| 1. |
- Rosell, Johan
(författare)
-
Long-term effects of adjuvant tamoxifen treatment on cardiovascular disease and cancer
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aims of this thesis were to investigate the long-term effects of adjuvant tamoxifen treatment on breast cancer recurrence and mortality, cardiovascular disease, and the incidence of secondary cancer.Between 1982 and 1992, postmenopausal patients with early stage breast cancer were included in a randomized clinical study of 2 or 5 years of postoperative tamoxifen therapy. The trial was planned by the Swedish Breast Cancer Group, and it included 4610 patients. Follow-up on causes of death, hospitalizations and secondary cancers were obtained from national population-based registries. All-cause mortality, breast cancer-specific mortality and mortality from coronary heart disease were decreased in the 5-year group, but the incidence of endometrial cancer was increased (Paper I). The incidence and mortality of cerebrovascular diseases were increased during the active treatment phase, and reduced after the active treatment (Paper II). Similar results were seen for subgroups of cerebrovascular diseases such as stroke and ischemic stroke. In the 5-year group, the morbidity from coronary heart disease was reduced during treatment but not after treatment was stopped (Paper III). This was the case also for heart failure and for atrial fibrillation/flutter. For secondary cancers the lung cancer risk was reduced, as well as the lung cancer mortality (Paper IV). An increased risk was observed for endometrial cancer, but appeared to decrease over time. The risk of contralateral breast cancer was reduced, with most of the reduction after treatment was stopped. For distance recurrences the risk was reduced both during treatment and a few years after treatment was stopped. The breast cancer mortality was also reduced, especially during the post-treatment phase.
|
|
| 2. |
- Bojmar, Linda
(författare)
-
Metastatic Mechanisms in Malignant Tumors
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ultimate cause of cancer related deaths is metastasis. This thesis is about three of the main human cancers; breast, colorectal and pancreatic cancer, that together account for more than 25% of the cancer-related deaths worldwide. The focus of the thesis is the spread of cancer, metastasis, and the aim was to investigate mechanisms that can be of importance for this process. We analyzed patient samples to validate the role of epithelialto-mesenchymal transition in vivo and found regulations of many related factors. However, these changes tend to fluctuate along the metastatic process, something which makes targeting complicated. We, moreover, focused on the influence of the tumor microenvironment for metastatic spread. In pancreatic cancer, the stroma constitutes the main part of many tumors. We analyzed the crosstalk between tumor and stromal cell and focused on the mediating inflammatory factor interleukin-1 (IL-1) and regulation of microRNAs. The results showed that the most commonly mutated factor in pancreatic cancer, KRAS, associates with the expression of IL-1 and subsequent activation of stromal cells. Blocking KRAS signaling together with IL-1 blockage give a more pronounced effect on in vitro proliferation and migration of cancer cells and suggests the use of a combination therapy. The cancer-associated activation of the stroma was found to be related to changes in microRNA expression. microRNA was analyzed separately in epithelial cells and stromal cells after microdissection of matched samples of primary and secondary tumors of breast and colorectal cancers. miR-214 and miR-199a were upregulated in stroma associated with progressive tumors and in pancreatic cancer stroma we could show that their expression alters the activation of stromal cells and thereby the growth and migratory ability of associated pancreatic tumor cells. In breast and colorectal cancers we found several common microRNAs to be up- or downregulated in line with progression. We could show that one of these candidates, miR-18a, had a prognostic value in metastatic breast cancer. To further develop these studies we analyzed this microRNA in circulating microvesicles, i.e. exosomes, and investigated their role in the preparation of a pre-metastatic niche. MicroRNAs are stable biomarkers in the circulation, especially protected in exosomes, which can moreover specifically deliver their message to recipient cells. These studies facilitate the understanding of metastatic behavior and suggest new targets to stop cancer metastasis.
