Manganese(III)-salens induce tumor selective apoptosis in human cells

Investigating of the anticancer activity of salen/salophen metal complexes based on graphene quantum dots: Induction of apoptosis as part of biological activity

This research work is the first report on the synthesis and stabilization of [Fe-Salophen] and [Fe-Salen] complexes by two methods of surface modification and anchoring of synthesized Schiff base ligand on the surface of graphene quantum dots (GQDs). The GQDs contain oxygenated functional groups that can act as non-radiative electron-hole recombination centers. Therefore removing these oxygen functional groups may improve quantum yield by reducing or deactivating the surface. In this work, GQDs with the amine functional group were synthesized with a quantum yield of 37.48%. The physicochemical properties of GQDs were investigated by Ultraviolet-visible (UV-Vis) and fluorescence spectroscopies, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Powder X-ray diffraction (PXRD), Transmission electron microscope (TEM). The synthesis of GQDs-[Fe-Salen] and GQDs-[Fe-Salophen] was evaluated by FT-IR, Inductively coupled plasma atomic emission spectroscopy (ICP-AES) and Energy dispersive X-Ray analysis (EDX) analyses. Then, using MTT- assay, annexin V-FITC/PI, DAPI staining and cellular uptake assays, the biochemical activity of these complexes on the MCF7 cell line was investigated. The results shows that GQDs-[Fe-Salen] and GQDs-[Fe-Salophen] affect the survival of MCF7 cancer cells and, by nuclear fragmentation cause 35.77% and 19.41% of early apoptosis in cells, respectively. Also was found cellular uptake of GQDs-[Fe-Salen] is higher than that of GQDs-[Fe-Salophen].

Syntheses, Structural Characterization, and Cytotoxicity Assessment of Novel Mn(II) and Zn(II) Complexes of Aroyl-Hydrazone Schiff Base Ligand

This work describes the syntheses, structural characterization, and biological profile of Mn(II)- and Zn(II)-based complexes 1 and 2 derived from the aroyl-hydrazone Schiff base ligand (L1). The synthesized compounds were thoroughly characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), UV-vis, electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and single-crystal X-ray diffraction (s-XRD). Density functional theory (DFT) studies of complexes 1 and 2 were performed to ascertain the structural and electronic properties. Hirshfeld surface analysis was used to investigate different intermolecular interactions that define the stability of crystal lattice structures. To ascertain the therapeutic potential of complexes 1 and 2, in vitro interaction studies were carried out with ct-DNA and bovine serum albumin (BSA) using analytical and multispectroscopic techniques, and the results showed more avid binding of complex 2 than complex 1 and L1. The antioxidant potential of complexes 1 and 2 was examined against the 2,2-diphenyl picrylhydrazyl (DPPH) free radical, which revealed better antioxidant ability of the Mn(II) complex. Moreover, the antibacterial activity of synthesized complexes 1 and 2 was tested against Gram-positive and Gram-negative bacteria in which complex 2 demonstrated more effective bactericidal activity than L1 and complex 1 toward Gram-positive bacteria. Furthermore, the in vitro cytotoxicity assessment of L1 and complexes 1 and 2 was carried out against MDA-MB-231 (triple negative breast cancer) and A549 (lung) cancer cell lines. The cytotoxic results revealed that the polymeric Zn(II) complex exhibited better and selective cytotoxicity against the A549 cancer cell line as was evidenced by its low IC₅₀ value.

Synthesis of Mn-ofloxacin complex, experimental and in silico DNA binding evaluation, biological activity assessment

Metal-fluoroquinolones have more antibacterial and cytotoxic effects compared to free fluoroquinolones. In this work, a bidentated Mn (II) complex with ofloxacin (MOC) was synthesized and its cytotoxicity activity, oxidative stress and DNA binding were studied. Anti- proliferative and cytotoxic tests revealed that MOC exhibits better anti proliferative and cytotoxic activities compared to OFL which was attributed to the more interaction of MOC with DNA. Therefore, the interaction of MOC with DNA was investigated by using voltammetry, UV-Vis, fluorescence, and in silico methods. The results revealed that MOC interacts with DNA via electrostatic and outside hydrogen binding via minor groove. The proposed DNA binding modes may support the greater in-vitro cytotoxicity of MOC compared to OFL alone.

