7 polska forskare + 1 från Lettland har utfört,enligt mig, en ambitiös,avancerad och mkt ovanlig studie kring bröstcancer.Man har studerat bröstcancerceller som behandlats med det kända cancerläkemedlet Doxorubicin,som finns under ex varumärket Adriamycin.Som jag förstår det har man sen studerat de behandlade cancercellerna när de är på "återgång".Eller som man skriver i studien "åldrande".
Sen kommer vi in på det riktigt avancerade !
Man har studerat dessa cancerceller ner på molekylnivå samt DNA-nivå.Studerat cellernas molekyler,vilka som påverkats av cancerläkemedlet och är på "återgång" OCH de molekyler som INTE visar tecken på att läkemedlet haft effekt.Man ville ha svar på varför och hur stor risk att dessa Oeffekterade molekyler i cellerna började om på nytt och därigenom orsakade ett nytt utbrott av cancertillväxt.Återfall som man beskriver det i studien.Forskarna skriver redan i början i abstractet att studier om detta är " poorly explored issue ".Alltså att det inte bedrivits nån forskning om det i nån större omfattning.
Bara av den anledningen är forskarnas insatser imponerande,att de utforskat händelseförlopp i en behandlad bröstcancer och sökt svar på varför vissa celler ändå utvecklar sig till en ny bröstcancer.En kunskap som är mer eller mindre obefintlig idag.För det ska de ha en stor eloge.
Men till forskningsrapporten då.
Abstract
The induction of senescence/polyploidization and their role in cancer
recurrence is still a poorly explored issue. We showed that MDA-MB-231
and MCF-7 breast cancer cells underwent reversible
senescence/polyploidization upon pulse treatment with doxorubicin (dox).
Subsequently, senescent/polyploid cells produced progeny (escapers)
that possessed the same amount of DNA as parental cells. In a
dox-induced senescence/polyploidization state, the accumulation of
autophagy protein markers, such as LC3B II and p62/SQSTM1, was observed.
However, the senescent cells were characterized by a very low rate of
new autophagosome formation and degradation, estimated by autophagic
index. In contrast to senescent cells, escapers had a substantially
increased autophagic index and transcription factor EB activation, but a
decreased level of an autophagy inhibitor, Rubicon, and autophagic
vesicles with non-degraded cargo. These results strongly suggested that
autophagy in escapers was improved, especially in MDA-MB-231 cells. The
escapers of both cell lines were also susceptible to dox-induced
senescence. However, MDA-MB-231 cells which escaped from senescence were
characterized by a lower number of γH2AX foci and a different pattern
of interleukin synthesis than senescent cells. Thus, our studies showed
that breast cancer cells can undergo senescence uncoupled from autophagy
status, but autophagic flux resumption may be indispensable in cancer
cell escape from senescence/polyploidy.
Introduction
Despite
the spectacular progress in cancer treatment made during recent years,
some types of aggressive cancer are still able to spread easily and
become resistant to anticancer treatment. One of the reasons for this
could be the phenomenon of therapy-induced senescence (TIS).
TIS, which halts cancer cell proliferation instead of inducing cell death, became a desirable outcome of cancer treatment.
However, it eventually turned out that the senescence of cancer cells
can have an adverse effect of radio/chemotherapy. Indeed, senescent
cells secrete many factors that modify the microenvironment, which in
turn favor cancer development.
Moreover, the senescence of cancer cells can be reversible.
Interestingly, it seems that the reversibility of cancer cell
proliferation arrest is associated with their therapy-induced
polyploidization.
The progeny of polyploid senescent cells regain the ability to
proliferate, together with depolyploidization. Thus, TIS could represent
a mechanism of evasion from the toxicity of chemotherapy and radiation,
facilitating cancer recurrence.
Senescent
cancer cells, beside division arrest and secretory activity, known as
the senescence-associated secretory phenotype (SASP), are, similarly to
senescent normal cells, characterized by many other features, such as
the increased activity of senescence-associated β-galactosidase
(SA-β-gal), lipofuscin and lipid droplet accumulation, altered
morphology (flattening and increased granularity), an increased level of
cyclin-dependent kinase inhibitors, such as p16INK4A and p21WAF1/CIP1, increased lysosomal mass, morphologically and functionally altered mitochondria and DNA double-strand breaks (DSBs). The latter induces the so-called DNA damage response (DDR) signaling pathway.
The most frequently analyzed key proteins of the DDR, which include DNA
DSB sensors, mediators and executors, are: γH2AX, 53BP1, p-ATM, p-ATR,
p-p53 and p-CHK2.
Cellular senescence, characterized by increased metabolism, is closely
interrelated with autophagy, however, senescence may be a result of
autophagy impairment or, on the contrary, senescence may lead to
autophagy dysfunction. Autophagy in senescent cells, especially cancer
senescent cells, is highly dependent on the cell type and context.
It has been postulated by Erenpreisa et al.
that transiently senescent cancer cells acquire additional DNA repair
capacity through mitotic slippage and entering a sequence of ploidy
cycles, which facilitate the repair and sorting of damaged DNA,
ultimately promoting the genesis of mitotically competent daughter cells
following final depolyploidization. It has been stated that autophagy
is required to fuel this process.
