Differential responses of fibroblasts, non-neoplastic epithelial cells, and oral carcinoma cells to low-level laser therapy

[Photobiomodulation in the prevention and the management of side effects of cancer treatments: Bases, results and perspectives]

BACKGROUND

Assess the current and potential indications of photobiomodulation (PBM) therapy and their level of evidence in the prevention or treatment of side effects related to oncology treatments (radiation therapy, and to a minimal extent favored and hematopoietic stem cell transplants). And report on the recommended modalities (parameters and doses) of PBM therapy.

MATERIALS AND METHODS

The Embase, Medline/PubMed, Cochrane, EBSCO, Scopus, and LILACS databases were systematically reviewed to include and analyze publications of clinical studies that evaluated PBM in the prevention or management side effects related to cancer treatments. The keywords used were "photobiomodulation"; "low level laser therapy"; "acute oral mucositis"; "acute dysphagia"; "acute radiation dermatitis"; "lymphedema"; "xerostomia"; "dysgeusia"; "hyposalivation"; "lockjaw"; "bone necrosis"; "osteoradionecrosis"; "radiation induced fibrosis"; "voice and speech alterations"; "palmar-plantar erythrodysesthesia"; "graft versus host disease"; "peripheral neuropathy"; "chemotherapy induced alopecia". Prospective studies were included, while retrospective cohorts and non-original articles were excluded from the analysis.

RESULTS

PBM in the red or infrared spectrum has been shown to be effective in randomized controlled trials in the prevention and management of certain complications related to radiotherapy, in particular acute mucositis, epitheliitis and upper limb lymphedema. The level of evidence associated with PBM was heterogeneous, but overall remained moderate. The main limitations were the diversity and the lack of precision of the treatment protocols which could compromise the efficiency and the reproducibility of the results of the PBM. For other effects related to chemo/radiation therapy (dysgeusia, osteonecrosis, peripheral neuropathy, alopecia, palmar-plantar erythrodysaesthesia) and haematopoietic stem cell transplantation (graft versus host disease), treatment with PBM suffers from a lack of studies or limited studies at the origin of a weakened level of proof. However, based on these results, it was possible to establish safe practice parameters and doses of PBM.

CONCLUSION

Published data suggest that PBM could therefore be considered as supportive care in its own right for patients treated with radiation, chemotherapy, immunotherapy, hormone therapy or targeted therapies, whether in clinical practice or clinical trials. therapies. However, until solid data have been published on its long-term safety, the use of PBM should be considered with caution and within the recommended parameters and doses, particularly when practiced in areas of known or possible tumours. In this case, the patient should be informed of the theoretical benefits and risks of PBM in order to obtain informed consent before treatment.

Monte Carlo based dosimetry of extraoral photobiomodulation for prevention of oral mucositis

Photobiomodulation therapy (PBMT) is recommended for prevention and treatment of oral mucositis, a painful condition that occurs in cancer patients. Intraoral PBMT is limited to treating distal oral mucosa and oropharynx. Extraoral PBMT may provide a more efficient intervention. The goal of this study was to develop a clinically viable protocol for extraoral PBMT. Monte Carlo modeling was used to predict the distribution of 850 nm light for four treatment sites, using anatomical data obtained from MRI and optical properties from the literature. Simulated incident light power density was limited to 399 mW/cm2 to ensure treatment safety and to prevent tissue temperature increase. The results reveal that total tissue thickness determines fluence rate at the oral mucosa, whereas the thickness of individual tissue layers and melanin content are of minor importance. Due to anatomical differences, the fluence rate varied greatly among patients. Despite these variations, a universal protocol was established using a median treatment time methodology. The determined median treatment times required to deliver efficacious dose between 1 and 6 J/cm2 were within 15 min. The developed PBMT protocol can be further refined using the combination of pretreatment imaging and the Monte Carlo simulation approach implemented in this study.

Effect of femtosecond laser interaction with human fibroblasts: a preliminary study

In in vitro methods and cell culture models, femtosecond (fs) laser interaction has been employed to assess its effect on the proliferation and morphology of human skin fibroblasts. We cultured a primary human skin fibroblast cell line on a glass plate, passages 17-23. The cells were irradiated with a 90-fs laser at a wavelength of 800 nm and a repetition rate of 82 MHz. The target received an average power of 320 mW for 5, 20, and 100 s, corresponding to the radiation exposures of 22.6, 90.6, and 452.9 J/cm2, respectively. Using a laser scanning microscopy technique, the photon densities were measured to be 6.4 × 1018, 2.6 × 1019, and 1.3 × 1020 photons/cm2 in a spot area of 0.07 cm2; the recorded spectra were obtained from the laser interaction after 0.00, 1.00, 25.00, and 45.00 h. The cell count and morphological changes showed that the cultured cells were affected by laser irradiation under photon stress; some fibroblasts were killed, while others were injured and survived. We discovered evidence of the formation of several coenzyme compounds, such as flavin (500-600 nm), lipopigments (600-750 nm), and porphyrin (500-700 nm). This study is motivated by the future development of a novel, ultra-short fs laser system and the need to develop a basic in vitro understanding of photon-human cell interaction. The cell proliferation indicated that cells are partly killed or wounded. The exposure of fibroblasts to fs laser fluence up to 450 J/cm2 accelerates cell growth of the viable residual cell.

Possible adverse effects of low-level laser on oral and oropharyngeal cancer cells: A scope review

BACKGROUND

The effects of laser therapy on normal cells are well known and accepted, but the impact of this therapy on malignant cells are not yet fully understood. This review aims to map and outline what the scientific literature addresses on the effects of laser therapy on malignant cells.

METHODS

This review article followed the guidelines of the PRISMA-ScR protocol, being all the search, analysis, and selection of articles based on it.

RESULTS

After all application of the predetermined criteria, five studies were included, dated between the years 2013 and 2021. With the complete reading of the selected studies, 100% of the articles were classified as category III of the Agency for Healthcare as Research and Quality classification. Similar themes among the papers included were investigated and compared. In these five studies, the visible red and near infrared wavelengths were used, and energy densities varied between 1 and 5 J/cm² . It was observed that low-level laser could alter the expression of cell proliferation and migration proteins, such as cyclin D1, E-cadherin, and β-catenin. In addition, changes related to increased cell viability and metabolism were also identified.

CONCLUSION

The low-level laser seems to positively regulate the proliferative, migratory, and viability capacity of neoplastic cells, depending on the protocol used. All these studies included in the review are equivalent to in vitro studies; the cells are not in such a complex environment as is an organized tissue, making it necessary to carry out more complex tests, such as in vivo research.

Stimulatory effects of wavelength-dependent photobiomodulation on proliferation and angiogenesis of colorectal cancer

In recent decades, the laser treatment of cancer has been introduced as a promising treatment option. Because of the maldistribution of optical energy and an ambiguous boundary between the normal and tumor tissues, laser irradiation can stimulate residual cancer cells, leading to a cancer regrowth. As photobiomodulation (PBM) is involved in an extensive range of cellular responses, profound comprehension of photo-stimulated mechanisms against the cancer cells is required to establish a safety margin for PBM. Therefore, we aimed to identify the stimulant effects of PBM at various wavelengths against the tumor cells to establish a safety margin for the laser treatment. CT26 murine colon cancer cells were exposed to either 405 (BL), 635 (VIS), or 808 (NIR) nm laser lights at the fluences of 0, 10, 30, and 50 J/cm². In addition, CT26 tumor-bearing mice were irradiated with BL, VIS, or NIR at a fluence of 30 J/cm². Both the proliferation and angiogenesis potential of the CT26 cells and tumors were evaluated using the MTT assay, western blot, and immunohistochemistry (IHC) staining analyses. Although cell viability was not statistically significant, BL significantly induced p-ERK upregulation in the CT26 cells, indicating that PBM with BL can stimulate proliferation. In vivo tests showed that the NIR group exhibited the maximum relative tumor volume, and BL yielded a slight increase compared to the control. In the IHC staining and western blot analyses, both BL and NIR increased the expression of EGFR, VEGF, MMP-9, and HIF-1α, which are related to the proliferation and angiogenesis-related factors. Further investigations will be pursued to clarify the molecular pathways that depend on the cancer cell types and laser wavelengths for the establishment of safety guidelines in clinical environments.

