| 1. |
|
|
| 2. |
- Fessé, Per, 1973-
(författare)
-
Epidermal Melanocyte Response to Radiotherapy
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cutaneous interfollicular melanocytes protect the skin from UV-radiation (UVR), and their response to UVR is well established. To date, the response activated in melanocytes by repeated genotoxic insults from radiotherapy (RT) has not been explored. Assuming that the molecular pathways involved in the melanocyte response to UVR are similar upon ionizing radiation, the aim of this work was to examine the effects of RT concerning UVR-response proteins and resistance to DNA damage to reveal mechanisms behind hyperpigmentation and depigmentation caused by RT. The results are based on immunostained tissue sections of 530 not sun-exposed skin punch biopsies. These are collected before, during, and after the end of adjuvant RT from the thoracic wall of breast cancer patients and the hip region of prostate cancer patients receiving curative RT. Fractionated RT with daily doses between 0.05 and 2.0 Gy, as well as hypofractionation and accelerated fractionation were investigated. Based on this clinical assay sterilizing the hair follicles, excluding migration of immature melanocytes from the bulge, it was ensured that interfollicular melanocytes are an autonomous self-renewing cell population with cells presenting different degrees of differentiation of which one fourth is immature; the melanocytes divide rarely and are absolute radioresistant to any dose schedule of RT applied, keeping the number of melanocytes intact. Hyperradiosensitivity to dose fractions of 0.05 to 0.3 Gy is observed for DNA double strand breaks (DSBs), differentiation and anti-apoptotic signaling. Proliferation is not stimulated and apoptosis is negligible upon exposure to RT, and also post-treatment. Melanocyte differentiation is maintained during RT, but dedifferentiation occurs after RT ends. The expected activation of the p53/p21 signaling upon RT appears in keratinocytes but is attenuated in melanocytes. A new observation is that melanocytes constitutively express BMI1, further upregulated upon irradiation, indicating that melanocytes have stem cell properties, which suggest that BMI1 prevents apoptosis, terminal differentiation and premature senescence and likely allows dedifferentiation by suppressing the p53/p21-mediated response to genotoxic damage, in addition to the repression of p16 and ARF. Melanocytes exhibit and accumulate a higher amount of DSBs during the RT period compared to keratinocytes, indicating reduced repair capacity of DSBs in melanocytes. Thus, only efficient pro-survival mechanisms can explain the melanocyte radioresistance regarding cell death. The findings in this thesis suggest that melanocytes are protected by activation of the BMI1-NF-kappa/β-CXCL8/CXCR2 pathway, in addition to upregulation of Bcl-2 by melanocyte-specific MITF (microphthalmia-associated transcription factor).
|
|
| 3. |
|
|
| 4. |
- Pettersson, Anna, 1979-
(författare)
-
Diet and Gastrointestinal Symptoms in Patients with Prostate Cancer Treated with Radiotherapy
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Objective The main objective of this thesis was to explore the effects of diet on gastrointestinal symptoms in prostate cancer patients treated with local curative radiotherapy, by evaluating dietary intake prior to treatment (Study I), the psychometric properties of a new questionnaire on patient-reported gastrointestinal side effects (Study II), and the effect of a dietary intervention on acute and long-term gastrointestinal symptoms up to 2 years after radiotherapy completion (Study III-IV).Methods A total of 130 men with localized prostate cancer referred to dose-escalated radiotherapy (ED2 87-102 Gy, α/β=3 Gy) were recruited to a dietary intervention trial. Patients were randomized to receive either standard care plus the dietary intervention of a fibre- and lactose-restricted diet (intervention group, IG; n=64) or standard care alone (standard care group, SCG; n=66). Data on gastrointestinal symptoms and dietary intake were collected pre-treatment and at seven time points during a follow-up period of 26 months.Results Prior to treatment, grain products and milk products were major sources of energy. Unbalanced fatty acid intake and low intake of selenium were observed (Study I). Validation of the Gastrointestinal Side Effects Questionnaire (GISEQ) revealed satisfactory internal consistency, moderate concurrent validity and adequate responsiveness (Study II). There were no significant effects of the intervention on acute or long-term gastrointestinal symptoms, but a tendency towards lower prevalence and severity of bloating and diarrhoea in the IG compared to the SCG during radiotherapy. Gastrointestinal symptoms were predominantly mild, and the frequency of clinically relevant symptoms was merely a few percent. Dietary adherence in the IG was initially good, but tended to decline beyond 12 months post-radiotherapy (Study III-IV).Conclusions A fibre- and lactose-restricted diet was not superior to the habitual diet in reducing gastrointestinal symptoms in patients undergoing high-dose, small-volume radiotherapy for localized prostate cancer. The GISEQ enables assessment of patient-perceived change in symptoms, but further work is needed to strengthen its psychometric qualities. It is suggested that continued research in this area target patient categories referred to irradiation of larger pelvic volumes with a higher risk of gastrointestinal symptoms, and that dietary interventions incorporate established strategies to enhance adherence and effectiveness.
