Long-term clinical evidence of comparable efficacy and toxicity of nivolumab and pembrolizumab in advanced melanoma treatment.

Pembrolizumab and nivolumab (anty-PD-1 antibody) are commonly used for the treatment of melanoma patients. However, their efficacy and safety have never been directly compared, leaving little guidance for clinicians to select the best therapy. The study included patients with inoperable or metastatic melanoma treated in first line with anti-PD-1 immunotherapy (nivolumab or pembrolizumab). In total 1037 patients were enrolled in the study, 455 (44%) patients were treated with pembrolizumab and 582 (56%) with nivolumab. The estimated median overall survival (OS) in the pembrolizumab and nivolumab groups was 17.4 and 20.0 months [ P = 0.2323; hazard ratio (HR), 1.1; 95% confidence interval (CI), 0.94-1.28], respectively, whereas the median progression-free survival (PFS) was 5.6 and 7.5 months ( P = 0.0941; HR, 1.13; 95% CI, 0.98-1.29), respectively. The estimated 2- and 3-year OS in the pembrolizumab and nivolumab groups were 42/34% and 47/37%, respectively, and the PFS was 25/21% and 29/23%, respectively. There were 391 (49%) immune-related adverse events (irAEs) of any grade during treatment, including 133 (42%) related to pembrolizumab treatment and 258 (53%) to nivolumab treatment. A total of 72 (9.6%) irAEs were in G3 or G4, including during pembrolizumab 29 (9%) and nivolumab 48 (11%). There were no differences in OS, PFS and overall response rates between nivolumab and pembrolizumab therapy in previously untreated patients with advanced/metastatic melanoma. There were no differences in the frequency of G1/G2 or G3/G4 irAEs. The choice of treatment should be based on the preferences of the patient and the clinician.

Long-Term Real-World Outcomes and Safety of Vemurafenib and Vemurafenib + Cobimetinib Therapy in Patients with BRAF-Mutated Melanoma.

BACKGROUND: Combined treatment with BRAFi and/or MEK inhibitors (MEKi) improves outcomes in advanced melanoma patients in comparison with monotherapy. OBJECTIVE: We aim to report real-world treatment efficacy and safety of vemurafenib (V) and vemurafenib + cobimetinib (V + C) from 10 years of practice. PATIENTS AND METHODS: A total of 275 consecutive patients with unresectable or metastatic BRAF mutated melanoma started first-line V or V + C treatment between 1 October 2013 and 31 December 2020. Survival analyses were performed using the Kaplan-Meier method, and Log-rank and Chi-square tests were used for comparison between groups. RESULTS: The estimated median overall survival (mOS) was 10.3 months in the V group, and 12.3 months in the V + C group (p = 0.0005; HR = 1.58, 95% CI 1.2-2.1), although the latter group of patients had lactate dehydrogenase elevated numerically more often. Estimated median progression-free survival (mPFS) was 5.5 months in the V group, and 8.3 months in the V + C group (p = 0.0002; HR = 1.62, 95% CI 1.3-2.1). Complete response, partial response, stable disease, and progressive disease as best responses were recorded in the V/V + C groups in 7%/10%, 52%/46%, 26%/28%, and 15%/16% of patients, respectively. The numbers of patients with any grade of adverse effects were similar in both groups. CONCLUSIONS: We confirmed significant improvement in the mOS and mPFS of unresectable and/or metastatic BRAF mutated-melanoma patients treated outside clinical trials with V + C as compared with V, with no major increase in toxicity for the combination.

Characteristics of Giant Nodular Melanomas in Special Locations: a Case Series and Review of the Literature.

INTRODUCTION: Nodular melanoma (NM) is a rare subtype of melanoma, responsible for more than 40% of melanoma deaths, characterized by rapid growth and high metastatic potential. Only a few case studies concerning the dermoscopic presentations of giant nodular melanoma have been reported so far. OBJECTIVES: The aim of the study was to assess dermoscopic features of giant nodular melanomas in special locations, along with their clinical and histopathologic aspects. METHODS: Among 120 patients with histopathologically confirmed melanoma treated by the Skin Cancer and Melanoma Team between September 2020 and February 2021, we identified six patients with giant nodular melanoma in special locations. We retrospectively assessed the archived dermoscopic images to determine the dermoscopic features of these tumors. RESULTS: The group consisted of six cases of giant melanoma in special locations, including the scalp (4/6) and the heel (2/6). The giant tumors were large in size (at least 5 cm in diameter). The most common dermoscopic structures in polarized light included asymmetric distribution of dermoscopic structures, the presence of structureless, multicolored zones (showing three or more colors), and the presence of white perpendicular lines or small, pink globules. CONCLUSIONS: It seems that there are no significant differences in dermoscopy between small and giant melanomas; however, further studies should be conducted on a larger scale.

