Antitumor activity of a potent MEK inhibitor, TAK-733, against colorectal cancer cell lines and patient derived xenografts

Chamaejasmin B Decreases Malignant Characteristics of Mouse Melanoma B16F0 and B16F10 Cells

Chamaejasmin B (CHB), a natural biflavone isolated from Stellera chamaejasme L., has been reported to exhibit anti-cancer properties; however, its effect in melanoma cells is not clear. Here, we aimed to investigate the anticancer effect of CHB in mouse melanoma B16F0 and B16F10 cells. We found that CHB significantly suppressed cell proliferation and promoted cell cycle arrest at G0/G1 phase in B16F0 cells; it also induced cell differentiation and increased melanin content by increasing tyrosinase (TYR) activity and mRNA levels of melanogenesis-related genes in B16F0 cells. Meanwhile, wound closure, invasion, and migration of B16F0 and B16F10 cells were dramatically inhibited. Moreover, CHB significantly increased ROS levels and decreased ΔΨm, resulting in B16F0 and B16F10 cell apoptosis. Finally, in vivo studies showed that CHB inhibited tumor growth and induced tumor apoptosis in a mouse xenograft model of murine melanoma B16F0 and B16F10 cells. Overall, CHB decreases malignant characteristics and may be a promising therapeutic agent for malignant melanoma cells via multiple signaling pathways.

Overactivation of Akt Contributes to MEK Inhibitor Primary and Acquired Resistance in Colorectal Cancer Cells

RAS and BRAF-mutated colorectal cancers are associated with resistance to chemotherapy and poor prognosis, highlighting the need for new therapeutic strategies. Although these cancers sometimes respond to mitogen activated protein kinase kinase (MEK) inhibitor treatment, they often acquire resistance via mechanisms, which are poorly understood. Here, we investigated the mechanism of MEK inhibitor resistance in primary- and acquired-resistant cells. Cell viability was examined using the trypan blue dye exclusion assay. Protein expression was analyzed by western blotting. Somatic mutations in colorectal cancer cells were investigated using the polymerase chain reaction array. PD0325901 and trametinib induced cell death in LoVo and Colo-205 cells but not in DLD-1 and HT-29 cells, which have a PIK3CA mutation constitutively activating Akt and NF-κB. Treatment with PD0325901 and trametinib suppressed ERK1/2 activation in all four cell lines but only induced Akt and NF-κB activation in DLD-1 and HT-29 cells. Inhibition of Akt but not NF-κB, overcame MEK inhibitor resistance in DLD-1 and HT-29 cells. Acquired-resistant LoVo/PR, Colo-205/PR and LoVo/TR cells have constitutively active Akt due to a M1043V mutation in the kinase activation loop of PIK3CA and Akt inhibitor resensitized these cells to MEK inhibitor. These results demonstrate that the overactivation of Akt plays a critical role in MEK inhibitor primary and acquired resistance and implicate combined Akt/MEK inhibition as a potentially useful treatment for RAS/BRAF-mutated colorectal cancer.

TAK733 attenuates adrenergic receptor-mediated cardiomyocyte hypertrophy via inhibiting ErkThr188 phosphorylation

BACKGROUND

Cardiac hypertrophy is an important risk factor for heart failure. The MEK-ERK axis has been reported as a major regulator in controlling cardiac hypertrophy. TAK733 is a potent and selective MEK inhibitor that suppresses cell growth in a broad range of cell lines.

OBJECTIVE

Therefore, we aimed to investigate the anti-hypertrophic effect of TAK733 in cardiomyocytes.

METHODS

Cardiomyocyte hypertrophy was induced with norepinephrine (NE) or phenylepinephrine (PE) using H9c2 cells. To confirm the cardiomyocyte hypertrophy, cell size and protein synthesis were measured and hypertrophy-related gene expression was estimated by reverse transcription polymerase chain reaction. To identify the signaling pathway involved, immunoblot analysis were performed.

