Antitumor activity of Pleurotus ostreatus I-Fraction in a Triple-Negative Breast Cancer murine model

Abstract

Pleurotus ostreatus is an edible mushroom recognized by the Argentine FoodCode. The antitumor activity of its polysaccharides, free or bound to proteins, hasbeen demonstrated in different types of cancer. However, its potential in TripleNegative Breast Cancer (TNBC) is unknown yet. In this context, we have shownthat I-Fraction: a polysaccharide-enriched extract obtained from P. ostreatusexerts antitumor activity on 4T1 and MDA-MB-231 TNBC cell lines in cultive.Therefore, the objectives of this work are to determine the antitumor activity invivo of I-Fraction in TNBC and to deepen its physical-chemical characterization.To this end, we employed a 4T1 syngeneic murine model in which BALB/c micebearing TNBC tumors were treated with I-Fraction extract (25 mg/kg or 50 mg/kg)or vehicle (PBS 1x), 5 times a week for 3 weeks (total doses = 15; subcutaneouslyin the periphery of the tumor). We found that treatment with 50 mg/kg of I-Fractionretarded tumor growth in vivo. From the eleventh dose, I-Fraction-treated micehad significantly smaller tumors than vehicle-treated mice (p < 0.05). In additionto this, the ex vivo tumor volume and weight developed under treatment with 50mg/kg of I-Fraction were significantly lower compared to vehicle treatment (p <0.01). Furthermore, we found a lower number of lung metastases per animal in50 mg/kg I-Fraction-treated mice than in the vehicle-treated mice (p = 0.001).Also, the treatment with I-Fraction did not affect the weight of the mice or theirinternal organs, nor did it alter hematological and biochemical parameters. Onthe other hand, by thermogravimetric analysis, we determined that I-Fractioncontains a moisture of 6.6%, a residue of 12.8% at 700 ºC and a degradationstart temperature of 139.3 ºC. Furthermore, differential scanning calorimetrythermograms showed an exothermic event at 280.7 ºC (∆H=225.6 J/g). Inconclusion, these results demonstrate the antitumor activity in vivo of P. ostreatusI-Fraction in TNBC.