Hye Jung Baek, Geun Hee Han, Eun Joo Cho, Jihao Xu, Min Kyung Ki, Eun Jung Park, Tae Hyun Kim, Dong Hoon Shin, Heesun Cheong, Chu-Xia Deng, Sung Chul Lim, Chang-il Hwang, Daehee Hwang, Sang Soo Kim
<p>Inherited mutation in breast cancer susceptibility gene 1 (<i>BRCA1</i>) is strongly associated with mammary tumors that exhibit triple-negative characteristics, are insensitive to endocrine-targeted therapies, and show basal-like properties, including aggressive phenotypes [<span>1, 2</span>]. It has been reported that the average cumulative risk of breast cancer for <i>BRCA1</i> mutation carriers by age 70 years is 57% (95% confidence interval [CI]: 47%-66%) [<span>3</span>]. Despite the high incidence and aggressive characteristics of <i>BRCA1</i>-associated breast cancer, few substantial improvements in preventing or treating this cancer have been made, largely due to the challenges of clinic-based cohort studies. During malignant transformation, cancer progression is facilitated by metabolic reprogramming–one of the hallmark characteristics of cancer. Previously, we found that inhibition of AKT is a potential strategy for the prevention and therapeutic management of <i>Brca1</i>-mutant mammary tumors. However, pharmacological inhibition proved less effective and less safe compared to genetic perturbation, limiting its potential for clinical application [<span>4</span>]. Meanwhile, mTOR, a key regulator of metabolism and a downstream target of the PI3K/AKT signaling pathway, has emerged as a promising therapeutic target for several diseases, including treatment of cancer [<span>5</span>].</p><p>In addition to identifying the contribution of mTOR signaling to BRCA1-deficient cells (Supplementary Figure S1), we provide genetic and pharmacological evidence using multi-orthogonal preclinical models [<span>6-8</span>] that mTOR is closely involved in the development and growth of <i>Brca1</i>-mutated mammary tumors (Figure 1A). To investigate the role of mTOR in the absence of BRCA1, we assessed the development of mammary glands in post-pubertal <i>Brca1/Mtor</i>-mutant mice by examining ductal and lobular development of the fourth mammary gland. Measurements of mammary gland density using the Branch software (ver. 1.1 [<span>9</span>]) showed that ductal length and branching were significantly diminished in the mammary glands of <i>Brca1<sup>co/co</sup>Mtor<sup>co/co</sup>MMTV-Cre</i> mice (Figure 1B,C, Supplementary Figure S2). To determine whether mTOR contributes to BRCA1-deficient mammary tumor formation, we examined tumor formation in cohorts of <i>Brca1<sup>co/co</sup></i> (<i>n</i> = 28), <i>Brca1<sup>co/co</sup>Mtor<sup>co/co</sup></i> (<i>n</i> = 30), <i>Brca1<sup>co/co</sup>MMTV-Cre</i> (<i>n</i> = 24), and <i>Brca1<sup>co/co</sup>Mtor<sup>co/co</sup>MMTV-Cre</i> (<i>n</i> = 29) mice (Top left of Figure 1A). <i>Brca1<sup>co/co</sup></i> and <i>Brca1<sup>co/co</sup>Mtor<sup>co/co</sup></i> mice showed no signs of mammary abnormalities, including tumors, up to 24 months of age. In contrast, <i>Brca1<sup>co/co</sup>MMTV-Cre</i> mutant mice developed breast cancer, reaching a high incidence (37.5%; 9/24) by 24 months of age. During the s
{"title":"Inhibition of mTOR attenuates the initiation and progression of BRCA1-associated mammary tumors","authors":"Hye Jung Baek, Geun Hee Han, Eun Joo Cho, Jihao Xu, Min Kyung Ki, Eun Jung Park, Tae Hyun Kim, Dong Hoon Shin, Heesun Cheong, Chu-Xia Deng, Sung Chul Lim, Chang-il Hwang, Daehee Hwang, Sang Soo Kim","doi":"10.1002/cac2.12663","DOIUrl":"10.1002/cac2.12663","url":null,"abstract":"<p>Inherited mutation in breast cancer susceptibility gene 1 (<i>BRCA1</i>) is strongly associated with mammary tumors that exhibit triple-negative characteristics, are insensitive to endocrine-targeted therapies, and show basal-like properties, including aggressive phenotypes [<span>1, 2</span>]. It has been reported that the average cumulative risk of breast cancer for <i>BRCA1</i> mutation carriers by age 70 years is 57% (95% confidence interval [CI]: 47%-66%) [<span>3</span>]. Despite the high incidence and aggressive characteristics of <i>BRCA1</i>-associated breast cancer, few substantial improvements in preventing or treating this cancer have been made, largely due to the challenges of clinic-based cohort studies. During malignant transformation, cancer progression is facilitated by metabolic reprogramming–one of the hallmark characteristics of cancer. Previously, we found that inhibition of AKT is a potential strategy for the prevention and therapeutic management of <i>Brca1</i>-mutant mammary tumors. However, pharmacological inhibition proved less effective and less safe compared to genetic perturbation, limiting its potential for clinical application [<span>4</span>]. Meanwhile, mTOR, a key regulator of metabolism and a downstream target of the PI3K/AKT signaling pathway, has emerged as a promising therapeutic target for several diseases, including treatment of cancer [<span>5</span>].</p><p>In addition to identifying the contribution of mTOR signaling to BRCA1-deficient cells (Supplementary Figure S1), we provide genetic and pharmacological evidence using multi-orthogonal preclinical models [<span>6-8</span>] that mTOR is closely involved in the development and growth of <i>Brca1</i>-mutated mammary tumors (Figure 1A). To investigate the role of mTOR in the absence of BRCA1, we assessed the development of mammary glands in post-pubertal <i>Brca1/Mtor</i>-mutant mice by examining ductal and lobular development of the fourth mammary gland. Measurements of mammary gland density using the Branch software (ver. 1.1 [<span>9</span>]) showed that ductal length and branching were significantly diminished in the mammary glands of <i>Brca1<sup>co/co</sup>Mtor<sup>co/co</sup>MMTV-Cre</i> mice (Figure 1B,C, Supplementary Figure S2). To determine whether mTOR contributes to BRCA1-deficient mammary tumor formation, we examined tumor formation in cohorts of <i>Brca1<sup>co/co</sup></i> (<i>n</i> = 28), <i>Brca1<sup>co/co</sup>Mtor<sup>co/co</sup></i> (<i>n</i> = 30), <i>Brca1<sup>co/co</sup>MMTV-Cre</i> (<i>n</i> = 24), and <i>Brca1<sup>co/co</sup>Mtor<sup>co/co</sup>MMTV-Cre</i> (<i>n</i> = 29) mice (Top left of Figure 1A). <i>Brca1<sup>co/co</sup></i> and <i>Brca1<sup>co/co</sup>Mtor<sup>co/co</sup></i> mice showed no signs of mammary abnormalities, including tumors, up to 24 months of age. In contrast, <i>Brca1<sup>co/co</sup>MMTV-Cre</i> mutant mice developed breast cancer, reaching a high incidence (37.5%; 9/24) by 24 months of age. During the s","PeriodicalId":9495,"journal":{"name":"Cancer Communications","volume":"45 4","pages":"486-490"},"PeriodicalIF":20.1,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/cac2.12663","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143000618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}