key: cord-0753036-nwuuay9y
authors: Maruta, Hiroshi; He, Hong
title: PAK1-blockers: Potential Therapeutics against COVID-19
date: 2020-04-19
journal: Med Drug Discov
DOI: 10.1016/j.medidd.2020.100039
sha: aa41cc06412ef9f765289e650aee1190b10a8455
doc_id: 753036
cord_uid: nwuuay9y

ABSTRACT PAK1 (RAC/CDC42-activated kinase 1) is the major “pathogenic” kinase whose abnormal activation causes a wide variety of diseases/disorders including cancers, inflammation, malaria and pandemic viral infection including influenza, HIV and COVID-19. Since Louis Pateur who developed a vaccine against rabies in 1885, in general a series of “specific” vaccines have been used for treatment of viral infection, mainly because antibiotics in general are ineffective for treatment of viral infection. However, it takes 12–18 months till the effective vaccine becomes available. Until then ventilator (O2 supplier) would be the most common tool for saving the life of COVID-19 patients. Thus, as alternative potentially more direct “broad-spectrum” COVID-19 therapeutics, several natural and synthetic PAK1-blockers such as propolis, melatonin, ciclesonide, hydroxy chloroquine (HQ), ivermection, and ketorolac, which are readily available in the market, are introduced here.

18 PAK1 (RAC/CDC42-activated kinase 1) is the major "pathogenic" kinase whose abnormal activation causes a wide va-19 riety of diseases/disorders including cancers, inflammation, malaria and pandemic viral infection including influenza, 20 HIV and COVID-19. Since Louis Pateur who developed a vaccine against rabies in 1885, in general a series of "specific" 21 vaccines have been used for treatment of viral infection, mainly because antibiotics in general are ineffective for treat-22 ment of viral infection. However, it takes 12-18 months till the effective vaccine becomes available. Until then venti-23 lator (O 2 supplier) would be the most common tool for saving the life of COVID-19 patients. Thus, as alternative 24 potentially more direct "broad-spectrum" COVID-19 therapeutics, several natural and synthetic PAK1-blockers such 25 as propolis, melatonin, ciclesonide, hydroxy chloroquine (HQ), ivermection, and ketorolac, which are readily available 26 in the market, are introduced here. 27 drugs, which target a specific "host" enzyme essential for viral infection, 70 but not for normal physiology of hosts, would be desirable for the COVID-71 19 treatment as well. Among such target enzymes is the major "pathogenic" 72 kinase PAK1 in hosts that is essential for malaria and viral infection in gen-73 eral [3].

Mammalian family kinases called PAKs (RAC/CDC42-activated ki-75 nases) were cloned more than 25 years ago. Among them PAK1 is the 76 major "pathogenic" kinase whose abnormal activation is responsible for a 77 wide variety of diseases such as cancers, inflammation, viral infection, ma-78 laria, immuno-suppression, ageing, and so on [3]. Among PAK1-blockers, 79 caffeic acid (CA) and its ester (caffeic acid phenethyl ester = CAPE) in a 80 bee-product called "propolis" were the first natural ingredients that were 81 shown to inhibit RAC, which activates directly PAK1 [4] . Interestingly in 82 2005, an old anti-malaria drug "Chloroquine" (CQ) was also shown to sup-83 press SARS/ coronavirus infection in cell culture with IC 50 around 1 μM 84 [5] , although the precise molecular mechanism underlying its anti-viral ac- yet, that PAK1-blockers in general could be useful for the treatment of cur-99 rent "pandemic" COVID-19 infection outbroken from Wohan in China since 100 the end of 2019, which infected over 2,000,000 people world-wide, and 101 whose death toll has reached over 120,000 people (death rate around 102 6%) till now: https://corona.help/

In addition, PAK1 is normally responsible for the suppression of im-104 mune system in hosts [9] . Thus, like viral vaccine, these PAK1-blockers 105 could boost the immune system for the production of antibody against 106 this virus as well (see Fig. 2 ). Among them the bee product called "propolis" is the most popular and 117 ancient as well. It has been used as a traditional medicine for more than 4 118 thousand years since the ancient Egyptian era. The father of medicine in an-119 cient Greece, Hippocrates, was the first to coin this bee product (an alcohol-120 extract of beehives) "propolis" ("pro" for protection, and "polis" for beehive 121 or city). Originally honey-bees extract something from young buds of trees 122 such as poplar and willow and blend the extract with their saliva to make 123 the hexagonal beehive to protect their larva from various pathogens.

Thus, propolis is a "herbal" medicine prepared by bees. It is both anti-125 bacterial and anti-viral. It is well known to be used as a mixture of antibi-126 otics for preparing mummies of deceased royal families to be stored 127 under pyramids.