RESULTS

We observed that NE activated MEK-ERK signaling and increased ANP and BNP expression, resulting in cardiomyocyte hypertrophy. TAK733 significantly reduced cardiomyocyte hypertrophy by regulating NE-induced ERK1/2 and ERKThr188 activation, hypertrophy marker expression, and cardiomyocyte hypertrophy through depression of MEK activity. In addition, we examined that PE-induced cardiomyocyte hypertrophy was also attenuated by TAK733.

CONCLUSIONS

Here, we report that TAK733 suppressed NE- or PE-induced cardiomyocyte hypertrophy by repressing a crucial component of cardiac hypertrophy-related pathways. These results suggest that TAK733 may be a useful therapeutics for cardiac hypertrophy and warrants further in vivo studies.

TAK-733 inhibits inflammatory neointimal formation by suppressing proliferation, migration, and inflammation in vitro and in vivo

As a potent and selective allosteric inhibitor of MEK, TAK-733 has been shown to exert anti-cancer effects for a wide range of cancers both in vitro and in vivo. However, its effects on inhibiting growth have never been investigated in the cardiovascular system, where regulation of abnormal vascular smooth muscle cell growth in neointimal hyperplasia is an important area of focus. Angiotensin II was used to mimic inflammatory neointimal hyperplasia in an in vitro environment, and balloon catheter-induced injury with an infusion of angiotensin II was used to generate an in vivo rat restenosis model under inflammatory conditions. TAK-733 exerted anti-proliferative and anti-migratory effects on human vascular smooth muscle cells. These multiple effects of TAK-733 were evaluated using various assays, such as cell cycle analysis and wound healing. Interestingly, TAK-733 did not induce apoptosis in smooth muscle cells but only reduced the proliferation rate; additionally, it did not affect EC viability. TAK-733 also exhibited anti-inflammatory activity, as observed by attenuated monocyte adhesion to smooth muscle cells via inhibition of ICAM1 and VCAM1 overexpression. The in vivo study demonstrated that neointimal hyperplasia after balloon injury and angiotensin II stimulation was suppressed by TAK-733, and downregulation of the inflammatory signal and enhanced re-endothelialization were observed. TAK-733 may have therapeutic potential for treating neointimal hyperplasia by attenuating smooth muscle cell proliferation, migration, and inflammation. Thus, TAK-733 could be a promising drug candidate for treating patients with restenosis.

Antitumor activity of the polo-like kinase inhibitor, TAK-960, against preclinical models of colorectal cancer

BACKGROUND

Polo-like kinase 1 (Plk1) is a serine/threonine kinase that is a key regulator of multiple stages of mitotic progression. Plk1 is upregulated in many tumor types including colorectal cancer (CRC) and portends a poor prognosis. TAK-960 is an ATP-competitive Plk1 inhibitor that has demonstrated efficacy across a broad range of cancer cell lines, including CRC. In this study, we investigated the activity of TAK-960 against a large collection of CRC models including 55 cell lines and 18 patient-derived xenografts.

METHODS

Fifty-five CRC cell lines and 18 PDX models were exposed to TAK-960 and evaluated for proliferation (IC50) and Tumor Growth Inhibition Index, respectively. Additionally, 2 KRAS wild type and 2 KRAS mutant PDX models were treated with TAK-960 as single agent or in combination with cetuximab or irinotecan. TAK-960 mechanism of action was elucidated through immunoblotting and cell cycle analysis.

RESULTS

CRC cell lines demonstrated a variable anti-proliferative response to TAK-960 with IC50 values ranging from 0.001 to > 0.75 μmol/L. Anti-proliferative effects were sustained after removal of drug. Following TAK-960 treatment a highly variable accumulation of mitotic (indicating cell cycle arrest) and apoptotic markers was observed. Cell cycle analysis demonstrated that TAK-960 treatment induced G2/M arrest and polyploidy. Six out of the eighteen PDX models responded to single agent TAK-960 therapy (TGII< 20). The addition of TAK-960 to standard of care chemotherapy resulted in largely additive antitumor effects.

CONCLUSION

TAK-960 is an active anti-proliferative agent against CRC cell lines and PDX models. Collectively, these data suggest that TAK-960 may be of therapeutic benefit alone or in combination with other agents, although future work should focus on the development of predictive biomarkers and hypothesis-driven rational combinations.

