MAPK11 (p38ß) is a major determinant of cellular radiosensitivity by controlling ionizing radiation-associated senescence: An in vitro study.

Background and purpose: MAPKs are among the most relevant signalling pathways involved in coordinating cell responses to different stimuli. This group includes p38MAPKs, constituted by 4 different proteins with a high sequence homology: MAPK14 (p38α), MAPK11 (p38ß), MAPK12 (p38γ) and MAPK13 (p38δ). Despite their high similarity, each member shows unique expression patterns and even exclusive functions. Thus, analysing protein-specific functions of MAPK members is necessary to unequivocally uncover the roles of this signalling pathway. Here, we investigate the possible role of MAPK11 in the cell response to ionizing radiation (IR). Materials and methods: We developed MAPK11/14 knockdown through shRNA and CRISPR interference gene perturbation approaches and analysed the downstream effects on cell responses to ionizing radiation in A549, HCT-116 and MCF-7 cancer cell lines. Specifically, we assessed IR toxicity by clonogenic assays; DNA damage response activity by immunocytochemistry; apoptosis and cell cycle by flow cytometry (Annexin V and propidium iodide, respectively); DNA repair by comet assay; and senescence induction by both X-Gal staining and gene expression of senescence-associated genes by RT-qPCR. Results: Our findings demonstrate a critical role of MAPK11 in the cellular response to IR by controlling the associated senescent phenotype, and without observable effects on DNA damage response, apoptosis, cell cycle or DNA damage repair. Conclusion: Our results highlight MAPK11 as a novel mediator of the cellular response to ionizing radiation through the control exerted onto IR-associated senescence.

An association between viral genes and human oncogenic alterations: the adenovirus E1A induces the Ewing tumor fusion transcript EWS-FLI1.

Malignant transformation of human cells requires the accumulation of multiple genetic alterations, such as the activation of oncogenes and loss of function of tumor suppressor genes or those related to genomic instability. Among the genetic alterations most frequently found in human tumors are chromosomal translocations that may result in the expression of chimeric products with transforming capability or are able to change the expression of oncogenes. We show here that the adenovirus early region 1A (E1A) gene can induce a specific human fusion transcript (EWS-FLI1) that is characteristic of Ewing tumors. This fusion transcript was detected by RT-PCR in normal human fibroblasts and keratinocytes after expression of the adenovirus E1A gene, as well as in human cell lines immortalized by adenoviruses. Cloning and sequencing of the RT-PCR product showed fusion points between EWS and FLI1 cDNA identical to those detected in Ewing tumors. In addition, we detected a chimeric protein by western blot analysis and immunoprecipitation and a t(11,22) by fluorescent in situ hybridization. This association between a single viral gene and a specific human fusion transcript indicates a direct link between viral genes and chromosome translocations, one of the hallmarks of many human tumors.

p38ß (MAPK11) mediates gemcitabine-associated radiosensitivity in sarcoma experimental models.

BACKGROUND AND PURPOSE: Gemcitabine is an antitumour agent currently used in the treatment of several types of cancer with known properties as a radiosensitizer. p38MAPK signalling pathway has been shown to be a major determinant in the cellular response to gemcitabine in different experimental models. However, the molecular mechanism implicated in gemcitabine-associated radiosensitivity remains unknown. MATERIALS AND METHODS: The human sarcoma cell lines A673 and HT1080, and a mouse cell line derived from a 3-methylcholanthrene induced sarcoma were used as experimental models. Modulation of p38MAPKs was performed by pharmacological approaches (SB203580) and genetic interference using lentiviral vectors coding for specific shRNAs. Viability was assessed by MTT. Gene expression was evaluated by western blot and RT-qPCR. Induction of apoptosis was monitored by caspase 3/7 activity. Response to ionizing radiation was evaluated by clonogenic assays. RESULTS: Our data demonstrate that chemical inhibition of p38MAPK signalling pathway blocks gemcitabine radiosensitizing potential. Genetic interference of MAPK14 (p38α), the most abundantly expressed and best characterized p38MAPK, despite promoting resistance to gemcitabine, it does not affect its radiosensitizing potential. Interestingly, specific knockdown of MAPK11 (p38ß) induces a total loss of the radiosensitivity associated to gemcitabine, as well as a marked increase in the resistance to the drug. CONCLUSION: The present work identifies p38ß as a major determinant of the radiosensitizing potential of gemcitabine without implication of p38α, suggesting that p38ß status should be analysed in those cases in which gemcitabine is combined with ionizing radiation.

