Peutz-Jeghers Polyposis and the LKB1 Tumor Suppressor

The Peutz-Jeghers Syndrome is a rare cancer predisposition condition, caused by mutations inactivating the LKB1 tumor suppressor kinase. This study aimed to further the understanding of this disease, provide potential means of treatment to Peutz-Jeghers patients, and to add to our understanding of cancer formation in general. These aims were pursued through exploring the molecular functions of the LKB1 kinase, studying the tumor formation upon loss of LKB1 function, and through intervening with this tumor formation process. The study was mainly performed in the Lkb1 knockout mouse or derived tissues and cells, but partly also with Peutz-Jeghers patients and patient materials. We found that the LKB1 kinase phosphorylates and thereby activates 13 kinases in the AMP-activated kinase family, any of which could putatively relay the tumor suppressor functions of LKB1. We also found that Cyclooxygenase-2 participates in tumorigenesis in Peutz-Jeghers syndrome by promoting the growth of gastric polyps, and that inhibitor treatment suppresses the polyp formation. We also observed that these Peutz-Jeghers polyps are less differentiated than previously thought, and that signs of poor differentiation can be seen in the gastric epithelium already prior to polyp formation. In addition, we found that the polyp formation process is likely to be enhanced by other genes in addition to LKB1 and Cycloxygenase-2, as alkylating mutagenesis increased polyp formation independently of the activity of the latter. Taken together, these results point to a wide array of molecules and processes interplaying in Peutz-Jeghers tumorigenesis beyond the LKB1 kinase. Both straight molecular targets of LKB1 activity, indirect mediators of LKB1-regulated tumorigenesis, and cooperating processes have been identified. One may expect that these findings will be of use for future studies both characterizing the Peutz-Jeghers syndrome and targeting treatments for this and related tumor diseases.Peutz-Jeghers syndrom är en ärftlig sjukdom som omfattar benägenhet för att utveckla cancer, samt förekomst av pigmentfläckar på huden och ett slags godartade tumörer, polyper, i mag-tarmkanalen. Mutationer i genen LKB1 leder till Peutz-Jeghers syndrom. Denna gen innehåller koden för kinasenzymet LKB1, som påverkar andra proteiners form och funktion genom att fosforylera dem. Avhandlingsarbetet undersökte de molekylära funktionerna hos LKB1, observerade uppkomsten av tumörer vid bortfall av LKB1 och omfattade olika ingrepp i denna process, för att bättre kunna förstå Peutz-Jeghers syndrom och andra LKB1-relaterade tumörmekanismer. Främst arbetade vi med Lkb1 knockoutmusmodellen, men också till en del med Peutz-Jeghers patienter och patientvävnadsmaterial. Målsättningen var öka den molekylbaserade förståelsen för sjukdomen och att finna utvägar för att motverka den. I den första delstudien (I) undersökte vi vilka proteiner som kan fosforyleras av LKB1, och hur fosforyleringen påverkar funktionen hos dessa målproteiner. Målproteinerna visade sig alla vara kinaser i en familj med strukturell likhet med kinaset AMPK, och fosforylering via LKB1 ökade deras aktivitet. I den andra delstudien (II) undersökte vi betydelsen av proteinet COX-2för utvecklingen av polyper vid Peutz-Jeghers syndrom. COX-2 är mest känt för dess viktiga roll i inflammationsreaktioner. Vi fann att COX-2 ökar tillväxten av redan befintliga polyper, och att man kan minska på polypernas tillväxt genom att behandla med cyclooxygenas-hämmare, ämnen som vanligen används som anti-inflammatoriska värkmediciner. I studien använde vi celecoxib, en COX-2-selektiv rätt nyutvecklat preparat i denna medicingrupp. Celecoxib blev tyvärr ganska snart efter att studien (II) publicerats misstänkt för att öka på risken för hjärt- och kärlsjukdomsattacker. Även om betydelsen av denna biverkning senare tonats ner, finns det därför inte några större studier om huruvida man kunde dra nytta av cyclooxygenas-hämmare vid behandlingen av Peutz-Jeghers patienter. Våra resultat tyder på att detta vore en möjlighet. I den tredje delstudien (III) granskade vi utvecklingen av polyper vid Peutz-Jeghers syndrom, främst i musmodellen Lkb1+/-, men även hos patienter. Vi fann, att magkörtelcellerna i polyperna inte klarar av att differentiera sig tillräckligt, och att samma bristfälliga differentiering i viss mån även kan observeras i normal Lkb1+/- magslemhinna, innan andra förändringar tydande på polyputveckling kan observeras. Dessutom, i delstudie IV, undersökte vi hur mutationer i andra gener än LKB1 påverkar uppkomsten av polyper, och fann att uppkomsten av nya polyper märkbart ökar om man genererar mutationer i andra gener. Denhär effekten var separat från den COX-2-relaterade mekanismen: Antalet nya polyper ökade framom storleken på polyperna, och cyclooxygenas-hämmare hade inte längre någon märkbar effekt på polypbildningen. Tillsammans har resultaten gett ledtrådar angående sättet på vilket LKB1 motverkar tumörbildning; i delstudie I beträffande molekylnivån, och i de övriga studierna i fråga om uppkomsten och utvecklingen av polyper vid Peutz-Jeghers syndrom. Resultaten från delstudie III tyder på att slemhinneytan, epitelet, aktivt deltar i uppkomsten av polyper, medan resultaten från studierna II och IV visar på att polyperna utvecklas genom många faktorers samarbete, av vilka COX-2 är en, även om reducerad LKB1-funktion ger Peutz-Jeghers-polyperna deras karaktäristiska drag. I sin helhet bidrar resultaten till ökad förståelse för mekanismerna bakom Peutz-Jeghers syndrom, och eventuellt även till att finna helt nya, molekylbaserade behandlingar för Peutz-Jeghers-polyper och andra LKB1-relaterade tumörer