Photobiomodulation therapy in management of cancer therapy-induced side effects: WALT position paper 2022

Disclaimer

This article is based on recommendations from the 12th WALT Congress, Nice, October 3-6, 2018, and a follow-up review of the existing data and the clinical observations of an international multidisciplinary panel of clinicians and researchers with expertise in the area of supportive care in cancer and/or PBM clinical application and dosimetry. This article is informational in nature. As with all clinical materials, this paper should be used with a clear understanding that continued research and practice could result in new insights and recommendations. The review reflects the collective opinion and, as such, does not necessarily represent the opinion of any individual author. In no event shall the authors be liable for any decision made or action taken in reliance on the proposed protocols.

Objective

This position paper reviews the potential prophylactic and therapeutic effects of photobiomodulation (PBM) on side effects of cancer therapy, including chemotherapy (CT), radiation therapy (RT), and hematopoietic stem cell transplantation (HSCT).

Background

There is a considerable body of evidence supporting the efficacy of PBM for preventing oral mucositis (OM) in patients undergoing RT for head and neck cancer (HNC), CT, or HSCT. This could enhance patients’ quality of life, adherence to the prescribed cancer therapy, and treatment outcomes while reducing the cost of cancer care.

Methods

A literature review on PBM effectiveness and dosimetry considerations for managing certain complications of cancer therapy were conducted. A systematic review was conducted when numerous randomized controlled trials were available. Results were presented and discussed at an international consensus meeting at the World Association of photobiomoduLation Therapy (WALT) meeting in 2018 that included world expert oncologists, radiation oncologists, oral oncologists, and oral medicine professionals, physicists, engineers, and oncology researchers. The potential mechanism of action of PBM and evidence of PBM efficacy through reported outcomes for individual indications were assessed.

Results

There is a large body of evidence demonstrating the efficacy of PBM for preventing OM in certain cancer patient populations, as recently outlined by the Multinational Association for Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO). Building on these, the WALT group outlines evidence and prescribed PBM treatment parameters for prophylactic and therapeutic use in supportive care for radiodermatitis, dysphagia, xerostomia, dysgeusia, trismus, mucosal and bone necrosis, lymphedema, hand-foot syndrome, alopecia, oral and dermatologic chronic graft-versus-host disease, voice/speech alterations, peripheral neuropathy, and late fibrosis amongst cancer survivors.

Conclusions

There is robust evidence for using PBM to prevent and treat a broad range of complications in cancer care. Specific clinical practice guidelines or evidence-based expert consensus recommendations are provided. These recommendations are aimed at improving the clinical utilization of PBM therapy in supportive cancer care and promoting research in this field. It is anticipated these guidelines will be revised periodically.

Conservative treatment of lymphedema: the state of the art

This article aims to discuss the possibilities of conservative and non-pharmacological treatments for lymphedema. A non-systematic review of the literature was carried out, including studies involving human subjects with different types of lymphedema. Several approaches to lymphedema treatment have been reported and Complex Decongestive Therapy (CDT) has been considered the most effective treatment for limb lymphedema. Other conservative treatments have been proposed such as Taping, Extracorporeal Shock Wave Therapy, Acupuncture, Photobiomodulation Therapy, Endermologie, Intermittent Pneumatic Compression, and Low-frequency, Low-intensity Electrotherapy. The choice of the therapeutic approach to be employed should consider lymphedema characteristics, the therapist's experience, and the patient's wishes. In addition, since this is a chronic condition, the patient must adhere to the treatment. To this end, the therapeutic proposal may be the key to better control of limb volume.

Effects of photobiomodulation on the redox state of healthy and cancer cells

Photobiomodulation therapy (PBMT) uses light to stimulate cells. The molecular basis of the effects of PBMT is being unveiled, but it is stated that the cytochrome-c oxidase enzyme in mitochondria, a photon acceptor of PBMT, contributes to an increase in ATP production and modulates the reduction and oxidation of electron carriers NADH and FAD. Since its effects are not fully understood, PBMT is not used on tumors. Thus, it is interesting to investigate if its effects correlate to mitochondrial metabolism and if so, how it could be linked to the optical redox ratio (ORR), defined as the ratio of FAD/(NADH + FAD) fluorescences. To that end, fibroblasts (HDFn cell line) and oral squamous cell carcinoma (SCC-25 cell line) were irradiated with a light source of 780 nm and a total dose of 5 J/cm2, and imaged by optical microscopy. PBMT down-regulated the SCC-25 ORR by 10%. Furthermore, PBMT led to an increase in ROS and ATP production in carcinoma cells after 4 h, while fibroblasts only had a modest ATP increase 6 h after irradiation. Cell lines did not show distinct cell cycle profiles, as both had an increase in G2/M cells. This study indicates that PBMT decreases the redox state of oral cancer by possibly increasing glycolysis and affects normal and tumor cells through distinct pathways. To our knowledge, this is the first study that investigated the effects of PBMT on mitochondrial metabolism from the initiation of the cascade to DNA replication. This is an essential step in the investigation of the mechanism of action of PBMT in an effort to avoid misinterpretations of a variety of combined protocols.

Mechanisms of PhotoBioModulation (PBM) focused on oral mucositis prevention and treatment: a scoping review

Background

Oral mucositis (OM) is a severe complication cancer patients undergo when treated with chemoradiotherapy. Photobiomodulation (PBM) therapy also known as low-level laser therapy has been increasingly used for the treatment of such oral toxicity. The aim of this review is to discuss the mechanisms of photobiomodulation (PBM) regarding OM prevention and treatment, and more precisely to focus on the effect of PBM on tumor and healthy cells.

Methods

MEDLINE/PubMed, and google scholar were searched electronically. Selected studies were focusing on PBM effects on tumor and healthy cells.

Results

PBM interactions with the tissue and additional mechanism in OM therapy were detailed in this review. Moreover, this review highlighted a controversy about the carcinogenic effect of PBM. Indeed, Many studies reported that PBM could enhance malignant cell proliferation; suggesting that PBM would have no protective effect. In addition to acting on cancer cells, PBM may damage healthy cells.

Conclusion

More prospective studies are needed to assess the effect of PBM on cancer cells in order to improve its use for OM prevention and treatment.

Laser Photobiomodulation (PBM)-A Possible New Frontier for the Treatment of Oral Cancer: A Review of In Vitro and In Vivo Studies

The treatment of oral squamous cell carcinoma (OSCC) is particularly complex due to its aggressive behavior, location, the patient’s age, and its spread at diagnosis. In recent years, photobiomodulation (PBM) has been introduced in different medical fields; however, its application, in patients suffering from OSCC for palliative support or to induce analgesia, has been hotly debated due to the possibility that the cell growth stimuli induced by PBM could lead to a worsening of the lesions. The aim of this study is to review the literature to observe the available data investigating the effect of PBM on cancer cells in vitro and in vivo. A review was conducted on the PubMed and Scopus databases. A total of twelve studies met the inclusion criteria and were therefore included for quality assessment and data extraction. The analysis showed that the clinical use of PBM is still only partially understood and is, therefore, controversial. Some authors stated that it could be contraindicated for clinical use in patients suffering from SCC, while others noted that it could have beneficial effects. According to the data that emerged from this review, it is possible to hypothesize that there are possibilities for PBM to play a beneficial role in treating cancer patients, but further evidence about its clinical efficacy and the identification of protocols and correct dosages is still needed.