Evaluation of TAK-264, an Antibody-Drug Conjugate in Pancreatic Cancer Cell Lines and Patient-Derived Xenograft Models

BACKGROUND

Antibody-drug conjugates (ADCs) are an emerging technology consisting of an antibody, linker, and toxic agent, which have the potential to offer a targeted therapeutic approach. A novel target recently explored for the treatment of pancreatic cancer is guanylyl cyclase C (GCC). The objective of this study was to determine the anti-tumorigenic activity of TAK-264, an investigational ADC consisting of an antibody targeting GCC linked to a monomethyl auristatin E payload via a peptide linker.

METHODS

The antiproliferative effects of TAK-264 assessed in a panel of eleven pancreatic cancer cell lines. Additionally, ten unique pancreatic ductal adenocarcinoma cancer patient-derived xenograft models were treated with TAK-264 and the efficacy was determined. Baseline levels of GCC were analyzed on PDX models and cell lines. Immunoblotting was performed to evaluate the effects of TAK-264 on downstream effectors.

RESULTS

GCC protein expression was analyzed by immunoblotting in both normal and tumor tissue; marked increase in GCC expression was observed in tumor tissue. The in vitro experiments demonstrated a range of responses to TAK-264. Eight of the ten PDAC PDX models treated with TAK-264 demonstrated a statistically significant tumor growth inhibition. Immunoblotting demonstrated an increase in phosphorylated-HistoneH3 in both responsive and less responsive cell lines and PDAC PDX models treated with TAK-264. There was no correlation between baseline levels of GCC and response in either PDX or cell line models.

CONCLUSION

TAK-264 has shown suppression activity in pancreatic cancer cell lines and in pancreatic PDX models. These findings support further investigation of ADC targeting GCC.

Photoactivation provides a mechanistic explanation for pan-assay interference behaviour of 2-aminopyrroles in lipoxygenase inhibition

Human 15-lipoxygenase-1 (h-15-LOX-1) is a promising drug target in inflammation and cancer. In this study substitution-oriented screening (SOS) has been used to identify compounds with a 2-aminopyrrole scaffold as inhibitors for h-15-LOX-1. The observed structure activity relationships (SAR) proved to be relatively flat. IC₅₀'s for the most potent inhibitor of the series did not surpass 6.3 μM and the enzyme kinetics demonstrated uncompetitive inhibition. Based on this, we hypothesized that the investigated 2-aminopyrroles are pan assay interference compounds (PAINS) with photoactivation via a radical mechanism. Our results demonstrated clear photoactivation of h-15-LOX-1 inhibition under UV and visible light. In addition, the investigated 2-aminopyrroles decreased viability of cultured human hepatocarcinoma cells HCC-1.2 in a dose-dependent manner with LD₅₀ ranging from 0.55 ± 0.15 μM (21B10) to 2.75 ± 0.91 μM (22). Taken together, this indicates that photoactivation can play an important role in the biological activity of compounds with a 2-amino-pyrrole scaffold as investigated here.

Development and Maintenance of a Preclinical Patient Derived Tumor Xenograft Model for the Investigation of Novel Anti-Cancer Therapies

Patient derived tumor xenograft (PDTX) models provide a necessary platform in facilitating anti-cancer drug development prior to human trials. Human tumor pieces are injected subcutaneously into athymic nude mice (immunocompromised, T cell deficient) to create a bank of tumors and subsequently are passaged into different generations of mice in order to maintain these tumors from patients. Importantly, cellular heterogeneity of the original tumor is closely emulated in this model, which provides a more clinically relevant model for evaluation of drug efficacy studies (single agent and combination), biomarker analysis, resistant pathways and cancer stem cell biology. Some limitations of the PDTX model include the replacement of the human stroma with mouse stroma after the first generation in mice, inability to investigate treatment effects on metastasis due to the subcutaneous injections of the tumors, and the lack of evaluation of immunotherapies due to the use of immunocompromised mice. However, even with these limitations, the PDTX model provides a powerful preclinical platform in the drug discovery process.