P53 pathway is a major determinant in the radiosensitizing effect of Palbociclib: Implication in cancer therapy.

Targeting cell cycle has become one of the major challenges in cancer therapy, being Palbociclib, a CDK4/6 inhibitor, an excellent example. Recently, it has been reported that Palbociclib could be a novel radiosensitizer agent. In an attempt to clarify the molecular basis of this effect we have used cell lines from colorectal (HT29, HCT116) lung (A549, H1299) and breast cancer (MCF-7). Our results indicate that the presence of a p53 wild type is strictly required for Palbociclib to exert its radiosensitizing effect, independently of the inhibitory effect exerted on CDK4/6. In fact, abrogation of p53 in cells with functional p53 blocks the radiosensitizing effect of Palbociclib. Moreover, no radiosensitizing effect is observed in cells with non-functional p53, but restoration of p53 function promotes radiosensitivity associated to Palbociclib. Furthermore, the presence of Palbociclib blocks the transcriptional activity of p53 in an ATM-dependent-fashion after ionizing radiation exposure, as the blockage of p21/WAF1 expression demonstrates. These observations are a proof of concept for a more selective therapy, based on the combination of CDK4/6 inhibition and radiotherapy, which would only benefit to those patients with a functional p53 pathway.

Blockage of autophagic flux is associated with lymphocytosis and higher percentage of tumoral cells in chronic lymphocytic leukemia of B cells.

PURPOSE: Autophagy has lately emerged as an important biological process with implications in several hematological pathologies. Recently, a growing body of evidence supports a putative role of autophagy in chronic lymphocytic leukemia; however, no definitive clue has been established so far. To elucidate this issue, we have developed a pilot study to measure autophagic flux in peripheral blood mononuclear cells from chronic lymphocytic leukemia patients, and explored its correlation with classical clinical/analytical parameters. METHODS/PATIENTS: Thirty-three chronic lymphocytic leukemia patients participated in the study. Autophagic flux in peripheral blood mononuclear cells was determined by western blot measuring the levels of the proteins p62 and lipidated LC3. Moreover, p62 mRNA levels were analyzed by RT-qPCR. RESULTS: Lymphocytosis and the percentage of tumoral lymphocytes in chronic lymphocytic leukemia patients statistically correlate with a blocked autophagic flux. CONCLUSION: Alterations in autophagic flux could play an important role in the physiopathology of chronic lymphocytic leukemia.

Adenovirus E1A orchestrates the urokinase-plasminogen activator system and upregulates PAI-2 expression, supporting a tumor suppressor effect.

Invasiveness and metastatic potential are the two most important properties defining malignancy. The adeno-virus E1A (Ad-E1A) gene has a dual effect as a proliferative gene and as a tumor-suppressor gene, decreasing tumor growth and the metastatic potential of malignant cells. In order to study genes related with the antimetastatic effect of Ad-E1A in human cells, we performed a microarray analysis using OncoChiptrade mark. In three independent experiments, NIH3T3, IMR90 and MDA MB 435 cells were infected with pLPC retroviruses carrying the adenovirus 12S E1A gene or the GFP gene. We analyzed cDNA expression by using the CNIO OncoChipTM, a cDNA microarray containing a total of 6386 genes represented by 7237 clones. uPA, uPAr, tPA, PAI-1 and PAI-2 were also studied at RNA and protein levels. Microarrays of cDNA expression, RT-PCR and Western blot performed in IMR90 E1A-expressing cells showed downregulation of uPA, uPAr, tPA, PAI-1 and upregulation of PAI-2. These results were confirmed in NIH3T3 and MDA MB 435 breast carcinoma cells, with PAI-2 upregulation by RT-PCR and Western blot. In addition, zymographic analysis demonstrated that E1A expression greatly reduced the gelatinase activity of the pro-MMP2 and -MMP9 proteins. We propose that adenovirus E1A may orchestrate the expression of most members of the urokinase-plasminogen activation system, downregulating potentially invasive genes and upregulating PAI-2, which is associated with a better prognosis in human tumors.

A role for the p38 mitogen-acitvated protein kinase pathway in the transcriptional activation of p53 on genotoxic stress by chemotherapeutic agents.