|
|
| 3. |
- Djerf, Emelie, 1980-
(författare)
-
Studies on the effect of ErbB tyrosine kinase inhibitors on malignant melanoma growth and survival in vitro
- 2009
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Malignant melanoma has one of the fastest increasing incidences among the different types of cancerin the Western world. This raise can partly be ascribed to the change in sun habits that has takenplace during the last decades, since the major external risk factor for melanoma is exposure toultraviolet radiation. Patients with early stages of melanoma can often be cured by surgery, howeverfor patients suffering from metastatic melanoma there are only a few treatment options available.Unfortunately malignant melanoma is often resistant to radio-, bio- and chemotherapy and treatmentwith the currently most frequently used agent, dacarbazine, is characterized by a very low clinicalresponse rate. Therefore, there is an urgent need for new treatment strategies which can increase theoverall survival and cause less severe side effects.The aim of this thesis was to investigate the anti-tumor effect of two different tyrosine kinaseinhibitors (TKIs), gefitinib and canertinib, on two different human malignant melanoma (RaH3 andRaH5) cell lines. We investigate the effect of these two drugs on cell proliferation and survival andstudied the effect of gefitinib and canertinib on ErbB1-4 receptor phosphorylation, as well as Akt,Erk1/2 and Stat3 activity.Our results showed that phosphorylation of ErbB1, ErbB2 and ErbB3 decreased followingtreatment with both gefitinib and canertinib and that the subsequent downstream signaling via Akt,Erk1/2 and Stat3 was inhibited after TKI treatment. However, it was noted that the gefitinibinducedinhibition of Akt, and particularly Erk1/2, was transient and only a weak inhibition of Stat3phosphorylation was seen. Gefitinib treatment of the RaH3 and RaH5 cells resulted in anaccumulation of the cells in the G1 phase of the cell cycle without any induction of apoptosis.Canertinib caused a more pronounced inhibition of Akt, Erk1/2, and Stat3 phosphorylation thangefitinib. This might be one explanation to why canertinib induced apoptosis in RaH3 and RaH5cells whereas gefitinib only caused cell cycle arrest. In conclusion, gefitinib and canertinib displaypromising anti-tumor effects on ErbB expressing malignant melanoma and might be used in futurestudies in combination with conventional chemotherapy or other targeted therapies in the treatmentof malignant melanoma.
|
|
| 4. |
- Ellegård, Sander, 1985-
(författare)
-
HER2-positive breast cancer : Clinical and molecular aspects
- 2024
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundHuman Epidermal Growth Factor Receptor 2 (HER2)-positive breast cancer is notable for its aggressive behavior, however with the introduction of trastuzumab in the early 2000’s, prognosis has improved. This thesis investigates the efficacy of trastuzumab in real-world settings after its introduction and evaluates the prognostic value of molecular biomarkers, aiming to optimize treatment approaches and improve patient outcomes.Material and MethodsHER2-positive patients treated in the advanced and early stages of breast cancer were retrospectively identified using Swedish patient registries and through the review of medical records.Study I included 46 patients with advanced breast cancer treated with trastuzumab between 2000 and 2007. Immunohistochemical analysis of several proteins hypothesized to be involved in trastuzumab resistance were evaluated. Additionally, gene copy number variations were analyzed using droplet digital PCR.Study II include 599 patients who received adjuvant trastuzumab between 2006 and 2014 in the Southeastern health care region, in order to evaluate the implementation of trastuzumab after its approval and to evaluate patient outcomes with regard to clinicopathological variables.Study III conducted quantitative analyses of stromal tumor-infiltrating lymphocytes (sTILs) in patients with available tumor material from the same cohort identified in study II. Additionally, a case-control study of 21 cases with 21 matched controls treated with trastuzumab were analyzed with RNA-sequencing in order to identify important differentially expressed genes.ResultsStudy I demonstrated that trastuzumab treatment in a real-world setting had similar survival as in pivotal clinical trials. Additionally, high amplification of HER2 correlated with improved progression-free survival (PFS) and overall survival (OS) in advanced breast cancer patients and PTPN2 gain was correlated with reduced PFS and OS.Study II confirmed trastuzumab's efficacy in a large real-world cohort. Trastuzumab treatment, estrogen receptor (ER) status and number of metastatic lymph nodes were the most important prognostic factors for breast cancer-specific survival and distant recurrence-free survival.Study III identified a significant association between high levels of sTILs and improved overall survival. Additionally, several G-protein coupled receptors (GPCRs) involved in EGFR and Wnt signaling were found to be upregulated in cases vs controls.ConclusionsTrastuzumab maintains its efficacy in clinical practice, affirming its role in current treatment regimens for HER2-positive breast cancer. The findings support the prognostic significance of sTILs and suggest HER2-amplification levels as a relevant prognostic factor. We propose PTPN2 and several GPCRs as areas for future research.