Glucocorticoid-Regulated Kinase CAMKIγ in the Central Amygdala Controls Anxiety-like Behavior in Mice.

The expression of the Calcium/Calmodulin-Dependent Protein Kinase I gamma (encoded by the Camk1g gene) depends on the activation of glucocorticoid receptors (GR) and is strongly regulated by stress. Since Camk1g is primarily expressed in neuronal cells of the limbic system in the brain, we hypothesized that it could be involved in signaling mechanisms that underlie the adaptive or maladaptive responses to stress. Here, we find that restraint-induced stress and the GR agonist dexamethasone robustly increase the expression of Camk1g in neurons of the amygdalar nuclei in the mouse brain. To assess the functional role of Camk1g expression, we performed a virally induced knock-down of the transcript. Mice with bilateral amygdala-specific Camk1g knock-down showed increased anxiety-like behaviors in the light-dark box, and an increase in freezing behavior after fear-conditioning, but normal spatial working memory during exploration of a Y-maze. Thus, we confirm that Camk1g is a neuron-specific GR-regulated transcript, and show that it is specifically involved in behaviors related to anxiety, as well as responses conditioned by aversive stimuli.

Systemic treatment in patients with malignant pleural mesothelioma - real life experience.

BACKGROUND: Malignant pleural mesothelioma (MPM) is a rare, aggressive malignancy of the pleural cavity linked to asbestos exposure. The combination of pemetrexed and platinum is a standard first-line therapy for malignant pleural mesothelioma. Despite some progress, almost all MPM patients experience progression after first-line therapy. The second-line treatment is still being under discussion and there are very limited data available on the second-line and subsequent treatments. METHODS: The retrospective analysis included 57 patients (16 females and 41 males) from two Polish oncological institutions treated for advanced mesothelioma between 2013 and 2019. We analysed the efficacy of first-line and second-line therapy: progression-free survival (PFS), overall survival (OS), overall response rate (ORR). RESULTS: In the first-line treatment, 55 patients received pemetrexed-based chemotherapy (PBC) and two cisplatin in monotherapy. Patients' characteristics at baseline: median age was 64.2 years, ECOG PS ≤ 1 (86.2%), epithelial histology (85.7%). Median PFS and OS were 7.6 months and 14 months, respectively. Patients with ECOG PS ≤ 1 vs > 1 had a longer median OS (14.8 months vs 9.7 months, p = 0.057). One-year OS and PFS were 60.9% and 32.0%, respectively. Disease control rate (DCR) was 82.5%. Response to first-line therapy: PFS ≥ 6 months and PFS ≥ 12 months had a significant impact on median OS. Twelve patients received second-line therapy (seven PBC and five other cytotoxic single agents: navelbine, gemcitabine, or adriamycin/vincristine/methotrexate triplet). Median PFS and OS were 3.7 months and 7.2 months, respectively. DCR was 83%. One-year OS and PFS were 37% and 16.7%, respectively. In the group receiving PBC, OS was prolonged by 4.5 months compared to the non-PBC group (6.0 months vs 10.5 months, p = 0.47). CONCLUSION: Patients who benefited from first-line therapy and had prolonged PFS at first-line and achieve PFS longer than 6 months at first-line should be offered second-line treatment. Consideration of retreatment with the same cytotoxic agent could to be a viable option when no other treatment are available.

Treatment of Locally Advanced Merkel Cell Carcinoma-A Multi-Center Study.

Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer with a high risk of recurrence and poor prognosis. The treatment of locally advanced disease involves surgery and radiotherapy. To analyze real-life treatment patterns and clinical outcomes, we conducted a retrospective analysis of data from 161 MCC patients treated with curative intent in four oncological centers in Poland. The median age at diagnosis was 72 years (30-94); 49.7% were male. Lymph node (LN) involvement at diagnosis was found in 26.9% of patients. Sentinel lymph node biopsy (SLNB) was performed in 36.5% of patients (positive in 10.5%), and 51.9% of patients received perioperative treatment. The relapse rate was 38.3%. With the median follow-up of 2.3 years, the median disease-free survival (DFS) was not reached, and the 1-year rate was 65%. The negative independent risk factors for DFS were male gender, metastases in LN at diagnosis, no SLNB in patients without clinical nodal metastases, and no perioperative radiotherapy. The estimated median overall survival (OS) was 6.9 years (95% CI 4.64-9.15). The negative independent risk factors for OS were male gender, age above 70, metastases in LN at diagnosis, and no SLNB in patients without clinical nodal metastases. Our results confirm that the MCC treatment should be conducted in an experienced multidisciplinary team; however, the outcomes are still unsatisfactory.

Development of immunity-related adverse events correlates with baseline clinical factors, survival and response to anti-PD-1 treatment in patients with inoperable or metastatic melanoma.

BACKGROUND: The relationship between immune related adverse events (irAEs) and efficacy is not definitively proven, and data on the relationship between irAE and treatment efficacy are contradictory. MATERIAL AND METHODS: Five hundred ninety-three consecutive patients with unresectable or metastatic melanoma treated in the first line with anti-PD-1 (nivolumab or pembrolizumab) between January 2016 and December 2019 were enrolled in the study. RESULTS: Statistically significant differences were demonstrated between the group of patients without and with irAE in median OS and PFS (p < .0001 both) and also in OS between the group of patients without irAE and patients with irAE within 3, 6, and 9 months from the start of anti-PD-1 therapy (p = .0121, p = .0014, p < .0001; respectively) and PFS (p = .0369, p = .0052, p = .0001; respectively). A statistically significant relationship was demonstrated between the occurrence of irAE and the location of the primary tumor (skin vs. mucosa vs. unknown; p = .0183), brain metastasis (present vs. absent; p = .0032), other locations (present vs. absent, p = .0032), LDH (normal vs. elevated; p = .0046) and stage according to TNM (p = .0093). CONCLUSION: The occurrence of irAE was associated with longer OS, PFS, and more frequent response to treatment. IrAE occurred statistically significantly more often in patients with mucosa primary tumor, with normal LDH levels, without brain metastases, stages III, M1a, and M1b.

The Role of Mesostriatal Dopamine System and Corticostriatal Glutamatergic Transmission in Chronic Pain.

There is increasing recognition of the involvement of the nigrostriatal and mesolimbic dopamine systems in the modulation of chronic pain. The first part of the present article reviews the evidence indicating that dopamine exerts analgesic effects during persistent pain by stimulating the D2 receptors in the dorsal striatum and nucleus accumbens (NAc). Thereby, dopamine inhibits striatal output via the D2 receptor-expressing medium spiny neurons (D2-MSN). Dopaminergic neurotransmission in the mesostriatal pathways is hampered in chronic pain states and this alteration maintains and exacerbates pain. The second part of this article focuses on the glutamatergic inputs from the medial prefrontal cortex to the NAc, their activity changes in chronic pain, and their role in pain modulation. Finally, interactions between dopaminergic and glutamatergic inputs to the D2-MSN are considered in the context of persistent pain. Studies using novel techniques indicate that pain is regulated oppositely by two independent dopaminergic circuits linking separate parts of the ventral tegmental area and of the NAc, which also interact with distinct regions of the medial prefrontal cortex.

Assessment of hormonal levels as prognostic markers and of their optimal cut-offs in small intestinal neuroendocrine tumours grade 2.

PURPOSE: Small intestinal neuroendocrine tumours (siNETs) with a Ki-67 proliferation index between 3 and 20% belong to WHO grade 2. Response to treatment may be monitored by blood chromogranin A (CgA) and urine 5-hydroxyindoleacetic acid (5HIAA). The aim of this retrospective study was to investigate the prognostic value of baseline CgA and 5HIAA and of the early biochemical response to treatment, and to compare different cut-off values used in the literature. METHODS: A retrospective cohort study of 184 patients with siNET Grade 2 treated with somatostatin analogues (SSA), interferon-alpha (IFN) or peptide receptor radionuclide therapy (PRRT). RESULTS: Baseline CgA was a statistically significant prognostic marker for both cancer-specific survival (CSS) and progression-free survival (PFS). A cut-off of 5 × ULN (upper limit of normal) was best discriminative in most cases, but 2 × ULN discriminated better for SSA. Baseline 5HIAA was a prognostic marker for CSS in treatment with IFN and PRRT, but not for single SSA. Early changes of CgA and 5HIAA correlated well with CSS (HR 3.18, 95% CI 1.82-5.56 and HR 1.47, 95% CI 1.16-1.86) and PFS (HR 3.08, 95% CI 1.86-5.10 and HR 1.37, 95% CI 1.11-1.68) for SSA, but not for PRRT. CONCLUSIONS: Baseline CgA and to a lesser extent 5HIAA are associated with CSS irrespective of treatment used, and with PFS after PRRT, and 5 × ULN provides best discrimination in many, but not all, cases. Early reductions of CgA and 5HIAA are prognostic for treatment with SSA, but not PRRT.