Effects of 660 nm and 810 nm Low-Power Diode Laser on Proliferation and Invasion of Oral Cancer Cells in Cell Culture Media

In the present study, the effects of 660 and 810 nm diode laser on the proliferation and invasion of cancer cells were investigated. Sixteen plates of oral cancer cells originated from tongue SCC were irradiated with diode laser at 660 nm (40 and 80 mW) and 810 nm (100 and 200 mW) with the energy density of 4 J cm^-2 . One plate received no irradiation (the control). Irradiation was performed at four times (0, 24, 72 and 168 h). Cell proliferation was measured by MTT assay. The Ki67 and vascular endothelial growth factor (VEGF) markers were examined by real-time polymerase chain reaction (RT-PCR). Cyclin D1, E-cadherin, β-catenin and matrix metalloproteinase-9 (MMP-9; flow cytometry) were also evaluated. Proliferation was lower in the irradiated groups. This result was significant for all groups at 24 h. The percentages of cyclin D1 and MMP-9 were higher in 810 nm groups, β-catenin and E-cadherin were higher in 660 nm groups, VEGF marker was significantly lower in 810 nm/200 mW group, and Ki67 marker has no difference between the groups. According to the results of this study, laser irradiation at 0 and 24 h resulted in a significant inhibitory effect on cell proliferation especially in 660 nm/80 mW and 810 nm/200 mW. Further studies are needed in this respect.

Safety and efficacy of photobiomodulation therapy in oncology: A systematic review

We performed a systematic review of the current literature addressing the safety and efficacy of photobiomodulation therapy (PBMT) in cancer patients. In this systematic review, the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines were used. In vitro, in vivo, and clinical studies, which investigated the effect of PBMT on cell proliferation/differentiation, tumor growth, recurrence rate, and/or overall survival were included. The Medline/PubMed, EMBASE, and Scopus databases were searched through April 2020. A total of 67 studies met the inclusion criteria with 43 in vitro, 15 in vivo, and 9 clinical studies identified. In vitro studies investigating the effect of PBMT on a diverse range of cancer cell lines demonstrated conflicting results. This could be due to the differences in used parameters and the frequency of PBM applications. In vivo studies and clinical trials with a follow‐up period demonstrated that PBMT is safe with regards to tumor growth and patient advantage in the prevention and treatment of specific cancer therapy‐related complications. Current human studies, supported by most animal studies, show safety with PBMT using currently recommended clinical parameters, including in Head & Neck cancer (HNC) in the area of PBMT exposure. A significant and growing literature indicates that PBMT is safe and effective, and may even offer a benefit in patient overall survival. Nevertheless, continuing research is indicated to improve understanding and provide further elucidation of remaining questions regarding PBM use in oncology.

Effects of photobiomodulation on cellular viability and cancer stem cell phenotype in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most common head and neck malignancy; it has been shown that cancer stem cells (CSC) are present in OSCC and associated with tumor growth, invasion, metastasis, and therapeutic resistance. Photobiomodulation (PBM) is an alternative tool for oncologic treatment adverse effects such as oral mucositis (OM); however, controversy exists regarding the undesirable effects of PBM on tumor or CSC. This study aimed to evaluate in vitro, the effects of PBM, with the same dosimetric parameters as those used in the clinic for OM prevention and treatment, on OSCC cellular viability, as well as PBM's effect on CSC properties and its phenotype. OSCC cell lines were submitted to single or daily PBM with 3 J/cm² and 6 J/cm² and then the cellular viability was evaluated by MTT, NRU (neutral red uptake), and CVS (crystal violet staining). The CSC populations were evaluated by clonogenic formation assay, flow cytometry, and RT-qPCR. The single PBM with the 3 J/cm² group was associated with increased cellular viability. Daily PBM with 3 J/cm² and 6 J/cm² was associated with a significant decrease in cellular viability. Additionally, daily PBM was not able to promote CSC self-renewal or the CD44^high/ESA^low and CD44^high/ESA^high cellular phenotypes. Moreover, a decrease in the number of spheres and in the expression of the CSC related gene BMI1 was observed after daily PBM with 6 J/cm². Daily PBM with 3 J/cm² and 6 J/cm² showed an inhibitory effect on cellular viability and was not able to promote the CSC self-renewal or phenotype.

Review on the Cellular Mechanisms of Low-Level Laser Therapy Use in Oncology

Photobiomodulation (PBM) using low-level laser therapy (LLLT) is a treatment that is increasingly used in oncology. Studies reported enhancement of wound healing with reduction in pain, tissue swelling and inflammatory conditions such as radiation dermatitis, oral mucositis, and lymphedema. However, factors such as wavelength, energy density and irradiation frequency influence the cellular mechanisms of LLLT. Moreover, the effects of LLLT vary according to cell types. Thus, controversy arose as a result of poor clinical response reported in some studies that may have used inadequately planned treatment protocols. Since LLLT may enhance tumor cell proliferation, these will also need to be considered before clinical use. This review aims to summarize the current knowledge of the cellular mechanisms of LLLT by considering its effects on cell proliferation, metabolism, angiogenesis, apoptosis and inflammation. With a better understanding of the cellular mechanisms, bridging findings from laboratory studies to clinical application can be improved.

Photobiomodulation Therapy in Oral Mucositis and Potentially Malignant Oral Lesions: A Therapy Towards the Future

Photobiomodulation therapy (PBMT) is an effective treatment modality, which has the significant advantage of enhancing a patient’s quality of life (QoL) by minimising the side effects of oral cancer treatments, as well as assisting in the management of potentially cancerous lesions. It is important to note that the major evidence-based documentation neither considers, nor tackles, the issues related to the impact of PBMT on tumour progression and on the downregulation of cellular proliferation improvement, by identifying the dose- and time-dependency. Moreover, little is known about the risk of this therapy and its safety when it is applied to the tumour, or the impact on the factor of QoL. The review aimed to address the benefits and limitations of PBMT in premalignant oral lesions, as well as the conflicting evidence concerning the relationship between tumour cell proliferation and the applied dose of photonic energy (fluence) in treating oral mucositis induced by head and neck cancer (H&N) treatments. The objective was to appraise the current concept of PBMT safety in the long-term, along with its latent impact on tumour reaction. This review highlighted the gap in the literature and broaden the knowledge of the current clinical evidence-based practice, and effectiveness, of PBMT in H&N oncology patients. As a result, the authors concluded that PBMT is a promising treatment modality. However, due to the heterogeneity of our data, it needs to undergo further testing in well-designed, long-term and randomised controlled trial studies, to evaluate it with diligent and impartial outcomes, and ensure laser irradiation’s safety at the tumour site.

Does low-level laser therapy affect the survival of patients with head and neck cancer?

Low-level laser therapy (LLLT) is used in patients with head and neck cancer (HNC) for treatment-related mucositis. There is conflicting evidence as to whether LLLT leads to the proliferation of tumor cells and whether it interferes with the tumoricidal effect of radiotherapy or chemoradiotherapy, if the tumor lies within the LLLT field. Using fuzzy matching, 126 HNC patients who had received LLLT including the tumor region and 126 matching HNC patients without LLLT (controls) treated at the Department of Otorhinolaryngology, Head & Neck Surgery, Medical University of Innsbruck, were identified. The overall survival was compared using the Kaplan-Meier analysis. Fuzzy matching yielded 2 patient samples well comparable in terms of risk of death. The survival did not significantly differ between patients with and without LLLT (p = 0.18). An increased risk of death in HNC patients who received LLLT covering the tumor region was not observed in our study.

Photobiomodulation effects on head and neck squamous cell carcinoma (HNSCC) in an orthotopic animal model

BACKGROUND

Photobiomodulation (PBM) has shown efficacy in preventing and treating cancer therapy-induced mucositis and dermatitis. However, there is contradictory information regarding the effect of PBM on (pre)malignant cells, which has led to questions regarding the safety of this technique. We address this issue using an orthotopic mouse model (Cal-33) with human squamous cell carcinoma of the oral cavity.