|
|
| 5. |
- Hilborn, Erik, 1988-
(författare)
-
The role of the androgen receptor and hydroxysteroid 17β dehydrogenase in breast cancer : Impact on tamoxifen treatment
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The healthy breast is a tissue composed of centrally located milk producing glands connected to the nipple by ducts, surrounded by fat tissue and connective tissue. The growth of the breast is primarily mediated by the estrogens, while the androgens mediate tissue homeostasis and protect against growth signals. In breast cancer, the cells of the glands or ducts undergo malignant transformation, and start proliferating in an uncontrollable fashion. Breast cancer is the most common malignancy in women, and it is estimated that 10% of all women will be diagnosed with breast cancer during their life-time. The primary classification of breast cancer is based mainly on the expression of the estrogen receptor, and 70-80% of breast cancers are estrogen receptor positive, and are classified as luminal. The remaining breast cancers are classified into HER2 positive or triple negative breast cancer. Out of all breast cancers, ~80% are androgen receptor positive. This varies in different subtypes, however, with the highest expression in luminal and lowest expression in triple negative breast cancers. The role of androgen receptor varies depending on subtype. It is considered tissue-protective in luminal breast cancer, while it’s role in HER2 positive and triple negative breast cancers is less defined, but is generally considered to be associated with worse outcome. The primary treatment for breast cancer is surgery, followed by chemotherapy and/or radiotherapy to reduce the risk of recurrence. Treatment is also subtype specific, and luminal breast cancers in premenopausalwomen are treated using the estrogen receptor blocker (antagonist) tamoxifen, which blocks estrogen signaling. In postmenopausal women, luminal breast cancers are treated using tamoxifen or aromatase inhibitors, which prevent the formation of estrogen. The knowledge of which patient will respond and who will develop treatment resistance is of great importance, and the development of markers which can be analyzed prior to treatment in order to reduce the risk of unwanted side effects or complications is the focus of a large body of research. One of the primary goals of this thesis was to establish biomarkers for prognosis and tamoxifen treatment in breast cancer, and paper I, paper II and paper III address this aim.Steroid hormones, including estrogens and androgens, are normally synthesized from cholesterol in the adrenal gland, as well as in gender specific tissues such as ovaries in women or the testis or prostate in men. This synthesis takes place as a number of enzymatic conversions, mediated by several different enzymes, and the expression of these enzymes determines the final product of this conversion. In the adrenal gland, testis and prostate, androgens are the end-product, while the ovaries synthesize estrogens. These hormones are transported through the circulation, and upon reaching their target tissues, they mediate their effect. The impact of the steroids on their destination tissue is dependent on their relative concentration and exposure time, which in turn is dependent on the amount in the circulation, but also on the presence of local steroid converting enzymes, which are present in most tissues. The enzymes of the hydroxysteroid 17β dehydrogenase family are present in most tissues, primarily the oxidative member hydroxysteroid 17β dehydrogenase type 2, which facilitate the conversion of estrogens and androgens to the less active forms, thus protecting the tissues from their effect. In breast cancer, the reductive form, hydroxysteroid 17β dehydrogenase type 1 is often up-regulated, and mediates increased activation of estrogens, resulting in increased estrogen signaling, which results in increased proliferation and growth. The second goal of this thesis was to further study the role of hydroxysteroid 17β dehydrogenase enzymes in breast cancer, and paper I and paper IV address different aspects of their role in breast cancer.Following reduction of the expression of hydroxysteroid 17β dehydrogenase type 14, an oxidative member of the family, in breast cancer, the expression of C-X-C ligand 10 was found to be altered. In paper I, in order to determine the role of C-X-C ligand 10 and C-X-C receptor 3 in breast cancer, their expression was quantified using immunohistochemistry in breast cancer patients randomized to tamoxifen or no endocrine treatment irrespectively of estrogen receptor status. The expression of C-XC ligand 10 and C-X-C receptor 3 was found to be associated with increased tamoxifen treatment benefit in the estrogen receptor positive group of patients, indicating that they could be useful markers for determining which patient would respond well to this treatment. Further, C-X-C receptor 3 expression was associated with worse outcome in patients who