Real-World Evidence of Efficacy and Safety of Levonadifloxacin (Oral and IV) in the Management of Acute Bacterial Skin and Skin Structure Infections (ABSSSI): Findings of a Retrospective, Multi-Center Study.

Background Antimicrobial resistance by bacteria poses a substantial threat to the success in the treatment of acute bacterial skin and skin structure infections (ABSSSI). Levonadifloxacin is a novel benzoquinolizine subclass of quinolone which has a broad spectrum of activity, available in both oral and intravenous formulations for the treatment of skin structure infections caused by Gram-positive pathogens including methicillin-resistant Staphylococcus aureus (MRSA). Patients and methods This prescription event monitoring study captured data of 227 patients receiving levonadifloxacin (oral and/or IV) in a real-world setting to assess the safety and efficacy in the treatment of ABSSSI. Study outcomes were a clinical and microbial success at the end of therapy and safety was assessed based on adverse events reported. Results One hundred and forty patients received IV levonadifloxacin therapy, 76 patients received oral alalevonadifloxacin, and 11 received IV followed by oral therapy. The mean duration of therapy was 7.3 days. Out of 227 patients, MRSA isolates were identified in 79 patients. Clinical success rates with oral, IV, and IV followed by oral levonadifloxacin therapy were 97.3%, 97.8%, and 100% respectively. The overall microbial success rate was 99.2% and only two patients reported two adverse events. Conclusions The excellent safety and efficacy profile of levonadifloxacin on oral and/or intravenous therapy, makes it a desirable treatment modality for management of ABSSSI. Unique features of levonadifloxacin such as availability of both IV and oral form, minimal drug-drug interactions, exemption from dosage adjustment in renal and hepatic impaired patients and a broad spectrum of coverage, makes it a suitable agent meeting several unmet clinical needs in contemporary patients.

Prescription-Event Monitoring Study on Safety and Efficacy of Levonadifloxacin (Oral and I.V.) in Management of Bacterial Infections: Findings of Real-World Observational Study.

Background: Levonadifloxacin is a novel broad-spectrum antibiotic belonging to the benzoquinolizine subclass of quinolones. It is available in intravenous as well as oral formulation for the treatment of infections caused by common Gram-positive bacterial pathogens including methicillin-resistant Staphylococcus aureus (MRSA). Patients and Methods: This study retrospectively assessed the real-world safety and efficacy of levonadifloxacin (oral and/or IV) in the treatment of 1229 patients across various clinical conditions. Study outcomes were clinical and microbiological success at the end of therapy. Results: The mean duration of levonadifloxacin therapy was 7.2 days, with a time to clinical improvement averaging at 4 days. Three hundred and three patients received oral therapy, 875 received IV, and 51 received a combination of IV followed by oral therapy. Patients were prescribed levonadifloxacin for skin and soft-tissue infections, diabetic foot infections, septicemia, catheter-related bloodstream infections, bone and joint infections, febrile neutropenia, and respiratory infections including COVID-19 pneumonia. High clinical success rates of 98.3%, 93.7%, and 96.1% with oral, IV, and IV followed by oral levonadifloxacin, respectively, were obtained. Only 11 mild adverse events were reported in 9 patients which included constipation, diarrhea, hyperglycemia, nausea, fatigue, and vomiting. Overall, 96.3% and 97.3% of investigators rated the efficacy and safety of levonadifloxacin as "good to excellent." Conclusions: An excellent safety and efficacy profile of levonadifloxacin was observed in this study making it a suitable treatment option for management of various bacterial infections, including those caused by resistant Gram-positive pathogens such as MRSA and quinolone-resistant S. aureus.

Metabolic Adaptations in Cancer Stem Cells.

