Decreased Colony Formation Research Articles

Multiparametric cytotoxicity profiling reveals cell-line and ligand-dependent toxicity for pegylated gold nanoparticles (AuNP-PEG)

The highly tunable surface chemistry of gold nanoparticles (AuNPs) makes them ideal candidates for cancer treatments. Modification of AuNP surface chemistry creates linkage points for different surface coatings whose chemical structure regulates AuNP interactions with cells and thus plays a key role in AuNP cytotoxicity. This study looked at AuNPs functionalized with three polyethylene glycol (PEG) coatings, differing in end group functionality: PEG methyl terminated thiol (PEGCH3), PEG amine terminated thiol (PEGNH2), and PEG carboxylic acid terminated thiol (PEGCOOH). Cytotoxic effects were compared across three cell lines: human embryonic kidney (HEK293T/17), prostate cancer (PC-3), and ovarian cancer (SKOV3). Biochemical assays measured the effect AuNPs elicit on the ability of single cells to form colonies, metabolize thiazolyl blue tetrazolium bromide (MTT), or produce reactive oxygen species (ROS) using 2′,7′-dichlorofluorescein. Overall, AuNP-PEG particles were minimally toxic. HEK293T/17 colony formation was significantly decreased with all but PEGCOOH particle types, and PEGNH2 treatments significantly decreased colony formation for all three tested cell lines. ROS production was significantly increased when treated with 100 µg mL−1 AuNP PEGNH2 in all three cell lines, with PEGCH3 also showing increased ROS in PC-3 cells. PEGCH3 reduced metabolic function (MTT metabolism) in only SKOV3 cells, while PEGCOOH was toxic to HEK293T/17 cells at 100 µg mL−1. These results suggest that differing end group chemistry leads to modest cytotoxic profiles for each AuNP that are cell line and coating dependent. Elucidation of AuNP mechanisms of toxicity is a critical step in the evaluation of the future therapeutic potential for these particles.

CHD4 Promotes Tumor Formation, Survival, and Resistance to Genotoxic Therapeutics in TP53 Mutant T-Cell Acute Lymphoblastic Leukemia Cells through the NuRD Chromatin Remodeling Complex

T-Cell acute leukemia(T-ALL) though generally responsive to current chemotherapy remains incurable in over 50% of adult patients. Importantly, the survival for patients with TP53 mutant T-ALL disease is less than 10%. We have previously shown the role of the Methyl Binding Domain protein 2-Nucleosome Remodeling and Deacetylase (MBD2-NURD) chromatin remodeling complex in triple negative breast cancer cell growth and the role of the NuRD component, Chromatin-helicase-binding protein 4(CHD4), in tumor colony formation and genotoxic resistance in acute myeloid leukemia. In the present study, we have examined the role of specific NuRD complexes and CHD4 in T-cell acute leukemia cells with mutant TP53. The prototypical NuRD complex possesses both a histone deacetylase (HDCC) sub-complex and an ATPase chromatin remodeling sub-complex containing CHD4 linked to MBD2 or MBD3 of the HDCC. CHD4 is linked to the MBD2/3 anchors of the NuRD complex, via GATAD2A or GATAD2B. Depletion of CHD4 was found to increase the rate of apoptosis in several TP53 mutant T-ALL cell lines including Jurkat, MOLT4, RPMI and CCRF by up to 5 to 10-fold. Likewise, depletion of both MBD2 and MBD3 also increased apoptosis and sensitization to the standard genotoxic chemotherapeutic agent, cytosine arabinoside (Ara-C) but had only minimal effects in normal human CD34+ hematopoietic progenitor cells. Depletion of GATAD2B and GATAD2A by shRNA also resulted in a significantly increased survival of 60 days compared to 20 days in Scramble shRNA controls, in a xenogeneic mouse model of T-ALL. Depletion of CHD4 resulted in a profound (10 to 100-fold) decrease in colony formation of the TP53 mutant T-ALL cell lines in methylcellulose. RNA seq analyses identified the apoptosis, ferroptosis and mitophagy pathways as potential mechanisms for the striking effect of NURD disruption on colony formation. In summary, CHD4, through the NuRD complex, promotes tumor cell formation, survival and therapeutic resistance of TP53 mutant T-ALL cells. Current efforts are aimed at validating these findings in primary T-ALL cells and structure-function studies to advance development of tool compounds for disrupting the NuRD complex, with the long-term goal of developing improved small molecule therapeutics for treatment resistant acute leukemia.

Tousled-like kinase 1 promotes gastric cancer progression by regulating the tumor growth factor-beta signaling pathway.