Taming salophen in rare earth metallocene chemistry

An unprecedented series of salophen-bridged rare earth metallocenes, (Cp*2RE)2(μ-tBusalophen) (RE = Gd, Dy, and Y), has been crystallized. The solid and solution states have been unambiguously characterized by magnetic, spectroscopic and DFT methods.

A reactive oxygen species-generating, cancer stem cell-potent manganese(ii) complex and its encapsulation into polymeric nanoparticles

Intracellular redox modulation offers a viable approach to effectively remove cancer stem cells (CSCs), a subpopulation of tumour cells thought to be responsible for cancer recurrence and metastasis. Here we report the breast CSC potency of reactive oxygen species (ROS)-generating manganese(ii)- and copper(ii)-4,7-diphenyl-1,10-phenanthroline complexes bearing diclofenac, a nonsteriodial anti-inflammatory drug (NSAID), 1 and 3. Notably, the manganese(ii) complex, 1, exhibits 9-fold, 31-fold, and 40-fold greater potency towards breast CSCs than 3, salinomycin (an established breast CSC-potent agent), and cisplatin (a clinically approved anticancer drug) respectively. Encouragingly, 1 displays 61-fold higher potency toward breast CSCs than normal skin fibroblast cells. Clinically relevant epithelial spheroid studies show that 1 is able to selectively inhibit breast CSC-enriched HMLER-shEcad mammosphere formation and viability (one order of magnitude) over non-tumorigenic breast MCF10A spheroids. Mechanistic studies show that 1 prompts breast CSC death by generating intracellular ROS and inhibiting cyclooxygenase-2 (COX-2) activity. The manganese(ii) complex, 1, induces a greater degree of intracellular ROS in CSCs than the corresponding copper(ii) complex, 3, highlighting the ROS-generating superiority of manganese(ii)- over copper(ii)-phenanthroline complexes. Encapsulation of 1 by biodegradable methoxy poly(ethylene glycol)-b-poly(d,l-lactic-co-glycolic) acid (PEG-PLGA) copolymers at the appropriate feed (5%, 1 NP5 ) enhances breast CSC uptake and greatly reduces overall toxicity. The nanoparticle formulation 1 NP5 indiscriminately kills breast CSCs and bulk breast cancer cells, and evokes a similar cellular response to the payload, 1. To the best of our knowledge, this is the first study to investigate the anti-CSC properties of managense complexes and to demonstrate that polymeric nanoparticles can be used to effectively deliver managense complexes into CSCs.

A family of manganese complexes containing heterocyclic-based ligands with cytotoxic properties

We describe the synthesis of three new manganese (II) complexes containing the bidentate ligands 2-(1-methyl-3-pyrazolyl)pyridine (pypz-Me) and ethyl 2-(3-(pyridine-2-yl)-1H-pyrazol-1-yl)acetate (pypz-CH₂COOEt), with formula [MnX₂(pypz-Me)₂] (X = Cl^-1, CF₃SO₃^-2) and [Mn(CF₃SO₃)₂(pypz-CH₂COOEt)₂] 3. Complexes 1-3 have been characterized through analytical, spectroscopic and electrochemical techniques, as well as by monocrystal X-ray diffraction analysis. The complexes show a six-coordinated Mn(II) ion though different stereoisomers have been isolated for the three compounds. Complexes 1-3, together with the previously described compounds [MnCl₂(pypz-H)₂] 4, [Mn(CF₃SO₃)₂(pypz-H)₂] 5, [Mn(NO₃)₂(pypz-H)₂] 6, [MnCl₂(H₂O)₂(pypz-H)₂] 7 (pypz-H = 2-(3-pyrazolyl)pyridine) and ([Mn(CF₃SO₃)₂((-)-L)₂] 8, ((-)-L = (-)-pinene[5,6]bipyridine), were tested in vitro for cytotoxic activity against NCI-H460 and OVCAR-8 cancer cell lines. The geometry of a specific compound does not seem to influence its activity in a significant extent. However, among the tested compounds those that display hydrophobic substituents on the pyrazole ring and triflate ions as labile ligands show the best antiproliferative properties. Specifically, compound 8 containing the pinene-bipyridine ligand presents an antiproliferative activity similar to that of cisplatin and higher than that of carboplatin, and displays selectivity for tumour cells. Its antiproliferative effect is due to the generation of ROS species that allow the compound to interact with DNA.