Autophagy
is a catabolic process in which macromolecules and organelles are
degraded and recycled, thus providing metabolites to maintain the energy
supply in the cell. A characteristic feature of macroautophagy (herein
referred to as autophagy) is the formation of vesicles, called
autophagosomes, that enclose the degradation-bound cargo and,
subsequently, fuse with lysosomes, giving rise to autolysosomes, wherein
the cargo is degraded and recycled. The formation of the autophagosome
includes phagophore nucleation, elongation and vesicle completion, which
are tightly regulated by various autophagy-related proteins, e.g., the
ULK1/2 complex, the class III PtdIns3K complex and LC3-II.
Autophagy is regulated at each stage, i.e., initiation, vesicle fusion
or cargo degradation, by external factors or by endogenous modulators,
e.g., Rubicon, the protein present in the Beclin complex, and inhibiting
autophagy.
As autophagy is a highly dynamic process, for proper estimation of
autophagy efficiency, it is crucial to measure the autophagic flux,
which determines the degradation activity.
Although the modulation of autophagy is a very important part of cancer therapy,
no therapies are currently available that specifically focus on
autophagy modulation. Moreover, there are many controversies in the
literature concerning the role of autophagy in cancer cell senescence
and, as has been pointed out, it is difficult to judge whether and how these two processes are interconnected.
Accordingly,
in this study, we aimed to answer the question about autophagy
modulation in breast cancer cells induced to senescence following
doxorubicin treatment. We chose MDA-MB-231 and MCF-7 cells. MDA-MB-231
cells are triple negative breast cancer and have a mutated form of p53, whereas MCF-7 cells possess an estrogen receptor and WT p53. Moreover MDA-MB-231 cells, in contrast to MCF-7, have a very low basal autophagy level.
Despite this, we expected the senescence process in both types of cells
to be connected with polyploidization and senescence escape. Thus, we were interested in propensity to undergo senescence and autophagy activity in the escapers.
Under avsnittet Results hittar vi forskarnas användande av det för studien nödvändiga instrumentet HoloMonitor.
I slutordet tackar man till och med PHI`s representant i Polen för bistånd i att få fram den film som bevisar deras teser, som den utbildning Beata Cieslak hjälpte forskarna med för att kunna använda instrumentet.
Filmen hittas för övrigt i denna
länk under Supplementary Material.
"Video S1: Time lapse of asymmetric division of polyploid giant
MDA-MB-231 cell on day D1+7, documented with holographic microscope."
"We would like to thank Beata Cieslak, from LabSoft, Warsaw, Poland for
help in the acquisition of movies on the HoloMonitor4 and conducting
training for the equipment that was used in this study."
 |
| Figure 4.
Depolyploidization of a giant senescent MDA-MB-231 cell. Cells were
treated with 100 nM doxorubicin for 24 h, then cultured in a fresh
medium and analyzed on subsequent days. (a) Intermediate state of
asymmetric division. Cells were stained for F-actin (green), nuclei
were stained with Hoechst (blue). Scale bar: 50 μm. (b)
Multinucleated polyploidy cell with incomplete mitosis, daughter
subnuclei remain linked by a series of chromosome bridges (arrow),
smaller interphase nuclei marked with a star (*). Toluidine blue
staining at pH 4 after shortened acid hydrolysis. Scale bar: 50 μm. (c) Time lapse of asymmetric division of polyploid giant cancer cell on day D1+7, documented with holographic microscope. |
We extended our studies by using live cell imaging, employing two
different methods—holographic microscopy (HoloMonitor4, LabSoft, Warsaw,
Poland) and scanning disc confocal microscopy (Zeiss, Oberkochen,
Germany). Independently of the technique used, we observed the
asymmetric divisions of some giant polyploid cells, after which both
maternal and descendant cells survived and thrived over the duration of
the movies (3–5 days) (c, Figure S2b, Videos S1 and S2). For comparison, we performed live cell imaging of control MDA-MB-231 cells, which showed proper, symmetric divisions (Figure S2a).
Although these images did not undergo an ameboid-like transition and
cell budding, they showed atypical cell divisions of polyploid/giant
cells. It seems that different atypical cells divisions, not mutually
exclusive, can occur in this cell population, as has been suggested
before [37].
4.15. Live Imaging
To
pinpoint the origin of escaper cells, live imaging techniques for the
division of giant polyploidy MDA-MB-231 cells were employed. Two
independent techniques were used: a holographic microscope, HoloMonitor4
(LabSoft, Warsaw, Poland) and a spinning disc confocal microscope Zeiss
Axio Observer Z.1 Inverted Microscope (Zeiss, Oberkochen, Germany) with
Yokogawa CSU-X1 Spinning Disc (Yokogawa, Tokyo, Japan), with objective:
C APO 40x/1.20 Water. Film acquisition took 3–5 days, time between each
frame: 15–30 min.
Min kommentar
Denna studie är nånting extra.De kunskaper studiens upphovsmän nu gett världens cancerforskare kommer gagna alla som drabbats av bröstcancer.Därför anser jag den ytterst betydelsefull.
Och att PHI`s HoloMonitor varit delaktig i att få fram resultat och ny kunskap känns naturligtvis outstanding.
Sen ger jag mig själv en klapp på axeln,såtillvida att denna studie var riktigt svår att hitta.
Inte ens PHI har den på sin hemsida,det fast studien publicerades för 8 månader sen.
Mvh grävare the99
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