In modern era, propolis was recognized as an anti-cancer medicine in 129 late 1980s by a team at Columbia University in NYC [10] . The major 130 anti-cancer ingredient in Egyptian or Israeli propolis turned out to be 131 CAPE, an ester of caffeic acid [10] which was later known to down-132 regulate RAC, thereby inactivating PAK1 [4] . Interestingly, however, the The most widely known pharmacological activity of Vitamin D3 is 303 calcemic, i.e., stimulating the absorption of calcium into bone tissues. How-304 ever, around late 1980s, a team in Melbourne found that Vitamin D3 can 305 suppress the growth of cancers in mice fed with calcium-less diet [31] . 306 However, clinically therapy of cancers with Vitamin D3 has never been suc-307 cessful. The main reason for its clinical failure is that Vitamin D3 is 308 inactivated by an enzyme called CYP24 which hydroxylates at position 24 309 of Vitamin D3 in human body.

Thus, around a decade ago, a Japanese group led by Atsushi Kittake at 311 Teikyo University in Tokyo developed a derivative called "MART-10" 312 which is very resistant to CYP24 and clearly less calcemic [32] . The 313 "MART-10" is 1000 times more effective than Vitamin D3 in human breast 314 and pancreatic cancers [32] . Interestingly, a few years ago, a German group 315 at Tuebingen University found that Vitamin D3 down-regulates RAC, 316 thereby inactivating PAK1 and leading to depolymerization of actin fila-317 ments [33] . Independently MART-10 was also found to induce the depoly-318 merization of actin in cancer cells [34] . Furthermore, CYP24 expression 319 turned out to depend on the oncogenic RAS-PAK1-NFκB/Ets signalling 320 pathway [35] . Thus, it is most likely that either "MART-10" alone or a [9] . Thus, PAK1-blockers could knock-out each virus with "double" 346 punches (Fig. 2) . Lastly it should be high-lighted that the major purpose 

A few years ago, we found that melanogenesis in 162 fact depends on PAK1 [14]. Melatonin shares a wide variety of other anti-163 PAK1 activities such as anti-cancer, immune stimulative, anti-infectious, 164 anti-inflammatory, analgestic, sleepy etc. Thus, it is almost certain that mel-165 atonin, a popular sleeping pill for jet-lag treatment, could be very useful for 166 the treatment of coronaviral infection as well. In fact, the world-leading ex-167 pert in melatonin

It was patented in 1990 and approved for adults and children 12 and 174 over by the FDA in 2006. Regarding the molecular mechanism underlying 175 its anti-inflammatory effect, it is most likely that this hormone blocks 176 PAK1, mainly for following reasons: (i) first of all, inflammation in general 177 requires PAK1 [3], and in PAK1-null mutant of mice no inflammation takes 178 place [15], (ii) ciclesonide (10 mg/kg/day) almost completely suppresses 179 the PAK1-dependent growth of lung cancer (A541 cell line) xenografts in 180 immune-deficient mice as well [16], and (iii) this hormone was recently 181 shown to block both PAK1-dependent replication and pathogenesis

Triptolide from thunder god vine and its water-solulble derivative 185 A herbal triterpene or steroid called "Triptolide "from thunder god vine, 186 a Chinese traditional medicine, was also found to inactivate RAC, thereby 187 blocking PAK1 [12]. Interestingly, more than a decade ago, triptolide was 188 found to suppress virus production during dengue virus infection of 189 human lungs by blocking PAK1 signaling pathway

Thus, several years ago, a team at University 191 of Minnesota led by Gunda George, a German organic chemist, phosphory-192 lated OH group at position 14 of Triptolide to boost its water-solubility over 193 3000 times [18]. The resultant phosphatase-sensitive prodrug of triptolide 194 called "Minnelide

Avermectin (a precursor of Ivermectin) was discovered 199 from a soil bacterium by a team led by Satoshi Omura at Kitasato Insti-200 tute in Tokyo, but it causes a side effect. Thus, to reduce its side effect, a 201 Merck team led by William Campbell chemically reduced it to develop 202 "Ivermectin

It has 204 been used to treat many types of parasite infestations including head 205 lice, scabies, river blindness (onchocerciasis), etc. 3 decades after its dis-206 covery, it was shown by a Russian team to suppress the growth of can-207 cers as well, and eventually we found that inactivation of PAK1 is the 208 major molecular mechanism underlying its anti-cancer action

Thus, it could potentially serve as an alternative (and inexpensive) ther-210 apeutic to eradicate the PAK1-dependent coronaviral infection as well