The role of Tousled-like kinase 1 (TLK1) in in gastric cancer (GC) remains unclear. To investigate the expression, biological function, and underlying mechanisms of TLK1 in GC. We measured TLK1 protein expression levels and localized TLK1 in GC cells and tissues by western blot and immunofluorescence, respectively. We transfected various GC cells with lentiviruses to create TLK1 overexpression and knockdown lines and established the functional roles of TLK1 through in vitro colony formation, 5-ethynyl-2`-deoxyuridine, and Transwell assays as well as flow cytometry. We applied bioinformatics to elucidate the signaling pathways associated with TLK1. We performed in vivo validation of TLK1 functions by inducing subcutaneous xenograft tumors in nude mice. TLK1 was significantly upregulated in GC cells and tissues compared to their normal counterparts and was localized mainly to the nucleus. TLK1 knockdown significantly decreased colony formation, proliferation, invasion, and migration but increased apoptosis in GC cells. TLK1 overexpression had the opposite effects. Bioinformatics revealed, and subsequent experiments verified, that the tumor growth factor-beta signaling pathway was implicated in TLK1-mediated GC progression. The in vivo assays confirmed that TLK1 promotes tumorigenesis in GC. The findings of the present study indicated that TLK1 plays a crucial role in GC progression and is, therefore, promising as a therapeutic target against this disease.

Aberrant Activity of the Calcium Sensor STIM1 Underlies Congenital Platelet Disorders and Myeloproliferative Neoplasms

MB and VA equal contributors AB and STO co-corresponding authors This study was initiated following evaluation of a 32 year-old woman who presented with a history of thrombocytopenia identified in childhood who subsequently developed features of myelofibrosis (MF). A bone marrow biopsy demonstrated hypercellularity in conjunction with megakaryocyte hyperplasia and marked reticulin fibrosis. Molecular testing for JAK2, CALR, and MPL mutations was negative. Given the unusual association between congenital thrombocytopenia and MF in this patient, exome sequencing was performed, revealing a heterozygous R304W mutation in the coiled coil (CC) domain of STIM1. Activating mutations in the CC and EF hand domains of STIM1 have been associated with Stormorken syndrome, a rare congenital platelet disorder associated with abnormal store operated calcium entry (SOCE). We subsequently identified a second patient with MF associated with a STIM1 activating mutation. This individual was found to have severe thrombocytopenia at birth, and exome sequencing revealed a heterozygous S88G mutation in the EF hand of STIM1. A bone marrow biopsy obtained at 6 months of age revealed atypical megakaryocytes and grade 1-2 MF. A repeat biopsy at age 2 showed persistence of stable MF. The unusual finding of MF in these two patients suggested the possibility of altered calcium signaling as a shared mechanism driving congenital platelet disorders such as Stormorken syndrome and myeloproliferative neoplasms (MPNs) including MF. In support of this notion, we identified elevated STIM1 expression in MF vs normal megakaryocyte progenitors, as well as in platelets from patients with essential thrombocythemia (ET) vs healthy controls. Additionally, we found that STIM1 expression was significantly elevated in CD34+ hematopoietic stem/progenitor cells (HSPCs) from both ET and MF patients vs healthy controls. Notably, STIM1 expression was increased in both JAK2 and CALR-mutant MF patients. Collectively, these findings provide evidence of aberrant STIM1 expression in MPN patient cells. To determine the functional role of STIM1 in MPN disease development, colony assays and patient-derived xenograft (PDX) experiments were performed with MF patient CD34+ cells subjected to CRISPR ablation of STIM1. Strikingly discordant results were observed with JAK2 vs CALR-mutant patient samples. Abrogation of STIM1 in CALR-mutant CD34+ cells led to decreased colony formation, and NSGS mice engrafted in parallel with STIM1-targeted cells exhibited decreased human CD45+ cell engraftment in conjunction with prolonged survival. These findings suggest an important role for STIM1 in CALR-mutant MPN disease phenotypes. In contrast, targeting of STIM1 in JAK2-mutant CD34+ cells led to increased colony formation and exacerbated disease phenotypes in vivo as manifested by enhanced human CD45+ cell engraftment, worsened splenomegaly, and early lethality. Similar results were obtained in experiments utilizing pharmacologic inhibitors of SOCE activity. Taken together, these findings indicate that the consequences of aberrant STIM1 activity may be context-dependent relating to specific MPN driver mutations. To expand these observations, we identified a separate cohort of 9 family members in Italy with Stormorken syndrome and confirmed STIM1 EF hand mutations. In ex vivo megakaryocytic differentiation assays, cells from affected individuals exhibited a defect in proplatelet formation. These observations were corroborated by initial analyses of a newly generated Stim1 R304W conditional knock-in mouse which recapitulated the characteristic thrombocytopenia found in patients with Stormorken syndrome. In summary, this study represents the first demonstration of MF development in patients with Stormorken syndrome, thereby uncovering a previously unrecognized hallmark of altered calcium signaling via aberrant STIM1 activation underlying Stormorken syndrome and MPNs. Our findings suggest distinct mechanisms relating to the interaction between JAK2 vs CALR mutation and altered STIM1 activity. Further studies of these relationships may have important ramifications for potential therapeutic approaches targeting these pathways.

