Antitumor activity of paclitaxel is significantly enhanced by a novel proapoptotic agent in non–small cell lung cancer

miRNAs and exosomal miRNAs in lung cancer: New emerging players in tumor progression and therapy response

Non-coding RNAs have shown key roles in cancer and among them, short RNA molecules are known as microRNAs (miRNAs). These molecules have length less than 25 nucleotides and suppress translation and expression. The functional miRNAs are produced in cytoplasm. Lung cancer is a devastating disease that its mortality and morbidity have undergone an increase in recent years. Aggressive behavior leads to undesirable prognosis and tumors demonstrate abnormal proliferation and invasion. In the present review, miRNA functions in lung cancer is described. miRNAs reduce/increase proliferation and metastasis. They modulate cell death and proliferation. Overexpression of oncogenic miRNAs facilitates drug resistance and radio-resistance in lung cancer. Tumor microenvironment components including macrophages and cancer-associated fibroblasts demonstrate interactions with miRNAs in lung cancer. Other factors such as HIF-1α, lncRNAs and circRNAs modulate miRNA expression. miRNAs have also value in the diagnosis of lung cancer. Understanding such interactions can pave the way for developing novel therapeutics in near future for lung cancer patients.

New Visions on Natural Products and Cancer Therapy: Autophagy and Related Regulatory Pathways

Macroautophagy (autophagy) has been a highly conserved process throughout evolution and allows cells to degrade aggregated/misfolded proteins, dysfunctional or superfluous organelles and damaged macromolecules, in order to recycle them for biosynthetic and/or energetic purposes to preserve cellular homeostasis and health. Changes in autophagy are indeed correlated with several pathological disorders such as neurodegenerative and cardiovascular diseases, infections, cancer and inflammatory diseases. Conversely, autophagy controls both apoptosis and the unfolded protein response (UPR) in the cells. Therefore, any changes in the autophagy pathway will affect both the UPR and apoptosis. Recent evidence has shown that several natural products can modulate (induce or inhibit) the autophagy pathway. Natural products may target different regulatory components of the autophagy pathway, including specific kinases or phosphatases. In this review, we evaluated ~100 natural compounds and plant species and their impact on different types of cancers via the autophagy pathway. We also discuss the impact of these compounds on the UPR and apoptosis via the autophagy pathway. A multitude of preclinical findings have shown the function of botanicals in regulating cell autophagy and its potential impact on cancer therapy; however, the number of related clinical trials to date remains low. In this regard, further pre-clinical and clinical studies are warranted to better clarify the utility of natural compounds and their modulatory effects on autophagy, as fine-tuning of autophagy could be translated into therapeutic applications for several cancers.

Trifluoperazine and Its Analog Suppressed the Tumorigenicity of Non-Small Cell Lung Cancer Cell; Applicability of Antipsychotic Drugs to Lung Cancer Treatment

Despite significant advances in diagnostic and therapeutic technologies, lung cancer remains the leading cause of cancer-related mortality worldwide. Non-small cell lung cancer (NSCLC) accounts for approximately 85% of lung cancer cases. Recently, some antipsychotics have been shown to possess anticancer activity. However, the effects of antipsychotics on NSCLC need to be further explored. We examined the effects of trifluoperazine (TFP), a commonly used antipsychotic drug, and its synthetic analogs on A549 human lung cancer cells. In addition, cell proliferation analysis, colony formation assay, flow cytometry, western blot analysis, and in vivo xenograft experiments were performed. Key genes and mechanisms possibly affected by TFP are significantly related to better survival outcomes in lung cancer patients. Treatment with TFP and a selected TFP analog 3dc significantly inhibited the proliferation, anchorage-dependent/independent colony formation, and migration of A549 cells. Treatment with 3dc affected the expression of genes related to the apoptosis and survival of A549 cells. Treatment with 3dc promoted apoptosis and DNA fragmentation. In all experiments, including in vivo studies of metastatic lung cancer development, 3dc had more substantial anticancer effects than TFP. According to our analysis of publicly available clinical data and in vitro and in vivo experiments, we suggest that some kinds of antipsychotics prevent the progression of NSCLC. Furthermore, this study indicates a synthetic TFP analog that could be a potential therapeutic for lung cancer.

Evaluation of a procaspase-3 activator with hydroxyurea or temozolomide against high-grade meningioma in cell culture and canine cancer patients

BACKGROUND

High-grade meningioma is an aggressive type of brain cancer that is often recalcitrant to surgery and radiotherapy, leading to poor overall survival. Currently, there are no FDA-approved drugs for meningioma, highlighting the need for new therapeutic options, but development is challenging due to the lack of predictive preclinical models.