Cancer stem cells (CSCs) are a small and elusive subpopulation of self-renewing cancer cells with remarkable ability to initiate, propagate, and spread the malignant disease. In addition, they exhibit increased resistance to anticancer therapies, thereby contributing to disease relapse. CSCs are reported to be present in many tumor types such as melanoma, sarcoma, mammary tumors, colon cancer and other solid tumors. These cells from different tumors show unique energetic and metabolic pathways. For example, CSCs from one type of tumor may predominantly use aerobic glycolysis, while from another tumor type may utilize oxidative phosphorylation. Most commonly these cells use fatty acid oxidation and ketone bodies as the main source of energy production. CSCs have a remarkable ability to reprogram their metabolism in order to survive under adverse conditions such as hypoxia, acidosis, and starvation. There is increasing interest to identify molecular targets that can be utilized to kill CSCs and to control their growth. In this review, we discuss how an understanding of the unique metabolism of CSCs from different tumors can offer promising strategies for targeting CSCs and hence to prevent disease relapse and to treat the metastatic disease.

Transglutaminase-2: evolution from pedestrian protein to a promising therapeutic target.

The ability of cancer cells to metastasize represents the most devastating feature of cancer. Currently, there are no specific biomarkers or therapeutic targets that can be used to predict the risk or to treat metastatic cancer. Many recent reports have demonstrated elevated expression of transglutaminase 2 (TG2) in multiple drug-resistant and metastatic cancer cells. TG2 is a multifunctional protein mostly known for catalyzing Ca2+-dependent -acyl transferase reaction to form protein crosslinks. Besides this transamidase activity, many Ca2+-independent and non-enzymatic activities of TG2 have been identified. Both, the enzymatic and non-enzymatic activities of TG2 have been implicated in diverse pathophysiological processes such as wound healing, cell growth, cell survival, extracellular matrix modification, apoptosis, and autophagy. Tumors have been frequently referred to as 'wounds that never heal'. Based on the observation that TG2 plays an important role in wound healing and inflammation is known to facilitate cancer growth and progression, we discuss the evidence that TG2 can reprogram inflammatory signaling networks that play fundamental roles in cancer progression. TG2-regulated signaling bestows on cancer cells the ability to proliferate, to resist cell death, to invade, to reprogram glucose metabolism and to metastasize, the attributes that are considered important hallmarks of cancer. Therefore, inhibiting TG2 may offer a novel therapeutic approach for managing and treatment of metastatic cancer. Strategies to inhibit TG2-regulated pathways will also be discussed.

Prevention and Treatment of Cancer: Hypes and Hopes 6th International Translational Cancer Research Conference.

Cancer is primarily an "old-age" disease that has an "age-old" history. The overall incidence of cancer is much higher in Western countries, but is rapidly growing in Eastern countries perhaps due to change in life-style. Almost three million studies published to date indicate that cancer is a hyperproliferative disorder that arises from dysregulation of multiple cell signaling pathways. The cancer genome landscape indicates that approximately 140 genes and 12 cell signaling pathways drive almost all cancers. "Targeted therapy," a buzz word in cancer treatment for the past two decades, has provided antibodies, as well as small-molecule inhibitors. These therapies have been successful only in few instances. However, in most cases, minor increase in overall survival has been reported at the cost of huge expense. An alternative strategy is to prevent cancer or to diagnose and treat the disease at an early stage to gain survival benefits. Such interventions are also cost-effective. To address some of these issues, the 6th International Translational Cancer Research Conference was held during February 4-7th, 2016, in Ahmedabad, Gujarat, India; the homeland of Mahatma Gandhi. This conference was focused on utilizing multidisciplinary approaches for prevention and early treatment that would likely simultaneously or sequentially target many key pathways. Several distinguished speakers were invited from around the world. This article highlights primary features of this conference.

A multi-targeted approach to suppress tumor-promoting inflammation.

Cancers harbor significant genetic heterogeneity and patterns of relapse following many therapies are due to evolved resistance to treatment. While efforts have been made to combine targeted therapies, significant levels of toxicity have stymied efforts to effectively treat cancer with multi-drug combinations using currently approved therapeutics. We discuss the relationship between tumor-promoting inflammation and cancer as part of a larger effort to develop a broad-spectrum therapeutic approach aimed at a wide range of targets to address this heterogeneity. Specifically, macrophage migration inhibitory factor, cyclooxygenase-2, transcription factor nuclear factor-κB, tumor necrosis factor alpha, inducible nitric oxide synthase, protein kinase B, and CXC chemokines are reviewed as important antiinflammatory targets while curcumin, resveratrol, epigallocatechin gallate, genistein, lycopene, and anthocyanins are reviewed as low-cost, low toxicity means by which these targets might all be reached simultaneously. Future translational work will need to assess the resulting synergies of rationally designed antiinflammatory mixtures (employing low-toxicity constituents), and then combine this with similar approaches targeting the most important pathways across the range of cancer hallmark phenotypes.

