Mitochondrial DNA analysis efficiently contributes to the identification of metastatic contralateral breast cancers

Oncogenic metabolic reprogramming in breast cancer: focus on signaling pathways and mitochondrial genes

Oncogenic metabolic reprogramming impacts the abundance of key metabolites that regulate signaling and epigenetics. Metabolic vulnerability in the cancer cell is evident from the Warburg effect. The research on metabolism in the progression and survival of breast cancer (BC) is under focus. Oncogenic signal activation and loss of tumor suppressor are important regulators of tumor cell metabolism. Several intrinsic and extrinsic factors contribute to metabolic reprogramming. The molecular mechanisms underpinning metabolic reprogramming in BC are extensive and only partially defined. Various signaling pathways involved in the metabolism play a significant role in the modulation of BC. Notably, PI3K/AKT/mTOR pathway, lactate-ERK/STAT3 signaling, loss of the tumor suppressor Ras, Myc, oxidative stress, activation of the cellular hypoxic response and acidosis contribute to different metabolic reprogramming phenotypes linked to enhanced glycolysis. The alterations in mitochondrial genes have also been elaborated upon along with their functional implications. The outcome of these active research areas might contribute to the development of novel therapeutic interventions and the remodeling of known drugs.

Mitochondrial DNA mutations in aging and cancer

Advancing age is a major risk factor for malignant transformation and the development of cancer. As such, over 50% of neoplasms occur in individuals over the age of 70. The pathologies of both ageing and cancer have been characterized by respective groups of molecular hallmarks, and while some features are divergent between the two pathologies, several are shared. Perturbed mitochondrial function is one such common hallmark, and this observation therefore suggests that mitochondrial alterations may be of significance in age‐related cancer development. There is now considerable evidence documenting the accumulation of somatic mitochondrial DNA (mtDNA) mutations in ageing human postmitotic and replicative tissues. Similarly, mutations of the mitochondrial genome have been reported in human cancers for decades. The plethora of functions in which mitochondria partake, such as oxidative phosphorylation, redox balance, apoptosis and numerous biosynthetic pathways, manifests a variety of ways in which alterations in mtDNA may contribute to tumour growth. However, the specific mechanisms by which mtDNA mutations contribute to tumour progression remain elusive and often contradictory. This review aims to consolidate current knowledge and describe future direction within the field.

Association of molecular subtype concordance and survival outcome in synchronous and metachronous bilateral breast cancer

Background

The aim of this study was to analyze the association of molecular subtype concordance and disease outcome in patients with synchronous bilateral breast cancer (SBBC) and metachronous breast cancer (MBBC).

Patients and methods

Patients diagnosed with SBBC or MBBC in the Surveillance, Epidemiology, and End Results (SEER) database or Comprehensive Breast Health Center (CBHC) Ruijin Hospital, Shanghai were retrospectively reviewed and included. Clinicopathologic features, molecular subtype status concordance, and prognosis were compared in patients with SBBC and MBBC. Other prognostic factors for breast cancer-specific survival (BCSS) and overall survival (OS) were also identified for bilateral breast cancer patients.

Results

Totally, 3395 and 115 patients were included from the SEER and Ruijin CBHC cohorts. Molecular subtype concordance rate was higher in the SBBC group compared to MBBC in both SEER cohort (75.8% vs 57.7%, p < 0.001) and Ruijin CBHC cohort (76.2% vs 45.2%, p = 0.002). Survival analyses indicated that SBBC was related to worse BCSS than MBBC (p = 0.015). Molecular subtype discordance was related to worse BCSS (hazard ratio (HR), 1.64, 95% confidential interval (CI), 1.18–2.27, p = 0.003) and OS (HR, 1.59, 95% CI, 1.24–2.04, p < 0.001) in the SBBC group, but not for the MBBC group (p = 0.650 for BCSS, p = 0.669 for OS).

Conclusions

Molecular subtype concordance rate was higher in the SBBC group than MBBC group. Patients with discordant molecular subtype was associated with worse disease outcome in the SBBC patients, but not in MBBC, which deserves further clinical evaluation.

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SBBC was associated with higher concordance rates of ER, PR, HER2, and molecular subtype status compared to MBBC.

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SBBC had worse BCSS than MBBC.

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Molecular subtype discordance was independently related to worse prognosis in SBBC but has no impact on prognosis of MBBC.