In fact, very recently Ivermectin was proven to block the COVID-19 212 infection in Vero cell culture with IC 50 around 2

the White House and NIH to use a series of PAK1 blockers including HQ for 272 the treatment of coronaviral infection, FDA quickly approved to use HQ or 273 CQ for clinical trials for COVID-19 patients in NY City, the hottest-bed of 274 COVID-19 in US. According to a French team's clinical trial for

Very interestingly, the combination of HQ and 277 another old anti-malaria drug called Azithromycin (AZ) was far more effec-278 tive than HQ alone clinically [26]. AZ is a macrolide discovered 1980 by 279 Pliva and approved for medical use in 1988

An old pain-killer called

Toradol" also could be used for the treat-289 ment of PAK1-dependent coronaviral infection. However, due to its 290 COOH moiety, its cell-permeability is rather poor (with IC 50 around 13 291 μM against A549 lung cancer cell line). Thus, via Click Chemistry (CC), 292 we have boosted its cell-permeability over 500 times (with IC 50 around 293 5-24 nM against B15F10 melanoma and A549 lung cancer cells, respec-294 tively) [29]. The resultant potent PAK1-blocker, called 1,2,3-triazolyl 295 ester of Ketorolac (15 K), suppresses both growth and metastasis of 296 chemo-resistant human pancreatic cancer xenogrfats in mice

Thus, 15 K could be used not only for pancreatic cancer therapy, 299 but also for therapy of infectious diseases caused by coronavirus

The antiviral compound remdesivir

Downregulation of Rac1 activation by 363 caffeic acid in aortic smooth muscle cells

Chloroquine is a potent inhibitor of SARS co

amodiaquine through p21-mediated suppression of T cell proliferation and Th1 cell dif-368 ferentiation

Against Ang II (Angiotensin II)-Induced Pathological Vascular Fibrosis and 371

Upregulation of the chemokine (C-C motif) ligand 2 (CCL2) via a severe acute respiratory syndrome coronavirus spike-ACE2 signaling path-374 way

Depletion of p21-activated kinase 1 (PAK1)

Preferential cytotoxicity on tumor cells by

Your Body's Natural Wonder Drug

The serum/PDGF-dependent "melanogenic" role 389 of the minute level of the oncogenic kinase PAK1 in melanoma cells proven by the 390 highly sensitive kinase assay

p21-activated kinase regulates mast cell de-392 granulation via effects on calcium mobilization and cytoskeletal dynamics

The FDA-Approved Anti

Ciclesonide Inhibits Lung Cancer Stem Cells through Hedgehog Signaling-Mediated 396 SOX2 Regulation

Differential effects of triptolide and tetrandrine on acti-398 vation of COX-2, NF-kappaB, and AP-1 and virus production in dengue virus-infected 399 human lung cells

Synthesis, Physicochemical Characterization, and Efficacy in Human

Colon Adenocarcinoma and Ovarian Cancer Xenografts

Ivermectin inactivates the kinase PAK1 405 and blocks the PAK1-dependent growth of human ovarian cancer and NF2 tumor cell 406 lines

Dihydroartemisinin inhibits growth of pancreatic 408 cancer cells in vitro and in vivo

Activation of a PAK-MEK signalling 410 pathway in malaria parasite-infected erythrocytes

Investigation of the immune-suppressive activity 412 of artemether on T-cell activation and proliferation

Sichuan pepper extracts block the PAK1/cyclin D1 414 pathway and the growth of NF1-deficient cancer xenograft in mice

FK228, a potent anti-tumor 417 antibiotic, is a novel histone deacetylase inhibitor

Signal therapy of breast can-419 abrogates the tamoxifen-resistance

Hydroxychloroquine (HQ) and azithromycin as a 422 treatment of COVID-19: results of an open-label non-randomized clinical trial

Azithromycin effectively inhibits tumor angiogenesis by sup-425

R-ketorolac Targets Cdc42 and Rac1 and Alters 428

Ovarian Cancer Cell Behaviors Critical for Invasion and Metastasis

Click Chemistry"-based highly potent PAK1-blocking 432 cancer-killer

Inhibits Both Growth and Metastasis of Human Pancreatic Cancer 435

Suppression of in vivo growth of human cancer solid 437 tumor xenografts by 1,25-dihydroxyvitamin D3

Evaluation of 19-nor-2alpha-(3-hydroxypropyl

MART-10) as a therapeutic agent for androgen-440 dependent prostate cancer

25 (OH) 2D3 Induces Actin Depolymerization in 442

Endometrial Carcinoma Cells by Targeting RAC1 and PAK1

The Vitamin D Analog, MART-10

Triple Negative Breast Cancer Cells Metastatic Potential

Regulation of rat cytochrome 447

P450C24 (CYP24) gene expression. Evidence for functional cooperation of Ras-448

Ets transcription factors with the vitamin D receptor in 1,25-dihydroxyvitamin D(3)-mediated induction