The ATR inhibitor berzosertib acts as a radio- and chemosensitizer in head and neck squamous cell carcinoma cell lines

Alterations in the DNA damage response play a crucial role in radio- and chemoresistance of neoplastic cells. Activation of the Ataxia telangiectasia and Rad3-related (ATR) pathway is an important DNA damage response mechanism in head and neck squamous cell carcinoma (HNSCC). Berzosertib, a selective ATR inhibitor, shows promising radio- and chemosensitizing effects in preclinical studies and is well tolerated in clinical studies. The aim of this study was to elucidate the effect of berzosertib treatment in combination with radiation and cisplatin in HNSCC. The HNSCC cell lines Cal-27 and FaDu were treated with berzosertib alone and in combination with radiation or cisplatin. Cell viability and clonogenic survival were evaluated. The effect of combination treatment was evaluated with the SynergyFinder or combination index. Apoptosis was assessed via measurement of caspase 3/7 activation and migration was evaluated using a wound healing assay. Berzosertib treatment decreased cell viability in a dose-dependent manner and increased apoptosis. The IC50 of berzosertib treatment after 72 h was 0.25–0.29 µM. Combination with irradiation treatment led to a synergistic increase in radiosensitivity and a synergistic or additive decrease in colony formation. The combination of berzosertib and cisplatin decreased cell viability in a synergistic manner. Additionally, berzosertib inhibited migration at high doses. Berzosertib displays a cytotoxic effect in HNSCC at clinically relevant doses. Further evaluation of combination treatment with irradiation and cisplatin is strongly recommended in HNSCC patients as it may hold the potential to overcome treatment resistance, reduce treatment doses and thus mitigate adverse events.

Enhanced synergy of pacritinib with temsirolimus and sunitinib in preclinical renal cell carcinoma model by targeting JAK2/STAT pathway

Pacritinib is an oral medication that inhibits several kinases including JAK2, FLT3, IRAK and STAT3. It has been recently approved to treat patients with thrombocytopenia and myelofibrosis. Studies are currently exploring the potential use of pacritinib in treating other types of cancer such as leukaemia, breast cancer and prostate cancer. Our study aimed to investigate the effects of pacritinib alone and its combination with standard of care in renal cell carcinoma (RCC). We showed that pacritinib dose-dependently decreased viability of RCC cells, with IC50 at nanomolar or low micromolar concentration rage. Pacritinib inhibited cell proliferation, decreased colony formation, and increased apoptosis. Interestingly, pacritinib exhibited synergistic effects when combined with temsirolimus and sunitinib, but antagonistic effects when combined with doxorubicin, in a panel of RCC cell lines. We also confirmed that the combination of pacritinib with temsirolimus and sunitinib resulted in synergistic effects in RCC mouse models, with complete inhibition of tumour growth throughout the treatment period. Mechanistic studies indicated that the inhibition of JAK2, but not IRAK, was the main contributor to the anti-RCC activity of pacritinib. Our study is the first to demonstrate that pacritinib shows promise as a treatment option for RCC and underscores the therapeutic potential of targeting the JAK2/STAT signalling pathway in RCC.

Death-associated protein kinase 1 phosphorylates MDM2 and inhibits its protein stability and function.

Breast cancer is one of the major malignancies in women, and most related deaths are due to recurrence, drug resistance, and metastasis. The expression of the mouse double minute 2 (MDM2) oncogene is upregulated in breast cancer; however, its regulatory mechanism has yet to be fully elucidated. Herein, we identified the tumor suppressor death-associated protein kinase 1 (DAPK1) as a novel MDM2 regulator by unbiased peptide library screening. DAPK1 is directly bound to MDM2 and phosphorylates it at Thr419. DAPK1-mediated MDM2 phosphorylation promoted its protein degradation via the ubiquitin-proteasome pathway, resulting in upregulated p53 expression. DAPK1 overexpression, but not its kinase activity-deficient form, decreased colony formation and increased doxorubicin-induced cell death; however, DAPK1 knockdown produced the opposite effects in human breast cancer cells. In a xenograft tumorigenesis assay, DAPK1 overexpression significantly reduced tumor formation, whereas inhibition of DAPK1 kinase activity reduced its antitumorigenic effect. Finally, DAPK1 expression was negatively correlated with MDM2 levels in human breast cancer tissues. Thus, these results suggest that DAPK1-mediated MDM2 phosphorylation and its protein degradation may contribute to its antitumorigenic function in breast cancer.

New JAK3-INSL3 Fusion Transcript-An Oncogenic Event in Cutaneous T-Cell Lymphoma.

Constitutively activated tyrosine kinase JAK3 is implicated in the pathogenesis of cutaneous T-cell lymphomas (CTCL). The mechanisms of constitutive JAK3 activation are unknown although a JAK3 mutation was reported in a small portion of CTCL patients. In this study, we assessed the oncogenic roles of a newly identified JAK3-INSL3 fusion transcript in CTCL. Total RNA from malignant T-cells in 33 patients with Sézary syndrome (SS), a leukemic form of CTCL, was examined for the new JAK3-INSL3 fusion transcript by RT-PCR followed by Sanger sequencing. The expression levels were assessed by qPCR and correlated with patient survivals. Knockdown and/or knockout assays were conducted in two CTCL cell lines (MJ cells and HH cells) by RNA interference and/or CRISPR/Cas9 gene editing. SS patients expressed heterogeneous levels of a new JAK3-INSL3 fusion transcript. Patients with high-level expression of JAK3-INSL3 showed poorer 5-year survival (n = 19, 42.1%) than patients with low-level expression (n = 14, 78.6%). CTCL cells transduced with specific shRNAs or sgRNAs had decreased new JAK3-INSL3 fusion transcript expression, reduced cell proliferation, and decreased colony formation. In NSG xenograft mice, smaller tumor sizes were observed in MJ cells transduced with specific shRNAs than cells transduced with controls. Our results suggest that the newly identified JAK3-INSL3 fusion transcript confers an oncogenic event in CTCL.