METHODS

Mice with actively growing orthotopic Cal-33 head and neck carcinoma tumors were divided into 4 groups: control, PBM only, radiation therapy (RT) only, and PBM + RT. We performed three experiments: (1) PBM at 660 nm, 18.4 J/cm², and 5 RT × 4 Gy doses delivered daily; (2) PBM at 660 nm, 18.4 J/cm², and 1 × 15 Gy RT; and (3) PBM at 660 nm + 850 nm, 45 mW/cm², 3.4 J/cm², and 1 × 15 Gy RT. Mice were weighed daily and tumor volumes were evaluated by IVIS. Survival time was also evaluated.

RESULTS

Animals treated with RT survived significantly longer and had significantly smaller tumor volume when compared with the control and PBM-only treatment groups. No significant differences were noted between the RT alone and PBM + RT groups in any of the experiments.

CONCLUSION

Our results suggest that PBM at the utilized parameters does not provide protection to the tumor from the killing effects of RT.

Percutaneous Exposures of volunteers to polychromatic light (480-3400 nm) trigger systemic mechanism of the human myeloma cells growth delay without any effect on bortezomib cytotoxicity in vitro

Background and aim

Polychromatic light is actively used in medicine. However, its oncological safety and effect against cytotoxic therapy remains poorly studied. Multiple myeloma (MM) develops in the bone marrow and therefore malignant plasma cells are inaccessible to direct exposure to light. The aim of our work was to study the influence of polychromatic visible and infra-red light (pVIS + pIR) on growth and sensitivity of the myeloma cells to the cytotoxic effect of drug bortezomib (BTZ) through systemic mechanism.

Materials and methods

We explored the effect of volunteers blood sera after their 4-daily irradiations with pVIS + pIR light (480-3400 nm) on growth and viability of the human myeloma RPMI 8226 cells in the presence of BTZ at its application in 2 modes: short-term (1 h, 300 nM) and long-term ( 96 h, 5 nM). Viability and proliferative activity of cells was evaluated by MTT assay.

Results

It was found that photomodified blood sera delayed growth of myeloma RPMI 8226 cells (by 25 % in 48 h and 23 % in 96 h) but had no effect on spontaneous and mitogen-induced proliferation of autologous peripheral blood T- and B-lymphocytes. We also revealed that pVIS + pIR did not change RPMI 8226 cells sensitivity to BTZ.

Conclusion

The results suggest the systemic mechanism of polychromatic light and argue in favor of its oncological safety during/after BTZ therapy of MM patients without effect on the drug cytotoxicity.

Tumor safety and side effects of photobiomodulation therapy used for prevention and management of cancer treatment toxicities. A systematic review

Photobiomodulation therapy (PBMT), also known as low-level laser therapy (LLLT), has been increasingly used for the treatment of toxicities related to cancer treatment. One of the challenges for the universal acceptance of PBMT use in cancer patients is whether or not there is a potential for the light to stimulate the growth of residual malignant cells that evaded oncologic treatment, increasing the risk for tumor recurrences and development of a second primary tumor. Current science suggests promising effects of PBMT in the prevention and treatment of breast cancer-related lymphedema and oral mucositis, among other cancer treatment toxicities. Nevertheless, this seems to be the first systematic review to analyze the safety of the use of PBMT for the management of cancer-related toxicities. Scopus, MEDLINE/PubMed, and Embase were searched electronically. A total of 27 articles met the search criteria. Selected studies included the use of PBMT for prevention and treatment of oral mucositis, lymphedema, radiodermatitis, and peripheral neuropathy. Most studies showed that no side effects were observed with the use of PBMT. The results of this systematic review, based on current literature, suggest that the use of PBMT in the prevention and management of cancer treatment toxicities does not lead to the development of tumor safety issues.

Examining tumor modulating effects of photobiomodulation therapy on head and neck squamous cell carcinomas

The aim of the present systematic review was to analyze studies that investigated the effects of photobiomodulation therapy on head and neck squamous cell carcinoma cells.

Low-Level Laser Therapy Stimulates Proliferation in Head and Neck Squamous Cell Carcinoma Cells

Objectives: Low-level laser therapy (LLLT) is a promising non-invasive treatment option for oropharyngeal mucositis, which is a common side effect of many oncological treatments. LLLT is known for its wound healing properties due to the stimulation of cellular processes, such as proliferation, migration and differentiation. Controversy exists on the possible stimulatory effect of LLLT on head and neck cancer (HNSCC) cells in patients treated with radiotherapy. The aim of this study was to evaluate the biostimulatory effect together with the underlying mechanisms of LLLT on HNSCC cancer cells and normal epithelial cells. Materials and methods: HNSCC cell lines (SCC154, SQD9, and SCC61) and human tonsil epithelial cells were exposed to a Gallium-Aluminum-Arsenide diode laser (830 nm, 150 mW) with energy densities of 0, 1, and 2 J/cm2. The proliferation potential of the cells was assessed by Sulforhodamine B assay, immunoblotting (mitogenic pathways), immunocytochemistry (Ki67), and flow cytometry (PI cell cycle staining). Results: Cell proliferation was increased in HNSCC cell lines after laser irradiation with 1 J/cm2, whereas no significant increase was seen after laser irradiation with 2 J/cm2. In contrast, no effect on cell proliferation was seen in the human tonsil epithelial cells after laser irradiation with any of the energy densities. The increased proliferation was associated with elevated levels of pAKT, pERK, and Ki67 protein expression and cell cycle progression. Conclusion: Our results show that LLLT increases cell proliferation in a dose-dependent manner in HNSCC cells but not in normal epithelial tonsil cells. These results suggest that LLLT has to be used with caution when treating oropharyngeal mucositis in HNSCC patients since tumor cells present in the LLLT irradiation field could be triggered by LLLT.

Treatment of mucositis with combined 660- and 808-nm-wavelength low-level laser therapy reduced mucositis grade, pain, and use of analgesics: a parallel, single-blind, two-arm controlled study

Oral squamous cell carcinoma (OSCC) is the most frequent oral malignant neoplasia. As consequence of OSCC treatment, oral mucositis (OM) is one of the most common adverse effects of OSCC treatment. Currently, there is no consensus for OM treatment. The purpose of the current study was to test the combination of red and infrared low-level laser therapy (LLLT) for OM treatment. Primary culture of human fibroblast was performed to identify LLLT dose. After laboratory tests, a two-arm parallel, single-blind, controlled study was conducted. The two arms were group 1, both 660- and 808-nm wavelengths (300 J/cm², 9 J of total energy, 100 mW, spot size 3 mm²), and group 2, only 660-nm wavelength (300 J/cm², 9 J of total energy, 100 mW, spot size 3 mm²). Both treatments were performed twice a week. Group 1 presented a reduction of mucositis grade in comparison to group 2. Group 1 also presented reduction of analgesics prescription. But no significant differences between groups 1 and 2 were observed according to the pain scale. In conclusion, the current study demonstrated that a combination of red and infrared at a higher dose (300 J/cm²) reduced both oral mucositis grade and analgesics prescription. The effects of the combination of RT and LLLT are unclear and need more studies.

Photodynamic Effect of Methylene Blue and Low Level Laser Radiation in Head and Neck Squamous Cell Carcinoma Cell Lines

Photodynamic therapy (PDT) is suggested to have an impact on the treatment of early stage head and neck cancers (HNSCC). We investigated the effect of PDT with methylene blue (MB) and a diode laser (660 nm) as the laser source on HNSCC cell lines as an in vitro model of surface oral squamous cell carcinoma. Cell-cultures were exposed to 160 µM MB for 4 min and to laser light for 8 min. Viability was proven via cell viability assay and clonogenic survival via clone counting assay. The combination of MB and diode laser evidenced high efficient loss of cell viability by 5% of the control, while treatment with the same concentration of MB for 4 min alone showed a viability of 46% of the control. In both SCC-25 and Detroit 562 HNSCC cells, MB combined with the laser allowed a significant abrogation of clonogenic growth (p < 0.01), especially in the case of Detroit 562 cells less than 1% of the suspension plated cells were able to grow tumor cell nests. Multiresistant (Detroit 562) HNSCC cells expressing cancer stem cell markers are sensitive to MB/red laser combined PDT.

