ldn-193189 and Colorectal-Neoplasms

Despite new agent development and short-term benefits in patients with colorectal cancer (CRC), metastatic CRC cure rates have not improved due to high rates of 5-fluorouracil (5-FU)/leucovorin/oxaliplatin (FOLFOX)-resistance and a clinical therapeutic plateau. At the same time, this treatment regime leads to significant toxicity, cost, and patient inconvenience. Drug-resistance is linked to CRC stem cells, which are associated with the epidermal-to-mesenchymal transition (EMT) pathway. Thus, to optimally treat CRC, a therapy that can target the cell survival and EMT pathways in both CRC bulk and stem cell populations is critical. We recently identified a novel small molecule NSC30049 (7a) that is effective alone, and in combination potentiates 5-FU-mediated growth inhibition of CRC bulk, FOLFOX-resistant, and CRC stem cells both in vitro and in vivo models. In the present study, we report the synthesis and anti-CRC evaluation of several stable and effective 7a analogs. ASR352 (7b) was identified as one of the equipotent 7a analogs that inhibited the growth of CRC bulk cells, sensitized FOLFOX-resistant cells, and reduced the sphere formation capacity of CRC stem cells. It appears that the complex mechanism of cytotoxicity for 7b includes abrogation of 5-FU-induced the S phase, reduction of the phosphorylation of Chk1 at S317P, S345P and S296P, increased γH2AX staining, activation of caspase 3/PARP1 cleavage, and enhancement of Bax/Bcl2 ratio. Further 7b-mediated reduced phosphorylation of Chk1 was an indirect effect, since it did not inhibit Chk1 activity in an in vitro kinase assay. Our findings suggest that 7b as a single agent, or in combination with 5-FU can be developed as a therapeutic agent in CRC bulk, FOLFOX-resistant, and CRC stem cell populations for unmanageable metastatic CRC conditions.

Topics: Adamantane; Antineoplastic Agents; Aza Compounds; Cell Proliferation; Cell Survival; Colorectal Neoplasms; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Fluorouracil; HCT116 Cells; HT29 Cells; Humans; Molecular Structure; Oxaliplatin; Stem Cells; Structure-Activity Relationship; Tumor Cells, Cultured

Poor prognoses for colorectal cancer patients with metastatic lesions have driven demand for the development of novel targeted therapies. Here, we demonstrate that expression of bone morphogenetic protein 4 (BMP-4) is universally upregulated in human colorectal cancer cells and tissues, resulting in activated BMP signaling. Inhibition of endogenous BMP signaling by the BMP type I receptor inhibitor LDN-193189 elevated expression of the phosphatase DUSP5 in colorectal cancer cells, inducing apoptosis via dephosphorylation of Erk MAPK. Administering LDN-193189 to mice diminished tumor formation of colorectal cancer cells. Our findings suggest inhibition of autocrine BMP-4 as a candidate treatment strategy for colorectal cancer.

Topics: Animals; Antineoplastic Agents; Apoptosis; Autocrine Communication; Bone Morphogenetic Protein 4; Cell Line, Tumor; Colorectal Neoplasms; Female; Gene Knockdown Techniques; Humans; Immunoblotting; Immunohistochemistry; In Situ Nick-End Labeling; Mice; Mice, Inbred BALB C; Mice, Nude; Pyrazoles; Pyrimidines; Real-Time Polymerase Chain Reaction; Xenograft Model Antitumor Assays

Aberrant activation of WNT signalling and loss of BMP signals represent the two main alterations leading to the initiation of colorectal cancer (CRC). Here we screen for genes required for maintaining the tumour stem cell phenotype and identify the zinc-finger transcription factor GATA6 as a key regulator of the WNT and BMP pathways in CRC. GATA6 directly drives the expression of LGR5 in adenoma stem cells whereas it restricts BMP signalling to differentiated tumour cells. Genetic deletion of Gata6 from mouse colon adenomas increases the levels of BMP factors, which signal to block self-renewal of tumour stem cells. In human tumours, GATA6 competes with β-catenin/TCF4 for binding to a distal regulatory region of the BMP4 locus that has been linked to increased susceptibility to development of CRC. Hence, GATA6 creates an environment permissive for CRC initiation by lowering the threshold of BMP signalling required for tumour stem cell expansion.

Topics: Adenoma; Animals; Antineoplastic Agents; Bone Morphogenetic Protein Receptors; Cell Proliferation; Colorectal Neoplasms; Female; Fluorescent Antibody Technique; GATA6 Transcription Factor; Gene Expression Regulation, Neoplastic; Humans; Male; Mice; Pyrazoles; Pyrimidines; Stem Cells; Wnt Proteins