Targeting myeloid-derived suppressor cells in combination with tumor cell vaccination predicts anti-tumor immunity and breast cancer dormancy: an in silico experiment.

Among the different breast cancer subsets, triple-negative breast cancer (TNBC) has the worst prognosis and limited options for targeted therapies. Immunotherapies are emerging as novel treatment opportunities for TNBC. However, the surging immune response elicited by immunotherapies to eradicate cancer cells can select resistant cancer cells, which may result in immune escape and tumor evolution and progression. Alternatively, maintaining the equilibrium phase of the immune response may be advantageous for keeping a long-term immune response in the presence of a small-size residual tumor. Myeloid-derived suppressor cells (MDSCs) are activated, expanded, and recruited to the tumor microenvironment by tumor-derived signals and can shape a pro-tumorigenic micro-environment by suppressing the innate and adaptive anti-tumor immune responses. We recently proposed a model describing immune-mediated breast cancer dormancy instigated by a vaccine consisting of dormant, immunogenic breast cancer cells derived from the murine 4T1 TNBC-like cell line. Strikingly, these 4T1-derived dormant cells recruited fewer MDSCs compared to aggressive 4T1 cells. Recent experimental studies demonstrated that inactivating MDSCs has a profound impact on reconstituting immune surveillance against the tumor. Here, we developed a deterministic mathematical model for simulating MDSCs depletion from mice bearing aggressive 4T1 tumors resulting in immunomodulation. Our computational simulations indicate that a vaccination strategy with a small number of tumor cells in combination with MDSC depletion can elicit an effective immune response suppressing the growth of a subsequent challenge with aggressive tumor cells, resulting in sustained tumor dormancy. The results predict a novel therapeutic opportunity based on the induction of effective anti-tumor immunity and tumor dormancy.

Thymol Nanopolymer Synthesis and Its Effects on Morphine Withdrawal Syndrome in Comparison With Clonidine in Rats.

The drug delivery system is valuable in the treatment of the disease. A nanopolymer as a thymol and Thymbra spicata release system was synthesized and its effects on morphine withdrawal syndrome in comparison with clonidine in rats were studied. The nanopolymer was characterized by different methods, namely, IR, HNMR, CNMR, GPC, DLS, and AFM. Thymol in T. spicata extract was assessed. The loading and release rate of thymol and T. spicata extract on the nanopolymer were evaluated by HPLC. The median lethal dose (LD50) of the T. spicata extract, thymol, extract nanopolymer, and thymol nanopolymer was studied. The frequency of jumping, rearing, and teeth chattering in naloxone-induced morphine withdrawal syndrome was studied. Synthesized nanopolymer was desirable as a carrier for the drug. The loaded amount of extract and thymol on nanopolymer was estimated 55 ± 3.2% and 48 ± 2.6% and the drug released was 71 and 68%, respectively. LD50 of the T. spicata extract, thymol, extract nanopolymer, and thymol nanopolymer was 975, 580, 1,250, and 650 mg/kg, respectively. This study showed that thymol nanopolymer was more effective than clonidine to reduce the frequency of morphine withdrawal symptoms. Our results suggest that T. spicata extract, thymol, extract nanopolymer, and thymol nanopolymer are mighty in reducing the narcotic withdrawal signs. The mechanism of action and therapeutic potential is maybe similar to clonidine.

Dormant Tumor Cell Vaccination: A Mathematical Model of Immunological Dormancy in Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is a molecular subtype of breast malignancy with a poor clinical prognosis. There is growing evidence that some chemotherapeutic agents induce an adaptive anti-tumor immune response. This reaction has been proposed to maintain the equilibrium phase of the immunoediting process and to control tumor growth by immunological cancer dormancy. We recently reported a model of immunological breast cancer dormancy based on the murine 4T1 TNBC model. Treatment of 4T1 cells in vitro with high-dose chemotherapy activated the type I interferon (type I IFN) signaling pathway, causing a switch from immunosuppressive to cytotoxic T lymphocyte-dependent immune response in vivo, resulting in sustained dormancy. Here, we developed a deterministic mathematical model based on the assumption that two cell subpopulations exist within the treated tumor: one population with high type I IFN signaling and immunogenicity and lower growth rate; the other population with low type I IFN signaling and immunogenicity and higher growth rate. The model reproduced cancer dormancy, elimination, and immune-escape in agreement with our previously reported experimental data. It predicted that the injection of dormant tumor cells with active type I IFN signaling results in complete growth control of the aggressive parental cancer cells injected at a later time point, but also of an already established aggressive tumor. Taken together, our results indicate that a dormant cell population can suppress the growth of an aggressive counterpart by eliciting a cytotoxic T lymphocyte-dependent immune response.