did not receive tamoxifen, and could be a potential target for inhibitors in order to improve patient outcome. The role of the androgen receptor in breast cancer was evaluated. In paper II the expression was quantified using immunohistochemistry in the same cohort as in paper I. We show that in patients with estrogen receptor negative tumors, the androgen receptor is associated with worse outcome. In patients with high tumoral androgen receptor expression, tamoxifen signaling results in significant improvement in outcome, despite lack of the estrogen receptor. The opposite was observed in patients without tumoral androgen receptor expression, and tamoxifen treatment was associated with adverse outcome. Similar findings were made in the triple negative cases. In the luminal cases, the androgen receptor does not provide further information pertaining to outcome. In paper III we evaluated the role of mutations in the androgen receptor in the cohort of estrogen receptor-negative and androgen receptorpositive cases from paper II. The role of mutations in the androgen receptor appear to have a modest role in regard to patient outcome, but rs17302090 appear associated with tamoxifen treatment benefit. The modulation of the members of the hydroxysteroid 17β dehydrogenase in breast cancer is associated with changes in the local steroid balance, and has been associated with worse outcome and changes in the response to tamoxifen. Further, the inhibition of hydroxysteroid 17β dehydrogenase type 1 has been proposed as an alternate treatment for breast cancer, but no inhibitors are currently used in the clinic. In paper IV, we evaluated several different mechanisms by which the expression of hydroxysteroid 17β dehydrogenase type 1 and type 2 are modulated in breast cancer. We show that the most potent estrogen estradiol, in an estrogen receptor dependent fashion, can result in decreased hydroxysteroid 17β dehydrogenase type 1 expression, and a short term reduction in type 2 expression or long term increased type 2 expression. We also show that the most potent androgen, dihydrotestosterone, can increase hydroxysteroid 17β dehydrogenase type 2 expression, but has limited impact on hydroxysteroid 17β dehydrogenase type 1. Further, we show that a number of genes involved in breast cancer, and microRNA are involved in modulating the expression of the hydroxysteroid 17β dehydrogenase type 1 and type 2 in breast cancer. These findings could potentially be used as an alternative to inhibitors, and help modulate the steroidal balance in target tissue.
|
|
| 6. |
- Karlsson, Elin, 1984-
(författare)
-
Clinical potential of the mTOR effectors S6K1, S6K2 and 4EBP1 in breast cancer
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The prognosis of patients diagnosed with breast cancer has been considerably improved in the latest 25 years, as a result of continuous development of diagnostics and treatment regimens. Though, tumour diseases, for woman mainly lung cancer and breast cancer, still constitute of the most common causes of death in developed countries, following heart diseases. A future utopia is to develop more individualised therapy strategies, to further increase breast cancer survival, but also to decrease the risk of severe side-effects of unnecessary treatments.Normal mammary gland development is regulated by a complex interplay between growth factors and hormones, mainly oestrogen and progesterone, in different cell types. Breast cancer origin and progression is assumed to result from an imbalance in this interplay, leading to the so called “Hallmarks of cancer”, including unlimited cellular proliferation. A central hub in the regulation of proliferation is the intracellular mTOR signalling pathway. Antioestrogen therapy is widely used in breast cancer clinics, however resistance towards this treatment is a remaining problem, and overactivation of mTOR may be one reason behind. A new treatment regimen constituting a combination of mTOR inhibitors with endocrine therapy was recently clinically approved for advanced breast cancers. Although significant benefit for this combination treatment is evident for some patients, counteracting feedback mechanisms are assumed to diminish the effects.The work presented in this thesis focuses on the genes S6K1, S6K2 and 4EBP1 which are main effectors of the intracellular mTOR signalling pathway and thereby secondary targets of the mTOR inhibitors. Our results suggests that the gene amplification status, expression levels of the corresponding mRNA and protein of S6K1, S6K2 and 4EBP1 as well as their cellular localisation may be used to predict breast cancer outcome and the benefit from antioestrogen treatments. These factors are indicated to play separate roles in different subtypes of breast cancer, and specific targeting of S6K1 and S6K2 may be valuable in different tumour subtypes, and in comparison to present day’s mTOR inhibitors, further promote individualised therapies, and thereby increase breast cancer survival.