Multi-targeted approach to cancer treatment: an international translational cancer research symposium.

Whether it is chronic myeloid leukemia, ALK-expressing malignancies, or HER2-positive breast cancer, targeted-therapies for treatment of human cancers have shown great promise. However, as they hit a single molecule expressed in neoplastic cells, their use is frequently associated with development of resistance. In cancer cells many signaling pathways operate in parallel, hence the idea of multi-targeted therapy is prevailing. The Society of Translational Cancer Research held its biennial meeting in the capital city of India, Delhi from February 6th through 9th, 2014 to discuss 'Multi-targeted Approach to Treatment of Cancer'. Over 200 scientists, clinicians, trainees, and industry representatives from different countries gathered in Vigyan Bhavan, the hotspot of Delhi for four days to talk and discuss on a variety of topics related to multi-targeted therapeutic approaches. Talks were presented by leaders in the cancer research field from various countries. It became clear from this conference that coupling multiple targeted-agents or using an agent that hits an individual target in several independent locations in the disease-causing pathway(s) may be the best approach to treat different cancers.

Protective effect of melatonin on propoxur-induced impairment of memory and oxidative stress in rats.

Propoxur (a carbamate pesticide) has been shown to adversely affect memory and induce oxidative stress on both acute and chronic exposure. This study was designed to explore the modulation of the effects of propoxur over cognitive function by melatonin (MEL). Cognitive function was assessed using step-down latency (SDL) on a passive avoidance apparatus, and transfer latency (TL) on an elevated plus maze. Oxidative stress was assessed by examining brain malondialdehyde (MDA) and reduced glutathione (GSH) levels and catalase (CAT) activity. A significant reduction in SDL and prolongation of TL was observed for the propoxur (10 mg/kg/d; p.o.) treated group at weeks 6 and 7 when compared with control. One week treatment with MEL (50 mg/kg/d; i.p.) antagonized the effect of propoxur on SDL, as well as TL. Propoxur produced a statistically significant increase in the brain MDA levels and decrease in the brain GSH levels and CAT activity. Treatment with MEL attenuated the effect of propoxur on oxidative stress. The results of the present study thus show that MEL has the potential to attenuate cognitive dysfunction and oxidative stress induced by toxicants like propoxur in the brain.

Transglutaminase regulation of cell function.

Transglutaminases (TGs) are multifunctional proteins having enzymatic and scaffolding functions that participate in regulation of cell fate in a wide range of cellular systems and are implicated to have roles in development of disease. This review highlights the mechanism of action of these proteins with respect to their structure, impact on cell differentiation and survival, role in cancer development and progression, and function in signal transduction. We also discuss the mechanisms whereby TG level is controlled and how TGs control downstream targets. The studies described herein begin to clarify the physiological roles of TGs in both normal biology and disease states.

Tissue transglutaminase expression promotes castration-resistant phenotype and transcriptional repression of androgen receptor.