Effect of 660 nm visible red light on cell proliferation and viability in diabetic models in vitro under stressed conditions

The current study evaluated the photobiomodulatory effect of visible red light on cell proliferation and viability in various fibroblast diabetic models in vitro, namely, unstressed normal (N) and stressed normal wounded (NW), diabetic wounded (DW), hypoxic wounded (HW) and diabetic hypoxic wounded (DHW). Cells were irradiated at a wavelength of 660 nm with a fluence of 5 J/cm² (11.23 mW/cm²), which related to an irradiation time of 7 min and 25 s. Control cells were not irradiated (0 J/cm²). Cells were incubated for 48 h and cellular proliferation was determined by measuring 5-bromo-2'-deoxyuridine (BrdU) in the S-phase (flow cytometry), while viability was assessed by the Trypan blue exclusion test and Apoptox-glo triplex assay. In comparison with the respective controls, PBM increased viability in N- (P ≤ 0.001), HW- (P ≤ 0.01) and DHW-cells (P ≤ 0.05). HW-cells showed a significant progression in the S-phase (P ≤ 0.05). Also, there was a decrease in the G2M phase in HW- and DHW-cells (P ≤ 0.05 and P ≤ 0.05, respectively). This study concludes that hypoxic wounded and diabetic hypoxic wounded models responded positively to PBM, and PBM does not damage stressed cells but has a stimulatory effect on cell viability and proliferation to promote repair and wound healing. This suggests that the more stressed the cells are the better they responded to photobiomodulation (PBM).

Prevention of acute radiodermatitis by photobiomodulation: A randomized, placebo-controlled trial in breast cancer patients (TRANSDERMIS trial)

OBJECTIVE

Acute radiodermatitis (RD) is a distressing and painful skin reaction that occurs in 95% of the patients undergoing radiotherapy (RT). The aim of this study was to evaluate the effectiveness of photobiomodulation therapy (PBMT) in the prevention of acute RD in breast cancer (BC) patients undergoing RT.

METHODS

This study was a randomized, placebo-controlled trial including 120 BC patients that underwent an identical RT regimen post-lumpectomy. Patients were randomly assigned to the laser therapy (LT) or placebo group, with 60 patients in each group. Laser or placebo treatments were applied 2 days a week, immediately after the RT session, starting at the first day of RT. PBMT was delivered using a class IV MLS® M6 laser that combines two synchronized laser diodes in the infrared range (808-905 nm) with a fixed energy density (4 J/cm2 ). Skin reactions were scored based on the criteria of the Radiation Therapy Oncology Group (RTOG) and the Radiation-Induced Skin Reaction Assessment Scale (RISRAS). The patients completed the Skindex-16 questionnaire to evaluate their quality of life. All the measurements were collected at the first day, at a RT dose of 40 Gray (Gy), and at the end of RT (total dose 66 Gy).

RESULTS

At a RT dose of 40 Gy, there was no significant difference between the groups in the distribution of RTOG grades. However, at the end of RT the severity of the skin reactions significantly differed between the two groups (P = 0.004), with a larger percentage of patients experiencing RTOG grade 2 or higher (e.g., moist desquamation) in the placebo group (30% vs. 6.7%, for the placebo and laser group, resp.). The objective RISRAS score confirmed these results. In addition, the Skindex-16 and RISRAS subjective score demonstrated that the patients' quality of life was significantly better in the LT than in the control group.

CONCLUSIONS

The results of this trial show that PBMT is an effective tool to prevent the development of grade 2 acute RD or higher in BC patients. In addition, it also reduces the patients' symptoms related to RD. Lasers Surg. Med. © 2018 Wiley Periodicals, Inc.

A systematic review and meta-analysis of the effect of low-level laser therapy (LLLT) on chemotherapy-induced oral mucositis in pediatric and young patients

Oral mucositis is one of the most frequent complications after chemotherapy, occurring in approximately 52 to 80% of children receiving treatment for cancer. Recently, it has been suggested that the use of low-energy laser could reduce the grade of oral mucositis and alleviate the symptoms. In 2014, Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology has recommended low-level laser therapy in prevention of mucositis for hematopoietic stem cell transplantation patients because of its beneficial effects in majority of recent studies. However, the recommendation was made for adult patients, not pediatric patients. Data about the effect of low-level laser therapy in pediatric patients is limited. This study aims to synthesize the available clinical evidences on the effects of low-level laser therapy (LLLT) in the prevention and treatment of chemotherapy-induced oral mucositis (OM). A meta-analysis was performed using trials identified through the Cochrane Central Register of Controlled Trials, Embase, MEDLINE, Web of Science, China Biology Medicine (CBM), Wanfang Database, and China National Knowledge Infrastructure (CNKI). Data on occurrence, duration, and severity of oral mucositis were collected. All randomized controlled studies and clinical controlled studies comparing LLLT to routine qualified prevention or treatment during or after chemotherapy were critically appraised and analyzed. We found 8 qualified clinical trials with a total of 373 pediatric patients; the methodological quality was acceptable. After prophylactic LLLT, the odds ratio for developing OM was significantly lower compared with placebo(OR = 0.50, 95% CI 0.29 to 0.87, P = 0.01), the odds ratio for developing grade III OM or worse was statistically significantly lower compared with placebo (OR = 0.30, 95% CI (0.10, 0.90), P = 0.03), and the OM severity was statistically significantly lower compared with placebo (SMD = - 0.56, 95% CI (- 0.98, - 0.14), P = 0.009). For therapeutic LLLT, the OM severity was significantly reduced compared to routine care (SMD = - 1.18, 95% CI (- 1.52, - 0.84), P < 0.00001). Oral pain was also reduced after LLLT over routine care (MD = - 0.73, 95% CI (- 1.36, - 0.11), P = 0.02).

CONCLUSION

Prophylactic LLLT reduces mucositis and severe mucositis and decreases the average severity of oral mucositis in pediatric and young patients with cancer. Therapeutic LLLT also reduces the average severity of oral mucositis and oral pain. Further research should investigate the optimal parameter of LLLT in pediatric and young patients, and studies with higher methodological quality should be performed. What is known: • Low-level laser therapy (LLLT) was recommended by Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology; however, evidences about LLLT on oral mucositis in pediatric and young patients were insufficient and lack supportive synthesized data. • Recently, there have been several new RCTs or CCTs for pediatric patients or young adults. What is new: • Prophylactic LLLT reduces the occurrence of mucositis and severe mucositis and decreases the average severity of oral mucositis in pediatric and young patients. • Therapeutic LLLT reduces the average severity of oral mucositis and oral pain.

Epithelial-mesenchymal crosstalk induces radioresistance in HNSCC cells

Objective

Epithelial-mesenchymal crosstalk (EMC) contributes to tumor progression, chemoresistance and acquisition of a mesenchymal phenotype (EMT) of cancer cells. This study aims to investigate the effects of EMC on radioresistance in head and neck squamous cell carcinoma (HNSCC) cells.

Methods

In tumor cell lines, the response of HNSCC cells, stimulated with EMC conditioned medium (CM), to irradiation was evaluated with viability and clonogenic assays. Dose modifying factors (DMF) were calculated from the results of clonogenic assays. Potential pathways involved in radioresistance were analyzed with quantitative Real-Time PCR and western blot.

Results

CM significantly reduced the doubling time of SCC-25 cells (from 32.8 hours to 16.8 hours, p=0.0001) and Detroit 562 cells (from 88.5 hours to 29.6 hours, p=0.014). Further it increased clonogenic survival after irradiation. The DMF of CM was 2.04 ± 0.43 (mean ± standard deviation) for SCC-25 cells (p=0.015) and 2.14 ± 0.34 for Detroit 562 cells (p=0.008). Treatment with CM more than tripled the ERCC1 and survivin gene expression in SCC-25 cells.