Internet-delivered cognitive behavioral therapy (iCBT) for common mental disorders and subsequent sickness absence : a systematic review and meta-analysis

Funding Information: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by the Academy of Finland (grant 315343) and the Strategic Research Council at the Academy of Finland (grants 327145 and 327148 for the DigiIn Project). LUG was partially funded by Occupational Health Helsinki. The authors also wish to acknowledge the contributions of additional data and comments by Claudia Buntrock, Martin Kraepelien, Dominique Hange, Elin Lindsäter, of authors sharing full-text versions of manuscripts as mentioned in the PRISMA Checklist, and for comments to the data analysis by Christopher Cardwell. The funders had no role in the planning, performing or reporting on this review. Publisher Copyright: © Author(s) 2022.Aim: The study aimed to critically review and synthesize the best available evidence about the effectiveness of therapist-guided internet-delivered cognitive behavioral therapy (iCBT) in terms of reducing sickness absence (SA). Methods: We searched Medline (PubMed), Embase, PsycInfo, CINAHL, and Cochrane Central (up to November 2020) for English language peer-reviewed papers that described randomized controlled trials of therapist-guided iCBT compared with usual treatment for SA in adults with common mental disorders. Eligible studies were assessed with the Cochrane Risk of Bias 1 tool, meta-analysis was conducted using a random-effects model, and standardized mean differences (SMD) with 95% confidence intervals (CI) were reported. A subgroup analysis investigated potential moderating variables (diagnosis, SA at baseline, and estimated accuracy of self-report). Results: We identified 2788 references, of which 68 remained after the completion of the systematic screening process. A hand search of reference lists yielded no additional studies. The full texts of these 68 studies were appraised critically, and 11 were deemed to be suitable for a meta-analysis. SA was similar for iCBT and usual treatment groups (SMD: 0.02, 95% CI, –0.08 to 0.11), and remained similar even after the removal of two studies in which the recall time was over 3 months (SMD: 0.00, –0.11 to 0.12). Similar SA levels in intervention and control groups at 6-month and 12-month follow-up were observed in studies of participants with depression symptoms. Conclusions: iCBT did not appear to be effective in terms of reducing (largely self-assessed) SA in adults with common mental disorders. There is a need to improve the method and consistency of assessing SA.Peer reviewe

Complexes between the LKB1 tumor suppressor, STRAD α/β and MO25 α/β are upstream kinases in the AMP-activated protein kinase cascade