The tumor suppressor p53 plays a central role in sensing damaged DNA and orchestrating the consequent cellular responses. However, how DNA damage leads to the activation of p53 is still poorly understood. In this study, we have found that the p38 mitogen-activated protein kinase (MAPK) plays a key role in the activation of p53 by genotoxic stress when provoked by chemotherapeutic agents. Indeed, we found that blockade of p38 prevents stimulation of the transcriptional activity of p53 and that activation of the p38 pathway is sufficient to stimulate p53 function. Furthermore, we observed that p38 does not affect the accumulation of p53 in response to DNA damage or its nuclear localization. In contrast, we observed that p38 associates physically with p53, and we provide evidence that this MAPK phosphorylates the NH2-terminal transactivation domain of p53 in serine 33, thereby stimulating its functional activity. Moreover, inhibition of the p38 MAPK diminished the apoptotic fraction of cells exposed to chemotherapeutic agents and increased cell survival, thus suggesting a role for p38 activation in the apoptotic response to genotoxic stress when elicited by drugs used in cancer therapy.

CHK1 expression in Gastric Cancer is modulated by p53 and RB1/E2F1: implications in chemo/radiotherapy response.

Radiation has a limited but relevant role in the adjuvant therapy of gastric cancer (GC) patients. Since Chk1 plays a critical function in cellular response to genotoxic agents, we aimed to analyze the role of Chk1 in GC as a biomarker for radiotherapy resistance. We analyzed Chk1 expression in AGS and MKN45 human GC cell lines by RT-QPCR and WB and in a small cohort of human patient's samples. We demonstrated that Chk1 overexpression specifically increases resistance to radiation in GC cells. Accordingly, abrogation of Chk1 activity with UCN-01 and its expression with shChk1 increased sensitivity to bleomycin and radiation. Furthermore, when we assessed Chk1 expression in human samples, we found a correlation between nuclear Chk1 accumulation and a decrease in progression free survival. Moreover, using a luciferase assay we found that Chk1's expression is controlled by p53 and RB/E2F1 at the transcriptional level. Additionally, we present preliminary data suggesting a posttranscriptional regulation mechanism, involving miR-195 and miR-503, which are inversely correlated with expression of Chk1 in radioresistant cells. In conclusion, Chk1/microRNA axis is involved in resistance to radiation in GC, and suggests Chk1 as a potential tool for optimal stratification of patients susceptible to receive adjuvant radiotherapy after surgery.

Lack of correlation between p53 protein level and sensitivity of DNA-damaging agents in keratinocytes carrying adenovirus E1a mutants.

p53 tumor suppressor protein is required for efficient execution of apoptosis after DNA-damage in many cell systems. Since the oncogene E1a confers susceptibility to DNA-damaging agents and stabilizes p53 protein, we investigate whether the sensitivity to anticancer drugs of E1a-expressing cells was mediated by binding to a specific set of cellular proteins (p60, p105, p107 and p300) and related to the induction of apoptosis and the level of p53 protein. We studied the effect of cisplatin (CDDP), doxorubicin (DOX) and ionizing radiation (RX) on murine keratinocytes (PAM 212) transfected by the wild type E1a oncogene or several E1a mutants which bind to different subsets of cellular proteins. Keratinocytes transfected with the mutant d1787N (which binds to p60, p105, p107 and p300) showed a lethality in response to CDDP (10 micrograms ml-1) fourfold higher than controls and threefold higher in response to DOX and radiation (5 grays). The sensitivity of keratinocytes carrying the mutant NTd1598 (binding to p105, p107 and p60) to DNA-damaging agents was similar to that of control keratinocytes, while mutant d1922/947 (binding only to p300) were resistant to CDDP and RX but sensitive to DOX. Apoptosis (after 24 h) studied by DNA fragmentation and flow cytometry was only observed in cells carrying the wild type E1a or the mutant d1787N. After treatment with DNA-damaging agents, p53 protein expression increased in all the cell lines and no rE1ation to sensitivity to anticancer agents or induction of apoptosis was observed. From these results, we conclude that cell sensitivity to cisplatin and ionizing radiation induced by the E1a oncogene requires binding to p105, p107 and p300 cellular proteins, while sensitivity to Doxorubicin requires binding only to p300. Interestingly, p53 protein levels were related to the binding to the p300 protein. The high levels of p53 after CDDP and DOX in the mutant d1922/947, which are only sensitive to DOX, suggest that E1a oncogene products may induce sensitivity to DNA-damaging agents by p53-related and unrelated pathways.

