The stability of c-Myc is regulated by multiple Ras effector pathways. Phosphorylation at Ser 62 stabilizes c-Myc, whereas subsequent phosphorylation at Thr 58 is required for its degradation. Here we show that Ser 62 is dephosphorylated by protein phosphatase 2A (PP2A) before ubiquitination of c-Myc, and that PP2A activity is regulated by the Pin1 prolyl isomerase. Furthermore, the absence of Pin1 or inhibition of PP2A stabilizes c-Myc. A stable c-Myc(T58A) mutant that cannot bind Pin1 or be dephosphorylated by PP2A replaces SV40 small T antigen in human cell transformation and tumorigenesis assays. Therefore, small T antigen, which inactivates PP2A, exerts its oncogenic potential by preventing dephosphorylation of c-Myc, resulting in c-Myc stabilization. Thus, Ras-dependent signalling cascades ensure transient and self-limiting accumulation of c-Myc, disruption of which contributes to human cell oncogenesis.

In order to reduce mutilation, nipple-areola complex (NAC) conservation can be proposed for the treatment of breast cancer when mastectomy is indicated. To reduce the risk of retro areolar recurrence, a novel radiosurgical treatment combining subcutaneous mastectomy with intraoperative radiotherapy (ELIOT) is proposed. One thousand and one nipple sparing mastectomies (NSM) were performed from March 2002 to November 2007 at the European institute of oncology (EIO), for invasive carcinoma in 82% of the patients and in situ carcinoma in 18%.Clinical complications, aesthetic results, oncological and psychological results were recorded. A comparison was performed between the 800 patients who received ELIOT and the 201 who underwent delayed one-shot radiotherapy on the days following the operation. The median follow up time was 20 months (range 1-69) for a follow up performed in 83% of the patients. The NAC necrosed totally in 35 cases (3.5%) and partially in 55 (5.5%) and was removed in 50 (5%). Twenty infections (2%) were observed and 43 (4.3%) prostheses removed. The median rate of the patients for global cosmetic result on a scale ranging from 0 (worst) to 10 (excellent) was 8. Evaluation by the surgeon in charge of the follow-up gave a similar result. Only 15% of the patients reported a partial sensitivity of the NAC. Of the fourteen (1.4%) local recurrences, ten occurred close to the tumour site, all far from the NAC corresponding to the field of radiation. No recurrences were observed in the NAC. In a group of patients characterized by a very close free margin under the areola, no local recurrence was observed. Overall, 36 cases of metastases and 4 deaths were observed. No significant outcome difference was observed between the 800 patients receiving intraoperative radiotherapy (ELIOT) and the 201 patients receiving delayed irradiation.

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International audienceWhen the conservative treatment is not recommended, Nipple Sparing Mastectomy (NSM) is proposed more and more frequently for the surgical treatment of breast cancer. The risk of local recurrence behind the nipple areolar complex (NAC) is the main limiting factor of the NSM procedure. To minimize such risk, we proposed in 2002 a intraoperative radiotherapy of the preserved NAC. From March 2002 to November 2006, 579 cases (in 570 patients) of NSM were performed for carcinoma. The median follow up time was 19 months (Range: 1–60). The subcutaneous mastectomy was performed through an incision removing a portion of the skin overlying the tumour. An extemporaneous histological examination was performed on the retroareolar glandular tissue. If the histology was positive the patient was not considered eligible. Then an intraoperative radiotherapy with electrons (ELIOT) of 16 Gy in one shot was delivered on the NAC area. An immediate breast reconstruction was done using implants in most cases and in several cases a musculocutaneous flaps, usually in large breast. The number of local recurrences was recorded and the correlation between their occurrence and the clinical and histological criteria were analysed using the Gray test statistical method in a competing framework. In 516 cases the negative retroareolar frozen section biopsy was confirmed by the final histology, while in 63 cases, the final histology showed foci of carcinoma. Seven out of these 63 cases underwent a secondary NAC removal. In the 56 cases which preserved areolas we did not observe any local recurrence after 19 months follow up. The probability of retro areola positive histology increases with the tumour size. and was not related to the nodal status. The rate of local relapses was 0.9% per year. We didn't find any significant difference in the local relapse rate according to different patient's and tumour's features. Most relapses were located close to the tumour bed but never in the NAC area. Our study confirms that the local recurrence rate in the NSM completed with local radiotherapy on the NAC is not higher than the usual rate observed in the literature and the preservation of the NAC does not increase the risk. The absence of local recurrence in the region where a portion of glandular tissue has been purposely preserved is a good argument in favour of ELIOT