First-line treatment of advanced/metastatic melanoma with anti-PD-1 antibodies: multicenter experience in Poland.

Aim: To evaluate treatment results in advanced/metastatic melanoma patients treated with anti-PD-1 immunotherapy in routine practice in oncology centers in Poland. Methods: Multicenter retrospective analysis included 499 patients with unresectable/metastatic (stage IIIC-IV) melanoma treated with anti-PD-1 in first-line therapy. Results: Estimated median overall survival (OS) and progression-free survival (PFS) were 19.9 and 7.9 months, respectively. Multivariate analysis confirmed that ECOG 0, no brain metastases, normal lactate dehydrogenase level and occurrence of immune-related adverse events (irAEs) were statistically significantly associated with improved OS and PFS. Any irAE occurred in 24% of patients. Grade 3 or Grade 4 irAEs occurred in 6% of patients. Conclusion: Analysis revealed a slightly worse OS in real-world treatment in comparison to clinical trials (KEYNOTE-006 and CheckMate 066). Polish population treatment results are similar to other studies of real-world data. PFS and ORR are similar in our research and clinical trials.

Anti-programmed cell death-1 therapy in octogenarian and nonagenarian advanced/metastatic melanoma patients.

Immunotherapy with anti-programmed cell death-1 (PD-1) agents is an effective treatment for metastatic melanoma. Octogenarians and nonagenarians represent a significant cohort of melanoma patients. This multicenter retrospective analysis enrolled 499 patients treated with nivolumab or pembrolizumab. Seventy-three patients were aged 80-100, 218 patients were aged 65-79, and 208 patients were <65 years old. Baseline parameters were comparable. The median overall survival (OS) was 14.7, 18.7, 25.9, and the median progression-free survival (PFS) was 8.7, 7.7, and 6.2 months in the age groups of 80-100, 65-79, and <65 years, respectively. The median melanoma-specific survival (MSS) was 22.5, 27.8, and 31.6 months in the age groups of 80-100, 65-79, and <65 years, respectively. There was no statistically significant difference in OS (P = 0.2897), PFS (P = 0.7155), and MSS (P = 0.9235) between the group of 80-100 years old vs. 65-79 and vs. <65 years old patients. Overall response rate and disease control rate was similar in all groups (P = 0.06974 and P = 0.89435, respectively). Overall, the immune-related adverse event (irAE) rate was comparable in the three age groups (41, 34, and 37.5% in the groups of patients aged 80-100, 65-79, and <65 years, respectively). Also, the rates of G3 and G4 irAEs were comparable (4, 6, and 7% in the groups of patients, respectively). The efficacy and toxicity of anti-PD-1 therapy in octogenarians and nonagenarians with metastatic melanoma are similar as in patients aged <65 years and 65-79 years. The patients' age should not be considered as an exclusion criterion for anti-PD-1 treatment.

Neuropathic Pain Dysregulates Gene Expression of the Forebrain Opioid and Dopamine Systems.

Disturbances in the function of the mesostriatal dopamine system may contribute to the development and maintenance of chronic pain, including its sensory and emotional/cognitive aspects. In the present study, we assessed the influence of chronic constriction injury (CCI) of the sciatic nerve on the expression of genes coding for dopamine and opioid receptors as well as opioid propeptides in the mouse mesostriatal system, particularly in the nucleus accumbens. We demonstrated bilateral increases in mRNA levels of the dopamine D1 and D2 receptors (the latter accompanied by elevated protein level), opioid propeptides proenkephalin and prodynorphin, as well as delta and kappa (but not mu) opioid receptors in the nucleus accumbens at 7 to 14 days after CCI. These results show that CCI-induced neuropathic pain is accompanied by a major transcriptional dysregulation of molecules involved in dopaminergic and opioidergic signaling in the striatum/nucleus accumbens. Possible functional consequences of these changes include opposite effects of upregulated enkephalin/delta opioid receptor signaling vs. dynorphin/kappa opioid receptor signaling, with the former most likely having an analgesic effect and the latter exacerbating pain and contributing to pain-related negative emotional states.

