The metabolic co-regulator PGC1α suppresses prostate cancer metastasis

Cellular transformation and cancer progression is accompanied by changes in the metabolic landscape. Master co-regulators of metabolism orchestrate the modulation of multiple metabolic pathways through transcriptional programs, and hence constitute a probabilistically parsimonious mechanism for general metabolic rewiring. Here we show that the transcriptional co-activator peroxisome proliferator-activated receptor gamma co-activator 1α (PGC1α) suppresses prostate cancer progression and metastasis. A metabolic co-regulator data mining analysis unveiled that PGC1α is downregulated in prostate cancer and associated with disease progression. Using genetically engineered mouse models and xenografts, we demonstrated that PGC1α opposes prostate cancer progression and metastasis. Mechanistically, the use of integrative metabolomics and transcriptomics revealed that PGC1α activates an oestrogen-related receptor alpha (ERRα)-dependent transcriptional program to elicit a catabolic state and metastasis suppression. Importantly, a signature based on the PGC1α–ERRα pathway exhibited prognostic potential in prostate cancer, thus uncovering the relevance of monitoring and manipulating this pathway for prostate cancer stratification and treatment

Role of MAF in bone metastasis

[eng] The identification of genes that mediate metastasis is pivotal to better understand the mechanism, to develop novel drugs and to stratify patients with highest risk and consecutively administrate them preventive treatments. Despite significant advances on knowledge, diagnosis and treatment of cancer, metastasis remains the major cause of cancer-associated deaths. Bone is one of the most common organs affected by metastatic lesions for its permeability and favorable conditions for cellular growth. Constant remodeling in bone homeostasis implies an incessant degradation of the bone that release high concentrations of growth factors into the microenvironment. Thereby, growth factors benefit both, formation of new bone and/or tumor cell growth. Although the importance of bone metastatic lesions in cancer patients and the advances on the knowledge of this process, few treatments are currently administrated to patients that suffer this disease, specifically Denosumab and Zoledronic acid (ZOL). Importantly, these treatments can improve the symptoms of bone lesions but cannot cure or reverse metastasis. This fact reflects the need to detect and tackle new targetable elements to reduce bone metastatic lesions. Many molecular mechanisms have been described in bone metastasis, but only one predictor gene has been identified, MAF. MAF is a transcription factor that has been previously involved in carcinogenesis, specially in multiple myeloma (MM) and human angioimmunoblastic T-cell lymphomas (AITLs). Recently, MAF contribution has been associated for the first time with breast cancer bone metastasis. In this thesis, we determined the role of MAF in several contexts. As a first approach we demonstrated that MAF is also a predictive marker of bone metastasis in prostate cancer (PC) patients. However, regarding androgen-independent PC cell lines, an overexpression of MAF was not enough to drive colonization of the mouse bone. Secondly, we report the beneficial effect of MAF downregulation on preventing skeletal metastasis in BoM2, a highly bone metastatic MCF7-derived cell line. MAF impinged bone colonization in a higher degree that other treatments against bone metastasis, such as PTHrP antagonist or recombinant OPG. This fact identifies MAF as a new potential target to focus on the generation of new drugs. Finally, MAF showed a tendency to redirect metastases to other organs than bone in the presence of ZOL treatment in vivo. Thus, we validated the association between MAF overexpression and an increase on extraskeletal metastases after ZOL preventive treatment in non-postmenopausal BC patients. Moreover, a mouse model was generated to better understand the biology of MAF- derived bone metastasis within complete stromal interactions. We designed a transgenic mouse model to express MAF in the mammary gland in an inducible manner. To this end, we generated two constructs; the first contains rtTA, renilla and katushka under MMTV promoter, and the second contains MAF, luciferase and tGFP under Tet-On promoter. We demonstrated the incorporation of several copy numbers of both transgenes in two independent colonies and we detected transgene expression under doxycycline activation by means of luminescent signal. Even though both colonies incorporated several copy number of the transgene, their expression was soft and some relevant leakiness was observed in the non-treated MAF mice. No differences were observed in terms of mammary gland development between transgene-expressing MAF mice and wild-type mice, as well as no tumor initiation was detected in any group. Notably, MAF Tg mouse was crossed with MMTV-PyMT to generate double Tg mice (PyMT-MAF). PyMT-MAF tumor growth presented no significant differences compared to PyMT in terms of time to tumor formation and growth rate. Importantly, no bone metastases were observed at 3-month-old mice of any group. Thus, the generation of this animal model provided new insights to generate a novel bone metastatic mouse model.[spa] La identificació de gens implicats en el procés de la metàstasis és bàsica per tal d’entendre el mecanisme d’aquest procés, per reconèixer els pacients amb més risc de patir-lo i tractar-los selectivament i finalment pel desenvolupament de nous fàrmacs. Recentment, s’ha identificat el gen MAF com a predictor d’un alt risc de patir metàstasis òssia en pacients de càncer de mama. En aquesta tesi hem determinat el paper de MAF en diferents contexts. Per una banda, hem demostrat que MAF és un marcador predictiu de les metàstasis òssies també en pacients amb càncer de pròstata. Tot i així, una sobreexpressió de MAF en cèl·lules de càncer de pròstata andrògen-independents no va ser suficient per conduir la colonització a l’òs. Per altra banda, hem demostrat que reduir els nivells de MAF en les cèl·lules BoM2, derivades de les cèl·lules de càncer de mama MCF7, redueix la tendència d’aquestes cèl·lules a metastatitzar a l’òs. Cal destacar que aquest efecte és superior al d’altres tractaments com poden ser OPG recombinant o el pèptid antagonista de PTHrP, indicant MAF com a element potencial per a la generació de nous fàrmacs. Finalment, MAF afecta el patró de metàstasis de les cèl·lules ER- de càncer de mama després del tractament preventiu amb àcid Zoledronic, tal com s’observa en pacients. Per abordar el paper de MAF en el càncer de mama tenint en compte les interaccions amb l’estroma i el sistema immunitari, es va dissenyar un model animal transgènic que sobreexpressava MAF en la glàndula mamària de forma induïble. Es va demostrar la incorporació de vàries còpies del transgen en el ADN genòmic i també es va detectar, per senyal bioluminiscent, la inducció per doxiciclina de l’expressió del transgen. Cal destacar que l’expressió era feble i en molts casos inespecífica i independent al tractament amb doxiciclina. El desenvolupament mamari en aquest model no demostrava cap alteració com tampoc es va detectar cap indici de formació de tumor. Aquest model es va creuar amb MMTV-PyMT, i els tumors de les femelles doble transgèniques (PyMT-MAF) no van presentar cap diferència en el temps necessari per a la formació de tumors ni en la velocitat de creixement comparat amb PyMT. De manera destacable, no es van observar metàstasis òssies en el moment del sacrifici. D’aquesta manera, la generació del ratolí MAF transgènic ens va donar noves perspectives per enfocar la generació d’un nou model animal que generi metàstasis òssies