New Fe(iii) and Co(ii) salen complexes with pendant distamycins: selective targeting of cancer cells by DNA damage and mitochondrial pathways

Minor groove binding distamycin like moieties were conjugated with core salens and the corresponding Fe(iii) and Co(ii) complexes were synthesized. Herein, we have shown efficient DNA minor groove binding specificities along with excellent DNA cleavage capacities with metallosalen conjugates. The metal complexes showed toxicity toward various cancer cells over normal cells with high specificity. Interestingly, the Co(ii) complexes exhibited greater activity than the Fe(iii) complexes in accordance with the stronger affinity of the former in the biophysical studies. Active DNA damage, and prominent nuclear condensation along with the release of cytochrome-c from the mitochondria unanimously showed that the metal complexes followed apoptotic pathways to induce cell death.

Salen-Mn compounds induces cell apoptosis in human prostate cancer cells through promoting AMPK activity and cell autophagy

Currently only docetaxel has been approved to be used in the chemotherapy of prostate cancer and new drugs are urgent need. Salen-Mn is a novel type of synthetic reagent bionic and exerts remarkable anticancer activities. However, the effect of Salen-Mn on human prostate cancer has not been elucidated yet. In this study, we found that treatment of PC-3 and DU145 human prostate cancer cells with Salen-Mn inhibited cell growth in dose and time dependent manner. Moreover, Salen-Mn induced cell apoptosis, and increased the expression of apoptotic proteins, such as cleaved caspase-3, cleaved PARP, and Bax, in PC-3 and DU145 prostate cancer cells. Furthermore, we found that Salen-Mn induced expression of LC3-I/II, which is protein marker of cell autophagy, in both dose and time dependent manners; in addition, Salen-Mn increased the phosphorylation of AMPK, suggesting that Salen-Mn increase cell autophagy through activating AMPK pathway. On the other hand, when PC-3 and DU145 cells were treated with Salen-Mn and 3-MA, an inhibitor of cell autophagy, the inhibitory effect of Salen-Mn on cell growth and the induction of apoptotic proteins were decreased. In addition, we found that Salen-Mn inhibited the growth of PC-3 cell xenografts in nude mice. In summary, our results indicate that Salen-Mn suppresses cell growth through inducing AMPK activity and autophagic cell death related cell apoptosis in prostate cancer cells and suggest that Salen-Mn and its derivatives could be new options for the chemical therapeutics in the treatment of prostate cancer.

A novel β-diiminato manganeseIII complex as the promising anticancer agent induces G0/G1 cell cycle arrest and triggers apoptosis via mitochondrial-dependent pathways in MCF-7 and MDA-MB-231 human breast cancer cells

Novel β-diiminato manganese^III complex has shown promising anti-breast cancer activity.

A novel [Mn2(μ-(C6H5)2CHCOO)2(bipy)4](bipy)(ClO4)2 complex loaded solid lipid nanoparticles: synthesis, characterization and in vitro cytotoxicity on MCF-7 breast cancer cells

Manganese (Mn)-based complexes have been drawing attention due to the fact that they are more effective than other metal complexes. However, the use of Mn(II)-based complexes in medicine remains limited because of certain side effects. The aim of this study was to investigate the cytotoxic and apoptotic effects of a novel Mn(II) complex [Mn₂(μ-(C₆H₅)₂CHCOO)₂(bipy)₄](bipy)(ClO₄)₂ and Mn(II) complex loaded solid lipid nanoparticles (SLNs) on MCF-7 and HUVEC control cells. The average diameter of Mn(II) complex was about 1120 ± 2.43 nm, while the average particle size of Mn(II) complex-SLNs was ∼340 ± 2.27 nm. The cytotoxic effects of Mn(II) complex and Mn(II)-SLNs were 86.8 and 66.4%, respectively (p < .05). Additionally, both Mn(II) complex (39.25%) and Mn(II)-SLNs (38.05%) induced apoptosis and increased the arrest of G₀/G₁ phase. However, Mn(II) complex exerted toxic effects on the HUVEC control cell (63.4%), whereas no toxic effects was observed when treated with Mn(II)-SLNs at 150 μM. As a consequence, SLNs might be potentially used for metal-based complexes in the treatment of cancer due to reducing size and toxic effects of metal-based complexes.

