Abstract P3-07-18: Exercise and triple negative breast cancer: Unravelling the anti-neoplastic molecular factors through novel culture method
Authors: Dela Cruz MA , Roy P , Chowdhury S , Chan S , Roy HK 
Published: March 2017

Background

Despite advances to ameliorate breast cancer survival, triple negative breast cancers (TNBCs) attribute to highly disproportionate mortalities due to its aggressiveness and poor therapeutic response (Bao et al., Cancer Medicine 2014). Despite the lack of target-specific drugs, chemotherapy is the mainstay treatment, warranting more efficacious measures against TNBCs. Studies have shown that physical activity intervention reduced breast cancer risk between 20-80% (Monnikohf et. al., Epidemiology 2007) as well as breast cancer related mortality by 34% (Ibrahim et al., Med Onc 2010). However, it is clear that such intervention uptake in the population may not be feasible given the longstanding public health drive to increase physical activity. Therefore it is imperative to identify the molecular factors that might be involved in cancer prevention and therapy with the long term goal of developing a supplement. Due to the recent epidemiological findings on exercise and breast cancer, we wanted to develop a system to comprehensively identify beneficial myokines using a cell culture system.

Methods

For this study we differentiated C2C12 myoblasts into myotubules. Myotubules were contracted in Krebs Ringer Buffer solution with the C-Pace EP Pacer for 8 hours. Buffer was collected and concentrated using Amicon Ultra-0.5 centrifugal filter tubes to produced an exercise/conditioned medium. To explore the effects of exercise on breast cancer cell lines MCF-7 (ER+) and MDA-MB468 (TNBC line) were treated with conditioned medium for 48 hrs. To explore the effects of exercise and chemotherapeutic efficacy MDA-MB468 cells were treated with doxorubicin, conditioned medium or both for 48 hrs. Protein was isolated and processed for immunoblot analysis. Cell cycle markers p21, pRb, cyclin D1, PCNA as well as apoptotic marker cPARP were assessed to reveal the effects treatment.

Results

Treatment of conditioned medium in MCF-7 revealed marked changes in both p21 (92% increase, p=0.05) and pRb protein expression (62% decrease, p&lt;0.05) as well as a modest reduction in PCNA (24% decrease , p&lt;0.02). Conditioned medium treatment in MDA-MB468 cells showed a reduction in cyclin D1 and PCNA expression (40%, p&lt;0.01 and 30%, p&lt;0.02) as well as an induction of cPARP expression (32%, p=0.09). Doxorubicin treatment increased p21 and cPARP protein expression (2.2-fold increase, p&lt;0.01 and 80% increase, p&lt;0.05 respectively). Treatment of conditioned medium and doxorubicin displayed a synergistic effect with a 3.65-fold increase in p21 (p&lt;0.01) and 130% increase in cPARP (p=0.01).

Conclusions

We have developed a novel system that may enable, for the first time, mechanistic studies to elucidate the role of skeletal muscle/exercise in breast cancer prevention and chemotherapy. Our data indicates a secreted factor(s) from skeletal muscles that plays a role in anti-proliferative and pro-apoptotic effects, which are the hallmark of exercise's anti-neoplastic properties. Studies are ongoing to further understand, characterize and isolate this factor(s) for therapeutic purposes. Given the limited chemotherapeutic options and heterogeneity in TNBC, our exercise culture system sheds a promising light on novel drug development and chemo-sensitization.

Citation Format: Dela Cruz MA, Roy P, Chowdhury S, Chan S, Roy HK. Exercise and triple negative breast cancer: Unravelling the anti-neoplastic molecular factors through novel culture method [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-07-18.