Many studies have supported a role for inflammation in prostate tumour growth. However, the contribution of inflammation to the development of castration-resistant prostate cancer remains largely unknown. Based on observations that aberrant expression of the proinflammatory protein tissue transglutaminase (TG2) is associated with development of drug resistance and metastatic phenotype in multiple cancer types, we determined TG2 expression in prostate cancer cells. Herein we report that human prostate cancer cell lines with low expression of androgen receptor (AR) had high basal levels of TG2 expression. Also, overexpression of TG2 negatively regulated AR mRNA and protein expression and attenuated androgen sensitivity of prostate cancer cells. TG2 expression in prostate cancer cells was associated with increased invasion and resistance to chemotherapy. Mechanistically, TG2 activated nuclear factor (NF)-κB and induced epithelial-mesenchymal transition. TG2/NF-κB-mediated decrease in AR expression resulted from transcriptional repression involving cis-interaction of NF-κB in a complex with TG2 with the 5'-untranslated region of AR. Negative regulation of AR could be partially abrogated by repression of TG2 or NF-κB (p65/RelA) by gene-specific small interfering RNA. These results suggested that a novel pathway links androgen dependence with TG2-regulated inflammatory signalling and hence may make TG2 a novel therapeutic target for the prevention and treatment of castration-resistant prostate cancer.

Transglutaminase 2 reprogramming of glucose metabolism in mammary epithelial cells via activation of inflammatory signaling pathways.

Aberrant glucose metabolism characterized by high levels of glycolysis, even in the presence of oxygen, is an important hallmark of cancer. This metabolic reprogramming referred to as the Warburg effect is essential to the survival of tumor cells and provides them with substrates required for biomass generation. Molecular mechanisms responsible for this shift in glucose metabolism remain elusive. As described herein, we found that aberrant expression of the proinflammatory protein transglutaminase 2 (TG2) is an important regulator of the Warburg effect in mammary epithelial cells. Mechanistically, TG2 regulated metabolic reprogramming by constitutively activating nuclear factor (NF)-κB, which binds to the hypoxia-inducible factor (HIF)-1α promoter and induces its expression even under normoxic conditions. TG2/NF-κB-induced increase in HIF-1α expression was associated with increased glucose uptake, increased lactate production and decreased oxygen consumption by mitochondria. Experimental suppression of TG2 attenuated HIF-1α expression and reversed downstream events in mammary epithelial cells. Moreover, downregulation of p65/RelA or HIF-1α expression in these cells restored normal glucose uptake, lactate production, mitochondrial respiration and glycolytic protein expression. Our results suggest that aberrant expression of TG2 is a master regulator of metabolic reprogramming and facilitates metabolic alterations in epithelial cells even under normoxic conditions. A TG2-induced shift in glucose metabolism helps breast cancer cells to survive under stressful conditions and promotes their metastatic competence.

Combating resistance to anti-IGFR antibody by targeting the integrin ß3-Src pathway.

BACKGROUND: Several phase II/III trials of anti-insulin-like growth factor 1 receptor (IGF-1R) monoclonal antibodies (mAbs) have shown limited efficacy. The mechanisms of resistance to IGF-1R mAb-based therapies and clinically applicable strategies for overcoming drug resistance are still undefined. METHODS: IGF-1R mAb cixutumumab efficacy, alone or in combination with Src inhibitors, was evaluated in 10 human head and neck squamous cell carcinoma (HNSCC) and six non-small cell lung cancer (NSCLC) cell lines in vitro in two- or three-dimensional culture systems and in vivo in cell line- or patient-derived xenograft tumors in athymic nude mice (n = 6-9 per group). Cixutumumab-induced changes in cell signaling and IGF-1 binding to integrin ß3 were determined by Western or ligand blotting, immunoprecipitation, immunofluorescence, and cell adhesion analyses and enzyme-linked immunosorbent assay. Data were analyzed by the two-sided Student t test or one-way analysis of variance. RESULTS: Integrin ß3-Src signaling cascade was activated by IGF-1 in HNSCC and NSCLC cells, when IGF-1 binding to IGF-1R was hampered by cixutumumab, resulting in Akt activation and cixutumumab resistance. Targeting integrin ß3 or Src enhanced antitumor activity of cixutumumab in multiple cixutumumab-resistant cell lines and patient-derived tumors in vitro and in vivo. Mean tumor volume of mice cotreated with cixutumumab and integrin ß3 siRNA was 133.7 mm(3) (95% confidence interval [CI] = 57.6 to 209.8 mm(3)) compared with those treated with cixutumumab (1472.5 mm(3); 95% CI = 1150.7 to 1794.3 mm(3); P < .001) or integrin ß3 siRNA (903.2 mm(3); 95% CI = 636.1 to 1170.3 mm(3); P < .001) alone. CONCLUSIONS: Increased Src activation through integrin ανß3 confers considerable resistance against anti-IGF-1R mAb-based therapies in HNSCC and NSCLC cells. Dual targeting of the IGF-1R pathway and collateral integrin ß3-Src signaling module may override this resistance.