Endocrine disrupting chemical, bisphenol-A, induces breast cancer associated gene HOXB9 expression in vitro and in vivo

HOXB9 is a homeobox-containing gene that plays a key role in mammary gland development and is associated with breast and other types of cancer. Here, we demonstrate that HOXB9 expression is transcriptionally regulated by estradiol (E2), in vitro and in vivo. We also demonstrate that the endocrine disrupting chemical bisphenol-A (BPA) induces HOXB9 expression in cultured human breast cancer cells (MCF7) as well as in vivo in the mammary glands of ovariectomized (OVX) rats. Luciferase assay showed that estrogen-response-elements (EREs) in the HOXB9 promoter are required for BPA-induced expression. Estrogen-receptors (ERs) and ER-co-regulators such as MLL-histone methylase (MLL3), histone acetylases, CBP/P300, bind to the HOXB9 promoter EREs in the presence of BPA, modify chromatin (histone methylation and acetylation) and lead to gene activation. In summary, our results demonstrate that BPA exposure, like estradiol, increases HOXB9 expression in breast cells both in vitro and in vivo through a mechanism that involves increased recruitment of transcription and chromatin modification factors.

Comparison of toxicity and teratogenic effects of salen and vo-salen on chicken embryo

OBJECTIVES

The toxic and teratogenic effects of salen (C16H16N2O2) and salen vanadium oxide (VOS) (C16H14N2O3V) were evaluated against chicken embryos along with chicken hepatic and fibroblastic cells in vitro cultures.

METHODS

Salen and VOS complexes were injected in the following concentrations: 5, 10, 20, 40, 80, 160, and 300 μM/egg for salen and 7.5, 15, 75, 120, 150, 240, and 300 μM/egg for VOS. In order to screen for skeletal malformations, the alizarin red clearing and staining method was employed. For studying the cytotoxic effects of these compounds, hepatic and fibroblastic cells were cultured and treated.

RESULTS

Our results show that injecting salen with various concentrations leads to a significant increase in embryonic mortality. Skeletal and morphological malformations resulting from salen injections included ectopic viscera and club foot. Our results show that embryonic mortality increased relative to the control group. In addition, alizarin red staining showed skeletal malformations like deletion of caudal vertebrae.

DISCUSSION

Our comparison showed that salen was a stronger teratogen than VOS, which may be due roles of the vanadium element, whose derivatives show physiological particulars and at low concentrations plays anticancer specifications without toxic effect.

CONCLUSION

Results show that chicken embryos were sensitive to the toxicity of salen and VOS, and these compounds can affect the growth and ossification of the chicken embryos. Moreover, the cytotoxicity of salen and VOS shows that the viability of both salen and VOS-treated cells significantly decreased in a dose-dependent manner.

Bisphenol-A induces expression of HOXC6, an estrogen-regulated homeobox-containing gene associated with breast cancer

HOXC6 is a homeobox-containing gene associated with mammary gland development and is overexpressed in variety of cancers including breast and prostate cancers. Here, we have examined the expression of HOXC6 in breast cancer tissue, investigated its transcriptional regulation via estradiol (E2) and bisphenol-A (BPA, an estrogenic endocrine disruptor) in vitro and in vivo. We observed that HOXC6 is differentially over-expressed in breast cancer tissue. E2 induces HOXC6 expression in cultured breast cancer cells and in mammary glands of Sprague Dawley rats. HOXC6 expression is also induced upon exposure to BPA both in vitro and in vivo. Estrogen-receptor-alpha (ERα) and ER-coregulators such as MLL-histone methylases are bound to the HOXC6 promoter upon exposure to E2 or BPA and that resulted in increased histone H3K4-trimethylation, histone acetylation, and recruitment of RNA polymerase II at the HOXC6 promoter. HOXC6 overexpression induces expression of tumor growth factors and facilitates growth 3D-colony formation, indicating its potential roles in tumor growth. Our studies demonstrate that HOXC6, which is a critical player in mammary gland development, is upregulated in multiple cases of breast cancer, and is transcriptionally regulated by E2 and BPA, in vitro and in vivo.

