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The influence of glucocorticoids on the expression and activity of the transcription factors CCAAT/enhancer binding protein (C/EBP)beta and delta in skeletal muscle was examined by treating rats or cultured L6 myotubes with dexamethasone. Treatment of rats with 10 mg/kg of dexamethasone resulted in increased C/EBPbeta and delta DNA binding activity in the extensor digitorum longus muscle as determined by electrophoretic mobility shift assay (EMSA) and supershift analysis. A similar response was noticed in dexamethasone-treated myotubes. In other experiments, myocytes were transfected with a plasmid containing a promoter construct consisting of multiple C/EBP binding elements upstream of a luciferase reporter gene. Treatment of these cells with dexamethasone resulted in a fourfold increase in luciferase activity, suggesting that glucocorticoids increase C/EBP-dependent gene activation in muscle cells. In addition, dexamethasone upregulated the protein and gene expression of C/EBPbeta and delta in the myotubes in a time- and dose-dependent fashion as determined by Western blotting and real-time PCR, respectively. The results suggest that glucocorticoids increase C/EBPbeta and delta activity and expression through a direct effect in skeletal muscle.

PURPOSE Recent studies demonstrate that addition of neoadjuvant (NA) carboplatin (Cb) to anthracycline/taxane chemotherapy improves pathological complete response (pCR) in triple negative breast cancer (TNBC). Effectiveness of anthracycline-free, platinum combinations in TNBC is not well known. Here we report efficacy of NA carboplatin + docetaxel (CbD) in TNBC. PATIENTS AND METHODS The study population includes 190 patients with stage I-III TNBC treated uniformly on two independent prospective cohorts. All patients were prescribed NA chemotherapy regimen of Cb (AUC 6) + D (75mg/m2) given every 21 days × 6 cycles. Pathological complete response (pCR: no evidence of invasive tumor in the breast and axilla) and Residual Cancer Burden (RCB) were evaluated. RESULTS Among 190 patients, median tumor size was 35mm, 52% Lymph Node positive and 16% had germline BRCA1/2 mutation. The overall pCR and RCB 0+1 rates were 55% and 68%, respectively. pCR in patients with BRCA associated and wild-type TNBC were 59% and 56%, respectively (p=0.83). On multivariable analysis stage III disease was the only factor associated with a lower likelihood of achieving a pCR. 21% and 7% of patients, respectively, experienced at least one grade 3 or 4 adverse event. CONCLUSION The CbD regimen was well tolerated and yielded high pCR rates in both BRCA associated and wildtype TNBC. These results are comparable to pCR achieved with addition of Cb to anthracycline-taxane chemotherapy. Our study adds to the existing data on the efficacy of platinum agents in TNBC and supports further exploration of the CbD regimen in randomized studies.

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Minor epithelial injuries are repaired with the complex process of epithelial restitution independent of cell proliferation.

Cancer stem cells (CSCs) are implicated in resistance to ionizing radiation (IR) and chemotherapy. Honokiol, a biphenolic compound has been used in traditional Chinese Medicine for treating various ailments. In this study, we determined the ability of honokiol to enhance the sensitivity of colon CSCs to IR. The combination of honokiol and IR suppressed proliferation and colony formation while inducing apoptosis of colon cancer cells in culture. There were also reduced numbers and size of spheroids, which was coupled with reduced expression of CSC marker protein DCLK1. Flow cytometry studies confirmed that the honokiol-IR combination reduced the number of DCLK1+ cells. In addition, there were reduced levels of activated Notch-1, its ligand Jagged-1 and the downstream target gene Hes-1. Furthermore, expression of components of the Notch-1 activating γ-secretase complex, Presenilin 1, Nicastrin, Pen2 and APH-1 was also suppressed. On the other hand, the honokiol effects were mitigated when the Notch intracellular domain was expressed. To determine the effect of honokiol-IR combination on tumor growth in vivo, nude mice tumor xenografts were administered honokiol intraperitoneally and exposed to IR. The honokiol-IR combination significantly inhibited tumor xenograft growth. In addition, there were reduced levels of DCLK1 and the Notch signaling-related proteins in the xenograft tissues. Together, these data suggest that honokiol is a potent inhibitor of colon cancer growth that targets the stem cells by inhibiting the γ-secretase complex and the Notch signaling pathway. These studies warrant further clinical evaluation for the combination of honokiol and IR for treating colon cancers.

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Melanoma is an aggressive disease with limited therapeutic options. Here, we determined the effects of honokiol (HNK), a biphenolic natural compound on melanoma cells and stemness. HNK significantly inhibited melanoma cell proliferation, viability, clonogenicity and induced autophagy. In addition, HNK significantly inhibited melanosphere formation in a dose dependent manner. Western blot analyses also demonstrated reduction in stem cell markers CD271, CD166, Jarid1b, and ABCB5. We next examined the effect of HNK on Notch signaling, a pathway involved in stem cell self-renewal. Four different Notch receptors exist in cells, which when cleaved by a series of enzymatic reactions catalyzed by Tumor Necrosis Factor-α-Converting Enzyme (TACE) and γ-secretase protein complex, results in the release of the Notch intracellular domain (NICD), which then translocates to the nucleus and induces target gene expression. Western blot analyses demonstrated that in HNK treated cells there is a significant reduction in the expression of cleaved Notch-2. In addition, there was a reduction in the expression of downstream target proteins, Hes-1 and cyclin D1. Moreover, HNK treatment suppressed the expression of TACE and γ-secretase complex proteins in melanoma cells. To confirm that suppression of Notch-2 activation is critical for HNK activity, we overexpressed NICD1, NICD2, and performed HNK treatment. NICD2, but not NICD1, partially restored the expression of Hes-1 and cyclin D1, and increased melanosphere formation. Taken together, these data suggest that HNK is a potent inhibitor of melanoma cells, in part, through the targeting of melanoma stem cells by suppressing Notch-2 signaling.