Tissue transglutaminase as a central mediator in inflammation-induced progression of breast cancer.

TGM2 is a stress-responsive gene that encodes a multifunctional and structurally complex protein called tissue transglutaminase (abbreviated as TG2 or tTG). TGM2 expression is frequently upregulated during inflammation and wounding. Emerging evidence indicates that TGM2 expression is aberrantly upregulated in multiple cancer cell types, particularly those selected for resistance to chemotherapy and radiation therapy and those isolated from metastatic sites. It is becoming increasingly evident that chronic expression of TG2 in epithelial cancer cells initiates a complex series of signaling networks which contributes to the development of drug resistance and an invasive phenotype. For example, forced or basal high expression of TG2 in mammary epithelial cells is associated with activation of nuclear transcription factor-kappa B (NF-κB), Akt, focal adhesion kinase, and hypoxia-inducible factor. All of these changes are considered hallmarks of aggressive tumors. TG2 expression is able to induce the developmentally regulated program of epithelial-to-mesenchymal transition (EMT) and to confer cancer stem cell (CSC) traits in mammary epithelial cells; both EMT and CSCs have been implicated in cancer metastasis and resistance to standard therapies. Importantly, TG2 expression in tumor samples is associated with poor disease outcome, increased drug resistance, and increased incidence of metastasis. These observations imply that TG2 plays a crucial role in promoting an aggressive phenotype in mammary epithelial cells. In this review, we discuss recent evidence that TG2-regulated pathways contribute to the aggressive phenotype in breast cancer.

Meeting report: leaders in translational cancer research meet in Udaipur, a historical town of India: an International Symposium onTranslational Cancer Research: Cancer Prevention. Udaipur, Rajasthan, India, december 16-19, 2011.

Like most countries in the Western world, most non-communicable diseases, such as cancer, are very much on the rise. Extensive research suggests that cancer is a preventable disease that requires a major change in lifestyle. The fourth International Translational Cancer Research Symposium on Cancer Prevention was convened from Dec. 16th through Dec. 19th, 2011 in Udaipur, Rajasthan, the largest state located on the northwestern side of India. Scientists, clinicians, and trainees from different countries participated in this conference to discuss biological processes involved in cancer and various avenues to prevent cancer. It became clear from this conference that tobacco use, alcohol consumption, diet and obesity, radiation, and pollution may account for many carcinomas.

Label-free recognition of drug resistance via impedimetric screening of breast cancer cells.

We present a novel study on label-free recognition and distinction of drug resistant breast cancer cells (MCF-7 DOX) from their parental cells (MCF-7 WT) via impedimetric measurements. Drug resistant cells exhibited significant differences in their dielectric properties compared to wild-type cells, exerting much higher extracellular resistance (Rextra ). Immunostaining revealed that MCF-7 DOX cells gained a much denser F-actin network upon acquiring drug resistance indicating that remodeling of actin cytoskeleton is probably the reason behind higher Rextra , providing stronger cell architecture. Moreover, having exposed both cell types to doxorubicin, we were able to distinguish these two phenotypes based on their substantially different drug response. Interestingly, impedimetric measurements identified a concentration-dependent and reversible increase in cell stiffness in the presence of low non-lethal drug doses. Combined with a profound frequency analysis, these findings enabled distinguishing distinct cellular responses during drug exposure within four concentration ranges without using any labeling. Overall, this study highlights the possibility to differentiate drug resistant phenotypes from their parental cells and to assess their drug response by using microelectrodes, offering direct, real-time and noninvasive measurements of cell dependent parameters under drug exposure, hence providing a promising step for personalized medicine applications such as evaluation of the disease progress and optimization of the drug treatment of a patient during chemotherapy.

