crt-0066101 and Triple-Negative-Breast-Neoplasms

Protein kinase D3 (PKD3) is upregulated in triple-negative breast cancer (TNBC) and associated with cell proliferation and metastasis development but its precise pro-oncogenic function is unknown. Here we show that PKD3 is required for the maintenance of the TNBC stem cell population. The depletion of PKD3 in MDA-MB-231 cells reduced the cancer stem cell frequency in vitro and tumor initiation potential in vivo. We further provide evidence that the RhoGEF GEF-H1 is upstream of PKD3 activation in TNBC stem cells. Most importantly, pharmacological PKD inhibition in combination with paclitaxel synergistically decreased oncosphere and colony formation efficiency in vitro and tumor recurrence in vivo. Based on our results we propose that targeting the GEF-H1/PKD3 signaling pathway in combination with chemotherapy might provide an effective therapeutic option for TNBC.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Drug Synergism; Female; Gene Knockdown Techniques; Humans; Mice; Neoplastic Stem Cells; Paclitaxel; Protein Kinase C; Pyrimidines; Rho Guanine Nucleotide Exchange Factors; Signal Transduction; Triple Negative Breast Neoplasms; Xenograft Model Antitumor Assays

Breast cancer is clinically classified into three main subtypes: estrogen receptor-positive (ER. The expression level of PRKDs was analyzed in breast cancer samples and breast cancer cell lines. The effects of inhibiting PRKD activity with CRT0066101 on TNBC cell proliferation, cell cycle, apoptosis, and tumor growth were studied by Cell Counting Kit8 assay, cell cycle assay, propidium iodide/annexin-V assay, and a xenograft mouse model, respectively. To uncover the molecular mechanism of CRT0066101 in TNBC, comparative phosphoproteomic analysis using iTRAQ was employed.. We found that PRKD2 and PRKD3 were preferentially expressed in breast cancers. Immunohistochemistry confirmed the overexpression of PRKD2 and PRKD3 in TNBC. CRT0066101, which inhibited the activity of PRKDs, dramatically inhibited proliferation, increased apoptosis and the G1-phase population of TNBC cells in vitro, and reduced breast tumor volume in vivo. Comparative phosphoproteomic analysis between breast cancer cells with and without CRT0066101 treatment revealed that the anti-breast cancer effects involved regulation of a complex network containing multiple enriched pathways and several hub-nodes contributing to multiple cancer-related processes, thus explaining the described effects of CRT0066101 on TNBC in vitro and in vivo. Finally, we validated several targets of PRKD inhibition by treatment with CRT0066101 and small interfering RNAs against PRKD2 and PRKD3 (siPRKD2 and siPRKD3), including p-MYC(T58/ S62), p-MAPK1/3(T202/Y204), p-AKT(S473), p-YAP(S127), and p-CDC2(T14).. PRKD inhibitor CRT0066101 exhibits anti-TNBC effects via modulating a phosphor-signaling network and inhibiting the phosphorylation of many cancer-driving factors, including MYC, MAPK1/3, AKT, YAP, and CDC2, providing insight into the important roles as well as the molecular mechanism of CRT0066101 as an effective drug for TNBC.

Topics: Animals; Apoptosis; Cell Line, Tumor; Cell Proliferation; Female; G1 Phase Cell Cycle Checkpoints; Humans; Mice; Mice, Nude; Phosphopeptides; Protein Kinase C; Proteomics; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-myc; Pyrimidines; RNA Interference; RNA, Small Interfering; Triple Negative Breast Neoplasms