METHODS

To leverage the known overexpression of procaspase-3 in meningioma, PAC-1, a blood-brain barrier penetrant procaspase-3 activator, was evaluated for its ability to induce apoptosis in meningioma cells. To enhance the effects of PAC-1, combinations with either hydroxyurea or temozolomide were explored in cell culture. Both combinations were further investigated in small groups of canine meningioma patients and assessed by MRI, and the novel apoptosis tracer, [18F]C-SNAT4, was evaluated in patients treated with PAC-1 + HU.

RESULTS

In meningioma cell lines in culture, PAC-1 + HU are synergistic while PAC-1 + TMZ show additive-to-synergistic effects. In canine meningioma patients, PAC-1 + HU led to stabilization of disease and no change in apoptosis within the tumor, whereas PAC-1 + TMZ reduced tumor burden in all three canine patients treated.

CONCLUSIONS

Our results suggest PAC-1 + TMZ as a potentially efficacious combination for the treatment of human meningioma, and also demonstrate the utility of including pet dogs with meningioma as a means to assess anticancer strategies for this common brain tumor.

MiR-221-3p-mediated downregulation of MDM2 reverses the paclitaxel resistance of non-small cell lung cancer in vitro and in vivo

MicroRNAs (miRNAs) are involved in the initiation and development of cancer and participate in drug resistance. Paclitaxel (PTX) is a first-line chemotherapy drug for advanced non-small cell lung cancer (NSCLC). The abnormal miRNA expression in NSCLC and its association with chemotherapy drug resistance remains largely unknown. The study aimed to investigate the aberrant expression of miR-221-3p in NSCLC and to elucidate its molecular mechanisms in relation to PTX resistance. PTX increased miR-221-3p expression and regulated MDM2/P53 expression in the PTX-sensitive NSCLC strain (A549). Meanwhile, miR-221-3p was rarely expressed and not interfered by PTX in PTX-resistant A549 cells (A549/Taxol). Dual-luciferase reporter assay confirmed that miR-221-3p specifically binds to MDM2 messenger RNA and inhibited MDM2 expression. The expression of MDM2 and P53 showed a negative correlation in NSCLC cell lines. MiR-221-3p down-regulation reduced the sensitivity of A549 cells to PTX, whereas its up-regulation partially reversed the A549/Taxol cells resistance to PTX and increased the chemosensitivity of A549/Taxol cells to PTX in xenograft models. Quantitative polymerase chain reaction analysis revealed that miR-221-3p expression increased, whereas the MDM2 level decreased in human NSCLC tumor tissues. Moreover, Western bolt analysis showed that P53 was lowly expressed in tumor tissues with MDM2 overexpression. Low expression of miR-221-3p in NSCLC tissues might indicate a poor T staging. In conclusion, miR-221-3p overexpression could regulate MDM2/p53 signaling pathway to reverse the PTX resistance of NSCLC and induce apoptosis in vitro and vivo.

Overexpression of hsa_circ_0002874 promotes resistance of non-small cell lung cancer to paclitaxel by modulating miR-1273f/MDM2/p53 pathway

Background: This study aimed to investigate the aberrant expression of hsa_circ_0002874 in non-small cell lung cancer (NSCLC) and elucidate associated molecular mechanisms that influence apoptosis and induce paclitaxel (PTX) resistance.

Methods: Inhibitors were used to downregulate circRNA or miRNA expression. pCDNA plasmid transfection and mimics were used to upregulate circRNA or miRNA expression. Dual-luciferase reporter assays were conducted to evaluate interactions between miR1273f and MDM2. Xenograft tumor models were used to assess the effect of hsa_circ_0002874 and miR1273f on tumor growth. NSCLC tissues and matched non-cancerous tissues were also collected for correlation analysis.

Results: hsa_circ_0002874 acts as a sponge for miR1273f which targets MDM2/P53. The stability of the hsa_circ_0002874/miR1273f/MDM2/P53 pathway was verified by upregulating and downregulating the expression of hsa_circ_0002874 and miR1273f. hsa_circ_0002874 downregulation or miR1273f upregulation reversed the resistance of the A549/Taxol cells in xenograft models. The expression of hsa_circ_0002874 was high, and the level of MDM2 was low in NSCLC tissues. P53 was only weakly expressed in NSCLC tissues with high expression of MDM2.