Conclusion

EMC induced pathways involved in cell survival and DNA repair and led to increased radioresistance in HNSCC cells.

Low level laser therapy induces increased viability and proliferation in isolated cancer cells

OBJECTIVES

Low level laser therapy (LLLT), which stimulates natural biological processes in the application region, is frequently used in dental treatments. The aim of our study was to evaluate the effects of LLLT which could activate precancerous cells or increase existing cancerous tissue in case of clinically undetectable situations.

MATERIALS AND METHODS

Saos-2 osteoblast-like osteosarcoma cells and A549 human lung carcinoma cells were used. Twenty-four hours after preparation of cell culture plates, laser irradiation was performed 1, 2 and 3 times according to the test groups using Nd:YAG laser with the power output 0.5, 1, 2 and 3 W. Cell proliferation analysis was performed by MTT assay at the 24th hour following the last laser applications.

RESULTS

Generally, it was observed that the proliferation rates increased as the number of applications increased, when compared to the controls, especially in those cases in which the irradiation was performed 2 or 3 times more.

CONCLUSION

The findings of this study have led to the conclusion that LLLT increases cancer cell proliferation, depending on the power output level of the laser and the number of applications. In addition to the proliferation and mitotic activity of the cancer tissue cells, we concluded that LLLT, which is frequently used in dental practice, could activate precancerous cells or increase existing cancerous tissue.

Laser photobiomodulation of pro-inflammatory mediators on Walker Tumor 256 induced rats

Laser photobiomodulation or low-level laser therapy (LLLT) is recognized worldwide for its expansive use in medicine. LLLT has been reported to increase enzymatic activity, increasing the mitochondrial transmembrane potential, leading to an increased energy availability and signal transduction. Nevertheless, an inhibitory effect is also observed by the production of excessive ROS which can result the shutdown of mitochondrial energy production, and finally to apoptosis. However, the mechanism of apoptosis induced by LLLT is still not well understood. The main objective of the present study was to investigate the hypothesis that LLLT induces oxidative stress and stimulates the generation of pro-inflammatory markers interfering in tumor progression.

METHODS

Seventy-two female Walker Tumor induced Wistar rats (eight weeks of age, 200g body weight) were used for this study. TW-256 cells were suspended in phosphate buffered saline and then subcutaneously inoculated at 1×107viabletumorcells/ml per rat into the right flank (tumor-bearing rats). After a period of 14days in order to assess the development of the solid tumor mass, the animals were randomized and distributed in four groups (n=8 animals/group): (1) Control or irradiated by LLLT (2) Laser 1J - 35,7J/cm², (3) Laser 3J - 107,14J/cm² and (4) Laser 6J - 214,28J/cm²; (Thera Laser - 660nm, 100mW DMC®, São Carlos, Brazil) at four equidistant points according to their respective treatment groups, conducted three times on alternate days. The regulation and expression of inflammatory mediators IL-1β, IL-6, IL-10, TNF-α was assessed by ELISA and gene expression of COX-1, COX-2, iNOS, eNOS was analyzed by RT-PCR.

RESULTS

We found that the 1Joule (J) treated group promoted a significant increase in the levels of different inflammatory markers IL-1β, the gene expression of COX-2, iNOS, which was statistically different (p<0.05) when compared among different treatment and control groups. With Respect IL-6, IL-10, TNF-α levels statistically significant reduce was observed in 1Joule treated group when comparing to different energies groups and control group.

CONCLUSION

Our results suggest the evidence 1J-35,7J/cm² treatment was able to produce cytotoxic effects by generation of ROS causing acute inflammation and thus may be employed as the best energy dose associated with Photodynamic Therapy.

Tumor-associated fibroblast-conditioned medium induces CDDP resistance in HNSCC cells

Objective

EMT (epithelial to mesenchymal transition) contributes to tumor progression and metastasis. We aimed to investigate the effects of EMT on CDDP resistance in HNSCC (head and neck squamous cell carcinoma)-cells.

Methods

EMT was induced using conditioned medium from a tumor cell/fibroblast co-culture. HNSCC cells were alternatively treated with TGF-β1. The response to CDDP was evaluated with viability and clonogenic assays.

Results

Treatment of SCC-25/Detroit 562 cells with conditioned medium increased viability of the tumor cells. Moreover, it doubled the IC₅₀ of CDDP of SCC-25 cells from 6.2 μM to 13.1 μM (p < 0.001). The IC₅₀ of CDDP of Detroit 562 cells was increased following treatment with conditioned medium from 13.1 μM to 26.8 μM (p < 0.01). Colony forming ability after treatment with 5 or 10 μM CDDP was significantly higher in HNSCC cells treated with co-culture conditioned medium than in controls (p < 0.05). Treatment with TGF-β1 had no effect on the IC₅₀ of CDDP (p > 0.1).

Conclusions

Cell free medium from a co-culture was able to induce EMT in HNSCC cells. Co-culture treated HNSCC cells revealed increased viability and were less sensitive to CDDP treatment. TGF-β1 also induced a mesenchymal phenotype, but did not alter resistance to CDDP in HNSCC cells.

Exploring the effects of low-level laser therapy on fibroblasts and tumor cells following gamma radiation exposure

Ionizing radiation (IR) induces DNA damage and low-level laser therapy (LLLT) has been investigated to prevent or repair detrimental outcomes resulting from IR exposure. Few in vitro studies, however, explore the biological mechanisms underlying those LLLT benefits. Thus, in this work, fibroblasts and tumor cells are submitted to IR with doses of 2.5 Gy and 10 Gy. After twenty-four-h, the cells are exposed to LLLT with fluences of 30 J cm^-2 , 90 J cm^-2 , and 150 J cm^-2 . Cellular viability, cell cycle phases, cell proliferation index and senescence are evaluated on days 1 and 4 after LLLT irradiation. For fibroblasts, LLLT promotes - in a fluence-dependent manner - increments in cell viability and proliferation, while a reduction in the senescence was observed. Regarding tumor cells, no influences of LLLT on cell viability are noticed. Whereas LLLT enhances cell populations in S and G₂ /M cell cycle phases for both cellular lines, a decrease in proliferation and increase in senescence was verified only for tumor cells. Putting together, the results suggest that fibroblasts and tumor cells present different responses to LLLT following exposure to gamma-radiation, and these promising results should stimulate further investigations. Senescence of tumor cells and fibroblasts on the 4^th day after ionizing radiation (IR) and low-level laser therapy (LLLT) exposures. The number of senescent cells increased significantly for tumor cells (a) while for fibroblasts no increment was observed (b). The blue collor indicates senescence activity.

Photomodulation of the osteoclastogenic potential of oral squamous carcinoma cells

The treatment for oral cancer usually involves surgical excision followed by chemotherapy and/or radiotherapy. The combination of these therapies generally promotes a serious inflammation of the mucosa of the digestive tract, denominated mucositis, which compromises continuity of treatment. Photobiomodulation (PBM) therapy has been used successfully to reduce the oral mucositis, however there is still some controversy regarding the effects of this therapy on unintentionally irradiated tumor cells that may remain after cancer treatment. The aim of this study was to analyze the effect of PBM therapy (using parameters for mucositis) on the modulation of osteoclastogenic potential of a cell line derived from human lingual squamous cell carcinoma (SCC9). Previously irradiated SCC9 cells were co-cultured with human osteoclast precursors. Co-cultures performed with non-irradiated SCC9 cells served as control. After 7, 14 and 21 days the co-cultures were evaluated for the tartrate-resistant acid phosphatase (TRAP) activity, an osteoclastogenic marker. Additionally, the monocultures of SCC9 cells (non-irradiated and irradiated) were analyzed for cell viability/proliferation and for the expression of IL-11 and PTHrP. The irradiation of SCC9 cells with PBM with an energy density of 4 J/cm² decreased the pro-osteoclastogenic potential of those cells. This may represent a potential useful side effect of PBM therapy. PBM (using recommended parameters for mucositis treatment) decreases the osteoclastogenic potential of oral squamous carcinoma cells.