Tumor-targeting novel manganese complex induces ROS-mediated apoptotic and autophagic cancer cell death

In this study, the antitumor activity of the novel manganese (II) compound, Adpa-Mn {[(Adpa)Mn(Cl)(H(2)O)] (Adpa=bis(2-pyridylmethyl)amino-2-propionic acid)}, and its possible mechanisms of action were investigated. In vitro, the growth inhibitory effects of Adpa-Mn (with IC(50) values lower than 15 µM) on tumor cell lines were examined by MTT assay. We found that this compound was more selective against cancer cells than the popular chemotherapeutic reagent, cisplatin. We then found that Adpa-Mn achieved its selectivity against cancer cells through the transferrin (Tf)-transferrin receptor (TfR) system, which is highly expressed in tumor cells. Furthermore, Adpa-Mn induced both apoptosis and autophagy, as indicated by chromatin condensation, the activation of poly(ADP-ribose) polymerase (PARP), Annexin V/propidium iodide staining, an enhanced fluorescence intensity of monodansylcadaverine (MDC), as well as the elevated expression of the autophagy-related protein, microtubule-associated protein 1 light chain 3 (LC3). In addition, Adpa-Mn induced the generation of intracellular reactive oxygen species (ROS) and its anticancer effects were significantly reduced following pre-treatment with the antioxidant, N-acetyl cysteine, indicating that ROS triggered cell death. In vivo, the induction of apoptosis and autophagy in tumor tissue was confirmed following treatment with Adpa-Mn, which contributed to its significant antitumor activity against hepatocellular carcinoma (Hep-A cell) xenografts at 10 mg/kg. Taken together, these data suggest the possible use of Adpa-Mn as a novel anticancer drug.

An α1-adrenergic receptor ligand repurposed as a potent antiproliferative agent for head and neck squamous cell carcinoma

In this study we report the anticancer properties of RN5-Me, an α₁-adrenergic receptor ligand.

Mononuclear iron(iii) complexes of tridentate ligands with efficient nuclease activity and studies of their cytotoxicity

Mono- and bis-chelated iron(iii) complexes derived from phenolato-based tridentate ligands have been synthesised and characterized. These complexes show electrostatic DNA interactions and efficient DNA cleavage via OH˙ radicals, and induce cytotoxicity in MCF7 cell lines.

A novel manganese complex LMnAc selectively kills cancer cells by induction of ROS-triggered and mitochondrial-mediated cell death

We previously identified a novel synthesized metal compound, LMnAc ([L2Mn2(Ac)(H2O)2](Ac) (L=bis(2-pyridylmethyl) amino-2-propionic acid)). This compound exhibited significant inhibition on cancer cell proliferation and was more selective against cancer cells than was the popular chemotherapeutic reagent cisplatin. In this study, we further investigated the underlying molecular mechanisms of LMnAc-induced cancer cell death. We found that LMnAc achieved its selectivity against cancer cells through the transferrin-transferrin receptor system, which is highly expressed in tumor cells. LMnAc triggered cancer cells to commit autophagy and apoptosis, which was mediated by the mitochondrial pathway. Moreover, LMnAc disrupted mitochondrial function, resulting in mitochondrial membrane potential collapse and ATP reduction. In addition, LMnAc induced intracellular Ca(2+) overload and reactive oxygen species generation. Interestingly, its anticancer effect was significantly reduced following pretreatment with the antioxidant N-acetyl cysteine, indicating that reactive oxygen species triggered cell death. Altogether, our data suggest that LMnAc appears to be a selectively promising anticancer drug candidate.

Structure-activity relationship for Fe(III)-salen-like complexes as potent anticancer agents

Quantitative structure activity relationship (QSAR) for the anticancer activity of Fe(III)-salen and salen-like complexes was studied. The methods of density function theory (B3LYP/LANL2DZ) were used to optimize the structures. A pool of descriptors was calculated: 1497 theoretical descriptors and quantum-chemical parameters, shielding NMR, and electronic descriptors. The study of structure and activity relationship was performed with multiple linear regression (MLR) and artificial neural network (ANN). In nonlinear method, the adaptive neuro-fuzzy inference system (ANFIS) was applied in order to choose the most effective descriptors. The ANN-ANFIS model with high statistical significance (R²_train = 0.99, RMSE = 0.138, and Q²_LOO = 0.82) has better capability to predict the anticancer activity of the new compounds series of this family. Based on this study, anticancer activity of this compound is mainly dependent on the geometrical parameters, position, and the nature of the substituent of salen ligand.

