Semaphorin signaling via MICAL3 induces symmetric cell division to expand breast cancer stem-like cells.

Cancer stem-like cells (CSCs) are expanded in the CSC niche by increased frequency of symmetric cell divisions at the expense of asymmetric cell divisions. The symmetric division of CSCs is important for the malignant properties of cancer; however, underlying molecular mechanisms remain largely elusive. Here, we show a cytokine, semaphorin 3 (Sema3), produced from the CSC niche, induces symmetric divisions of CSCs to expand the CSC population. Our findings indicate that stimulation with Sema3 induced sphere formation in breast cancer cells through neuropilin 1 (NP1) receptor that was specifically expressed in breast CSCs (BCSCs). Knockdown of MICAL3, a cytoplasmic Sema3 signal transducer, greatly decreased tumor sphere formation and tumor-initiating activity. Mechanistically, Sema3 induced interaction among MICAL3, collapsin response mediator protein 2 (CRMP2), and Numb. It appears that activity of MICAL3 monooxygenase (MO) stimulated by Sema3 is required for tumor sphere formation, interaction between CRMP2 and Numb, and accumulation of Numb protein. We found that knockdown of CRMP2 or Numb significantly decreased tumor sphere formation. Moreover, MICAL3 knockdown significantly decreased Sema3-induced symmetric divisions in NP1/Numb-positive BCSCs and increased asymmetric division that produces NP1/Numb negative cells without stem-like properties. In addition, breast cancer patients with NP1-positive cancer tissues show poor prognosis. Therefore, the niche factor Sema3-stimulated NP1/MICAL3/CRMP2/Numb axis appears to expand CSCs at least partly through increased frequency of MICAL3-mediated symmetric division of CSCs.

MCM10 compensates for Myc-induced DNA replication stress in breast cancer stem-like cells.

Cancer stem-like cells (CSCs) induce drug resistance and recurrence of tumors when they experience DNA replication stress. However, the mechanisms underlying DNA replication stress in CSCs and its compensation remain unclear. Here, we demonstrate that upregulated c-Myc expression induces stronger DNA replication stress in patient-derived breast CSCs than in differentiated cancer cells. Our results suggest critical roles for mini-chromosome maintenance protein 10 (MCM10), a firing (activating) factor of DNA replication origins, to compensate for DNA replication stress in CSCs. MCM10 expression is upregulated in CSCs and is maintained by c-Myc. c-Myc-dependent collisions between RNA transcription and DNA replication machinery may occur in nuclei, thereby causing DNA replication stress. MCM10 may activate dormant replication origins close to these collisions to ensure the progression of replication. Moreover, patient-derived breast CSCs were found to be dependent on MCM10 for their maintenance, even after enrichment for CSCs that were resistant to paclitaxel, the standard chemotherapeutic agent. Further, MCM10 depletion decreased the growth of cancer cells, but not of normal cells. Therefore, MCM10 may robustly compensate for DNA replication stress and facilitate genome duplication in cancer cells in the S-phase, which is more pronounced in CSCs. Overall, we provide a preclinical rationale to target the c-Myc-MCM10 axis for preventing drug resistance and recurrence of tumors.

Long-Term Physical Activity and Body Composition After Exercise and Educational Programs for Breast Cancer: A Randomized Controlled Trial From the Setouchi Breast Project-10.

BACKGROUND: It is unclear what interventions can sustain long-term higher physical activity (PA) to improve breast cancer outcomes. Thus, this study aimed to evaluate the long-term effects of interventions on PA after breast cancer treatment. METHODS: This was a prospective randomized controlled trial for patients with stage 0 to III breast cancer evaluating the efficacy of exercise and educational programs on long-term PA compared with usual care. The primary endpoint was proportion of patients with recreational PA (RPA) ≥5 metabolic equivalents (METs)/week at 1 year after registration. RESULTS: From March 16, 2016, to March 15, 2020, breast cancer patients were registered in the control (n = 120), education (n = 121), or exercise (n = 115) group. There were no significant differences in proportion of RPA ≥5 METs/week at 1 year between the exercise and control groups (54% and 53%, P = .492) and between the education and control groups (62% and 53%, P = .126). Significant difference in reductions from baseline at 1 year were noted on body weight (P = .0083), BMI (P = .0034), and body fat percentage (P = .0027) between education and control groups. Similarly, the exercise group showed significant difference in reduction in body fat percentage (P = .0038) compared to control group. CONCLUSION: Although there were no significant effects on RPA 1 year after exercise and educational programs for breast cancer survivors, both interventions reduced body composition. Future studies on PA should investigate appropriate interventions to improve overall survival.