Laser Therapy Inhibits Tumor Growth in Mice by Promoting Immune Surveillance and Vessel Normalization

Laser therapy, recently renamed as photobiomodulation, stands as a promising supportive treatment for oral mucositis induced by oncological therapies. However, its mechanisms of action and, more importantly, its safety in cancer patients, are still unclear. Here we explored the anti-cancer effect of 3 laser protocols, set at the most commonly used wavelengths, in B16F10 melanoma and oral carcinogenesis mouse models. While laser light increased cell metabolism in cultured cells, the in vivo outcome was reduced tumor progression. This striking, unexpected result, was paralleled by the recruitment of immune cells, in particular T lymphocytes and dendritic cells, which secreted type I interferons. Laser light also reduced the number of highly angiogenic macrophages within the tumor mass and promoted vessel normalization, an emerging strategy to control tumor progression. Collectively, these results set photobiomodulation as a safety procedure in oncological patients and open the way to its innovative use for cancer therapy.

•

Laser light reduces tumor progression while increasing metabolism of cultured cells

•

Laser-treated tumors contain mature vessels and less pro-angiogenic macrophages

•

Tumors treated by photobiomodulation are surrounded by lymphocytes and dendritic cells

•

Laser light promotes secretion of type I interferons in vitro and in vivo

Laser therapy, also named photobiomodulation, is recommended to heal mucositis induced by oncological treatments, raising concerns on its safe use in cancer patients. Ottaviani et al. showed that laser light inhibits tumor progression, induces tumor vessel normalization and stimulates the immune system to produce type I interferons, proving the safety and extending the use of laser-based therapies to cancer.

The role of photobiomodulation on gene expression of cell adhesion molecules in diabetic wounded fibroblasts in vitro

Cell adhesion molecules (CAMs) are cell surface glycoproteins that facilitate cell-cell contacts and adhesion with the extracellular matrix (ECM). Cellular adhesion is affected by various disease conditions, such as diabetes mellitus (DM) and inflammation. Photobiomodulation (PBM) stimulates biological processes and expression of these cellular molecules. The aim of this experimental work was to demonstrate the role of PBM at 830nm on CAMs in diabetic wounded fibroblast cells. Isolated human skin fibroblast cells were used. Normal (N-) and diabetic wounded (DW-) cells were irradiated with a continuous wave diode laser at 830nm with an energy density of 5J/cm(2). Real time reverse transcriptase polymerase chain reaction (RT-PCR) was used to determine the relative gene expression of 39 CAMs 48h post-irradiation. Normalized expression levels from irradiated cells were calculated relative to non-irradiated control cells according to the 2^(-ΔΔCt) method. Thirty-one genes were significantly regulated in N-cells (28 were genes up-regulated and three genes down-regulated), and 22 genes in DW-cells (five genes were up-regulated and 17 genes down-regulated). PBM induced a stimulatory effect on various CAMs namely cadherins, integrins, selectins and immunoglobulins, and hence may be used as a complementary therapy in advancing treatment of non-healing diabetic ulcers. The regulation of CAMs as well as evaluating the role of PBM on the molecular effects of these genes may expand knowledge and prompt further research into the cellular mechanisms in diabetic wound healing that may lead to valuable clinical outcomes.

Low level laser therapy/photobiomodulation in the management of side effects of chemoradiation therapy in head and neck cancer: part 1: mechanisms of action, dosimetric, and safety considerations

PURPOSE

There is a large body of evidence supporting the efficacy of low level laser therapy (LLLT), more recently termed photobiomodulation (PBM), for the management of oral mucositis (OM) in patients undergoing radiotherapy for head and neck cancer (HNC). Recent advances in PBM technology, together with a better understanding of mechanisms involved, may expand the applications for PBM in the management of other complications associated with HNC treatment. This article (part 1) describes PBM mechanisms of action, dosimetry, and safety aspects and, in doing so, provides a basis for a companion paper (part 2) which describes the potential breadth of potential applications of PBM in the management of side-effects of (chemo)radiation therapy in patients being treated for HNC and proposes PBM parameters.

METHODS

This study is a narrative non-systematic review.

RESULTS

We review PBM mechanisms of action and dosimetric considerations. Virtually, all conditions modulated by PBM (e.g., ulceration, inflammation, lymphedema, pain, fibrosis, neurological and muscular injury) are thought to be involved in the pathogenesis of (chemo)radiation therapy-induced complications in patients treated for HNC. The impact of PBM on tumor behavior and tumor response to treatment has been insufficiently studied. In vitro studies assessing the effect of PBM on tumor cells report conflicting results, perhaps attributable to inconsistencies of PBM power and dose. Nonetheless, the biological bases for the broad clinical activities ascribed to PBM have also been noted to be similar to those activities and pathways associated with negative tumor behaviors and impeded response to treatment. While there are no anecdotal descriptions of poor tumor outcomes in patients treated with PBM, confirming its neutrality with respect to cancer responsiveness is a critical priority.

CONCLUSION

Based on its therapeutic effects, PBM may have utility in a broad range of oral, oropharyngeal, facial, and neck complications of HNC treatment. Although evidence suggests that PBM using LLLT is safe in HNC patients, more research is imperative and vigilance remains warranted to detect any potential adverse effects of PBM on cancer treatment outcomes and survival.

Low level laser therapy/photobiomodulation in the management of side effects of chemoradiation therapy in head and neck cancer: part 1: mechanisms of action, dosimetric, and safety considerations

PURPOSE

There is a large body of evidence supporting the efficacy of low level laser therapy (LLLT), more recently termed photobiomodulation (PBM), for the management of oral mucositis (OM) in patients undergoing radiotherapy for head and neck cancer (HNC). Recent advances in PBM technology, together with a better understanding of mechanisms involved, may expand the applications for PBM in the management of other complications associated with HNC treatment. This article (part 1) describes PBM mechanisms of action, dosimetry, and safety aspects and, in doing so, provides a basis for a companion paper (part 2) which describes the potential breadth of potential applications of PBM in the management of side-effects of (chemo)radiation therapy in patients being treated for HNC and proposes PBM parameters.

METHODS

This study is a narrative non-systematic review.

RESULTS

We review PBM mechanisms of action and dosimetric considerations. Virtually, all conditions modulated by PBM (e.g., ulceration, inflammation, lymphedema, pain, fibrosis, neurological and muscular injury) are thought to be involved in the pathogenesis of (chemo)radiation therapy-induced complications in patients treated for HNC. The impact of PBM on tumor behavior and tumor response to treatment has been insufficiently studied. In vitro studies assessing the effect of PBM on tumor cells report conflicting results, perhaps attributable to inconsistencies of PBM power and dose. Nonetheless, the biological bases for the broad clinical activities ascribed to PBM have also been noted to be similar to those activities and pathways associated with negative tumor behaviors and impeded response to treatment. While there are no anecdotal descriptions of poor tumor outcomes in patients treated with PBM, confirming its neutrality with respect to cancer responsiveness is a critical priority.

CONCLUSION

Based on its therapeutic effects, PBM may have utility in a broad range of oral, oropharyngeal, facial, and neck complications of HNC treatment. Although evidence suggests that PBM using LLLT is safe in HNC patients, more research is imperative and vigilance remains warranted to detect any potential adverse effects of PBM on cancer treatment outcomes and survival.

Effects of pre-radiation exposure to LLLT of normal and malignant cells

PURPOSE

Low-level laser therapy (LLLT) efficacy for the prevention of cancer treatment-induced oral mucositis (OM) has been amply described. However, potential protection of malignant cells remains a legitimate concern for clinicians. We tested LLLT-induced protection from ionizing radiation killing in both malignant and normal cells.

METHODS

We treated six groups each of normal human lymphoblasts (TK6) and human leukemia cells (HL60) with He-Ne LLLT (632.8 nm, 35 mW, CW, 1 cm(2), 35 mW/cm(2) for 3-343 s, 0.1-12 J/cm(2)) prior to exposure to ionizing radiation (IR). Cells were then incubated and counted daily to determine their survival. Optimization of IR dose and incubation time was established prior to testing the effect of LLLT.

