Inhibition of the transition of ductal carcinoma in situ to invasive ductal carcinoma by a Gemini vitamin D analog.

Ductal carcinoma in situ (DCIS) is a nonmalignant lesion of the breast with the potential to progress to invasive ductal carcinoma (IDC). The disappearance and breakdown of the myoepithelial cell layer and basement membrane in DCIS have been identified as major events in the development of breast cancer. The MCF10DCIS.com cell line is a well-established model, which recapitulates the progression of breast cancer from DCIS to IDC. We have previously reported that a novel Gemini vitamin D analog, 1α,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-cholecalciferol (BXL0124) is a potent inhibitor of the growth of MCF10DCIS.com xenografted tumors without hypercalcemic toxicity. In this study, we utilized the MCF10DCIS.com in vivo model to assess the effects of BXL0124 on breast cancer progression from weeks 1 to 4. Upon DCIS progression to IDC from weeks 3 to 4, tumors lost the myoepithelial cell layer and basement membrane as shown by immunofluorescence staining with smooth muscle actin and laminin 5, respectively. Administration of BXL0124 maintained the critical myoepithelial cell layer as well as basement membrane, and animals treated with BXL0124 showed a 43% reduction in tumor volume by week 4. BXL0124 treatment decreased cell proliferation and maintained vitamin D receptor levels in tumors. In addition, the BXL0124 treatment reduced the mRNA levels of matrix metalloproteinases starting at week 3, contributing to the inhibition of invasive transition. Our results suggest that the maintenance of DCIS plays a significant role in the cancer preventive action of the Gemini vitamin D BXL0124 during the progression of breast lesions.

Wahler J ，So JY ，Kim YC ，Liu F ，Maehr H ，Uskokovic M ，Suh N ... -  《-》

Analysis of the Transcriptome: Regulation of Cancer Stemness in Breast Ductal Carcinoma In Situ by Vitamin D Compounds.

Ductal carcinoma in situ (DCIS), which accounts for one out of every five new breast cancer diagnoses, will progress to potentially lethal invasive ductal carcinoma (IDC) in about 50% of cases. Vitamin D compounds have been shown to inhibit progression to IDC in the MCF10DCIS model. This inhibition appears to involve a reduction in the cancer stem cell-like population in MCF10DCIS tumors. To identify genes that are involved in the vitamin D effects, a global transcriptomic analysis was undertaken of MCF10DCIS cells grown in mammosphere cultures, in which cancer stem-like cells grow preferentially and produce colonies by self-renewal and maturation, in the presence and absence of 1α25(OH)2D3 and a vitamin D analog, BXL0124. Using next-generation RNA-sequencing, we found that vitamin D compounds downregulated genes involved in maintenance of breast cancer stem-like cells (e.g., GDF15), epithelial-mesenchymal transition, invasion, and metastasis (e.g., LCN2 and S100A4), and chemoresistance (e.g., NGFR, PPP1R1B, and AGR2), while upregulating genes associated with a basal-like phenotype (e.g., KRT6A and KRT5) and negative regulators of breast tumorigenesis (e.g., EMP1). Gene methylation status was analyzed to determine whether the changes in expression induced by vitamin D compounds occurred via this mechanism. Ingenuity pathway analysis was performed to identify upstream regulators and downstream signaling pathway genes differentially regulated by vitamin D, including TP63 and vitamin D receptor -mediated canonical pathways in particular. This study provides a global profiling of changes in the gene signature of DCIS regulated by vitamin D compounds and possible targets for chemoprevention of DCIS progression to IDC in patients.

Shan NL ，Minden A ，Furmanski P ，Bak MJ ，Cai L ，Wernyj R ，Sargsyan D ，Cheng D ，Wu R ，Kuo HD ，Li SN ，Fang M ，Maehr H ，Kong AN ，Suh N ... -  《-》

A novel Gemini vitamin D analog represses the expression of a stem cell marker CD44 in breast cancer.

So JY ，Lee HJ ，Smolarek AK ，Paul S ，Wang CX ，Maehr H ，Uskokovic M ，Zheng X ，Conney AH ，Cai L ，Liu F ，Suh N ... -  《-》

HES1-mediated inhibition of Notch1 signaling by a Gemini vitamin D analog leads to decreased CD44(+)/CD24(-/low) tumor-initiating subpopulation in basal-like breast cancer.

Tumor-initiating cells (also known as cancer stem cells) are the subpopulation of cells shown to be responsible for tumor initiation, maintenance and recurrence. In breast cancer, CD44(+)/CD24(-/low) cells were identified as tumor-initiating cells. We previously reported that a Gemini vitamin D analog, 1,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-cholecalciferol (BXL0124), reduced CD44(+)/CD24(-/low) cells in MCF10DCIS basal-like breast cancer cells. Since Notch has been identified as one of the key signaling pathways involved in breast cancer stem cells, the effect of BXL0124 on the Notch signaling pathway was investigated in breast cancer. The CD44(+)/CD24(-/low) subpopulation of MCF10DCIS cells showed elevated Notch1 signaling and increased cell proliferation compared to the CD44(+)/CD24(high) subpopulation. Treatment with the Gemini vitamin D analog BXL0124 decreased the level of activated Notch1 receptor. In addition, mRNA and protein levels of the Notch ligands, Jagged-1, Jagged-2 and DLL1, were significantly reduced by treatment with BXL0124, which was followed by repression of c-Myc, a key downstream target of Notch signaling. Interestingly, HES1, a known downstream target of Notch signaling, was rapidly induced by treatment with BXL0124. The inhibitory effect of BXL0124 on Notch signaling was reversed by knockdown of HES1. Overexpression of HES1 inhibited Notch1 signaling and reduced the CD44(+)/CD24(-/low) subpopulation, confirming a role of HES1 in Notch1 signaling. In conclusion, the Gemini vitamin D analog, BXL0124, represses the tumor-initiating subpopulation by HES1-mediated inhibition of Notch1 signaling. The present study demonstrates BXL0124 as a potent inhibitor of Notch signaling to target tumor-initiating cells in basal-like breast cancer. This article is part of a Special Issue entitled "17th Vitamin D Workshop".

So JY ，Wahler J ，Das Gupta S ，Salerno DM ，Maehr H ，Uskokovic M ，Suh N ... -  《-》

Targeting CD44-STAT3 signaling by Gemini vitamin D analog leads to inhibition of invasion in basal-like breast cancer.

So JY ，Smolarek AK ，Salerno DM ，Maehr H ，Uskokovic M ，Liu F ，Suh N ... -  《PLoS One》