Conclusions: hsa_circ_0002874 is strongly expressed in NSCLC tissues and maybe a potential marker for PTX resistance. hsa_circ_0002874 downregulation could regulate miR1273f/MDM2/P53 signaling pathway to reverse the PTX resistance of NSCLC and induce apoptosis in vitro and vivo.

New Procaspase Activating Compound (PAC-1) Like Molecules as Potent Antitumoral Agents Against Lung Cancer

Background:

In this study, novel ortho-hydroxy N-acyl hydrazone moiety including compounds (3a-l) were designed, based on procaspase activating compound (PAC-1) which is a small molecule known with antitumor activity. The antitumor activity was evaluated on A549 (human lung cancer cell line) and CCD 19Lu (human lung normal cell line).

Methods:

Twelve N'-arylidene-2-[4-(methylsulfonyl)piperazin-1-yl]acetohydrazide derivatives (3a-l) were synthesized starting from ethyl 1-piperazinylacetate. All compounds were tested using MTT method and Xcelligence-Real time cell analysis system (RTCA DP) to determine their antitumor activity.

Results:

Some physicochemical properties of four active compounds were also predicted using MolSoft, PreADMET and PROTOX software. Four of them, 3h, 3j, 3k and 3l bearing 3-hydroxy, 4-dimethylamino, 2,6-dichloro and 3,4-dichloro substituents in order exhibited selective cytotoxicity.

Conclusion:

Eligible values were obtained in the specified ranges as to be an oral/intravenous drug considering the physicochemical calculations.

Overcoming Resistance to Targeted Anticancer Therapies through Small-Molecule-Mediated MEK Degradation

The discovery of mutant or fusion kinases that drive oncogenesis, and the subsequent approval of specific inhibitors for these enzymes, has been instrumental in the management of some cancers. However, acquired resistance remains a significant problem in the clinic, limiting the long-term effectiveness of most of these drugs. Here we demonstrate a general strategy to overcome this resistance through drug-induced MEK cleavage (via direct procaspase-3 activation) combined with targeted kinase inhibition. This combination effect is shown to be general across diverse tumor histologies (melanoma, lung cancer, and leukemia) and driver mutations (mutant BRAF or EGFR, fusion kinases EML4-ALK and BCR-ABL). Caspase-3-mediated degradation of MEK kinases results in sustained pathway inhibition and substantially delayed or eliminated resistance in cancer cells in a manner far superior to combinations with MEK inhibitors. These data suggest the generality of drug-mediated MEK kinase cleavage as a therapeutic strategy to prevent resistance to targeted anticancer therapies.

Establishment and evaluation of the VX2 orthotopic lung cancer rabbit model: a ultra-minimal invasive percutaneous puncture inoculation method

The purpose of the present work is to establish an ultra-minimal invasive percutaneous puncture inoculation method for a VX2 orthotopic lung cancer rabbit model with fewer technical difficulties, lower mortality of rabbits, a higher success rate and a shorter operation time, to evaluate the growth, metastasis and apoptosis of tumor by CT scans, necropsy, histological examination, flow cytometry and immunohistochemistry. The average inoculation time was 10–15 min per rabbit. The tumor-bearing rate was 100%. More than 90% of the tumor-bearing rabbits showed local solitary tumor with 2–10 mm diameters after two weeks post-inoculation, and the rate of chest seeding was only 8.3% (2/24). The tumors diameters increased to 4–16 mm, and irregularly short thorns were observed 3 weeks after inoculation. Five weeks post-inoculation, the liquefaction necrosis and a cavity developed, and the size of tumor grew further. Before natural death, the CT images showed that the tumors spread to the chest. The flow cytometry and immunohistochemistry indicated that there was less apoptosis in VX2 orthotopic lung cancer rabbit model compared to chemotherapy drug treatment group. Minimal invasive percutaneous puncture inoculation is an easy, fast and accurate method to establish the VX2 orthotopic lung cancer rabbit model, an ideal in situ tumor model similar to human malignant tumor growth.

The antitumour effects of eudesmin on lung cancer by inducing apoptosis via mitochondria-mediated pathway in the tumour cells

CONTEXT

Limonoids possess broad range of biological activities, including antitumour, antimicrobial and antioxidant activities, etc. Eudesmin (EDN) is a type of limonoid which also possesses various activities. However, there is no report on the antitumour lung cancer (LC) activities of this compound.

OBJECTIVE

The present study investigates the antitumour effects of EDN and its potential molecular mechanisms.