RESULTS

Growth curves for both cell lines showed significant declines after exposure to 50-200 cGy IR when compared to controls. Pre-radiation exposure to LLLT (4.0 J/cm(2)) followed by 1-h incubation blocked this decline in TK6 but not in HL60 cells. The latter cells were sensitized to the killing effects of IR in a dose-dependent manner.

CONCLUSION

This study shows that pre-IR LLLT treatment results in a differential response of normal vs. malignant cells, suggesting that LLLT does not confer protection and may even sensitize cancer cells to IR killing.

Low-level laser irradiation promotes the proliferation and maturation of keratinocytes during epithelial wound repair

Low-level laser therapy (LLLT) has been extensively employed to improve epithelial wound healing, though the exact response of epithelium maturation and stratification after LLLT is unknown. Thus, this study aimed to assess the in vitro growth and differentiation of keratinocytes (KCs) and in vivo wound healing response when treated with LLLT. Human KCs (HaCaT cells) showed an enhanced proliferation with all the employed laser energy densities (3, 6 and 12 J/cm(2) , 660 nm, 100 mW), together with an increased expression of Cyclin D1. Moreover, the immunoexpression of proteins related to epithelial proliferation and maturation (p63, CK10, CK14) all indicated a faster maturation of the migrating KCs in the LLLT-treated wounds. In that way, an improved epithelial healing was promoted by LLLT with the employed parameters; this improvement was confirmed by changes in the expression of several proteins related to epithelial proliferation and maturation. Immunofluorescent expression of cytokeratin 10 (red) and Cyclin D1 (green) in (A) Control keratinocytes and (B) Low-level laser irradiated cells. Blue color illustrates the nuclei of the cells (DAPI staining).

Effects of low-level laser irradiation on proliferation and functional protein expression in human RPE cells

Low-level laser irradiation (LLLI) modulates a set of biological effects in many cell types such as fibroblasts, keratinocytes, and stem cells. However, no study to date has reported the effects of LLLI on retinal pigment epithelia (RPE) cells. The aim of this study was to investigate whether LLLI could enhance the proliferation of RPE cells and increase the expression of RPE functional genes/proteins. Human ARPE-19 cells were seeded overnight and treated with 8 J/cm(2) of LLLI. Cell proliferation was measured by CCK8 assay and cell cycle distribution was evaluated by FACS. The transcription of cell cycle-specific genes and RPE functional genes was quantified by RT-PCR. Moreover, the expression of ZO-1 and CRALBP were evaluated by immunostaining. A dose of 8 J/cm(2) of LLLI significantly increased proliferation and promoted cell cycle progression while upregulating the transcription of CDK4 and CCND1 and decreasing the transcription of CDKN2A, CDKN2C, and CDKN1B in human ARPE-19 cells. Additionally, LLLI enhanced the expression of ZO-1 and CRALBP in human ARPE-19 cells. In conclusion, LLLI could enhance the proliferative ability of human ARPE-19 cells by modulating cyclin D1, CDK4, and a group of cyclin-dependent kinase inhibitors. It also could increase the expression of RPE-specific proteins. Thus, LLLI may be a potential approach for the treatment of RPE degenerative diseases.

In vitro study on the safety of near infrared laser therapy in its potential application as postmastectomy lymphedema treatment

Clinical studies demonstrated the effectiveness of laser therapy in the management of postmastectomy lymphedema, a discomforting disease that can arise after surgery/radiotherapy and gets progressively worse and chronic. However, safety issues restrict the possibility to treat cancer patients with laser therapy, since the effects of laser radiation on cancer cell behavior are not completely known and the possibility of activating postmastectomy residual cancer cells must be considered. This paper reports the results of an in vitro study aimed to investigate the effect of a class IV, dual-wavelength (808 nm and 905 nm), NIR laser system on the behavior of two human breast adenocarcinoma cell lines (namely, MCF7 and MDA-MB361 cell lines), using human dermal fibroblasts as normal control. Cell viability, proliferation, apoptosis, cell cycle and ability to form colonies were analyzed in order to perform a cell-based safety testing of the laser treatment in view of its potential application in the management of postmastectomy lymphedema. The results showed that, limited to the laser source, treatment conditions and experimental models used, laser radiation did not significantly affect the behavior of human breast adenocarcinoma cells, including their clonogenic efficiency. Although these results do not show any significant laser-induced modification of cancer cell behavior, further studies are needed to assess the possibility of safely applying NIR laser therapy for the management of postmastectomy lymphedema.

Cell cycle association and hypoxia regulation of excision repair cross complementation group 1 protein (ERCC1) in tumor cells of head and neck cancer

Excision repair cross complementation group 1 (ERCC1) is a key component of homologous recombination-based repair of interstrand DNA cross-links (ICLs). As a consequence, ERCC1 mediates resistance to mitomycin C (MMC) and platinum chemotherapeutic agents and may predict treatment failure. Clinical response to MMC or cisplatin (CDDP)-based radiochemotherapy (RCT) was assessed in 106 head and neck squamous cell carcinoma (HNSCC) patients and correlated with cell nuclear immunoreactivity of the mouse monoclonal (clone: 8 F1) ERCC1 antibody in tumor tissue samples. BEAS-2B epithelial and Detroit 562 pharyngeal squamous carcinoma cells were treated with CDDP, MMC, and 5-fluorouracil (5-FU) at 50 % growth inhibitory (IC-50) concentrations. ERCC1 protein synthesis was compared with cell cycle distribution using combined immunocytochemistry and flow cytometry. ERCC1 messenger RNA (mRNA) and protein expression was investigated in normoxic and hypoxic conditions in Detroit 562 cells. Clinically, the nonresponder revealed significantly lower HNSCC tissue ERCC1 immunoreactivity than the responder (p = 0.0064) or control normal mucosa, which led to further mechanistic investigations. In vitro, control cells and cells treated with cytotoxic agents showed increasing ERCC1 levels from the G1 through S and G2 phases of the cell cycle. In CDDP-treated cells, ERCC1 mRNA and protein expression increased. Under hypoxic conditions, ERCC1 gene expression significantly decreased. Although ERCC1⁺ cells show increased chemoresistance, they might be particularly radiosensitive, representing G2 cell cycle phase and less hypoxic. ERCC1 expression might be indirectly related with some conditions important for RCT treatment, but it is not a clear predictor for its failure in HNSCC patients.

Low-level laser therapy promotes proliferation and invasion of oral squamous cell carcinoma cells

Low-level laser therapy (LLLT) has been shown to be effective in promoting cell proliferation. There is speculation that the biostimulatory effect of LLLT causes undesirable enhancement of tumor growth in neoplastic diseases since malignant cells are more susceptible to proliferative stimuli. This study evaluated the effects of LLLT on proliferation, invasion, and expression of cyclin D1, E-cadherin, β-catenin, and MMP-9 in a tongue squamous carcinoma cell line (SCC25). Cells were irradiated with a diode laser (660 nm) using two energy densities (0.5 and 1.0 J/cm(2)). The proliferative potential was assessed by cell growth curves and cell cycle analysis, whereas the invasion of cells was evaluated using a Matrigel cell invasion assay. Expression of cyclin D1, E-cadherin, β-catenin, and MMP-9 was analyzed by immunofluorescence and flow cytometry and associated with the biological activities studied. LLLT induced significantly the proliferation of SCC25 cells at 1.0 J/cm(2), which was accomplished by an increase in the expression of cyclin D1 and nuclear β-catenin. At 1.0 J/cm(2), LLLT significantly reduced E-cadherin and induced MMP-9 expression, promoting SCC25 invasion. The results of this study demonstrated that LLLT exerts a stimulatory effect on proliferation and invasion of SCC25 cells, which was associated with alterations on expression of proteins studied.