Faculty Bibliography

Cancer patients in pain require high doses of opioids and quickly become opioid-tolerant. Previous studies have shown that both chronic cancer pain and high dose opioid use lead to mu-opioid receptor down-regulation. In this study we explore down-regulation of OPRM1, the mu-opioid receptor gene, as a mechanism f,or opioid tolerance in the setting of opioid use for cancer pain. We demonstrate in a cohort of 84 cancer patients that high dose opioid use correlates with OPRM1 hypermethylation in peripheral leukocytes of these patients. We then reverse-translate our clinical findings by creating a mouse cancer pain model; we create opioid tolerance in the mouse cancer model to mimic opioid tolerance in the cancer patients. Using this model we determine the functional significance of OPRM1 methylation on cancer pain and opioid tolerance. We focus on two main cells within the cancer microenvironment: the cancer cell and the neuron. We show that targeted re-expression of mu-opioid receptor on cancer cells inhibits mechanical and thermal hypersensitivity, and prevents opioid tolerance, in the mouse model. The resultant analgesia and protection against opioid tolerance are likely due to preservation of mu-opioid receptor expression on the cancer-associated neurons.

We propose a new mechanism of sensory modulation through cutaneous dopaminergic signalling. We hypothesize that dopaminergic signalling contributes to differential cutaneous sensitivity in darker versus lighter pigmented humans and mouse strains. We show that thermal and mechanical cutaneous sensitivity is pigmentation dependent. Meta-analyses in humans and mice, along with our own mouse behavioural studies, reveal higher thermal sensitivity in pigmented skin relative to less-pigmented or albino skin. We show that dopamine from melanocytes activates the D1-like dopamine receptor on primary sensory neurons. Dopaminergic activation increases expression of the heat-sensitive TRPV1 ion channel and reduces expression of the mechanically-sensitive Piezo2 channel; thermal threshold is lower and mechanical threshold is higher in pigmented skin.

Background: In this study, we developed integrative, personalized prognostic models for breast cancer recurrence and overall survival (OS) that consider receptor subtypes, epidemiological data, quality of life (QoL), and treatment. Methods: 15,314 women with stage I to III invasive primary breast cancer treated at The University of Texas MD Anderson Cancer Center between 1997 and 2012 was used to generate prognostic models by Cox regression analysis including 10,809 women as discovery population (median follow-up: 6.09 years, 1,144 recurrence and 1,627 deaths) and 4,505 women as validation population (median follow-up: 7.95 years, 684 recurrence and 1,095 deaths). Model performance was assessed by calculating the area under the curve (AUC) and calibration analysis and compared with Nottingham Prognostic Index (NPI) and PREDICT. Results: In addition to the known clinical/pathological variables, the model for recurrence included alcohol consumption while the model for OS included smoking status and physical component summary score. The AUCs for recurrence and OS were 0.813 and 0.810 in the discovery and 0.807 and 0.803 in the validation, respectively, compared to AUC of 0.761 and 0.753 in discovery and 0.777 and 0.751 in validation for NPI. Our model further showed better calibration compared to PREDICT. We also developed race-specific and receptor subtype-specific models with comparable AUC. Racial disparity was evident in the distributions of many risk factors and clinical presentation of the disease. Conclusions: Our integrative prognostic models for breast cancer exhibit high discriminatory accuracy and excellent calibration and are the first to incorporate receptor subtype, epidemiological and QoL data

BACKGROUND: In order to generate valid results in RCTs, it is important to collect unbiased data. Behavioral intervention trials are more difficult to blind than pharmacologic trials. In our ongoing behavioral trial, PATRIOT, which aims to prevent foot complications in diabetes through improved self-care, we are intervening both face-to-face as well as remotely. Consequently blinding is more difficult. Here we illustrate the different blinding processes used. METHODS: In the PATRIOT trial, following randomization during the baseline visit, the intervention group receives computer-based education and demonstration on how to use a special foot thermometer. Following that, intervention participants receive a comprehensive intervention that includes regular telephone counseling and tailored mailings. The control group receives health prevention strategies not related to foot care. For this complex intervention, we needed to develop new strategies to maintain blinding at the participant, research assistant (RA), counselor, outcome adjudicator and data analyst levels. We created a "Blinding Tracker" to identify unblinded and blinded staff so that participants pass from unblinded to blinded staff so that only blinded staff collect data. The integrity of the study is maintained by careful monitoring of blinding with any break in blinding being contained. RESULTS: To date, we have enrolled 221 participants. While participants know the arm to which they are randomized, we needed to make sure that the staff collecting data are blinded. Participants are educated throughout the whole study process by the telephone counselors about the importance of blinding using non-scientific descriptions. Though the counselors know their participant's treatment assignment, they do not know their foot photography results and other outcomes. The RA's, who conduct study visits and collect data, are blinded to treatment assignment. To improve efficiency and preserve blinding, we have different RAs for different phases of a participant's progress. Initially, RAs are initially blinded, but by the end of their involvement with a particular subject, when data collection is done, they become unblinded so they can show the educational videos and demonstrate foot thermometer use. However, RA's can also become unblinded prematurely. To date, out of 96 six-month visits, there have been 26 such instances. RAs are subsequently transitioned off a particular subject to be replaced by a blinded RA. We will also control for RA blinding in the analysis. The adjudicators who read the foot photographs to determine outcomes and the statisticians are blinded to treatment assignment. CONCLUSIONS: Novel techniques have been used to achieve and maintain blinding, but it is resource intensive. While conducting complex trials, vigilance and responsiveness are needed. Finally, blinding information should be incorporated in the analysis in order to get the most valid results