Tissue transglutaminase, inflammation, and cancer: how intimate is the relationship?

Despite significant advances in surgery and biology, cancer remains a major health problem. It is now well accepted that metastasis and cancer cells' acquired or inherent resistance to conventional therapies are major roadblocks to successful treatment. Chronic inflammation is an important driving force that provides a favorable platform for cancer's progression and development and suggests a link between inflammation and metastatic transformation. However, how chronic inflammation contributes to metastatic cell transformation is not well understood. According to the current theory of cancer progression, a small subpopulation of cancer stem cells (CSCs) in tumors is responsible for their metastasis, resistance, and sustenance. Whether CSCs originate from normal stem cells or from dedifferentiation of terminally differentiated cells remains unknown. Recent evidence indicates that stem cells are not unique; malignant or nonmalignant cells can reprogram and de-differentiate to acquire a stemness phenotype. Thus, phenotypic plasticity may exist between stem cells and non-stem cells, and a dynamic equilibrium may exist between the two phenotypes. Moreover, this equilibrium may shift in one direction or another on the basis of contextual signals in the microenvironment that influence the interconversion between stem and non-stem cell compartments. Whether the inflammatory microenvironment influences this interconversion and shifts the dynamic equilibrium towards stem cell compartments remains unknown. We recently found that aberrant tissue transglutaminase (TG2) expression induces the mesenchymal transition (EMT) and stem cell characteristics in epithelial cells. This finding, in conjunction with the observation that inflammatory signals (e.g., TGFß, TNFα, and NF-κB) which induce EMT, also induce TG2 expression, suggests a possible link between TG2, inflammation, and cancer progression. In this review, we summarize TG2-driven processes in inflammation and their implications in cancer progression.

Tissue transglutaminase constitutively activates HIF-1α promoter and nuclear factor-κB via a non-canonical pathway.

Constitutive activation of nuclear factor kappa B (NF-κB) has been linked with carcinogenesis and cancer progression, including metastasis, chemoresistance, and radiation resistance. However, the molecular mechanisms that result in constitutive activation of NF-κB are poorly understood. Here we show that chronic expression of the pro-inflammatory protein tissue transglutaminase (TG2) reprograms the transcription regulatory network in epithelial cells via constitutive activation of NF-κB. TG2-induced NF-κB binds the functional NF-κB binding site in hypoxia-inducible factor-1 (HIF-1α) promoter and results in its increased expression at transcription and protein levels even under normoxic conditions. TG2/NF-κB-induced HIF-1 was deemed essential for increased expression of some transcription repressors, like Zeb1, Zeb2, Snail, and Twist. Unlike tumor necrosis factor-alpha (TNFα), TG2 did not require IκB kinase (IKK) for NF-κB activation. Our data suggest that TG2 binds with IκBα and results in its rapid degradation via a non-proteasomal pathway. Importantly, the catalytically inactive (C277S) mutant form of TG2 was as effective as was wild-type TG2 in activating NF-κB and inducing HIF-1 expression. We also found that TG2 interacted with p65/RelA protein, both in the cytosolic and the nuclear compartment. The TG2/p65(NF-κB) complex binds to the HIF-1 promoter and induced its transcriptional regulation. Inhibition of TG2 or p65/RelA also inhibited the HIF-1α expression and attenuated Zeb1, Zeb2, and Twist expression. To our knowledge, these findings show for the first time a direct link between TG2, NF-κB, and HIF-1α, demonstrating TG2's important role in cancer progression.

Evidence that GTP-binding domain but not catalytic domain of transglutaminase 2 is essential for epithelial-to-mesenchymal transition in mammary epithelial cells.