Disulfiram-Loaded Niosomes Reduces Cancerous Phenotypes in Oral Squamous Cell Carcinoma Cells.

Surgery and chemotherapy are the most common therapeutic strategies proposed for oral squamous cell carcinoma (OSCC). However, some of the disadvantages associated with the current methods like unwanted side effects and poor drug response lead the scientist to seek for novel modalities and delivery approaches to enhance the efficacy of treatments. The study aimed to assess the effectiveness of disulfiram (DSF)-loaded Niosomes on cancerous phenotypes of the OSCC cells. In this experimental study, an optimum formulation of DSF-loaded Niosomes was developed for the treatment of OSCC cells to reduce drug doses and improve the poor stability of DSF in the OSCC environment. The design expert software was utilized to optimize the particles in terms of size, polydispersity index (PDI), and entrapment efficacy (EE). Acidic pH increased the release rate of DSF from these formulations. The size, PDI, and EE of Niosomes were more stable at 4°C compared to 25°C. The results indicated that DSF-loaded Niosomes could induce apoptosis (P=0.019) in the OSCC cells compared to the control group. Moreover, it could reduce colony formation ability (P=0.0046) and also migration capacity of OSCC cells (P=0.0015). Our findings indicated that the application of proper dose of DSF-loaded Niosomes (12.5 μg/ml) increases apoptosis, decreases colony formation capacity and declines the migration ability of OSCC cells.

Similar deamination activities but different phenotypic outcomes induced by APOBEC3 enzymes in breast epithelial cells.

APOBEC3 (A3) enzymes deaminate cytosine to uracil in viral single-stranded DNA as a mutagenic barrier for some viruses. A3-induced deaminations can also occur in human genomes resulting in an endogenous source of somatic mutations in multiple cancers. However, the roles of each A3 are unclear since few studies have assessed these enzymes in parallel. Thus, we developed stable cell lines expressing A3A, A3B, or A3H Hap I using non-tumorigenic MCF10A and tumorigenic MCF7 breast epithelial cells to assess their mutagenic potential and cancer phenotypes in breast cells. The activity of these enzymes was characterized by γH2AX foci formation and in vitro deamination. Cell migration and soft agar colony formation assays assessed cellular transformation potential. We found that all three A3 enzymes had similar γH2AX foci formation, despite different deamination activities in vitro. Notably, in nuclear lysates, the in vitro deaminase activity of A3A, A3B, and A3H did not require digestion of cellular RNA, in contrast to that of A3B and A3H in whole-cell lysates. Their similar activities in cells, nonetheless, resulted in distinct phenotypes where A3A decreased colony formation in soft agar, A3B decreased colony formation in soft agar after hydroxyurea treatment, and A3H Hap I promoted cell migration. Overall, we show that in vitro deamination data do not always reflect cell DNA damage, all three A3s induce DNA damage, and the impact of each is different.

Inhibition of BPHL inhibits proliferation in lung carcinoma cell lines.

Lung cancer is one of the most common human malignant tumors and the leading cause of cancer death worldwide. Biphenyl hydrolase-like (BPHL) is a gene encoding the human BPHL enzyme, a serine hydrolase that catalyzes the hydrolytic activation of amino acid ester prodrugs of nucleoside analogs such as valacyclovir and valganciclovir. However, the role of BPHL in lung cancer is still unknown. In this study, we assessed the effect BPHL knockdown on the proliferation, apoptosis, colony formation, metastasis, and cell cycle of cancer cells. BPHL knockdown NCI-H1299 and A549 cells demonstrated decreased proliferation, as measured by Celigo cell counting. The MTT assay results were consistent with Celigo cell counting. Caspase 3/7 activity increased significantly in the NCI-H1299 and A549 cells after shBPHL knockdown. Decreased colony formation in the NCI-H1299 and A54 cells after shBPHL knockdown, as measured by crystal violet staining. Transmigration assay using a Transwell demonstrated that there were significantly fewer migrating cells in the lower chamber in the BPHL knockdown NCI-H1299 and A549 cells. Cell cycle analysis by Propidium Iodide (PI) staining and fluorescence activated cell sorter (FACS). We also explored the effect of BPHL knockdown on tumor growth in a mouse model of tumor implantation in nude mice. We found that the knockdown of BPHL gene expression by short hairpin RNA (shRNA) leads to a decrease in proliferation, colony formation, and metastasis and an increase in apoptosis in two lung adenocarcinoma (LUAD) cell lines in vitro. BPHL knockdown induces decreased tumor growth, colony formation, and metastasis; increased apoptosis; and altered cell cycle destruction. BPHL knockdown results in decreased tumor growth in vivo. Moreover, BPHL knockdown A549 cells demonstrated slower growth compared to control cells upon implantation in nude mice, confirming the in vitro findings. In this study, the data indicate that BPHL potentially promotes proliferation, inhibits apoptosis, and increases colony formation and metastasis in lung cancer. Overall, our study suggests that BPHL may be a gene that promotes tumor growth in lung cancer.