Predictive value of quantitative HER2, HER3 and p95HER2 levels in HER2-positive advanced breast cancer patients treated with lapatinib following progression on trastuzumab.

Lapatinib is a HER1 and HER2 tyrosine kinase inhibitor (TKI) approved in second line treatment of advanced or metastatic breast cancer following progression on trastuzumab-containing therapy. Biomarkers for activity of lapatinib and other TKIs are lacking. Formalin-fixed, paraffin-embedded primary tumor samples were obtained from 189 HER2-positive patients treated with lapatinib plus capecitabine following progression on trastuzumab. The HERmark® Breast Cancer Assay was used to quantify HER2 protein expression. HER3 and p95HER2 protein expression was quantified using the VeraTag® technology. Overall survival (OS) was inversely correlated with HER2 (HR = 1.9/log; P = 0.009) for patients with tumors above the cut-off positivity level by the HERmark assay. OS was significantly shorter for those with above median HER2 levels (HR = 1.7; P = 0.015) and trended shorter for those below the cut-off level of positivity by the HERmark assay (HR = 1.7; P = 0.057) compared to cases with moderate HER2 overexpression. The relationship between HER2 protein expression and OS was best captured with a U-shaped parabolic function (P = 0.004), with the best prognosis at moderate levels of HER2 protein overexpression. In a multivariate model including HER2, increasing p95HER2 expression was associated with longer OS (HR = 0.35/log; P = 0.027). Continuous HER3 did not significantly correlate with OS. Patients with moderately overexpressed HER2 levels and high p95HER2 expression may have best outcomes while receiving lapatinib following progression on trastuzumab. Further study is warranted to explore the predictive utility of quantitative HER2 and p95HER2 in guiding HER2-directed therapies.

Co-expression of autophagic markers following photodynamic therapy in SW620 human colon adenocarcinoma cells.

Photodynamic therapy (PDT) is a minimally invasive cancer treatment. It involves the combination of a photosensitizer and light of a specific wavelength to generate singlet oxygen and other reactive oxygen species that lead to tumor cell death. Autophagy is one of the pathways that tumor cells undergo during photodamage and it is common in photodynamic therapy. The aim of this study was to examine the effect of in vitro PDT on the expression of autophagy­related proteins, autophagy related 7 (Atg7), light chain 3 (LC3) and Beclin­1. Human SW620 colon carcinoma cells were treated with 5-aminolevulinic acid (ALA)­based PDT at a dose of 3 mM. The irradiation was performed using 4.5 J/cm2 total light and a fluence rate of 60 mW/cm2. Autophagy was evaluated by immunocytochemistry using specific antibodies to Atg7, Beclin­1 and LC3. The evaluation was repeated at several time points (0, 4, 8 and 24 h) following irradiation. The induction of autophagy was observed directly following the 5­ALA­mediated PDT procedure with the strongest expression of autophagy-related proteins at 4 and 8 h after irradiation as demonstrated using immunocytochemistry. It was characterized by significantly increased expression of Beclin­1, Atg7 and LC3. To the best of our knowledge this is the first study to analyze Beclin­1, Atg7 and LC3 expression in a PDT­related experiment. This study enhances the understanding of the role of autophagy in PDT, which may contribute to better and more effective tumor responses to this therapy.

Immunohistochemical prediction of lapatinib efficacy in advanced HER2-positive breast cancer patients.

