Latar Belakang: Breast Cancer Stem Cells (BCSC) merupakan populasi selkanker payudara yang mempunyai sifat sel punca. BCSC menjaga stabilitas tumordengan menginisiasi pembentukan populasi sel kanker baru serta memberikankekebalan terhadap terapi. BCSC dapat berinteraksi dengan lingkungan mikrotumor yang melepaskan berbagai sitokin dan growth factor, termasuk TGF-β1.Melalui mekanisme autoinduksi, TGF-β1 dapat meningkatkan produksi TGF-β1endogen dan pensinyalan autokrinnya. Pensinyalan autokrin TGF-β1 dapatmeningkatkan pengaruh tumor promotor TGF-β1 dalam perkembangan kankermelalui penguatan karakter kepuncaan dan sifat tumorigenik. Penelitian inibertujuan untuk enganalisis efek pemberian TGF-β1 rekombinan manusia pada selpunca kanker payudara (aldehyde dehydrogenase positive, ALDH+) terhadapekspresi marker kepuncaan melalui pensinyalan autokrin TGF-β1. Sebagaipembanding digunakan kanker payudara subtipe triple negative (TNBC).Metode: BCSCs manusia (ALDH+) dan TNBC (MDA-MB-231) dikultur dalamDulbecco's Modified Eagle Medium/Nutrient Mixture F12/HG (DMEM F12/HG)dengan suplemen 0,1 ng/ml protein rekombinan TGF-β1 manusia (rhTGF-β1)selama periode 1, 2 dan 4 jam. Medium kultur kemudian diganti dengan DMEMF12/HG tanpa serum selama 24 jam. Tingkat ekspresi mRNA reseptor TGF-β tipe1 (TβR1), TGF-β1, faktor transkripsi pengikat oktamer 4 (OCT4), dan anggota A1keluarga aldehida dehidrogenase 1 (ALDH1A1) dianalisis menggunakan real timereverse transcriptase polymerase chain reactions (RT-qPCR). Kadar protein TGF-β1 dalam media kultur ditentukan dengan menggunakan enzyme-linkedimmunosorbent assay (ELISA). Sifat tumorigenik sel diuji dengan ujimammosphere forming unit (MFU assay).Hasil: Tingkat ekspresi mRNA dan protein TGF-β1 BCSC setelah perlakuantampak meningkat namun tidak pada TNBC. mRNA TβR1 BCSCs meningkat padaperiode perlakuan 1 dan 2 jam, sedangkan pada TNBC hanya pada periode 1 jam.Penanda kepuncaan ALDH1A1 dan OCT4 tampak meningkat pada BCSC namuntidak pada TNBC. Uji MFU menunjukkan sifat tumorigenik kedua kelompok selterutama pada periode perlakuan 2 jam tampak meningkat.Kesimpulan: Perlakuan TGF-β1 dalam konsentrasi rendah dan dalam waktusingkat memicu autoinduksi pada BCSCs yang menyebabkan peningkatan ekspresigen kepuncaan melalui pensinyalan autokrin. Sedangkan pada TNBC, peningkatanekspresi marker kepuncaan tidak terjadi. Namun demikian, sifat tumorigenik BCSCdan TNBC tetap meningkat.

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Background: Breast Cancer Stem Cells (BCSC) is a population of breast cancer

cells that have stem cell characteristics. BCSCs maintain tumor stability by

initiating the formation of new cancer cell populations and providing resistance to

therapy. BCSCs can interact with the tumor microenvironment which releasing

various cytokines and growth factors, including TGF-β1. Through the

autoinduction mechanism, TGF-β1 can increase endogenous TGF-β1 production

and autocrine signaling. TGF-β1 autocrine signaling can increase the tumor

promoter role of TGF-β1 in cancer development by enhancing the stemness and

tumorigenic properties. This study aims to analyze the effect of Human TGF-β1

recombinant protein treatment to breast cancer stem cells (aldehyde dehydrogenase

positive, ALDH+) on the expression of stemness marker through TGF-β1 autocrine

signaling. Triple negative breast cancer (TNBC) was used as a comparison.

Methods: Human BCSCs (ALDH+) and TNBC (MDA-MB-231) were cultured in

Dulbecco's Modified Eagle Medium/Nutrient Mixture F12/HG (DMEM F12/HG)

with 0.1 ng / ml recombinant protein of human TGF-β1 supplementation (rhTGF-

β1) over 1, 2 and 4 hour periods. The culture medium was then replaced with

DMEM F12/HG serum-free for 24 hours. The expression levels of the TGF-β

receptor type 1 (TβR1), TGF-β1, octamer-binding transcription factor 4 (OCT4),

and members of the A1 family of aldehyde dehydrogenase 1 (ALDH1A1) mRNA

were analyzed using real time reverse transcriptase polymerase chain reactions

(RT-qPCR). TGF-β1 protein levels in conditioned medium were determined using

an enzyme-linked immunosorbent assay (ELISA). The tumorigenic properties of

cells were tested by the mammosphere forming unit (MFU) assay.

Results: The expression level of mRNA and TGF-β1 BCSC protein after treatment

appeared to be increased but not in TNBC. mRNA TβR1 BCSCs increased in the

treatment period of 1 and 2 hours, whereas in TNBC only in the 1 hour period. The

markers of ALDH1A1 and OCT4 expression appeared to be increased in BCSC but

not in TNBC. The MFU test showed that the tumorigenic properties of both cell

groups, especially in the 2 hour treatment period, appeared to be increasing.

Conclusion: Treatment of TGF-β1 in low concentrations and in a short time

triggered autoinduction of BCSCs and leads to the increased expression of stemness

genes marker via autocrine signaling. Whereas in TNBC, this increase in the

expression of the stemness markers did not occur. However, the tumorigenic nature

of BCSC and TNBC continues to increase.