Zinc finger transcription factor CASZ1b is involved in the DNA damage response in live cells

Zinc finger transcription factor CASZ1b is essential for nervous system development and suppresses neuroblastoma growth. Our previous study showed that CASZ1b interacts with DNA repair proteins, however, whether CASZ1b is involved in the DNA damage response remains unclear. In this study, we investigated the kinetic recruitment of CASZ1b to sites of DNA damage upon induction by laser microirradiation. We find that CASZ1b is transiently recruited to sites of DNA damage in multiple cell lines. Mutagenesis of either the poly-(ADP-ribose) (PAR) binding motif or NuRD complex binding region in CASZ1b significantly reduces the recruitment of CASZ1b to these sites of DNA damage (∼65% and ∼30%, respectively). In addition, treatment of cells with a poly-(ADP-ribose) polymerase (PARP) inhibitor significantly attenuates the recruitment of CASZ1b to these DNA damaged sites. Loss of CASZ1 increases cell sensitivity to DNA damage induced by gamma irradiation as shown by decreased colony formation. Our studies reveal that CASZ1b is transiently recruited to DNA damage sites mainly in a PARP-dependent way and regulates cell sensitivity to DNA damage. Our results suggest that CASZ1b has a role, although perhaps a minor one, in the DNA damage response and ultimately regulating the efficiency of DNA repair during normal development and tumorigenesis.

Abstract 289: B7-H3 mediated metabolic reprogramming promotes small cell lung cancer progression

Abstract Lung cancer is the leading cause of cancer-related deaths worldwide. Small cell lung cancer (SCLC) is an aggressive subtype of lung cancer. The overall survival rate of SCLC is dismal owing to early metastasis, chemoresistance, higher rate of recurrence, and lack of available treatment options. Although some immunotherapeutic drugs have been approved for SCLC, they are effective only in a small fraction of the patient population. This necessitates the quest to find promising vulnerabilities against SCLC. Bioinformatic analysis on SCLC data set in the backdrop of various immune checkpoint regulators revealed B7-H3 as a promising target. The bioinformatics data was recapitulated in SCLC cell lines and human SCLC tissues. To delineate the effects of B7-H3 targeting, we performed CRISPR-Cas9 mediated B7-H3 knockout in SCLC cell lines. B7-H3 knockout in SCLC cells showed a decrease in colony formation, migration, and wound healing properties. Our results suggest that deletion of B7-H3 decrease the functional activities and activation of oncogenic signaling pathways, such as Erk, Akt, and Stat3. Further, we assessed if B7-H3 regulates SCLC metabolism. Preliminary data showed that B7-H3 knockout in SCLC cells inhibits glucose uptake, extracellular acidification rate (ECAR), and oxygen consumption rate (OCR), suggesting its role in SCLC metabolic reprogramming. Altogether, our data indicate that B7-H3 plays a crucial role in SCLC pathogenesis and could serve as a potential therapeutic target for SCLC. Citation Format: Mahek Fatima, Parvez Khan, Asad Ur Rehman, Md Arafat Khan, Shailendra Kumar Maurya, Aatiya Ahmad, Mohd Ali Zaidi, Shailendra Gautam, Subodh Lele, Surinder Kumar Batra, Mohd Wasim Nasser. B7-H3 mediated metabolic reprogramming promotes small cell lung cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 289.

Abstract 1003: The prognostic significance of prolyl 4-hydroxylase subunit alpha 1 and the therapeutic efficacy of diethyl-pythiDC, its small molecule inhibitor, in pancreatic ductal adenocarcinoma