BACKGROUND: The AMP-activated protein kinase (AMPK) cascade is a sensor of cellular energy charge that acts as a 'metabolic master switch' and inhibits cell proliferation. Activation requires phosphorylation of Thr172 of AMPK within the activation loop by upstream kinases (AMPKKs) that have not been identified. Recently, we identified three related protein kinases acting upstream of the yeast homolog of AMPK. Although they do not have obvious mammalian homologs, they are related to LKB1, a tumor suppressor that is mutated in the human Peutz-Jeghers cancer syndrome. We recently showed that LKB1 exists as a complex with two accessory subunits, STRADα/β and MO25α/β. RESULTS: We report the following observations. First, two AMPKK activities purified from rat liver contain LKB1, STRADα and MO25α, and can be immunoprecipitated using anti-LKB1 antibodies. Second, both endogenous and recombinant complexes of LKB1, STRADα/β and MO25α/β activate AMPK via phosphorylation of Thr172. Third, catalytically active LKB1, STRADα or STRADβ and MO25α or MO25β are required for full activity. Fourth, the AMPK-activating drugs AICA riboside and phenformin do not activate AMPK in HeLa cells (which lack LKB1), but activation can be restored by stably expressing wild-type, but not catalytically inactive, LKB1. Fifth, AICA riboside and phenformin fail to activate AMPK in immortalized fibroblasts from LKB1-knockout mouse embryos. CONCLUSIONS: These results provide the first description of a physiological substrate for the LKB1 tumor suppressor and suggest that it functions as an upstream regulator of AMPK. Our findings indicate that the tumors in Peutz-Jeghers syndrome could result from deficient activation of AMPK as a consequence of LKB1 inactivation

LKB1 is a master kinase that activates 13 kinases of the AMPK subfamily, including MARK/PAR-1

We recently demonstrated that the LKB1 tumour suppressor kinase, in complex with the pseudokinase STRAD and the scaffolding protein MO25, phosphorylates and activates AMP-activated protein kinase (AMPK). A total of 12 human kinases (NUAK1, NUAK2, BRSK1, BRSK2, QIK, QSK, SIK, MARK1, MARK2, MARK3, MARK4 and MELK) are related to AMPK. Here we demonstrate that LKB1 can phosphorylate the T-loop of all the members of this subfamily, apart from MELK, increasing their activity >50-fold. LKB1 catalytic activity and the presence of MO25 and STRAD are required for activation. Mutation of the T-loop Thr phosphorylated by LKB1 to Ala prevented activation, while mutation to glutamate produced active forms of many of the AMPK-related kinases. Activities of endogenous NUAK2, QIK, QSK, SIK, MARK1, MARK2/3 and MARK4 were markedly reduced in LKB1-deficient cells. Neither LKB1 activity nor that of AMPK-related kinases was stimulated by phenformin or AICAR, which activate AMPK. Our results show that LKB1 functions as a master upstream protein kinase, regulating AMPK-related kinases as well as AMPK. Between them, these kinases may mediate the physiological effects of LKB1, including its tumour suppressor function

Impaired Gastric Gland Differentiation in Peutz-Jeghers Syndrome

Gastrointestinal hamartomatous polyps in the Peutz-Jeghers cancer predisposition syndrome and its mouse model (Lkb1+/−) are presumed to contain all cell types native to the site of their occurrence. This study aimed to explore the pathogenesis of Peutz-Jeghers syndrome polyposis by characterizing cell types and differentiation of the epithelium of gastric polyps and predisposed mucosa. Both antral and fundic polyps were characterized by a deficit of pepsinogen C-expressing differentiated gland cells (antral gland, mucopeptic, and chief cells); in large fundic polyps, parietal cells were also absent. Gland cell loss was associated with an increase in precursor neck cells, an expansion of the proliferative zone, and an increase in smooth muscle α-actin expressing myofibroblasts in the polyp stroma. Lack of pepsinogen C-positive gland cells identified incipient polyps, and even the unaffected mucosa of young predisposed mice displayed an increase in pepsinogen C negative glands (25%; P = 0045). In addition, in small intestinal polyps, gland cell differentiation was defective, with the absence of Paneth cells. There were no signs of metaplastic differentiation in any of the tissues studied, and both the gastric and small intestinal defects were seen in Lkb1+/− mice, as well as polyps from patients with Peutz-Jeghers syndrome. These results identify impaired epithelial differentiation as the earliest pathological sign likely to contribute to tumorigenesis in individuals with inherited Lkb1 mutations