Carcinoma cell lines become sensitive to DNA-damaging agents by the expression of the adenovirus E1A gene.

Squamous cell carcinomas can show different oncogenic alterations, histological patterns, and an unpredictable clinical behavior. We previously reported that the adenovirus E1a gene may induce sensitivity to DNA-damaging agents in mouse keratinocytes. In order to study whether E1a expression could be used as a therapeutic agent in different malignant cell lines carrying mutations on the p53 gene and other oncogenic alterations, we transfected and infected several murine and human carcinoma cell lines (HaCa4; MSC11A5; HeLa) with vectors containing the 13S or 12S E1a region. We evaluated the sensitivity to cisplatin (CDDP), doxorubicin (DOX) and gamma irradiation (RX) by the crystal violet method. The induction of apoptosis was assessed by flow cytometry and presence of DNA ladders in agarose gels. The expression of E1a and the tumor suppressor p53 protein was analysed by Western blotting. The carcinoma cell lines expressing E1a were about four- to tenfold more sensitive to CDDP and RX, respectively, than the control cells. Moreover, the reduction in cell viability and cell growth after exposure to CDDP or RX was very significant in the carcinoma cells expressing E1a. With these results, we conclude that expression of E1a may confer great sensitivity to DNA-damaging agents on squamous cell carcinoma cells independently of the p53 protein status and other oncogenic alterations.

In vivo antitumor effect of retrovirus-mediated gene transfer of the adenovirus E1a gene.

The adenovirus E1a gene has been shown to be associated with high sensitivity to DNA-damaging agents and a decrease in the tumorigenicity of some human malignant cell lines. We have analyzed the tumorigenicity of the murine epidermoid carcinoma cell lines MSC11A5 and HaCa4, which have constitutive E1a expression, after the concomitant injection of retrovirus E1a producer cells with the carcinoma cells and even after the intratumoral injection of the E1a producer cells. The level of E1a expression was studied by Western blotting. Tumors induced by carcinoma cell lines expressing E1a showed greater latencies and less tumorigenicity. In the spindle cell carcinomas MSC11A5, E1a gene expression partially blocked tumorigenicity. Similar results were obtained after the concomitant injection of the carcinoma cells and the retrovirus E1a producer cells. Intratumoral injection of retrovirus E1a producer cells was associated with a significant delay of tumorigenicity. By transfection with different E1a mutants Ntd1598, d1922/947, and d1787N, we observed that only the mutant that has complete CR2 domains is associated with the decrease in tumorigenicity. According to these results, we conclude that, at least in these carcinoma cell lines, E1a expression exerts a significant antitumor effect in vivo that is mediated by the CR2 region of E1a gene. We propose that injection of retrovirus E1a producer cells may be a novel therapeutic approach in cancer.

Adenovirus lacking the 19-kDa and 55-kDa E1B genes exerts a marked cytotoxic effect in human malignant cells.

UNLABELLED: The adenovirus (Ad) E1A gene exerts an antitumor effect and can induce sensitivity to treatment with DNA-damaging agents. In contrast, the Ad 19-kDa E1B protein inhibits E1A-mediated apoptosis and the 55-kDa E1B inactivates the p53 protein. In this paper, we study the in vitro and in vivo effects of a 19-kDa and 55-kDa E1B-defective Ad in several malignant human tumor cell lines. MATERIALS AND METHODS: Nontumorigenic human fibroblasts (CCD-45SK and Hs67), peripheral blood lymphocytes, and several human tumor cell lines derived from cervix, colon, and breast carcinomas, epidermoid carcinoma, and osteosarcoma (HeLa, HT29, MCF7, Saos-2, and A431 cell lines) were studied. Wild-type (wt) Ad type 5 and H5 dL118 Ad, a mutant with the deleted E1B region, were employed. The cells were infected at 20 plaque-forming units, and cell viability was evaluated by the crystal violet method. In the in vivo experiments, 2 x 10(6) cells from the carcinoma cell lines HeLa, A431 and HT29 were injected into nude mice. The tumorigenicity of previously infected cells and after an intratumoral injection of Ad was analyzed. The mice received whole-body gamma-irradiation. RESULTS: The H5 dL118 mutant produced a marked cytopathic effect in all of the malignant cells, surpassing that of the wt Ad; viability at 72 hours ranged from 11% to 20% for H5 dL118 Ad and from 70% to 93% for the wt Ad with respect to uninfected controls. In the in vivo experiments, a total inhibition of tumorigenicity was detected when cells were infected prior to injection and a partial and transitory decrease in tumorigenicity was detected when the mutant H5 dL118 was injected intratumorally. gamma-irradiation enhanced the in vivo antitumor effects. CONCLUSIONS: These results indicate that infection with completely E1B-deficient Ads induced a marked cytopathic effect on malignant cells that was higher than that seen for wt Ads; in addition, infection with such Ads exerts a tumor suppressor effect in vivo.

