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PhD position (M/F)

This offer is available in the following languages:
Français - Anglais

Date Limite Candidature : mercredi 18 mai 2022

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General information

Reference : UMR5203-MANGAR-002
Date of publication : Wednesday, April 27, 2022
Scientific Responsible name : Julie PANNEQUIN
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

We previously demonstrated that the nuclear receptor PXR (NR1I2) is preferentially expressed and activated in colon cancer stem cells (CSC) while its knockdown (siRNA or miRNA) sensitizes CSC to chemotherapy, and thus significantly delays tumor recurrence in xenograft models. To date, there is no clinically relevant PXR inhibitor, but we have developed a first series of original compounds (PROTACs) inducing the targeted degradation of PXR.
PROTACs (“Proteolysis Targeting Chimera”) are bifunctional chemical molecules that simultaneously bind a protein of interest and an E3-ubiquitin ligase. An invention application has been filed and a first patent is being drafted. We have synthesized a first series of PXR PROTACs that induce the poly-ubiquitination of PXR which is thus degraded into small peptides and amino acids by the proteasome complex following the recruitment of the E3 ubiquitin ligase Cereblon (CRBN). This is the first chemical knock-down of this CSC chemoresistance factor.

Most specifically, we have characterized the JMV7048 molecule as the first PROTAC capable of inducing in vitro and in vivo degradation of PXR. This molecule consists on the one hand of a very high affinity ligand (1nM) for PXR and of thalidolimode, a Cereblon ligand. Tus, this PXR PROTAC approach appears as an innovative neoadjuvant strategy to induce the targeted degradation of PXR and sensitize CSCs to chemotherapies. However, we are aware that only a very small proportion of in vitro active compounds have adequate physico-chemical properties, ADME (absorption, distribution, metabolism, elimination) and toxicity allowing them to be used in clinic. It is particularly the case with such big molecules, compared to the conventional pharmacopoeia. Now, we believe that both an optimization of the JMV7048's bio-pharmaceutical properties, formulation and route of administration are needed. Thus, the optimization of the chemical structure of our 1st hit and the development of vectorization biodegradable nanoparticles based on this technology will be coupled with bio-pharmaceutical analyzes before testing them in preclinical models.

In close collaboration with the chemists from the IBMM team), the student will mainly work in the "Signalling, Plasticity and Cancer" team at the IGF. He/she will carry out most of the biological validation experiments on the different cell lines (NanoBRET CRBN, Western-blot, RT-qPCR, cell viability synergy matrices, flow cytometry, and self-renewal of CSCs), as well as in vivo. As such, an authorization for animal experimentation will be required for any application.

Work Context

The Julie PANNEQUIN's team is located at the Institute of Functional Genomics (IGF, Montpellier). This institute is a joint unit between the CNRS, INSERM and the University of Montpellier. Our research team is recognized for its work on cancer stem cells. Our research is divided into three main axes.
The first is focused on the chemoresistance of CSCs and the deciphering of the underlying mechanisms in order to identify ways to sensitize these cells to different chemotherapy agents. The second axis proposes to study the plasticity of CSCs from the angle of translational control, and particularly through RNA modifications (epitranscriptome). Finally, tumor dissemination is the subject of the third axis, with the focus on the characterization of circulating tumor cells, early dissemination and tumor dormancy.
This PhD project is at the interface between cell biology and therapeutic chemistry. It is granted by the CNRS (PRIME 80) which associates the teams of Julie PANNEQUIN (IGF) with that of Dr. Muriel AMBLARD, chemist at the Max Mousseron Institute of Biomolecules (IBMM, Montpellier). The successful candidate shall be enrolled on the CBS2 doctoral school of Montpellier.
The student will be supervised by Dr Jean Marc PASCUSSI, Research Fellow at INSERM, specialist in PXR studies.

Recent publications from our research team:
Niclosamide induces miR-148a to inhibit PXR and sensitize colon cancer stem cells to chemotherapy. Bansard L, Bouvet O, Moutin E, Le Gall G, Giammona A, Pothin E, Bacou M, Hassen-Khodja C, Bordignon B, Bourgaux JF, Prudhomme M, Hollande F, Pannequin J, Pascussi JM, Planque C. Stem Cell Reports. 2022 Apr 12;17(4):835-848.
Alteration of ribosome function upon 5-fluorouracil treatment favors cancer cell drug-tolerance. Therizols G, Bash-Imam Z, Panthu B, Machon C, Vincent A, Ripoll J, Nait-Slimane S, Chalabi-Dchar M, Gaucherot A, Garcia M, Laforêts F, Marcel V, Boubaker-Vitre J, Monet MA, Bouclier C, Vanbelle C, Souahlia G, Berthel E, Albaret MA, Mertani HC, Prudhomme M, Bertrand M, David A, Saurin JC, Bouvet P, Rivals E, Ohlmann T, Guitton J, Dalla Venezia N, Pannequin J, Catez F, Diaz JJ. Nat Commun. 2022 Jan 10;13(1):173.
CD44v6 Defines a New Population of Circulating Tumor Cells Not Expressing EpCAM. Belthier G, Homayed Z, Grillet F, Duperray C, Vendrell J, Krol I, Bravo S, Boyer JC, Villeronce O, Vitre-Boubaker J, Heaug-Wane D, Macari-Fine F, Smith J, Merlot M, Lossaint G, Mazard T, Portales F, Solassol J, Ychou M, Aceto N, Mamessier E, Bertucci F, Pascussi JM, Samalin E, Hollande F, Pannequin J. Cancers (Basel). 2021 Oct 2;13(19):4966.
FTO-mediated cytoplasmic m6Am demethylation adjusts stem-like properties in colorectal cancer cell. Relier S, Ripoll J, Guillorit H, Amalric A, Achour C, Boissière F, Vialaret J, Attina A, Debart F, Choquet A, Macari F, Marchand V, Motorin Y, Samalin E, Vasseur JJ, Pannequin J, Aguilo F, Lopez-Crapez E, Hirtz C, Rivals E, Bastide A, David A. Nat Commun. 2021 Mar 19;12(1):1716
Pregnane 1 X-receptor promotes stem cell-mediated colon cancer relapse. C. Planque*, F. Rajabi1*, ≠, J. Pannequin≠, JM. Pascussi≠. Oncotarget. 2016 Jul 18. doi: 10.18632/oncotarget.10646.

Constraints and risks

The project will require both work on human cell lines and in confined areas but will not require manipulation of radioactive products.

Additional Information

Applicants shall provide documentation that they are in possession of:
• a Master 2 degree in biochemistry, molecular or cellular biology,
• practical skills in several experimental techniques in cellular and molecular biology,
• good communication skills in French and in English,
• animal experimentation accreditation (a prerequisite ).

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