|
|
| 7. |
- Severinsson, Emelie
(författare)
-
Experimental studies on ErbB targeted therapy in malignant melanoma
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Malignant melanoma has one of the fastest increasing incidences among the different types of cancer in the Western world. This raise can partly be ascribed to the change in sun habits that has taken place during the last decades, since the major external risk factor for melanoma is exposure to ultraviolet radiation. In the case of patients with early stages of melanoma, the prognosis is usually good and the disease may be cured by surgery alone. However, with conventional anti-cancer treatments, patients diagnosed with unresectable or metastatic melanoma have a very low 5-year survival rate ranging from less than 10 percent to about 20 percent, depending on the location and extent of metastatic spread. Despite the development of novel promising targeted drugs, such as the immunomodulating antibody ipilimumab and the B-raf inhibitor vemurafenib, that have been shown to significantly extend patient survival, there is still an urgent need for new and improved treatment strategies which can further increase the survival of patients with advanced malignant melanoma.The aim of this thesis was to investigate the anti-tumor effect of two different tyrosine kinase inhibitors (TKIs), gefitinib and canertinib, on human malignant melanoma cell lines with wild-type BRAF and NRAS. We investigated the effect of these two drugs on cell proliferation, survival and on the ErbB1-4 receptor phosphorylation, as well as the downstream signaling molecules Akt, Erk1/2 and Stat3. We also established a melanoma cell line resistant to gefitinib treatment and studied the resistance mechanisms developed by the cells.The aim of this thesis was to investigate the anti-tumor effect of two different tyrosine kinase inhibitors (TKIs), gefitinib and canertinib, on human malignant melanoma cell lines with wild-type BRAF and NRAS. We investigated the effect of these two drugs on cell proliferation, survival and on the ErbB1-4 receptor phosphorylation, as well as the downstream signaling molecules Akt, Erk1/2 and Stat3. We also established a melanoma cell line resistant to gefitinib treatment and studied the resistance mechanisms developed by the cells.In conclusion, gefitinib and canertinib display promising anti-tumor effects on ErbB-expressing malignant melanoma and might be used in future studies in combination with conventional chemotherapy or other targeted therapies in the treatment of malignant melanoma patients not harboring BRAF or NRAS mutations.
|
|
| 8. |
- Sivik, Tove, 1980-
(författare)
-
Elucidating the role of 17β hydroxysteroid dehydrogenase type 14 in normal physiology and in breast cancer
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Oestrogens play key roles in the development of the majority of breast tumours, a fact that has been exploited successfully in treating breast cancer with tamoxifen, which is a selective oestrogen receptor modulator. In post-menopausal women, oestrogens are synthesised in peripheral hormone-target tissues from adrenally derived precursors. Important in the peripheral fine-tuning of sex hormone levels are the 17β hydroxysteroid dehydrogenases (17βHSDs). These enzymes catalyse the oxidation/reduction of carbon 17β of androgens and oestrogens. Upon receptor binding, the 17β-hydroxy conformation of androgens and oestrogens (testosterone and oestradiol) triggers a greater biological response than the corresponding keto-conformation of the steroids (androstenedione and oestrone), and the 17βHSD enzymes are therefore important mediators in pre-receptor regulation of sex hormone action.Breast tumours differ substantially with regards to molecular and/or biochemical signatures and thus clinical courses and response to treatment. Predictive factors, which aim to foretell the response of a patient to a specific therapeutic intervention, are therefore important tools for individualisation of breast cancer therapy. This thesis focuses on 17βHSD14, which is one such proposed marker, aiming to learn more of properties of the enzyme in breast cancer as well as in normal physiology. We found that high 17βHSD14 levels were correlated with clinical outcome in two separate subsets of breast tumour materials from trials evaluating adjuvant tamoxifen therapy. Striving to understand the underlying mechanisms, immunohistochemical 17βHSD14 expression patterns were analysed in a large number of human tissues using an in-house generated and validated antibody. The 17βHSD14 protein was expressed in several classical steroidogenic tissues such as breast, ovary and testis which supports idea of 17βHSD14 being an actor in sex steroid