MATERIALS AND METHODS

The in vitro antitumour effects of EDN on LC A549 cells were evaluated by using MTT assay. The in vivo antitumour effects were investigated on a xenograft athymic nude mouse model. The mice were administered orally with EDN (10, 20 and 40 mg/kg) once daily for 28 days. Effects of EDN on apoptosis-related or signalling proteins (Bcl-2, Bax, caspase-3, caspase-9, P53, Akt and JNK) were assayed by western blot analysis.

RESULTS

EDN showed significant inhibitory effects on the growth of LC A549 cells in vitro with the half maximal inhibitory concentration (IC₅₀) of 18.3 μM. By treating with EDN (10, 20 and 40 μM), expression of caspase-3, caspase-9, Bax, P53 and phosphorylated JNK in A549 cells were significantly upregulated, whereas expression of Bcl-2 and Akt phosphorylation were significantly down-regulated. Interestingly, EDN-induced apoptosis could be attenuated by JNK inhibitor. In addition, in vivo experiments also indicated EDN (10, 20 and 40 mg/kg) had significant antitumour effects (p < 0.01) on nude mice.

CONCLUSIONS

Overall, the results indicated that EDN possesses significant antitumour effects on LC and the possible mechanism might be related to induction of mitochondria-mediated apoptosis.

Enhanced antitumor effect on intrapulmonary tumors of docetaxel lung-targeted liposomes in a rabbit model of VX2 orthotopic lung cancer

Allergic reactions and severe systemic toxicity are two major challenges for the clinical application of docetaxel (DTX) for treatment of non-small-cell lung cancer (NSCLC). We developed a novel lung-targeted DTX-loaded liposome (DTX-LP), an efficient drug delivery system, with a patented DBaumNC technology to overcome these deficiencies. In the present study, we describe the targeting activity, tumor inhibition rate (TIR), survival, pathology, tumor apoptosis and metabolism of DTX after intravenous injection of DTX-LP compared to the DTX injection (DTX-IN) formulation based on the VX2 orthotopic lung cancer rabbit model. Biodistribution studies revealed the highest accumulation in lung and tumor within 12 h after the injection of DTX-LP. The increased TIR indicates that the growth of tumor was slowed. Pathology tests demonstrated that DTX-LP can reduce metastasis and toxicity to non-targeted organs, leading to greatly extended survival time and improved survival of tumor-bearing rabbits. Flow cytometry and immunohistochemistry confirmed that DTX-LP is highly efficacious in tumor tissue, leading to a significant increase of tumor apoptosis and decrease of proliferation and angiogenesis. The results from this study demonstrate the increased intrapulmonary tumor targeting activity, enhanced antitumor effect and reduced toxicity of DTX-LP compared to DTX-IN and highlight its clinical prospects for NSCLC therapy.

Synergistic anticancer effects of andrographolide and paclitaxel against A549 NSCLC cells

CONTEXT

Paclitaxel (PTX) is widely used in chemotherapy for cancer treatment; however, it has some serious side effects. Andrographolide (Andro) is a potential cancer therapeutic agent isolated from Andrographis paniculata (Burm. f.) Nees (Acanthaceae).

OBJECTIVE

The objective of this study is to evaluate the effects of PTX combined with Andro against A549 cells.

MATERIALS AND METHODS

The effects of 24-48 h treatment with 0.48-60.75 nM PTX and 5.10-328.0 μM Andro on cellular proliferation, apoptosis, cell cycle and intracellular reactive oxygen species (ROS) were determined by sulphorhodamine B assay, Annexin V-FITC/PI apoptosis detection, PI staining and ROS assay, respectively. Synergy was determined using combination index. The antitumour efficacy of 20 mg/kg PTX with 100 mg/kg Andro was studied in a xenograft murine model.

RESULTS

IC₅₀ value of the PTX combined with Andro against A549 cells was 0.5-7.4 nM, which was significantly lower than that of PTX (15.9 nM). PTX with 10 μM Andro caused (1.22-1.27)-fold apoptosis and 1.7-fold ROS accumulation compared with PTX alone. N-Acetylcysteine, a ROS scavenger, blocked this synergy in vitro. In contrast, G2/M phase cell cycle arrest resulting from PTX was not potentiated by Andro. Moreover, PTX in combination with Andro inhibited the growth of A549 transplanted tumours by 98%.