|
|
| 5. |
|
|
| 6. |
- Qvarnström, Fredrik, 1976-
(författare)
-
DNA Damage Response of Normal Epidermis in the Clinical Setting of Fractionated Radiotherapy : Evidence of a preserved low-dose hypersensitivity response
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Investigations of DNA damage response (DDR) mechanisms in normal tissues have implications for both cancer prevention and treatments. The accumulating knowledge about protein function and molecular markers makes it possible to directly trace and interpret cellular DDR in a tissue context. Using immunohistochemical techniques and digital image analysis, we have examined several principal DDR events in epidermis from patients undergoing fractionated radiotherapy. Acquiring biopsies from different regions of the skin provides the possibility to determine in vivo dose response at clinically relevant dose levels throughout the treatment. A crucial event in cellular DDR is the repair of DNA double strand breaks (DSBs). These serious lesions can be directly visualised in cells by detecting foci forming markers such as γH2AX and 53BP1. Our results reveal that DSB-signalling foci can be detected and quantified in paraffin-embedded tissues. More importantly, epidermal DSB foci dose response reveals hypersensitivity, detected as elevated foci levels per dose unit, for doses below ~0.3Gy. The low-dose hypersensitive dose response is observed throughout the treatment course and also in between fractions: at 30 minutes, 3 hours and 24 hours following delivered fractions. The dose response at 24 hours further reveals that foci levels do not return to background levels between fractions. Furthermore, a low-dose hypersensitive dose response is also observed for these persistent foci. Investigations of end points further downstream in the DDR pathways confirmed that the low-dose hypersensitivity was preserved for: the checkpoint regulating p21 kinase inhibitor; mitosis suppression; apoptosis induction and basal keratinocyte reduction. Our results reveal preserved low-dose hypersensitivity both early and late in the DDR pathways. A possible link between the dose-response relationships is therefore suggested. The preserved low-dose hypersensitivity is a cause for re-evaluation of the risks associated with low-dose exposure and has implications for cancer treatments, diagnostics and radiation protection.
|
|
| 7. |
|
|
| 8. |
- Simonsson, Martin, et al.
