Local irradiation in combination with bevacizumab enhances radiation control of bone destruction and cancer-induced pain in a model of bone metastases

The integration of radiotherapy with systemic therapy in advanced triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, with high aggressiveness and poor prognosis. For patients who have undergone multiple treatments, systemic drug therapy often presents challenges with limited efficacy and significant side effects. Radiotherapy, a pivotal local treatment, has shown substantial local control benefits in patients with inoperable locally advanced or metastatic disease. Clinical evidence suggests that integrating systemic therapy with locoregional radiotherapy can confer survival advantages in advanced malignancies. Within multidisciplinary treatment, the synergy between radiotherapy and systemic therapies shows promise for enhancing outcomes and extending survival. This review synthesizes recent advances in combining radiotherapy and systemic therapy in managing advanced TNBC, focusing on preclinical and clinical evidence regarding efficacy and safety. By reviewing these advancements, we aim to identify novel therapeutic strategies and integrate clinical evidence to inform best practices in TNBC management, ultimately improving patient outcomes.

Electrical stimulation affects the differentiation of transplanted regionally specific human spinal neural progenitor cells (sNPCs) after chronic spinal cord injury

BACKGROUND

There are currently no effective clinical therapies to ameliorate the loss of function that occurs after spinal cord injury. Electrical stimulation of the rat spinal cord through the rat tail has previously been described by our laboratory. We propose combinatorial treatment with human induced pluripotent stem cell-derived spinal neural progenitor cells (sNPCs) along with tail nerve electrical stimulation (TANES). The purpose of this study was to examine the influence of TANES on the differentiation of sNPCs with the hypothesis that the addition of TANES would affect incorporation of sNPCs into the injured spinal cord, which is our ultimate goal.

METHODS

Chronically injured athymic nude rats were allocated to one of three treatment groups: injury only, sNPC only, or sNPC + TANES. Rats were sacrificed at 16 weeks post-transplantation, and tissue was processed and analyzed utilizing standard histological and tissue clearing techniques. Functional testing was performed. All quantitative data were presented as mean ± standard error of the mean. Statistics were conducted using GraphPad Prism.

RESULTS

We found that sNPCs were multi-potent and retained the ability to differentiate into mainly neurons or oligodendrocytes after this transplantation paradigm. The addition of TANES resulted in more transplanted cells differentiating into oligodendrocytes compared with no TANES treatment, and more myelin was found. TANES not only promoted significantly higher numbers of sNPCs migrating away from the site of injection but also influenced long-distance axonal/dendritic projections especially in the rostral direction. Further, we observed localization of synaptophysin on SC121-positive cells, suggesting integration with host or surrounding neurons, and this finding was enhanced when TANES was applied. Also, rats that were transplanted with sNPCs in combination with TANES resulted in an increase in serotonergic fibers in the lumbar region. This suggests that TANES contributes to integration of sNPCs, as well as activity-dependent oligodendrocyte and myelin remodeling of the chronically injured spinal cord.

CONCLUSIONS

Together, the data suggest that the added electrical stimulation promoted cellular integration and influenced the fate of human induced pluripotent stem cell-derived sNPCs transplanted into the injured spinal cord.

miR-199a-3p suppresses neuroinflammation by directly targeting MyD88 in a mouse model of bone cancer pain

AIMS

Pain is a profoundly debilitating symptom in cancer patients, leading to disability, immobility, and a marked decline in their quality of life. This study aimed to investigate the potential roles of miR-199a-3p in a murine model of bone cancer pain induced by tumor cell implantation in the medullary cavity of the femur.

MATERIALS AND METHODS

We assessed pain-related behaviors, including the paw withdrawal mechanical threshold (PWMT) and the number of spontaneous flinches (NSF). To investigate miRNA expression and its targets in astrocytes, we employed a combination of RNA-seq analysis, qRT-PCR, Western blotting, EdU, TUNEL, ChIP, ELISA, and luciferase reporter assays in mice (C3H/HeJ) with bone cancer pain and control groups.

KEY FINDINGS

On days 10, 14, 21, and 28 post-surgery, we observed significant differences in PWTL, PWMT, and NSF when compared to the sham group (P < 0.001). qRT-PCR assays and miRNA sequencing results confirmed reduced miR-199a-3p expression in astrocytes of mice with bone cancer pain. Gain- and loss-of-function experiments demonstrated that miR-199a-3p suppressed astrocyte activation and the expression of inflammatory cytokines. In vitro investigations revealed that miR-199a-3p mimics reduced the levels of inflammatory factors in astrocytes and MyD88/NF-κB proteins. Furthermore, treatment with a miR-199a-3p agonist resulted in reduced expression of MyD88, TAK1, p-p65, and inflammatory mediators, along with decreased astrocyte activation in the spinal cord.