UNLABELLED: Molecular mechanisms of lapatinib resistance in breast cancer are not well understood. The aim of this study was to correlate expression of selected proteins involved in ErbB family signaling pathways with clinical efficacy of lapatinib. Study group included 270 HER2-positive advanced breast cancer patients treated with lapatinib and capecitabine. Immunohistochemical expression of phosphorylated adenosine monophosphate-activated protein (p-AMPK), mitogen-activated protein kinase (p-MAPK), phospho (p)-p70S6K, cyclin E, phosphatase and tensin homolog were analyzed in primary breast cancer samples. The best discriminative value for progression-free survival (PFS) was established for each biomarker and subjected to multivariate analysis. At least one biomarker was determined in 199 patients. Expression of p-p70S6K was independently associated with longer (HR 0.45; 95% CI: 0.25-0.81; p = 0.009), and cyclin E with shorter PFS (HR 1.83; 95% CI: 1.06-3.14; p = 0.029). Expression of p-MAPK (HR 1.61; 95% CI 1.13-2.29; p = 0.009) and cyclin E (HR 2.99; 95% CI: 1.29-6.94; p = 0.011) was correlated with shorter, and expression of estrogen receptor (HR 0.65; 95% CI 0.43-0.98; p = 0.041) with longer overall survival. Expression of p-AMPK negatively impacted response to treatment (HR 3.31; 95% CI 1.48-7.44; p = 0.004) and disease control (HR 3.07; 95% CI 1.25-7.58; p = 0.015). IN CONCLUSION: the efficacy of lapatinib seems to be associated with the activity of downstream signaling pathways - AMPK/mTOR and Ras/Raf/MAPK. Further research is warranted to assess the clinical utility of these data and to determine a potential role of combining lapatinib with MAPK pathway inhibitors.

Novel drug-regulated transcriptional networks in brain reveal pharmacological properties of psychotropic drugs.

BACKGROUND: Despite their widespread use, the biological mechanisms underlying the efficacy of psychotropic drugs are still incompletely known; improved understanding of these is essential for development of novel more effective drugs and rational design of therapy. Given the large number of psychotropic drugs available and their differential pharmacological effects, it would be important to establish specific predictors of response to various classes of drugs. RESULTS: To identify the molecular mechanisms that may initiate therapeutic effects, whole-genome expression profiling (using 324 Illumina Mouse WG-6 microarrays) of drug-induced alterations in the mouse brain was undertaken, with a focus on the time-course (1, 2, 4 and 8 h) of gene expression changes produced by eighteen major psychotropic drugs: antidepressants, antipsychotics, anxiolytics, psychostimulants and opioids. The resulting database is freely accessible at http://www.genes2mind.org. Bioinformatics approaches led to the identification of three main drug-responsive genomic networks and indicated neurobiological pathways that mediate the alterations in transcription. Each tested psychotropic drug was characterized by a unique gene network expression profile related to its neuropharmacological properties. Functional links that connect expression of the networks to the development of neuronal adaptations (MAPK signaling pathway), control of brain metabolism (adipocytokine pathway), and organization of cell projections (mTOR pathway) were found. CONCLUSIONS: The comparison of gene expression alterations between various drugs opened a new means to classify the different psychoactive compounds and to predict their cellular targets; this is well exemplified in the case of tianeptine, an antidepressant with unknown mechanisms of action. This work represents the first proof-of-concept study of a molecular classification of psychoactive drugs.

Effects of morphine on immediate-early gene expression in the striatum of C57BL/6J and DBA/2J mice.

BACKGROUND: Immediate early gene (IEG) induction elicited by drugs of abuse may contribute to development of plastic changes in the brain responsible for drug-induced behavioral changes leading to addiction. The aim of the present study was to characterize the changes in IEG expression in the striatum and nucleus accumbens produced by an acute or chronic administration of morphine. METHODS: In order to search for a possible relationship between morphine-induced IEG expression and behavior, the experiment was performed on two inbred strains of mice, C57BL/6J and DBA/2J, which differ markedly in their sensitivity to the rewarding and locomotor stimulatory actions of opiates. Gene expression was assessed using RT-PCR and DNA microarrays. RESULTS: The experiments demonstrated a prolonged or a delayed up-regulation of 14 IEG in the striatum at 4 h after morphine administration. Among them, a cluster of 8 genes, including 6 inducible transcription factors (c-fos, fra-2, junB, zif268 (egr1), egr2, NGFI-B) and 2 effector IEG (arc and mkp1) seemed to be regulated in concert in response to morphine. This group of genes was induced to a greater degree after chronic than acute morphine administration selectively in C57BL/6J mice and the difference bore apparently no relationship to opiate-produced locomotor activation. The strain-selective regulation was also demonstrated for cyclin L2 and tPA after an acute morphine injection. CONCLUSIONS: Our data indicate that morphine up-regulates many IEG in the mouse striatum at a strikingly delayed time-point and that these changes are genotype-dependent. They also suggest inter-strain differences in the development of striatal neuroadaptations to chronic morphine treatment.