(författare)
-
Epidermal keratinocyte loss in response to daily 2 Gy fractions for 5 weeks of radiotherapy is associated with DSB-foci, growth arrest, apoptosis and lack of accelerated repopulation
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background and purpose: Tissue-sparing due to repopulation is expected to occur in epithelial cell populations during a course of fractionated radiotherapy (RT). Recently, we established, in the clinical setting of RT, the dose response relationship of subtherapeutic doses in terms of epidermal keratinocyte loss in the basal layer throughout 7 weeks of RT. Surprisingly, in the case of daily dose fractions of 1.10Gy, the keratinocyte loss per dose unit increases over the last 4 weeks of the treatment period rather than being constant or decreasing. The aim of the present study is to elaborate on the issue of germinal keratinocyte response to daily dose fractions of 2.0Gy for 5 weeks. Here, we present assessments of keratinocyte loss, DSB foci, growth arrest, mitosis and apoptosis using methods earlier described by us. Materials and Methods: In total 240 skin punch biopsies, collected from 31 breast cancer patients, before, during and after postmastectomy radiotherapy given to the thoracic wall with daily 2.0Gy fractions for 5 weeks, were investigated. The dose response for basal keratinocyte density of the interfollicular epidermis was determined. The DNA damage response of keratinocytes was studied by immunostaining for molecular markers of DNA DSBs, growth arrest, mitosis and cell death using 53BP1, p21, phospho-H3 and γH2AX (apoptosis), respectively. The stainings of keratinocytes were counted manually or by digital image analysis. Results: The dose-response relationship for the loss of basal keratinocytes over 5 weeks of RT revealed a biphasic shape. An initial radioresistant phase was followed by an increase in radiosensitivity in the second part of RT. The rate of keratinocyte loss reflected the significant changes determined by 53BP1 and γH2AX foci 30 minutes after dose fractions over the treatment period. The highest induction of DSB foci per cell was observed towards the end of treatment. The increase in the fraction of p21 stained cells was also more prominent during the second half of the treatment as compared to the first period of RT. The apoptotic frequency was generally low but increased dramatically towards the end of RT. The mitotic cell number was significantly suppressed over 5 weeks, and did not recover during the weekend treatment-gaps. Notably, the mitotic rate increased more than threefold compared to unexposed skin, 2 weeks after the end of RT, followed by a rapid decline one week later. Conclusion: The dose response for germinal keratinocyte loss as a result of daily dose fractions of 2.0Gy over 5 weeks treatment deviates significantly from an exponential curve fit. The effectiveness of each dose fraction was less in the first half of the treatment when compared with the second half. No accelerated repopulation could be revealed over the 5 weeks, but was evident after completion of radiotherapy. The changes in keratinocyte response were associated with changes in induction of DSB foci and p21 protein expression, as well as apoptotic events over the treatment period. In particular, we highlight the existence of pre-mitotic apoptosis, which increased significantly towards the end of 5 weeks RT. These findings suggest that it is necessary to reconsider the current conceptions regarding DNA repair, cell-cycle redistribution and repopulation of normal epithelial cells to a long-lasting courses of fractionated radiotherapy.
|
|
| 9. |
- Simonsson, Martin, 1975-
(författare)
-
Quantification of Radiation Induced DNA Damage Response in Normal Skin Exposed in Clinical Settings
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The structure, function and accessibility of epidermal skin provide aunique opportunity to study the DNA damage response (DDR) of a normaltissue. The in vivo response can be examined in detail, at a molecularlevel, and further associated to the structural changes, observed at atissue level. We collected an extensive skin biopsy material frompatients undergoing fractionated radiotherapy for 5 to 7 weeks. Several end-points inthe DDR pathways were examined before, during and after the treatment. Quantification of DNA double strand break (DSB) signalling focirevealed a hypersensitivity to doses below 0.3Gy. Furthermore, aconsiderable amount of foci persisted between fractions. The low dosehypersensitivity was observed throughout the treatment and was alsoobserved for several key parameters further downstream in the DDR-pathway, such as p21-associated checkpoint activation, apoptosisinduction and reduction in basal keratinocyte density (BKD).Furthermore, for dose fractions above 1.0 Gy, a distinct acceleration inDDR was observed half way into treatment. This was manifested as anaccelerated loss of basal keratinocytes, mirrored by a simultaneousincrease in DSBs and p21 expression. Quantifications of mitotic events revealed a pronounced suppression ofmitosis throughout the treatment which was clearly low dosehypersensitive. Thus, no evidence of accelerated repopulation could beobserved for fraction doses ranging from 0.05 to 2Gy. Our results suggest that the keratinocyte response primarily isdetermined by checkpoints, which leads to pre-mitotic cell elimination by permanent growth arrest and apoptosis. A comparison between the epidermal and dermal sub-compartments revealsa consistent up-regulation of the DDR response during treatment. Adifference was however observed in the recovery phase after treatment,where miR-34a and p21 remain up-regulated in dermis more persistentlythan in epidermis. Our observations suggest that the recovery phaseafter treatment can provide important clues to understand clinicalobservations such as the early and late effects observed in normaltissues during fractionated radiotherapy.
|
|
| 10. |
|
|