Abstract Background: Prolyl 4-hydroxylase subunit alpha 1 (P4HA1) has an oncogenic role in pancreatic ductal adenocarcinoma (PDAC). Since high expression of P4HA1 in PDAC is suggested to correlate with poor prognosis, targeting P4HA1 could have therapeutic benefits. Herein, we assessed the prognostic significance of P4HA1 expression at the RNA and protein levels in PDAC using publicly available data. We also evaluated the efficacy of diethyl-pythiDC, a small molecule inhibitor of P4HA1, in PDAC cells. Methods: UALCAN (ualcan.path.uab.edu), a comprehensive proteogenomic cancer data analysis portal, was used to obtain gene expression P4HA1 as transcripts per million reads (TPM) (PDAC n=178) from The Cancer Genome Atlas (TCGA); levels of P4HA1 protein expression data were obtained from (normal pancreas, n=74, PDAC n=137) the Clinical Proteomic Tumor Analysis consortium (CPTAC). Immunohistochemical analysis obtained from Human Protein Atlas (HPA) confirmed increased P4HA1 protein expression. Overall survival (OS) between patients with high and low/medium TPM (TPM values above and below upper quartile, respectively) and high and low protein expression score (based on staining intensity and fraction of stained cells) was calculated using the log-rank Wilcoxon test. To determine the efficacy of diethyl-pythiDC in PDAC cells (PANC-1 and BxPC-3), we performed clonogenic assay for colony formation, MTT assay for cell proliferation, flow cytometry for cell cycle analysis, and western blotting for markers of the epithelial-mesenchymal transition (EMT). Results: In the TCGA data, high P4HA1 expression (TPMs) was associated with a poor prognosis (high expression vs. low/medium expression, log-rank p=0.009). Analysis of HPA data showed that the 5-year OS of patients with high P4HA1 expression was 12% vs. 58% for patients with low P4HA1 (log-rank p<0.001). CPTAC data showed higher P4HA1 protein expression in patients with receptor tyrosine kinase (RTK) pathway (p<0.001), mammalian target of rapamycin (mTOR) pathway (p=0.045) and SWItch/Sucrose Non-Fermentable (SWI-SNF) complex (p=0.022) alterations. Diethyl-pythiDC treatment of PDAC cells reduced proliferation, decreased colony formation, and increased G2/M cell cycle arrest. In addition, diethyl-pythiDC increased protein expression of E-cadherin, an epithelial marker, and decreased the expression of N-cadherin and vimentin, the mesenchymal protein markers. Conclusions: Patients with high P4HA1 expression had poor OS. CPTAC data showed higher P4HA1 protein expression in patients with RTK, mTOR and SWI-SNF alterations. Targeting P4HA1 with diethyl-pythiDC reduced proliferation by arresting cells in G2/M phase of the cell cycle and modulated EMT markers. Thus, targeting of P4HA1 can be a viable strategy and may be considered in future PDAC clinical trials. Citation Format: Moh'd Khushman, Farrukh Afaq, Prachi Bajpai, Sameer Al Diffalha, Darryl Outlaw, Grant R. Williams, Rojymon Jacob, Kondal Rao Kyanam Kabir, Ali Ahmed, Peter Shajan, Sooryanarayana Varambally, Upender Manne. The prognostic significance of prolyl 4-hydroxylase subunit alpha 1 and the therapeutic efficacy of diethyl-pythiDC, its small molecule inhibitor, in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1003.

Abstract 419: Elevated Akt/mTOR signaling drives therapy resistance in ALM

Abstract Metastatic acral lentiginous melanoma (ALM) is the most lethal subtype of cutaneous melanoma and effective therapies for patients have not been established. Studies revealed a link between the dysregulation of CDK4/6 and ALM mortality, however CDK4/6 inhibitors (CDK4i/6i) have proved ineffective in patients with advanced ALM. The tumor suppressor Rb was recently shown to have a novel suppressive role towards mTORC2. Here, we elucidate the role of a non-canonical tumor suppressor function of Rb in negative regulation of mTOR in CDK4i/6i-resistance. We hypothesize that the loss of Rb induced by CDK4i/6i triggers phosphorylation of Akt and downstream mTORC1 signaling pathways. We characterized baseline activity of the PI3K/AKT/mTOR pathway in a panel of ALM cell lines, finding heterogeneity across signaling. We immunoblotted for key proteins involved in the signal reprogramming hypothesized: pRb, pAkt, pS6 to define activation status and found the loss of Rb phosphorylation preceded the enrichment of pAKT, supporting the non-canonical role of Rb tumor suppression and the Rb-mTORC2 signaling axis as intrinsic CDK4i/6i mechanism. In parallel, we assessed the essential protein-protein interactions required for mechanistic mTORC1 activation—mTOR and Rheb GTPase. The enrichment of these interactions shortly after introducing CDK4i/6i supported our hypothesized mechanism. Translational utility of CDK4i/6i and mTORi dual inhibition was determined via long-term Colony Formation Assays (CFAs) using Palbociclib, rapamycin and sapanisertib (TAK228), a catalytic mTOR inhibitor. We generated Palbociclib (acquired)-resistant ALM cell lines and investigated the pharmacological inhibition of PI3K signaling pathways through immunoblot and colony-formation assays. Concurrent mTORi and CDK4i/6i inhibition showed effective reduction in pRb, pS6, Cyclin D and increases in Cleaved PARP protein, suggesting apoptotic cell death was elevated with combined CDK4i/6i+mTORi treatment. Similarly, CFAs revealed dual inhibition elicited superior antiproliferative effect over the monotherapy treatments. CFAs with acquired-resistance cell lines also showed that combination inhibition decreased colony formation, showing the potential utility of concurrent CDK4i/6i and mTORi as an approach against acquired resistance. Our results show the efficacy of combined inhibition as an anti-tumor strategy. Citation Format: Jeremy A. Bravo Narula, Vito W. Rebecca. Elevated Akt/mTOR signaling drives therapy resistance in ALM [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 419.

4-Nerolidylcatechol (4-NC) and Docetaxel Synergize in Controlling Androgen- independent Prostate Cancer Cells.