The effect of exercise and educational programs for breast cancer patients on the development of breast cancer-related lymphoedema: secondary endpoint from a randomized controlled trial in the Setouchi Breast Project-10.

BACKGROUND: Although the association between higher physical activity and preventive effect on breast-cancer-related lymphoedema (BCRL) has been reported, it is unclear what intervention is optimal. We aimed to investigate the effect of exercise and educational programs on BCRL development. METHODS: This study was a secondary endpoint analysis from a prospective randomized controlled trial. We enrolled patients with stage 0-III breast cancer from March 2016 to March 2020 and randomly assigned them to the control (n = 111), education (n = 115), or exercise (n = 104) group. As secondary endpoint, we assessed the incidence of and preventive effect on BCRL at 12 months post-intervention. RESULTS: There were no significant differences in the incidence of BCRL at 12 months post-intervention between the exercise and control groups (9.8% and 10.8%, P = 0.83) and the education and control groups (11.6% and 10.8%, P = 1.00). There were no significant differences in time to BCRL onset from the day of surgery between the exercise and control groups (event rate at 12 months: 20.7% and 17.2%, log-rank, P = 0.54) and the education and control groups (18.8% and 17.2%, log-rank, P = 0.57). The multivariable analyses indicated that axillary dissection and obesity significantly increased the risk of BCRL [hazard ratio (HR): 2.36, 95% confidence interval (CI) 1.52-3.67 and HR: 1.68, 95% CI 1.07-2.63, respectively]. CONCLUSIONS: The intervention did not decrease the risk of BCRL, and axillary dissection and obesity were the risk factors of BCRL. TRIAL REGISTRATION NUMBER: UMIN000020595 at UMIN Clinical Trial Registry.

FXYD3 functionally demarcates an ancestral breast cancer stem cell subpopulation with features of drug-tolerant persisters.

The heterogeneity of cancer stem cells (CSCs) within tumors presents a challenge in therapeutic targeting. To decipher the cellular plasticity that fuels phenotypic heterogeneity, we undertook single-cell transcriptomics analysis in triple-negative breast cancer (TNBC) to identify subpopulations in CSCs. We found a subpopulation of CSCs with ancestral features that is marked by FXYD domain-containing ion transport regulator 3 (FXYD3), a component of the Na+/K+ pump. Accordingly, FXYD3+ CSCs evolve and proliferate, while displaying traits of alveolar progenitors that are normally induced during pregnancy. Clinically, FXYD3+ CSCs were persistent during neoadjuvant chemotherapy, hence linking them to drug-tolerant persisters (DTPs) and identifying them as crucial therapeutic targets. Importantly, FXYD3+ CSCs were sensitive to senolytic Na+/K+ pump inhibitors, such as cardiac glycosides. Together, our data indicate that FXYD3+ CSCs with ancestral features are drivers of plasticity and chemoresistance in TNBC. Targeting the Na+/K+ pump could be an effective strategy to eliminate CSCs with ancestral and DTP features that could improve TNBC prognosis.

Subcutaneous axillary primary epithelioid hemangioendothelioma: report of a rare case.

BACKGROUND: Epithelioid hemangioendothelioma (EHE) is a rare and slow-growing malignant vascular neoplasm composed of epithelioid endothelial cells within a distinctive myxohyaline stroma. It most commonly involves somatic soft tissue, lungs, liver and bone. Herein, we describe a case of EHE arising in the axillary region. CASE PRESENTATION: A 61-year-old man was under observation for multiple hepatic hemangiomas. Fluorodeoxyglucose-positron emission tomography/computed tomography showed specific uptake in a right axillary tumor. The patient was referred to our department for further investigation of the axillary tumor. An elastic-soft and poorly mobile tumor was palpable in the right axilla. Contrast-enhanced computed tomography showed a right axillary tumor and enlarged hepatic hemangiomas. In addition, multiple nodules in both lungs, a left renal angiomyolipoma, and left adrenal adenoma were revealed. Ultrasonography showed masses in both lobes of the thyroid gland, and a 30-mm lobulated hypoechoic mass in the axilla with well-defined and rough borders, showing internal heterogeneity. Fine-needle aspiration cytology was performed on the thyroid and axillary tumors: the thyroid tumor was class V, raising suspicion of papillary thyroid cancer (PTC); the left superior internal jugular node was class V, raising suspicion of metastasis of PTC; and the axillary tumor was class III, raising suspicion of a mesenchymal tumor with few epithelioid cells. The multiple lung nodules were diagnosed as metastatic tumors derived from thyroid cancer. We diagnosed these diseases as PTC of T1b(m)N1bM1(lung) Stage IVB and a right axillary tumor of unclear origin. However, it was assumed to be a primary mesenchymal tumor or a lymph node metastasis from lung cancer or occult breast cancer. We performed total thyroidectomy, left cervical lymph node dissection, and right axillary tumor excision. Histopathologic examination revealed the thyroid tumor as a PTC and the axillary tumor as an EHE. The EHE showed nuclear atypia, necrosis and high mitotic figures. Hence, it was considered to be a high-risk EHE. CONCLUSIONS: We experienced a rare primary subcutaneous axillary EHE with metastatic thyroid cancer in the lung. Since our case was classified as a high-risk EHE, a close follow-up would be appropriate.