DISCUSSION AND CONCLUSION

The results indicate that the combination of PTX and Andro exert significant synergistic anticancer effect on A549 cells in vitro and in vivo. The synergy may be the result of the accumulation of ROS. The combination of Andro and PTX represents a potential strategy for the treatment of A549 cells.

Small-Molecule Procaspase-3 Activation Sensitizes Cancer to Treatment with Diverse Chemotherapeutics

Conventional chemotherapeutics remain essential treatments for most cancers, but their combination with other anticancer drugs (including targeted therapeutics) is often complicated by unpredictable synergies and multiplicative toxicities. As cytotoxic anticancer chemotherapeutics generally function through induction of apoptosis, we hypothesized that a molecularly targeted small molecule capable of facilitating a central and defining step in the apoptotic cascade, the activation of procaspase-3 to caspase-3, would broadly and predictably enhance activity of cytotoxic drugs. Here we show that procaspase-activating compound 1 (PAC-1) enhances cancer cell death induced by 15 different FDA-approved chemotherapeutics, across many cancer types and chemotherapeutic targets. In particular, the promising combination of PAC-1 and doxorubicin induces a synergistic reduction in tumor burden and enhances survival in murine tumor models of osteosarcoma and lymphoma. This PAC-1/doxorubicin combination was evaluated in 10 pet dogs with naturally occurring metastatic osteosarcoma or lymphoma, eliciting a biologic response in 3 of 6 osteosarcoma patients and 4 of 4 lymphoma patients. Importantly, in both mice and dogs, coadministration of PAC-1 with doxorubicin resulted in no additional toxicity. On the basis of the mode of action of PAC-1 and the high expression of procaspase-3 in many cancers, these results suggest the combination of PAC-1 with cytotoxic anticancer drugs as a potent and general strategy to enhance therapeutic response.

The Combination of Vemurafenib and Procaspase-3 Activation Is Synergistic in Mutant BRAF Melanomas

The development of vemurafenib resistance limits the long-term efficacy of this drug for treatment of metastatic melanomas with the (V600E)BRAF mutation. Inhibition of downstream MAPK signaling with vemurafenib induces apoptotic cell death mediated by caspase-3, suggesting that addition of a procaspase-3 activator could enhance anticancer effects. Here, we show that the combination of PAC-1, a procaspase-activating compound, and vemurafenib is highly synergistic in enhancing caspase-3 activity and apoptotic cell death in melanoma cell lines harboring the (V600E)BRAF mutation. In vivo, the combination displays a favorable safety profile in mice and exerts significant antitumor effects. We further demonstrate that addition of PAC-1 to the clinically useful combination of vemurafenib and a MEK inhibitor, trametinib, starkly enhances the caspase-3 activity and proapoptotic effect of the combination. Moreover, addition of low concentration PAC-1 also delays the regrowth of cells following treatment with vemurafenib. Finally, PAC-1 remains potent against vemurafenib-resistant A375VR cells in cell culture and synergizes with vemurafenib to exert antitumor effects on A375VR cell growth in vivo Collectively, our data suggest that inhibition of MAPK signaling combined with concurrent procaspase-3 activation is an effective strategy to enhance the antitumor activity of vemurafenib and mitigate the development of resistance. Mol Cancer Ther; 15(8); 1859-69. ©2016 AACR.

Construction of novel pH-sensitive hybrid micelles for enhanced extracellular stability and rapid intracellular drug release

Novel pH-sensitive hybrid micelles with high entrapment efficiency were constructed to realize rapid intracellular drug release without premature release.

Derivatives of Procaspase-Activating Compound 1 (PAC-1) and their Anticancer Activities

PAC-1 induces the activation of procaspase-3 in vitro and in cell culture by chelation of inhibitory labile zinc ions via its ortho-hydroxy-N-acylhydrazone moiety. First reported in 2006, PAC-1 has shown promise in cell culture and animal models of cancer, and a Phase I clinical trial in cancer patients began in March 2015 (NCT02355535). Because of the considerable interest in this compound and a well-defined structure-activity relationship, over 1000 PAC-1 derivatives have been synthesized in an effort to vary pharmacological properties such as potency and pharmacokinetics. This article provides a comprehensive examination of all PAC-1 derivatives reported to date. A survey of PAC-1 derivative libraries is provided, with an indepth discussion of four derivatives on which extensive studies have been performed.