Selective effects of E1B-defective adenoviruses and adenovirus E1A mutants in deficient mouse primary embryonic fibroblasts.

E1B-defective adenoviruses have been described as exerting selective cytopathic effects on transformed cells. Previously, we showed that adenovirus dl118, lacking both E1B proteins, very efficiently kills most human malignant cell lines. In order to study whether these selective effects were due to selective replication of dl118 in cells harboring specific genetic alterations, we compared the viability of various deficient mouse primary fibroblasts. We studied mouse embryonic fibroblasts (MEFs) derived from p16, p21, p27 and p53 knockout mice, as well as wild-type MEFs. We infected them with 100 p.f.u. of adenoviruses adl118, adwt300, and adenoviruses carrying the E1A mutant 922 (the E1a product only binds to the p300 and related proteins) and Ad646 (the E1A product binds to the pRb and related proteins). The percentage of infectivity was evaluated with an adenovirus carrying the green fluorescent protein (AdGFP). With AdGFP, clear green fluorescent signals were detected in more than 70% of the cells after 3 days of infection. After infection with several adenoviruses, we observed that E1A mutant 922 killed all the MEFs. Conversely, the E1a mutant Ad646 exerted its major effects on control wild-type MEFs. Moreover, Adl118 killed the wtMEFs and other MEFs slightly more efficiently than did wtAd, but less than Ad922. No viral replication was detected by adding the obtained supernatants to HEK293 cells. Due to the absence of significant viral replication on these cells, the results could be interpreted as direct effects of E1A and E1A mutant proteins on the different mouse cells carrying diverse genetic alterations.

In vivo radiosensitizing effect of the adenovirus E1A gene in murine and human malignant tumors.

The adenovirus E1A gene is a potent inducer of chemosensitivity and radiosensitivity through p53-dependent and independent mechanisms. We have studied the sensitivity of murine (MSC11A5, a sarcomatoid epidermoid carcinoma) and human (HeLa, human cervix carcinoma) E1A-expressing tumors, in vivo, after treatment with cisplatin or gamma-irradiation. In athymic mice, half-body irradiation was performed in an AECL Cobalt unit, at an SSD of 80 cm. Daily fractions of 300 cGy over 3 days, up to a total dose of 9 Gy. Cisplatin was injected intraperitoneally at a dose of 9 mg per kg of body weight. After gamma-irradiation or intraperitoneal injection of cisplatin, about 30% of the E1A-expressing tumors regressed completely or were associated with a marked decrease in tumorigenicity over the following weeks. We conclude that malignant tumors, when expressing adenovirus E1A, are very sensitive to treatment with DNA-damaging agents, in vivo, regardless of the p53 status of the tumors.

A genetic model for undifferentiated cell tumor formation: similar tumors formed by different cell lines transformed by the E1A oncogene.

The activation of oncogenes and the mutation/deletion of suppressor genes may be involved in tumor heterogeneity. In an attempt to study tumor heterogeneity, we transformed cell lines from epithelial (PAM 212), mesenchymal (NIH-3T3), or melanocytic origin (L-BIOBR) with the wild type E1a oncogene. To make the cell lines tumorigenic, cells were infected with Harvey sarcoma virus carrying the v-H-ras oncogene. The transformed cells were injected into nude mice and the tumors studied by optical and electron microscopy. The tumors formed by v-H-ras-transformed cells consisted of epitheliod melanomas, spindle cells sarcomas and poorly-differentiated carcinomas, depending on the cell of origin. In contrast, the tumors obtained from cells also carrying the E1a oncogene showed a predominant small and undifferentiated cell pattern regardless of the cell of origin. We conclude that the E1a oncogene products induce a negative control of differentiation, independent of the cell type, and that tumors formed by cells carrying the E1a oncogene display an undifferentiated cell pattern.