Effective cancer treatment still challenges medicine since the strategies employed so far are not sufficiently safe and capable of specifically eliminating tumor cells. Prostate cancer (PCa) is a highly incident malignant neoplasm, and the outcome of patients, especially those with advanced castration-resistant PCa (CRPC), depends directly on the efficacy of the therapeutic agents, such as docetaxel (DOC). This study investigated the synergistic potentiation of 4-nerolidylcatechol (4-NC) with DOC in inhibiting androgen-independent PCa cells. The cytotoxic effect of 4-NC was evaluated against non-tumorigenic (RWPE-01) and PCa cell lines (LNCaP and PC-3), and the antiproliferative potential of 4-NC was assessed by flow cytometry and colony formation. The Chou-Talalay method was applied to detect the synergistic effect of 4-NC and DOC, and the mechanism of anticancer activities of this combination was investigated by analyzing players in epithelial-mesenchymal transition (EMT). 4-NC significantly reduced the viability of PC-3 cells in a dose-dependent manner, decreasing colony formation and proliferation. The combination of 4-NC and DOC was synergistic in the androgen-independent cells and allowed the reduction of DOC concentration, with increased cytotoxicity and induction of apoptosis when compared to compounds alone. Furthermore, when 4- NC was co-administered with DOC, higher expression levels of proteins associated with the epithelial phenotype were observed, controlling EMT in PC-3 cells. Collectively, these data demonstrated, for the first time, that the combination of 4-NC with reduced doses of DOC could be especially valuable in the suppression of oncogenic mechanisms of androgen-independent PCa cells.

Momordica cochinchinensis Suppresses the Human Breast Cancer Cells Growth and Migration by Inhibiting Mevalonate Pathway

Background: Momordica cochinchinensis (MC) is shown with high antioxidation and is used as herbal medicine in South-East countries. Objectives: This study aims to determine the four parts (aril, fruit, leaf, and seed) of MC extract against human breast cancer cells with underlying mechanisms of actions. Materials and Methods: The effects of MC extract were examined by sulforhodamine B, colony formation, wound healing, real time polymerase chain reaction (RT-PCR), and Western blotting method. Results: Four parts of MC extracts significantly increased MCF-7 cells death, interestingly, seed extract had the greatest activity with IC50 values of 412.3 ± 49.8 µg/mL for 24 h and 113.3 ± 6.4 µg/mL for 48 h. MC extracts potentiated the anticancer drug effect, doxorubicin, with lower IC50 values when compared with MC treatment alone. Moreover, MC extracts decreased colony formation and accompanied by inhibited cell migration. Furthermore, Seed extract inhibited migration by reducing matrix metalloproteinases (MMP) 2, MMP 9, and vascular endothelial growth factor A (VEGFA) inhibition. The molecular analyses revealed that seed extract inhibited cell viability by decreasing cyclin D1 consistent with activating p21, cytochrome c, and caspase-3 protein levels along with reduction of mevalonate (MVA) pathway, Rac1, and RhoA levels, it appeared to inhibit growth and migration. Conclusion: Taken together, MC extract induces MCF-7 cell death and decreases cell migration relatively via attenuation of MVA pathway.

Abstract P6-10-08: Evaluation of potent novel second-generation MELK-selective inhibitor in aggressive breast cancers

Abstract Background Inflammatory breast cancer (IBC) and triple-negative breast cancer (TNBC) are aggressive breast cancer subtypes with poor clinical outcomes due to the lack of well-validated and actionable targets and the onset of chemo-resistant metastasis. TNBC and IBC account for 15-20% and 2-4% of all breast cancer diagnoses but result in 30% and 8%–10% of breast cancer-related deaths, respectively. MELK (maternal embryonic leucine zipper kinase) is a potential therapeutic target in both TNBC and triple-negative IBC (TN-IBC). We have shown that 1) MELK expression is higher in basal tumors (mostly TNBC) and in IBC than in non-IBC, 2) high MELK expression is an independent prognostic factor for poor overall survival (P=0.0002) and poor distant metastasis-free survival (P=0.008) in breast cancer, and 3) MELK knockout leads to significantly lower metastatic burden and prolonged survival in a xenograft model of TNBC (unpublished data). MELK inhibitor (MELKi) OTS167 is in clinical trials but it lacks specificity and cross-reacts with other essential kinases. It is critical to discover novel, selective inhibitors with good bioavailability that target MELK and minimize adverse effects. We have developed a second-generation small-molecule MELK inhibitor 30e that is a highly potent and slow-binding ATP-competitive inhibitor of MELK. 30e exhibits potent cellular inhibition of MELK (IC50< 10 nM), as assessed using a live cell NanoBRET assay, and is highly selective as assessed by live-cell KiNativ profiling experiments in MDA-MB-231 TNBC cells. Methods We screened a panel of TNBC and IBC cell lines for MELK expression by western blot and qPCR analysis. We assessed the effects of MELK inhibition with the 30e on migration and invasion. The role of MELK in regulating cancer stem cell phenotypes was assessed using the mammosphere assay and flow cytometry (CD44+/CD24-/low surface marker). MELK’s protumorigenic role was determined in vitro using a soft agar assay, and the anti-tumor activity of 30e was assessed in vivo using a TN-IBC orthotopic xenograft mouse model. Results We found that TNBC had high mRNA levels of MELK (62%) compared to non-TNBC cell lines (25%), which correlated with MELK protein levels. 30e inhibited cell viability in TNBC and IBC cells in a dose-dependent manner and with IC50s ranging from 0.45 to 1.76 μM (P≤0.05). However, no significant effect was observed when normal MCF-10A breast cells were treated with 30e (IC50>20 μM). 30e also significantly reduced colony formation ability. Further, we observed that 30e reduced mammosphere formation efficiency and the CD44+/CD24-/low subpopulation in both TNBC and IBC cells in a dose-dependent manner (P≤0.05), suggesting the potential of 30e to inhibit the stem cell population in vitro. The soft agar assay also showed a significant decrease in colony formation in the TNBC and IBC cells after treatment with 30e, an indirect indicator of in vivo tumorigenicity. To assess the efficacy of 30e treatment on tumor growth, we evaluated this inhibitor as a single agent in a SUM-149 (TN-IBC) orthotopic mouse model. The mice were treated with intraperitoneal injections daily with 3 doses (2.5, 5, and 10 mg/kg) of 30e. Our data show that 30e suppressed tumor growth in a dose-dependent manner (P< 0.007). Conclusions and Future Directions Our data demonstrate that a novel, potent and specific MELK inhibitor inhibits tumor growth by suppressing the cancer stem cell phenotype. MELK is a promising target for aggressive cancers such as TNBC and IBC. We are evaluating how MELK inhibition modulates the tumor microenvironment, which is a critical component of breast cancer response to treatment. We performed a cytokine antibody array and are validating the top targets. Further, we will evaluate 30e in combination with standard-of-care treatment for toxicity and inhibition of metastasis. Citation Format: Mohd Mughees, Moises Tacam, Alex Tan, Hector Gonzalez, Emilly S. Villodre, Bisrat Debeb, Debu Tripathy, Geoffrey Bartholomeusz, Juhyeon Lee, Kevin Dalby, Chandra Bartholomeusz. Evaluation of potent novel second-generation MELK-selective inhibitor in aggressive breast cancers [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-10-08.

