon due to the « Watergate » scandal, I joined Dr. Ed
Korn’s lab at NIH (National Institutes of Health) in Bethesda, outskirts of
Washington, D.C., moving by an Amtrak train across the US from Boulder in
Colorado. Three years later, in a soil (potentially pathogenic) amoeba called Acanthamoeba castellanii, I
discovered a very unique kinase called « myosin I heavy chain kinase »
(MIHCK), that became the very first step towards my life-long PAK research.
This
kinase is essential for so-called actin-activation of myosin I ATPase (1). 17
years later, Ed Manser in Singapore eventually found a very similar kinase in mammals (2),
and coined it « PAK » (RAC/CDC42-activated kinase). Among 6 distinct
PAKs, it turns out that PAK1 is the major « pathogenic » kinase which
is responsible for a wide variety of diseases/disorders such as cancer,
inflammation and bacterial/viral infection. AD (Alzheimer’s disease), hypertension,
diabetes (type 2), ageing, suppression of immune system and even melanogenesis (3).
"PAK1-null" mutant is healthier than the wild type!
The most remarkable among
phenotypes of PAK1-null mutant of C. elegans are the 60% extension of its healthy
lifespan at 20oC, and 9 times increase in heat–resistance at 35oC
(4), clearly indicating that PAK1 is responsible for both ageing and
heat-sensitivity.
PAK1-blocker (Merlin) in our own body
Around 2003, I was
contacted by a mother of 9-years old boy in Sydney who was suffering from a
rare genetic disease called NF2 (neurofibromatosis type 2). In NF2 patients, a tumor suppressor gene
called NF2 encoding a protein called « Merlin ».is missing, and
mulptiple beneign tumors called schwannoma or meningioma keep growing in brain,
causing blindness or loss of hearing, but eventually on both sides. However, so
far its only available therapy has been surgical removal or gamma-knife ray,
which often causes a side effect(s). She urged us to find a chemotherapeutic
for NF2. Well, since we had little idea as to the precise physiological function
of Merlin, we first tested the effect of Merlin on PAK1 in vitro. To our big
surprise, it directly inhibited PAK1 (5) ! In other words, in NF2 tumors PAK1 is abnormally activated as
RAS cancers in which RAS is oncogenically mutated, and thereby leading the abnormal
activation of its down-stream kinase (PAK1).
A few natural PAK1-blockers
Since RAS cancers such as
pancreatic, colon and lung cancers represent 30% of all human cancers, around
2005 we decided to start identifying PAK1-blockers in natural products readily
available in the market for "fast-track" therapy of both NF2 brain tumors and RAS cancers. The
first natural product which we found blocks PAK1 was a Chinese seasoning called
Sichuan pepper (Hua Jiao) which is used for preparation of a spicy Chinese soup
called « Marba Beancurd ». Either
70% ethanol or hot water extract of this « red » peppercorn inhibits
PAK1 in RAS cancer cells with IC50
around 10 mg/ml (6). However, so far nobody
has chemically identified the PAK1-blocking compound in this red extract.
Shortly
after, we identified a few other PAK1-blockers in bee product called « Propolis »:
Artepillin C (ARC) in
Brazillian green propolis, CAPE (caffeic acid phenethylester) in NZ and European
propolis, and Nymphaeols in Okinawa/Taiwan propolis. These propolis products
turned out to be very effective clinically for suppressing both growth and metastasis of NF tumors and
pancreatic cancers as well as infection of viruses such as Flu, HIV, and
even COVID-19 (7-9).
PAK1-blocker « Ivermectin » suppresses
COVID-19 infection !
Antibiotic called « Ivermectin »
was developed by 2015 Nobel-laureates (Satoshi Omura and Wiliam Campbell)
during late 1970s (10). Around 2007, shortly after we found that the phenotypes of Ivermectin-treated C. elegans are very similar to those of PAK1-null mutant, we proved that
it indeed blocks PAK1 in cancer cells (11). In an early 2020, a team at Monash
University in Melbourne proved that it suppresses the infection of COVID-19 in
cell culture with IC50 = 2.5 micro M (12). A few months later, its clinical trial in
US showed that this PAK1-blocker reduced the death rate of COVID-19 patients by
6 times (13).
"Chemical" evolution of PAK1-blockers
Back in late 1980s,
Vitamin D3 was found to suppress the growth of cancers in mice (14). However,
it has never been successful clinically (treatment in human cancers), mainly because
it is inactivated by an enzyme called CYP24 in human bodies which hydroxylates
at position 24. Thus, around a decade ago, a Japanese team led by Atsushi
Kittaka at Teikyo University in Tokyo developed a highly CYP24-resistant derivative
of vitamin D3 called « MART-10 » which is 1000 times more potent than
D3 in human cells (15). More interestingly, a few years ago, A German team
found that D3 is a PAK1-blocker (16).
An old pain-killer
called « Ketorolac » is a racemic mixture of R- and S-forms. S-form
inhibits directly COX-2 which is essential for synthesis of prostaglandin (a
source of pain). Interestingly, five years ago, R-form was found to block PAK1
(17). However, its cell-permeability is rather poor, mainly due to its COOH
moiety. Thus, around 2015, we developed a highly cell-permeable ester called
15K (1,2,3-triazolyl ester of Ketorolac) via Click Chemistry (CC) (18). 15K is
over 500 times more potent than Ketorolac, and suppresses both growth and
metastasis of chemo-resistant pancreatic cancer with IC50 below 0.1 mg/kg/day
without any side effect (19). Thus, both MART-10 and 15K, chemically evolved
from D3 and Ketorolac, would be the so far most advanced PAK1-blockers useful or
therapy of both cancers, NFs and viral infection such as COVID-19
pandemic.
Genetic/chemical evolution/therapy of « Noonan »
Syndrome children
There is a rare brain
syndrome called « Noonan » in which PAK1 gene is mutated to be
constitutively activated (20). This syndrome is usually disgnosed below age 10
with both frequent seizure/epilepsy and learning disability, but without any
tumors. Usually Noonan patients are short-lived, probably because they are far more susceptible to pathogenic viral/bacterial infection.
Only in theory, this syndrome
can be blocked by deletion of PAK1 gene in one of their parents' germline during in
vitro fertilization (IVF). However, in practice, it could be effectively reversed
with PAK1-blockers (UnPAKers) such as propolis and melatonin, a pineal hormone,
converting Noonan children to the far healthier/intellectual human species
called « homo unpaks ».