Can we predict and prevent specific sites of metastases in breast cancer patients?

Despite improvements in breast cancer therapies, cancer cells frequently spread to distant organs years or decades after primary tumor surgery and adjuvant treatment. This expansion, known as metastasis, can bring about fatal consequences. Traditionally, the risk of metastasis has been predicted by prognostic factors such as tumor size, axillary lymph node status and histological grade. More recently, genomic tests have also been used for this purpose. The presence of ER, PR and ERBB2 gene amplification are currently key markers in the characterization of breast tumor type that drive the selection of specific therapies. ER-positive tumors are more prone to metastasize into the bone, whereas ER-negative tumors preferentially spread to visceral organs such as lung, liver and brain. However, the reliability of these markers is limited. In this regard, substantial efforts have been made to find new markers that predict the most probable target organ of metastasis, with the aim to improve diagnosis and develop organ-specific treatments for breast cancer metastatic patients

Quantitative assessment of anti-gravity reflexes to evaluate vestibular dysfunction in rats

The tail-lift reflex and the air-righting reflex are anti-gravity reflexes in rats that depend on vestibular function. To obtain objective and quantitative measures of performance, we recorded these reflexes with slow-motion video in two experiments. In the first experiment, vestibular dysfunction was elicited by acute exposure to 0 (control), 400, 600, or 1000 mg/kg of 3,3′-iminodipropionitrile (IDPN), which causes dose-dependent hair cell degeneration. In the second, rats were exposed to sub-chronic IDPN in the drinking water for 0 (control), 4, or 8 weeks; this causes reversible or irreversible loss of vestibular function depending on exposure time. In the tail-lift test, we obtained the minimum angle defined during the lift and descent maneuver by the nose, the back of the neck, and the base of the tail. In the air-righting test, we obtained the time to right the head. We also obtained vestibular dysfunction ratings (VDRs) using a previously validated behavioral test battery. Each measure, VDR, tail-lift angle, and air-righting time demonstrated dose-dependent loss of vestibular function after acute IDPN and time-dependent loss of vestibular function after sub-chronic IDPN. All measures showed high correlations between each other, and maximal correlation coefficients were found between VDRs and tail-lift angles. In scanning electron microscopy evaluation of the vestibular sensory epithelia, the utricle and the saccule showed diverse pathological outcomes, suggesting that they have a different role in these reflexes. We conclude that these anti-gravity reflexes provide useful objective and quantitative measures of vestibular function in rats that are open to further development