Regulation of the immediate-early genes arc and zif268 in a mouse operant model of cocaine seeking reinstatement.

Reinstatement of extinguished operant responding for drug is an appropriate model of relapse to drug abuse. Due to the difficulty of implementing in mice the procedure of instrumental intravenous self-administration, mechanisms of reinstatement have so far been studied almost exclusively in rats. A mouse model of reinstatement of cocaine seeking has recently been characterized (Soria et al. 2008). The aim of the present study was to assess regional brain activation, as measured by induction of the immediate early genes (IEG) arc and zif268, during priming- or cue-elicited reinstatement of cocaine seeking using this new mouse model and the in situ hybridization technique. We have demonstrated that cue-elicited reinstatement of cocaine seeking was associated with induction of the IEG in the medial prefrontal cortex (prelimbic and infralimbic) and basolateral amygdala. Priming-induced reinstatement produced a more widespread up-regulation of those genes in forebrain regions including medial prefrontal, orbitofrontal and motor cortex, dorsal striatum and basolateral amygdala. These patterns of IEG expression are in agreement with previous results obtained in rats and thus indicate that the new mouse model of reinstatement is functionally equivalent to rat models. That comparability adds to the usefulness of the mouse model as a tool for addressing neurobiological mechanisms of addiction.

New operant model of reinstatement of food-seeking behavior in mice.

RATIONALE: A major problem in treating obesity is the high rate of relapse to abnormal food-taking behavior when maintaining diet. OBJECTIVES: The present study evaluates the reinstatement of extinguished palatable food-seeking behavior induced by cues previously associated with the palatable food, re-exposure to this food, or stress. The participation of the opioid and dopamine mechanisms in the acquisition, extinction, and cue-induced reinstatement was also investigated. MATERIALS AND METHODS: C57BL/6 mice were first trained on a fixed-ratio-1 schedule of reinforcement to obtain chocolate-flavored pellets during 20 days, which was associated to a stimulus light. Operant behavior was then extinguished during 20 daily sessions. mRNA levels of opioid peptide precursors and dopamine receptors were evaluated in the brain by in situ hybridization and RT-PCR techniques. RESULTS: A reinstatement of food-seeking behavior was only obtained after exposure to the food-associated cue. A down-regulation of prodynorphin mRNA was found in the dorsal striatum and nucleus accumbens after the acquisition, extinction, and reinstatement of the operant behavior. Extinction and reinstatement of this operant response enhanced proenkephalin mRNA in the dorsal striatum and/or the nucleus accumbens core. Down-regulation of D2 receptor expression was observed in the dorsal striatum and nucleus accumbens after reinstatement. An up-regulation of PDYN mRNA expression was found in the hypothalamus after extinction and reinstatement. CONCLUSIONS: This study provides a new operant model in mice for the evaluation of food-taking behavior and reveals specific changes in the dopamine and opioid system associated to the behavioral responses directed to obtain a natural reward.

The dissection of transcriptional modules regulated by various drugs of abuse in the mouse striatum.

BACKGROUND: Various drugs of abuse activate intracellular pathways in the brain reward system. These pathways regulate the expression of genes that are essential to the development of addiction. To reveal genes common and distinct for different classes of drugs of abuse, we compared the effects of nicotine, ethanol, cocaine, morphine, heroin and methamphetamine on gene expression profiles in the mouse striatum. RESULTS: We applied whole-genome microarray profiling to evaluate detailed time-courses (1, 2, 4 and 8 hours) of transcriptome alterations following acute drug administration in mice. We identified 42 drug-responsive genes that were segregated into two main transcriptional modules. The first module consisted of activity-dependent transcripts (including Fos and Npas4), which are induced by psychostimulants and opioids. The second group of genes (including Fkbp5 and S3-12), which are controlled, in part, by the release of steroid hormones, was strongly activated by ethanol and opioids. Using pharmacological tools, we were able to inhibit the induction of particular modules of drug-related genomic profiles. We selected a subset of genes for validation by in situ hybridization and quantitative PCR. We also showed that knockdown of the drug-responsive genes Sgk1 and Tsc22d3 resulted in alterations to dendritic spines in mice, possibly reflecting an altered potential for plastic changes. CONCLUSIONS: Our study identified modules of drug-induced genes that share functional relationships. These genes may play a critical role in the early stages of addiction.