SIGNIFICANCE

Collectively, these findings demonstrate that upregulation of miR-199a-3p may offer a therapeutic avenue for mitigating bone cancer pain in mice by suppressing neuroinflammation and inhibiting the MyD88/NF-κB signaling pathway.

Safety and Efficacy of Rose Bengal Derivatives for Glial Scar Ablation in Chronic Spinal Cord Injury

There are no effective therapies available currently to ameliorate loss of function for patients with spinal cord injuries (SCIs). In addition, proposed treatments that demonstrated functional recovery in animal models of acute SCI have failed almost invariably when applied to chronic injury models. Glial scar formation in chronic injury is a likely contributor to limitation on regeneration. We have removed existing scar tissue in chronically contused rat spinal cord using a rose Bengal-based photo ablation approach. In this study, we compared two chemically modified rose bengal derivatives to unmodified rose bengal, both confirming and expanding on our previously published report. Rats were treated with unmodified rose bengal (RB1) or rose bengal modified with hydrocarbon (RB2) or polyethylene glycol (RB3), to determine the effects on scar components and spared tissue post-treatment. Our results showed that RB1 was more efficacious than RB2, while still maintaining minimal collateral effects on spared tissue. RB3 was not taken up by the cells, likely because of its size, and therefore had no effect. Treatment with RB1 also resulted in an increase in serotonin eight days post-treatment in chronically injured spinal cords. Thus, we suggest that unmodified rose Bengal is a potent candidate agent for the development of a therapeutic strategy for scar ablation in chronic SCI.

The Impact of Radiation on the Tumor Microenvironment: Effect of Dose and Fractionation Schedules

In addition to inducing lethal DNA damage in tumor and stromal cells, radiation can alter the interactions of tumor cells with their microenvironment. Recent technological advances in planning and delivery of external beam radiotherapy have allowed delivery of larger doses per fraction (hypofractionation) while minimizing dose to normal tissues with higher precision. The effects of radiation on the tumor microenvironment vary with dose and fractionation schedule. In this review, we summarize the effects of conventional and hypofractionated radiation regimens on the immune system and tumor stroma. We discuss how these interactions may provide therapeutic benefit in combination with targeted therapies. Understanding the differential effects of radiation dose and fractionation can have implications for choice of combination therapies.

Topical Treatment with Xiaozheng Zhitong Paste (XZP) Alleviates Bone Destruction and Bone Cancer Pain in a Rat Model of Prostate Cancer-Induced Bone Pain by Modulating the RANKL/RANK/OPG Signaling

To explore the effects and mechanisms of Xiaozheng Zhitong Paste (XZP) on bone cancer pain, Wistar rats were inoculated with vehicle or prostate cancer PC-3 into the tibia bone and treated topically with inert paste, XZP at 15.75, 31.5, or 63 g/kg twice per day for 21 days. Their bone structural damage, nociceptive behaviors, bone osteoclast and osteoblast activity, and the levels of OPG, RANL, RNAK, PTHrP, IGF-1, M-CSF, IL-8, and TNF-α were examined. In comparison with that in the placebo group, significantly reduced numbers of invaded cancer cells, decreased levels of bone damage and mechanical threshold and paw withdrawal latency, lower levels of serum TRACP5b, ICTP, PINP, and BAP, and less levels of bone osteoblast and osteoclast activity were detected in the XZP-treated rats (P<0.05). Moreover, significantly increased levels of bone OPG but significantly decreased levels of RANL, RNAK, PTHrP, IGF-1, M-CSF, IL-8, and TNF-α were detected in the XZP-treated rats (P<0.05 for all). Together, XZP treatment significantly mitigated the cancer-induced bone damage and bone osteoclast and osteoblast activity and alleviated prostate cancer-induced bone pain by modulating the RANKL/RANK/OPG pathway and bone cancer-related inflammation in rats.

Osteolysis and pain due to experimental bone metastases are improved by treatment with rapamycin