Treatment Outcomes and Clinicopathologic Characteristics of Triple-Negative Breast Cancer: A Report from Cancer Institute of Iran.

Background: Triple-negative breast cancers (TNBC) have a more aggressive course and are associated with poorer prognosis in comparison with other subtypes of breast cancer. One of the most common subtypes of TNBC is basal-like. The aim of this study was to investigate clinicopathological characteristics and clinical course of TNBC in Iranian women and compare them with other studies. Subjects and Methods: Between March 2009 and February 2011, patients with breast cancer in Cancer Institute of Iran were selected and then followed-up for 2 years. Paraffin-embedded tumor block of all TNBC patients were evaluated for CK5/6 and EGFR using IHC method. Results: Among 267 breast cancer patients, 60 cases with TNBC were identified (22.5%), 31 patients (51.7%) had basal-like and 29 patients (48.3%) had non-basal-like tumors. The median age of participants with TNBC was 49.6 years. Among our patients, 70% had positive lymph nodes.93.4% of all patients at the time of diagnosis were stage II or III and tumor size was at least 3 centimeters. No grade 1 TNBC was found in this study. During the follow-up period, there were 26 recurrences and 7 deaths. Conclusion: The percentage of basal-like subtype among Iranian women with TNBC was lower compared to other studies, while bone metastases, clinical stage, lymph node involvement and tumor size were higher. Clinicopathological findings in basal and non-basal-like subgroups were not different, but the probability of lymph node involvement was more common in patients who were EGFR positive.

The ionic environment determines ribozyme cleavage rate by modulation of nucleobase pK a.

Several small ribozymes employ general acid-base catalysis as a mechanism to enhance site-specific RNA cleavage, even though the functional groups on the ribonucleoside building blocks of RNA have pK (a) values far removed from physiological pH. The rate of the cleavage reaction is strongly affected by the identity of the metal cation present in the reaction solution; however, the mechanism(s) by which different cations contribute to rate enhancement has not been determined. Using the Neurospora VS ribozyme, we provide evidence that different cations confer particular shifts in the apparent pK (a) values of the catalytic nucleobases, which in turn determines the fraction of RNA in the protonation state competent for general acid-base catalysis at a given pH, which determines the observed rate of the cleavage reaction. Despite large differences in observed rates of cleavage in different cations, mathematical models of general acid-base catalysis indicate that k (1), the intrinsic rate of the bond-breaking step, is essentially constant irrespective of the identity of the cation(s) in the reaction solution. Thus, in contrast to models that invoke unique roles for metal ions in ribozyme chemical mechanisms, we find that most, and possibly all, of the ion-specific rate enhancement in the VS ribozyme can be explained solely by the effect of the ions on nucleobase pK (a). The inference that k (1) is essentially constant suggests a resolution of the problem of kinetic ambiguity in favor of a model in which the lower pK (a) is that of the general acid and the higher pK (a) is that of the general base.

An important role of G638 in the cis-cleavage reaction of the Neurospora VS ribozyme revealed by a novel nucleotide analog incorporation method.

We describe a chemical coupling procedure that allows joining of two RNAs, one of which contains a site-specific base analog substitution, in the absence of divalent ions. This method allows incorporation of nucleotide analogs at specific positions even into large, cis-cleaving ribozymes. Using this method we have studied the effects of substitution of G638 in the cleavage site loop of the VS ribozyme with a variety of purine analogs having different functional groups and pK(a) values. Cleavage rate versus pH profiles combined with kinetic solvent isotope experiments indicate an important role for G638 in proton transfer during the rate-limiting step of the cis-cleavage reaction.