Tumor heterogeneity: morphological, molecular and clinical implications.

Malignant tumors are characterized by their great heterogeneity and variability. There are hundreds of different types of malignant tumors that harbour many oncogenic alterations. The tumor heterogeneity has important morphological, molecular and clinical implications. Except for some hematopoietic and lymphoproliferative processes and small cell infant tumors, there are not specific molecular alterations for most human tumors. In this review we summarize the most important aspects of carcinogenesis and chemoradiosensitivity of malignant cells. In this regard, some oncogenes such as neu, ras and bcl-2 have been associated with cellular resistance to treatment with anticancer agents. The knowledge of oncogenic alterations involved in each tumor can be important to correlate the morphological features, the genetic background, the prognosis and the clinical response to treatment with anticancer agents. Based on the molecular background of the tumor there are new cancer gene therapy protocols. For example using adenovirus Ela in tumors with overexpression of neu oncogene, inhibitors of tyrosine kinase specific for the PDGF receptor in glioma, inhibitors of farnesil transferase to prevent ras activity in tumors with mutations in the ras gene.

Perspectives in gene therapy.

Gene therapy is understood to be both the restitution of genetic alterations caused by mutation or deletion and the control of overexpressed genes. The concept of gene therapy can also encompass molecular strategies to induce cell death in tumor cell by either the so-called "suicided genes" or by certain viral genes that induce a more selective cell death among the transformed cells. The prospect for the clinical application of gene therapy are enormous and, at least theoretically, its utilization can be extended to a number of diseases known to have a genetic basis, and to neoplastic processes. This review summarizes some of the projects that are currently underway involving neoplastic diseases, liver diseases, hematopoietic cells and respiratory tract cells. The results of most of the ongoing protocols are not yet conclusive, and presumibly, their clinical application is still some years away. One of the major limitations is the method of introducing the genetic sequences into the cells and achieving their constitutive expression by the cells. For ethical reasons, this approach should not be done in germ cells, but at the level of the tissue or cells most closely involved in the development of each gene-based disease. The methods employed in gene therapy are discussed, focusing on those mediated by the application of viral vectors, as well as those requiring the use of liposomes and others.

[Role of mitogen-activated protein kinase (MAPK) in the sporadic renal cell carcinoma]. / Papel de las proteínas quinasas activadas por mitógenos (MAPK) en el carcinoma de células renales esporádico.

CONTEXT: Only on the basis of the involvement of the vhl suppressor gene in the cases of renal cell carcinomas (RCC), the involvement of the signaling pathway between the pVHL and the Hypoxia inducible factor 1, alpha (HIF-1α) has been evaluated because of the need to find new diagnostic and prognostic and response to drugs markers. EVIDENCE SYNTHESIS: The overexpression of HIF-1α confers better prognosis in clear cell type RCC (ccRCC). Furthermore, HIF-1α regulates other genes, specifically that of the carbon anhydrase IX (CA-IX), whose overexpression is practically only of the ccRCC and its determination is useful for this subtype. However, the involvement of the CA-IX has not been demonstrated in the prognosis or in the response to immunomodulators or antiangiogenics. Therefore, it is necessary to make a global evaluation of all this pathway: pVHL → HIF-1α → CA-IX, and even the analysis of other proteins and signaling pathways that also control the HIF-1α activity. In the latter case, the MAPK are critical in the HIF-1α activation, there being evidence on the experimental level of the control on its activity. although its clinical role as a biomarkers has not been established. Although the role of the MAPK in the phenomena of resistance to conventional chemotherapy and radiotherapy has been demonstrated, it has not been demonstrated in response to sorafenib, an important piece of information if we consider that it is an inhibitor of several protein kinases. Recently, it has been observed that the MAPK may be involved in the responses to different therapies, included those based on tyrosine kinase inhibitors. CONCLUSIONS: The confirmation of these data would suppose an explanation of the variation observed between patients who, with the same functional alteration of the vhl gene, have a different biological, clinical behavior and better selection of non-surgical therapies.