In advanced breast cancer, bone metastases occur in 70 % of patients. Managing the devastating pain associated with the disease is difficult. Rapamycin is an immunomodulatory drug that targets the mammalian target of rapamycin pathway. Rapamycin has been shown to decrease osteolysis associated with metastatic breast cancer in pre-clinical models and to reduce pain in inflammatory and neuropathic models. The aim of this study was to evaluate the effectiveness of rapamycin in reducing pain associated with experimental osteolytic metastases. Bone cancer was induced by intra-tibial injections of murine mammary carcinoma cells (4T1) in immunocompetent BALB/c mice and treated intraperitoneally for up to 5 weeks with vehicle, rapamycin or pamidronate (a bisphosphonate currently used to reduce bone loss in bone cancer patients). The control group received intra-tibial injection with saline (sham) and was treated with vehicle intraperitoneally. Cancer-induced osteolysis was observed histologically and radiographically 2-3 weeks following cancer inoculation and gradually increased with time. Measures of evoked nociceptive behaviors including sensitivity to mechanical, thermal, and cold stimuli and spontaneous nociceptive behaviors (limping, guarding) were evaluated. Significant hypersensitivity to sensory stimuli developed in cancer-bearing mice compared to sham 3 weeks following inoculation. Rapamycin decreased or delayed the development of cancer-induced mechanical, heat, and cold hypersensitivity, while pamidronate reduced heat and cold hypersensitivity. Both rapamycin and pamidronate had a partial protective effect on the spontaneous nociceptive behaviors, limping and guarding. Our data suggest that rapamycin may have efficacy in the management of pain associated with metastatic breast cancer.

In vivo animal models of spinal metastasis

The vertebral column is the commonest site for skeletal metastases, with breast, prostate and lung cancers being the most common primary sources. The spine has structural and neural-protective properties thus involvement by metastatic cancer often causes bony instability and fracture, intractable pain and neurological deficit. In vivo animal models which resemble the human condition are essential in order to improve understanding of the pathophysiology behind the spread of metastatic cancer to the spine and its subsequent local growth and invasion, to enable in-depth analysis of the interaction between host and tumour cells and the molecular processes behind local cancer invasion and barriers to invasion as well as to allow assessment of novel treatment modalities for spinal metastases. This review summarizes the current status of the animal models specifically used for the study of spinal metastasis, their relevance, advantages and limitations, and important considerations for the development of future in vivo animal models.

A micro-imaging study linking bone cancer pain with tumor growth and bone resorption in a rat model

Bone metastases represent a frequent complication of advanced breast cancer. As tumor growth-induced bone remodeling progresses, episodes of severe pain and fractures of weight-bearing limbs increase. All of these skeletal-related events influence the patient's quality of life and survival. In the present study, we sought to determine whether some of these pain-related behaviors could be directly correlated to tumor progression and bone remodeling. For this purpose, we used a rat model of bone cancer pain based on the implantation of mammary carcinoma cells in the medullary cavity of the femur. The bone content and tumor growth were monitored over time by magnetic resonance imaging (MRI) and micro X-ray computed tomography (μCT). The same animals were evaluated for changes in their reflexive withdrawal responses to mechanical stimuli (allodynia) and weight-bearing deficits. As assessed by MRI, we found a negative correlation between tumor volume and allodynia or postural deficits throughout the experiment. Using μCT, we found that the bone volume/total volume (BV/TV) ratios for trabecular and cortical bone correlated with both mechanical hypersensitivity and weight-bearing impairment. However, whereas trabecular BV/TV stabilized between days 7 and 10 post-tumor detection, the cortical bone loss reached its maximum at that time. Our imaging approach also allowed us to consistently detect the tumor before the onset of pain, paving the way for the preemptive identification of at-risk patients. Altogether, these results improve our understanding of the events leading to tumor-induced bone pain and could eventually help in the design of novel strategies for the management of bone diseases.

Behavioral, medical imaging and histopathological features of a new rat model of bone cancer pain

Pre-clinical bone cancer pain models mimicking the human condition are required to respond to clinical realities. Breast or prostate cancer patients coping with bone metastases experience intractable pain, which affects their quality of life. Advanced monitoring is thus required to clarify bone cancer pain mechanisms and refine treatments. In our model of rat femoral mammary carcinoma MRMT-1 cell implantation, pain onset and tumor growth were monitored for 21 days. The surgical procedure performed without arthrotomy allowed recording of incidental pain in free-moving rats. Along with the gradual development of mechanical allodynia and hyperalgesia, behavioral signs of ambulatory pain were detected at day 14 by using a dynamic weight-bearing apparatus. Osteopenia was revealed from day 14 concomitantly with disorganization of the trabecular architecture (µCT). Bone metastases were visualized as early as day 8 by MRI (T(1)-Gd-DTPA) before pain detection. PET (Na(18)F) co-registration revealed intra-osseous activity, as determined by anatomical superimposition over MRI in accordance with osteoclastic hyperactivity (TRAP staining). Pain and bone destruction were aggravated with time. Bone remodeling was accompanied by c-Fos (spinal) and ATF3 (DRG) neuronal activation, sustained by astrocyte (GFAP) and microglia (Iba1) reactivity in lumbar spinal cord. Our animal model demonstrates the importance of simultaneously recording pain and tumor progression and will allow us to better characterize therapeutic strategies in the future.