interconversion. Furthermore, using a radio-high pressure liquid chromatography method, cultured cells transiently expressing HSD17B14 were found to oxidise both oestradiol and testosterone to their less potent metabolites oestrone and androstenedione respectively. The evaluation of a mouse model lacking Hsd17b14 revealed a phenotype with impaired mammary gland branching and hepatic vacuolisation which could further suggest a role for 17βHSD14 in oestrogen regulation.Although other mechanisms of the enzyme cannot be ruled out, we suggest that 17βHSD14 relevance in tamoxifen-treated breast cancer is related to oestradiol-lowering properties of the enzyme which potentiate the anti-proliferative effects of tamoxifen. Translating into the clinical setting, patients with oestrogen receptor positive tumours expressing low levels of oestradiol-oxidising enzymes such as 17βHSD14 would likely receive more clinical benefit from alternative treatments to tamoxifen such as aromatase inhibitors or in the future possibly inhibitors of reductive 17βHSD-enzymes.
|
|
| 9. |
- Bostner, Josefine, 1981-
(författare)
-
The Akt/mTOR Pathway and Estrogen Receptor Phosphorylations : a crosstalk with potential to predict tamoxifen resistance in breast cancer
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Estrogen receptor α content is the primary breast cancer biomarker distinguishing the patients responsive from the non-responsive to endocrine treatments. Tamoxifen is an estrogen competitor with large potential to treat breast cancer patients and prolongs time to recurrence. Despite the estrogen receptor positivity and tamoxifen treatment, many women face recurrence of the disease. An important mechanism of resistance to endocrine treatments is upregulated growth factor signaling, and the subsequent effect on the estrogen receptor, rendering an active receptor that stimulates cell proliferation or reduced estrogen-receptor dependence.This thesis concerns the investigation of biomarkers, as a complement to the existing markers, for determining optimal treatment for patients with primary invasive breast cancer. Randomized patient tumor materials were used in order to measure variations in gene copies, proteins, and protein phosphorylations and to further relate these variations to time-to-recurrence. Endocrine untreated groups within the patient tumor sets gave us the opportunity to study the prognostic potential of selected markers and to compare tamoxifen-treated patients with endocrine untreated, thus obtaining a treatment-predictive value of each marker or marker combination.In endocrine-dependent cancer the 11q13 chromosomal region is frequently amplified, harboring the genes encoding the cell cycle stimulator cyclin D1 and the estrogen receptor phosphorylating kinase Pak1, respectively. Amplification of the genes was associated with reduced time-torecurrence, indicating a prognostic value, whereas PAK1 gene amplification predicted reduced response to tamoxifen treatment. Moreover, the protein expression of Pak1 tended to predict treatment response, which led to the investigation of this protein in a larger cohort. Together with one of its targets, the estrogen receptor phosphorylation at serine 305, Pak1 predicted reduced response to tamoxifen treatment when detected in the nucleus of tumor cells, suggesting activation of this pathway as a mechanism for tamoxifen-treatment resistance. The estrogen receptor is phosphorylated by several growth factor stimulated kinases. The role of serine-167 phosphorylation has been debated, with inconsistent results. To study the biomarker value of this site the upstream activity of Akt, mTOR, and the S6 kinases were analyzed individually and in combinations. As a prognostic factor, serine 167 indicated an improved breast cancer survival, and as a treatment predictive factor we could not detect a significant value of serine 167 as a single marker. However, in combination with serine 305, and Akt/mTOR-pathway activation, the response to tamoxifen treatment was reduced. The mTOR effector protein S6K1 was found to be associated with HER2 positivity and a worse prognosis. In the group of patients with S6K1 accumulation in the tumor cell nuclei, treatment did not prolong time-to-recurrence, similarly as observed with expression of active S6 kinases. In vitro, a simultaneous knockdown of the S6 kinases in estrogen receptor-positive breast cancer cells resulted in G1 arrest, and tamoxifen-induced G1 arrest was in part S6 kinase dependent.The results presented herein suggest biomarkers that would improve treatment decisions in the clinic, specifically for estrogen receptor-positive breast cancer and tamoxifen treatment but in a broader perspective, also for other endocrine treatments and targeted treatments.