Targeting leukemic stem cell subpopulation in AML using phytochemicals: An in-silico and in-vitro approach

It has been indicated that leukemic stem cells (LSCs), a subset of leukaemia cells, are responsible for therapy resistance and relapse in acute myeloid leukaemia (AML). Therefore, the current study aimed to discover an LSC biomarker in AML patients and identify a natural compound that may target the same. By performing the different gene expression analyses, we identified 12 up-regulated and 192 down-regulated genes in LSCs of AML compared to normal bone marrow-derived HSCs. Further STRING interaction, GO enrichment and KEGG pathway analysis were carried out to top hub genes. Wilms’ tumour-1 (WT1) transcription factor was pointed out as the top hub gene and a potential biomarker for LSCs in AML. For the targeted inhibition of WT1, we performed screening and stimulation of potential natural compounds. The results revealed Gallic acid (GA) and Chlorogenic acid (CA) as promising WT1 inhibitors. In-vitro validation of cytotoxic effects of both GA and CA on THP-1 and HL-60 cell lines suggested that both these compounds inhibited cell proliferation. Still, GA has a more cytotoxic effect compared to CA. Next, we performed cell cycle analysis and apoptosis analysis and found that both compounds arrested cells in G0/G1 phase and induced apoptosis in both cell lines. Surprisingly, a significant decrease in colony formation and cell migration was also observed. However, GA gave more promising results in all cellular assays than CA. Furthermore, we studied the mRNA expression of WT1 and BCL2, which are transcriptionally activated by it. We found that GA significantly downregulated both these genes compared to CA. Our results suggested that GA is a potential inhibitor of WT1 and might be an excellent anti-LSCs natural drug for AML patients.

Depletion of SOD2 enhances nasopharyngeal carcinoma cell radiosensitivity via ferroptosis induction modulated by DHODH inhibition

BackgroundRecurrence due to the development of radioresistance remains a major challenge in the clinical management of nasopharyngeal carcinoma. The objective of this study was to increase the sensitivity of nasopharyngeal carcinoma cells to ionizing radiation by enhancing oxidative stress and ferroptosis caused by disrupting the mitochondrial anti-oxidant enzyme system.MethodsOxidative stress cell model was constructed by SOD2 knockdown using shRNA. The expression and activity of DHODH was suppressed by siRNA and brequinar in SOD2 depleted cells. Protein levels were determined by western blotting and ferroptosis was assessed by C11 BODIPY and malondialdehyde assay. Cell viability was evaluated using CCK-8 assay while radiotoxicity was assessed by colony formation assay. Cellular ATP level was determined by ATP assay kits, ROS was determined by DCFD and DHE, while mitochondrial oxygen consumption was determined by seahorse assay. Data were analyzed by two-tailed independent t-test.ResultsRadiation upregulated SOD2 expression and SOD2 depletion increased cellular O2.−, malondialdehyde, and the fluorescence intensity of oxidized C11 BODIPY. It also resulted in mitochondrial damage. Its depletion decreased colony formation both under ionizing and non-ionizing radiation conditions. The ferroptosis inhibitor, deferoxamine, rescued cell viability and colony formation in SOD2 depleted cells. Cellular level of malondialdehyde, fluorescence intensity of oxidized C11 BODIPY, O2.− level, ATP, and mitochondrial oxygen consumption decreased following DHODH inhibition in SOD2 depleted cells. Cell viability and colony formation was rescued by DHODH inhibition in SOD2 depleted cells.ConclusionInducing oxidative stress by SOD2 inhibition sensitized nasopharyngeal carcinoma cells to ionizing radiation via ferroptosis induction. This was found to be dependent on DHODH activity. This suggests that DHODH inhibitors should be used with caution during radiotherapy in nasopharyngeal carcinoma patients.