Long noncoding RNAs: emerging stars in gene regulation, epigenetics and human disease

Noncoding RNAs (ncRNAs) are classes of transcripts that are encoded by the genome and transcribed but never get translated into proteins. Though not translated into proteins, ncRNAs play pivotal roles in a variety of cellular functions. Here, we review the functions of long noncoding RNAs (lncRNAs) and their implications in various human diseases. Increasing numbers of studies demonstrate that lncRNAs play critical roles in regulation of protein-coding genes, maintenance of genomic integrity, dosage compensation, genomic imprinting, mRNA processing, cell differentiation, and development. Misregulation of lncRNAs is associated with a variety of human diseases, including cancer, immune and neurological disorders. Different classes of lncRNAs, their functions, mechanisms of action, and associations with different human diseases are summarized in detail, highlighting their as yet untapped potential in therapy.

Mitochondria are the primary target in the induction of apoptosis by chiral ruthenium(II) polypyridyl complexes in cancer cells

A series of novel chiral ruthenium(II) polypyridyl complexes (Δ-Ru1, Λ-Ru1, Δ-Ru2, Λ-Ru2, Δ-Ru3, Λ-Ru3) were synthesized and evaluated to determine their antiproliferative activities. Colocalization, inductively coupled plasma mass spectrometry, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay studies showed that these ruthenium(II) complexes accumulated preferentially in the mitochondria and exhibited cytotoxicity against various cancer cells in vitro. The complex Δ-Ru1 is of particular interest because it was found to have half-maximal inhibitory concentrations comparable to those of cisplatin and better activity than cisplatin against a cisplatin-resistant cell line, A549-CP/R. Δ-Ru1 induced alterations in the mitochondrial membrane potential and triggered intrinsic mitochondria-mediated apoptosis in HeLa cells, which involved the regulation of Bcl-2 family members and the activation of caspases. Taken together, these data suggest that Δ-Ru1 may be a novel mitochondria-targeting anticancer agent.

Interaction of manganese(II) complex with apotransferrin and the apotransferrin enhanced anticancer activities

Apotransferrin could bind a number of metal ions besides Fe, which makes it an attractive delivery vehicle for metal-based medicines. In order to evaluate whether anticancer Mn(II) complex of [(Adpa)Mn(Cl)(H(2)O)] Adpa=bis(2-pyridylmethyl)amino-2-propionic acid) (AdpaMn) could be transported by apotransferrin, we investigated its interaction with human apotransferrin by fluorescence and circular dichroism spectroscopy (CD). The association dynamics show that AdpaMn could bind to apotransferrin spontaneously in Hepes buffer. Synchronous fluorescence spectroscopy and CD spectroscopy show that the conjugation of AdpaMn and apotransferrin by hydrophobic interactions induces the change of the microenvironment and conformation of apotransferrin. The reversible binding and release of AdpaMn was studied with fluorescence titration method. The AdpaMn complex can be released from the AdpaMn-apotransferrin entity in weak acid environments. MTT assay in vitro confirms that apotransferrin can enhance the inhibition rate of AdpaMn on the proliferation of HepG-2 cells, so we deduce that AdpaMn could be transported by apotransferrin in vivo.

Antisense oligonucleotide mediated knockdown of HOXC13 affects cell growth and induces apoptosis in tumor cells and over expression of HOXC13 induces 3D-colony formation

HOXC13 is a homeobox containing gene that plays crucial roles in hair development and origin of replication. Herein, we investigated the biochemical functions of HOXC13 and explored its potential roles in tumor cell viability. We have designed a phosphorothioate based antisense-oligonucleotide that specifically knockdown HOXC13 in cultured cells. Cell viability and cytotoxicity assays demonstrated that HOXC13 is essential for cell growth and viability. Antisense-mediated knockdown of HOXC13 affected the cell viability and induced apoptosis in cultured tumor cells. HOXC13 regulates the expression of cyclins and antisense-mediated knockdown of HOXC13 resulted in cell cycle arrest and apoptosis in colon cancer cells. Finally over expression of HOXC13 resulted in 3D-colony formation in soft-agar assay indicating its potential roles in cell proliferation and tumorigenesis.