Enhanced delivery of Paclitaxel using electrostatically-conjugated Herceptin-bearing PEI/PLGA nanoparticles against HER-positive breast cancer cells

We have developed a novel nanoparticle delivery system fabricated from polyethylenimine (PEI) and poly(d,l-lactide-co-glycolide) (PLGA), which were able to deliver the chemotherapeutic agent Paclitaxel, while the biomacromolecule Herceptin acted as a targeting ligand that was conjugated onto the surfaces of the nanoparticles via electrostatic interactions. In this study, these electrostatically-conjugated Herceptin-bearing PEI/PLGA nanoparticles (eHER-PPNs) were optimized and employed as vectors to target HER2-positive breast cancer cells. The eHER-PPNs had an average diameter of ∼ 280 nm and a neutral surface charge (1.00 ± 0.73 mV), which remained stable under physiological conditions. The anticancer effects of eHER-PPNs were investigated in HER2-positive BT474 cells and HER2-negative MCF7 cells. The eHER-PPNs showed enhanced cytotoxicity that was dependent on the receptor expression levels and the incubation time. These conjugated nanoparticles deliver Paclitaxel more efficiently (p<0.001) than unmodified PPNs, Herceptin and the combined effects of these two monotherapies. Furthermore, the chemically-conjugated Herceptin-bearing PEI/PLGA nanoparticles (cHER-PPNs) were fabricated as a comparison. The eHER-PPNs exhibited lower cell viability (46.7%) than that of cHER-PPNs (65.1%). The targeting ability of eHER-PPNs was demonstrated through confocal microscopy images and flow cytometry, which showed that eHER-PPNs displayed higher cellular uptake efficiency (p<0.001) in comparison with cHER-PPNs. Therefore, eHER-PPNs could provide promising platforms for the delivery of therapeutic drugs against HER2-positive breast cancers.

MicroRNA-7 Compromises p53 Protein-dependent Apoptosis by Controlling the Expression of the Chromatin Remodeling Factor SMARCD1

We previously demonstrated that the epidermal growth factor receptor (EGFR) up-regulated miR-7 to promote tumor growth during lung cancer oncogenesis. Several lines of evidence have suggested that alterations in chromatin remodeling components contribute to cancer initiation and progression. In this study, we identified SMARCD1 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily d, member 1) as a novel target gene of miR-7. miR-7 expression reduced SMARCD1 protein expression in lung cancer cell lines. We used luciferase reporters carrying wild type or mutated 3'UTR of SMARCD1 and found that miR-7 blocked SMARCD1 expression by binding to two seed regions in the 3'UTR of SMARCD1 and down-regulated SMARCD1 mRNA expression. Additionally, upon chemotherapy drug treatment, miR-7 down-regulated p53-dependent apoptosis-related gene BAX (BCL2-associated X protein) and p21 expression by interfering with the interaction between SMARCD1 and p53, thereby reducing caspase3 cleavage and the downstream apoptosis cascades. We found that although SMARCD1 sensitized lung cancer cells to chemotherapy drug-induced apoptosis, miR-7 enhanced the drug resistance potential of lung cancer cells against chemotherapy drugs. SMARCD1 was down-regulated in patients with non-small cell lung cancer and lung adenocarcinoma cell lines, and SMARCD1 and miR-7 expression levels were negatively correlated in clinical samples. Our investigation into the involvement of the EGFR-regulated microRNA pathway in the SWI/SNF chromatin remodeling complex suggests that EGFR-mediated miR-7 suppresses the coupling of the chromatin remodeling factor SMARCD1 with p53, resulting in increased chemo-resistance of lung cancer cells.

Removal of Metabolic Liabilities Enables Development of Derivatives of Procaspase-Activating Compound 1 (PAC-1) with Improved Pharmacokinetics

Procaspase-activating compound 1 (PAC-1) is an o-hydroxy-N-acylhydrazone that induces apoptosis in cancer cells by chelation of labile inhibitory zinc from procaspase-3. PAC-1 has been assessed in a wide variety of cell culture experiments and in vivo models of cancer, with promising results, and a phase 1 clinical trial in cancer patients has been initiated (NCT02355535). For certain applications, however, the in vivo half-life of PAC-1 could be limiting. Thus, with the goal of developing a compound with enhanced metabolic stability, a series of PAC-1 analogues were designed containing modifications that systematically block sites of metabolic vulnerability. Evaluation of the library of compounds identified four potentially superior candidates with comparable anticancer activity in cell culture, enhanced metabolic stability in liver microsomes, and improved tolerability in mice. In head-to-head experiments with PAC-1, pharmacokinetic evaluation in mice demonstrated extended elimination half-lives and greater area under the curve values for each of the four compounds, suggesting them as promising candidates for further development.