Virus-mediated gene delivery shows promise for the treatment of chronic pain. However, viral vectors have cytotoxicity. To avoid toxicities and limitations of virus-mediated gene delivery, we developed a novel nonviral hybrid vector: HIV-1 Tat peptide sequence modified with histidine and cysteine residues combined with a cationic lipid. The vector has high transfection efficiency with little cytotoxicity in cancer cell lines including HSC-3 (human tongue squamous cell carcinoma) and exhibits differential expression in HSC-3 ( approximately 45-fold) relative to HGF-1 (human gingival fibroblasts) cells. We used the nonviral vector to transfect cancer with OPRM1, the mu-opioid receptor gene, as a novel method for treating cancer-induced pain. After HSC-3 cells were transfected with OPRM1, a cancer mouse model was created by inoculating the transfected HSC-3 cells into the hind paw or tongue of athymic mice to determine the analgesic potential of OPRM1 transfection. Mice with HSC-3 tumors expressing OPRM1 demonstrated significant antinociception compared with control mice. The effect was reversible with local naloxone administration. We quantified beta-endorphin secretion from HSC-3 cells and showed that HSC-3 cells transfected with OPRM1 secreted significantly more beta-endorphin than control HSC-3 cells. These findings indicate that nonviral delivery of the OPRM1 gene targeted to the cancer microenvironment has an analgesic effect in a preclinical cancer model, and nonviral gene delivery is a potential treatment for cancer pain.

Purpose: Oral squamous cell carcinoma (SCC) invasion and metastasis result in treatment failure and correlate with increased pain. We have previously shown that the "endothelin axis," consisting of endothelin A and B receptors (ETAR and ETBR), mediates oral SCC pain, and that inhibiting ETAR with macitentan alleviates pain. We now hypothesize that the endothelin axis also mediates oral SCC growth and metastasis. We explore the therapeutic effect of concurrent ETAR antagonism (with macitentan) and ETBR re-expression on oral SCC growth and invasion in vitro and in vivo. Methods: We quantified the effect of macitentan treatment and targeted ETBR re-expression on oral SCC cell invasion and proliferation, in vitro indices of metastasis and growth, using a Matrigel invasion chamber assay and the Real Time Cell Analyzer (RTCA). We then created an oral SCC mouse model to determine the effect of macitentan treatment on oral SCC growth. Results: Macitentan treatment or ETBR re-expression alone significantly inhibited oral SCC proliferation and invasion in a dose-dependent manner; macitentan combined with ETBR re-expression had the strongest inhibitory effect on cancer proliferation and invasion. In the oral SCC mouse model, macitentan treatment and ETBR re-expression had significant anti-proliferative and anti-metastatic effects compared to control treatment. Conclusion: Our strategy of targeting the endothelin axis inhibited cancer growth and invasion in vitro and in a preclinical model. These results establish the therapeutic potential of macitentan, an orally available ETAR antagonist, for oral SCC metastasis

Orofacial pain may be a symptom of diverse types of cancers as a result of local or distant tumor effects. The pain can be presented with the same characteristics as any other orofacial pain disorder, and this should be recognized by the clinician. Orofacial pain also can arise as a consequence of cancer therapy. In the present article, we review the mechanisms of cancer-associated facial pain, its clinical presentation, and cancer therapy associated with orofacial pain.

Differential thermal nociception across inbred mouse strains has genetic determinants. Thermal nociception is largely attributed to the heat/capsaicin receptor TRPV1; however, the contribution of this channel to the genetics of thermal nociception has not been revealed. In this study we compared TRPV1 expression levels and electrophysiological properties in primary sensory neurons and thermal nociceptive behaviors between two (C57BL/6 and BALB/c) inbred mouse strains. Using immunofluorescence and patch-clamp physiology methods, we demonstrated that TRPV1 expression was significantly higher in isolectin B4 (IB4) -positive trigeminal sensory neurons of C57BL/6 relative to BALB/c; the expression in IB4-negative neurons was similar between the strains. Furthermore, using electrophysiological cell classification (current signature method), we showed differences between the two strains in capsaicin sensitivity in IB4-positive neuronal cell types 2 and 13, that were previously reported as skin nociceptors. Otherwise electrophysiological membrane properties of the classified cell types were similar in the two mouse strains. In publicly available nocifensive behavior data and our own behavior data from the using the two mouse strains, C57BL/6 exhibited higher sensitivity to heat stimulation than BALB/c, independent of sex and anatomical location of thermal testing (the tail, hind paw and whisker pad). The TRPV1 selective antagonist JNJ-17203212 inhibited thermal nociception in both strains; however, removing IB4-positive trigeminal sensory neurons with IB4-conjugated saporin inhibited thermal nociception on the whisker pad in C57BL/6, but not in BALB/c. These results suggest that TRPV1 expression levels in IB4-positive type 2 and 13 neurons contributed to differential thermal nociception in skin of C57BL/6 compared to BALB/c.