A case of primary breast angiosarcoma with multiple discontinuous small lesions.

BACKGROUND: Angiosarcoma of the breast is rare. It carries a poor prognosis because of its high risk of local recurrence and distant metastases. Presently, there are still no established systemic therapies. Thus, the main treatment strategy for breast angiosarcoma is complete resection. This underscores the importance of closely monitoring the spread of the tumor lesion, particularly for multifocal angiosarcoma, and to plan an optimal operative procedure. We herein present the successful surgical treatment of a rare case of multifocal primary breast angiosarcoma. CASE PRESENTATION: A 43-year-old woman visited our hospital with a growing lump on her right breast accompanied by pain. Clinical and radiological examinations revealed a well-circumscribed 40-mm-diameter tumor at the inner lower quadrant of her right breast. Histological examination of a needle biopsy specimen revealed angiosarcoma. Based on a precise evaluation of the tumor by contrast-enhanced MRI and contrast-enhanced CT scan, a wide local excision with sufficient margins was performed. In the resected specimen, three discontinuous small lesions of angiosarcoma were observed around the main tumor. Therefore, total mastectomy was additionally performed. Pathological examination revealed two other small nodules of angiosarcoma in the remnant right breast, which appeared to be close but not continuous to the defective part of the initial resection. Postoperative follow-up at 1 year showed no signs of recurrence or distant metastasis. Multifocal primary breast angiosarcoma is extremely rare with only two previous reports describing its multifocality. CONCLUSIONS: Owing to its rarity, a standardized surgical treatment for breast angiosarcoma remains controversial. Our case suggests that primary breast angiosarcoma may occasionally present with multifocal tumor. Thus, it is important to keep in mind the multifocality of breast angiosarcoma when assessing its spread by diagnostic imaging and when planning the surgical strategy.

An autocrine/paracrine circuit of growth differentiation factor (GDF) 15 has a role for maintenance of breast cancer stem-like cells.

Cancer stem cells are thought to be responsible for tumor growth, recurrence, and resistance to conventional cancer therapy. However, it is still unclear how they are maintained in tumor tissues. Here, we show that the growth differentiation factor 15 (GDF15), a member of the TGFß family, may maintain cancer stem-like cells in breast cancer tissues by inducing its own expression in an autocrine/paracrine manner. We found that GDF15, but not TGFß, increased tumor sphere formation in several breast cancer cell lines and patient-derived primary breast cancer cells. As expected, TGFß strongly stimulated the phosphorylation of Smad2. GDF15 also stimulated the phosphorylation of Smad2, but the GDF15-induced tumor sphere forming efficiency was not significantly affected by treatment with SB431542, an inhibitor of the TGFß signaling. Although TGFß transiently activated ERK1/2, GDF15 induced prolonged activation of ERK1/2. Treatment with U0126, an inhibitor of the MEK-ERK1/2 signaling, greatly inhibited the GDF15-induced tumor sphere formation. Moreover, cytokine array experiments revealed that GDF15, but not TGFß, is able to induce its own expression; furthermore, it appears to form an autocrine/paracrine circuit to continuously produce GDF15. In addition, we found heterogeneous expression levels of GDF15 among cancer cells and in human breast cancer tissues using immunohistochemistry. This may reflect a heterogeneous cancer cell population, including cancer stem-like cells and other cancer cells. Our findings suggest that GDF15 induces tumor sphere formation through GDF15-ERK1/2-GDF15 circuits, leading to maintenance of GDF15high cancer stem-like cells. Targeting GDF15 to break these circuits should contribute to the eradication of tumors.