|
|
| 10. |
- Lysiak, Malgorzata, 1989-
(författare)
-
Biomarkers In Brain Tumors With Focus On Glioblastoma
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The primary brain tumors, gliomas, are not very common but they are deadly. Each year in Sweden around 500 patients will be diagnosed with a glioma and unfortunately most of them will have the most aggressive type, glioblastoma (GBM). Median survival, even if treated, is poor (14-17 months). Males are diagnosed up to 60% more often than females and they often have a worse prognosis. GBM affects mainly older patients and treatment includes radiochemotherapy with temozolomide (TMZ). The only known predictive biomarker for TMZ treatment is methylation of the O6-methylguanine DNA methyltransferase (MGMT) promoter and patients with methylated MGMT have better outcomes. There is a great need for biomarkers to decipher existing sex differences and others that identify patients that will benefit from radiotherapy (RT) or TMZ despite of unmethylated MGMT. Papers I-III are focused on investigating sex differences in GBM and in Paper IV we examined the methylation-based biomarkers used in diagnostics, on patients from the Nordic trial with exceptionally good and poor survival when treated with TMZ or RT. Loss of the Y chromosome (LOY) in male’s blood cells is associated with aging and, among other diseases, with cancer. We looked at 10 genes located on chromosome Y in 105 males with GBM treated with TMZ concomitant with RT and found that they are often deleted. Detected LOY, as well as deletion of the sex determining region Y (SRY) gene were associated with shorter overall survival. Low SRY gene expression analyzed in an additional cohort of 219 samples from The Cancer Genome Atlas (TCGA) was also associated with a shorter survival.In Paper II we re-analyzed data from three cohorts to compare the frequency of MGMT methylated tumors in males and females and investigated whether sex is an important factor associated with patient’s survival. This was done in a GBM cohort from the randomized, phase 3 Nordic trial, which included patients 60 years or older, treated with standard RT (60Gy) vs. hypofractionated RT vs. TMZ given in up to six 4 weekly cycles; in a population-based cohort, treated with TMZ concomitant with RT and an excerpt of the TCGA cohort of patients treated with different modalities. In all three cohorts there was a higher fraction of MGMT methylated tumors in females and MGMT methylation was predictive of longer survival for those treated with an alkylating agent, such as TMZ.The third study investigated the androgen receptor (AR), located on chromosome X as a potential sex susceptibility factor for GBM. We found that the gene encoding for AR can be amplified or deleted in GBM, and these changes are more common in females. The AR gene expression was enhanced in GBM but did not differ between sexes. At the same time, in a separate analysis for males and females, we found that high AR expression is associated with shorter survival in females and longer survival in males Also, the methylation sites in the AR promoter that correlated with gene expression are sex specific. In Paper IV we included 59 patients from the Nordic trial, equally divided by the treatment arms and MGMT methylation status, with good prognostic factors and with long or short survival. We performed genome-wide methylation analysis and identified differentially methylated sites between those with long and short survival for the TMZ treated, MGMT methylated samples, as well as the 60Gy, MGMT unmethylated and 34Gy MGMT methylated samples. This small pilot study was unable to discern any differentially methylated sites in TMZ treated samples with unmethylated MGMT, associated with long or short survival. By using a methylation-based diagnostic classifier, we were able to detect a misclassified sample that was not a GBM. Lastly, we calculated so called ‘epigenetic age’ of the tumor tissue based on the methylation data and using three different algorithms and found that in all treatment groups short-term survivors tended to have lower epigenetic age, though these results were not significant and need verification in a larger cohort.In summary, this thesis advances our knowledge on the molecular differences between male and female GBM and the association between these alterations and patients’ survival. Our results also suggest that there are potential methylation-based biomarkers apart from the MGMT promoter methylation, that can be used to distinguish between patients with good and poor prognosis, for instance, the epigenetic age.
|
|