INTRODUCTION: The expression of proinflammatory protein tissue transglutaminase 2 (TG2) is frequently upregulated in multiple cancer cell types. However, the exact role of TG2 in cancer cells is not well-understood. We recently initiated studies to determine the significance of TG2 in cancer cells and observed that sustained expression of TG2 resulted in epithelial-to-mesenchymal transition (EMT) and promoted cancer stem cell (CSC) traits in mammary epithelial cells. These results suggested that TG2 could serve as a promising therapeutic target for overcoming chemoresistance and inhibiting metastatic spread of cancer cells. METHODS: Using various mutant constructs, we analyzed the activity of TG2 that is essential for promoting the EMT-CSC phenotype. RESULTS: Our results suggest that catalytically inactive TG2 (TG2-C277S) is as effective as wild-type TG2 (TG2-WT) in inducing the EMT-CSC in mammary epithelial cells. In contrast, overexpression of a GTP-binding-deficient mutant (TG2-R580A) was completely incompetent in this regard. Moreover, TG2-dependent activation of the proinflammatory transcription factor NF-κB is deemed essential for promoting the EMT-CSC phenotype in mammary epithelial cells. CONCLUSIONS: Our results suggest that the transamidation activity of TG2 is not essential for promoting its oncogenic functions and provide a strong rationale for developing small-molecule inhibitors to block GTP-binding pockets of TG2. Such inhibitors may have great potential for inhibiting the TG2-regulated pathways, reversing drug resistance and inhibiting the metastasis of cancer cells.

Evidence that aberrant expression of tissue transglutaminase promotes stem cell characteristics in mammary epithelial cells.

Cancer stem cells (CSCs) or tumor initiating cells (TICs) make up only a small fraction of total tumor cell population, but recent evidence suggests that they are responsible for tumor initiation and the maintenance of tumor growth. Whether CSCs/TICs originate from normal stem cells or result from the dedifferentiation of terminally differentiated cells remains unknown. Here we provide evidence that sustained expression of the proinflammatory protein tissue transglutaminase (TG2) confers stem cell like properties in non-transformed and transformed mammary epithelial cells. Sustained expression of TG2 was associated with increase in CD44(high)/CD24(low/-) subpopulation, increased ability of cells to form mammospheres, and acquisition of self-renewal ability. Mammospheres derived from TG2-transfected mammary epithelial cells (MCF10A) differentiated into complex secondary structures when grown in Matrigel cultures. Cells in these secondary structures differentiated into Muc1-positive (luminal marker) and integrin α6-positive (basal marker) cells in response to prolactin treatment. Highly aggressive MDA-231 and drug-resistant MCF-7/RT breast cancer cells, which express high basal levels of TG2, shared many traits with TG2-transfected MCF10A stem cells but unlike MCF10A-derived stem cells they failed to form the secondary structures and to differentiate into Muc1-positive luminal cells when grown in Matrigel culture. Downregulation of TG2 attenuated stem cell properties in both non-transformed and transformed mammary epithelial cells. Taken together, these results suggested a new function for TG2 and revealed a novel mechanism responsible for promoting the stem cell characteristics in adult mammary epithelial cells.

Effect of progesterone on phosphamidon-induced impairment of memory and oxidative stress in rats.

Progesterone (a neurosteroid) is an important modulator of the nervous system functioning. Organophosphorus pesticides like phosphamidon have been shown to adversely affect memory and induce oxidative stress on both acute and chronic exposure. The present study was therefore designed to investigate the effects of progesterone (PROG) on phosphamidon-induced modulation of cognitive function and oxidative stress in rats. Cognitive function was assessed using step-down latency (SDL) on a passive avoidance apparatus and transfer latency (TL) on an elevated plus maze. Oxidative stress was assessed by examining the levels of thiobarbituric acid reactive species (TBARS) and non-protein thiols (NP-SH) in isolated homogenized whole brain samples. The results showed a significant reduction in SDL and prolongation of TL in the phosphamidon (1.74 mg/kg/d; p.o.) treated group at weeks 6 and 8 as compared to the control group. Two weeks treatment with PROG (15 mg/kg/d; i.p.) antagonized the effect of phosphamidon on SDL as well as TL. Phosphamidon alone produced a significant increase in the brain TBARS levels and decrease in the brain NP-SH levels. Treatment with PROG (15 mg/kg/d; i.p.) attenuated the effect of phosphamidon on oxidative stress. Together, the results showed that progesterone attenuated the cognitive dysfunction and increased oxidative stress induced by phosphamidon in the brain.